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  • richardmitnick 10:11 am on April 8, 2019 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA, , VLA Makes First Direct Image of Key Feature of Powerful Radio Galaxies   

    From National Radio Astronomy Observatory: “VLA Makes First Direct Image of Key Feature of Powerful Radio Galaxies” 

    From National Radio Astronomy Observatory

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    April 2, 2019

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

    1
    Artist’s conception of the dusty, doughnut-shaped object surrounding the supermassive black hole, disk of material orbiting the black hole, and jets of material ejected by the disk, at the center of a galaxy. Credit: Bill Saxton, NRAO/AUI/NSF

    2
    Artist’s conception of active galactic nucleus, with labels. Credit: Bill Saxton, NRAO/AUI/NSF

    3
    VLA image of the central region of the powerful radio galaxy Cygnus A, showing the doughnut-shaped torus surrounding the black hole and accretion disk. Credit: Carilli et al., NRAO/AUI/NSF

    4

    VLA image of Cygnus A’s central region, with labels.
    Credit: Carilli et al., NRAO/AUI/NSF

    Astronomers used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to make the first direct image of a dusty, doughnut-shaped feature surrounding the supermassive black hole at the core of one of the most powerful radio galaxies in the Universe — a feature first postulated by theorists nearly four decades ago as an essential part of such objects.

    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)

    The scientists studied Cygnus A, a galaxy some 760 million light-years from Earth. The galaxy harbors a black hole at its core that is 2.5 billion times more massive than the Sun. As the black hole’s powerful gravitational pull draws in surrounding material, it also propels superfast jets of material traveling outward at nearly the speed of light, producing spectacular “lobes” of bright radio emission.

    Black hole-powered “central engines” producing bright emission at various wavelengths, and jets extending far beyond the galaxy are common to many galaxies, but show different properties when observed. Those differences led to a variety of names, such as quasars, blazars, or Seyfert galaxies. To explain the differences, theorists constructed a “unified model” with a common set of features that would show different properties depending on the angle from which they are viewed.

    The unified model includes the central black hole, a rotating disk of infalling material surrounding the black hole, and the jets speeding outward from the poles of the disk. In addition, to explain why the same type of object looks different when viewed from different angles, a thick, dusty, doughnut-shaped “torus” is included, surrounding the inner parts. The torus obscures some features when viewed from the side, leading to apparent differences to the observer, even for intrinsically similar objects. Astronomers generically call this common set of features an active galactic nucleus (AGN).

    “The torus is an essential part of the AGN phenomenon, and evidence exists for such structures in nearby AGN of lower luminosity, but we’ve never before directly seen one in such a brightly-emitting radio galaxy,” said Chris Carilli, of the National Radio Astronomy Observatory (NRAO). “The torus helps explain why objects known by different names actually are the same thing, just observed from a different perspective,” he added.

    In the 1950s, astronomers discovered objects that strongly emitted radio waves, but appeared point-like, similar to distant stars, when later observed with visible-light telescopes. In 1963, Maarten Schmidt of Caltech discovered that one of these objects was extremely distant, and more such discoveries quickly followed. To explain how these objects, dubbed quasars, could be so bright, theorists suggested that they must be tapping the tremendous gravitational energy of supermassive black holes. The combination of black hole, the rotating disk, called an accretion disk, and the jets was termed the “central engine” responsible for the objects’ prolific outpourings of energy.

    The same type of central engine also appeared to explain the output of other types of objects, including radio galaxies, blazars, and Seyfert Galaxies. However, each showed a different set of properties. Theorists worked to develop a “unification scheme” to explain how the same thing could appear differently. In 1977, obscuration by dust was suggested as one element of that scheme. In a 1982 paper, Robert Antonucci, of the University of California, Santa Barbara, presented a drawing of an opaque torus — a doughnut-shaped object — surrounding the central engine. From that point on, an obscuring torus has been a common feature of astronomers’ unified view of all types of active galactic nuclei.

    “Cygnus A is the closest example of a powerful radio-emitting galaxy — 10 times closer than any other with comparably powerful radio emission. That proximity allowed us to find the torus in a high-resolution VLA image of the galaxy’s core,” said Rick Perley, also of NRAO. “Doing more work of this type on weaker and more distant objects will almost certainly need the order-of-magnitude improvement in sensitivity and resolution that the proposed Next Generation Very Large Array (ngVLA) would bring,” he added.

    The VLA observations directly revealed the gas in Cygnus A’s torus, which has a radius of nearly 900 light-years. Longstanding models for the torus suggest that the dust is in clouds embedded in the somewhat-clumpy gas.

    “It’s really great to finally see direct evidence of something that we’ve long presumed should be there,” Carilli said. “To more accurately determine the shape and composition of this torus, we need to do further observing. For example, the Atacama Large Millimeter/submillimeter Array (ALMA) can observe at the wavelengths that will directly reveal the dust,” he added.

