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Sample records for varadan jagdish chandra

  1. Ahluwalia, Prof. Jagdish Chander

    Indian Academy of Sciences (India)

    Ahluwalia, Prof. Jagdish Chander Ph.D. (Purdue), FNA. Date of birth: 6 July 1935. Specialization: Thermodynamics of Biopolymers & Surfactants in Solutions and Solute-Solvent Interactions Address: 186, SFS Apartments, Hauz Khas, New Delhi 110 016, U.T.. Contact: Residence: (011) 2656 4519. Mobile: 92137 36359

  2. Chandra's X-ray Vision

    Indian Academy of Sciences (India)

    1999-07-23

    Jul 23, 1999 ... GENERAL I ARTICLE. Chandra's X-ray Vision. K P Singh. Chandra X-ray Observatory (CXO) is a scientific satellite (moon/ chandra), named after the Indian-born Nobel laureate. Subrahmanyan Chandrasekhar - one of the foremost astro- physicists of the twentieth century and popularly known as. Chandra.

  3. Karthik Raman Nagasuma Chandra

    Indian Academy of Sciences (India)

    Author Affiliations. Karthik Raman1 Nagasuma Chandra2. Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland; Bioinformatics Centre, Raman building, Indian Institute of Science, Bangalore 560 012, India ...

  4. Mishra, Dr Gyan Chandra

    Indian Academy of Sciences (India)

    Fellow Profile. Elected: 2005 Section: General Biology. Mishra, Dr Gyan Chandra Ph.D. (Udaipur), FNASc, FNA. Date of birth: 15 August 1947. Specialization: Immunology and Cell Biology Address: NASI Senior Scientist, National Centre for Cell Science, NCCS Complex, Ganeshkhind, Pune 411 007, Maharashtra Contact:

  5. Khanna, Dr Navin Chandra

    Indian Academy of Sciences (India)

    Elected: 2017 Section: Medicine. Khanna, Dr Navin Chandra Ph.D. (AIIMS), FNASc. Date of birth: 1 April 1956. Specialization: Dengue Subunit Vaccine, Dengue Botanical Drug, Recombinant Proteins of Medical Use Address: International Centre for Genetic Engineering, and Biotechnology, Aruna Asaf Ali Marg, New Delhi ...

  6. Mandal, Prof. Nitai Chandra

    Indian Academy of Sciences (India)

    Nitai Chandra Ph.D. (Calcutta), FNA, FNASc. Date of birth: 12 July 1938. Specialization: Molecular Genetics and Molecular Biology of Prokaryotes Address: E-5, Digantika, AH Block, Sector II, Salt Lake, Kolkata 700 091, W.B.. Contact: Residence: (033) 2359 1356. Mobile: 94775 85894. Email: mandalnc2003@yahoo.com.

  7. Chandra follow-up

    Science.gov (United States)

    Maccarone, Thomas J.; Bahramian, Arash; Heinke, Craig; Shaw, Aarran; Sivakoff, Greg; Kennea, Jamie; Wijnands, Rudy; Degenaar, Nathalie; Strader, Jay; in't Zand, Jean; Kuulkers, Erik; Chakrabarty, Deepto

    2017-05-01

    We observed Swift J1752339-290952 (ATel #10422) with Chandra with ACIS-S via a Director's Discretionary Time program. The data were taken starting on 2017-05-25 at 3:22:23 TT for 8 ks. Eight photons were detected, indicating that the source has faded by a factor of several hundred since the original reported detection.

  8. The First Chandra Field

    Energy Technology Data Exchange (ETDEWEB)

    Weisskopf, Martin C.; /NASA, Marshall; Aldcroft, Thomas L.; /Harvard-Smithsonian Ctr. Astrophys.; Cameron, Robert A.; /Harvard-Smithsonian Ctr. Astrophys. /SLAC; Gandhi,; Foellmi, Cedric; /European Southern Obs., Chile; Elsner, Ronald F.; /NASA, Marshall; Patel, Sandeep K.; /USRA, Huntsville; Wu, Kinwah; /Mullard Space Sci. Lab.; O' Dell, Stephen; /NASA, Marshall

    2005-09-09

    Before the official first-light images, the Chandra X-ray Observatory obtained an X-ray image of the field to which its focal plane was first exposed. We describe this historic observation and report our study of the first Chandra field. Chandra's Advanced CCD Imaging Spectrometer (ACIS) detected 15 X-ray sources, the brightest being dubbed ''Leon X-1'' to honor the Chandra Telescope Scientist, Leon Van Speybroeck. Based upon our analysis of the X-ray data and spectroscopy at the European Southern Observatory (ESO; La Silla, Chile), we find that Leon X-1 is a Type-1 (unobscured) active galactic nucleus (AGN) at a redshift z = 0.3207. Leon X-1 exhibits strong Fe II emission and a broad-line Balmer decrement that is unusually flat for an AGN. Within the context of the Eigenvector-1 correlation space, these properties suggest that Leon X-1 may be a massive ({ge} 10{sup 9} M{sub {circle_dot}}) black hole, accreting at a rate approaching its Eddington limit.

  9. Chaturvedi, Prof. Umesh Chandra

    Indian Academy of Sciences (India)

    Chaturvedi, Prof. Umesh Chandra M.D. (Lucknow), FRC Path. (London), FAMS, FNA, FNASc, FAAM(USA). Date of birth: 2 March 1939. Specialization: Medical Microbiology, Virology and Immunology Address: 201, Annapurna Apartments, No. 1, Bishop Rocky Street, Faizabad Road, Lucknow 226 007, U.P.. Contact:

  10. Thakur, Dr Vikram Chandra

    Indian Academy of Sciences (India)

    Fellow Profile. Elected: 1991 Section: Earth & Planetary Sciences. Thakur, Dr Vikram Chandra Ph.D. (London). Date of birth: 15 January 1940. Specialization: Structural Geology, Tectonics of Himalayan Geology and Active Tectonics Address: 9/12 (Lane 9), Ashirwad Eclave, Dehra Dun 248 001, Uttarakhand Contact:

  11. Budhani, Dr Ramesh Chandra

    Indian Academy of Sciences (India)

    Budhani, Dr Ramesh Chandra Ph.D. (IIT, Delhi), FNASc, FNA. Date of birth: 3 February 1955. Specialization: Renewable Energy, Nanoscale Systems, Experimental Condensed Matter Physics, Superconductivity and Magnetism Address: Department of Physics, Lasers & Photonics, Indian Institute of Technology, Kanpur 208 ...

  12. Mehta, Prof. Chandra Lal

    Indian Academy of Sciences (India)

    Elected: 1982 Section: Physics. Mehta, Prof. Chandra Lal Ph.D. (Rochester). Date of birth: 31 July 1938. Specialization: Quantum & Statistical Optics and Mathematical Physics Address: B-43, Gyandeep Apartments, Mayur Vihar, Phase I, New Delhi 110 091, U.T.. Contact: Residence: (011) 2279 6410. Mobile: 90133 91375

  13. Nirab Chandra Adhikary

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. Nirab Chandra Adhikary. Articles written in Bulletin of Materials Science. Volume 37 Issue 7 December 2014 pp 1613-1624. Enhancement of proton conductivity of sulfonated polystyrene membrane prepared by plasma polymerization process · Bhabesh Kumar Nath Aziz Khan ...

