From National Radio Astronomy Observatory: “VLBA Makes First Direct Distance Measurement to Magnetar”

From National Radio Astronomy Observatory

September 18, 2020
Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu

Credit: Sophia Dagnello, NRAO/AUI/NSF.

Astronomers using the National Science Foundation’s Very Long Baseline Array (VLBA) [below] have made the first direct geometric measurement of the distance to a magnetar within our Milky Way Galaxy — a measurement that could help determine if magnetars are the sources of the long-mysterious Fast Radio Bursts (FRBs).

Magnetars are a variety of neutron stars — the superdense remains of massive stars that exploded as supernovae — with extremely strong magnetic fields. A typical magnetar magnetic field is a trillion times stronger than the Earth’s magnetic field, making magnetars the most magnetic objects in the Universe. They can emit strong bursts of X-rays and gamma rays, and recently have become a leading candidate for the sources of FRBs.

A magnetar called XTE J1810-197, discovered in 2003, was the first of only six such objects found to emit radio pulses. It did so from 2003 to 2008, then ceased for a decade. In December of 2018, it resumed emitting bright radio pulses.

A team of astronomers used the VLBA to regularly observe XTE J1810-197 from January to November of 2019, then again during March and April of 2020. By viewing the magnetar from opposite sides of the Earth’s orbit around the Sun, they were able to detect a slight shift in its apparent position with respect to background objects much more distant. This effect, called parallax, allows astronomers to use geometry to directly calculate the object’s distance.

“This is the first parallax measurement for a magnetar, and shows that it is among the closest magnetars known — at about 8100 light-years — making it a prime target for future study,” said Hao Ding, a graduate student at the Swinburne University of Technology in Australia.

On April 28, a different magnetar, called SGR 1935+2154, emitted a brief radio burst that was the strongest ever recorded from within the Milky Way. While not as strong as FRBs coming from other galaxies, this burst suggested to astronomers that magnetars could generate FRBs.

Fast radio bursts were first discovered in 2007. They are very energetic, and last at most a few milliseconds. Most have come from outside the Milky Way. Their origin remains unknown, but their characteristics have indicated that the extreme environment of a magnetar could generate them.

“Having a precise distance to this magnetar means that we can accurately calculate the strength of the radio pulses coming from it. If it emits something similar to an FRB, we will know how strong that pulse is,” said Adam Deller, also of Swinburne University. “FRBs vary in their strength, so we would like to know if a magnetar pulse comes close or overlaps with the strength of known FRBs,” he added.

“A key to answering this question will be to get more distances to magnetars, so we can expand our sample and obtain more data. The VLBA is the ideal tool for doing this,” said Walter Brisken, of the National Radio Astronomy Observatory.

In addition, “We know that pulsars, such as the one in the famous Crab Nebula, emit ‘giant pulses,’ much stronger than their usual ones. Determining the distances to magnetars will help us understand this phenomenon, and learn if maybe FRBs are the most extreme example of giant pulses,” Ding said.

The ultimate goal is to determine the exact mechanism that produces FRBs, the scientists said.

Ding, Deller, Brisken, and their colleagues reported their results in the Monthly Notices of the Royal Astronomical Society.

See the full article here .

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NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

NRAO ngVLA, located near the location of the VLA site on the plains of San Agustin, fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico

NRAO/VLBA

ESO/NRAO/NAOJ 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.

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 Max Planck Institute for Radio Astronomy: “Astronomy became big here”

From Max Planck Institute for Radio Astronomy

September 16, 2020

Prof. Dr. Michael Kramer
Max Planck Institute for Radio Astronomy, Bonn
+49 228 525-278
mkramer@mpifr-bonn.mpg.de

Dr. Robert Adam
Southafrican Radioastronomy Observatory, Kapstadt
rob@ska.ac.za

The Max Planck Society is investing 20 million Euros in the expansion of the radio telescope MeerKAT in South Africa, which will also be the nucleus of the Square Kilometre Array (SKA).

Both partners, Germany and South Africa, benefit from the MeerKAT collaboration.

SKA Square Kilometer Array

SKA South Africa.

SKA SARAO Meerkat telescope, South African design.

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

SKA will be built in South Africa and Australia and, with a total area of eventually one square kilometre, will capture radio waves in the southern sky. We talked to Robert Adam, Managing Director of the South African Radio Astronomy Observatory (SARAO), and Michael Kramer Director at the Max Planck Institute for Radio Astronomy, about the scientific successes and goals of MeerKAT, the status of SKA and the prospects for science in South Africa and other countries in southern Africa.

Contacts
Prof. Dr. Michael Kramer
Max Planck Institute for Radio Astronomy, Bonn +49 228 525-278 mkramer@mpifr-bonn.mpg.de
Dr. Robert Adam
rob@ska.ac.za Southafrican Radioastronomy Observatory, Kapstadt

September 16, 2020

Interview by Peter Hergersberg

Prof. Kramer, Dr. Adam, which scientific highlights have been achieved with MeerKAT so far?

Kramer: Already the first image of MeerKAT was the most detailed and most impressive image of our Galactic centre so far. MeerKAT has thus already proven that it is the best radio telescope currently available in the world. We have also already discovered several pulsars in globular clusters, which we are now investigating more closely. But we are only at the beginning and are very much looking forward to what we all can do with MeerKAT in the future.

Adam: MeerKAT was only commissioned in mid-2018. In the beginning we first had to get the technology up and running to add the signals from the various antennas coherently – this is an unruly electronic monster. Nevertheless, there were already a number of highlights, for example insight into the jets emerging from the centres of various galaxies. But the large survey projects, for which MeerKAT is particularly well suited, have only just begun.

What insights do you hope to gain from the survey projects?

Adam: Two projects are about pulsars, which emit radio signals at very regular intervals, about their discovery and their timing. In other projects we are creating maps of the neutral hydrogen distribution. Hydrogen is the most common element in the Universe. Its distribution tells us a lot about the structure of the Universe, both on a cosmological and galactic scale. In addition, we study exoplanets orbiting nearby stars, or giant cosmic magnetic fields that still leave us with great mysteries.