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

    Carilli and Perley, with their colleagues Vivek Dhawan, also of NRAO, and Daniel Perley of Liverpool John Moores University in the UK, discovered the torus when following up their surprising discovery in 2016 of a new, bright object near the center of Cygnus A. That new object, they said, is most likely a second supermassive black hole that only recently encountered new material it could devour, causing it to produce bright emission the same way the central black hole does. The existence of the second black hole, they said, suggests that Cygnus A merged with another galaxy in the astronomically recent past.

    Cygnus A, so named because it is the most powerful radio-emitting object in the constellation Cygnus, was discovered in 1946 by English physicist and radio astronomer J.S. Hey. It was matched to a visible-light, giant galaxy by Walter Baade and Rudolf Minkowski in 1951. It became an early target for the VLA soon after its completion in the early 1980s. Detailed VLA images of Cygnus A published in 1984 produced major advances in astronomers’ understanding of such galaxies.

    The scientists are reporting their findings in the Astrophysical Journal Letters.

    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).

     
  • richardmitnick 9:52 pm on February 15, 2019 Permalink | Reply
    Tags: "Space Cow Mystifies Astronomers", , , , , Could we be witnessing a dying star giving birth to an X-ray engine?, , , Karl V Jansky NRAO VLA   

    From ESOblog: “Space Cow Mystifies Astronomers” 

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    From ESOblog

    1
    Science Snapshots – ALMA

    Could we be witnessing a dying star giving birth to an X-ray engine?

    15 February 2019

    One night in June 2018, telescopes spotted an extremely bright point of light in the sky that had seemingly appeared out of nowhere. Observations across the electromagnetic spectrum, made using telescopes from around the world, suggest that the light is likely to be the explosive death of a star giving birth to a neutron star or black hole. If so, this would be the first time ever that this has been observed. We find out more from Anna Ho, who led a team that used a variety of telescopes to figure out what exactly this mysterious object — classified as a transient and nicknamed The Cow — is.

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    Anna Ho

    Q. What is a transient, and why it is interesting to study them?

    A. The night sky appears calm but it is actually incredibly dynamic, with stars exploding in distant galaxies, visible through our telescopes as flashes of light. The word “transient” refers to a short-lived phenomenon in the night sky, which could be the explosion of a dying star, a tidal disruption event, or a flare from a star in the Milky Way. And there are probably many other types of transients out there that we have not even discovered!

    Q. So given that transients are sudden phenomena that you can’t predict, how can you possibly plan for studying them?

    A. It’s kind of a case of reacting to their appearance. In the past few years, we’ve entered this amazing new era of astronomy where telescopes can map out the entire sky every night. By comparing tonight’s map to last night’s map, we can see exactly what has changed over the previous 24 hours. The transients I study are very short-lived explosions — lasting between a few hours and a few months — so when an interesting one happens, we have to drop everything and react. Luckily I love my research enough to do this!

    It is only by using lots of different telescopes that we can really get a full picture of a transient.

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    ALMA and Very Large Array (VLA) images of the mysterious transient, The Cow.
    Credit: Sophia Dagnello, NRAO/AUI/NSF; R. Margutti, W.M. Keck Observatory; Ho, et al.

    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)

    Q. In June 2018, you observed an unusual transient that was named AT2018cow, or The Cow. Can you describe this phenomenon? What made it so remarkable?

    A. One night, astronomers saw a point of light in the sky that had not been there before: a new transient! The Cow was particularly special for two reasons: firstly, it was VERY bright, and secondly, it had achieved that brightness VERY quickly. This was exciting, because usually if a transient appears very quickly, it is not so bright, and a very bright transient takes a long time to become bright. So we realised immediately that this was something strange.

    Q. You chose to study this transient with two millimetre telescopes: the Submillimeter Array (SMA) and ALMA (Atacama Large Millimeter/Submillimeter Array). What do millimetre telescopes offer over other telescopes?

    CfA Submillimeter Array Mauna Kea, Hawaii, USA, Altitude 4,080 m (13,390 ft)

    A. In the early stages of a transient (in its first few weeks of existence), we can see the shockwave emitted by an explosion by capturing light at millimetre wavelengths — this is exactly what SMA and ALMA can see. In particular, thanks to ALMA we were able to learn that in the case of The Cow, the shockwave was travelling at one-tenth of the speed of light, that it is very energetic, and that it is travelling into a very dense environment.

    We also used the Australia Telescope Compact Array to look at light from the transient with longer wavelengths. It is only by using lots of different telescopes that we can really get a full picture of a transient.

    CSIRO Australia Compact Array, six radio telescopes at the Paul Wild Observatory, is an array of six 22-m antennas located about twenty five kilometres (16 mi) west of the town of Narrabri in Australia.

