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  • richardmitnick 5:34 pm on February 23, 2021 Permalink | Reply
    Tags: "Reclusive Neutron Star May Have Been Found in Famous Supernova", , , , , For decades scientists have searched for a neutron star in SN 1987A-i.e. a dense collapsed core that should have been left behind by the explosion., If this result is upheld by future observations it would confirm the existence of a neutron star in SN 1987A., NASA Chandra, , , , This latest study shows that a "pulsar wind nebula" created by such a neutron star may be present.   

    From NASA Chandra and From NASA NuSTAR: “Reclusive Neutron Star May Have Been Found in Famous Supernova” 

    NASA Chandra Banner

    NASA Chandra X-ray Space Telescope

    From NASA Chandra

    February 23, 2021

    Media contacts:
    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    Molly Porter
    Marshall Space Flight Center, Huntsville, Alabama
    256-544-0034
    molly.a.porter@nasa.gov

    Astronomers now have evidence from two X-ray telescopes (Chandra and NuSTAR) for a key component of a famous supernova remnant.

    NASA/DTU/ASI NuSTAR X-ray telescope.

    Supernova 1987A was discovered on Earth on February 24, 1987, making it the first such event witnessed during the telescopic age.

    SN 1987A remnant, imaged by ALMA. The inner region is contrasted with the outer shell, lacy white and blue circles, where the blast wave from the supernova is colliding with the envelope of gas ejected from the star prior to its powerful detonation. Image credit: ALMA / ESO / NAOJ / NRAO / Alexandra Angelich, NRAO / AUI / NSF.

    SN1987A. Credit: NASA/ESA Hubble Space Telescope in January, 2017 using its Wide Field Camera 3 (WFC3).

    NASA/ESA Hubble WFC3

    NASA/ESA Hubble Telescope.

    For decades, scientists have searched for a neutron star in SN 1987A, i.e. a dense collapsed core that should have been left behind by the explosion.

    This latest study shows that a “pulsar wind nebula” created by such a neutron star may be present.
    ________________________________________________________________________________________________________

    Astronomers have found evidence for the existence of a neutron star at the center of Supernova 1987A (SN 1987A), which scientists have been seeking for over three decades. As reported in our latest press release, SN 1987A was discovered on February 24, 1987. The panel on the left contains a 3D computer simulation, based on Chandra data, of the supernova debris from SN 1987A crashing into a surrounding ring of material. The artist’s illustration (right panel) depicts a so-called pulsar wind nebula, a web of particles and energy blown away from a pulsar, which is a rotating, highly magnetized neutron star. Data collected from NASA’s Chandra X-ray Observatory and NuSTAR in a new study support the presence of a pulsar wind nebula at the center of the ring.

    If this result is upheld by future observations, it would confirm the existence of a neutron star in SN 1987A, the collapsed core that astronomers expect would be present after the star exploded. The pulsar would also be the youngest one ever found.

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    NuSTAR and Chandra images of Supernova 1987A. Credit: NASA.

    When a star explodes, it collapses onto itself before the outer layers are blasted into space. The compression of the core turns it into an extraordinarily dense object, with the mass of the Sun squeezed into an object only about 10 miles across. Neutron stars, as they were dubbed because they are made nearly exclusively of densely packed neutrons, are laboratories of extreme physics that cannot be duplicated here on Earth. Some neutron stars have strong magnetic fields and rotate rapidly, producing a beam of light akin to a lighthouse. Astronomers call these objects “pulsars,” and they sometimes blow winds of charged particles that can create pulsar wind nebulas.

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

    With Chandra and NuSTAR, the team found relatively low-energy X-rays from the supernova debris crashing into surrounding material. The team also found evidence of high-energy particles, using NuSTAR’s ability to detect higher-energy X-rays.

    There are two likely explanations for this energetic X-ray emission: either a pulsar wind nebula, or particles being accelerated to high energies by blast wave of the explosion. The latter effect doesn’t require the presence of a pulsar and occurs over much larger distances from the center of the explosion.

    The latest X-ray study supports the case for the pulsar wind nebula on a couple of fronts. First, the brightness of the higher energy X-rays remained about the same between 2012 and 2014, while the radio emission increased. This goes against expectations in the scenario of energetic particles in the explosion debris. Next, authors estimate it would take almost 400 years to accelerate the electrons up to the highest energies seen in the NuSTAR data, which is over ten times older than the age of the remnant.

    The Chandra and NuSTAR data also support a 2020 result from the Atacama Large Millimeter Array (ALMA) that provided possible evidence for the structure of a pulsar wind nebula in the radio band.

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

    While this “blob” had other potential explanations, its identification as a pulsar wind nebula could be substantiated with the new X-ray data.

    The center of SN 1987A is surrounded by gas and dust. The authors used state-of-the-art simulations to understand how this material would absorb X-rays at different energies, enabling more accurate interpretation of the X-ray spectrum, that is, the spread of X-rays over wavelength. This enables them to estimate what the spectrum of the central regions of SN 1987A is without the obscuring material.

    A paper describing these results is being published this week in The Astrophysical Journal Letters. The authors of the paper are Emanuele Greco and Marco Miceli (University of Palermo[Università degli Studi di Palermo](IT)), Salvatore Orlando, Barbara Olmi and Fabrizio Bocchino (Palermo Astronomical Observatory[Giuseppe S. Vaiana Astronomical Observatory](IT), an Italian National Institute for Astrophysics [Istituto Nazionale di Astrofisica](IT) research facility); Shigehiro Nagataki and Masaomi Ono (Astrophysical Big Bang Laboratory, RIKEN Institute of Physical and Chemical Research [Kokuritsu Kenkyū Kaihatsu Hōjin Rikagaku Kenkyūsho (国立研究開発法人理化学研究所](JP) ); Akira Dohi (Kyushu University[九州大学, Kyūshū Daigaku](JP), and Giovanni Peres (University of Palermo).

    NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory for the agency’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Technical University of Denmark[Danmarks Tekniske Universitet](DK) and the ASI Italian Space Agency [Agenzia Spaziale Italiana](IT). The spacecraft was built by Orbital Sciences Corporation in Dulles, Virginia(US) (now part of Northrop Grumman). NuSTAR’s mission operations center is at UC Berkeley(US), and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center(US). ASI provides the mission’s ground station and a mirror archive. JPL is a division of Caltech.


    Quick Look: Supernova 1987A Pulsar Wind Nebula

    See the full article here.


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    NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory for the agency’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Technical University of Denmark[Danmarks Tekniske Universitet](DK) and the ASI Italian Space Agency [Agenzia Spaziale Italiana](IT). The spacecraft was built by Orbital Sciences Corporation in Dulles, Virginia(US) (now part of Northrop Grumman). NuSTAR’s mission operations center is at UC Berkeley(US), and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center(US). ASI provides the mission’s ground station and a mirror archive. JPL is a division of Caltech.


    NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

    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 11:49 am on February 23, 2021 Permalink | Reply
    Tags: "Ultramassive black hole in NGC 1600 investigated in detail", , , , Bondi radius—a calculated radius of the region around the galaxy from which surrounding medium is likely to be drawn in and accreted., , NASA Chandra, NGC 1600 hosts an extremely massive black hole—with mass estimated to reach 17 billion solar masses., NGC 1600 is an elliptical galaxy in the constellation Eridanus., , University of Alabama in Huntsville(US)   

    From phys.org: “Ultramassive black hole in NGC 1600 investigated in detail” 


    From phys.org

    February 22, 2021
    Tomasz Nowakowski

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    Smoothed soft band (0.5 – 1.2 keV) Chandra image of NGC 1600. Credit: James Runge and Stephen A. Walker, 2021.

    Using NASA’s Chandra X-ray observatory, astronomers from the University of Alabama in Huntsville(US) have investigated the central region of the galaxy NGC 1600, focusing on its ultramassive black hole (UMBH).

    NASA Chandra X-ray Space Telescope.

    Results of the study, presented in a paper published February 11 in MNRAS shed more light on the properties of this UMBH.

    At a distance of about 150,000,000 light years away from the Earth, NGC 1600 is an elliptical galaxy in the constellation Eridanus. It has a mass of around 1 trillion solar masses, and despite the fact that it belongs to a relatively small group of only a few galaxies, NGC 1600 hosts an extremely massive black hole—with mass estimated to reach 17 billion solar masses.

    The properties of the UMBH in NGC 1600, especially its huge mass and relatively close proximity, make it an excellent target for which spatially resolved temperature and density profiles can be obtained within the Bondi radius—a calculated radius of the region around the galaxy from which surrounding medium is likely to be drawn in and accreted. Hence, University of Alabama’s James Runge and Stephen A. Walker decided to employ Chandra in order to conduct such study.

    “Using new deep Chandra observations in conjunction with archival Chandra data of NGC 1600, we have determined the temperature and density profiles within the Bondi accretion radius, down to a radius of ∼0.16 kpc from the central ultramassive black hole,” the researchers wrote in the paper.

    The study analyzed the hot gas properties within the Bondi accretion radius (estimated to be between 1,240 and 1,760 light years. The researchers detected two statistically significant temperature components within 9,780 light years and found that the temperature profile increases very mildly within the Bondi radius.

    The findings are surprising, as they are in contrast with the expected increase in temperature towards the center one would expect from classical Bondi accretion, which suggests that the dynamics of the gas are not being determined by the black hole. However, the astronomers noted that there is a possibility that the temperature increases on scales smaller than those that can be investigated.

    The mass accretion rate at the Bondi radius was calculated to be at a level of about 0.1-0.2 solar masses per year. The researchers found that inside the Bondi radius, the density profile follows a power law flatter than expected for classical Bondi accretion.

    “The density profile follows a relatively shallow ρ ∝ r−[0.61±0.13] relationship within the Bondi radius, which suggests that the true accretion rate on to the black hole may be lower than the classical Bondi accretion rate,” the astronomers explained.

    The research also found that the calculated entropy drops below a critical value of 30 keV cm2 within 9,800 light years, what is characteristic for systems with thermal instabilities.

    See the full article here .

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    Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
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  • richardmitnick 3:09 pm on February 8, 2021 Permalink | Reply
    Tags: "Rare blast's remains discovered in Milky Way's center", , , , , , NASA Chandra, NRAO Karl G Jansky Very Large Array   

    From Harvard-Smithsonian Center for Astrophysics via phys.org: “Rare blast’s remains discovered in Milky Way’s center” 



    From Harvard-Smithsonian Center for Astrophysics

    via


    phys.org

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    This composite image of X-ray data from Chandra (blue) and radio emission from the Very Large Array (red) contains the first evidence for a rare type of supernova in the Milky Way. By analyzing over 35 days’ worth of Chandra observations, researchers found an unusual pattern of elements such as iron and nickel in the stellar debris. The leading explanation is that this supernova remnant, called Sgr A East, was generated by a so-called Type Iax supernova. This is a special class of Type Ia supernova explosions that are used to accurately measure distances across space and study the expansion of the Universe. Credit: X-ray: NASA/CXC/Nanjing Univ./P. Zhou et al. Radio: NSF/NRAO/VLA.

    NASA Chandra X-ray Space Telescope.

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

    Astronomers may have found our galaxy’s first example of an unusual kind of stellar explosion. This discovery, made with NASA’s Chandra X-ray Observatory, adds to the understanding of how some stars shatter and seed the universe with elements critical for life on Earth.

    This intriguing object, located near the center of the Milky Way, is a supernova remnant called Sagittarius A East, or Sgr A East for short. Based on Chandra data, astronomers previously classified the object as the remains of a massive star that exploded as a supernova, one of many kinds of exploded stars that scientists have cataloged.