  14. Ten Years of Chandra

    Science.gov (United States)

    Weisskopf, Martin C.

    2009-01-01

    We celebrated the 10-th anniversary of the Launch of the Chandra X-ray Observatory on July 13, 2009. During these 10 years data from this Great Observatory have had a profound impact on 21st century astrophysics. With its unrivaled capability to produce sub-arcsecond images, the Observatory has enabled astronomers to make new discoveries in topics as diverse as comets and cosmology. We shall review some of the highlights, discuss the current status, and future plans.

  15. Chandra Discovers Cosmic Cannonball

    Science.gov (United States)

    2007-11-01

    One of the fastest moving stars ever seen has been discovered with NASA's Chandra X-ray Observatory. This cosmic cannonball is challenging theories to explain its blistering speed. Astronomers used Chandra to observe a neutron star, known as RX J0822-4300, over a period of about five years. During that span, three Chandra observations clearly show the neutron star moving away from the center of the Puppis A supernova remnant. This remnant is the stellar debris field created during the same explosion in which the neutron star was created about 3700 years ago. Chandra X-ray Image of RX J0822-4300 in Puppis A Chandra X-ray Image of RX J0822-4300 in Puppis A By combining how far it has moved across the sky with its distance from Earth, astronomers determined the neutron star is moving at over 3 million miles per hour. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far. "This star is moving at 3 million miles an hour, but it's so far away that the apparent motion we see in five years is less than the height of the numerals in the date on a penny, seen from the length of a football field," said Frank Winkler of Middlebury College in Vermont. "It's remarkable, and a real testament to the power of Chandra, that such a tiny motion can be measured." Labeled Image of RX J0822-4300 in Puppis A Labeled Image of RX J0822-4300 in Puppis A "Just after it was born, this neutron star got a one-way ticket out of the Galaxy," said co-author Robert Petre of NASA's Goddard Space Flight Center in Greenbelt, Md. "Astronomers have seen other stars being flung out of the Milky Way, but few as fast as this." So-called hypervelocity stars have been previously discovered shooting out of the Milky Way with speeds around one million miles per hour. One key difference between RX J0822-4300 and these other reported galactic escapees is the source of their speed. The hypervelocity stars are

  16. Chandra Madramootoo | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... Technology (MIT). He previously served as Dean of the Faculty of Agricultural and Environmental Sciences and as Director of the Brace Centre for Water Resources Management at McGill University. Currently, Chandra is Chair of the Board of Trustees of the International Crops Research Institute for the Semi-Arid Tropics.

  17. Patel, Prof. Chandra Kumar Naranbhai

    Indian Academy of Sciences (India)

    Elected: 1995 Section: Patel, Prof. Chandra Kumar Naranbhai. Date of birth: 2 July 1938. Address: President & CEO, Pranalytica Inc., 1101, Colorado Avenue, Santa Monica, CA 90401, U.S.A.. Contact: Office: (+1-310) 458 0808. Residence: (+1-310) 471 6505. Fax: (+1-310) 458 0171. Email: patel@pranalytica.com.

  18. YZ Cnc Chandra observing campaign

    Science.gov (United States)

    Waagen, Elizabeth O.

    2016-12-01

    Dr. Christian Knigge (University of Southampton) and colleagues have requested AAVSO coverage of the SU UMa-type dwarf nova YZ Cnc in support of Chandra X-ray observations to be carried out via a Target of Opportunity (TOO) triggering when the system is in a suitable outburst. YZ Cnc has normal outbursts about every 7-10 days, and superoutbursts about every 100-110 days. The astronomers are planning to use a superoutburst to time the trigger of the TOO observations to cover not only the superoutburst but also the following normal outburst; the superoutburst must occur at a time favorable for observing with Chandra. Once the TOO observations have been triggered, coverage will need to continue through at least one normal outburst after the Chandra observations have been completed. Good coverage of YZ Cnc from AAVSO observers this season is essential; your observations will be used to decide when to trigger the TOO observations. When the TOO observations are triggered, observers will be notified and revised observing instructions will likely be issued via an AAVSO Special Notice and/or via the discussion thread on this campaign on the AAVSO Campaigns and Observation Reports forum on the AAVSO website. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  19. Chandra Catches "Piranha" Black Holes

    Science.gov (United States)

    2007-07-01

    Supermassive black holes have been discovered to grow more rapidly in young galaxy clusters, according to new results from NASA's Chandra X-ray Observatory. These "fast-track" supermassive black holes can have a big influence on the galaxies and clusters that they live in. Using Chandra, scientists surveyed a sample of clusters and counted the fraction of galaxies with rapidly growing supermassive black holes, known as active galactic nuclei (or AGN). The data show, for the first time, that younger, more distant galaxy clusters contained far more AGN than older, nearby ones. Galaxy clusters are some of the largest structures in the Universe, consisting of many individual galaxies, a few of which contain AGN. Earlier in the history of the universe, these galaxies contained a lot more gas for star formation and black hole growth than galaxies in clusters do today. This fuel allows the young cluster black holes to grow much more rapidly than their counterparts in nearby clusters. Illustration of Active Galactic Nucleus Illustration of Active Galactic Nucleus "The black holes in these early clusters are like piranha in a very well-fed aquarium," said Jason Eastman of Ohio State University (OSU) and first author of this study. "It's not that they beat out each other for food, rather there was so much that all of the piranha were able to really thrive and grow quickly." The team used Chandra to determine the fraction of AGN in four different galaxy clusters at large distances, when the Universe was about 58% of its current age. Then they compared this value to the fraction found in more nearby clusters, those about 82% of the Universe's current age. The result was the more distant clusters contained about 20 times more AGN than the less distant sample. AGN outside clusters are also more common when the Universe is younger, but only by factors of two or three over the same age span. "It's been predicted that there would be fast-track black holes in clusters, but we never

  20. Chandra Observations of Neutron Stars -- An Overview

    OpenAIRE

    Weisskopf, M. C.

    2002-01-01

    We present a brief review of Chandra observations of neutron stars, with a concentration on neutron stars in supernova remnants. The early Chandra results clearly demonstrate how critical the angular resolution has been in order to separate the neutron star emission from the surrounding nebulosity.

  1. Chandra Observations of Hydra A

    Science.gov (United States)

    McNamara, Brian; Lavoie, Anthony R. (Technical Monitor)

    2000-01-01

    We present Chandra X-ray Observations of the Hydra A cluster of galaxies, and we report the discovery of structure in the central 80 kpc of the cluster's X-ray-emitting gas. The most remarkable structures are depressions in the X-ray surface brightness, approx. 25 - 35 kpc diameter, that are coincident with Hydra A's radio lobes. The depressions are nearly devoid of X-ray-emitting gas, and there is no evidence for shock-heated gas surrounding the radio lobes. We suggest the gas within the surface brightness depressions was displaced as the radio lobes expanded subsonically, leaving cavities in the hot atmosphere. The gas temperature declines from 4 keV at 70 kpc to 3 keV in the inner 20 kpc of the brightest cluster galaxy (BCG), and the cooling time of the gas is approx. 600 Myr in the inner 10 kpc. These properties are consistent with the presence of a approx. 34 solar mass/yr cooling flow within a 70 kpc radius. Bright X-ray emission is present in the BCG surrounding a recently-accreted disk of nebular emission and young stars. The star formation rate is commensurate with the cooling rate of the hot gas within the volume of the disk, although the sink for the material that may be cooling at larger radii remains elusive.