    By combining ALMA data with publicly available X-ray data, we were also able to conclude that there must be some ongoing energy production — a kind of continuously-running “engine” at the heart of the explosion. This could be an accreting black hole or a rapidly-spinning neutron star with a strong magnetic field (a magnetar). If The Cow does turn out to have either of these at its centre, it would be very exciting, since it would be the first time that astronomers have witnessed the birth of a central engine.

    Q. It seems that nobody’s quite sure what The Cow is. Why is there so much uncertainty still surrounding this object?

    A. It’s because the combination of The Cow’s properties is so unusual. It’s like that parable of the blind man and the elephant — where several blind men each feel a different part of an elephant and come to different conclusions about what it might look like. If you look at the visible light from The Cow, you might conclude that it is a tidal disruption event. On the other hand, if you look at the longer-wavelength light you see the properties of the shockwave and the density of the surrounding matter, and might conclude that it’s a stellar explosion. It’s incredibly difficult to reconcile all of the properties into one big picture.

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    Artist’s impression of a cosmic blast with a “central engine,” such as that suggested for The Cow. At the moment, the central engine is surrounded by dust and gas.
    Credit: Bill Saxton, NRAO/AUI/NSF

    Q. How will you find out what The Cow really is?

    A. Right now, the heart of the explosion is shrouded in gas and dust so it’s difficult to see it. Over the next months, this gas and dust will expand out into space, becoming thinner and more transparent, and allowing us to peer inside. When we are able to see into that central engine, we will be able to learn more about what it there, whether it’s a black hole, a neutron star, or something else entirely.

    Q. What do you think The Cow is, and why?

    A. Personally, I think it’s most likely to be a stellar explosion. Our ALMA observations enabled us to measure the surrounding environment to be incredibly dense — 300 000 particles per cubic centimetre! This kind of density is typical of a stellar explosion. Some people suggest it’s a tidal disruption event, but I think this would be difficult to explain. That said, I’m far from an expert on tidal disruption, so I look forward to hearing more from theorists on how to reconcile that model with our observations.

    Q. So what are the implications of this discovery? What does The Cow teach us about transients?

    A. From my perspective, The Cow is incredibly exciting for two reasons. One is astrophysical — what it can teach us about the death of stars. We think we’ve witnessed the birth of a central engine, an accreting black hole or a spinning neutron star, for the first time.

    The second reason is technological — we learned that this is a member of a whole class of explosions that in their youth emitted bright light at millimetre wavelengths. In the past, millimetre observatories like ALMA were rarely used to study cosmic explosions, but this study has opened the curtain on a new class of transients that are prime targets for millimetre observatories. Over the next few years, we hope to discover many more members of this class, and now we know that we should use millimetre telescopes to study them!

    See the full article here .


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  • richardmitnick 12:24 pm on August 4, 2018 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA,   

    From National Radio Astronomy Observatory via Manu: “VLA Detects Possible Extrasolar Planetary-Mass Magnetic Powerhouse” 


    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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    August 2, 2018

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

    Object is at boundary between giant planet and brown dwarf.

    1
    Artist’s conception of SIMP J01365663+0933473, an object with 12.7 times the mass of Jupiter, but a magnetic field 200 times more powerful than Jupiter’s. This object is 20 light-years from Earth. Credit: Caltech/Chuck Carter; NRAO/AUI/NSF

    Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have made the first radio-telescope detection of a planetary-mass object beyond our Solar System. The object, about a dozen times more massive than Jupiter, is a surprisingly strong magnetic powerhouse and a “rogue,” traveling through space unaccompanied by any parent star.

    “This object is right at the boundary between a planet and a brown dwarf, or ‘failed star,’ and is giving us some surprises that can potentially help us understand magnetic processes on both stars and planets,” said Melodie Kao, who led this study while a graduate student at Caltech, and is now a Hubble Postdoctoral Fellow at Arizona State University.

    Brown dwarfs are objects too massive to be considered planets, yet not massive enough to sustain nuclear fusion of hydrogen in their cores — the process that powers stars. Theorists suggested in the 1960s that such objects would exist, but the first one was not discovered until 1995. They originally were thought to not emit radio waves, but in 2001 a VLA discovery of radio flaring in one revealed strong magnetic activity.

    Subsequent observations showed that some brown dwarfs have strong auroras, similar to those seen in our own Solar System’s giant planets. The auroras seen on Earth are caused by our planet’s magnetic field interacting with the solar wind. However, solitary brown dwarfs do not have a solar wind from a nearby star to interact with. How the auroras are caused in brown dwarfs is unclear, but the scientists think one possibility is an orbiting planet or moon interacting with the brown dwarf’s magnetic field, such as what happens between Jupiter and its moon Io.

    The strange object in the latest study, called SIMP J01365663+0933473, has a magnetic field more than 200 times stronger than Jupiter’s. The object was originally detected in 2016 as one of five brown dwarfs the scientists studied with the VLA to gain new knowledge about magnetic fields and the mechanisms by which some of the coolest such objects can produce strong radio emission. Brown dwarf masses are notoriously difficult to measure, and at the time, the object was thought to be an old and much more massive brown dwarf.