    Using longer Chandra observations, a team of astronomers has now instead concluded that the object is left over from a different type of supernova. It is the explosion of a white dwarf, a shrunken stellar ember from a fuel-depleted star like our Sun. When a white dwarf pulls too much material from a companion star or merges with another white dwarf, the white dwarf is destroyed, accompanied by a stunning flash of light.

    Astronomers use these “Type Ia supernovae” because most of them mete out almost the same amount of light every time no matter where they are located. This allows scientists to use them to accurately measure distances across space and study the expansion of the universe.


    Quick Look: Sagittarius A East.

    Data from Chandra have revealed that Sgr A East, however, did not come from an ordinary Type Ia. Instead, it appears that it belongs to a special group of supernovae that produce different relative amounts of elements than traditional Type Ias do, and less powerful explosions. This subset is referred to as “Type Iax,” a potentially important member of the supernova family.

    “While we’ve found Type Iax supernovae in other galaxies, we haven’t identified evidence for one in the Milky Way until now,” said Ping Zhou of Nanjing University in China, who led the new study while at the University of Amsterdam. “This discovery is important for getting a handle of the myriad ways white dwarfs explode.”

    The explosions of white dwarfs is one of the most important sources in the universe of elements like iron, nickel, and chromium. The only place that scientists know these elements can be created is inside the nuclear furnace of stars or when they explode.

    “This result shows us the diversity of types and causes of white dwarf explosions, and the different ways that they make these essential elements,” said co-author Shing-Chi Leung of Caltech in Pasadena, California. “If we’re right about the identity of this supernova’s remains, it would be the nearest known example to Earth.”

    Astronomers are still debating the cause of Type Iax supernova explosions, but the leading theory is that they involve thermonuclear reactions that travel much more slowly through the star than in Type Ia supernovae. This relatively slow walk of the blast leads to weaker explosions and, hence, different amounts of elements produced in the explosion. It is also possible that part of the white dwarf is left behind.

    Sgr A East is located very close to Sagittarius A*, the supermassive black hole in the center of our Milky Way galaxy, and likely intersects with the disk of material surrounding the black hole. The team was able to use Chandra observations targeting the supermassive black hole and the region around it for a total of about 35 days to study Sgr A East and find the unusual pattern of elements in the X-ray data. The Chandra results agree with computer models predicting a white dwarf that has undergone slow-moving nuclear reactions, making it a strong candidate for a Type Iax supernova remnant.

    “This supernova remnant is in the background of many Chandra images of our galaxy’s supermassive black hole taken over the last 20 years,” said Zhiyuan Li, also of Nanjing University. “We finally may have worked out what this object is and how it came to be.”

    In other galaxies, scientists observe that Type Iax supernovae occur at a rate that is about one third that of Type Ia supernovae. In the Milky Way, there have been three confirmed Type Ia supernova remnants and two candidates that are younger than 2,000 years, corresponding to an age when remnants are still relatively bright before fading later. If Sgr A East is younger than 2,000 years and resulted from a Type Iax supernova, this study suggests that our galaxy is in alignment with respect to the relative numbers of Type Iax supernovae seen in other galaxies.

    Along with the suggestion that Sgr A East is the remnant from the collapse of a massive star, previous studies have also pointed out that a normal Type Ia supernova had not been ruled out. The latest study conducted with this deep Chandra data argue against both the massive star and the normal Type Ia interpretations.

    These results will be published on Wednesday February 10th, 2021 in The Astrophysical Journal.

    See the full article here .


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

     
  • richardmitnick 5:15 pm on January 14, 2021 Permalink | Reply
    Tags: "Galaxies Hit Single; Doubles; and a Triple (Growing Black Holes)", A new study looked at triple galaxy mergers to learn what happens to their supermassive black holes., , , , , NASA Chandra   

    From NASA Chandra: “Galaxies Hit Single; Doubles; and a Triple (Growing Black Holes)” 

    NASA Chandra Banner

    NASA Chandra X-ray Space Telescope

    From NASA Chandra

    January 14, 2021

    Media contacts:
    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    Molly Porter
    Marshall Space Flight Center, Huntsville, Alabama
    256-544-0034
    molly.a.porter@nasa.gov

    X-ray: NASA/CXC/Univ. of Michigan/A. Foord et al.; Optical: SDSS & NASA/STScI.

    A new study looked at triple galaxy mergers to learn what happens to their supermassive black holes.

    The results find a single, four doubles, a triple giant black hole remain in six of the seven mergers.

    A team used several telescopes including Chandra plus specially-developed software to identify these growing black holes.

    This helps astronomers better understand what role mergers play in how galaxies and their giant black holes grow.

    A new study helps reveal what happens to supermassive black holes when three galaxies merge, as reported in our latest press release. This result, which used data from NASA’s Chandra X-ray Observatory and several other telescopes, tells astronomers more about how galaxies and the giant black holes in their centers grow over cosmic time.

    While there have been previous studies of mergers between two galaxies, this is one of the first to systematically look at the consequences for supermassive black holes when three galaxies come together. This panel of images contains data from two of seven galactic collisions in the new study containing two supermassive black holes left growing after the collision. The pair of mergers are seen in X-rays from Chandra (left in purple) and optical data (right) from NASA’s Hubble Space Telescope and the Sloan Digital Sky Survey (SDSS). Circles in a labeled version of the Chandra image show X-rays from hot gas falling towards each black hole.

    NASA/ESA Hubble Telescope.

    SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude2,788 meters (9,147 ft).

    Apache Point Observatory, near Sunspot, New Mexico Altitude 2,788 meters (9,147 ft).

    These triple galaxy mergers were first identified by sifting through data from the SDSS and NASA’s WISE mission and then comparing the results to X-ray data in the Chandra archive.

    NASA/WISE NEOWISE Telescope.

    This method identified seven triple galaxy mergers located between 370 million and one billion light years from Earth.