What benefit do you expect from the expansion by twenty antennas?

Adam: Not only the sensitivity will increase considerably, but also the resolving power of the telescope will be much better. On the South African side we will equip the antennas with receivers, which will be able to map neutral hydrogen with higher resolution. Our German partners will also install “S-band” detectors on the new antennas, just as they have done with the existing telescopes.

What are these “S-band” receivers for?

Kramer: These receivers allow us to measure at slightly higher frequencies and therefore to look much deeper into our Galaxy – at lower frequencies the interstellar medium obstructs our view somewhat. So we can search for pulsars or observe chemical reactions. We are planning projects that will have a legacy value even when the even larger SKA, the Square Kilometre Array, comes along.

Germany has not officially participated in SKA since 2015, but is still represented by the Max Planck Society? What is the status of this project?

Kramer: The Max-Planck Society is currently acting in the kind of a placeholder role for German community in the SKA project. The society is negotiating right now how German scientists can benefit from the MPG contributions to the SKA.

Adam: The Covid 19 pandemic has slowed the process of setting up the SKA Observatory somewhat, mainly due to travel restrictions. In general, SKA as a multilateral project is more difficult to coordinate than MeerKAT. I have the feeling that the effort for such processes increases quadratically with the number of partners: Not everyone has the money available at the same time, the scientists have promised their governments different things in some cases – you have to take all this into account if you want to get such a project off the ground. You often have to make compromises and cannot simply decide. But we are still on the right track. I think that as soon as the host countries Australia, South Africa and Great Britain as the largest donors have agreed, many things will become easier. China and Italy are also involved, and Germany will hopefully be involved again soon.

Kramer: The good thing is that SKA is a modular system. That’s why you can add antennas step by step. Similar to what we are doing now with MeerKAT. Even if there were not sufficient money at the beginning for the complete expansion, you can already build a telescope that is unique. Then you can add more dishes to telescope when more partners join.

Adam: It is definitely an advantage of radio astronomy that you can build our telescopes step by step. In comparison it’s very difficult to build half an optical telescope.

To what extent do your two organisations benefit from the cooperation?

Kramer: The Southern hemisphere is very interesting for radio astronomy, but there was no radio telescope of this size before MeerKAT. This very sensitive and versatile instrument opens up completely new possibilities for science in terms of sensivitiy and resolution. To be involved in this means what the Max Planck Society stands for: the attempt to push the limits of the possible again and again and thereby gain insight.

Adam: In optical astronomy we have always been quite strong, but in radio astronomy our country is still a newcomer. That is why working with German colleagues on the expansion of MeerKat is highly beneficial for us, because we can build on their scientific experience. This will also help us to build SKA. And we are grateful for the unbureaucratic, cooperative manner of our German colleagues: We solve problems and do not look for ways to fall over them – an experience that we have encountered differently in other cooperations.

Kramer: Apart from the science, we are always impressed by the smart out-of-the-box solutions that South African engineers come up with. For example, South African colleagues have developed hardware to combine all the telescopes’ data. It is now used more or less in this form in many other telescopes around the world, for example in our telescope in Effelsberg, and this even before we decided to join MeerKAT. The exchange of experiences and ideas therefore goes in both directions.

What significance do MeerKAT and later SKA have for science in South Africa and beyond?

Adam: After we left apartheid behind, we had the opportunity to reinvent many things. Before that there was a boycott of scientific institutions, as well as of trade and other things. Now we could suddenly cooperate internationally, especially international investment in our science became possible. So we thought about what could attract scientists from Germany or the USA to South Africa, not as a donor country, but as a country looking for benefits for its own research. That’s how we came to astronomy, because it’s always helpful to look at the Universe from different parts of the world. So we wanted to become hosts for different large telescopes. That’s why we first built the South African Large Telescope, an optical telescope, and then, in Namibia, which belonged to South Africa until 1990, we collaborated in the construction of the the gamma-ray telescope HESS. At SKA we also use international interest and international investment to support South African science and business. We told our cabinet: If you put your money into intelligent people in a great project, you will get more than the project. Silicon Valley would not exist without the Apollo project either. There is a whole range of transfers across disciplines. We can’t tell you what effect it will have, but it will have an effect. And in dealing with Big Data, a key technology not only for astronomy, but for a whole range of areas, we are actually pushing development forward today.

Kramer: There is another good example of a very recent technology transfer: SARAO engineers were hired to build ventilators for the therapy of Covid-19. This shows that people are acquiring skills in our research that are useful for society.

Adam: Of course we chose the Karoo area for MeerKAT because only a few people live there as dense populations are not compatible with astronomy. In radio astronomy, for example, there is interference from mobile phones. But of course there are also people in the Karoo region who, until the start of the MeerKAT project, lived exclusively on agriculture and government aid. We have contributed to diversifying the local economy, for example through hospitality or by selling vehicles and diesel. In addition, it is of course much more sensible to train young people from the area as craftsmen and technicians. An example from the lower tech services: all the workers who splice fibre are from the area. You can start at that level and then hopefully get further qualifications. After all, we have a large scholarship programme for pupils. And for students who finish high school and have good grades in science and mathematics, we pay for busaries.

How do you assess the prospects for science in South Africa?

Adam: South African science has developed in different stages. In the beginning, astronomy actually became big here, but later science focused on our resources: agricultural research, mining science. When we industrialised after the Second World War, the prevailing view was that we should concentrate on research that would help the development of industry. During apartheid, the focus was on security research, nuclear technology and energy security. This is how competences in quite different fields have developed over the decades.

What was the situation after the end of apartheid?

Adam: Overall I am optimistic about science in South Africa. We have strong research institutions and above all good universities. You have to remember that we came out of a phase where the fight for human rights was at stake. And then we told the Finance Minister that we needed money for basic research. That was not easy to sell, given the development agenda in the 1990s and 2000s. But we managed to do so because we attracted a number of large projects such as SKA to our country, which touch on many interests. SKA concerns not only the Ministry of Science, but also the Ministries of Communications, International Relations and Trade. As soon as several ministries are interested in a matter, it becomes much easier to implement it. Platforms such as MeerKAT are advantageous in this respect, which can be used not only by South African research but also by an international scientific community: Then someone else pays the salaries of the scientists. Above all, we have to provide the technology.

