From AAS NOVA: “A Solar System–Sized Experiment – New Proposal for Precision Cosmology and More”

From AAS NOVA

5.26.23
Ben Cassese

NASA Pioneer 11

Using a network of faraway telescopes in the outskirts of the solar system, astronomers could measure the distance to much farther away galaxies with exquisite precision. A recent study describes how this tactic works and explores what else we could learn with such a bold experiment.

Very Very Long Baselines

Distance is notoriously a tricky quantity to measure in astrophysical contexts, and astronomers have struggled to size up the universe since Hubble first drew his famous diagram.

Edwin Hubble 1929. PNAS 2003

While they have certainly made progress over the last century, it’s natural to wonder if modern technology could enable an entirely new, more precise way to measure the gaps between galaxies.

A sketch of three detectors and a fast radio burst source. Since the wavefront is slightly curved, the same emission will strike each detector at different times. Using measurements of those differences, astronomers can back out the distance to the source. [Boone and McQuinn 2023]
Figure 1. Example of a detector configuration that can be used to measure the distance to a source from the curvature of its wave front. The signal will arrive at detector B before it is seen at detectors A or C. By comparing the arrival times at the three detectors we can infer the distance to the source. Note that we can only measure the difference in arrival times, not the distances di directly. With two detectors the distance to the source is degenerate with the angular position on the sky θ. With three detectors in two dimensions, or four detectors in three dimensions, this degeneracy is broken and the distance to the source can be inferred.

This thinking led Kyle Boone and Matthew McQuinn (University of Washington) to propose a bold new experiment. Their idea, described in a recent publication in The Astrophysical Journal Letters [below], is to scatter a fleet of radio telescopes throughout the solar system and instruct them to all observe the same flashing, repeating fast radio burst at the same time. Since each flash is emitted equally in all directions at the same time, the wavefront will be slightly curved when it arrives and will strike each satellite at a very slightly different time. Add up these nanosecond delays between each, and with some geometry you can back out the distance to the source.

Such a mission would require solving numerous intense, but feasibly surmountable, engineering challenges. Chief among these, astronomers would have to know the distances between the telescopes to within just a few centimeters, a demanding requirement considering the millions of miles separating them and the many subtle forces that affect their motion. Also, each satellite would need to nurture an ultra-precise atomic clock in the face of the unforgiving vacuum of space. But, should engineers resolve these hindrances, a constellation of four or more telescopes drifting in the outer solar system could pin down the distance to each observed flash to within 1% uncertainty.

Spanning Distances and Disciplines

The uncertainty in a measurement of the distance to a source as a function of the true distance to the source for a number of different satellite configurations. Each color represents a different possible baseline separation, and the thickness of each region marks how the uncertainty changes if the resolution of their separation varies between 0.5 and 2 cm. Note that for a source closer than 100 megaparsecs (approximately 300 million light-years), a 25 AU baseline could measure its distance to better than 1%. [Boone and McQuinn 2023]

This experiment was conceived explicitly with precision cosmology in mind, and as Boone and McQuinn show, would be demonstrably revolutionary in that field. However, should astronomers be audacious enough to build a solar system–sized hammer, there are more than a few outstanding nails the same hardware could bludgeon. Take dark matter, for example: several models suggest that invisible clumps of the stuff should occasionally fly through the solar system at high speed. This experiment would necessarily be sensitive enough to notice the slight gravitational tug of such an encounter, meaning even a non-detection of occasional jostles could help constrain our theories of dark matter’s form. Similarly, the much debated “Planet 9” would be unable to evade such an exquisitely sensitive instrument: over time, even from hundreds of AU away, any large planets lurking in the outer solar system would eventually nudge these radio telescopes out of place.

While this study may never grow into more than a thought experiment, such an exercise is constructive nonetheless and gives the astronomical community a chance to reflect on its current capabilities and muse about its future. That said, a more hopeful interpretation is to take this as a starting point for a grand, exacting, colossal mission that could one day uncover secrets of the universe, and our own backyard, all at once.

Figure 2. The triangular configuration of two detectors and the source used for timing. https://www.researchgate.net

Citation

“Solar System-scale Interferometry on Fast Radio Bursts Could Measure Cosmic Distances with Subpercent Precision,” Kyle Boone and Matthew McQuinn 2023 ApJL 947 L23.

https://iopscience.iop.org/article/10.3847/2041-8213/acc947/pdf

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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Please help promote STEM in your local schools.

Stem Education Coalition

The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

Adopted June 7, 2009

The society was founded in 1899 through the efforts of George Ellery Hale. The constitution of the group was written by Hale, George Comstock, Edward Morley, Simon Newcomb and Edward Charles Pickering. These men, plus four others, were the first Executive Council of the society; Newcomb was the first president. The initial membership was 114. The AAS name of the society was not finally decided until 1915, previously it was the “Astronomical and Astrophysical Society of America”. One proposed name that preceded this interim name was “American Astrophysical Society”.

The AAS today has over 7,000 members and six divisions – the Division for Planetary Sciences (1968); the Division on Dynamical Astronomy (1969); the High Energy Astrophysics Division (1969); the Solar Physics Division (1969); the Historical Astronomy Division (1980); and the Laboratory Astrophysics Division (2012). The membership includes physicists, mathematicians, geologists, engineers and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy.

In 2019 three AAS members were selected into the tenth anniversary class of TED Fellows.

The AAS established the AAS Fellows program in 2019 to “confer recognition upon AAS members for achievement and extraordinary service to the field of astronomy and the American Astronomical Society.” The inaugural class was designated by the AAS Board of Trustees and includes an initial group of 232 Legacy Fellows.

From “Astronomy Magazine” : “Building telescopes on the Moon could transform Astronomy”

From “Astronomy Magazine”

4.26.23
Ian Crawford

The current race to the Moon is opening up opportunities for lunar astronomy.

The farside of the Moon is an attractive place to carry out astronomy. Credit: NASA/Ernie Wright.

Lunar exploration is undergoing a renaissance. Dozens of missions, organized by multiple space agencies — and increasingly by commercial companies — are set to visit the Moon by the end of this decade. Most of these will involve small robotic spacecraft, but NASA’s ambitious Artemis program, aims to return humans to the lunar surface by the middle of the decade.

There are various reasons for all this activity, including geopolitical posturing and the search for lunar resources, such as water-ice at the lunar poles, which can be extracted and turned into hydrogen and oxygen propellant for rockets. However, science is also sure to be a major beneficiary.

The Moon still has much to tell us about the origin and evolution of the solar system. It also has scientific value as a platform for observational astronomy.

The potential role for astronomy of Earth’s natural satellite was discussed at a Royal Society meeting earlier this year. The meeting itself had, in part, been sparked by the enhanced access to the lunar surface now in prospect.

Farside benefits

Several types of astronomy would benefit. The most obvious is radio astronomy, which can be conducted from the side of the Moon that always faces away from Earth — the farside.

The lunar farside is permanently shielded from the radio signals generated by humans on Earth. During the lunar night, it is also protected from the Sun. These characteristics make it probably the most “radio-quiet” location in the whole solar system as no other planet or Moon has a side that permanently faces away from the Earth. It is therefore ideally suited for radio astronomy.

Radio waves are a form of electromagnetic energy — as are, for example, infrared, ultraviolet and visible-light waves. They are defined by having different wavelengths in the electromagnetic spectrum.

Radio waves with wavelengths longer than about 15 meters are blocked by Earth’s ionoshere. But radio waves at these wavelengths reach the Moon’s surface unimpeded. For astronomy, this is the last unexplored region of the electromagnetic spectrum, and it is best studied from the lunar farside.

Observations of the cosmos at these wavelengths come under the umbrella of “low frequency radio astronomy.” These wavelengths are uniquely able to probe the structure of the early universe, especially the cosmic “dark ages” — an era before the first galaxies formed.

Dark Ages and Re-ionization of the Universe Credit: The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL).

At that time, most of the matter in the universe, excluding the mysterious dark matter, was in the form of neutral hydrogen atoms. These emit and absorb radiation with a characteristic wavelength of 21 centimeters. Radio astronomers have been using this property to study hydrogen clouds in our own galaxy — the Milky Way — since the 1950s.

Because the universe is constantly expanding, the 21-cm signal generated by hydrogen in the early universe has been shifted to much longer wavelengths. As a result, hydrogen from the cosmic “dark ages” will appear to us with wavelengths greater than 10 meters. The lunar farside may be the only place where we can study this.

The astronomer Jack Burns provided a good summary of the relevant science background at the recent Royal Society meeting, calling the farside of the Moon a “pristine, quiet platform to conduct low radio frequency observations of the early Universe’s Dark Ages, as well as space weather and magnetospheres associated with habitable exoplanets.”

Signals from other stars

As Burns says, another potential application of farside radio astronomy is trying to detect radio waves from charged particles trapped by magnetic fields — magnetospheres — of planets orbiting other stars.

Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase.

This would help to assess how capable these exoplanets are of hosting life. Radio waves from exoplanet magnetospheres would probably have wavelengths greater than 100 meters, so they would require a radio-quiet environment in space. Again, the farside of the Moon will be the best location.

A similar argument can be made for attempts to detect signals from intelligent aliens. And, by opening up an unexplored part of the radio spectrum, there is also the possibility of making serendipitous discoveries of new phenomena.

Artist’s conception of the LuSEE-Night radio astronomy experiment on the Moon. Credit: NASA/Tricia Talbert.

We should get an indication of the potential of these observations when NASA’s LuSEE-Night mission lands on the lunar farside in 2025 or 2026.

The DOE’s Brookhaven National Laboratory Lunar Surface Electromagnetic Experiment (LuSEE) – Night depiction

Crater depths

The Moon also offers opportunities for other types of astronomy as well. Astronomers have lots of experience with optical and infrared telescopes operating in free space, such as the Hubble telescope and JWST. However, the stability of the lunar surface may confer advantages for these types of instruments.