    Using specialized software, the team went through Chandra data targeting these systems to detect X-ray sources marking the location of growing supermassive black holes. As material falls toward a black hole, it gets heated to millions of degrees and produces X-rays. The combination of the new software and Chandra’s sharp X-ray vision enabled the researchers to identify the black holes despite their close proximity in the images.

    Out of seven triple galaxy mergers, the results are: one with a single growing supermassive black hole, four with double growing supermassive black holes (two of which are shown in the main graphics), and one that is a triple. The final merger of three galaxies they studied seems to have no X-ray emission detected from the supermassive black holes. This means that none of the supermassive black holes were left rapidly pulling in matter. In the systems with multiple black holes, the separations between them range between about 10,000 and 30,000 light years.

    Once they found evidence for bright X-ray sources as candidates for growing supermassive black holes in the Chandra data, the researchers incorporated archival data from other telescopes such as WISE mission, the Infrared Astronomical Satellite, and the Two Micron All Sky Telescope as another check in the process.


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

    NASA/UK/NL Infrared Astronomical Survey IRAS spacecraft

    Studies of triple mergers can help scientists understand whether pairs of supermassive black holes can approach so close to each other that they make ripples in spacetime called gravitational waves. The energy lost by these waves will inevitably cause the black holes to merge.

    Adi Foord presented the new study, which she worked on as part of her Ph.D. at the University of Michigan, at the 237th meeting of the American Astronomical Society, which is being held virtually from January 11-15, 2021. Two papers describing this work have recently been accepted for publication in The Astrophysical Journal and preprints are available here and here.


    A Quick Look at Triple Galaxy Mergers

    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 3:46 pm on January 8, 2021 Permalink | Reply
    Tags: "J1818.0-1607- Chandra Studies Extraordinary Magnetar", , , , , NASA Chandra, The fastest spinning and possibly the youngest magnetar known.   

    From NASA Chandra: “J1818.0-1607- Chandra Studies Extraordinary Magnetar” 

    NASA Chandra Banner

    NASA Chandra X-ray Space Telescope

    From NASA Chandra

    January 8, 2021

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    Composite

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    X-ray

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    Infrared

    Astronomers have recently found the fastest spinning and possibly the youngest magnetar known.

    This object, known as J1818.0-1607, is located about 21,000 light years away in the Milky Way galaxy.

    Magnetars are a special class of neutron stars that possess extremely powerful magnetic fields.

    Researchers used Chandra and other telescopes to learn about the unusual properties of this object.

    In 2020, astronomers added a new member to an exclusive family of exotic objects with the discovery of a magnetar. New observations from NASA’s Chandra X-ray Observatory help support the idea that it is also a pulsar, meaning it emits regular pulses of light.

    Magnetars are a type of neutron star, an incredibly dense object mainly made up of tightly packed neutrons, which forms from the collapsed core of a massive star during a supernova.

    What sets magnetars apart from other neutron stars is that they also have the most powerful known magnetic fields in the Universe. For context, the strength of our planet’s magnetic field has a value of about one Gauss, while a refrigerator magnet measures about 100 Gauss. Magnetars, on the other hand, have magnetic fields of about a million billion Gauss. If a magnetar was located a sixth of the way to the Moon (about 40,000 miles), it would wipe the data from all of the credit cards on Earth.

    On March 12, 2020, astronomers detected a new magnetar with NASA’s Neil Gehrels Swift Telescope. This is only the 31st known magnetar, out of the approximately 3,000 known neutron stars.

    NASA Neil Gehrels Swift Observatory.

    After follow-up observations, researchers determined that this object, dubbed J1818.0-1607, was special for other reasons. First, it may be the youngest known magnetar, with an age estimated to be about 500 years old. This is based on how quickly the rotation rate is slowing and the assumption that it was born spinning much faster. Secondly, it also spins faster than any previously discovered magnetar, rotating once around every 1.4 seconds.

    Chandra’s observations of J1818.0-1607 obtained less than a month after the discovery with Swift gave astronomers the first high-resolution view of this object in X-rays. The Chandra data revealed a point source where the magnetar was located, which is surrounded by diffuse X-ray emission, likely caused by X-rays reflecting off dust located in its vicinity. (Some of this diffuse X-ray emission may also be from winds blowing away from the neutron star.)

    4
    Close-Up Image of J1818.0-1607 (Credit: X-ray: NASA/CXC/Univ. of West Virginia/H. Blumer; Infrared (Spitzer and Wise): NASA/JPL-CalTech/Spitzer)

    NASA/Spitzer Infrared telescope no longer in service. Launched in 2003 and retired on 30 January 2020. Credit: NASA.

    NASA/WISE NEOWISE Telescope.

    Harsha Blumer of West Virginia University and Samar Safi-Harb of the University of Manitoba in Canada recently published results from the Chandra observations of J1818.0-1607 in The Astrophysical Journal Letters.

    This composite image contains a wide field of view in the infrared from two NASA missions, the Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer (WISE), taken before the magnetar’s discovery. X-rays from Chandra show the magnetar in purple. The magnetar is located close to the plane of the Milky Way galaxy at a distance of about 21,000 light years from Earth.

    Other astronomers have also observed J1818.0-1607 with radio telescopes, such as the NSF’s Karl Jansky Very Large Array (VLA), and determined that it gives off radio waves.

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

    This implies that it also has properties similar to that of a typical “rotation-powered pulsar,” a type of neutron star that gives off beams of radiation that are detected as repeating pulses of emission as it rotates and slows down. Only five magnetars including this one have been recorded to also act like pulsars, constituting less than 0.2% of the known neutron star population.

    The Chandra observations may also provide support for this general idea. Safi-Harb and Blumer studied how efficiently J1818.0-1607 is converting energy from its decreasing rate of spin into X-rays. They concluded this efficiency is lower than that typically found for magnetars, and likely within the range found for other rotation-powered pulsars.

