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  • richardmitnick 8:12 pm on January 6, 2017 Permalink | Reply
    Tags: , , , Chandra, Chandra Deep Field South : Deepest X-ray Image Ever Reveals Black Hole Treasure Trove, ,   

    From Chandra- “Chandra Deep Field South : Deepest X-ray Image Ever Reveals Black Hole Treasure Trove” 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    January 5, 2017

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    Credit X-ray: NASA/CXC/Penn State/B.Luo et al.
    Release Date January 5, 2017
    Luo, B. et al, 2016, ApJS (in press); arXiv:1611.03501; Vito, F. et al, 2016, MNRAS, 463, 348; arXiv:1608.02614

    This image contains the highest concentration of black holes ever seen, equivalent to 5,000 over the area of the full Moon.

    Made with over 7 million seconds of Chandra observing time, this is the deepest X-ray image ever obtained.

    These data give astronomers the best look yet at the growth of black holes over billions of years soon after the Big Bang.

    This is the deepest X-ray image ever obtained, made with over 7 million seconds of observing time with NASA’s Chandra X-ray Observatory. These data give astronomers the best look yet at the growth of black holes over billions of years beginning soon after the Big Bang, as described in our latest press release.

    The image is from the Chandra Deep Field-South, or CDF-S. The full CDF-S field covers an approximately circular region on the sky with an area about two-thirds that of the full Moon. However, the outer regions of the image, where the sensitivity to X-ray emission is lower, are not shown here. The colors in this image represent different levels of X-ray energy detected by Chandra. Here the lowest-energy X-rays are red, the medium band is green, and the highest-energy X-rays observed by Chandra are blue.

    The central region of this image contains the highest concentration of supermassive black holes ever seen, equivalent to about 5,000 objects that would fit into the area of the full Moon and about a billion over the entire sky.

    Researchers used the CDF-S data in combination with data from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) and the Great Observatories Origins Deep Survey (GOODS), both including data from NASA’s Hubble Space Telescope to study galaxies and black holes between one and two billion years after the Big Bang.

    CANDELS Cosmic Assembly Near Infrared Deep Extragalactic Legacy Survey
    CANDELS Cosmic Assembly Near Infrared Deep Extragalactic Legacy Survey

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    GOODS

    In one part of the study, the team looked at the X-ray emission from galaxies detected in the Hubble images, at distances between 11.9 and 12.9 billion light years from Earth. About 50 of these distant galaxies were individually detected with Chandra. The team then used a technique called X-ray stacking to investigate X-ray emission from the 2,076 distant galaxies that were not individually detected. They added up all the X-ray counts near the positions of these galaxies, enabling much greater sensitivity to be obtained. Through stacking the team were able to achieve equivalent exposure times up to about 8 billion seconds, equivalent to about 260 years.

    Using these data, the team found evidence that black holes in the early Universe grow mostly in bursts, rather than via the slow accumulation of matter. The team may have also found hints about the types of seeds that form supermassive black holes. If supermassive black holes are born as “light” seeds weighing about 100 times the Sun’s mass, the growth rate required to reach a mass of about a billion times the Sun in the early Universe may be so high that it challenges current models for such growth. If supermassive black holes are born with more mass, the required growth rate is not as high. The data in the CDF-S suggest that the seeds for supermassive black holes may be “heavy” with masses about 10,000 to 100,000 times that of the Sun.

    Such deep X-ray data like those in the CDF-S provide useful insights for understanding the physical properties of the first supermassive black holes. The relative number of luminous and faint objects — in what astronomers call the shape of the “luminosity function” — depends on the mixture of the several physical quantities involved in black hole growth, including the mass of the black hole seeds and the rate at which they are pulling in material. The CDF-S data show a rather “flat” luminosity function (i.e., a relative large number of bright objects) that can be used to infer possible combinations of these physical quantities. However, definitive results can only come from further observations.

    The paper on black hole growth in the early Universe was led by Fabio Vito of Pennsylvania State University in University Park, Penn and was published in an August 10th, 2016 issue of the Monthly Notices of the Royal Astronomical Society. It is available online ( https://arxiv.org/abs/1608.02614 ) The survey paper was led by Bin Luo, also of Penn State and was recently accepted for publication in The Astrophysical Journal Supplement Series. It is also available online ( https://arxiv.org/abs/1611.03501 ).