Moreover, there are craters at the lunar poles that receive no sunlight. Telescopes that observe the universe at infrared wavelengths are very sensitive to heat and therefore have to operate at low temperatures. JWST, for example, needs a huge sunshield to protect it from the Sun’s rays. On the Moon, a natural crater rim could provide this shielding for free.

The Moon’s low gravity may also enable the construction of much larger telescopes than is feasible for free-flying satellites. These considerations have led the astronomer Jean-Pierre Maillard to suggest that the Moon may be the future of infrared astronomy.

The cold, stable environment of permanently shadowed craters may also have advantages for the next generation of instruments to detect gravitational waves — “ripples” in space-time caused by processes such as exploding stars and colliding black holes.

Moreover, for billions of years, the Moon has been bombarded by charged particles from the Sun — solar wind — and galactic cosmic rays. The lunar surface may contain a rich record of these processes. Studying them could yield insights into the evolution of both the Sun and the Milky Way.

For all these reasons, astronomy stands to benefit from the current renaissance in lunar exploration. In particular, astronomy is likely to benefit from the infrastructure built up on the Moon as lunar exploration proceeds. This will include both transportation infrastructure — rockets, landers, and other vehicles — to access the surface, as well as humans and robots on-site to construct and maintain astronomical instruments.

But there is also a tension here: Human activities on the lunar farside may create unwanted radio interference, and plans to extract water-ice from shadowed craters might make it difficult for those same craters to be used for astronomy. As my colleagues and I recently argued, we will need to ensure that lunar locations that are uniquely valuable for astronomy are protected in this new age of lunar exploration.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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Please help promote STEM in your local schools.

Stem Education Coalition

Astronomy is a magazine about the science and hobby of Astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

Astronomy was founded in 1973 by Stephen A. Walther, a graduate of The University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at The University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However, he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

From The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH): “Silence reveals insights in search for extraterrestrial life”

From The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH)

4.28.23
Jan Overney

The search for radio signals from extraterrestrial civilizations has yet to yield evidence of alien technological activity. Research carried out at EPFL suggests we continue searching while optimizing the use of available resources.

For over sixty years, amateur and professional astronomers have been monitoring the sky in the search for extraterrestrial intelligence (SETI). So far, to no avail. But how should we read the absence of alien radio signals? Is it time we stop looking? Or should we double down and look harder, peering ever deeper into our galaxy? A recent statistical analysis of the sixty-year silence suggests a simple, optimistic explanation and urges the SETI community to continue searching, but to stay patient, as the chances for detecting signals in the coming sixty years are slim.

The prevailing explanations for the absence of electromagnetic signals from extraterrestrial societies fall into two extreme categories, says Claudio Grimaldi from EPFL’s Laboratory of Statistical Biophysics. The “optimistic” camp holds that we’ve been using detectors that are not sensitive enough or missed incoming signals because we’ve been pointing our radio telescopes in the wrong direction. The “pessimistic” camp, on the other hand, interprets the silence as indicating the absence of alien life in our galaxy.

According to Grimaldi’s study, published in The Astronomical Journal [below], there’s a third explanation. “We’ve only been looking for 60 years. Earth could simply be in a bubble that just happens to be devoid of radio waves emitted by extraterrestrial life,” he says.

Modeling the Milky Way as a sponge

Grimaldi’s study builds on a statistical model initially developed to model porous materials such as sponges, which he sees as a fitting analogy for the question at hand: “You can imagine the sponge’s solid matter to represent electromagnetic signals radiating spherically from a planet harboring extraterrestrial life into space.” In this analogy, the sponge’s holes – its pores – would represent regions where signals are absent.

By repurposing mathematical tools to study porous materials and using Bayesian statistics, Grimaldi was able to draw quantitative conclusions from the sixty years of observed silence. His findings are conditional on the assumptions that there is at least one electromagnetic signal of technological origin in the galaxy at any given time and that Earth has been in a silent bubble, or a “pore,” for at least 60 years.

“If it is true that we’ve been in a void region for sixty years, our model suggests that there are less than one to five electromagnetic emissions per century anywhere in our galaxy. This would make them about as rare as supernovas in the Milky Way,” says Grimaldi. In the most optimistic scenario, we would have to wait over 60 years for one of these signals to reach our planet. In the least optimistic scenario, that number would go up to around 2000 years. Whether we detect the signals when they cross our path is another question. In either case, our radio telescopes would have to be pointed in the right direction to see them.

Defining best practices to continue searching

The search for extraterrestrial intelligence currently has the wind in its sails, buoyed by the discovery, around 20 years ago, of the first planets beyond our solar system. Today, researchers assume there could be as many as 10 billion Earth-like planets – rocky, the right size, and located at the right distance from the sun to harbor life. Their sheer number increases the likelihood that technological life may have developed on one of them.

This has led to new initiatives across the SETI community. The privately funded “Breakthrough Listen” project, the largest of its kind, has put close to 100 million dollars towards dedicating radio telescope time to search for techno-signals from extraterrestrial civilizations.

___________________________________________________________________
Breakthrough Listen Project

UC Observatories Lick Automated Planet Finder fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California

Green Bank Radio Telescope, West Virginia, now the center piece of the Green Bank Observatory, being cut loose by the National Science Foundation, supported by Breakthrough Listen Project, West Virginia University, and operated by the nonprofit Associated Universities, Inc.

CSIRO-Commonwealth Scientific and Industrial Research Organisation (AU) Parkes Observatory [ Murriyang, the traditional Indigenous name] , located 20 kilometres north of the town of Parkes, New South Wales, Australia, 414.80m above sea level.

SKA SARAO Meerkat telescope(SA) 90 km outside the small Northern Cape town of Carnarvon, SA.

Newly added

University of Arizona Veritas Four Čerenkov telescopes A novel gamma ray telescope under construction at the CfA Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, altitude 2,606 m 8,550 ft. A large project known as the Čerenkov Telescope Array, composed of hundreds of similar telescopes to be situated at Roque de los Muchachos Observatory [Instituto de Astrofísica de Canarias ](ES) in the Canary Islands and Chile at European Southern Observatory Cerro Paranal(EU) site. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev. ___________________________________________________________________
With the initiative ending in two years, Grimaldi says that it’s a good time to think about how to pursue the search for extraterrestrial intelligence in the future.

Laser SETI, the future of SETI Institute research.

Alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument, developed at the U Toronto Dunlap Institute for Astronomy and Astrophysics (CA) and brought to UCSD and installed at the UC Santa Cruz Lick Observatory Nickel Telescope. (Photo by Laurie Hatch)

LaserSETI observatory installation at Haleakala Observatory in Maui, Hawai’i, aimed East.

SETI Institute

“The dream of the SETI community is to look for signals all the time, across the entire sky. Even today’s largest telescopes can only see a small fraction of the sky. Today, there are telescope arrays, such as the Allen Telescope Array (ATA) in California, that point in different directions and can be directed at specific regions to get more detailed information when necessary.

SETI Institute Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, Altitude 986 m (3,235 ft), the origins of the Institute’s search.

The same is true for optical telescopes.”

“But,” says Grimaldi, “the truth is, we don’t know where to search, at which frequencies and wavelengths. We are currently looking at other phenomena using our telescopes, so the best strategy might be to adopt the SETI community’s past approach of using data from other astrophysical studies – detecting radio emissions from other stars or galaxies – to see if they contain any techno-signals, and make that the standard practice.”

Ineffective or just unlucky?

Asked whether he considers his conclusions encouraging or discouraging, Grimaldi laughed and said: “This is something we need to think about. We may have been unlucky in that we discovered how to use radio telescopes just as we were crossing a portion of space in which electromagnetic signals from other civilizations were absent. To me, this hypothesis seems less extreme than assuming that we are constantly bombarded by signals from all sides but are, for some reason, unable to detect them.”

The Astronomical Journal
See the science paper for instructive material with images.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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Please help promote STEM in your local schools.

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EPFL campus

The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH) is a research institute and university in Lausanne, Switzerland, that specializes in natural sciences and engineering. It is one of the two Swiss Federal Institutes of Technology, and it has three main missions: education, research and technology transfer.

The QS World University Rankings ranks EPFL(CH) 14th in the world across all fields in their 2020/2021 ranking, whereas Times Higher Education World University Rankings ranks EPFL(CH) as the world’s 19th best school for Engineering and Technology in 2020.

EPFL(CH) is located in the French-speaking part of Switzerland; the sister institution in the German-speaking part of Switzerland is The Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich] (CH). Associated with several specialized research institutes, the two universities form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles Polytechniques Fédérales] (CH) which is directly dependent on the Federal Department of Economic Affairs, Education and Research. In connection with research and teaching activities, EPFL(CH) operates a nuclear reactor CROCUS; a Tokamak Fusion reactor; a Blue Gene/Q Supercomputer; and P3 bio-hazard facilities.

ETH Zürich, EPFL (Swiss Federal Institute of Technology in Lausanne) [École Polytechnique Fédérale de Lausanne](CH), and four associated research institutes form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles polytechniques fédérales] (CH) with the aim of collaborating on scientific projects.