    The explosion that created a magnetar of this age would be expected to have left behind a detectable debris field. To search for this supernova remnant, Safi-Harb and Blumer looked at the X-rays from Chandra, infrared data from Spitzer, and the radio data from the VLA. Based on the Spitzer and VLA data they found possible evidence for a remnant, but at a relatively large distance away from the magnetar. In order to cover this distance the magnetar would need to have traveled at speeds far exceeding those of the fastest known neutron stars, even assuming it is much older than expected, which would allow more travel time.


    Quick Look: Chandra Studies Extraordinary Magnetar

    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 10:01 pm on December 18, 2020 Permalink | Reply
    Tags: "Abell 2261- On the Hunt for a Missing Giant Black Hole", , , , , NASA Chandra,   

    From NASA Chandra: “Abell 2261- On the Hunt for a Missing Giant Black Hole” 

    NASA Chandra Banner

    NASA Chandra X-ray Space Telescope

    From NASA Chandra

    December 17, 2020

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    Composite

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    X-ray

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    Optical/Infrared

    Credit X-ray: NASA/CXC/Univ of Michigan/K. Gültekin; Optical: NASA/STScI and NAOJ/Subaru; Infrared: NSF/NOAO/KPNO.

    Astronomers are searching for signs of a supermassive black hole in the galaxy cluster Abell 2261.

    Nearly all large galaxies contain central black holes, and the galaxy in the middle of Abell 2261 is expected to contain a particularly massive one.

    Scientists think this galaxy underwent a merger with another galaxy in the past, which could have caused a newly formed larger black hole to be ejected.

    Despite careful searches with Chandra and other telescopes, astronomers do not yet know what happened to this giant black hole.

    The mystery surrounding the whereabouts of a supermassive black hole has deepened.

    Despite searching with NASA’s Chandra X-ray Observatory and Hubble Space Telescope, astronomers have no evidence that a distant black hole estimated to weigh between 3 billion and 100 billion times the mass of the Sun is anywhere to be found.

    This missing black hole should be in the enormous galaxy in the center of the galaxy cluster Abell 2261, which is located about 2.7 billion light years from Earth. This composite image of Abell 2261 contains optical data from Hubble and the Subaru Telescope showing galaxies in the cluster and in the background, and Chandra X-ray data showing hot gas (colored pink) pervading the cluster. The middle of the image shows the large elliptical galaxy in the center of the cluster.

    Nearly every large galaxy in the Universe contains a supermassive black hole in their center, with a mass that is millions or billions of times that of the Sun. Since the mass of a central black hole usually tracks with the mass of the galaxy itself, astronomers expect the galaxy in the center of Abell 2261 to contain a supermassive black hole that rivals the heft of some of the largest known black holes in the Universe.

    Using Chandra data obtained in 1999 and 2004 astronomers had already searched the center of Abell 2261’s large central galaxy for signs of a supermassive black hole. They looked for material that has been superheated as it fell towards the black hole and produced X-rays, but did not detect such a source.

    Now, with new, longer Chandra observations obtained in 2018, a team led by Kayhan Gultekin from the University of Michigan in Ann Arbor conducted a deeper search for the black hole in the center of the galaxy. They also considered an alternative explanation, in which the black hole was ejected from the host galaxy’s center. This violent event may have resulted from two galaxies merging to form the observed galaxy, accompanied by the central black hole in each galaxy merging to form one enormous black hole.

    When black holes merge, they produce ripples in spacetime called gravitational waves. If the huge amount of gravitational waves generated by such an event were stronger in one direction than another, the theory predicts that the new, even more massive black hole would have been sent careening away from the center of the galaxy in the opposite direction. This is called a recoiling black hole.

    Astronomers have not found definitive evidence for recoiling black holes and it is not known whether supermassive black holes even get close enough to each other to produce gravitational waves and merge; so far, astronomers have only verified the mergers of much smaller black holes. The detection of recoiling supermassive black holes would embolden scientists using and developing observatories to look for gravitational waves from merging supermassive black holes.

    The galaxy at the center of Abell 2261 is an excellent cluster to search for a recoiling black hole because there are two indirect signs that a merger between two massive black holes might have taken place. First, data from the Hubble and Subaru optical observations reveal a galactic core — the central region where the number of stars in the galaxy in a given patch of the galaxy is at or close to the maximum value — that is much larger than expected for a galaxy of its size. The second sign is that the densest concentration of stars in the galaxy is over 2,000 light years away from the center of the galaxy, which is strikingly distant.

    These features were first identified by Marc Postman from Space Telescope Science Institute (STScI) and collaborators in their earlier Hubble and Subaru images, and led them to suggest the idea of a merged black hole in Abell 2261.

    NASA/ESA Hubble Telescope.

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

    During a merger, the supermassive black hole in each galaxy sinks toward the center of the newly coalesced galaxy.

    Artist’s iconic conception of two merging black holes similar to those detected by LIGO Credit LIGO-Caltech/MIT/Sonoma State /Aurore Simonnet.

    If they become bound to each other by gravity and their orbit begins to shrink, the black holes are expected to interact with surrounding stars and eject them from the center of the galaxy. This would explain Abell 2261’s large core. The off-center concentration of stars may also have been caused by a violent event such as the merger of two supermassive black holes and subsequent recoil of single, larger black hole that results.

    Even though there are clues that a black hole merger took place, neither Chandra nor Hubble data showed evidence for the black hole itself. Gultekin and most of his co-authors, led by Sarah Burke-Spolaor from West Virginia University, had previously used Hubble to look for a clump of stars that might have been carried off by a recoiling black hole. They studied three clumps near the center of the galaxy, and examined whether the motions of stars in these clumps are high enough to suggest they contain a ten billion solar mass black hole. No clear evidence for a black hole was found in two of the clumps and the stars in the other one were too faint to produce useful conclusions.

    They also previously studied observations of Abell 2261 with the NSF’s Karl G. Jansky Very Large Array.