    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 9:48 am on November 6, 2016 Permalink | Reply
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    From CfA: “Pulsar Wind Nebulae” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    November 4, 2016

    Neutron stars are the detritus of supernova explosions, with masses between one and several suns and diameters only tens of kilometers across. A pulsar is a spinning neutron star with a strong magnetic field; charged particles in the field radiate in a lighthouse-like beam that can sweep past the Earth with extreme regularity every few seconds or less. A pulsar also has a wind, and charged particles, sometimes accelerated to near the speed of light, form a nebula around the pulsar: a pulsar wind nebula. The particles’ high energies make them strong X-ray emitters, and the nebulae can be seen and studied with X-ray observatories. The most famous example of a pulsar wind nebula is the beautiful and dramatic Crab Nebula.

    Supernova remnant Crab nebula. NASA/ESA Hubble
    Supernova remnant Crab nebula. NASA/ESA Hubble

    When a pulsar moves through the interstellar medium, the nebula can develop a bow-shaped shock. Most of the wind particles are confined to a direction opposite to that of the pulsar’s motion and form a tail of nebulosity. Recent X-ray and radio observations of fast-moving pulsars confirm the existence of the bright, extended tails as well as compact nebulosity near the pulsars. The length of an X-ray tail can significantly exceed the size of the compact nebula, extending several light-years or more behind the pulsar.

    CfA astronomer Patrick Slane was a member of a team that used the Chandra X-ray Observatory to study the nebula around the pulsar PSR B0355+54, located about 3400 light-years away.

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    The pulsar’s observed movement over the sky (its proper motion) is measured to be about sixty kilometer per second. Earlier observations by Chandra had determined that the pulsar’s nebula had a long tail, extending over at least seven light-years (it might be somewhat longer, but the field of the detector was limited to this size); it also has a bright compact core. The scientists used deep Chandra observations to examine the nebula’s faint emission structures, and found that the shape of the nebula, when compared to the direction of the pulsar’s motion through the medium, suggests that the spin axis of the pulsar is pointed nearly directly towards us. They also estimate many of the basic parameters of the nebula including the strength of its magnetic field, which is lower than expected (or else turbulence is re-accelerating the particles and modifying the field). Other conclusions include properties of the compact core and details of the physical mechanisms powering the X-ray and radio radiation.
    Reference(s):

    Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54</emKlingler, Noel; Rangelov, Blagoy; Kargaltsev, Oleg; Pavlov, George G.; Romani, Roger W.; Posselt, Bettina; Slane, Patrick; Temim, Tea; Ng, C.-Y.; Bucciantini, Niccolò; Bykov, Andrei; Swartz, Douglas A.; Buehler, Rolf, ApJ 2016 (in press).

    See the full article here .

    Please help promote STEM in your local schools.

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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 9:48 pm on August 21, 2013 Permalink | Reply
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    From NASA Chandra: “M101: A Pinwheel in Many Colors” 

    NASA Chandra

    A new composite of M101 (aka, the “Pinwheel Galaxy”) contains data from four of NASA’s telescopes in space. X-rays from Chandra (purple) show the hottest and most energetic areas of this spiral galaxy. Infrared data from Spitzer (red) and optical emission from Hubble (yellow) trace the dust and starlight respectively. Ultraviolet light from GALEX (blue) shows the output from young stars.

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    Credit X-ray: NASA/CXC/SAO; IR & UV: NASA/JPL-Caltech; Optical: NASA/STScI
    Release Date May 24, 2012

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    The Electromagnetic Spectrum. Wavelengths and energies from gamma rays to radio.

    This image of the Pinwheel Galaxy, or also known as M101, combines data in the infrared, visible, ultraviolet and X-rays from four of NASA’s space-based telescopes. This multi-spectral view shows that both young and old stars are evenly distributed along M101’s tightly-wound spiral arms. Such composite images allow astronomers to see how features in one part of the spectrum match up with those seen in other parts. It is like seeing with a regular camera, an ultraviolet camera, night-vision goggles and X-ray vision, all at the same time.

    The Pinwheel Galaxy is in the constellation of Ursa Major (also known as the Big Dipper). It is about 70% larger than our own Milky Way Galaxy, with a diameter of about 170,000 light years, and sits at a distance of 21 million light years from Earth. This means that the light we’re seeing in this image left the Pinwheel Galaxy about 21 million years ago – many millions of years before humans ever walked the Earth.

    The hottest and most energetic areas in this composite image are shown in purple, where the Chandra X-ray Observatory observed the X-ray emission from exploded stars, million-degree gas, and material colliding around black holes.”