The roots of modern-day EPFL(CH) can be traced back to the foundation of a private school under the name École Spéciale de Lausanne in 1853 at the initiative of Lois Rivier, a graduate of the École Centrale Paris (FR) and John Gay the then professor and rector of the Académie de Lausanne. At its inception it had only 11 students and the offices were located at Rue du Valentin in Lausanne. In 1869, it became the technical department of the public Académie de Lausanne. When the Académie was reorganized and acquired the status of a university in 1890, the technical faculty changed its name to École d’Ingénieurs de l’Université de Lausanne. In 1946, it was renamed the École polytechnique de l’Université de Lausanne (EPUL). In 1969, the EPUL was separated from the rest of the University of Lausanne and became a federal institute under its current name. EPFL(CH), like ETH Zürich (CH), is thus directly controlled by the Swiss federal government. In contrast, all other universities in Switzerland are controlled by their respective cantonal governments. Following the nomination of Patrick Aebischer as president in 2000, EPFL(CH) has started to develop into the field of life sciences. It absorbed the Swiss Institute for Experimental Cancer Research (ISREC) in 2008.

In 1946, there were 360 students. In 1969, EPFL(CH) had 1,400 students and 55 professors. In the past two decades the university has grown rapidly and as of 2012 roughly 14,000 people study or work on campus, about 9,300 of these being Bachelor, Master or PhD students. The environment at modern day EPFL(CH) is highly international with the school attracting students and researchers from all over the world. More than 125 countries are represented on the campus and the university has two official languages, French and English.

Organization

EPFL is organized into eight schools, themselves formed of institutes that group research units (laboratories or chairs) around common themes:

School of Basic Sciences
Institute of Mathematics
Institute of Chemical Sciences and Engineering
Institute of Physics
European Centre of Atomic and Molecular Computations
Bernoulli Center
Biomedical Imaging Research Center
Interdisciplinary Center for Electron Microscopy
MPG-EPFL Centre for Molecular Nanosciences and Technology
Swiss Plasma Center
Laboratory of Astrophysics

School of Engineering

Institute of Electrical Engineering
Institute of Mechanical Engineering
Institute of Materials
Institute of Microengineering
Institute of Bioengineering

School of Architecture, Civil and Environmental Engineering

Institute of Architecture
Civil Engineering Institute
Institute of Urban and Regional Sciences
Environmental Engineering Institute

School of Computer and Communication Sciences

Algorithms & Theoretical Computer Science
Artificial Intelligence & Machine Learning
Computational Biology
Computer Architecture & Integrated Systems
Data Management & Information Retrieval
Graphics & Vision
Human-Computer Interaction
Information & Communication Theory
Networking
Programming Languages & Formal Methods
Security & Cryptography
Signal & Image Processing
Systems

School of Life Sciences

Bachelor-Master Teaching Section in Life Sciences and Technologies
Brain Mind Institute
Institute of Bioengineering
Swiss Institute for Experimental Cancer Research
Global Health Institute
Ten Technology Platforms & Core Facilities (PTECH)
Center for Phenogenomics
NCCR Synaptic Bases of Mental Diseases

College of Management of Technology

Swiss Finance Institute at EPFL
Section of Management of Technology and Entrepreneurship
Institute of Technology and Public Policy
Institute of Management of Technology and Entrepreneurship
Section of Financial Engineering

College of Humanities

Human and social sciences teaching program

EPFL Middle East

Section of Energy Management and Sustainability

In addition to the eight schools there are seven closely related institutions

Swiss Cancer Centre
Center for Biomedical Imaging (CIBM)
Centre for Advanced Modelling Science (CADMOS)
École Cantonale d’art de Lausanne (ECAL)
Campus Biotech
Wyss Center for Bio- and Neuro-engineering
Swiss National Supercomputing Centre

From The National Radio Astronomy Observatory: “Far Far Away – Just How Distant Is That Galaxy?”

From The National Radio Astronomy Observatory

4.4.23
Brian Koberlein

Galaxies in Stephen’s Quintet. Credit: NASA, ESA, and the Hubble SM4 ERO Team.

In December 2022, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA)[below] confirmed the discovery of one of the most distant galaxies ever observed. The faint radio light ALMA captured began its journey to us when the universe was less than 360 million years old. It’s a tremendously distant galaxy, but just how far away is it really? The answer is a bit complicated, and it depends on what you mean by distance.

To begin with, astronomers can’t directly measure the distance of galaxies billions of light years away. Instead, they measure what is known as redshift, or z. In this case, the team measured a particular wavelength of light emitted by oxygen known as OIII. When we observe the OIII emission line in a lab here on Earth, it has a wavelength of 88 micrometers. The OIII line ALMA observed in this particular galaxy was much longer, about 1,160 micrometers. Since red light has a longer wavelength than blue light, we say the observed OII line is shifted to the red, or redshifted. Given these two numbers, calculating z is easy. It is just the relative redshift of the observed light, So z = (1160 – 88)/88 = 12.2 The bigger the z, the greater the redshift, and z = 12.2 is the largest confirmed redshift of a galaxy so far.

Image of the galaxy as seen by JWST and its radio spectrum as seen by ALMA. Credit: NASA/ESA/CSA/T. Treu, UCLA/NAOJ/T. Bakx, Nagoya U.

So what does this have to do with distance? There are two ways light from a galaxy can be redshifted. The first is known as the Doppler shift and is caused by the physical motion of a galaxy through space. You’re probably familiar with this effect in sound. When a train speeds past you, its horn sounds higher as the train approaches you and lower as it passes you and rolls away. The sound waves are bunched up as the train moves toward you and have a higher pitch, and they are stretched out as the train moves away from you, thus a lower pitch. The same thing happens with light. If a galaxy is moving toward us its light is blueshifted, and the light is redshifted if it’s moving away from us.

The second way redshift can occur is through cosmic expansion. The universe is expanding, and this means as light travels to us from a distant galaxy its wavelength is stretched out by the expansion of space. The longer the light travels the more the light is stretched, so the more the light is redshifted. This is known as cosmological redshift. For distant galaxies, almost all the redshift we observe is cosmological. This is how we know high redshift galaxies such as this one are very, very far away.

But this still doesn’t tell us the specific distance. To determine that we have to look at how the universe expands over time. Right now there’s a bit of uncertainty about the rate of cosmic expansion, known as the Hubble parameter. The Planck mission observations of the cosmic microwave background put the value at about 68 (km/s)/Mpc, while observations of the Hubble and Gaia spacecraft give it a higher value of about 72 (km/s)/Mpc. The bigger the value, the faster the universe is expanding and the farther away distant galaxies are. If we pick a middle value of 70 (km/s)/Mpc, then we can calculate a reasonable distance using general relativity, but even then our answer will depend on how we define distance.

One definition would be to ask how long the light traveled from the galaxy to us. This is known as the light travel time and turns out to be about 13.1 billion years. Since the universe is about 13.46 billion years old (based on the Hubble parameter we chose), that means the light left the galaxy when the universe was about 360 million years old. This definition is useful for astronomers since distant galaxies tell us about the early universe. It’s more important for astronomers to know a galaxy’s place in history than its distance.

Since the light traveled for 13.1 billion years, does that mean the galaxy is 13.1 billion light-years away? Not quite. Because of cosmic expansion, the light traveled for much longer than it would have if the universe wasn’t expanding. The galaxy was closer to us when the light began its journey. Much closer. If we calculate how far away the galaxy was from us 13.1 billion years ago, we get 2.4 billion light-years. So this galaxy was only 2.4 billion light years away, but the universe expanded so much that its light took 13.1 billion light-years to reach us.

As light travels through the expanding universe, its wavelength is stretched. Credit: Leah Hustak (STScI)/NASA/ESA.

Of course, you probably want to know how far away the galaxy is now. Sure, the galaxy was 2.4 billion light years away, but once the light started heading our way the galaxy continued to move away from us because of the ever-expanding universe. So where is the galaxy now? If you do the math, it turns out the galaxy is now about 32 billion light-years away. But wait a minute? How can we see a galaxy 32 billion light-years away if the universe is less than 14 billion years old? The answer is that we can’t. ALMA’s view of the galaxy is how it looked when it was only 2.4 billion light-years away. We will never be able to see what the galaxy looks like now. It is too far away, and the universe is expanding too quickly for that light to reach us. We only see the optical echo of where it was and how it used to appear.

All of this is strange enough to tie anyone’s brain into a knot. This is why astronomers focus on the redshift z, and why we usually talk about how old the universe was when the galactic light began its journey. That’s enough to tell us that the galaxy is far away and seen from long ago. So long ago and so far away that its distance is hard to define.

See the full article here .

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The National Radio Astronomy Observatory is a facility of The National Science Foundation, operated under cooperative agreement by The Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

ngVLA, to be located near the location of the NRAO Karl G. Jansky Very Large Array site on the plains of San Agustin, fifty miles west of Socorro, NM, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

National Radio Astronomy Observatory Very Long Baseline Array.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL))/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

From “Science Magazine” : “Giant array of low-cost telescopes could speed hunt for radio bursts and massive black holes”

From “Science Magazine”

3.31.23
Daniel Clery

Closely packed radio dishes enable wide-field real-time sky surveys.

Caltech Deep Synoptic Array 110 at Owens Valley Radio Observatory.

The Deep Synoptic Array 110 is demonstrating how closely packed radio dishes can speed up sky surveys.DSA/CalTech.

When the immense Arecibo radio telescope in Puerto Rico collapsed in 2020, it left gaping holes in astronomy.

NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and Ana G. Méndez University [Universidad Ana G. Méndez, Recinto de Cupey] (PR) Altitude 497 m (1,631 ft), which has now collapsed.

Now, a team from the California Institute of Technology (Caltech) hopes to address some of the gaps with a very different instrument: a tightly packed array of relatively inexpensive radio dishes that aims to quickly image radio sources across wide swaths of the sky. A nearly completed prototype array in California that the team calls a “radio camera” is already locating dozens of the distant, enigmatic eruptions called fast radio bursts (FRBs). Next year, the team hopes to begin construction on a much larger array with 2000 dishes that, together, will match the size of Arecibo.

