From Science News: “Brett McGuire searches space for the chemistry of life”

From Science News

October 2, 2019
Lisa Grossman

Cosmic molecules may point to the origins of carbon-based life.

In a different reality, space might smell like almonds. After all, scientists surveying the chemicals in the cosmos have found benzonitrile; just a bit of the compound would fill your nostrils with a bitter almond scent.

But our cosmos is too vast. “Space smells like nothing,” says astrochemist Brett McGuire. “There’s not enough to get an actual whiff.”

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Astrochemist Brett McGuire combines skills in chemistry and astronomy to search for complex molecules in space. Courtesy of B. McGuire

McGuire, 32, of the National Radio Astronomy Observatory in Charlottesville, Va., confirmed the presence of benzonitrile in a dark cloud in the Milky Way. He also discovered some of the other most complex molecules in space to date. By figuring out which molecules are out there, he and others hope to learn how the organic chemistry that undergirds all life on Earth — and perhaps anywhere else in the universe — gets started in space.

McGuire got his start in space as an undergraduate chemistry major at the University of Illinois at Urbana-Champaign. During a talk, Ben McCall, now a sustainability expert at the University of Dayton in Ohio, explained what he does for a living. He said something like, “I blow shit up, torture it with lasers and then I look for it in space,” McGuire recalls.

Enough said. McGuire spent that summer working in McCall’s lab, building a spectrometer to study how hydrogen gas, H2, reacts with H3+ — three hydrogen atoms with only two electrons. Some of McCall’s research included zapping gases of simple molecules with electricity — “an actual miniature lightning bolt,” McGuire says — to force atoms to recombine into new compounds that can’t be bought in a bottle.

“Brett was a very precocious young scientist,” McCall says. “This was the only time I’ve had a student who really started a new instrument from scratch as an undergrad.”

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The discovery of benzonitrile in a dust cloud in the Milky Way suggests that complex molecules can form from the buildup of smaller molecules in space. (Carbon is black, hydrogen white and nitrogen blue.) Ben Mills and Jynto/Wikimedia Commons

Because space is so big and mostly empty, at least by Earth standards, it can take millions of years for two molecules flying around like billiard balls to get close enough to interact. “But it’s not just neutral billiard balls out there,” McGuire says. A charged molecule, like H3+, which has been discovered in interstellar space, can pull other molecules closer. “More or less all chemistry in space can trace itself back to H3+ at some point.”

And all that chemistry includes some tantalizingly lifelike stuff. In 2016, McGuire and colleagues reported discovering propylene oxide in a gas cloud within the Milky Way.

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MOLECULE CLUE A gas cloud (Sagittarius B2) near the center of the galaxy (Sagittarius A*) is loaded with propylene oxide, a molecule that comes in mirror-image configurations. B. Saxton, NRAO/AUI/NSF from data provided by N.E. Kassim, Naval Research Laboratory, Sloan Digital Sky Survey.

That was the first molecule seen in space that, like the amino acids that make up proteins and are essential to life on Earth, has two forms that are mirror images of each other. Large rings of carbon and hydrogen, called polycyclic aromatic hydrocarbons, or PAHs, have also been spotted around dead or dying stars — though it’s been hard to tell how many carbons and hydrogens the PAHs contain.

PAHs are thought to be the seeds of dust, planets and organic chemistry in our galaxy and other galaxies, McGuire says. So how do they form? “How do you go from H3+ to things that literally click together to make the building blocks of life?” he asks.

The work of enumerating what’s out there mostly takes place in a lab on Earth. McGuire injects a puff of gas of the molecule he’s interested in into a large vacuum chamber, where the low temperature and pressure make the gas expand. Then he hits the gas with a pulse of intense microwave or radio radiation, sending the molecules tumbling. As they tumble, the molecules emit photons at a specific frequency. That light signature, called the molecule’s rotational spectrum, is what McGuire looks for when he searches for those molecules in space.

Once McGuire knows the molecular fingerprint he’s after, he turns to radio telescopes to find the same print in space. Many scientists focus on one branch of this process or the other, the laboratory spectroscopy or the interstellar astronomy; only a few have expertise in both. “Brett is one of those very few people,” McCall says.