    See the full article here.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 3:21 pm on August 20, 2013 Permalink | Reply
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    From NASA Chandra- “Henize 2-10: A Surprisingly Close Look at the Early Cosmos” 

    NASA Chandra

    New data from Chandra and the Very Large Array suggest that black hole growth may precede the growth of bulges in some galaxies. Henize 2-10 is a dwarf starburst galaxy about 30 million light years from Earth with properties similar to those in the early Universe. X-ray and radio data indicate a black hole at the center of Henize 2-10 with a mass about one million times that of the Sun.

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    Credit X-ray (NASA/CXC/Virginia/A.Reines et al); Radio (NRAO/AUI/NSF); Optical (NASA/STScI)
    Release Date January 10, 2011

    The combined observations from multiple telescopes of Henize 2-10, a dwarf starburst galaxy located about 30 million light years from Earth, has provided astronomers with a detailed new look at how galaxy and black hole formation may have occured in the early Universe. This image shows optical data from the Hubble Space Telescope in red, green and blue, X-ray data from NASA’s Chandra X-ray Observatory in purple, and radio data from the National Radio Astronomy Observatory’s Very Large Array in yellow. A compact X-ray source at the center of the galaxy coincides with a radio source, giving evidence for an actively growing supermassive black hole with a mass of about one million times that of the Sun (please roll your mouse over the image for the location of the black hole).

    Stars are forming in Henize 2-10 at a prodigious rate, giving the star clusters in this galaxy their blue appearance. This combination of a burst of star formation and a massive black hole is analogous to conditions in the early Universe. Since Henize 2-10 does not contain a significant bulge of stars in its center, these results show that supermassive black hole growth may precede the growth of bulges in galaxies. This differs from the relatively nearby Universe where the growth of galaxy bulges and supermassive black holes appears to occur in parallel.

    A paper describing these results was published online in Nature on January 9th, 2011 by Amy Reines and Gregory Sivakoff of the University of Virginia, Kelsey Johnson of the University of Virginia and the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia and Crystal Brogan also of NRAO in Virgina.

    SAee the full article here.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 12:13 pm on August 14, 2013 Permalink | Reply
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    From NASA Chandra- “NGC 1232: Dwarf Galaxy Caught Ramming Into a Large Spiral” 

    NASA Chandra

    Observations with Chandra have revealed a giant cloud of superheated gas in a galaxy about 60 million light years from Earth. Because this gas is about 6 million degrees, it only glows in X-ray light. A collision between a dwarf galaxy and a much larger galaxy called NGC 1232 is the likely cause of this gas cloud.A new composite of X-rays (purple) from Chandra and optical data (blue and white) shows the scene of the collision.

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    Credit X-ray: NASA/CXC/Huntingdon Inst. for X-ray Astronomy/G.Garmire, Optical: ESO/VLT
    Release Date August 14, 2013

    Observations with NASA’s Chandra X-ray Observatory have revealed a massive cloud of multimillion-degree gas in a galaxy about 60 million light years from Earth. The hot gas cloud is likely caused by a collision between a dwarf galaxy and a much larger galaxy called NGC 1232. If confirmed, this discovery would mark the first time such a collision has been detected only in X-rays, and could have implications for understanding how galaxies grow through similar collisions.

    An image combining X-rays and optical light shows the scene of this collision. The impact between the dwarf galaxy and the spiral galaxy caused a shock wave – akin to a sonic boom on Earth – that generated hot gas with a temperature of about 6 million degrees. Chandra X-ray data, in purple, show the hot gas has a comet-like appearance, caused by the motion of the dwarf galaxy. Optical data from the European Southern Observatory’s Very Large Telescope reveal the spiral galaxy in blue and white. X-ray point sources have been removed from this image to emphasize the diffuse emission.

    Near the head of the comet-shaped X-ray emission is a region containing several very optically bright stars and enhanced X-ray emission. Star formation may have been triggered by the shock wave, producing bright, massive stars. In that case X-ray emission would be generated by massive star winds and by the remains of supernova explosions as massive stars evolve.

    The mass of the entire gas cloud is uncertain because it cannot be determined from the two-dimensional image whether the hot gas is concentrated in a thin pancake or distributed over a large, spherical region. If the gas is a pancake, the mass is equivalent to forty thousand Suns. If it is spread out uniformly, the mass could be much larger, about three million times as massive as the Sun. This range agrees with values for dwarf galaxies in the Local Group containing the Milky Way.