  2. Chandra Looks Back At The Earth

    Science.gov (United States)

    2005-12-01

    In an unusual observation, a team of scientists has scanned the northern polar region of Earth with NASA's Chandra X-ray Observatory. The results show that the aurora borealis, or "northern lights," also dance in X-ray light, creating changing bright arcs of X-ray energy above the Earth's surface. While other satellite observations had previously detected high-energy X-rays from the Earth auroras, the latest Chandra observations reveal low-energy X-rays generated during auroral activity for the first time. The researchers, led by Dr. Ron Elsner of NASA's Marshall Space Flight Center in Huntsville, Ala., used Chandra to observe the Earth 10 times over a four-month period in 2004. The images were created from approximately 20-minute scans during which Chandra was aimed at a fixed point in the sky and the Earth's motion carried the auroral regions through Chandra's field of view. From the ground, the aurora are well known to change dramatically over time and this is the case in X-ray light as well. The X-rays in this sample of the Chandra observations, which have been superimposed on a simulated image of the Earth, are seen here at four different epochs. Illlustration of Earth's Magnetosphere and Auroras Illlustration of Earth's Magnetosphere and Auroras Auroras are produced by solar storms that eject clouds of energetic charged particles. These particles are deflected when they encounter the Earth�s magnetic field, but in the process large electric voltages are created. Electrons trapped in the Earth�s magnetic field are accelerated by these voltages and spiral along the magnetic field into the polar regions. There they collide with atoms high in the atmosphere and emit X-rays. Chandra has also observed dramatic auroral activity on Jupiter. Dr. Anil Bhardwaj of Vikram Sarabhai Space Center in Trivandrum, India, is the lead author on a paper describing these results in the Journal of Atmospheric and Solar-Terrestrial Physics. Dr. Bhardwaj was a co

  3. Chemical Research of Sir Prafulla Chandra Ray

    Indian Academy of Sciences (India)

    Prafulla Chandra Ray was the pathfinder and originator of chemical research in modern India. He was introduced to re- search by Alexander Crum Brown, a notable chemist and teacher at Edinburgh University. His doctoral work was on the chemis- try of double sulphates. He received the D.Sc. degree of. Edinburgh ...

  4. Spectral analysis of the Chandra comet survey

    NARCIS (Netherlands)

    Bodewits, D.; Christian, D. J.; Torney, M.; Dryer, M.; Lisse, C. M.; Dennerl, K.; Zurbuchen, T. H.; Wolk, S. J.; Tielens, A. G. G. M.; Hoekstra, R.

    Aims. We present results of the analysis of cometary X-ray spectra with an extended version of our charge exchange emission model (Bodewits et al. 2006). We have applied this model to the sample of 8 comets thus far observed with the Chandra X-ray observatory and acis spectrometer in the 300 - 1000

  5. Chandra Catches Early Phase of Cosmic Assembly

    Science.gov (United States)

    2004-08-01

    A NASA Chandra X-ray Observatory image has revealed a complex of several intergalactic hot gas clouds in the process of merging. The superb Chandra spatial resolution made it possible to distinguish individual galaxies from the massive clouds of hot gas. One of the clouds, which that envelops hundreds of galaxies, has an extraordinarily low concentration of iron atoms, indicating that it is in the very early stages of cluster evolution. "We may be seeing hot intergalactic gas in a relatively pristine state before it has been polluted by gas from galaxies," said Q. Daniel Wang of the University of Massachusetts in Amherst, and lead author on an upcoming Astrophysical Journal article describing the study. "This discovery should provide valuable insight into how the most massive structures in the universe are assembled." 3-Panel Image of Abell 2125, Its Core & Galaxy C153 3-Panel Image of Abell 2125, Its Core & Galaxy C153 The complex, known as Abell 2125,is about 3 billion light years from Earth, and is seen at a time about 11 billion years after the Big Bang, when many galaxy clusters are believed to have formed. The Chandra Abell 2125 image shows several huge elongated clouds of multimillion degree gas coming together from different directions. These hot gas clouds, each of which contains hundreds of galaxies, appear to be in the process of merging to form a single massive galaxy cluster. Chandra, Hubble Space Telescope, and Very Large Array radio telescope data show that several galaxies in the Abell 2125 core cluster are being stripped of their gas as they fall through surrounding high-pressure hot gas. This stripping process has enriched the core cluster's gas in heavy elements such as iron. Abell 2125's Core & Galaxy C153 Abell 2125's Core & Galaxy C153 The gas in the pristine cloud, which is still several million light years away from the core cluster, is conspicuous for its lack of iron atoms. This anemic cloud must be in a very early evolutionary stage. The

  6. Chandra Telescope Designer Wins 2002 Rossi Prize

    Science.gov (United States)

    2002-01-01

    Leon Van Speybroeck of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts has been awarded the 2002 Bruno Rossi Prize of the High Energy Astrophysics Division of the American Astronomical Society. The Rossi Prize recognizes significant contributions in high-energy astrophysics. It is awarded annually in honor of the late Massachusetts Institute of Technology Professor Bruno Rossi, an authority on cosmic ray physics and a pioneer in the field of X-ray astronomy. The prize also includes an engraved certificate and a $1,500 award. Van Speybroeck, who led the effort to design and make the X-ray mirrors for NASA's premier X­ray observatory, the Chandra X-ray Observatory, was recognized for a career of stellar achievements in designing precision X-ray optics. As Telescope Scientist for Chandra, he has worked for more than 20 years with a team that includes scientists and engineers from the Harvard-Smithsonian, NASA's Marshall Space Flight Center, TRW, Inc., Hughes-Danbury (now B.F. Goodrich Aerospace), Optical Coating Laboratories, Inc., and Eastman-Kodak on all aspects of the X-ray mirror assembly that is the heart of the observatory. "Leon is one of the master mirror designers of our time," said Harvey Tananbaum, director of the Chandra X-ray Center. "His contributions were crucial to the spectacular success of the Chandra mission." The Chandra mirrors are the most precise mirrors ever made, smooth with tolerances of a few atoms. If the state of Colorado had the same relative smoothness as the surface of the Chandra X-ray Observatory mirrors, Pike's Peak would be less than an inch tall. The smoothness and alignment of the Chandra's mirrors are enabling scientists to make new discoveries about black holes, neutron stars, and galactic explosions. "Many, many other people made essential contributions to the Chandra program, and hopefully some of them will receive proper recognition," said Van Speybroeck. "In the meantime, I am thoroughly enjoying

  7. Chandra Observations of Isolated Neutron Stars

    Science.gov (United States)

    Weisskopf, Martin

    2006-01-01

    We present a review of the first six years of Chandra X-ray Observatory observations of isolated neutron stars. The outstanding spatial and spectral resolution of this great observatory have allowed for observations of unprecedented clarity and accuracy. Many of these observations have provided new insights into neutron star physics. We present a (biased) overview of six years of these observations, highlighting new discoveries made possible by the Observatory's unique capabilities.