To sniff almonds in space, McGuire and colleagues focused the Robert C. Byrd Green Bank Telescope in West Virginia on TMC-1, a dark cloud about 450 light-years from Earth “where maybe there are stars that are considering starting to form,” McGuire says. Forty hours of observing confirmed that benzonitrile, a benzene ring with a cyanide molecule stuck on the end, was there [Science].

Green Bank Radio Telescope, West Virginia, USA, now the center piece of the GBO, Green Bank Observatory, being cut loose by the NSF

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Scientists have detected complex molecules in TMC-1, a stellar nursery in the Milky Way. The cloud lacks big, bright stars, and its dust grains glow only faintly (shown in orange). ESO

Lately, McGuire and colleagues are closing in on a bigger prize: specific PAHs in the space between stars. Knowing the makeup of PAHs in space will help reveal how they click together from smaller molecules, McGuire says. Finding these molecules would show that advanced chemistry is happening, in some cases before stars begin forming.

Benzonitrile and the more complex molecules it hints at are “the first clear marker” of carbon-based chemistry in space, says Ryan Fortenberry, an astrochemist at the University of Mississippi in Oxford who wasn’t involved in the benzonitrile finding. “Before this, we were just kind of wandering around in the wilderness,” Fortenberry says. “Now we have found the trail.”

See the full article here .


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From ALMA via NRAO: “ALMA Dives into Black Hole’s ‘Sphere of Influence’”

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

From ALMA

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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

Calum Turner
ESO Assistant Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: calum.turner@eso.org

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
Email: cblue@nrao.edu

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Credit: ALMA (ESO/NAOJ/NRAO), B. Boizelle; NRAO/AUI/NSF, S. Dagnello; Hubble Space Telescope (NASA/ESA); Carnegie-Irvine Galaxy Survey

ALMA has made the most precise measurements of cold gas swirling around a supermassive black hole — the cosmic behemoth at the center of the giant elliptical galaxy NGC 3258. The multi-color ellipse reflects the motion of the gas orbiting the black hole, with blue indicating motion toward us and red motion away from us. The inset box represents how the orbital velocity changes with distance from the black hole. The material was found to rotate faster the closer in the astronomers observed to the black hole, enabling them to accurately calculate its mass: a whopping 2.25 billion times the mass of our Sun.

What happens inside a black hole stays inside a black hole, but what happens inside a black hole’s “sphere of influence” – the innermost region of a galaxy where a black hole’s gravity is the dominant force – is of intense interest to astronomers and can help determine the mass of a black hole as well as its impact on its galactic neighborhood.

New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) provide an unprecedented close-up view of a swirling disk of cold interstellar gas rotating around a supermassive black hole. This disk lies at the center of NGC 3258, a massive elliptical galaxy about 100 million light-years from Earth. Based on these observations, a team led by astronomers from Texas A&M University and the University of California, Irvine, have determined that this black hole weighs a staggering 2.25 billion solar masses, the most massive black hole measured with ALMA to date.

Though supermassive black holes can have masses that are millions to billions of times that of the Sun, they account for just a small fraction of the mass of an entire galaxy. Isolating the influence of a black hole’s gravity from the stars, interstellar gas, and dark matter in the galactic center is challenging and requires highly sensitive observations on phenomenally small scales.

“Observing the orbital motion of material as close as possible to a black hole is vitally important when accurately determining the black hole’s mass.” said Benjamin Boizelle, a postdoctoral researcher at Texas A&M University and lead author on the study appearing in The Astrophysical Journal. “These new observations of NGC 3258 demonstrate ALMA’s amazing power to map the rotation of gaseous disks around supermassive black holes in stunning detail.”

Astronomers use a variety of methods to measure black hole masses. In giant elliptical galaxies, most measurements come from observations of the orbital motion of stars around the black hole, taken in visible or infrared light. Another technique, using naturally occurring water masers (radio-wavelength lasers) in gas clouds orbiting around black holes, provides higher precision, but these masers are very rare and are associated almost exclusively with spiral galaxies having smaller black holes.

