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  • richardmitnick 4:23 pm on September 22, 2017 Permalink | Reply
    Tags: A mini-halo is a faint diffuse region of radio emission that surrounds a cluster of galaxies, , Karl V Jansky NRAO VLA, Nature of Galaxy Cluster Mini-Halos,   

    From CfA: “Nature of Galaxy Cluster Mini-Halos” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    1
    A galaxy cluster mini-halo as seen around the galaxy NGC 1275 in the radio, with its main structures labeled: the northern extension, the two eastern spurs, the concave edge to the south, the south-western edge and a plume of emission to the south-south-west. Astronomers used radio and X-ray data to conclude that mini-halos, rather than being simple structures resulting from turbulence, are actually the result of multiple processes. Gendron-Marsolais et al.

    A mini-halo is a faint, diffuse region of radio emission that surrounds a cluster of galaxies. So far about thirty of these cluster mini-halos have been detected via their X-ray and radio emission, the result of radiation from electrons in the ionized gas, including one mini-halo in the nearby Perseus cluster of galaxies. These electrons are thought to arise from activity around a supermassive black hole at a galactic nucleus, which injects steams of particles into the intracluster medium and which also produces turbulence and shocks. One issue puzzling astronomers is that such electrons should rapidly lose their energy, faster than the time it takes for them to reach the mini-halo regions. Suggested solutions include processes in which turbulence reaccelerates the electrons, and in which cosmic rays generate new ones.

    CfA astronomer Reinout van Weeren and his colleagues used the radio Karl G. Jansky Very Large Array (JVLA) to obtain the first detailed study of the structure of the mini-halo in Perseus, and to compare it with Chandra X-Ray images.

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

    NASA/Chandra Telescope

    They find that the radio emission comes primarily from gas behind a cold front as would be expected if the gas is sloshing around within the cluster as particles are re-accelerated. They also detect unexpected, filamentary structures that seem to be associated with edges of X-ray features. The scientists conclude that mini-halos are not simply diffuse structures produced by a single process, but reflect a variety of structures and processes including turbulent re-acceleration of electrons, relativistic activity from the black hole jets, and also some magnetic field effects. Not least, the results demonstrate the sensitivity of the new JVLA and the need to obtain such sensitive images to understand the mini-halo phenomenon.

    Reference(s):

    Deep 230–470 MHz VLA Observations of the Mini-Halo in the Perseus Cluster, M. Gendron-Marsolais, J. Hlavacek-Larrondo, R. J. van Weeren, T. Clarke, A. C. Fabian, H. T. Intema, G. B. Taylor, K. M. Blundell, and J. S. Sanders, MNRAS 469, 3872, 2017.

    See the full article here .

    Please help promote STEM in your local schools.

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    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 5:14 pm on July 16, 2017 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA,   

    NRAO VLA, Courtesy of Juan Carlos, Magical Universe 

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

    The very large array or Karl V Jansky VLA is an observatory located on the plains of st. Augustine, between the towns of Magdalena and Datil, about 80 km west of Socorro, New Mexico, United States. The VLA is located at an altitude of 6970 ft [2.124] meters above sea level. It is part of the National Radio Observatory Observatory (NSF/NRAO), operated under cooperative agreement by Associated Universities, Inc. The Observatory consists of 27 independent antennas, each of which has a disc diameter of 25 metres and a weight of 209 tonnes. The antennae are aligned along three arms in the form of a Y-shaped array, and each arm is 21 miles. Using the railway tracks that follow each of these arms and a specially designed locomotive, the antennae can be physically relocated to a number of prepared positions, allowing with a maximum base of 36 km. Essentially the alignment acts as the only radio telescope with that diameter. The Highest Angular resolution that can be reached is about 0.05 seconds of arc.

    There are four commonly used settings, called a (the major) to d (the minor), the minor configuration is when all the disks are less than 600 m from the central point. The Observatory normally passes through all possible configurations (including some hybrids) every 16 months, in other words, once the incredible effort needed to move two dozen highly sensitive scientific instruments of 209 tons has been carried out, Antennas are not moved again for a period of about three to four months. The also serves as a control centre for the Very Long Baseline Array (VLBA).

    NRAO/VLBA

    NRAO/VLBA

     
  • richardmitnick 2:13 pm on July 6, 2017 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA, , Star’s Birth May Have Triggered Another Star Birth Astronomers Say   

    From NRAO: “Star’s Birth May Have Triggered Another Star Birth, Astronomers Say” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    June 20, 2017
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have found new evidence suggesting that a jet of fast-moving material ejected from one young star may have triggered the formation of another, younger protostar.

    1

    Protostar FIR 3 (HOPS 370) with outflow that may have triggered the formation of younger protostar FIR 4 (HOPS 108, location marked with red dot), in the Orion star-forming region. (au = astronomical unit, the distance from the Earth to the Sun, about 93 million miles.)
    Credit: Osorio et al., NRAO/AUI/NSF.