  8. Chandra Maps Vital Elements From Supernova

    Science.gov (United States)

    1999-12-01

    A team of astronomers led by Dr. John Hughes of Rutgers University in Piscataway, NJ has used observations from NASA's orbital Chandra X-ray Observatory to make an important new discovery that sheds light on how silicon, iron, and other elements were produced in supernova explosions. An X-ray image of Cassiopeia A (Cas A), the remnant of an exploded star, reveals gaseous clumps of silicon, sulfur, and iron expelled from deep in the interior of the star. The findings appear online in the Astrophysical Journal Letters at http://www.journals.uchicago.edu/ and are slated for print publication on Jan. 10, 2000. Authors of the paper, "Nucleosynthesis and Mixing in Cassiopeia A", are Hughes, Rutgers graduate student Cara Rakowski, Dr. David Burrows of the Pennsylvania State University, University Park, PA and Dr. Patrick Slane of the Harvard-Smithsonian Center for Astrophysics, Cambridge, MA. According to Hughes, one of the most profound accomplishments of twentieth century astronomy is the realization that nearly all of the elements other than hydrogen and helium were created in the interiors of stars. "During their lives, stars are factories that take the simplest element, hydrogen, and convert it into heavier ones," he said. "After consuming all the hydrogen in their cores, stars begin to evolve rapidly, until they finally run out of fuel and begin to collapse. In stars ten times or so more massive than our Sun, the central parts of the collapsing star may form a neutron star or a black hole, while the rest of the star is blown apart in a tremendous supernova explosion." Supernovae are rare, occurring only once every 50 years or so in a galaxy like our own. "When I first looked at the Chandra image of Cas A, I was amazed by the clarity and definition," said Hughes. "The image was much sharper than any previous one and I could immediately see lots of new details." Equal in significance to the image clarity is the potential the Chandra data held for measuring the

  9. Chandra Catches Milky Way Monster Snacking

    Science.gov (United States)

    2001-09-01

    For the first time astronomers have detected material being consumed by the supermassive black hole in our own backyard. A violent, rapid X-ray flare, captured by NASA's Chandra X-ray Observatory, has been observed from the direction of the supermassive black hole that resides at the center of our Milky Way Galaxy. A team of scientists, led by Fredrick K. Baganoff of the Massachusetts Institute of Technology (MIT) in Cambridge, detected a sudden X-ray flare while observing Sagittarius A*, a source of radio emission believed to be associated with the black hole at the center of our Galaxy. "This is extremely exciting because it's the first time we have seen our own neighborhood supermassive black hole devour a chunk of material," Baganoff said. "It's as if the material there sent us a postcard before it fell in." In a few minutes, the source brightened dramatically, eventually reaching a level 45 times brighter than before the flare. After about three hours, the X-ray intensity rapidly declined to the pre-flare level. "The rapid rise and fall of the X-rays from this outburst are compelling evidence that the X-ray emission is coming from matter falling into a supermassive black hole, confirming that it is powered by the same accretion process as quasars and other active galactic nuclei," said Baganoff. Baganoff added that the data also provide the best look yet at the area just outside this event horizon, the surface of "no return" for matter or light falling into a black hole. Studies of the central region of our Milky Way Galaxy in the infrared and radio wavebands indicate the presence of a large, dark object, presumably a supermassive black hole, having the mass of about 3 million suns. The faintness of Sagittarius A* at all wavelengths, especially in X-rays, has puzzled scientists who expected that the infalling matter should shine more brightly on its way in, and this has left some room for doubt. The latest precise Chandra observations of the crowded galactic

  10. NASA's Chandra Finds Youngest Nearby Black Hole

    Science.gov (United States)

    2010-11-01

    Astronomers using NASA's Chandra X-ray Observatory have found evidence of the youngest black hole known to exist in our cosmic neighborhood. The 30-year-old black hole provides a unique opportunity to watch this type of object develop from infancy. The black hole could help scientists better understand how massive stars explode, which ones leave behind black holes or neutron stars, and the number of black holes in our galaxy and others. The 30-year-old object is a remnant of SN 1979C, a supernova in the galaxy M100 approximately 50 million light-years from Earth. Data from Chandra, NASA's Swift satellite, the European Space Agency's XMM-Newton and the German ROSAT observatory revealed a bright source of X-rays that has remained steady during observation from 1995 to 2007. This suggests the object is a black hole being fed either by material falling into it from the supernova or a binary companion. "If our interpretation is correct, this is the nearest example where the birth of a black hole has been observed," said Daniel Patnaude of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. who led the study. The scientists think SN 1979C, first discovered by an amateur astronomer in 1979, formed when a star about 20 times more massive than the Sun collapsed. Many new black holes in the distant universe previously have been detected in the form of gamma-ray bursts (GRBs). However, SN 1979C is different because it is much closer and belongs to a class of supernovas unlikely to be associated with a GRB. Theory predicts most black holes in the universe should form when the core of a star collapses and a GRB is not produced. "This may be the first time the common way of making a black hole has been observed," said co-author Abraham Loeb, also of the Harvard-Smithsonian Center for Astrophysics. "However, it is very difficult to detect this type of black hole birth because decades of X-ray observations are needed to make the case." The idea of a black hole with

  11. ASA's Chandra Neon Discovery Solves Solar Paradox

    Science.gov (United States)

    2005-07-01

    NASA's Chandra X-ray Observatory survey of nearby sun-like stars suggests there is nearly three times more neon in the sun and local universe than previously believed. If true, this would solve a critical problem with understanding how the sun works. "We use the sun to test how well we understand stars and, to some extent, the rest of the universe," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "But in order to understand the sun, we need to know exactly what it is made of," he added. It is not well known how much neon the sun contains. This is critical information for creating theoretical models of the sun. Neon atoms, along with carbon, oxygen and nitrogen, play an important role in how quickly energy flows from nuclear reactions in the sun's core to its edge, where it then radiates into space. Chandra X-ray Spectrum of II Pegasi Chandra X-ray Spectrum of II Pegasi The rate of this energy flow determines the location and size of a crucial stellar region called the convection zone. The zone extends from near the sun's surface inward approximately 125,000 miles. The zone is where the gas undergoes a rolling, convective motion much like the unstable air in a thunderstorm. "This turbulent gas has an extremely important job, because nearly all of the energy emitted at the surface of the sun is transported there by convection," Drake said. The accepted amount of neon in the sun has led to a paradox. The predicted location and size of the solar convection zone disagree with those deduced from solar oscillations. Solar oscillations is a technique astronomers previously relied on to probe the sun's interior. Several scientists have noted the problem could be fixed if the abundance of neon is in fact about three times larger than currently accepted. Attempts to measure the precise amount of neon in the Sun have been frustrated by a quirk of nature; neon atoms in the Sun give off no signatures in visible light. However, in a gas

  12. NASA's Chandra Sees Brightest Supernova Ever

    Science.gov (United States)