During the past few years, ALMA has pioneered a new method to study black holes in giant elliptical galaxies. About 10 percent of elliptical galaxies contain regularly rotating disks of cold, dense gas at their centers. These disks contain carbon monoxide (CO) gas, which can be observed with millimeter-wavelength radio telescopes.

By using the Doppler shift of the emission from CO molecules, astronomers can measure the velocities of orbiting gas clouds, and ALMA makes it possible to resolve the very centers of galaxies where the orbital speeds are highest.

“Our team has been surveying nearby elliptical galaxies with ALMA for several years to find and study disks of molecular gas rotating around giant black holes,” said Aaron Barth of UC Irvine, a co-author on the study. “NGC 3258 is the best target we’ve found, because we’re able to trace the disk’s rotation closer to the black hole than in any other galaxy.”

Just as the Earth orbits around the Sun faster than Pluto does because it experiences a stronger gravitational force, the inner regions of the NGC 3258 disk orbit faster than the outer parts due to the black hole’s gravity. The ALMA data show that the disk’s rotation speed rises from 1 million kilometers per hour at its outer edge, about 500 light-years from the black hole, to well over 3 million kilometers per hour near the disk’s center at a distance of just 65 light-years from the black hole.

The researchers determined the black hole’s mass by modeling the disk’s rotation, accounting for the additional mass of the stars in the galaxy’s central region and other details such as the slightly warped shape of the gaseous disk. The clear detection of rapid rotation enabled the researchers to determine the black hole’s mass with a precision better than one percent, although they estimate an additional systematic 12 percent uncertainty in the measurement because the distance to NGC 3258 is not known very precisely. Even accounting for the uncertain distance, this is one of the most highly precise mass measurements for any black hole outside of the Milky Way galaxy.

“The next challenge is to find more examples of near-perfect rotating disks like this one so that we can apply this method to measure black hole masses in a larger sample of galaxies,” concluded Boizelle. “Additional ALMA observations that reach this level of precision will help us better understand the growth of both galaxies and black holes across the age of the universe.”

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.

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From National Radio Astronomy Observatory: “New Method May Resolve Difficulty in Measuring Universe’s Expansion”

From National Radio Astronomy Observatory

Astronomers using National Science Foundation (NSF) radio telescopes have demonstrated how a combination of gravitational-wave and radio observations, along with theoretical modeling, can turn the mergers of pairs of neutron stars into a “cosmic ruler” capable of measuring the expansion of the Universe and resolving an outstanding question over its rate.

The astronomers used the NSF’s Very Long Baseline Array (VLBA), the Karl G. Jansky Very Large Array (VLA) and the Robert C. Byrd Green Bank Telescope (GBT) to study the aftermath of the collision of two neutron stars that produced gravitational waves detected in 2017.

NRAO/VLBA

NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

Green Bank Radio Telescope, West Virginia, USA, now the center piece of the GBO, Green Bank Observatory, being cut loose by the NSF

This event offered a new way to measure the expansion rate of the Universe, known by scientists as the Hubble Constant. The expansion rate of the Universe can be used to determine its size and age, as well as serve as an essential tool for interpreting observations of objects elsewhere in the Universe.

Two leading methods of determining the Hubble Constant use the characteristics of the Cosmic Microwave Background, the leftover radiation from the Big Bang, or a specific type of supernova explosions, called Type Ia, in the distant Universe. However, these two methods give different results.

“The neutron star merger gives us a new way of measuring the Hubble Constant, and hopefully of resolving the problem,” said Kunal Mooley, of the National Radio Astronomy Observatory (NRAO) and Caltech.

The technique is similar to that using the supernova explosions. Type Ia supernova explosions are thought to all have an intrinsic brightness which can be calculated based on the speed at which they brighten and then fade away. Measuring the brightness as seen from Earth then tells the distance to the supernova explosion. Measuring the Doppler shift of the light from the supernova’s host galaxy indicates the speed at which the galaxy is receding from Earth. The speed divided by the distance yields the Hubble Constant. To get an accurate figure, many such measurements must be made at different distances.