Maura McLaughlin of West Virginia University is a leader of NANOGrav (the North American Nanohertz Observatory for Gravitational Waves), an effort to search for gravitational waves from supermassive black holes that relied on Arecibo for half its data.

She says they took “a big sensitivity hit” when it was lost. “We really need a new telescope with a similar collecting area,” she says, and Caltech’s planned Deep Synoptic Array (DSA) fits that bill. “It will be a game changer.”

To gain sensitivity, radio astronomers can build big dishes like Arecibo or arrays of smaller dishes. But in most such arrays, the dishes are widely spaced, which sharpens their resolution but creates “a data deluge problem,” says Caltech’s Gregg Hallinan, DSA principal investigator (PI). Producing an image from a scattered array is like looking through a fragmented mirror, he says, and recreating the information from the missing parts is a complex nonlinear process known as deconvolution that can take weeks—or even years.

Many astronomers just want to regularly survey the sky for new objects or monitor sources for subtle changes without a heavy processing burden. Caltech’s solution, Hallinan says, is to “fill the mirror up” by packing low-cost dishes together. That makes deconvolution easier and should enable DSA to construct images in real time.

The team has nearly finished assembling its prototype, the DSA-110, a T-shaped array of 95 dishes spaced 1 meter apart at Caltech’s Owens Valley Radio Observatory in California plus another 15 “outriggers” spread out more than 1 kilometer away.

Caltech Deep Synoptic Array being built at Owens Valley Radio Observatory Owens Valley, California, Altitude 1,222 m (4,009 ft)

California Institute of Technology Owens Valley Radio Observatory, Owens Valley, California, Altitude 1,222 m (4,009 ft). Credit: Caltech.

To keep construction costs to $4 million, the instrument uses commercially available 4.6-meter dishes, homemade amplifiers, and wave-channeling feeds fashioned out of cake tins. Most radio telescopes require expensive cryogenic cooling to reduce amplifier noise, but Caltech’s engineers have squeezed similar performance out of room-temperature circuits. (Co-PI Vikram Ravi admits they perform less well in the summer heat.)

With a wide field of view, DSA-110 is good at detecting FRBs, intense blasts of radio waves lasting only milliseconds, coming from all over the sky. Several thousand have been detected, but little more than a dozen have been traced to their home galaxies, which might hold clues to what is powering the bursts. DSA-110 aims to localize many more. If a burst is detected, data from the outrigger dishes allow the telescope to zoom in and pin the FRB to its galaxy.

During 2022, with more than half the dishes in place including the outriggers, DSA-110 identified source galaxies for about 20 FRBs, overtaking the number of localized sources found by all other telescopes. When completed this summer, it should localize a couple of FRBs every week, Ravi says. “It’s going to be a lot of fun.”

The results so far are already confounding theorists. They predicted FRBs are most likely to come from galaxies that are rapidly forging new stars. Such galaxies abound in massive stars that quickly run out of fusion fuel and collapse into tiny stellar remnants rippling with energy called magnetars—the favored engines for blasting out FRBs. But DSA-110 has found FRBs in quiescent galaxies whose magnetars would have long fizzled out. That suggests FRBs might have other sources besides magnetars, says Victoria Kaspi of McGill University. Just this week in Nature Astronomy [below], researchers reported an FRB that appeared to come from the merger of two neutron stars. “Having many FRBs localized is important,” Kaspi says. “We may be able to see different populations [of FRBs] from different sources.”

Meanwhile, the Caltech team is gearing up for the next phase: DSA-2000. At 19 by 15 kilometers, it will be too big for Owens Valley so the team is looking at Hot Creek Valley in Nevada, a sparsely populated, radio quiet region. To keep costs low, the Caltech team plans to make its own 5-meter dishes by molding sheets of aluminum. Although DSA-2000 won’t be as sensitive as other planned radio observatories, such as the Square Kilometre Array in South Africa and Australia, it will beat them on survey speed. Existing surveys have logged 10 million radio sources across the sky, Hallinan says. DSA-2000 will boost that number 100-fold to 1 billion, giving astronomers, for example, a better picture of how galaxies form and grow, and allowing them to capture fleeting sources like merging neutron stars over a much wider volume.

Later this year, the team will apply to the U.S. National Science Foundation to supplement the private sources that have funded development work. If the team can raise the $144 million needed to build the array, DSA-2000 could start logging tens of thousands of FRBs in 2026. That could enable astronomers to start using FRBs as a mapping tool. As the compact pulses move through space, they get smeared by the gas they pass through—giving astronomers a clue to the location of gas around and between galaxies that is normally invisible to telescopes. Astronomers don’t know where half the normal matter in the universe is; FRBs could help them find it.

One-quarter of its time will be devoted to eavesdropping on another hidden component of the universe: the colossal black holes lurking at the centers of galaxies with masses of millions or billions of suns. When galaxies merge, the newly formed galaxy ought to end up with two of these lumbering giants, circling each other warily and churning out long, languorous gravitational waves. Detectors on Earth have detected the shorter, sharper waves generated by collisions of star-size black holes. But it takes a detector light-years across to pick up these long waves. NANOGrav’s strategy is to studiously observe pulsars, spinning stellar fossils that emit metronomic radio pulses hundreds of times a second. A passing gravitational wave would slightly shift a pulsar’s repetition rate as it ripples space between the pulsar and Earth.

More than a decade of watching several dozen pulsars has yet to turn up a firm detection. But with DSA-2000 monitoring more pulsars, more accurately and more often, a signal might emerge, says NANOGrav member Chiara Mingarelli of the University of Connecticut, Storrs. That would open “a new frontier,” she says, revealing giant black holes performing a hidden pas de deux. “DSA-2000 will be transformational for gravitational wave astronomy.”

Nature Astronomy

See the full article here .

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From The MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE) : “Weighing OJ 287 and the project MOMO”

From The MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE)

2.23.23 [Just today in social media.]

Dr. Stefanie Komossa
+49 228 525-386
skomossa@mpifr.de

Dr. Alex Kraus
Station Manager, Effelsberg Radio Observatory
+49 2257 301-101
akraus@mpifr.de

Dr. Norbert Junkes
Press and Public Outreach
+49 228 525-399
njunkes@mpifr.de

The densest and longest radio-to-high-energy view of the binary black hole at the center of the active galaxy OJ 287.

An international research group led by Stefanie Komossa from the MPG Institute for Radio Astronomy in Bonn, Germany, presents important new results on the galaxy OJ 287, based on the most dense and longest radio-to-high-energy observations to date. The scientists were able to test crucial binary model predictions using multiple observing tools including the Effelsberg radio telescope [below] and the Neil Gehrels Swift Observatory.

National Aeronautics and Space Administration Penn State Neil Gehrels Swift X-ray, and UV/Visible light Observatory.

For the first time, an independent black hole mass determination of the system was performed and the amount of matter in a disk surrounding the black hole could be estimated.

The results show that an exceptionally massive black hole exceeding 10 billion solar masses is no longer needed. Instead, the results favor models with a smaller mass of 100 million solar masses for the primary black hole. Several outstanding mysteries, including the apparent absence of the latest big outburst of OJ 287 (which has now been identified) and the much-discussed emission mechanism during the main outbursts, can be solved this way. Independent results on blazar physics that trace processes near the jet launching region were obtained.

These findings have strong implications for the theoretical modeling of supermassive black hole binary systems and their evolution, for understanding the physics of accretion and jet launching near supermassive black holes, for future pulsar timing vs space-based gravitational wave detection from this system, and a direct spatial resolution of this system with the Event Horizon Telescope or the future SKA

The findings are presented in two papers published in MNRAS Letters [below] and The Astrophysical Journal [below].

Fig. 1: The left panel shows a deep ultraviolet image of OJ 287 and its environment taken with Swift. This is one of the deepest UV images of that part of the sky ever taken, combining 560 single exposures. The brightest source in the field is OJ 287. The black hole region itself cannot be resolved in the UV image. The right panel depicts an artist’s view of the very center of OJ 287, including the accretion disk, the jet, and a second black hole orbiting the primary black hole which has a mass of 100 million solar masses. © S. Komossa et al.; NASA/JPL-Caltech.

Blazars are galaxies that host powerful, long-lived jets of relativistic particles that are launched in the immediate vicinity of their central supermassive black hole.

When two galaxies collide and merge, supermassive binary black holes are formed. These binaries are of great interest because they play a key role in the evolution of galaxies and the growth of supermassive black holes. Furthermore, coalescing binaries are the universe’s loudest sources of gravitational waves. The future ESA cornerstone mission LISA (Laser Interferometer Space Antenna) aims to directly detect such waves in the gravitational wave spectrum. The search for supermassive binary black hole systems is currently in full swing.

OJ 287 is a bright blazar in the direction of the constellation Cancer at a distance of about 5 billion light years. It is one of the best candidates for hosting a compact binary supermassive black hole. Exceptional outbursts of radiation which repeat every 11 to 12 years are OJ 287’s claim to fame. Some of these are so bright, that OJ 287 temporarily becomes the brightest source of its type in the sky. Its repeating outbursts are so remarkable, that several different binary models have been proposed and discussed in the literature to explain them.

As the second black hole in the system orbits the other more massive black hole it imposes semi-periodic signals on the light output of the system by affecting either the jet or the accretion disk of the more massive black hole.

However, until now there has been no direct independent determination of the black hole mass, and none of the models could be critically tested in systematic observing campaigns, because these campaigns lacked a broad-band coverage involving radiation of many different frequencies. For the first time, multiple simultaneous X-ray, UV and radio observations, along with optical and gamma-ray bands were now used. The new findings were made possible by the MOMO project (“Multiwavelength Observations and Modelling of OJ 287”), which is one of the densest and longest-lasting multi-frequency monitoring projects of any blazar involving X-rays, and the densest ever of OJ 287.