    Last year, an independent team of scientists discovered that SIMP J01365663+0933473 was part of a very young group of stars. Its young age meant that it was in fact so much less massive that it could be a free-floating planet — only 12.7 times more massive than Jupiter, with a radius 1.22 times that of Jupiter. At 200 million years old and 20 light-years from Earth, the object has a surface temperature of about 825 degrees Celsius, or more than 1500 degrees Fahrenheit. By comparison, the Sun’s surface temperature is about 5,500 degrees Celsius.

    The difference between a gas giant planet and a brown dwarf remains hotly debated among astronomers, but one rule of thumb that astronomers use is the mass below which deuterium fusion ceases, known as the “deuterium-burning limit”, around 13 Jupiter masses.

    Simultaneously, the Caltech team that originally detected its radio emission in 2016 had observed it again in a new study at even higher radio frequencies and confirmed that its magnetic field was even stronger than first measured.

    “When it was announced that SIMP J01365663+0933473 had a mass near the deuterium-burning limit, I had just finished analyzing its newest VLA data,” said Kao.

    The VLA observations provided both the first radio detection and the first measurement of the magnetic field of a possible planetary mass object beyond our Solar System.

    Such a strong magnetic field “presents huge challenges to our understanding of the dynamo mechanism that produces the magnetic fields in brown dwarfs and exoplanets and helps drive the auroras we see,” said Gregg Hallinan, of Caltech.

    “This particular object is exciting because studying its magnetic dynamo mechanisms can give us new insights on how the same type of mechanisms can operate in extrasolar planets — planets beyond our Solar System. We think these mechanisms can work not only in brown dwarfs, but also in both gas giant and terrestrial planets,” Kao said.

    “Detecting SIMP J01365663+0933473 with the VLA through its auroral radio emission also means that we may have a new way of detecting exoplanets, including the elusive rogue ones not orbiting a parent star,” Hallinan said.

    Kao and Hallinan worked with J. Sebastian Pineda who also was a graduate student at Caltech and is now at the University of Colorado Boulder, David Stevenson of Caltech, and Adam Burgasser of the University of California San Diego. They are reporting their findings in The Astrophysical Journal.

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

    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).

     
  • richardmitnick 3:07 pm on July 12, 2018 Permalink | Reply
    Tags: Blazar, , Karl V Jansky NRAO VLA, , , , , ,   

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

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    newswise

    1
    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.

    3

    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).

     
  • richardmitnick 6:57 am on March 16, 2018 Permalink | Reply
    Tags: $23 Million in New Funding for Dunlap Institute Astronomers, , , , , , , , Karl V Jansky NRAO VLA,   

    From Dunlap: “$23 Million in New Funding for Dunlap Institute Astronomers” 

    Dunlap Institute bloc
    Dunlap Institute for Astronomy and Astrophysics

    Oct 12,2017

    Prof. Bryan Gaensler, Director
    Dunlap Institute for Astronomy & Astrophysics
    University of Toronto
    p: 416-978-6623
    e: bgaensler@dunlap.utoronto.ca
    web: http://www.dunlap.utoronto.ca/prof-bryan-gaensler/

    Prof. Suresh Sivanandam
    Dunlap Institute for Astronomy & Astrophysics
    University of Toronto
    p: 416-978-6779
    e: sivanandam@dunlap.utoronto.ca
    web: http://www.dunlap.utoronto.ca/suresh-sivanandam/

    Chris Sasaki
    Communications Coordinator | Press Officer
    Dunlap Institute for Astronomy & Astrophysics
    University of Toronto
    p: 416-978-6613
    e: csasaki@dunlap.utoronto.ca

    Astronomers from the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics have received $23 million in new funding: $10 million for the development of a radio astronomy data centre and $13 million for a new infrared spectrograph.

    The awards represent a significant milestone in the Dunlap’s mandate of developing innovative astronomical technology.

    “The Dunlap Institute’s main mission is to develop innovative new approaches to astronomy, and these two new large grants are a terrific endorsement that we’re on the right track,” says Dunlap Director Prof. Bryan Gaensler.

    “In particular, these projects superbly position the Dunlap Institute for national and international leadership. We’re excited to now flex our muscles and build big, new teams that will develop the tools and equipment needed for 21st century astronomy.”

    Gaensler, who became the Institute’s director in January 2015, will be leading a project to build the infrastructure, computing capability, and expertise needed to process the overwhelming flood of information being produced by next-generation radio telescopes. The goal is to turn raw data into images and catalogues that astronomers can use to investigate cosmic magnetism, the evolution of galaxies, cosmic explosions, and more.