When two massive neutron stars collide, they produce an explosion and a burst of gravitational waves. The shape of the gravitational-wave signal tells scientists how “bright” that burst of gravitational waves was. Measuring the “brightness,” or intensity of the gravitational waves as received at Earth can yield the distance.

“This is a completely independent means of measurement that we hope can clarify what the true value of the Hubble Constant is,” Mooley said.

However, there’s a twist. The intensity of the gravitational waves varies with their orientation with respect to the orbital plane of the two neutron stars. The gravitational waves are stronger in the direction perpendicular to the orbital plane, and weaker if the orbital plane is edge-on as seen from Earth.

“In order to use the gravitational waves to measure the distance, we needed to know that orientation,” said Adam Deller, of Swinburne University of Technology in Australia.

Over a period of months, the astronomers used the radio telescopes to measure the movement of a superfast jet of material ejected from the explosion. “We used these measurements along with detailed hydrodynamical simulations to determine the orientation angle, thus allowing use of the gravitational waves to determine the distance,” said Ehud Nakar from Tel Aviv University.

This single measurement, of an event some 130 million light-years from Earth, is not yet sufficient to resolve the uncertainty, the scientists said, but the technique now can be applied to future neutron-star mergers detected with gravitational waves.

“We think that 15 more such events that can be observed both with gravitational waves and in great detail with radio telescopes, may be able to solve the problem,” said Kenta Hotokezaka, of Princeton University. “This would be an important advance in our understanding of one of the most important aspects of the Universe,” he added.

The international scientific team led by Hotokezaka is reporting its results in the journal Nature Astronomy.

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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

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (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).

NRAO VLBA

NRAO/VLBA

*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.

And the future Expanded Very Large Array (EVLA).

#new-method-may-resolve-difficulty-in-measuring-universes-expansion, #astronomy, #astrophysics, #basic-research, #cosmology, #nrao, #radio-astronomy

From ALMA via NRAO: “Tale As Old As Time”

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

From ALMA

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National Radio Astronomy Observatory

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January 7, 2019

Hot spots in the cosmic microwave background tell us about the history and evolution of distant quasars.

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Credit: NRAO/AUI/NSF

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Image author of a quasar. Credit: NRAO / AUI / NSF.

Synopsis: Using data from ALMA, a team of astronomers studied the growth and evolution of bubbles of hot plasma produced by active quasar HE 0515-4414. The bubble was analyzed by observing its effect on light from the cosmic microwave background. It is the first time this method has been used to directly study outflows from quasars.

Cosmic microwave background radiation is the first light in the cosmos.

Cosmic microwave background radiation. Stephen Hawking Center for Theoretical Cosmology U Cambridge

The light we see began its journey when the universe was just 380,000 years old, when the temperature of the universe had finally dropped to the point where the primordial plasma of electrons and protons cooled enough to form transparent hydrogen gas. At first, the cosmic background was a nearly perfect blackbody spectrum. A blackbody spectrum is the spectrum of light caused by the temperature of an object. Sunlight, for example, is also a blackbody spectrum. Shortly after it first appeared, the cosmic blackbody was an orange glow, but during its 13.7 billion year journey the expansion of the universe shifted it to infrared and then microwave radiation. We now see this background as a faint glow of microwave light coming from all directions.

CMB per ESA/Planck


ESA/Planck 2009 to 2013

The cosmic background is still a blackbody, but not a perfect one. There are small fluctuations in the background. Regions that are a bit warmer than average, and regions that are slightly cooler. Most of these fluctuations are due to variations in the early universe. Slightly warmer regions expanded to fill the vast voids between galaxies, while slightly cooler regions condensed into galaxies and clusters of galaxies.

But some of these fluctuations are due to the tremendously long journey the light took to reach us. While traveling for billions of years, the light of the cosmic background passed through all the gas, dust and plasma between us and its source. Some of the light was absorbed. Some lost energy by scattering and now appears cooler than it would otherwise. But some of it gained energy, making the cosmic background appear warmer than it should.