Kramer: Our South African colleagues are now living the idea that the Max Planck Society also stands for. You never know what will come out of basic research. There may be major breakthroughs that change the world. Apart from that, it’s also about educating people. Not all of them are going to find a job in science. But young people learn here to solve problems that nobody has solved before, and they can bring that to the table in other places. This is another reason why basic research is so essential for every society and every economy. The South African colleagues have taken this very much to heart.

How do they assess the chance that basic research will become a motor for development in other countries of Southern Africa?

Adam: Basic research can mean very different things: There is basic research in agriculture or in genetics that is relevant to agriculture. But it will certainly be some time before we reach a research density in Southern Africa that is the basis of an innovation-driven economy. Even many better developed countries are not yet ready. And because the density of scientific activity is lower in developing countries, researchers there look less to industry next door rather than to that in the northern hemisphere. This makes the transfer to applications here even more difficult. Another problem with research’s contribution to economic development is that science often concentrates knowledge rather than disseminating it. Even the third industrial revolution, digitalization, which we hoped would make societies more democratic, did not succeed. No one has yet solved the problem of how to transform scientific knowledge into progress that benefits everyone. After all, there have been some breakthroughs in mining technology in South Africa that have created billions of dollars in global value creation. But when it comes to technology transfer, even in South Africa, we are not yet at the point where we would like to be.

Kramer: Of course, none of us believes that astronomy will solve the world’s problems, but we can help at least a little bit. Big Data, for example, is not only a problem for astronomy. But we may already have a little more experience in this field than other disciplines. When our S-band detectors are running, we will produce two petabytes of data every night, which cannot be stored anywhere. In general, the storage of data of any kind will in future account for a considerable proportion of global energy consumption. So we have to try to make computers greener. We are still lucky in South Africa: although MeerKAT is located in a rather remote area, we can simply connect it to the power grid. But for other parts of telescopes like SKA we may have to develop an independent renewable energy supply that is available around the clock.

See the full article here .

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Max Planck Institute for Radio Astronomy Bonn Germany.

MPIFR/Effelsberg Radio Telescope, in the Ahrgebirge (part of the Eifel) in Bad Münstereifel, Germany.

The Max Planck Institute for Radio Astronomy (German: Max-Planck-Institut für Radioastronomie) is located in Bonn, Germany. It is one of 80 institutes in the

From Harvard-Smithsonian Center for Astrophysics: “Astronomers Solve Mystery of How Planetary Nebulae Are Shaped”

From Harvard-Smithsonian Center for Astrophysics

September 17, 2020
Amy Oliver
Public Affairs
Center for Astrophysics | Harvard & Smithsonian
Fred Lawrence Whipple Observatory
520-879-4406
amy.oliver@cfa.harvard.edu

Gallery of stellar winds around cool aging stars, showing a variety of morphologies, including disks, cones, and spirals. The blue color represents material that is coming towards you, red ismaterial that is moving away from you. Image 8, in particular, shows the stellar wind of R Aquilae, which resembles the structure of rose petals. Credit: L. Decin, ESO/ALMA.

Following extensive observations of stellar winds around cool evolved stars scientists have figured out how planetary nebulae get their mesmerizing shapes. The findings, published in Science, contradict common consensus, and show that not only are stellar winds aspherical, but they also share similarities with planetary nebulae.

An international team of astronomers focused their observations on stellar winds—particle flows—around cool red giant stars, also known as asymptotic giant branch (AGB) stars. “AGB stars are cool luminous evolved stars that are in the last stages of evolution just before turning into a planetary nebula,” said Carl Gottlieb, an astronomer at the Center for Astrophysics | Harvard & Smithsonian, and a co-author on the paper. “Through their winds, AGB stars contribute about 85% of the gas and 35% of the dust from stellar sources to the Galactic Interstellar Medium and are the dominant suppliers of pristine building blocks of interstellar material from which planets are ultimately formed.”

Despite being of major interest to astronomers, a large, detailed collection of observational data for the stellar winds surrounding AGB stars—each made using the exact same method—was lacking prior to the study, which resulted in a long-standing scientific misconception: that stellar winds have an overall spherical symmetry. “The lack of such detailed observational data caused us to initially assume that the stellar winds have an overall spherical geometry, much like the stars they surround,” said Gottlieb. “Our new observational data shapes a much different story of individual stars, how they live, and how they die. We now have an unprecedented view of how stars like our Sun will evolve during the last stages of their evolution.”

Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile revealed something strange: the shape of the stellar winds didn’t conform with scientific consensus.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

“We noticed these winds are anything but round,” said Professor Leen Decin of KU Leuven University in Belgium, and the lead author on the paper. “Some of them are actually quite similar to planetary nebulae.” The new findings may have a significant impact on calculations of galactic and stellar evolution, most pointedly for the evolution of Sun-like stars. “Our findings change a lot,” said Decin. “Since the complexity of stellar winds was not accounted for in the past, any previous estimate of the mass-loss rate of old stars could be wrong by up to a factor of 10.”

The observations revealed many different shapes, further connecting stellar wind formation to that of planetary nebulae. “The winds we observed exhibit various shapes that are similar to planetary nebulae,” said Gottlieb. “Some are disk-like, while others are shaped like eyes, spiral structures, and even arcs.”

Astronomers quickly realized that the shapes weren’t formed randomly, and that companions—low-mass stars and heavy planets—in the vicinity of the AGB stars were influencing the shapes and patterns. “Just like a spoon that you stir in a cup of coffee with some milk can create a spiral pattern, the companion sucks material towards it as it revolves around the star and shapes the stellar wind,” said Decin. “All of our observations can be explained by the fact that the stars have a companion.”