“OJ 287 is an excellent laboratory for studying the physical processes that reign in one of the most extreme astrophysical environments: disks and jets of matter in the immediate vicinity of one or two supermassive black holes”, says Stefanie Komossa from the MPG Institute for Radio Astronomy (MPIfR), the first author of the two studies presented here. “Therefore, we initiated the project MOMO. It consists of high-cadence observations of OJ 287 at more than 14 frequencies from the radio to the high energy regime lasting for years, plus dedicated follow-ups at multiple ground- and space-based facilities when the blazar is found at exceptional states.”

“Thousands of data sets have already been taken and analyzed. This makes OJ 287 stand out as one of the best-monitored blazars ever in the UV-X-ray-radio regime”, adds co-author Alex Kraus from the MPIfR. “The Effelsberg radio telescope and the space mission Swift play a central role in the project.”

The Effelsberg telescope provides information at a broad range of radio frequencies, whereas the Neil Gehrels Swift observatory is used to obtain simultaneous UV, optical and X-ray data. High-energy gamma-ray data from the Fermi Gamma-Ray Space Observatory, as well as radio data from the Submillimeter Array (SMA) at Maunakea/Hawai’i, have been added.

National Aeronautics and Space Administration Fermi Gamma-Ray Large Area Telescope.

National Aeronautics and Space Administration Fermi Gamma Ray Space Telescope

CFA Harvard Smithsonian Submillimeter Array on Mauna Kea, Hawai’i, Altitude 4205 m (13796 ft).

The jet dominates the electromagnetic emission of OJ 287 due to its blazar nature. The jet is so bright, that it outshines the radiation from the accretion disk (the radiation of matter falling into the black hole), making it hard to impossible to observe the emission from the accretion disk, as if we were looking directly into a car headlight. However, due to the large number of MOMO observations that densely covered the light output of OJ 287 (a new observation almost every other day with Swift), “deep fades” were discovered. These are times when the jet emission fades away rapidly, allowing the researchers to constrain the emission from the accretion disk. The results show that the disk of matter surrounding the black hole is at least a factor of 10 fainter than previously thought, with a luminosity estimated to be no more than 2 x 10^46 erg/s, corresponding to about 5 trillion times the luminosity of our sun (5 x 10^12 Lʘ).

For the first time the mass of the primary black hole of OJ 287 was derived from the motion of gaseous matter bound to the black hole. The mass amounts to 100 million times the mass of our sun. “This result is very important, as the mass is a key parameter in the models that study the evolution of this binary system: How far are the black holes separated, how quickly will they merge, how strong is their gravitational wave signal?” comments Dirk Grupe of the Northern Kentucky University (USA), a co-author in both studies.

“The new results imply that an exceptionally large mass of the black hole of OJ 287, exceeding 10 billion solar masses, is no longer required; neither is a particularly luminous disk of matter accreting onto the black hole required”, adds Thomas Krichbaum from the MPIfR, a co-author of the ApJ paper. The results rather favor a binary model of more modest mass.

The study also resolves two old puzzles: the apparent absence of the latest of the bright outbursts which OJ 287 is famous for, and the emission mechanism behind the outbursts. The MOMO observations allow for the precise timing of the latest outburst. It did not occur in October 2022, as predicted by the “huge-mass” model, but rather in 2016-2017, which MOMO extensively covered. Furthermore, radio observations with the Effelsberg 100-m telescope reveal that these outbursts are non-thermal in nature, implying that jet processes are the power source of the outbursts.

The MOMO results affect ongoing and future search strategies for additional binary systems using major large observatories such as the Event Horizon Telescope and, in the future, the SKA Observatory. They could enable direct radio detection and spatial resolution of the binary sources in OJ 287 and similar systems, as well as the detection of gravitational waves from these systems in the future. OJ 287 will no longer serve as a target for pulsar-timing arrays due to the derived black hole mass of 100 million solar masses, but will be within the range of future space-based observatories (upon coalescence).

“Our results have strong implications for theoretical modeling of binary supermassive black hole systems and their evolution, for understanding the physics of accretion and ejection of matter in the vicinity of supermassive black holes, and for the electromagnetic identification of binary systems in general”, concludes Stefanie Komossa.

The research team comprises S. Komossa, D. Grupe, A. Kraus, M.A. Gurwell, Z. Haiman, F.K. Liu, A. Tchekhovskoy, L.C. Gallo, M. Berton, R. Blandford, J.L. Gómez, and A.G. Gonzalez (MNRAS Letter), and S. Komossa, A. Kraus, D. Grupe, A.G. Gonzalez, M.A. Gurwell, L.C. Gallo, F.K. Liu, I. Myserlis, T.P. Krichbaum, S. Laine, U. Bach, J.L. Gómez, M.L. Parker, S. Yao, and M. Berton (ApJ Paper). Stefanie Komossa, Alex Kraus, Thomas Krichbaum, Uwe Bach and Su Yao are affiliated with the MPIfR.

MNRAS Letters
The Astrophysical Journal
See the above science paper for instructive material with images.

See the full article here .

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MPIFR campus

Effelsberg Radio Telescope- a radio telescope in the Ahr Hills (part of the Eifel) in Bad Münstereifel(DE)

The MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie] (DE) is located in Bonn, Germany. It is one of 80 institutes in the MPG Society.

By combining the already existing radio astronomy faculty of the University of Bonn led by Otto Hachenberg with the new MPG institute the MPG Institute for Radio Astronomy was formed. In 1972 the 100-m radio telescope in Effelsberg was opened. The institute building was enlarged in 1983 and 2002.

The institute was founded in 1966 by the MPG Society as the “MPG Institut für Radioastronomie (MPIfR) (DE)”.

The foundation of the institute was closely linked to plans in the German astronomical community to construct a competitive large radio telescope in (then) West Germany. In 1964, Professors Friedrich Becker, Wolfgang Priester and Otto Hachenberg of the Astronomische Institute der Universität Bonn submitted a proposal to the Stiftung Volkswagenwerk for the construction of a large fully steerable radio telescope.

In the same year the Stiftung Volkswagenwerk approved the funding of the telescope project but with the condition that an organization should be found, which would guarantee the operations. It was clear that the operation of such a large instrument was well beyond the possibilities of a single university institute.

Already in 1965 the MPG Society decided in principle to found the MPG Institut für Radioastronomie. Eventually, after a series of discussions, the institute was officially founded in 1966.

MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the Max Planck Society in 1948 in honor of its former president, theoretical physicist Max Planck. The society is funded by the federal and state governments of Germany as well as other sources.

According to its primary goal, the MPG Society supports fundamental research in the natural, life and social sciences, the arts and humanities in its 83 (as of January 2014) MPG Institutes. The society has a total staff of approximately 17,000 permanent employees, including 5,470 scientists, plus around 4,600 non-tenured scientists and guests. Society budget for 2015 was about €1.7 billion.

The MPG Institutes focus on excellence in research. The MPG Society has a world-leading reputation as a science and technology research organization, with 33 Nobel Prizes awarded to their scientists, and is generally regarded as the foremost basic research organization in Europe and the world. In 2013, the Nature Publishing Index placed the MPG institutes fifth worldwide in terms of research published in Nature journals (after Harvard University, The Massachusetts Institute of Technology, Stanford University and The National Institutes of Health). In terms of total research volume (unweighted by citations or impact), the Max Planck Society is only outranked by The Chinese Academy of Sciences [中国科学院](CN), The Russian Academy of Sciences [Росси́йская акаде́мия нау́к](RU) and Harvard University. The Thomson Reuters-Science Watch website placed the MPG Society as the second leading research organization worldwide following Harvard University, in terms of the impact of the produced research over science fields.

The MPG Society and its predecessor Kaiser Wilhelm Society hosted several renowned scientists in their fields, including Otto Hahn, Werner Heisenberg, and Albert Einstein.

History

The organization was established in 1911 as the Kaiser Wilhelm Society, or Kaiser-Wilhelm-Gesellschaft (KWG), a non-governmental research organization named for the then German emperor. The KWG was one of the world’s leading research organizations; its board of directors included scientists like Walther Bothe, Peter Debye, Albert Einstein, and Fritz Haber. In 1946, Otto Hahn assumed the position of President of KWG, and in 1948, the society was renamed the Max Planck Society (MPG) after its former President (1930–37) Max Planck, who died in 1947.

The MPG Society has a world-leading reputation as a science and technology research organization. In 2006, the Times Higher Education Supplement rankings of non-university research institutions (based on international peer review by academics) placed the MPG Society as No.1 in the world for science research, and No.3 in technology research (behind AT&T Corporation and The DOE’s Argonne National Laboratory.

The domain mpg.de attracted at least 1.7 million visitors annually by 2008 according to a Compete.com study.

MPG Institutes and research groups

The MPG Society consists of over 80 research institutes. In addition, the society funds a number of Max Planck Research Groups (MPRG) and International Max Planck Research Schools (IMPRS). The purpose of establishing independent research groups at various universities is to strengthen the required networking between universities and institutes of the Max Planck Society.
The research units are primarily located across Europe with a few in South Korea and the U.S. In 2007, the Society established its first non-European centre, with an institute on the Jupiter campus of Florida Atlantic University (US) focusing on neuroscience.
The MPG Institutes operate independently from, though in close cooperation with, the universities, and focus on innovative research which does not fit into the university structure due to their interdisciplinary or transdisciplinary nature or which require resources that cannot be met by the state universities.

Internally, MPG Institutes are organized into research departments headed by directors such that each MPI has several directors, a position roughly comparable to anything from full professor to department head at a university. Other core members include Junior and Senior Research Fellows.