This warming process is known as the Sunyaev–Zel’dovich effect (or SZ effect). When low energy photons from the cosmic microwave background pass through a region of hot plasma, they can collide with fast-moving electrons. The photons are then scattered with a great deal of energy. So the cosmic light leaves the region warmer and brighter – leaving a “hole” in the background at low frequencies, corresponding to lower photon energies. By looking for temperature fluctuations in the cosmic background, astronomers can study regions of hot plasma.

In a recent paper published in the Monthly Notices of the Royal Astronomical Society, a team of researchers used the SZ effect to study bubbles of hot plasma near distant quasars. Quasars are bright radio beacons in the sky. They are powered by supermassive black holes in the hearts of galaxies. As the black holes consume matter near them, they radiate tremendous energy. They are often more than 100 times brighter than the galaxy in which they live. This can create a quasar wind of ionized gas that streams away from the galaxy, similar to the way our Sun creates a solar wind. When the quasar wind collides with the diffuse and cool gas of intergalactic space, it can create bubbles of hot plasma.

Quasars aren’t as distant as the cosmic microwave background, but they are still billions of light-years away. That means any light given off by the plasma bubbles is much too faint to be observed directly. But they can be studied through the SZ effect. In order to do that, however, you need to capture high-resolution images of the microwave background. This is where the Atacama Large Millimeter/submillimeter Array (ALMA) comes in. Located high in the Andes of northern Chile, ALMA can capture microwave images at a resolution similar to visible light images captured by the Hubble space telescope. Just as the Hubble can show us beautiful images of distant nebulae, ALMA can capture images of hot plasma bubbles.

Using data from ALMA, the astronomers detected a bubble near the quasar HE 0515-4414. This is a hyperluminous quasar, meaning that it is extremely bright and active. But surprisingly when they used their data to measure the quasar wind, they found it was smaller than anticipated. The quasar wind is only 0.01% of the total luminosity of the quasar. Theoretical models predicted that the quasar wind should be much stronger. It seems that while quasars can create hot bubbles of plasma around a galaxy, the process isn’t particularly efficient.

The scale of the bubble also told them it formed over a period of about 100 million years, and it will take about 600 million years to cool down. Those time scales are long enough that hot plasma bubbles could interact with cooler material in the galaxy to influence star production and the evolution of the galaxy.

Of course this is just the first hot plasma bubble to be observed, and it’s impossible to know if HE 0515-4414 is typical or a rare exception. So the search is on to find more bubble-blowing quasars.

See the full article here .

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Please help promote STEM in your local schools.

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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.

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#alma, #astronomy, #astrophysics, #basic-research, #cosmology, #nrao, #quasars

From National Radio Astronomy Observatory: CASA News

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From National Radio Astronomy Observatory

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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

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (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).

NRAO VLBA

NRAO VLBA

*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.

And the future Expanded Very Large Array (EVLA).

#astronomy, #astrophysics, #basic-research, #casa-news, #cosmology, #nrao, #radio-astronomy

From National Radio Astronomy Observatory via Manu Garcia of IAC: “VLA Sky Survey Reveals First “Orphan” Gamma Ray Burst”


From Manu Garcia, a friend from IAC.

The universe around us.
Astronomy, everything you wanted to know about our local universe and never dared to ask.

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From National Radio Astronomy Observatory

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October 4, 2018
Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu

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Credit: Bill Saxton, NRAO/AUI/NSF

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Series of radio images of FIRST J1419+3940 from 1993 to 2017 show its slow fade. Credit: Law et al., Bill Saxton, NRAO/AUI/NSF

Astronomers comparing data from an ongoing major survey of the sky using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to data from earlier surveys likely have made the first discovery of the afterglow of a powerful gamma ray burst that produced no gamma rays detectable at Earth. The unprecedented discovery of this “orphan” gamma ray burst (GRB) offers key clues to understanding the aftermath of these highly energetic events.

NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

“GRBs emit their gamma rays in narrowly focused beams. In this case, we believe the beams were pointed away from Earth, so gamma ray telescopes did not see this event. What we found is the radio emission from the explosion’s aftermath, acting over time much as we expect for a GRB,” said Casey Law, of the University of California, Berkeley.