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

    Radio emission detected near the center of the galaxy showed evidence that supermassive black hole activity had occurred there 50 million years ago, but does not indicate that the center of the galaxy currently contains such a black hole.

    4
    Credit: NASA/CXC, NASA/STScI, NAOJ/Subaru, NSF/NRAO/VLA

    They then turned to Chandra to look for material that had been superheated and produced X-rays as it fell towards the black hole. While the Chandra data did reveal that the densest hot gas was not in the center of the galaxy, they did not reveal any possible X-ray signatures of a growing supermassive black hole — no X-ray source was found in the center of the cluster, or in any of the clumps of stars, or at the site of the radio emission.

    The authors concluded that either there is no black hole at any of these locations, or that it is pulling material in too slowly to produce a detectable X-ray signal.

    The mystery of this gigantic black hole’s location therefore continues. Although the search was unsuccessful, hope remains for astronomers looking for this supermassive black hole in the future. Once launched, the James Webb Space Telescope may be able to reveal the presence of a supermassive black hole in the center of the galaxy or one of the clumps of stars. If Webb is unable to find the black hole, then the best explanation is that the black hole has recoiled well out of the center of the galaxy.

    A paper describing these results has been accepted for publication in a journal of the American Astronomical Society, and is also available online at https://arxiv.org/abs/2010.13980 [Chandra Observations of Abell 2261 Brightest Cluster Galaxy, a Candidate Host to a Recoiling Black Hole]. Gultekin’s co-authors are Sarah Burke-Spolaor; Tod R. Lauer (National Optical Infrared Astronomy Research Laboratory, Tucson, Arizona); T. Joseph W. Lazio and Leonidas A. Moustakas (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California); and Patrick Ogle and Marc Postman (Space Telescope Science Institute, Baltimore, Maryland).


    Quick Look: On the Hunt for a Missing Giant Black Hole.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 11:41 am on November 13, 2020 Permalink | Reply
    Tags: "Three high-redshift quasars detected by Chandra", , , , , NASA Chandra,   

    From NASA Chandra via phys.org: “Three high-redshift quasars detected by Chandra” 

    NASA Chandra Banner

    NASA Chandra X-ray Space Telescope

    From NASA Chandra

    via


    phys.org

    November 12, 2020
    Tomasz Nowakowski

    1
    0.5-7 keV Chandra counts images of the three quasars studied in the paper. Credit: Li et al., 2020.

    Using NASA’s Chandra spacecraft, astronomers have discovered three new ultraviolet-bright radio-quiet quasars at high redshift and measured their basic X-ray properties. The newly found quasi-stellar object turns out to be the brightest in UV among the known high-redshift radio-quiet quasars. The finding is presented in a paper published November 2 in The Astrophysical Journal.

    Quasars, or quasi-stellar objects (QSOs), are extremely luminous active galactic nuclei (AGN) containing supermassive central black holes with accretion disks. Their redshifts are measured from the strong spectral lines that dominate their visible and ultraviolet spectra.

    Astronomers are especially interested in finding new high-redshift quasars (at redshift higher than 5.0) as they are the most luminous and most distant compact objects in the observable universe. Spectra of such QSOs can be used to estimate the mass of supermassive black holes that constrain the evolution and formation models of quasars. Therefore, high-redshift quasars could serve as a powerful tool to probe the early universe.

    Recently, a team of astronomers led by Jiang-Tao Li of the University of Michigan, has used Chandra to conduct follow-up observations of very luminous radio quiet quasars. They found that three of them, designated J002526-014532, J074749+115352 and J220226+150952, are the UV brightest radio quiet ones detected at a redshift over 5.0.

    “In this paper, we present new Chandra observations of three UV bright quasars at z > 5,” the astronomers wrote in the paper.

    The three quasars reported in the study have a rest frame 2-10 keV luminosity of over 1 quattuordecillion erg/s and the X-ray power law photon index well constrained – in the range of 1.6 to 2.1. At a redshift of 5.26, J074749+115352 turned out to be the X-ray brightest radio-quiet high-redshift quasar, with an average observed X-ray flux at a level of 0.0349 picoergs/s/cm2.

    According to the study, the high X-ray flux of J074749+115352 makes it unique for timing analysis on a timescale of a few hours at such high redshift. The astronomers noted that there are two states in the X-ray variation of this quasar: a “high soft” state with an average X-ray flux of about 2.7 times greater than that of the “low hard” state. The mass of this quasar’s supermassive black hole was estimated to be about 1.82 billion solar masses.

    By comparing the newfound three quasars to other high-redshift objects of this type, the researchers underlined how much unique is J074749+115352.

    “We find that J074749+115352 is extraordinarily X-ray bright, with an average αOX = −1.46 ± 0.02 and 2-10 keV bolometric correction factor Lbol/L2−10keV = 42.4 ± 5.8; both significantly depart from some well defined scaling relations. This quasar also has a high Eddington ratio of λEdd = 2.25 ± 0.09,” the authors of the paper explained.

    However, they added that more X-ray and infrared observations are needed to confirm the nature and better understand the properties of this QSO.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 5:29 pm on November 12, 2020 Permalink | Reply
    Tags: "IC 4593: A Cosmic Amethyst in a Dying Star", , , , , NASA Chandra   

    From NASA Chandra: “IC 4593: A Cosmic Amethyst in a Dying Star” 

    NASA Chandra Banner

    NASA Chandra X-ray Space Telescope

    From NASA Chandra

    November 12, 2020

    Media contacts:
    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    1
    Composite

    2
    X-ray

    3
    Optical

    Chandra has found a bubble of ultra-hot gas at the center of a planetary nebula.

    Planetary nebulas are formed when Sun-like stars run out of fuel, shedding their outer layers while the star’s core shrinks.

    This image contains X-rays from Chandra (purple) and optical light data from Hubble (pink and green).

    IC 4593 is at a distance of about 7,800 light years from Earth, which is the farthest planetary nebula detected by Chandra.