In addition, there are several associated institutes:
International Max Planck Research Schools
Together with the Association of Universities and other Education Institutions in Germany, the Max Planck Society established numerous International Max Planck Research Schools (IMPRS) to promote junior scientists:

• Cologne Graduate School of Ageing Research, Cologne
• International Max Planck Research School for Intelligent Systems, at the Max Planck Institute for Intelligent Systems located in Tübingen and Stuttgart
• International Max Planck Research School on Adapting Behavior in a Fundamentally Uncertain World (Uncertainty School), at the Max Planck Institutes for Economics, for Human Development, and/or Research on Collective Goods
• International Max Planck Research School for Analysis, Design and Optimization in Chemical and Biochemical Process Engineering, Magdeburg
• International Max Planck Research School for Astronomy and Cosmic Physics, Heidelberg at the MPI for Astronomy
• International Max Planck Research School for Astrophysics, Garching at the MPI for Astrophysics
• International Max Planck Research School for Complex Surfaces in Material Sciences, Berlin
• International Max Planck Research School for Computer Science, Saarbrücken
• International Max Planck Research School for Earth System Modeling, Hamburg
• International Max Planck Research School for Elementary Particle Physics, Munich, at the MPI for Physics
• International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Marburg at the Max Planck Institute for Terrestrial Microbiology
• International Max Planck Research School for Evolutionary Biology, Plön at the Max Planck Institute for Evolutionary Biology
• International Max Planck Research School “From Molecules to Organisms”, Tübingen at the Max Planck Institute for Developmental Biology
• International Max Planck Research School for Global Biogeochemical Cycles, Jena at the Max Planck Institute for Biogeochemistry
• International Max Planck Research School on Gravitational Wave Astronomy, Hannover and Potsdam MPI for Gravitational Physics
• International Max Planck Research School for Heart and Lung Research, Bad Nauheim at the Max Planck Institute for Heart and Lung Research
• International Max Planck Research School for Infectious Diseases and Immunity, Berlin at the Max Planck Institute for Infection Biology
• International Max Planck Research School for Language Sciences, Nijmegen
• International Max Planck Research School for Neurosciences, Göttingen
• International Max Planck Research School for Cognitive and Systems Neuroscience, Tübingen
• International Max Planck Research School for Marine Microbiology (MarMic), joint program of the Max Planck Institute for Marine Microbiology in Bremen, the University of Bremen, the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, and the Jacobs University Bremen
• International Max Planck Research School for Maritime Affairs, Hamburg
• International Max Planck Research School for Molecular and Cellular Biology, Freiburg
• International Max Planck Research School for Molecular and Cellular Life Sciences, Munich
• International Max Planck Research School for Molecular Biology, Göttingen
• International Max Planck Research School for Molecular Cell Biology and Bioengineering, Dresden
• International Max Planck Research School Molecular Biomedicine, program combined with the ‘Graduate Programm Cell Dynamics And Disease’ at the University of Münster and the Max Planck Institute for Molecular Biomedicine
• International Max Planck Research School on Multiscale Bio-Systems, Potsdam
• International Max Planck Research School for Organismal Biology, at the University of Konstanz and the Max Planck Institute for Ornithology
• International Max Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS RECHARGE), Mülheim an der Ruhr, at the Max Planck Institute for Chemical Energy Conversion
• International Max Planck Research School for Science and Technology of Nano-Systems, Halle at Max Planck Institute of Microstructure Physics
• International Max Planck Research School for Solar System Science at the University of Göttingen hosted by MPI for Solar System Research
• International Max Planck Research School for Astronomy and Astrophysics, Bonn, at the MPI for Radio Astronomy (formerly the International Max Planck Research School for Radio and Infrared Astronomy)
• International Max Planck Research School for the Social and Political Constitution of the Economy, Cologne
• International Max Planck Research School for Surface and Interface Engineering in Advanced Materials, Düsseldorf at Max Planck Institute for Iron Research GmbH
• International Max Planck Research School for Ultrafast Imaging and Structural Dynamics, Hamburg

Max Planck Schools

• Max Planck School of Cognition
• Max Planck School Matter to Life
• Max Planck School of Photonics

Max Planck Center

• The Max Planck Centre for Attosecond Science (MPC-AS), POSTECH Pohang
• The Max Planck POSTECH Center for Complex Phase Materials, POSTECH Pohang

Max Planck Institutes

Among others:
• Max Planck Institute for Neurobiology of Behavior – caesar, Bonn
• Max Planck Institute for Aeronomics in Katlenburg-Lindau was renamed to Max Planck Institute for Solar System Research in 2004;
• Max Planck Institute for Biology in Tübingen was closed in 2005;
• Max Planck Institute for Cell Biology in Ladenburg b. Heidelberg was closed in 2003;
• Max Planck Institute for Economics in Jena was renamed to the Max Planck Institute for the Science of Human History in 2014;
• Max Planck Institute for Ionospheric Research in Katlenburg-Lindau was renamed to Max Planck Institute for Aeronomics in 1958;
• Max Planck Institute for Metals Research, Stuttgart
• Max Planck Institute of Oceanic Biology in Wilhelmshaven was renamed to Max Planck Institute of Cell Biology in 1968 and moved to Ladenburg 1977;
• Max Planck Institute for Psychological Research in Munich merged into the Max Planck Institute for Human Cognitive and Brain Sciences in 2004;
• Max Planck Institute for Protein and Leather Research in Regensburg moved to Munich 1957 and was united with the Max Planck Institute for Biochemistry in 1977;
• Max Planck Institute for Virus Research in Tübingen was renamed as Max Planck Institute for Developmental Biology in 1985;
• Max Planck Institute for the Study of the Scientific-Technical World in Starnberg (from 1970 until 1981 (closed)) directed by Carl Friedrich von Weizsäcker and Jürgen Habermas.
• Max Planck Institute for Behavioral Physiology
• Max Planck Institute of Experimental Endocrinology
• Max Planck Institute for Foreign and International Social Law
• Max Planck Institute for Physics and Astrophysics
• Max Planck Research Unit for Enzymology of Protein Folding
• Max Planck Institute for Biology of Ageing

From The National Astronomical Observatory of Japan [国立天文台] (JP): “Small But Mighty – New Superconducting Amplifiers Deliver High Performance at Lower Power Consumption”

From The National Astronomical Observatory of Japan [国立天文台] (JP)

3.20.23

An “SIS amplifier” using two SIS mixers, one at each ends. (Credit: NAOJ)

Researchers have devised a new concept of superconducting microwave low-noise amplifiers for use in radio wave detectors for radio astronomy observations, and successfully demonstrated a high-performance cooled amplifier with power consumption three orders of magnitude lower than that of conventional cooled semiconductor amplifiers. This result is expected to contribute to the realization of large-scale multi-element radio cameras and error-tolerant quantum computers, both of which require a large number of low-noise microwave amplifiers.

The devise they used is called an SIS mixer. The SIS mixer is named after its structure, a very thin film of insulator material sandwiched between two layers of superconductors (S-I-S). In a radio telescope, cosmic radio waves collected by an antenna are fed into an SIS mixer, and the output signal is amplified by low-noise semiconductor amplifiers. An SIS mixer operates in a very low temperature environment, as low as 4 Kelvin (-269 degrees Celsius), and the amplifiers are also operated at that temperature.

To improve the performance of radio telescopes, researchers are developing a large-format radio camera equipped with 2D arrays of SIS mixers and amplifiers. However, the power consumption is a limiting factor. The typical power consumption of a semiconductor amplifier is about 10 mW, and by assembling 100 sets of detectors, the total power consumption reaches the maximum cooling capability of a 4 Kelvin refrigerator.

The research team led by Takafumi Kojima, an associate professor at the National Astronomical Observatory of Japan (NAOJ), has come up with a simple but innovative idea to realize a superconductor amplifier by connecting two SIS mixers. The team exploits the basic functions of the SIS mixer: frequency conversion and signal amplification. “The most important point is that the power consumption of an SIS mixer is, in principle, as low as microwatts,” says Kojima. “This is three orders of magnitude less than that of a cooled semiconductor amplifier.”

After obtaining successful preliminary results in 2018, the team advanced both the theoretical studies of the system and the physical implementation of its various components. In the end, the research team optimized the system and realized an “SIS amplifier” with 5 – 8 dB (three to six times) gain below the frequency of 5 GHz and a typical noise temperature of 10 K, which is comparable to the current cooled semiconductor amplifiers such as HEMT and HBT, but with much lower power consumption.

“By changing the configuration of the components, we can further improve the gain and low-noise performance of an SIS amplifier,” explains Kojima. “The idea of connecting two SIS mixers has broader applications for making various electronics that have functions other than amplification.”

Interestingly, this low-noise, low-power-consumption amplifier is also highly anticipated for large-scale error-tolerant quantum computers. Currently available quantum computers are small-scale with less than 100 qubits, but larger-scale, error-tolerant general-purpose quantum computers will require more than 1 million qubits. To handle a large number of qubits, a large number of amplifiers must also be installed, and dramatic reductions in amplifier power consumption are needed.

NAOJ has experience in the development of superconducting receivers for a number of radio telescopes, including NAOJ’s Nobeyama 45-meter Radio Telescope [below], which started operation in 1982. NAOJ is also currently working to upgrade the superconducting receivers to improve the performance of the Atacama Large Millimeter/submillimeter Array (ALMA) [below], which is operated in the Republic of Chile in cooperation with East Asia, Europe, and North America. Of the 10 types of receivers (corresponding to 10 different frequency bands) currently installed on ALMA, three were developed by NAOJ, and the SIS chips at the heart of these receivers were also developed and produced in the cleanroom of the NAOJ Advanced Technology Center (ATC). The NAOJ ATC continues to promote research on the miniaturization and integration of superconducting circuits, not only for the realization of more powerful radio telescopes, but also for their potential as the basis of various technologies that will support society in the new era, such as quantum computing.