    2

    Protostar FIR 3 (HOPS 370) with outflow that may have triggered the formation of younger protostar FIR 4 (HOPS 108), in the Orion star-forming region. Pullouts are individual VLA images of each protostar. (au = astronomical unit, the distance from the Earth to the Sun, about 93 million miles.)
    Credit: Osorio et al., NRAO/AUI/NSF.

    “The orientation of the jet, the speed of its material, and the distance all are right for this scenario,” said Mayra Osorio, of the Astrophysical Institute of Andalucia (IAA-CSIC) in Spain. Osorio is the lead author of a paper reporting the findings in the Astrophysical Journal.

    The scientists studied a giant cloud of gas some 1,400 light-years from Earth in the constellation Orion, where numerous new stars are being formed. The region has been studied before, but Osorio and her colleagues carried out a series of VLA observations at different radio frequencies that revealed new details.

    Images of the pair show that the younger protostar, called HOPS (Herschel Orion Protostar Survey) 108, lies in the path of the outflow from the older, called HOPS 370. This alignment led Yoshito Shimajiri and collaborators to suggest in 2008 that the shock of the fast-moving material hitting a clump of gas had triggered the clump’s collapse into a protostar.

    “We found knots of material within this outflow and were able to measure their speeds,” said Ana K. Diaz-Rodriguez also of IAA-CSIC.

    The new measurements gave important support to the idea that the older star’s outflow had triggered the younger’s star’s formation process.

    The scientists suggest that the jet from HOPS 370 (also known as FIR 3) began to hit the clump of gas about 100,000 years ago, starting the process of collapse that eventually led to the formation of HOPS 108 (also known as FIR 4). Four other young stars in the region also could be the result of similar interactions, but the researchers found evidence for shocks only in the case of HOPS 108.

    While the evidence for this triggering scenario is strong, one fact appears to contradict it. The younger star seems to be moving rapidly in a way that indicates it should have been formed elsewhere, apart from the region impacted by the older star’s outflow.

    “This motion, however, might be an illusion possibly created by an outflow from the newer star itself,” explained Osorio. “We want to continue to observe it over a period of time to resolve this question,” she added.

    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 .

    Please help promote STEM in your local schools.

    STEM Icon

    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).

     
  • richardmitnick 1:44 pm on July 6, 2017 Permalink | Reply
    Tags: , , , , Karl V Jansky NRAO VLA, , , VLA Gives New Insight Into Galaxy Cluster’s Spectacular 'Mini-Halo'   

    From NRAO: “VLA Gives New Insight Into Galaxy Cluster’s Spectacular ‘Mini-Halo'” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    June 13, 2017
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    1

    Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have discovered new details that are helping them decipher the mystery of how giant radio-emitting structures are formed at the center of a cluster of galaxies.

    The scientists studied a cluster of thousands of galaxies more than 250 million light-years from Earth, named the Perseus Cluster after the constellation in which it appears. Embedded within the center, the Perseus Cluster hosts a pool of superfast particles that emit radio waves, creating a radio structure known as a “mini-halo.” Mini-haloes have been found in about 30 galaxy clusters, but the halo in the Perseus Cluster is the largest known, about 1.3 million light-years in diameter, or 10 times the size of our Milky Way Galaxy.

    The sizes of the mini-haloes have presented a puzzle to astronomers. As the particles travel away from the cluster’s center, they should slow down and stop emitting radio waves long before they reach the distances observed, according to theory.

    “At large distances from the central galaxy, we don’t expect to be able to see these haloes,” said Marie-Lou Gendron-Marsolais, of the University of Montreal. “However, we do see them and we want to know why,” she added.

    The astronomers took advantage of the upgraded capabilities of the VLA to make new images of the Perseus Cluster that were both more sensitive to fainter radio emissions and provided higher resolution than previous radio observations.

    “The new VLA images provided an unprecedented view of the mini-halo by revealing a multitude of new structures within it,” said Julie Hlavacek-Larrondo, also of the University of Montreal. “These structures tell us that the origin of the radio emission is not as simple as we thought,” she said.

    The new details indicate that the halo’s radio emission is caused by complex mechanisms that vary throughout the cluster. As theorized before, some radio emission is caused by particles being reaccelerated when small groups of galaxies collide with the cluster and give the particles a gravitational shove. In addition, however, the scientists now think that the radio emission is also caused by the powerful jets of particles generated by the supermassive black hole at the core of the central galaxy that give an extra “kick” of energy to the particles.

    “This would help explain the rich variety of complex structures that we see,” Gendron-Marsolais said.

    “The high-quality images that the upgraded VLA can produce will be key to helping us gain new insights into these mini-haloes in our quest to understand their origin,” Hlavacek-Larrondo said.

    The VLA, built during the 1970s, was equipped with all-new electronics to bring it up to the technological state of the art by a decade-long project completed in 2012. The images of the Perseus Cluster were made using a new low frequency receiver system funded by the Naval Research Laboratory (NRL) and built through collaboration between NRL and the National Radio Astronomy Observatory.

    Gendron-Marsolais and Hlavacek-Larrondo, along with an international team of researchers, are reporting their findings in the Monthly Notices of the Royal Astronomical Society.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    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).

     
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