In addition, the study provides a strong foundation for understanding Sun-like stars and the future of the Sun itself. “In about five billion years, the Sun will become more luminous,” said Gottlieb. “Its radius will expand to a length that is comparable to the current distance between the Sun and Earth, and it will enter the AGB phase.” Decin added, “Jupiter or even Saturn—because they have such a big mass—are going to influence whether the Sun spends its last millennia at the heart of a spiral, a butterfly or any of the other entrancing shapes we see in planetary nebulae today. Our current simulations predict that Jupiter and Saturn will create a weak spiral structure in the wind of the Sun once it is an AGB star.”

See the full article here .

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The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

From Caltech: “Radio Astronomy in the High Desert”

From Caltech

Summer 2020, Features
Whitney Clavin

The Long Wavelength Array of telescopes at Owens Valley, Altitude 1,222 m (4,009 ft).

Since 1958, astronomers have unveiled some of the deepest mysteries of the universe with the help of Caltech’s Owens Valley Radio Observatory (OVRO), located in high-desert terrain east of California’s Sierra Nevada mountains. The observatory, which remains at the forefront of radio astronomy, has seen many different projects come and go, including CARMA (Combined Array for Research in Millimeter-wave Astronomy), a hugely successful set of radio telescopes that ceased operations in 2015.

Combined Array for Research in Millimeter-wave Astronomy (CARMA), in the Inyo Mountains to the east of the Owens Valley Radio Observatory, at a site called Cedar Flat, 11,123 ft (3,390 m), ceased operations in 2015, relocated to Owens Valley Radio Observatory, Altitude 1,222 m (4,009 ft).

Now, several of those dishes are being repurposed at OVRO, and two other projects, the Deep Synoptic Array and the Long Wavelength Array (LWA), are in the midst of massive expansion efforts.

Caltech’s Deep Synoptic Array 10 dish array at Owens Valley Radio Observatory, near Big Pine, California USA, Altitude 1,222 m (4,009 ft).

“OVRO is experiencing a renaissance. We are moving radio astronomy in an entirely new direction,” says Gregg Hallinan, Caltech professor of astronomy and director of OVRO. “By building large numbers of small telescopes, we can scan the skies faster than ever before. These arrays will be generating more than 40 terabytes of science data per day, making them among the most data-intensive telescopes in the world.” The OVRO-LWA project was enabled by a donation from Deborah Castleman (MS ’86) and Harold Rosen (MS ’48, PhD ’51).

In Search of Magnetospheres

Marin Anderson (MS ’14, PhD ’19) and Michael Eastwood assemble antennas for the LWA.

The Long Wavelength Array (LWA) consists of hundreds of pyramid-shaped radio antennas that dot a vast stretch of OVRO. Since 2015, the LWA has used 250 antennas to probe the flickering of radio signals in the night skies, studying everything from the dawn of the universe, to outbursts on our sun, to glowing exoplanets. Now, the National Science Foundation (NSF) is funding an expansion of the project, bringing the total fleet of antennas to 352.

Hallinan is particularly excited for the project to search for signatures of magnetospheres around planets orbiting other stars. Magnetospheres are the regions around planets dominated by magnetic fields; Earth’s magnetic field protects its atmosphere from erosion by solar wind. The presence of magnetospheres on exoplanets may be a critical ingredient for planetary habitability but have eluded detection to date. “With the LWA, we will scan the entire sky every 10 seconds to monitor thousands of exoplanets simultaneously, waiting for a planet’s magnetosphere to light up in radio waves,” says Hallinan.

Staring at the Whole Sky

OVRO hosts several small, focused experiments that target high-risk, high-reward science. A notable example is STARE2 (Survey for Transient Astronomical Radio Emission 2), led by Shri Kulkarni, the George Ellery Hale Professor of Astronomy and Planetary Science at Caltech. The project consists of three radio receivers located at OVRO; at NASA’s Deep Space Network facility in Goldstone, California; and at Delta, Utah.
The receivers scan broad swaths of the sky every night in search of the brightest fast radio bursts (FRBs). While the receivers are not as sensitive as radio dishes, what they lose in sensitivity, they gain in field of view. In April of this year, STARE2 detected what may be the first-ever FRBs seen in the Milky Way galaxy. The results are preliminary but may provide long-sought proof that FRBs are caused by erupting magnetars, a type of exotic star with powerful magnetic fields.

Many, Many Dishes

The night skies flash with intense radio pulses, called fast radio bursts (FRBs), whose causes have remained unclear. One key to unlocking the mystery of these bursts is to identify the galaxies from which they originate. In 2019, the Deep Synoptic Array-10 (DSA-10) at OVRO identified one such host galaxy of an FRB, a rare feat made even more difficult by the fact that this particular FRB did not repeat, as others have been known to do. Now, thanks to new funding from the National Science Foundation (NSF), the DSA is in the midst of a major upgrade, expanding from 10 to 110 radio dishes. The DSA-110 is expected to begin observations in October of this year. “When we begin, we will be identifying about two FRB host galaxies per week,” says Vikram Ravi, assistant professor of astronomy. “That’s a massive sample of galaxies and will help us reveal FRBs’ true nature.” In the future, the DSA will get an even more dramatic upgrade with plans to expand to 2,000 radio dishes. A project funded by Schmidt Futures, called the Radio Camera Initiative, will allow the DSA-2000 to produce images in real time, a first for radio telescopes. According to Ravi, this will make the DSA-2000 “the most powerful radio telescope ever built.”

Wendy Chen, Nitika Yadlapalli, and Corey Posner assemble a DSA dish.