Research results were presented in Applied Physics Letters published on February 14, 2023.

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The National Astronomical Observatory of Japan (NAOJ) [国立天文台] (JP) is an astronomical research organization comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of The University of Tokyo [東京大学](JP), International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University [名古屋大学](JP).

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences .

NAOJ Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level.

European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte] (EU)/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Solar Flare Telescope.

Nobeyama Millimeter Array Radioheliograph, located near Minamimaki, Nagano at an elevation of 1350m.

Mizusawa VERA Observatory.

Okayama Astrophysical Observatory.

NAOJ Kyoto U 3.8m SEMEI Telescope.

From “Astronomy Magazine” : “Radio interference from satellites is threatening astronomy”

From “Astronomy Magazine”

3.9.23
Christopher Gordon De Pree | Deputy Electromagnetic Spectrum Manager, National Radio Astronomy Observatory
Christopher R. Anderson | Associate Professor of Electrical Engineering, United States Naval Academy
Mariya Zheleva | Assistant Professor of Computer Science, University at Albany, State University of New York

Just as human development leads to more light pollution increasing numbers of satellites are leading to more radio interference.

“Visible light is just one part of the electromagnetic spectrum that astronomers use to study the universe. The James Webb Space Telescope was built to see infrared light, other space telescopes capture X-ray images, and observatories like the Green Bank Telescope, the Very Large Array, the Atacama Large Millimeter Array, and dozens of other observatories around the world work at radio wavelengths.

Green Bank Radio Telescope, West Virginia now the center piece of the Green Bank Observatory being cut loose by the National Science Foundation, supported by Breakthrough Listen Project, West Virginia University, and operated by the nonprofit Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Observatory (CL).

Radio telescopes are facing a problem. All satellites, whatever their function, use radio waves to transmit information to the surface of the Earth. Just as light pollution can hide a starry night sky, radio transmissions can swamp out the radio waves astronomers use to learn about black holes, newly forming stars and the evolution of galaxies.

We are three scientists who work in astronomy and wireless technology. With tens of thousands of satellites expected to go into orbit in the coming years and increasing use on the ground, the radio spectrum is getting crowded. Radio quiet zones – regions, usually located in remote areas, where ground-based radio transmissions are limited or prohibited – have protected radio astronomy in the past.

As the problem of radio pollution continues to grow, scientists, engineers and policymakers will need to figure out how everyone can effectively share the limited range of radio frequencies. One solution that we have been working on for the past few years is to create a facility where astronomers and engineers can test new technologies to prevent radio interference from blocking out the night sky.

Different telescopes capture different parts of the electromagnetic spectrum, with radio telescopes collecting radiation of the longest wavelengths. Credit: InductiveLoad/NASA/Wikimedia Commons, CC BY-SA

Astronomy with radio waves

Radio waves are the longest wavelength emissions on the electromagnetic spectrum, meaning that the distance between two peaks of the wave is relatively far apart. Radio telescopes collect radio waves in wavelengths from millimeter to meter wavelengths.

Messier 87*, The first image of the event horizon of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Image via The Event Horizon Telescope Collaboration released on 10 April 2019 via National Science Foundation.

This is the first image of Sagittarius A* – [SGR A*] the supermassive black hole at the center of the Milky Way. Credit: The Event Horizon Telescope Collaboration.

Even if you are unfamiliar with radio telescopes, you have probably heard about some of the research they do. The fantastic first images of accretion disks around black holes were both produced by the Event Horizon Telescope.

The locations of the radio dishes of the Event Horizon Telescope array in 2019. Since then new telescopes have been added.

This telescope is a global network of eight radio telescopes, and each of the individual telescopes that make up the Event Horizon Telescope is located in a place with very little radio frequency interference: a radio quiet zone.

A radio quiet zone is a region where ground-based transmitters like cellphone towers are required to lower their power levels so as not to affect sensitive radio equipment. The U.S. has two such zones. The largest is the National Radio Quiet Zone, which covers 13,000 square miles (34,000 square kilometers) mostly in West Virginia and Virginia.

National Radio Quiet Zone (NRQZ)
The National Radio Quiet Zone (NRQZ) was set aside by the federal government to provide a geographical region to protect sensitive instrumentation from Radio Frequency Interference (RFI).

It contains the Green Bank Observatory. The other, the Table Mountain Field Site and Radio Quiet Zone, in Colorado, supports research by a number of federal agencies.

Table Mountain Field Site and Radio Quiet Zone, Colorado.

Similar radio quiet zones are home to telescopes in Australia, South Africa and China.

Inyarrimanha Ilgari Bundara, our Murchison Radio-astronomy Observatory is one of the best locations in the world to operate telescopes that listen for radio signals from space.

Our observatory in the heart of Wajarri Country in remote Western Australia is home to our ASKAP radio telescope as well as other international radio astronomy projects. We currently host the Curtin University-led Murchison Widefield Array (MWA) and Arizona State University’s Experiment to Detect the Global Epoch of Reionization Signature (EDGES) instrument.
Credit: CSIRO.

Karoo radio quite zone, South Africa

FAST-Five-hundred-meter Aperture Spherical radio Telescope [[五百米口径球面射电望远镜] (CN), located in the Dawodang depression in Pingtang County, Guizhou Province, South China.

Large satellite constellations, like those of Starlink, can be seen marching in lines across night skies and harm both visible and radio astronomy. STARLINK satellites train seen from earth – SpaceX Elon Musk.

A satellite boom

On Oct. 4, 1957, the Soviet Union launched Sputnik into orbit. As the small satellite circled the globe, amateur radio enthusiasts all over the world were able to pick up the radio signals it was beaming back to Earth. Since that historic flight, wireless signals have become part of almost every aspect of modern life – from aircraft navigation to Wi-Fi – and the number of satellites has grown exponentially.

The more radio transmissions there are the more challenging it becomes to deal with interference in radio quiet zones. Existing laws do not protect these zones from satellite transmitters, which can have devastating effects. In one example, transmissions from an Iridium satellite completely obscured the observations of a faint star made in a protected band allocated to radio astronomy.

Two images from the Very Large Array in New Mexico show what a faint star looks like to a radio telescope without satellite interference, left, and with satellite interference, right. G. Taylor, UNM, CC BY-ND.

Satellite internet networks like Starlink, OneWeb and others will eventually be flying over every location on Earth and transmitting radio waves down to the surface. Soon, no location will be truly quiet for radio astronomy.

Just as with light pollution, the more development there is on Earth and in the sky, the more radio interference there will be. Gppercy/Wikimedia Commons, CC BY-SA

Interference in the sky and on the ground

The problem of radio interference is not new.

In the 1980s, the Russian Global Navigation Satellite System – essentially the Soviet Union’s version of GPS – began transmitting at a frequency that was officially protected for radio astronomy. Researchers recommended a number of fixes for this interference. By the time operators of the Russian navigation system agreed to change the transmitting frequency of the satellites, a lot of harm had already been done due to the lack of testing and communication.

Many satellites look down at Earth using parts of the radio spectrum to monitor characteristics like surface soil moisture that are important for weather prediction and climate research. The frequencies they rely on are protected under international agreements but are also under threat from radio interference.

A recent study showed that a large fraction of NASA’s soil moisture measurements experience interference from ground-based radar systems and consumer electronics. There are systems in place to monitor and account for the interference, but avoiding the problem altogether through international communication and prelaunch testing would be a better option for astronomy.

Most radio telescopes, like the Atacama Large Millimeter Array in Chile, are in areas far from any source of interference. But a new site designed to test technologies and interference solutions could prevent future problems.
Credit: J. Guarda/ALMA (ESO/NAOJ/NRAO) CC BY.

Solutions to a crowded radio spectrum

As the radio spectrum continues to get more crowded, users will have to share. This could involve sharing in time, in space or in frequency. Regardless of the specifics, solutions will need to be tested in a controlled environment. There are early signs of cooperation. The National Science Foundation and SpaceX recently announced an astronomy coordination agreement to benefit radio astronomy.

Working with astronomers, engineers, software and wireless specialists, and with the support of the National Science Foundation, we have been leading a series of workshops to develop what a national radio dynamic zone could provide. This zone would be similar to existing radio quiet zones, covering a large area with restrictions on radio transmissions nearby. Unlike a quiet zone, the facility would be outfitted with sensitive spectrum monitors that would allow astronomers, satellite companies and technology developers to test receivers and transmitters together at large scales. The goal would be to support creative and cooperative uses of the radio spectrum. For example, a zone established near a radio telescope could test schemes to provide broader bandwidth access for both active uses, like cell towers, and passive uses, like radio telescopes.

For a new paper our team just published [IEEEXplore (below)], we spoke with users and regulators of the radio spectrum, ranging from radio astronomers to satellite operators. We found that most agreed that a radio dynamic zone could help solve, and potentially avoid, many critical interference issues in the coming decades.

Such a zone doesn’t exist yet, but our team and many people across the U.S. are working to refine the concept so that radio astronomy, Earth-sensing satellites and government and commercial wireless systems can find ways to share the precious natural resource that is the radio spectrum.”

IEEEXplore

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Astronomy is a magazine about the science and hobby of Astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

Astronomy was founded in 1973 by Stephen A. Walther, a graduate of The University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at The University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However, he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

From “Science Magazine” : “In India train tracks threaten a giant telescope”

From “Science Magazine”

3.7.23
Sanjay Kumar

Upgraded Giant Metrewave Radio Telescope, an array of thirty telescopes, located near Pune in India.