While searching through data from the first epoch of observing for the VLA Sky Survey (VLASS) in late 2017, the astronomers noted that an object that appeared in images from an earlier VLA survey in 1994 did not appear in the VLASS images. They then searched for additional data from the VLA and other radio telescopes. They found that observations of the object’s location in the sky dating back as far as 1975 had not detected it until it first appeared in a VLA image from 1993.

The object then appeared in several images made with the VLA and the Westerbork telescope in the Netherlands from 1993 through 2015. The object, dubbed FIRST J1419+3940, is in the outskirts of a galaxy more than 280 million light-years from Earth.

“This is a small galaxy with active star formation, similar to others in which we have seen the type of GRBs that result when a very massive star explodes,” Law said.

The strength of the radio emission from J1419+3940 and the fact that it slowly evolved over time support the idea that it is the afterglow of such a GRB, the scientists said. They suggested that the explosion and burst of gamma rays should have been seen sometime in 1992 or 1993.

However, after searching databases from gamma ray observatories, “We could find no convincing candidate for a detected GRB from this galaxy,” Law said.

While there are other possible explanations for the object’s behavior, the scientists said that a GRB is the most likely.

“This is exciting, and not just because it probably is the first ‘orphan’ GRB to be discovered. It also is the oldest well-localized GRB, and the long time period during which it has been observed means it can give us valuable new information about GRB afterglows,” Law said.

“Until now, we’ve never seen how the afterglows of GRBs behave at such late times,” noted Brian Metzger of Columbia University, co-author of the study. “If a neutron star is responsible for powering the GRB and is still active, this might give us an unprecedented opportunity to view this activity as the expanding ejecta from the supernova explosion finally becomes transparent.”

“I’m delighted to see this discovery, which I expect will be the first of many to come from the unique investment the National Radio Astronomy Observatory (NRAO) and the National Science Foundation are making in VLASS,” said NRAO Director Tony Beasley.

VLASS is the largest observing project in the history of the VLA. Begun in 2017, the survey will use 5,500 hours of observing time over seven years. The survey will make three complete scans of the sky visible from the VLA, roughly 80 percent of the sky. Initial images from the first round of observations now are available to astronomers.

VLASS follows two earlier sky surveys done with the VLA. The NRAO VLA Sky Survey (NVSS), like VLASS, was an all-sky survey done from 1993 to 1996, and the FIRST (Faint Images of the Radio Sky at Twenty centimeters) survey studied a smaller portion of the sky in more detail from 1993 to 2002. The astronomers discovered FIRST J1419+3940 by comparing a 1994 image from the FIRST survey to the VLASS 2017 data.

From 2001 to 2012, the VLA underwent a major upgrade, greatly increasing its sensitivity, or ability to image faint objects. The upgrade made possible a new, improved survey offering a rich scientific payoff. The earlier surveys have been cited more than 4,500 times in scientific papers, and scientists expect VLASS to be a valuable resource for research in the coming years.

Law and his colleagues are publishing their findings in the Astrophysical Journal Letters.

See the full article here .


five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

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

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (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).

NRAO VLBA

NRAO VLBA

*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.

And the future Expanded Very Large Array (EVLA).

#astronomy, #astrophysics, #basic-research, #cosmology, #nrao, #radio-astronomy, #vla-sky-survey-reveals-first-orphan-gamma-ray-burst

From NRAO via newswise: “VLA Gives Tantalizing Clues About Source of Energetic Cosmic Neutrino”

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Supermassive black hole at core of galaxy accelerates particles in jets moving outward at nearly the speed of light. In a Blazar, one of these jets is pointed nearly straight at Earth. Credit: Sophia Dagnello, NRAO/AUI/NSF

A single, ghostly subatomic particle that traveled some 4 billion light-years before reaching Earth has helped astronomers pinpoint a likely source of high-energy cosmic rays for the first time. Subsequent observations with the National Science Foundation’s (NSF) Karl G. Jansky Very Large Array (VLA) [depicted below] have given the scientists some tantalizing clues about how such energetic cosmic rays may be formed at the cores of distant galaxies.