    The Dunlap’s Prof. Suresh Sivanandam will develop an infrared spectrograph for the Gemini Observatory that will produce the most detailed and sensitive infrared images of the sky. With it, astronomers will be able to study some of the faintest, oldest and most distant objects in the Universe; probe the formation of stellar and planetary systems; and investigate galaxies in the early Universe.

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

    Gaensler’s project will allow Canada to play a major role in the Very Large Array Sky Survey (VLASS), an ambitious new project to make a radio map of almost the entire sky in unprecedented detail. It will also help build the Canadian capacity needed to participate in what will be the largest and most powerful radio telescope ever constructed: the Square Kilometre Array.

    SKA Square Kilometer Array

    Major partners include observatories and researchers at various universities across North America, including the US National Radio Astronomy Observatory, University of Alberta, University of Manitoba, and the National Research Council. It also includes collaborators from three significant new radio telescopes: the Canadian Hydrogen Intensity Mapping Experiment (CHIME), the Karl G. Jansky Very Large Array (VLA), and the Australian Square Kilometre Array Pathfinder (ASKAP).

    CHIME Canadian Hydrogen Intensity Mapping Experiment A partnership between the University of British Columbia McGill University, at the Dominion Radio Astrophysical Observatory in British Columbia

    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia

    The Gemini InfraRed Multi-Object Spectrograph (GIRMOS) is unlike any astronomical spectrograph in existence or being planned for the current suite of large telescopes, and will serve as a precursor to a spectrograph for the Thirty-Meter Telescope, now under construction in Hawaií.

    Gemini InfraRed Multi-Object Spectrograph (GIRMOS) for TMT

    TMT-Thirty Meter Telescope, proposed and now approved for Mauna Kea, Hawaii, USA4,207 m (13,802 ft) above sea level

    The spectrograph is designed for use on the 8-metre telescopes of the Gemini Observatory, the largest telescopes available to Canadian astronomers.


    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet


    Gemini/North telescope at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

    Major partners include Dalhousie University, the National Research Council, University of British Columbia, University of Victoria, Laval University, and Saint Mary’s University.

    Plus, both projects provide ample opportunities for training students and postdoctoral fellows, and help position Canadian astronomers at the forefront of the next generation of astronomical discovery.

    The annual CFI Innovation Fund awards support transformative and innovative research or technology development in areas where Canada currently is, or has the potential to be, competitive at a global level.

    For Gaensler, the awards consist of $3.5 million from CFI, and nearly $6 million from provincial and other partners. The CFI money will flow to U of T and then on to the other partners; the rest will go directly to or stay with partners. For Sivanandam, over $5 million comes from CFI, with $7.8 million from provincial and other partners.

    The awards were announced today by the Honourable Kirsty Duncan, Minister of Science, in a ceremony at the University of Manitoba, as part of a CFI investment of more than $554 million in 117 new infrastructure projects at 61 universities, colleges and research hospitals across Canada.

    Additional notes:

    1) In addition to those noted above, Prof. Gaensler’s project also includes the following partners: McGill University, Queen’s University, University of British Columbia, Cornell University, University of Minnesota, Netherlands Institute for Radio Astronomy, University of Cape Town, University of the Western Cape, and University of California Berkeley.

    2) In addition to those partners noted above, Prof. Sivanandam’s project also includes York University and University of Manitoba.

    3) The following statement has been added to the original release: “The CFI money will flow to U of T and then on to the other partners; the rest will go directly to or stay with partners.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Dunlap Institute campus

    The Dunlap Institute is committed to sharing astronomical discovery with the public. Through lectures, the web, social and new media, an interactive planetarium, and major events like the Toronto Science Festival, we are helping to answer the public’s questions about the Universe.
    Our work is greatly enhanced through collaborations with the Department of Astronomy & Astrophysics, Canadian Institute for Theoretical Astrophysics, David Dunlap Observatory, Ontario Science Centre, Royal Astronomical Society of Canada, the Toronto Public Library, and many other partners.

     
  • richardmitnick 2:35 pm on December 31, 2017 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA, , ,   

    From NRAO: “Next-generation U.S. Radio Telescope Development Begins” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    September 14, 2017
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    Planning begins for next leap forward in research capability.

    1
    Artist’s conception of the multi-antenna Next generation VLA (ngVLA). Credit: Bill Saxton, NRAO/AUI/NSF

    The National Radio Astronomy Observatory (NRAO) and Associated Universities, Inc. (AUI) are launching a new initiative to design a next-generation radio telescope with scientific capabilities far beyond those provided by any existing or currently proposed observatory.

    Building on the success of one of the National Science Foundation’s (NSF) flagship observatories, the Karl G. Jansky Very Large Array (VLA), NRAO and AUI are beginning a two-year project to explore the science opportunities, design concepts, and technologies needed to construct a new class of radio telescope.

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

    This proposed array, consisting of more than 200 antennas, would extend across the desert southwest of the United States and into northern Mexico.