    2007-05-01

    WASHINGTON - The brightest stellar explosion ever recorded may be a long-sought new type of supernova, according to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes. This discovery indicates that violent explosions of extremely massive stars were relatively common in the early universe, and that a similar explosion may be ready to go off in our own galaxy. "This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before." Chandra X-ray Image of SN 2006gy Chandra X-ray Image of SN 2006gy Astronomers think many of the first generation of stars were this massive, and this new supernova may thus provide a rare glimpse of how the first stars died. It is unprecedented, however, to find such a massive star and witness its death. The discovery of the supernova, known as SN 2006gy, provides evidence that the death of such massive stars is fundamentally different from theoretical predictions. "Of all exploding stars ever observed, this was the king," said Alex Filippenko, leader of the ground-based observations at the Lick Observatory at Mt. Hamilton, Calif., and the Keck Observatory in Mauna Kea, Hawaii. "We were astonished to see how bright it got, and how long it lasted." The Chandra observation allowed the team to rule out the most likely alternative explanation for the supernova: that a white dwarf star with a mass only slightly higher than the sun exploded into a dense, hydrogen-rich environment. In that event, SN 2006gy should have been 1,000 times brighter in X-rays than what Chandra detected. Animation of SN 2006gy Animation of SN 2006gy "This provides strong evidence that SN 2006gy was, in fact, the death of an

  13. Cosmic Pressure Fronts Mapped by Chandra

    Science.gov (United States)

    2000-03-01

    A colossal cosmic "weather system" produced by the collision of two giant clusters of galaxies has been imaged by NASA's Chandra X-ray Observatory. For the first time, the pressure fronts in the system can be traced in detail, and they show a bright, but relatively cool 50 million degree Celsius central region embedded in large elongated cloud of 70 million degree Celsius gas, all of which is roiling in a faint "atmosphere"of 100 million degree Celsius gas. "We can compare this to an intergalactic cold front," said Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. and leader of the international team involved in the analysis of the observations. "A major difference is that in this case, cold means 70 million degree Celsius." The gas clouds are in the core of a galaxy cluster known as Abell 2142. The cluster is six million light years across and contains hundreds of galaxies and enough gas to make a thousand more. It is one of the most massive objects in the universe. Galaxy clusters grow to vast sizes as smaller clusters are pulled inward under the influence of gravity. They collide and merge over the course of billions of years, releasing tremendous amounts of energy that heats the cluster gas to 100 million degrees Celsius. The Chandra data provides the first detailed look at the late stages of this merger process. Previously, scientists had used the German-US Roentgensatellite to produce a broad brush picture of the cluster. The elongated shape of the bright cloud suggested that two clouds were in the process of coalescing into one, but the details remained unclear. Chandra is able to measure variations of temperature, density, and pressure with unprecedented resolution. "Now we can begin to understand the physics of these mergers, which are among the most energetic events in the universe," said Markevitch. "The pressure and density maps of the cluster show a sharp boundary that can only exist in the moving environment of a

  14. Chandra Associates Pulsar and Historic Supernova

    Science.gov (United States)

    2001-01-01

    SAN DIEGO -- Scientists using NASA’s Chandra X-ray Observatory have found new evidence that a pulsar in the constellation of Sagittarius was created when a massive star exploded, witnessed by Chinese astronomers in the year 386 AD. If confirmed, this will be only the second pulsar to be clearly associated with a historic event. These results were presented today by Victoria Kaspi and Mallory Roberts of McGill University at the American Astronomical Society meeting. Also participating in the research were Gautum Vasisht from the Jet Propulsion Laboratory, Eric Gotthelf from Columbia University, Michael Pivovaroff from Therma-Wave, Inc., and Nobuyuki Kawai from the Institute of Physical and Chemical Research, Japan. The scientists used Chandra to locate the pulsar exactly at the geometric center of the supernova remnant known as G11.2-0.3. This location provides very strong evidence that the pulsar, a neutron star that is rotating 14 times a second, was formed in the supernova of 386 AD, and therefore has an age of 1615 years. "Determining the true ages of astronomical objects is notoriously difficult, and for this reason, historical records of supernovas are of great importance,"said Kaspi."In roughly the past 2,000 years, fewer than 10 reports of probable supernovae have been archived mostly by Asian astronomers. Of those handful, the remnant of 1054 AD, the Crab Nebula, was until now the only pulsar whose birth could be associated with a historic event - and, hence, the only neutron star that has a firm age." Between mid-April and mid-May in the year 386 AD, a young "guest star", presumably a supernova, was recorded by Chinese observers in the direction of the sky now known as the constellation of Sagittarius. In the 1970s, radio astronomers discovered an expanding nebula of gas and high-energy particles, called G11.2-0.3, that is believed to be the remnant of that explosion. In 1997, a team of X-ray astronomers used Japan’s ASCA satellite to discover a pulsar

  15. Chandra pulsar survey (ChaPS)

    OpenAIRE

    Kargaltsev, Oleg; Durant, Martin; Pavlov, George G.; Garmire, Gordon

    2012-01-01

    Taking advantage of the high sensitivity of the Chandra Advanced CCD Imaging Spectrometer, we have conducted a snap-shot survey of pulsars previously undetected in X-rays. We detected 12 pulsars and established deep flux limits for 11 pulsars. Using these new results, we revisit the relationship between the X-ray luminosity, L_psr_x, and spin-down power, Edot. We find that the obtained limits further increase the extremely large spread in the non-thermal X-ray efficiencies, eta_psr_x=L_psr_x/...

  16. Acharya Prafulla Chandra at the College of Science

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 1. Acharya Prafulla Chandra at the College of Science. Gurunath ... Author Affiliations. Gurunath Mukherjee1. Department of Chemistry University College of Science & Technology 92, Acharya Prafulla Chandra Road Calcutta 700 009, India.

  17. The Stability of Chandra Telescope Pointing and Spacial Resolution

    Science.gov (United States)

    Zhao, Ping

    2018-01-01

    Chandra X-ray Observatory revolutionized the X-ray astronomy as being the first, and so far the only, X-ray telescope achieving sub-arcsecond spacial resolution. Chandra is comprised of three principal elements: the High Resolution Mirror Assembly (HRMA), Pointing Control and Aspect Determination (PCAD) system, and the Science Instrument Module (SIM), which is where the X-ray detectors mounted and is connected to the HRMA by a 10-meter long Optical Bench Assembly. To achieve and retain the unprecedented imaging quality, it is critical that these three principal elements to stay rigid and stable for the entire life time of the Chandra operation. I will review the issues of telescope pointing stability, optical Axis, aimpoint and their impacts to the Chandra operation, and evaluate the integrity and stability of the telescope. I will show images taken from all four detectors since launch to demonstrate the quality and stability of the Chandra spacial resolution.