    The hot gas should continue to glow in X-rays for tens to hundreds of millions of years, depending on the geometry of the collision. The collision itself should last for about 50 million years. Therefore, searching for large regions of hot gas in galaxies might be a way to estimate the frequency of collisions with dwarf galaxies and to understand how important such events are to galaxy growth.

    An alternative explanation of the X-ray emission is that the hot gas cloud could have been produced by supernovas and hot winds from large numbers of massive stars, all located on one side of the galaxy. The lack of evidence of expected radio, infrared, or optical features argues against this possibility.

    A paper by Gordon Garmire of the Huntingdon Institute for X-ray Astronomy in Huntingdon, PA describing these results is available online and was published in the June 10th, 2013 issue of The Astrophysical Journal.”

    See the full article here, with more images and data.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 7:21 pm on August 5, 2013 Permalink | Reply
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    From NASA Chandra- “Sagittarius A* and J144701-5919: Peering Into The Heart of Darkness” 

    NASA Chandra

    The supermassive black hole at the center of the Milky Way is known as Sagittarius A* (or Sgr A*, for short). Astronomers have known for a long time that Sgr A* is relatively quiet compared to other black holes of similar size. A new theoretical model based on a very long Chandra observation of the region may explain the feeble consumption by Sgr A*. The deep Chandra image also reveals other interesting features of this region including supernova remnants and mysterious filaments.

    sgr a
    Credit NASA/CXC/MIT/F.K. Baganoff et al.
    Release Date January 5, 2010

    Astronomers have long known that the supermassive black hole at the center of the Milky Way Galaxy, known as Sagittarius A* (or Sgr A* for short), is a particularly poor eater. The fuel for this black hole comes from powerful winds blown off dozens of massive young stars that are concentrated nearby. These stars are located a relatively large distance away from Sgr A*, where the gravity of the black hole is weak, and so their high-velocity winds are difficult for the black hole to capture and swallow. Scientists have previously calculated that Sgr A* should consume only about 1% of the fuel carried in the winds.

    However, it now appears that Sgr A* consumes even less than expected – ingesting only about one percent of that one percent. Why does it consume so little? The answer may be found in a new theoretical model developed using data from a very deep exposure made by NASA’s Chandra X-ray Observatory. This model considers the flow of energy between two regions around the black hole: an inner region that is close to the so-called event horizon (the boundary beyond which even light cannot escape), and an outer region that includes the black hole’s fuel source – the young stars – extending up to a million times farther out. Collisions between particles in the hot inner region transfer energy to particles in the cooler outer region via a process called conduction. This, in turn, provides additional outward pressure that makes nearly all of the gas in the outer region flow away from the black hole. The model appears to explain well the extended shape of hot gas detected around Sgr A* in X-rays as well as features seen in other wavelengths.

    This Chandra image of Sgr A* and the surrounding region is based on data from a series of observations lasting a total of about one million seconds, or almost two weeks. Such a deep observation has given scientists an unprecedented view of the supernova remnant near Sgr A* – known as Sgr A East – and the lobes of hot gas extending for a dozen light years on either side of the black hole. These lobes provide evidence for powerful eruptions occurring several times over the last ten thousand years.

    The image also contains several mysterious X-ray filaments, some of which may be huge magnetic structures interacting with streams of energetic electrons produced by rapidly spinning neutron stars. Such features are known as pulsar wind nebulas.

    The new model of Sgr A* was presented at the 215th meeting of the American Astronomical Society in January 2010 by Roman Shcherbakov and Robert Penna of Harvard University and Frederick K. Baganoff of the Massachusetts Institute of Technology.

    See the full article here.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 6:20 pm on August 5, 2013 Permalink | Reply
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    From NASA Chandra- “NGC 7793: Black Hole Blows Big Bubble” 

    NASA Chandra

    A microquasar has been discovered in the nearby galaxy NGC 7793. In these systems, a stellar-mass black hole is being fed by a companion star. The black hole in the microquasar is generating two powerful jets, which are blowing outward and creating huge bubbles of hot gas. Microquasars are miniature versions of powerful quasars in distant galaxies and therefore useful to study.