    On Earth, amethysts can form when gas bubbles in lava cool under the right conditions. In space, a dying star with a mass similar to the Sun is capable of producing a structure on par with the appeal of these beautiful gems.

    As stars like the Sun run through their fuel, they cast off their outer layers and the core of the star shrinks. Using NASA’s Chandra X-ray Observatory, astronomers have found a bubble of ultra-hot gas at the center of one of these expiring stars, a planetary nebula in our galaxy called IC 4593. At a distance of about 7,800 light years from Earth, IC 4593 is the most distant planetary nebula yet detected with Chandra.

    This new image of IC 4593 has X-rays from Chandra in purple, invoking similarities to amethysts found in geodes around the globe. The bubble detected by Chandra is from gas that has been heated to over a million degrees. These high temperatures were likely generated by material that blew away from the shrunken core of the star and crashed into gas that had previously been ejected by the star.

    This composite image also contains visible light data from the Hubble Space Telescope (pink and green). The pink regions in the Hubble image are the overlap of emission from cooler gas composed of a combination of nitrogen, oxygen, and hydrogen, while the green emission is mainly from nitrogen.

    NASA/ESA Hubble Telescope.

    IC 4593 is what astronomers call a “planetary nebula,” a deceptive-sounding name because this class of objects has nothing to do with planets. (The name was given about two centuries ago because they looked like the disk of a planet when viewed through a small telescope.) In fact, a planetary nebula is formed after the interior of a star with about the mass of the Sun contracts and its outer layers expand and cool. In the case of the Sun, its outer layers could extend as far as the orbit of Venus during its red giant phase several billion years in the future.

    In addition to the hot gas, this study also finds evidence for point-like X-ray source at the center of IC 4593. This X-ray emission has higher energies than the bubble of hot gas. The point source could be from the star that discarded its outer layers to form the planetary nebula or it could be from a possible companion star in this system.

    A paper describing these results appears in the April 2020 issue of the MNRAS. The authors are Jesús A. Toalá (Instituto de Radioastronomía y Astrofísica (IRyA)(MX)); M. A. Guerrero (Instituto de Astrofísica de Andalucía (ES); L. Bianchi (The Johns Hopkins University, in Baltimore, Maryland); Y.-H. Chu (Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)(TW); and O. De Marco (Macquarie University (AU)).

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 2:49 pm on October 30, 2020 Permalink | Reply
    Tags: "Assessing The Habitability of Planets Around Old Red Dwarfs", , , , , , NASA Chandra   

    From NASA Chandra: “Assessing The Habitability of Planets Around Old Red Dwarfs” 

    NASA Chandra Banner

    NASA/Chandra Telescope


    From NASA Chandra

    October 30, 2020

    Media contacts:
    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    Molly Porter
    Marshall Space Flight Center, Huntsville, Alabama
    256-544-0034
    molly.a.porter@nasa.gov

    1

    How hospitable are red dwarf stars, the most common and long-lasting stars in our Galaxy?

    Researchers used Chandra and Hubble data to look at the intensity and frequency of high-energy flares from one nearby red dwarf.

    Barnard’s Star is one of the closest stars to Earth at a distance of only 6 light years.

    At its age of 10 billion years old, Barnard’s Star is still very active and potentially destructive for the atmospheres of any planets orbiting around it.

    A new study using data from NASA’s Chandra X-ray Observatory and Hubble Space Telescope gives new insight into an important question: how habitable are planets that orbit the most common type of stars in the Galaxy? The target of the new study, as reported in our press release, is Barnard’s Star, which is one of the closest stars to Earth at a distance of just 6 light years. Barnard’s Star is a red dwarf, a small star that slowly burns through its fuel supply and can last much longer than medium-sized stars like our Sun. It is about 10 billion years old, making it twice the age of the Sun.

    The authors used Barnard’s Star as a case study to learn how flares from an old red dwarf might affect any planets orbiting it. This artist’s illustration depicts an old red dwarf like Barnard’s Star (right) and an orbiting, rocky planet (left).

    The research team’s Chandra observations of Barnard’s Star taken in June 2019 uncovered one X-ray flare (shown in the inset box) and their Hubble observations taken in March 2019 revealed two ultraviolet high-energy flares (shown in an additional graphic). Both observations were about seven hours long and both plots show X-ray or ultraviolet brightness extending down to zero. Based on the length of the flares and of the observations, the authors concluded that Barnard’s Star unleashes potentially destructive flares about 25% of the time.

    2
    Credit: X-ray light curve: NASA/CXC/University of Colorado/K. France et al.; UV light curve: NASA/STScI.

    The team then studied what these results mean for rocky planets orbiting in the habitable zone — where liquid water could exist on their surface — around an old red dwarf like Barnard’s Star. Any atmosphere formed early in the life of a habitable-zone planet was likely to have been eroded away by high-energy radiation from the star during its volatile youth. Later on, however, planet atmospheres might regenerate as the star becomes less active with age. This regeneration process may occur by gases released by impacts of solid material or gases being released by volcanic processes.

    However, the onslaught of powerful flares like those reported here, repeatedly occurring over hundreds of millions of years, may erode any regenerated atmospheres on rocky planets in the habitable zone. The illustration shows the atmosphere of the rocky planet being swept away to the left by energetic radiation from flares produced by the red dwarf. This would reduce the chance of these worlds supporting life. The team is currently studying high-energy radiation from many more red dwarfs to determine whether Barnard’s Star is typical.

    A paper describing these results, led by Kevin France of the University of Colorado at Boulder, appears in the October 30, 2020 issue of The Astronomical Journal .