  18. When Worlds Collide: Chandra Observes Titanic Merger

    Science.gov (United States)

    2002-04-01

    NASA's Chandra X-ray Observatory has provided the best X-ray image yet of two Milky Way-like galaxies in the midst of a head-on collision. Since all galaxies - including our own - may have undergone mergers, this provides insight into how the universe came to look as it does today. Astronomers believe the mega-merger in the galaxy known as Arp 220 triggered the formation of huge numbers of new stars, sent shock waves rumbling through intergalactic space, and could possibly lead to the formation of a supermassive black hole in the center of the new conglomerate galaxy. The Chandra data also suggest that merger of these two galaxies began only 10 million years ago, a short time in astronomical terms. "The Chandra observations show that things really get messed up when two galaxies run into each other at full speed," said David Clements of the Imperial College, London, one of the team members involved in the study. "The event affects everything from the formation of massive black holes to the dispersal of heavy elements into the universe." Arp 220 is considered to be a prototype for understanding what conditions were like in the early universe, when massive galaxies and supermassive black holes were presumably formed by numerous galaxy collisions. At a relatively nearby distance of about 250 million light years, Arp 220 is the closest example of an "ultra-luminous" galaxy, one that gives off a trillion times as much radiation as our Sun. The Chandra image shows a bright central region at the waist of a glowing, hour-glass-shaped cloud of multimillion-degree gas. Rushing out of the galaxy at hundreds of thousands of miles per hour, the super-heated as forms a "superwind," thought to be due to explosive activity generated by the formation of hundreds of millions of new stars. Farther out, spanning a distance of 75,000 light years, are giant lobes of hot gas that could be galactic remnants flung into intergalactic space by the early impact of the collision. Whether the

  19. X-raying galaxies: a Chandra legacy.

    Science.gov (United States)

    Wang, Q Daniel

    2010-04-20

    This presentation reviews Chandra's major contribution to the understanding of nearby galaxies. After a brief summary on significant advances in characterizing various types of discrete x-ray sources, the presentation focuses on the global hot gas in and around galaxies, especially normal ones like our own. The hot gas is a product of stellar and active galactic nuclear feedback--the least understood part in theories of galaxy formation and evolution. Chandra observations have led to the first characterization of the spatial, thermal, chemical, and kinetic properties of the gas in our galaxy. The gas is concentrated around the galactic bulge and disk on scales of a few kiloparsec. The column density of chemically enriched hot gas on larger scales is at least an order magnitude smaller, indicating that it may not account for the bulk of the missing baryon matter predicted for the galactic halo according to the standard cosmology. Similar results have also been obtained for other nearby galaxies. The x-ray emission from hot gas is well correlated with the star formation rate and stellar mass, indicating that the heating is primarily due to the stellar feedback. However, the observed x-ray luminosity of the gas is typically less than a few percent of the feedback energy. Thus the bulk of the feedback (including injected heavy elements) is likely lost in galaxy-wide outflows. The results are compared with simulations of the feedback to infer its dynamics and interplay with the circumgalactic medium, hence the evolution of galaxies.

  20. Chandra Captures Flare From Brown Dwarf

    Science.gov (United States)

    2000-07-01

    The first flare ever seen from a brown dwarf, or failed star, was detected by NASA's Chandra X-ray Observatory. The bright X-ray flare has implications for understanding the explosive activity and origin of magnetic fields of extremely low mass stars. Chandra detected no X-rays at all from LP 944-20 for the first nine hours of a twelve hour observation, then the source flared dramatically before it faded away over the next two hours. "We were shocked," said Dr. Robert Rutledge of the California Institute of Technology in Pasadena, the lead author on the discovery paper to appear in the July 20 issue of Astrophysical Journal Letters. "We didn't expect to see flaring from such a lightweight object. This is really the 'mouse that roared.'" Chandra LP 944-20 X-ray Image Press Image and Caption The energy emitted in the brown dwarf flare was comparable to a small solar flare, and was a billion times greater than observed X-ray flares from Jupiter. The flaring energy is believed to come from a twisted magnetic field. "This is the strongest evidence yet that brown dwarfs and possibly young giant planets have magnetic fields, and that a large amount of energy can be released in a flare," said Dr. Eduardo Martin, also of Caltech and a member of the team. Professor Gibor Basri of the University of California, Berkeley, the principal investigator for this observation, speculated that the flare "could have its origin in the turbulent magnetized hot material beneath the surface of the brown dwarf. A sub-surface flare could heat the atmosphere, allowing currents to flow and give rise to the X-ray flare -- like a stroke of lightning." LP 944-20 is about 500 million years old and has a mass that is about 60 times that of Jupiter, or 6 percent that of the Sun. Its diameter is about one-tenth that of the Sun and it has a rotation period of less than five hours. Located in the constellation Fornax in the southern skies, LP 944-20 is one of the best studied brown dwarfs because it is

  1. Doing Science with the Chandra Source Catalog

    Science.gov (United States)

    Evans, Ian N.; Chandra Source Catalog Team

    2018-01-01

    The excellent spatial resolution (~1 arcsecond on-axis) of the Chandra X-ray Observatory, combined with a reasonable field of view and low instrumental backgrounds, allow detection of serendipitous X-ray sources with a high detectable-source density with low confusion. The aim of the Chandra Source Catalog (CSC) is to disseminate this wealth of information to the user community in a form that is immediately usable for scientific investigation, and the catalog is intended to satisfy the needs of a broad- based group of scientists, including those who may be less familiar with astronomical data analysis in the X-ray regime.The second major release of the catalog, CSC 2.0, will be made available to the user community in early 2018, and preliminary lists of detections and sources are available now. CSC 2.0 will roughly triple the size of the current version of the catalog to an estimated 375,000 detections, corresponding to ~315,000 unique X-ray sources on the sky. For each detected X-ray source, the catalog provides a detailed set of properties including the source position and associated position error ellipse, source extent, multi-band aperture photometry probability density functions, spectral fits using several source models, hardness ratios, and intra- and inter-observation temporal variability measures. All numerical measures have associated two-sided confidence intervals. In addition to tabular data, the catalog provides FITS data products that are immediately suitable for further user analysis, including per-field and per-source images, photon event lists, responses, spectra, and light curves.We describe the content and organization of the catalog in more detail, discuss the analyses that were performed to extract the measured source properties, and demonstrate how the catalog content can be immediately and effectively utilized for scientific investigations. This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical

  2. Chandra Survey of Nearby Galaxies: The Catalog

    Energy Technology Data Exchange (ETDEWEB)

    She, Rui; Feng, Hua [Department of Engineering Physics and Center for Astrophysics, Tsinghua University, Beijing 100084 (China); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100087 (China)

    2017-02-01

    We searched the public archive of the Chandra X-ray Observatory as of 2016 March and assembled a sample of 719 galaxies within 50 Mpc with available Advanced CCD Imaging Spectrometer observations. By cross-correlation with the optical or near-infrared nuclei of these galaxies, 314 of them are identified to have an X-ray active galactic nucleus (AGN). The majority of them are low-luminosity AGNs and are unlikely X-ray binaries based upon their spatial distribution and luminosity functions. The AGN fraction is around 60% for elliptical galaxies and early-type spirals, but drops to roughly 20% for Sc and later types, consistent with previous findings in the optical. However, the X-ray survey is more powerful in finding weak AGNs, especially from regions with active star formation that may mask the optical AGN signature. For example, 31% of the H ii nuclei are found to harbor an X-ray AGN. For most objects, a single power-law model subject to interstellar absorption is adequate to fit the spectrum, and the typical photon index is found to be around 1.8. For galaxies with a non-detection, their stacked Chandra image shows an X-ray excess with a luminosity of a few times 10{sup 37} erg s{sup −1} on average around the nuclear region, possibly composed of faint X-ray binaries. This paper reports on the technique and results of the survey; in-depth analysis and discussion of the results will be reported in forthcoming papers.