A New Purpose

CARMA [above] , which operated from 2005 to 2015, was one of the most powerful millimeter-wave telescope arrays in the world. (Millimeter waves are considered a type of radio wave.) Located in the Inyo Mountains near Owens Valley, the array consisted of antennas brought together from telescopes across the U.S. to create a combined array of much greater sensitivity. These antennas included the Leighton dishes, named for the late Caltech professor Robert Leighton (BS ’41, MS ’44, PhD ’47), who designed them in the 1970s to kickstart millimeter astronomy at OVRO. After the closure of CARMA, the Leighton dishes were moved back to OVRO. COMAP, which stands for CO Mapping Array Pathfinder, is one of the projects that is repurposing a Leighton dish. Begun in the summer of 2018, this project, led by OVRO associate director Kieran Cleary and professor emeritus Tony Readhead, traces the evolution of galaxies by mapping carbon monoxide (CO), a marker of faint faraway galaxies that are otherwise hard to see. A few of the Leighton dishes are also being combined to form a robotic instrument, known as SPRITE, to determine the nature of some of the most energetic explosions in the universe.

Another project for which a Leighton dish is being redeployed is the Event Horizon Telescope (EHT), which, in 2019, famously harnessed the power of several radio observatories across the globe to create the first-ever picture of a black hole. Now, with the help of new funding from the NSF, the EHT project is tapping into even more radio telescopes to better image and study black holes. “Adding a telescope dish at Owens Valley fills a critical hole in the EHT’s virtual Earth-sized telescope,” says Katherine L. (Katie) Bouman, an assistant professor of computing and mathematical sciences and electrical engineering who leads the Caltech portion of the international EHT team.

Now iconic image of Katie Bouman-Harvard Smithsonian Astrophysical Observatory after the image of Messier 87 was achieved. Headed from Harvard to Caltech as an Assistant Professor. On the committee for the next iteration of the EHT .

Katie Bouman of Harvard Smithsonian Observatory for Astrophysics, headed to Caltech, with EHT hard drives from Messier 87

Messier 87*, The first image of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Image via JPL/ Event Horizon Telescope Collaboration.

“This brings us much closer to one day capturing a movie that allows us to track the gas falling into a black hole over the course of a single night.”

See the full article here .

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The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

Caltech campus

From phys.org: “Radio relic discovered in a nearby galaxy cluster”

From phys.org

September 15, 2020
Tomasz Nowakowski

MeerKAT radio contours (magenta) on A2384 XMM-Newton image. Credit: Parekh et al., 2020.

Using the MeerKAT radio telescope in South Africa, an international team of astronomers has detected a radio relic in a nearby, low-mass, merging galaxy cluster designated A2384.

SKA SARAO Meerkat telescope, South African design.

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

The finding is reported in a research paper published September 6 on the arXiv pre-print repository and accepted in MNRAS.

Radio relics are diffuse, elongated radio sources of synchrotron origin. They occur in the form of spectacular single or double symmetric arcs at the peripheries of galaxy clusters. Astronomers are especially interested in searching for such sources in merging galaxy clusters, as the number of radio relics associated with merger shocks is still small.

At redshift of 0.092, A2384 is a nearby, low-mass (about 261 trillion solar masses), complex cluster of galaxies. It consists of two components, designated A2384(N) and A2384(S), showcasing a dense X-ray filament between them, estimated to be around 2.3 million light years long.

A group of astronomers led by Viral Parekh of the Rhodes University in Makhanda, South Africa, observed A2384 with MeerKAT in May 2019. They identified an extended radio source located at the edge of the galaxy cluster that turned out to be a single radio relic.

“In our MeerKAT images, we discovered an extended radio source at the bottom of the A2384(S) cluster,” the researchers wrote in the paper.

The newly found radio source is located perpendicular to the A2384 merger axis, extending from the south-east to the north-west. Its dimensions are approximately 2.7 by 0.86 million light years and the radio power of the source at 1.4 GHz was measured to be 387 million PW/Hz. The astronomers noted that the geometry, location and size of this source indicate that it is a radio relic associated with merger shock and the A2384 cluster.

Furthermore, the MeerKAT data reveal that the relic in A2384 is a very steep spectrum source, between 941-1454 MHz, with spectral index at a level of about -2.5. This, according to the authors of the paper, suggest the re-acceleration of the pre-relativistic electrons in the presence of the merger shock.

Trying to explain the origin of this radio relic, the astronomers assume that it is most likely the result of shock wave propagation during the passage of the low-mass A2384(S) cluster through the massive A2384(N) cluster. This may create a trail seen as a hot X-ray filament between the cluster’s two components.

“During the interaction of the clusters, sub-cluster A2384(S) has passed through A2384(N) and is likely to have removed a large amount of hot gas (and a number of galaxies) from both systems in the direction of the merger,” the researchers explained.

Besides the detection of the radio relic in A2384, Parekh’s team also found a candidate radio ridge in the cluster’s X-ray filament. The ridge is relatively small (about 590,000 by 420,000 light years) and the astronomers suppose that it could be a new class of radio source situated between the two components of A2384.

See the full article here .

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About Science X in 100 words
Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
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From National Radio Astronomy Observatory: “IMAGE RELEASE: A Galaxy’s Stop-and-Start Young Radio Jets”

From National Radio Astronomy Observatory

August 25, 2020
Media Contact:
Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu

Credit: Lister et al.; Sophia Dagnello, NRAO/AUI/NSF.

In this image, made with the National Science Foundation’s Very Long Baseline Array (VLBA) [below], young, radio-emitting jets of material emerge from the core of an elliptical galaxy some 500 million light-years from Earth. After NASA’s Fermi Gamma-ray Space Telescope detected high-energy gamma rays coming from the object, scientists used the VLBA to make high-resolution images of the galaxy, dubbed TXS 0128+554.

NASA/Fermi LAT.

NASA/Fermi Gamma Ray Space Telescope.

This image is a composite of six VLBA images made at observing frequencies ranging from 2.2 GigaHertz (GHz) to 22.2 GHz. The broad lobes on either side of the bright core are the result of jet activity that began roughly 80 years ago. The gap between these lobes and the central region indicates, the scientists said, that the jet activity stopped sometime after that, then resumed about 10 years ago.

“These are among the youngest known jets in such systems, and only a handful are known to emit gamma-rays,” said Matthew Lister, of Purdue University.

The bright edges of the lobes are where the ejected material, moving at about a third the speed of light, impacted material within the galaxy. The bright emitting areas total about 35 light-years across, and are at the core of the galaxy, where a supermassive black hole about one million times the mass of the Sun resides.