    Currently dubbed the next-generation Very Large Array, or ngVLA for short, the new research facility will be designed to provide the next leap forward in our understanding of planets, galaxies, black holes, and fundamental physics.

    “The capabilities of the ngVLA are the only means of answering a broad range of critical scientific questions in modern astronomy,” said NRAO Director Tony Beasley. “The ngVLA will open a new window on the Universe, and its scientific and technological innovations promise great contributions to society across many dimensions, including economic development, education, and others,” he added.

    Funding for the new initiative was provided by the National Science Foundation’s Division of Astronomical Sciences, allowing NRAO to re-profile $11M in funding planned for instrument development over a longer time period into a focused two-year effort. This large telescope initiative was included in AUI’s successful proposal to the NSF to manage NRAO over the decade just starting, and NSF’s decision allows NRAO to accelerate the early design studies. This will enable the ngVLA concept to be more fully developed for the next U.S. astronomy Decadal Survey, commencing in 2019-2020, where all major new instruments and capabilities are considered by the research community. A key use of the funding will be exploration of the high-performance antennas that will collect the astronomical signals for analysis.

    “We’re very eager to get this effort underway,” said ngVLA Project Scientist Eric Murphy. “Along with partners and advisors from throughout the astronomical community, we look forward to the challenge of meeting the research needs of the coming decades,” he added.

    “Associated Universities, Inc., recognizes ngVLA as the future of radio astronomy in North America, and we are excited to start developing this new concept,” said AUI President Ethan Schreier. “New Mexico is home to many great astronomical facilities, and ngVLA will continue this proud tradition,“ he said.

    NSF’s Division of Astronomical Sciences is responsible for funding the VLA, the North American share of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and other ground-based astronomical observatories. NSF is an independent federal agency that supports research and education in all non-medical fields of science, and in 2017 provided $75 Million to NRAO to support radio astronomy research in the U.S. and in Chile.

    In New Mexico, planning has begun for the design effort. Last June, NRAO hosted a workshop in Socorro on requirements and concepts for the new telescope. The workshop was attended by astronomers from a variety of specialties and institutions. In the near future, NRAO anticipates working with university and industrial partners as the project advances.

    More information on ngVLA can be found here and here.

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

    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).

     
  • richardmitnick 3:43 pm on December 27, 2017 Permalink | Reply
    Tags: , , , , , , , Karl V Jansky NRAO VLA, , Toothbrush Cluster   

    From CfA: “The Toothbrush Cluster” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    1
    A multiwavelength false-color image of the “Toothbrush” cluster of galaxies, 1RXS J0603.3+4214. The intensity in red shows the radio emission, blue is X -ray, and the background color composite is optical emission. Astronomers studying the cluster with new radio observations combined with other wavelengths have been able to confirm the galaxy merger scenario and estimate the magnetic field strength in the shocks. van Weeren et al.

    Most galaxies lie in clusters containing from a few to thousands of objects. Our Milky Way, for example, belongs to a cluster of about fifty galaxies called the Local Group whose other large member is the Andromeda galaxy about 2.3 million light-years away.

    Local Group. Andrew Z. Colvin 3 March 2011

    Andromeda Galaxy Adam Evans

    Clusters are the most massive gravitationally bound objects in the universe and form (according to current ideas) in a “bottoms-up” fashion with smaller structures developing first and larger groupings assembling later in cosmic history. Dark matter plays an important role in this growth process.

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

    Dark matter halo Image credit: Virgo consortium / A. Amblard / ESA

    Exactly how they grow, however, appears to depend on several competing physical processes including the behavior of the intracluster gas. There is more mass in this gas than there is in all the stars of a cluster’s galaxies, and the gas can have a temperature of ten million kelvin or even higher. As a result, the gas plays an important role in the cluster’s evolution. The hot intracluster gas contains rapidly moving charged particles that radiate strongly at radio wavelengths, sometimes revealing long filamentary structures.

    The “Toothbrush” galaxy cluster, 1RXS J0603.3+4214, hosts three of these radio structures as well as a large halo. The most prominent radio feature extends over more than six million light years, with three distinct components that resemble the brush and handle of a toothbrush. The handle is particularly enigmatic because, besides being large and very straight, it is off center from the axis of the cluster. The halo is thought to result from turbulence produced by the merger of galaxies, although some other possibilities have been suggested.

    CfA astronomers Reinout van Weeren, Bill Forman, Felipe Andrade-Santos, Ralph Kraft, and Christine Jones and their colleagues used the Very Large Array (VLA) facility to observe the relativistic particles in the cluster with precise, sensitive radio imaging, which they compared with Chandra X-ray and other datasets.

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

    NASA/Chandra Telescope

    In the radio, the Toothbrush has a very narrow ridge, created by a huge shock resulting from the merger, and at least thirty-two previously undetected compact sources. The halo’s radio and X-ray morphologies are very similar and lend support to the merger scenario. Astronomers are also able to estimate the strength of the magnetic field, and combined with other results, use it to conclude that the merger scenario is most suitable.