  3. Jagadis Chandra Bose and His Pioneering Research on Microwaves

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 12. Jagadis Chandra Bose and His Pioneering Research on Microwaves. C George Verghese George C Verghese. Volume 10 Issue 12 December 2005 pp 83-85 ...

  4. The Chandra Source Catalog : Google Earth Interface

    Science.gov (United States)

    Glotfelty, Kenny; McLaughlin, W.; Evans, I.; Evans, J.; Anderson, C. S.; Bonaventura, N. R.; Davis, J. E.; Doe, S. M.; Fabbiano, G.; Galle, E. C.; Gibbs, D. G., II; Grier, J. D.; Hain, R.; Hall, D. M.; Harbo, P. N.; He, H.; Houck, J. C.; Karovska, M.; Kashyap, V. L.; Lauer, J.; McCollough, M. L.; McDowell, J. C.; Miller, J. B.; Mitschang, A. W.; Morgan, D. L.; Mossman, A. E.; Nichols, J. S.; Nowak, M. A.; Plummer, D. A.; Primini, F. A.; Refsdal, B. L.; Rots, A. R.; Siemiginowska, A. L.; Sundheim, B. A.; Tibbetts, M. S.; van Stone, D. W.; Winkelman, S. L.; Zografou, P.

    2009-09-01

    The Chandra Source Catalog (CSC) contains multi-resolution, exposure corrected, background subtracted, full-field images that are stored as individual FITS files and as three-color JPEG files. In this poster we discuss how we took these data and were able to, with relatively minimal effort, convert them for use with the Google Earth application in its ``Sky'' mode. We will highlight some of the challenges which include converting the data to the required Mercator projection, reworking the 3-color algorithm for pipeline processing, and ways to reduce the data volume through re-binning, using color-maps, and special Keyhole Markup Language (kml) tags to only load images on-demand. The result is a collection of some 11,000 3-color images that are available for all the individual observation in the CSC Release 1. We also have made available all ˜4000 Field-of-View outlines (with per-chip regions), which turns out are trivial to produce starting with a simple dmlist command. In the first week of release, approximately 40% of the images have been accessed at least once through some 50,000 individual web hits which have served over 4Gb of data to roughly 750 users in 60+ countries. We will also highlight some future directions we are exploring, including real-time catalog access to individual source properties and eventual access to file based products such as FITS images, spectra, and light-curves.

  5. CIAO: CHANDRA/X-RAY DATA ANALYSIS FOR EVERYONE

    Science.gov (United States)

    McDowell, Jonathan; CIAO Team

    2018-01-01

    Eighteen years after the launch of Chandra, the archive is full of scientifically rich data and new observations continue. Improvements in recent years to the data analysis package CIAO (Chandra Interactive Analysis of Observations) and its extensive accompanying documentation make it easier for astronomers without a specialist background in high energy astrophysics to take advantage of this resource.The CXC supports hundreds of CIAO users around the world at all levels of training from high school and undergraduate students to the most experienced X-ray astronomers. In general, we strive to provide a software system which is easy for beginners, yet powerful for advanced users.Chandra data cover a range of instrument configurations and types of target (pointlike, extended and moving), requiring a flexible data analysis system. In addition to CIAO tools using the familiar FTOOLS/IRAF-style parameter interface, CIAO includes applications such as the Sherpa fitting engine which provide access to the data via Python scripting.In this poster we point prospective (and existing!) users to the high level Python scripts now provided to reprocess Chandra or other X-ray mission data, determine source fluxes and upper limits, and estimate backgrounds; and to the latest documentation including the CIAO Gallery, a new entry point featuring the system's different capabilities.This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center.

  6. 204 Chandra N Farm and Swapan K Ghosh

    Indian Academy of Sciences (India)

    204 Chandra N Farm and Swapan K Ghosh. Figure 4. Calculated density profiles of the ions and the solvent molecules at selected values of wall separation; ( ----- ' -): counter-ions, (--~-~-~»): co—ions, ( ): solvent molecules. (system parameters as in figure 3). experimentally observed forces in neutral liquids. With a view to ...

  7. Mandibular Fractures at Veer Chandra Singh Garhwali Government ...

    African Journals Online (AJOL)

    to the trauma centre of Veer Chandra Singh Garhwali Government Medical Science and ... most frequently affected sites were parasymphysis and angle. .... mandibular fracture. When history of fall from height was considered symphysis, condyle and body were the most affected sites. On history taking it was found that most ...

  8. Chandra Cluster Cosmology Project III: Cosmological Parameter Constraints

    DEFF Research Database (Denmark)

    Vikhlinin, A.; Kravtsov, A. V.; Burenin, R. A.

    2009-01-01

    function evolution to be used as a useful growth of a structure-based dark energy probe. In this paper, we present cosmological parameter constraints obtained from Chandra observations of 37 clusters with langzrang = 0.55 derived from 400 deg2 ROSAT serendipitous survey and 49 brightest z ≈ 0.05 clusters...

  9. Chandra: Ten Years of Amazing Science with a Great Observatory

    Science.gov (United States)

    Weisskopf, Martin C.

    2009-01-01

    We review briefly review the history of the development of the Chandra X-Ray Observatory, highlighting certain details that many attendees of this Conference might not be aware of. We then present a selection of scientific highlights of the first 10 years of this remarkable and unique mission.

  10. Chandra Opens New Line of Investigation on Dark Energy

    Science.gov (United States)

    2004-05-01

    Astronomers have detected and probed dark energy by applying a powerful, new method that uses images of galaxy clusters made by NASA's Chandra X-ray Observatory. The results trace the transition of the expansion of the Universe from a decelerating to an accelerating phase several billion years ago, and give intriguing clues about the nature of dark energy and the fate of the Universe. "Dark energy is perhaps the biggest mystery in physics," said Steve Allen of the Institute of Astronomy (IoA) at the University of Cambridge in England, and leader of the study. "As such, it is extremely important to make an independent test of its existence and properties." Abell 2029 Chandra X-ray Image of Abell 2029 Allen and his colleagues used Chandra to study 26 clusters of galaxies at distances corresponding to light travel times of between one and eight billion years. These data span the time when the Universe slowed from its original expansion, before speeding up again because of the repulsive effect of dark energy. "We're directly seeing that the expansion of the Universe is accelerating by measuring the distances to these galaxy clusters," said Andy Fabian also of the IoA, a co-author on the study. The new Chandra results suggest that the dark energy density does not change quickly with time and may even be constant, consistent with the "cosmological constant" concept first introduced by Albert Einstein. If so, the Universe is expected to continue expanding forever, so that in many billions of years only a tiny fraction of the known galaxies will be observable. More Animations Animation of the "Big Rip" If the dark energy density is constant, more dramatic fates for the Universe would be avoided. These include the "Big Rip," where dark energy increases until galaxies, stars, planets and eventually atoms are eventually torn apart. The "Big Crunch," where the Universe eventually collapses on itself, would also be ruled out. Chandra's probe of dark energy relies on the unique