Lister and his colleagues are reporting their findings in The Astrophysical Journal.

See the full article here .

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NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

NRAO ngVLA, located near the location of the VLA site on the plains of San Agustin, fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico

NRAO/VLBA

ESO/NRAO/NAOJ 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.

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 ALMA: “ALMA Discovers Misaligned Rings in Planet-Forming Disk Around Triple Stars”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

From ALMA

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Iris Nijman
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Cell phone: +1 (434) 249 3423
Email: alma-pr@nrao.edu

ALMA and the SPHERE instrument on ESO’s Very Large Telescope have imaged GW Orionis, a triple star system with a peculiar inner region.

ESO SPHERE extreme adaptive optics system and coronagraphic facility on the extreme adaptive optics system and coronagraphic facility on the VLT MELIPAL UT3, Cerro Paranal, Chile, with an elevation of 2,635 metres (8,645 ft) above sea level.

ESO SPHERE extreme adaptive optics system and coronagraphic facility on the extreme adaptive optics system and coronagraphic facility on the VLT MELIPAL UT3, Cerro Paranal, Chile, with an elevation of 2,635 metres (8,645 ft) above sea level.

ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
•KUEYEN (UT2; The Moon ),
•MELIPAL (UT3; The Southern Cross ), and
•YEPUN (UT4; Venus – as evening star).
elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo.

Unlike the flat planet-forming discs we see around many stars, GW Orionis features a warped disc, deformed by the movements of the three stars at its centre. This composite image shows both the ALMA and SPHERE observations of the disc by Kraus et al. The ALMA image (blue) shows the disc’s ringed structure, with the innermost ring (part of which is visible as an oblong dot at the very centre of the image) separated from the rest of the disc. The SPHERE observations (orange-red) allowed astronomers to see for the first time the shadow of this innermost ring on the rest of the disc, which made it possible for them to reconstruct its warped shape. Credit: ALMA (ESO/NAOJ/NRAO), ESO/Exeter/Kraus et al.

Representation of the disc structure and stellar orbit of the GW Orionis triple system, as derived from the ALMA and VLT observations by Kraus et al. Orange rings are the (misaligned) rings seen by ALMA. The transparent surfaces correspond to the lower-density dust filaments that connect the rings and that dominate the emission in scattered light. Credit: Kraus et al., 2020; NRAO/AUI/NSF.

ALMA images of the planet-forming disk with misaligned rings around triple star system GW Orionis. The image on the right is made with ALMA data taken in 2017 from Bi et al. The image on the left is made with ALMA data taken in 2018 from Kraus et al. Credit: ALMA (ESO/NAOJ/NRAO), S. Kraus & J. Bi; NRAO/AUI/NSF, S. Dagnello.

Using the Atacama Large Millimeter/submillimeter Array (ALMA), two teams of astronomers have for the first time discovered a planet-forming disk with misaligned rings around a triple star system, called GW Orionis. The astronomers give two possible scenarios for the misalignment: either the disk was torn apart by the gravitational pull from the stars, or by a newborn planet.

Most stars that look like our Sun are born with siblings. Unlike the planets in our Solar System, which all orbit in the same plane around the Sun, planets around these multi-star systems often have orbits that are not aligned with the orbits of their stars. Their crooked orbits originate in the planet-forming disks, the birthplaces of planets. Studying misaligned disks around multiple stars therefore helps us understand how these planets form (Previously ALMA imaged the misaligned disks in the ‘Tatooine’ binary star system).

In a new study, two independent teams of astronomers pointed ALMA at GW Orionis. This is a young star system hosting three stars. The inner stars GW Ori A and B orbit each other and are separated by 1 au, and the third star GW Ori C orbits its two siblings at a distance of roughly 8 au.

ALMA found three separate rings with different orientations in the massive planet-forming disk of GW Orionis, located roughly 46, 185, and 340 au from its center. The inner ring is very misaligned relative to both the outer rings and the three stars. The outermost ring is the largest ever observed in planet-forming disks. If a planet would be forming in the gap between the inner and outer ring, it would be located incredibly far away from the stars. For comparison, Neptune is only about 30 au from the Sun.

ALMA observed the misalignment in the rings of GW Orionis for the first time in 2017. “We were surprised to see the strong misalignment of the inner ring,” said Jiaqing Bi of the University of Victoria in Canada, and leader of the team that published their results in the The Astrophysical Journal Letters in May this year. “But the strange warp in the disk is confirmed by a twisted pattern that ALMA measured in the gas of the disk.”

The second team of astronomers, led by Stefan Kraus from the University of Exeter in the UK, pointed both ALMA and the European Southern Observatory’s Very Large Telescope (VLT) towards the triple stars. His team detected warm gas at the inner edge of the misaligned ring and scattered light from the warped surface of the disk.

“In our images, we see the shadow of the inner ring on the outer disk. At the same time, ALMA allowed us to measure the precise shape of the ring that casts the shadow. Combining this information allows us to derive the 3-dimensional orientation of the misaligned ring and of the warped disk surface,” said Kraus, whose team published their results in Science today.

Using telescope arrays operating at infrared wavelengths, they also mapped the orbits of the three stars for over 11 years, covering a full orbital period. The team found that the three stars do not orbit in the same plane, but that they are misaligned with respect to each other and with respect to the disk. “This proved crucial to understand how the stars shape the disk,” added team member John Monnier of the University of Michigan.

Both teams performed computer simulations to investigate what could possibly cause the inner ring to be misaligned from the rest of the disk and the stars.

Kraus and his team link the observed misalignments to the ‘disk-tearing effect’, which suggests that the gravitational pull of stars in different planes can warp and break their disks. Their simulations showed that the misalignment in the orbits of the three stars could cause the disk around them to break into distinct rings.

The simulations by Bi and his team hint at another possible explanation for the large misalignment between the inner and middle dust rings. “Our simulations show that the gravitational pull from the triple stars alone cannot explain the observed large misalignment. We think that the presence of a planet between these rings is needed to explain why the disk was torn apart,” said team member Nienke van der Marel of the University of Victoria. “This planet has likely carved a dust gap and broken the disk at the location of the current inner and outer rings,” she added.