    Reference(s):

    Deep VLA Observations of the Cluster 1RXS J0603.3+4214 in the Frequency Range 1-2 GHz, K. Rajpurohit, M. Hoeft, R. J. van Weeren, L. Rudnick, H. J. A. R ottgering, W. R. Forman, M. Bruggen, J. H. Croston, F. Andrade-Santos, W. A. Dawson, H. T. Intema, R. P. Kraft, C. Jones, and M. James Jee, http://lanl.arxiv.org/abs/1712.01327

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

     
  • richardmitnick 4:49 pm on December 20, 2017 Permalink | Reply
    Tags: A snake-like structure lurking near our galaxy’s supermassive black hole is the latest discovery to tantalize astronomers, , , , , , Karl V Jansky NRAO VLA,   

    From CfA: “Cosmic Filament Probes Our Galaxy’s Giant Black Hole” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    December 20, 2017
    Megan Watzke
    Harvard-Smithsonian Center for Astrophysics
    +1 617-496-7998
    mwatzke@cfa.harvard.edu

    Peter Edmonds
    Harvard-Smithsonian Center for Astrophysics
    +1 617-571-7279
    pedmonds@cfa.harvard.edu

    1
    A radio image from the NSF’s Karl G. Jansky Very Large Array showing the center of our galaxy. The mysterious radio filament is the curved line located near the center of the image, & the supermassive black hole Sagittarius A* (Sgr A*), is shown by the bright source near the bottom of the image. NSF/VLA/UCLA/M. Morris et al.

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

    The center of our Galaxy has been intensely studied for many years, but it still harbors surprises for scientists. A snake-like structure lurking near our galaxy’s supermassive black hole is the latest discovery to tantalize astronomers.

    In 2016, Farhad Yusef-Zadeh of Northwestern University reported the discovery of an unusual filament near the center of the Milky Way Galaxy using the NSF’s Karl G. Jansky Very Large Array (VLA). The filament is about 2.3 light years long and curves around to point at the supermassive black hole, called Sagittarius A* (Sgr A*), located in the Galactic center.

    Now, another team of astronomers has employed a pioneering technique to produce the highest-quality image yet obtained of this curved object.

    “With our improved image, we can now follow this filament much closer to the Galaxy’s central black hole, and it is now close enough to indicate to us that it must originate there,” said Mark Morris of the University of California, Los Angeles, who led the study. “However, we still have more work to do to find out what the true nature of this filament is.”

    The researchers have considered three main explanations for the filament. The first is that it is caused by high-speed particles kicked away from the supermassive black hole. A spinning black hole coupled with gas spiraling inwards can produce a rotating, vertical tower of magnetic field that approaches or even threads the event horizon, the point of no return for infalling matter. Within this tower, particles would be sped up and produce radio emission as they spiral around magnetic field lines and stream away from the black hole.

    The second, more fantastic, possibility is that the filament is a cosmic string, theoretical, as-yet undetected objects that are long, extremely thin objects that carry mass and electric currents. Previously, theorists had predicted that cosmic strings, if they exist, would migrate to the centers of galaxies. If the string moves close enough to the central black hole it might be captured once a portion of the string crosses the event horizon.

    The final option is that the position and the direction of the filament aligning with the black hole are merely coincidental superpositions, and there is no real association between the two. This would imply it is like dozens of other known filaments found farther away from the center of the Galaxy. However, such a coincidence is quite unlikely to happen by chance.

    “Part of the thrill of science is stumbling across a mystery that is not easy to solve,” said co-author Jun-Hui Zhao of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “While we don’t have the answer yet, the path to finding it is fascinating. This result is motivating astronomers to build next generation radio telescopes with cutting edge technology.”

    Each of the scenarios being investigated would provide intriguing insight if proven true. For example, if the filament is caused by particles being ejected by Sgr A*, this would reveal important information about the magnetic field in this special environment, showing that it is smooth and orderly rather than chaotic.

    The second option, the cosmic string, would provide the first evidence for a highly speculative idea with profound implications for understanding gravity, space-time and the Universe itself.

    Evidence for the idea that particles are being magnetically kicked away from the black hole would come from observing that particles further away from Sgr A* are less energetic than those close in. A test for the cosmic string idea will capitalize on the prediction by theorists that the string should move at a high fraction of the speed of light. Follow-up observations with the VLA should be able to detect the corresponding shift in position of the filament.

    Even if the filament is not physically tied to Sgr A*, the bend in the shape of this filament is still unusual. The bend coincides with, and could be caused by, a shock wave, akin to a sonic boom, where the blast wave from an exploded star is colliding with the powerful winds blowing away from massive stars surrounding the central black hole.

    “We will keep hunting until we have a solid explanation for this object,” said co-author Miller Goss, from the National Radio Astronomy Observatory in Socorro, New Mexico. “And we are aiming to next produce even better, more revealing images.”