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    Credit X-ray (NASA/CXC/Univ of Strasbourg/M. Pakull et al); Optical (ESO/VLT/Univ of Strasbourg/M. Pakull et al); H-alpha (NOAO/AURA/NSF/CTIO 1.5m)
    Release Date July 07, 2010

    This composite image shows a powerful microquasar containing a black hole in the outskirts of the nearby (12.7 million light years) galaxy NGC 7793. The large image contains data from the Chandra X-ray Observatory in red, green and blue, optical data from the Very Large Telescope in light blue, and optical emission by hydrogen (“H-alpha”) from the CTIO 1.5-m telescope in gold.

    The upper inset shows a close-up of the X-ray image of the microquasar, which is a system containing a stellar-mass black hole being fed by a companion star. Gas swirling toward the black hole forms a disk around the black hole. Twisted magnetic fields in the disk generate strong electromagnetic forces that propel some of the gas away from the disk at high speeds in two jets, creating a huge bubble of hot gas about 1,000 light years across. The faint green/blue source near the middle of the upper inset image corresponds to the position of the black hole, while the red/yellow (upper right) and yellow (lower left) sources correspond to spots where the jets are plowing into surrounding gas and heating it. The nebula produced by energy from the jets is clearly seen in the H-alpha image shown in the lower inset.

    A paper describing this work [was] published in the July 8th, 2010, issue of Nature. The authors are Manfred Pakull from the University of Strasbourg in France, Roberto Soria from University College London, and Christian Motch, also from the University of Strasbourg.”

    See the full article here.

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    NG7793, another view, this one from Spitzer

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 9:15 pm on August 2, 2013 Permalink | Reply
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    From NASA Chandra: “NGC 6872: Galaxy Collision Switches on Black Hole” 

    NASA Chandra

    NGC 6872 and IC 4970 are two galaxies in the process of merging. IC 4970 is the small galaxy at the top of the image that, thanks to Chandra and Spitzer data, is shown to contain an active supermassive black hole. It was puzzling where IC 4970 got its fuel supply since observations reveal a lack of material surrounding the black hole. The new results show IC 4970 has stripped cold gas from NGC 6872 and is using it to feed its growing black hole.

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    Credit X-ray: NASA/CXC/SAO/M.Machacek; Optical: ESO/VLT; Infrared: NASA/JPL/Caltech
    Release Date December 10, 2009
    Distance Estimate About 180 million light years

    This composite image of data from three different telescopes shows an ongoing collision between two galaxies, NGC 6872 and IC 4970 . X-ray data from NASA’s Chandra X-ray Observatory is shown in purple, while Spitzer Space Telescope’s infrared data is red and optical data from ESO’s Very Large Telescope (VLT) is colored red, green and blue.

    Astronomers think that supermassive black holes exist at the center of most galaxies. Not only do the galaxies and black holes seem to co-exist, they are apparently inextricably linked in their evolution. To better understand this symbiotic relationship, scientists have turned to rapidly growing black holes – so-called active galactic nucleus (AGN) – to study how they are affected by their galactic environments.

    The latest data from Chandra and Spitzer show that IC 4970, the small galaxy at the top of the image, contains an AGN, but one that is heavily cocooned in gas and dust. This means in optical light telescopes, like the VLT, there is little to see. X-rays and infrared light , however, can penetrate this veil of material and reveal the light show that is generated as material heats up before falling onto the black hole (seen as a bright point-like source).

    Despite this obscuring gas and dust around IC 4970, the Chandra data suggest that there is not enough hot gas in IC 4970 to fuel the growth of the AGN. Where, then, does the food supply for this black hole come from? The answer lies with its partner galaxy, NGC 6872. These two galaxies are in the process of undergoing a collision, and the gravitational attraction from IC 4970 has likely pulled over some of NGC 6872’s deep reservoir of cold gas (seen prominently in the Spitzer data), providing a new fuel supply to power the giant black hole.”

    See the full article here.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 2:54 pm on August 2, 2013 Permalink | Reply
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    From NASA Chandra: “History of X-Ray Astronomy” 

    NASA Chandra

    How do X-ray telescopes differ from optical telescopes?

    X-rays do not reflect off mirrors the same way that visible light does. Because of their high-energy, X-ray photons penetrate into the mirror in much the same way that bullets slam into a wall. Likewise, just as bullets ricochet when they hit a wall at a grazing angle, so too will X-rays ricochet off mirrors (see diagram below). These properties mean that X-ray telescopes must be very different from optical telescopes. The mirrors have to be precisely shaped and aligned nearly parallel to incoming X-rays. Thus they look more like barrels than the familiar dish shape of optical telescopes.