    A Quick Look: Assessing The Habitability of Planets Around Old Red Dwarfs

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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 12:11 pm on October 22, 2020 Permalink | Reply
    Tags: , , , , NASA Chandra, The intriguing system known as 4U 1916-053 contains two stars in a remarkably close orbit   

    From NASA Chandra: “Einstein’s Theory of Relativity, Critical for GPS, Seen in Distant Stars” 

    NASA Chandra Banner

    NASA/Chandra Telescope


    From NASA Chandra

    October 22, 2020

    1

    An effect predicted by Albert Einstein has been identified in a double star system about 29,000 light years from Earth.

    This phenomenon, called a ‘gravitational redshift,’ has been well documented in our Solar System, but it’s been more elusive farther away.

    Scientists saw evidence for this effect in the X-rays from a system with a neutron star in close orbit with a companion star.

    Gravitational redshifts are crucial for maintaining the accuracy of technologies like the global positioning system (GPS).

    What do Albert Einstein, the Global Positioning System (GPS), and a pair of stars 200,000 trillion miles from Earth have in common?

    The answer is an effect from Einstein’s General Theory of Relativity called the “gravitational redshift,” where light is shifted to redder colors because of gravity. Using NASA’s Chandra X-ray Observatory, astronomers have discovered the phenomenon in two stars orbiting each other in our galaxy about 29,000 light years (200,000 trillion miles) away from Earth. While these stars are very distant, gravitational redshifts have tangible impacts on modern life, as scientists and engineers must take them into account to enable accurate positions for GPS.

    While scientists have found incontrovertible evidence of gravitational redshifts in our solar system, it has been challenging to observe them in more distant objects across space. The new Chandra results provide convincing evidence for gravitational redshift effects at play in a new cosmic setting.

    The intriguing system known as 4U 1916-053 contains two stars in a remarkably close orbit. One is the core of a star that has had its outer layers stripped away, leaving a star that is much denser than the Sun. The other is a neutron star, an even denser object created when a massive star collapses in a supernova explosion. The neutron star (grey) is shown in this artist’s impression at the center of a disk of hot gas pulled away from its companion (white star on left).

    These two compact stars are only about 215,000 miles apart, roughly the distance between the Earth and the Moon. While the Moon orbits our planet once a month, the dense companion star in 4U 1916-053 whips around the neutron star and completes a full orbit in only 50 minutes.

    In the new work on 4U 1916-053, the team analyzed X-ray spectra — that is, the amounts of X-rays at different wavelengths — from Chandra. They found the characteristic signature of the absorption of X-ray light by iron and silicon in the spectra. In three separate observations with Chandra, the data show a sharp drop in the detected amount of X-rays close to the wavelengths where the iron or silicon atoms are expected to absorb the X-rays. One of the spectra showing absorption by iron – the dips on the left and right – is included in the main graphic. An additional graphic shows a spectrum with absorption by silicon. In both spectra the data are shown in grey and a computer model in red.

    2
    Credit: NASA/CXC/University of Michigan/N. Trueba et al.

    However, the wavelengths of these characteristic signatures of iron and silicon were shifted to longer, or redder wavelengths compared to the laboratory values found here on Earth (shown with the blue, vertical line for each absorption signature). The researchers found that the shift of the absorption features was the same in each of the three Chandra observations, and that it was too large to be explained by motion away from us. Instead they concluded it was caused by gravitational redshift.

    How does this connect with General Relativity and GPS? As predicted by Einstein’s theory, clocks under the force of gravity run at a slower rate than clocks viewed from a distant region experiencing weaker gravity. This means that clocks on Earth observed from orbiting satellites run at a slower rate. To have the high precision needed for GPS, this effect needs to be taken into account or there will be small differences in time that would add up quickly, calculating inaccurate positions.

    All types of light, including X-rays, are also affected by gravity. An analogy is that of a person running up an escalator that is going down. As they do this, the person loses more energy than if the escalator was stationary or going up. The force of gravity has a similar effect on light, where a loss in energy gives a lower frequency. Because light in a vacuum always travels at the same speed, the loss of energy and lower frequency means that the light, including the signatures of iron and silicon, shift to longer wavelengths.

    This is the first strong evidence for absorption signatures being shifted to longer wavelengths by gravity in a pair of stars that has either a neutron star or black hole. Strong evidence for gravitational redshifts in absorption has previously been observed from the surface of white dwarfs, with wavelength shifts typically only about 15% of that for 4U 1916-053.

    Scientists say it is likely that a gaseous atmosphere blanketing the disk near the neutron star (shown in blue) absorbed the X-rays, producing these results. (This atmosphere is unrelated to the bulge of red gas in the outer part of the disk that blocks light from the inner part of the disk once per orbit.) The size of the shift in the spectra allowed the team to calculate how far this atmosphere is away from the neutron star, using General Relativity and assuming a standard mass for the neutron star. They found that the atmosphere is located 1,500 miles from the neutron star, about half the distance from Los Angeles to New York and equivalent to only 0.7% of the distance from the neutron star to the companion. It likely extends over several hundred miles from the neutron star.

    In two of the three spectra there is also evidence for absorption signatures that have been shifted to even redder wavelengths, corresponding to a distance of only 0.04% of the distance from the neutron star to the companion. However, these signatures are detected with less confidence than the ones further away from the neutron star.

    Scientists have been awarded further Chandra observation time in the upcoming year to study this system in more detail.

    A paper describing these results was published in the August 10th, 2020 issue of The Astrophysical Journal Letters. The authors of the paper are Nicolas Trueba and Jon Miller (University of Michigan, Ann Arbor), Andrew Fabian (University of Cambridge, UK), J. Kaastra (Netherlands Institute for Space Research (NL)), T. Kallman (NASA Goddard Space Flight Center in Greenbelt, Maryland), A. Lohfink (Montana State University), D. Proga (University of Nevada, Las Vegas), John Raymond (Center for Astrophysics | Harvard & Smithsonian), Christopher Reynolds (University of Cambridge (UK)), and M. Reynolds and A. Zoghbi (University of Michigan).


    A Quick Look: Einstein’s Theory of Relativity, Critical for GPS, Seen in Distant Stars.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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.

     
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