For nearly 30 years, the Giant Metrewave Radio Telescope (GMRT) here 200 kilometers east of Mumbai has listened for faint low-frequency radio signals emanating from the distant reaches of the cosmos. Its Y-shaped network of 30 antennas, each 45 meters wide, spreads over 25 square kilometers. The dishes have helped astronomers from dozens of nations study some of the most distant known galaxies and one of the universe’s biggest known explosions, an outburst from a giant black hole in the Ophiuchus Supercluster. The telescope is among the most sensitive in the world at these low frequencies, but it could soon be deafened by signals emanating from a mundane source: electric trains.

Last month, the Indian government gave approval “in principle” for construction of a pair of high-speed rail lines that would slice through the GMRT’s array, edging within 960 meters of some antennas. By 2026, planners envision 48 electric passenger trains, as well as cargo haulers, plying the tracks each day as they travel some 235 kilometers between the cities of Pune and Nashik.

That prospect has astronomers very worried. “The key villain here is the pantograph, which is perched on top of the rail engine, constantly touching the overhead high-tension power line to draw electricity to propel the train,” says Yashwant Gupta, director of the National Centre for Radio Astrophysics, a division of the Tata Institute of Fundamental Research, which operates the GMRT. As the pantograph makes and breaks contact with the line, he says, it produces sparks and electromagnetic bursts that can “drown the entire spectrum of faint radio signals the telescope is devoted to study.” Railway communications equipment can add to the interference, Gupta notes, making it impossible for the GMRT to detect signals within its listening range of 100 to 1450 megahertz.

To protect the telescope, astronomers are asking planners to consider rerouting the railway or placing the tracks and equipment inside tunnels. “We would like to coexist,” Gupta says, but the lines “should be taken at least 15 to 20 kilometers away from the GMRT to minimize radio interference.”

Rail project officials declined to comment on the astronomers’ concerns. But local politicians have long been outspoken in their support for the project. Amol Kolhe, who represents the region in Parliament, says although the GMRT is a source of scientific pride, the need to protect it from electromagnetic interference has held back the region’s economy. “Scientific projects should not come in the way of development,” he says, predicting that if “the railway project is stalled or significantly compromised, there definitely will be agitations” among his constituents, many of whom support the project.

At the root of the impasse is India’s rapid economic development. When astronomers selected the GMRT site in 1990, it was sparsely populated and surrounding hills protected it from electromagnetic smog produced by distant urban areas. Over time, however, nearby communities have grown, bringing with them many technologies that produce radio signals, including power lines, lights, engines, cellular networks, and even mosquito-killing devices.

Today, the GMRT is one of the few radio telescopes located in a densely populated region, and its staff go to enormous lengths to protect it from disruptive signals. Researchers carefully track possible sources of interference within 30 kilometers of the telescope, and periodically venture into communities to work with businesses, farmers, and others to alter equipment or practices to reduce problematic noise. Because of restrictions, “even mobile phones came late to the area,” Kolhe says.

Still, GMRT officials argue its presence has not harmed the local economy. Gupta notes his center has over the years signed off on the launch of more than 2000 businesses in the area, including two sugar processing mills. And it has worked with mobile phone companies, wind turbine operators, and India’s air force to resolve potential conflicts.

Despite its age and the arrival of newer radio telescopes, astronomers say the GMRT still has a role to play in research. In particular, it can listen for the faint hum produced by the clouds of electrically neutral hydrogen atoms that existed in the early universe. The telescope “is making important contributions by surveying for neutral hydrogen,” which provides clues to the evolution of stars and galaxies, says physicist Jacqueline Hewitt of the Massachusetts Institute of Technology. “The GMRT still has a unique place among the radio telescopes available to the community,” says astronomer Raffaella Morganti of the Kapteyn Astronomical Institute at the University of Groningen.

Gupta and other astronomers are hoping they can find a way for the telescope and the railway line to coexist. Some say they are frustrated that, so far, rail officials have declined to engage in discussions while pushing the government to produce final approvals. Others worry that, with several major elections looming, elected officials will be reluctant to delay or redesign the project.

Kolhe, however, says he is “open to all the ideas for solution.” And Gupta hopes substantive talks will start soon. “This is a very good time for us to get into detailed discussions” about how to allow trains to start rolling on Earth without drowning out the sounds of the cosmos.

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From The National Radio Astronomy Observatory: “Astronomers Find Evidence for Most Powerful Pulsar in Distant Galaxy”

From The National Radio Astronomy Observatory

6.15.22 [Just found this]
Dave Finley
Public Information Officer
(505) 241-9210
dfinley@nrao.edu

Credit: Melissa Weiss, NRAO/AUI/NSF.

Astronomers analyzing data from the VLA Sky Survey (VLASS) have discovered one of the youngest known neutron stars — the superdense remnant of a massive star that exploded as a supernova. Images from the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) [below] indicate that bright radio emission powered by the spinning pulsar’s magnetic field has only recently emerged from behind a dense shell of debris from the supernova explosion.

Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at Mullard Radio Astronomy Observatory, University of Cambridge (UK), taken for the Daily Herald newspaper in 1968. Denied the Nobel.

The object, called VT 1137-0337, is in a dwarf galaxy 395 million light-years from Earth. It first appeared in a VLASS image made in January of 2018. It did not appear in an image of the same region made by the VLA’s FIRST Survey in 1998. It continued to appear in later VLASS observations in 2018, 2019, 2020, and 2022.

“What we’re most likely seeing is a pulsar wind nebula,” said Dillon Dong, a Caltech graduate student who will begin a Jansky Postdoctoral Fellowship at the National Radio Astronomy Observatory (NRAO) later this year. A pulsar wind nebula is created when the powerful magnetic field of a rapidly spinning neutron star accelerates surrounding charged particles to nearly the speed of light.

“Based on its characteristics, this is a very young pulsar — possibly as young as only 14 years, but no older than 60 to 80 years,” said Gregg Hallinan, Dong’s Ph.D advisor at Caltech.

The scientists reported their findings at the American Astronomical Society’s meeting in Pasadena, California.

Dong and Hallinan discovered the object in data from VLASS, an NRAO project that began in 2017 to survey the entire sky visible from the VLA — about 80 percent of the sky. Over a period of seven years, VLASS is conducting a complete scan of the sky three times, with one of the objectives to find transient objects. The astronomers found VT 1137-0337 in the first VLASS scan from 2018.

Comparing that VLASS scan to data from an earlier VLA sky survey called FIRST revealed 20 particularly luminous transient objects that could be associated with known galaxies.

“This one stood out because its galaxy is experiencing a burst of star formation, and also because of the characteristics of its radio emission,” Dong said. The galaxy, called SDSS J113706.18-033737.1, is a dwarf galaxy containing about 100 million times the mass of the Sun.

In studying the characteristics of VT 1137-0337, the astronomers considered several possible explanations, including a supernova, gamma ray burst, or tidal disruption event in which a star is shredded by a supermassive black hole. They concluded that the best explanation is a pulsar wind nebula.

In this scenario, a star much more massive than the Sun exploded as a supernova, leaving behind a neutron star.

Neutron Star L. Calçada/ European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte] (EU) (CL)

Most of the original star’s mass was blown outward as a shell of debris. The neutron star spins rapidly, and as its powerful magnetic field sweeps through the surrounding space it accelerates charged particles, causing strong radio emission.

Initially, the radio emission was blocked from view by the shell of explosion debris. As that shell expanded, it became progressively less dense until eventually the radio waves from the pulsar wind nebula could pass through.

“This happened between the FIRST observation in 1998 and the VLASS observation in 2018,” Hallinan said.

Probably the most famous example of a pulsar wind nebula is the Crab Nebula in the constellation Taurus, the result of a supernova that shone brightly in the year 1054.

The Crab Nebula, Messier 1 by the Hubble Space Telescope – among the largest ever produced image with the Earth-orbiting observatory – gives the most detailed view so far of the. The Crab is arguably the single most interesting object, as well as one of the most studied, in all of astronomy. The image is the largest ever taken with Hubble’s WFPC2 workhorse camera. This composite image of the Crab Nebula was assembled by combining data from five telescopes spanning nearly the entire breadth of the electromagnetic spectrum. Credit: G. Dubner (University of Buenos Aires [Universidad de Buenos Aires] (AR)) National Aeronautics Space Agency, European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganization](EU), National Radio Astronomy Observatory /Associated Universities IncNational Science Foundation.

The Crab is readily visible today in small telescopes.

“The object we have found appears to be approximately 10,000 times more energetic than the Crab, with a stronger magnetic field,” Dong said. “It likely is an emerging ‘super Crab’,” he added.

While Dong and Hallinan consider VT 1137-0337 to most likely be a pulsar wind nebula, it also is possible that its magnetic field may be strong enough for the neutron star to qualify as a magnetar — a class of super-magnetic objects.

Iconic depiction of Magnetar in Westerlund 1 Credit L. Calçada/ The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europaiche Sûdsternwarte] (EU)(CL).

Magnetars are a leading candidate for the origin of the mysterious Fast Radio Bursts (FRBs) now under intense study.

“In that case, this would be the first magnetar caught in the act of appearing, and that, too, is extremely exciting,” Dong said.

Indeed some Fast Radio Bursts have been found to be associated with persistent radio sources, the nature of which also is a mystery. They bear a strong resemblance in their properties to VT 1137-0337, but have shown no evidence of strong variability.

“Our discovery of a very similar source switching on suggests that the radio sources associated with FRBs also may be luminous pulsar wind nebulae,” Dong said.

The astronomers plan to conduct further observations to learn more about the object and to monitor its behavior over time.

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The National Radio Astronomy Observatory is a facility of The National Science Foundation, operated under cooperative agreement by The Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

ngVLA, to be located near the location of the NRAO Karl G. Jansky Very Large Array site on the plains of San Agustin, fifty miles west of Socorro, NM, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

National Radio Astronomy Observatory Very Long Baseline Array.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL))/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.