    The first imaging X-ray telescope was made by a team of scientists under the direction of Riccardo Giacconi at American Science and Engineering in Cambridge, MA. It was flown on a small sounding rocket in 1963 and made crude images of hot spots in the upper atmosphere of the Sun.

    This telescope was about the same diameter and length as the optical telescope Galileo used in 1610. Over a period of 380 years, optical telescopes improved in sensitivity by 100 million times from Galileo’s telescope to the Hubble Space Telescope. Remarkably, Chandra represents a leap of 100 million in sensitivity, yet it took only 36 years to achieve!

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    Why are X-ray observatories in space?

    The building and operation of an X-ray observatory is a marvel of modern technology and ingenuity. Engineers, technicians and scientists design and build large, curving mirrors that can be nested inside one another to increase the total reflecting area of the telescope. The mirrors focus X-ray photons onto state-of-the-art detectors which record the direction and in some cases, the energy of the photons.

    Because the Earth’s atmosphere absorbs X-rays, X-ray observatories must be placed high above the Earth’s surface. This means that the ultra-precise mirrors and detectors, together with the sophisticated electronics that conveys the information back to Earth must be able to withstand the rigors of a rocket launch, and operate in the hostile environment of space.

    X-Ray Instruments Detect Neutron Stars and Black Holes

    The first hint that cosmic X-rays exist came in 1949, when radiation detectors aboard rockets were briefly carried above the atmosphere where they detected X-rays coming from the Sun. It took more than a decade before a greatly improved detector discovered X-rays coming from sources beyond the solar system.

    The most important X-ray astronomy mission of the present decade is NASA’s Chandra X-ray Observatory, which was launched on July 23, 1999. This telescope contains four sets of nested mirrors and is the premier X-ray observatory to date. It can detect sources more than twice as far away and produce images with five times greater detail. The mirrors have been polished to a smoothness of a few atoms. If the surface of the Earth were as smooth as the Chandra mirrors, the largest mountain would be less than 2 meters (7 feet) tall!
    View the schematic image
    Watch the animation

    X-ray telescopes have a different design from optical telescopes because X-rays will reflect off mirrors only if they strike them at grazing angles. Two reflections are used to focus the X-rays to a point.

    The area of an X-ray telescope can be increased by nesting the mirrors inside one another.”

    See the full article here.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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  • richardmitnick 4:06 pm on July 30, 2013 Permalink | Reply
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    From NASA Chandra: “Chemistry and the Universe” 

    NASA Chandra

    “Chemistry, the study of the intricate dances and bondings of low-energy electrons to form the molecules that make up the world we live in, may seem far removed from the thermonuclear heat in the interiors of stars and the awesome power of supernovas. Yet, there is a fundamental connection between them.

    To illustrate this connection, the familiar periodic table of elements—found in virtually every chemistry class—has been adapted to show how astronomers see the chemical Universe. What leaps out of this table is that the simplest elements, hydrogen and helium, are far and away the most abundant.

    PeriodicTable2

    The Universe started out with baryonic matter in its simplest form, hydrogen. In just the first 20 minutes or so after the Big Bang, about 25% of the hydrogen was converted to helium. In essence, the chemical history of the Universe can be divided into two mainphases: one lasting 20 minutes, and the rest lasting for 13.7 billion years and counting.

    After that initial one third of an hour, the expanding Universe cooled below the point where nuclear fusion could operate. This meant that no evolution of matter could occur again until stars were formed a few million years later. Then the buildup of elements heavier than helium could begin.

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    The chemical composition of the Universe has been constantly changing throughout its 13.7 billion year history. Illustration: NASA/CXC/M.Weiss

    Stars evolve through a sequence of stages in which nuclear fusion reactions in their central regions build up helium and other elements .The energy supplied by fusion reactions creates the pressure needed to hold the star up against gravity. Winds of gas escaping from stars distribute some of this processed matter into space in a relatively gentle manner and supernovas do it violently. See the below image.

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    As the enrichment of the interstellar and intergalactic gas has proceeded over vast stretches of space and time, the chemistry of the cosmos has become richer, too. Subsequent generations of stars have formed from interstellar gas enriched in heavy elements. Our Sun, Solar System, and indeed the existence of life on Earth are direct results of this long chain of stellar birth, death, and rebirth. In this way, the evolution of matter, stars and galaxies are all inextricably tied together and so too are astronomy and chemistry.”

    See the full article here.

    Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory


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