Kraus also speculates about planets in GW Orionis: “The inner ring contains enough dust to build 30 Earths, which is sufficient for a planet to form in the ring.”

If future studies find this exotic planet – whether it already exists or is still forming – it would be the first planet ever observed to orbit three stars, and it would possess a very unusual orbit.

See the full article here .

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

From Sky & Telescope: “Twinkling Quasar Hints at Mysterious Nearby Plasma Cloud”

From Sky & Telescope

September 1, 2020
Govert Schilling

Radio observations have turned up evidence of a cloud of hot plasma near — or even in — the solar system. But its distance estimate is still up for debate.

Discovery radio image of the new rapidly twinkling quasar J1402+5347 (bottom); the spiral galaxy M101 is at the top. The radial spikes are an artifact caused by the source’s rapid variability in combination with the east-west orientation of the Westerbork interferometer. Credit: Tom Oosterloo / ASTRON.

Radio astronomers have detected a cloud of hot plasma at the edge of the solar system, and no one has a clue about its nature or origin.

Researchers didn’t observe the mystery cloud directly. Instead, they saw its effect on the radio waves of a background quasar known as J1402+5347. Its presence caused the quasar’s light to flicker on a timescale of minutes. “It’s a spectacular twinkler, and a very nice surprise,” says Mark Walker (Manly Astrophysics, Australia), who studies intra-hour variability of quasars but wasn’t involved in the new work.

Until recently, astronomers knew of three rapidly twinkling quasars, whose scintillations suggested the presence of plasma clouds at distances of a few tens of light-years. But the new cloud is much closer, says study lead Tom Oosterloo (ASTRON Netherlands Institute for Radio Astronomy).

Interstellar radio scintillation produces a speckle pattern, comparable to the speckle pattern in the optical image of a star that results from atmospheric turbulence. As Earth moves through that pattern, astronomers observe rapid brightness variations. “From the observed twinkle frequency of J1402+5347,” Oosterloo says, “we deduce a distance of just 0.8 light-years for the plasma screen, which is within the solar system’s Oort cloud.”

Schematic of radio waves from a quasar traveling through a plasma cloud and arriving at Apertif.
ASTRON / Credit: Studio Eigen Merk.

The discovery is the first published scientific result obtained with the new wide-angle Apertif receivers (Aperture Tile In Focus) on ASTRON’s venerable 14-dish Westerbork Synthesis Radio Telescope. Apertif increased the instrument’s field of view by a factor of 40, making it much easier to find rare sources.

The plasma cloud, thought to be at least a few billion kilometers (several astronomical units) across, could be an interloper from interstellar space. Or it could be some kind of remnant from the formation of the solar system, says Oosterloo. “That would be really exciting.”

However, Walker isn’t so sure about the cloud’s estimated proximity, which is based on a simple, idealized model. Each of the previously known twinkling quasars appeared to be associated with a nearby hot star (Vega, Spica, and Alhakim or Iota Centauri, respectively), suggesting that the intervening plasma was somehow expelled by the star.

As Oosterloo and his colleagues discuss in their Astronomy & Astrophysics paper, the new quasar’s sky position is close to Alkaid (Eta Ursae Majoris), which is just over 100 light-years from Earth. “It’s very unlikely that we’d get a random coincidence between [a twinkler] and a hot star like Alkaid,” says Walker. “The chances are less than one in 1,000 for a match as close as this — so my guess is that they are indeed physically related.”

Some of the fourteen 25-meter dishes of the Westerbork Synthesis Radio Telescope in the Netherlands. The white boxes in the focal points of the antennas contain the new wide-angle Apertif receivers. Credit:
ASTRON.

But according to Oosterloo, that would imply an improbably compact and extremely elongated plasma cloud. Moreover, since the team serendipitously found the new intra-hour variable quasar in April 2019, they’ve discovered 10 more of these rare sources that do not seem to be associated with nearby stars, though the intervening plasma appears to be many light-years away in these newer cases.

Radio astronomer Hayley Bignall (CSIRO, Australia), who was also not involved in the new study, says she would “naively agree with the arguments the authors make for a very nearby plasma screen. On its own, I would say the case for the very small distance is compelling, but not 100% convincing.” Follow-up observations at other wavelengths and the study of additional twinkling quasars would help strengthen or refute the claim, Bignall says.

See the full article here .

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Sky & Telescope magazine, founded in 1941 by Charles A. Federer Jr. and Helen Spence Federer, has the largest, most experienced staff of any astronomy magazine in the world. Its editors are virtually all amateur or professional astronomers, and every one has built a telescope, written a book, done original research, developed a new product, or otherwise distinguished him or herself.

Sky & Telescope magazine, now in its eighth decade, came about because of some happy accidents. Its earliest known ancestor was a four-page bulletin called The Amateur Astronomer, which was begun in 1929 by the Amateur Astronomers Association in New York City. Then, in 1935, the American Museum of Natural History opened its Hayden Planetarium and began to issue a monthly bulletin that became a full-size magazine called The Sky within a year. Under the editorship of Hans Christian Adamson, The Sky featured large illustrations and articles from astronomers all over the globe. It immediately absorbed The Amateur Astronomer.

Despite initial success, by 1939 the planetarium found itself unable to continue financial support of The Sky. Charles A. Federer, who would become the dominant force behind Sky & Telescope, was then working as a lecturer at the planetarium. He was asked to take over publishing The Sky. Federer agreed and started an independent publishing corporation in New York.

“Our first issue came out in January 1940,” he noted. “We dropped from 32 to 24 pages, used cheaper quality paper…but editorially we further defined the departments and tried to squeeze as much information as possible between the covers.” Federer was The Sky’s editor, and his wife, Helen, served as managing editor. In that January 1940 issue, they stated their goal: “We shall try to make the magazine meet the needs of amateur astronomy, so that amateur astronomers will come to regard it as essential to their pursuit, and professionals to consider it a worthwhile medium in which to bring their work before the public.”