    A paper describing these results appeared in the December 1st, 2017 issue of The Astrophysical Journal Letters.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

     
  • richardmitnick 9:40 am on November 1, 2017 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA, MACS J1149.5+2233: A Fusion of Galaxy Clusters, , ,   

    From Chandra: “MACS J1149.5+2233: A Fusion of Galaxy Clusters” 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    October 31, 2017

    1
    Composite

    2
    X-ray

    3
    Optical

    4
    Radio

    Credit X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Radio: NSF/NRAO/AUI/VLA

    The Frontier Fields is a project that combines long observations from multiple telescopes of galaxy clusters.

    Galaxy clusters contain up to thousands of galaxies and vast reservoirs of hot gas embedded in massive clouds of dark matter.

    Data from Chandra, Hubble, Spitzer and other telescopes are part of the Frontier Fields project.

    NASA/ESA Hubble Telescope

    NASA/Spitzer Infrared Telescope

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

    This Frontier Fields galaxy cluster, known as MACS J1149.5+2233, is located about 5 billion light years from Earth.

    MACS J1149.5+2233 (MACS J1149 for short) is a system of merging galaxy clusters located about 5 billion light years from Earth. This galaxy cluster was one of six that have been studied as part of the “Frontier Fields” project. This research effort included long observations of galaxy clusters with powerful telescopes that detected different types of light, including NASA’s Chandra X-ray Observatory.

    Frontier Fields

    Astronomers are using the Frontier Fields data to learn more about how galaxy clusters grow via collisions. Galaxy clusters are enormous collections of hundreds or even thousands of galaxies and vast reservoirs of hot gas embedded in massive clouds of dark matter, invisible material that does not emit or absorb light but can be detected through its gravitational effects.

    This new image of MACS J1149 combines X-rays from Chandra (diffuse blue), optical data from Hubble (red, green, blue), and radio emission from the Very Large Array (pink). The image is about four million light years across at the distance of MACS J1149.

    The Chandra data reveal gas in the merging clusters with temperatures of millions of degrees. The optical data show galaxies in the clusters and other, more distant, galaxies lying behind the clusters. Some of these background galaxies are highly distorted because of gravitational lensing, the bending of light by massive objects. This effect can also magnify the light from these objects, enabling astronomers to study background galaxies that would otherwise be too faint to detect. Finally, the structures in the radio data trace enormous shock waves and turbulence. The shocks are similar to sonic booms, and are generated by the mergers of smaller clusters of galaxies.

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 1:17 pm on October 27, 2017 Permalink | Reply
    Tags: , , , , , Karl V Jansky NRAO VLA, ,   

    From astrobites: “Observing a Strange Pulsar in X-ray and Radio” 

    Astrobites bloc

    astrobites

    27 October 2017
    Joshua Kerrigan

    Title: Simultaneous Chandra and VLA Observations of the Transitional Millisecond Pulsar PSR J1023+0038: Anti-correlated X-ray and Radio Variability
    Authors: Slavko Bogdanov, Adam T. Deller, James C. A. Miller-Jones, et al.
    First Author’s Institution: Columbia University

    Status: Submitted to ApJ, open access

    What’s more interesting than a rapidly spinning neutron star that emits electromagnetic radiation parallel to its magnetic poles? One that doesn’t exactly behave as expected, of course. One such weirdly acting pulsar, PSR J1023+0038, is a transitional millisecond pulsar (tMSP) — which is fancy speak for a pulsar with a millisecond rotational period that switches between radio and X-ray emission on a several-year timescale. The fact that this pulsar emits in both X-ray and radio on these longer timescales isn’t what piques the interest of astronomers, however, in the case of the study in this astrobite.

    Weird Pulsar Behavior

    Pulsars can typically fall into one of the following categories: radio pulsars are powered by exchanging rotational energy from the spinning neutron star into emitting radiation. This means that their rotation slows and their pulse length increases. Meanwhile, X-ray pulsars are accretion powered, meaning they turn heated infalling matter into X-ray emission. What distinguishes PSR J1023+0038 from the background of pulsars that switch between accretion-powered X-ray and rotation-powered radio pulsars is that it has a simultaneous anti-correlated X-ray and radio emission. The authors looked at about 5 hours of overlapping and concurrent observations from the Chandra X-ray Observatory and the Very Large Array (VLA) to try and understand this weird relationship between the X-ray and radio emissions.

    NASA/Chandra Telescope

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

    This is very clearly shown in Fig. 1 where we can see a tiny sample of time of overlapping X-ray and radio flux measurements. The anti-correlation is quite strong, meaning that when the X-ray emissions are weakest, the radio emission is strongest.

    1
    Figure 1: Radio emissions (black) and x-ray emissions (blue) recorded by the VLA and Chandra respectively over time. This shows that when radio emissions drop off, X-ray emissions pick up.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
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