On September 22, 2017, an observatory called IceCube, made up of sensors distributed through a square kilometer of ice under the South Pole, recorded the effects of a high-energy neutrino coming from far beyond our Milky Way Galaxy.

U Wisconsin ICECUBE neutrino detector at the South Pole

Lunar Icecube

IceCube DeepCore annotated

IceCube PINGU annotated


DM-Ice II at IceCube annotated

Neutrinos are subatomic particles with no electrical charge and very little mass. Since they interact only very rarely with ordinary matter, neutrinos can travel unimpeded for great distances through space.

Follow-up observations with orbiting and ground-based telescopes from around the world soon showed that the neutrino likely was coming from the location of a known cosmic object — a blazar called TXS 0506+056, about 4 billion light-years from Earth.

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Like most galaxies, blazars contain supermassive black holes at their cores. The powerful gravity of the black hole draws in material that forms a hot rotating disk. Jets of particles traveling at nearly the speed of light are ejected perpendicular to the disk. Blazars are a special class of galaxies, because in a blazar, one of the jets is pointed almost directly at Earth.

Theorists had suggested that these powerful jets could greatly accelerate protons, electrons, or atomic nuclei, turning them into the most energetic particles known in the Universe, called ultra-high energy cosmic rays. The cosmic rays then could interact with material near the jet and produce high-energy photons and neutrinos, such as the neutrino detected by IceCube.

Cosmic rays were discovered in 1912 by physicist Victor Hess, who carried instruments in a balloon flight. Subsequent research showed that cosmic rays are either protons, electrons, or atomic nuclei that have been accelerated to speeds approaching that of light, giving some of them energies much greater than those of even the most energetic electromagnetic waves. In addition to the active cores of galaxies, supernova explosions are probable sites where cosmic rays are formed. The galactic black-hole engines, however, have been the prime candidate for the source of the highest-energy cosmic rays, and thus of the high-energy neutrinos resulting from their interactions with other matter.

“Tracking that high-energy neutrino detected by IceCube back to TXS 0506+056 makes this the first time we’ve been able to identify a specific object as the probable source of such a high-energy neutrino,” said Gregory Sivakoff, of the University of Alberta in Canada.

Following the IceCube detection, astronomers looked at TXS 0506+056 with numerous telescopes and found that it had brightened at wavelengths including gamma rays, X-rays, and visible light. The blazar was observed with the VLA six times between October 5 and November 21, 2017.

“The VLA data show that the radio emission from this blazar was varying greatly at the time of the neutrino detection and for two months afterward. The radio frequency with the brightest radio emission also was changing,” Sivakoff said.

TXS 0506+056 has been monitored over a number of years with the NSF’s Very Long Baseline Array (VLBA), a continent-wide radio telescope system that produces extremely detailed images. The high-resolution VLBA images have shown bright knots of radio emission that travel outward within the jets at speeds nearly that of light. The knots presumably are caused by denser material ejected sporadically through the jet.

“The behavior we saw with the VLA is consistent with the emission of at least one of these knots. It’s an intriguing possibility that such knots may be associated with generating high-energy cosmic rays and thus the kind of high-energy neutrino that IceCube found,” Sivakoff said.

The scientists continue to study TXS 0506+056. “There are a lot of exciting phenomena going on in this object,” Sivakoff concluded.

“The era of multi-messenger astrophysics is here,” said NSF Director France Córdova. “Each messenger — from electromagnetic radiation, gravitational waves and now neutrinos — gives us a more complete understanding of the Universe, and important new insights into the most powerful objects and events in the sky. Such breakthroughs are only possible through a long-term commitment to fundamental research and investment in superb research facilities.”

Sivakoff and numerous colleagues from institutions around the world are reporting their findings in the journal Science.

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

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (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).

NRAO VLBA

NRAO VLBA

*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.

And the future Expanded Very Large Array (EVLA).

#blazar, #blazars, #karl-v-jansky-nrao-vla, #multi-messenger-astrophysics, #neutrinos, #newswise, #nrao, #txs-0506056, #u-wisconsin-icecube-and-icecube-gen-2