From ALMA via phys.org: “Molecular outflow identified in the galaxy NGC 1482”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

From ALMA

via

From phys.org

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory Santiago – Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Iris Nijman
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Cell phone: +1 (434) 249 3423
Email: alma-pr@nrao.edu

by Tomasz Nowakowski

ALMA CO (1–0) integrated intensity image of NGC 1482 with KS-band (2MASS) brightness contours in the central region. Credit: Salak et al., 2020.

Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, Altitude 2,606 m (8,550 ft) and at the Cerro Tololo Inter-American Observatory at an altitude of 2200 meters near La Serena, Chile.

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers from Japan have probed a nearby starburst galaxy known as NGC 1482. They detected a molecular gas outflow that could be essential to improving the understanding of the galactic wind in NGC 1482. The finding is detailed in a paper published August 20 on arXiv.org [The Astrophysical Journal].

Galaxy-scale outflows of gas, dubbed galactic winds, are driven by star formation or radiation from active galactic nuclei (AGN). Observations show that such winds can transport metal-enriched interstellar material into the circumgalactic (CGM) and intergalactic medium (IGM). Therefore, studies of these outflows can provide crucial insights into the process of star formation and the growth of supermassive black holes (SMBHs) in galaxies.

At a distance of about 63.9 million light years, NGC 1482 is an early-type galaxy in the Eridanus group of galaxies. It has a central bulge surrounded by a gaseous disk (dust lane), and a warm ionized gas extending perpendicular to the disk.

Recently, a team of astronomers led by Dragan Salak of the University of Tsukuba, Japan, investigated the ionized gas of NGC 1482 by conducting high-resolution observations of this galaxy with ALMA. The observational campaign delivered important information about the distribution and dynamics of molecular gas in the studied object.

“In this article, we have presented the first high-resolution observations of molecular gas traced by CO (1–0) and the discovery of a molecular outflow in the nearby starburst galaxy NGC 1482,” the astronomers wrote in the paper.

ALMA observations found that molecular gas in NGC 1482 is distributed in a nearly edge-on disk with an inclination of 76 degrees and a radius of about 9,800 light years. The outflow appears to be extending at least 4,900 light years perpendicular to the disk. The astronomers say that this is the first detection of a molecular wind in NGC 1482.

The base of the molecular outflow is the 100 GHz continuum emission with a radius of approximately 3,260 light years. The researchers managed to derive a star-formation rate (SFR) for the central starburst region of NGC 1482 from the continuum flux density. According to the study, the SFR for this area is at a level of about 4.0 solar masses per year.

Furthermore, the total molecular gas mass of NGC 1482 was calculated to be some 2.7 billion solar masses and the outflow mass was estimated to be around 70 million solar masses. The molecular wind velocity is approximately 100 km/s, while the kinetic energy and momentum of the wind were found to be about 1% and 20% of the initial energy and momentum released by supernova explosions in the central region of the galaxy. Given that there is no evidence of an AGN in NGC 1482, the researchers concluded that the wind in this galaxy is driven by starburst feedback.

In addition, the results suggest that NGC 1482 has experienced a tidal interaction with its neighboring galaxy, NGC 1481. Hence, the authors of the paper assume that the starburst and superwind in NGC 1482 were triggered by tidal interaction. This led to a rapid supply of neutral gas into the galactic central region.

See the full article here.

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

From National Astronomical Observatory of Japan: “Can Black Hole Fire Up Cold Heart of the Phoenix?”

From National Astronomical Observatory of Japan

August 31, 2020

Artist’s illustration of the structures seen in the observations. (Credit: NAOJ.)

Radio astronomers have detected jets of hot gas blasted out by a black hole in the galaxy at the heart of the Phoenix Galaxy Cluster, located 5.9 billion light-years away in the constellation Phoenix. This is an important result for understanding the coevolution of galaxies, gas, and black holes in galaxy clusters.

Galaxies are not distributed randomly in space. Through mutual gravitational attraction, galaxies gather together to form collections known as clusters. The space between galaxies is not entirely empty. There is very dilute gas throughout a cluster which can be detected by X-ray observations.

If this intra-cluster gas cooled, it would condense under its own gravity to form stars at the center of the cluster. However, cooled gas and stars are not usually observed in the hearts of nearby clusters, indicating that some mechanism must be heating the intra-cluster gas and preventing star formation. One potential candidate for the heat source is jets of high-speed gas accelerated by a super-massive black hole in the central galaxy.

The Phoenix Cluster is unusual in that it does show signs of dense cooled gas and massive star formation around the central galaxy. This raises the question, “does the central galaxy have black hole jets as well?”

A team led by Takaya Akahori at the National Astronomical Observatory of Japan used the Australia Telescope Compact Array (ATCA) to search for black hole jets in the Phoenix Galaxy Cluster with the highest resolution to date.

Australian Telescope Compact Array, an array of six 22-m antennas, at the Paul Wild Observatory, 25 km west of the town of Narrabri in rural New South Wales.

They detected matching structures extending out from opposite sides of the central galaxy. Comparing with observations of the region taken from the Chandra X-ray Observatory archive data shows that the structures detected by ATCA correspond to cavities of less dense gas, indicating that they are a pair of bipolar jets emitted by a black hole in the galaxy. Therefore, the team discovered the first example, in which intra-cluster gas cooling and black hole jets coexist, in the distant Universe.

Further details of the galaxy and jets could be elucidated through higher-resolution observations with next generation observational facilities, such as the Square Kilometre Array scheduled to start observations in the late 2020s.

These results appeared as T. Akahori et al. Discovery of radio jets in the Phoenix galaxy cluster center in the August 2020 issue of Publications of the Astronomical Society of Japan.

Radio observations of the center of the Phoenix Galaxy Cluster showing jet structures extending out from the central galaxy. (Credit: Akahori et al.)

See the full article here .

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The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation 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, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

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

ESO/NRAO/NAOJ ALMA Array

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