  11. The Chandra Source Catalog 2.0: Building The Catalog

    Science.gov (United States)

    Grier, John D.; Plummer, David A.; Allen, Christopher E.; Anderson, Craig S.; Budynkiewicz, Jamie A.; Burke, Douglas; Chen, Judy C.; Civano, Francesca Maria; D'Abrusco, Raffaele; Doe, Stephen M.; Evans, Ian N.; Evans, Janet D.; Fabbiano, Giuseppina; Gibbs, Danny G., II; Glotfelty, Kenny J.; Graessle, Dale E.; Hain, Roger; Hall, Diane M.; Harbo, Peter N.; Houck, John C.; Lauer, Jennifer L.; Laurino, Omar; Lee, Nicholas P.; Martínez-Galarza, Juan Rafael; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph; McLaughlin, Warren; Morgan, Douglas L.; Mossman, Amy E.; Nguyen, Dan T.; Nichols, Joy S.; Nowak, Michael A.; Paxson, Charles; Primini, Francis Anthony; Rots, Arnold H.; Siemiginowska, Aneta; Sundheim, Beth A.; Tibbetts, Michael; Van Stone, David W.; Zografou, Panagoula

    2018-01-01

    To build release 2.0 of the Chandra Source Catalog (CSC2), we require scientific software tools and processing pipelines to evaluate and analyze the data. Additionally, software and hardware infrastructure is needed to coordinate and distribute pipeline execution, manage data i/o, and handle data for Quality Assurance (QA) intervention. We also provide data product staging for archive ingestion.Release 2 utilizes a database driven system used for integration and production. Included are four distinct instances of the Automatic Processing (AP) system (Source Detection, Master Match, Source Properties and Convex Hulls) and a high performance computing (HPC) cluster that is managed to provide efficient catalog processing. In this poster we highlight the internal systems developed to meet the CSC2 challenge.This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center.

  12. Cross-matching with the Chandra Source Catalog

    Science.gov (United States)

    Rots, Arnold H.; Nguyen, Dan; Budavari, Tamas; Burke, Douglas J.; Civano, Francesca M.; Hain, Roger

    2017-08-01

    Cross-matching the Chandra Source Catalog (CSC) with other catalogs presents considerable challenges, since the Point Spread Function (PSF) of the Chandra X-ray Observatory varies significantly over the field of view. For the second release of the CSC we have developed a cross-match tool that is based on the Bayesian algorithms by Budavari, Heinis, and Szalay (ApJ 679, 301 and 705, 739), making use of the error ellipses for the derived positions of the detections.However, calculating match probabilities only on the basis of error ellipses breaks down when the PSFs are significantly different. Not only can bonafide matches easily be missed, but the scene is also muddied by ambiguous multiple matches. These are issues that are not commonly addressed in cross-match tools. We have applied a satisfactory modification to the algorithm that, although not perfect, ameliorates the problems for the vast majority of such cases.A separate issue is that as the number of overlapping catalogs increases, the number of matches to be considered increases at an alarming rate, requiring procedural adjustments to ensure that the cross-matching finishes within a Hubble time. We have found a solution among graph theory algorithms.This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center.

  13. Chandra Grating Spectroscopy of Three Hot White Dwarfs

    Science.gov (United States)

    Adamczak, J.; Werner, K.; Rauch, T.; Schuh, S.; Drake, J. J.; Kruk, J. W.

    2013-01-01

    High-resolution soft X-ray spectroscopic observations of single hot white dwarfs are scarce. With the Chandra Low-Energy Transmission Grating, we have observed two white dwarfs, one is of spectral type DA (LB1919) and the other is a non-DA of spectral type PG1159 (PG1520+525). The spectra of both stars are analyzed, together with an archival Chandra spectrum of another DA white dwarf (GD246). Aims. The soft X-ray spectra of the two DA white dwarfs are investigated in order to study the effect of gravitational settling and radiative levitation of metals in their photospheres. LB1919 is of interest because it has a significantly lower metallicity than DAs with otherwise similar atmospheric parameters. GD246 is the only white dwarf known that shows identifiable individual iron lines in the soft X-ray range. For the PG1159 star, a precise effective temperature determination is performed in order to confine the position of the blue edge of the GW Vir instability region in the HRD. Methods. The Chandra spectra are analyzed with chemically homogeneous as well as stratified NLTE model atmospheres that assume equilibrium between gravitational settling and radiative acceleration of chemical elements. Archival EUV and UV spectra obtained with EUVE, FUSE, and HST are utilized to support the analysis. Results. No metals could be identified in LB1919. All observations are compatible with a pure hydrogen atmosphere. This is in stark contrast to the vast majority of hot DA white dwarfs that exhibit light and heavy metals and to the stratified models that predict significant metal abundances in the atmosphere. For GD246 we find that neither stratified nor homogeneous models can fit the Chandra spectrum. The Chandra spectrum of PG1520+525 constrains the effective temperature to T(sub eff) = 150 000 +/- 10 000 K. Therefore, this nonpulsating star together with the pulsating prototype of the GWVir class (PG1159-035) defines the location of the blue edge of the GWVir instability region

  14. Chandra Clinches Case for Missing Link Black Hole

    Science.gov (United States)

    2000-09-01

    The strongest evidence yet that the universe is home to a new type of black hole was reported by several groups of scientists today Using NASA's Chandra X-ray Observatory, scientists have zeroed in on a mid-mass black hole in the galaxy M82. This black hole - located 600 light years away from the center of a galaxy - may represent the missing link between smaller stellar black holes and the supermassive variety found at the centers of galaxies. "This opens a whole new field of research," said Martin Ward of the University of Leicester, UK, a lead author involved with the observations. "No one was sure that such black holes existed, especially outside the centers of galaxies." The black hole in M82 packs the mass of at least 500 suns into a region about the size of the Moon. Such a black hole would require extreme conditions for its creation, such as the collapse of a "hyperstar" or the merger of scores of black holes. The result comes as Chandra starts its second year of operation and is testimony to how Chandra's power and precision is changing the field of astronomy. "This black hole might eventually sink to the center of the galaxy," said Dr. Hironori Matsumoto of the Massachusetts Institute of Technology, the lead author on one of three Chandra papers scheduled to be published on the mid-mass black hole, "where it could grow to become a supermassive black hole." Although previous X-ray data from the German-U.S. Roentgen Satellite and the Japan-U.S. ASCA Satellite suggested that a mid-mass black hole might exist in M82, the crucial breakthrough came when astronomers compared the new high resolution Chandra data with optical, radio, and infrared maps of the region. They determined that most of the X-rays were coming from a single bright source. Repeated observations of M82 over a period of eight months showed the bright X-ray source gradually peaking in X-ray brightness before dimming. Another critical discovery was that the intensity of the X rays was rising and

  15. Chandra Survey of Distant Galaxies Provides Evidence for Vigorous Starbursts

    Science.gov (United States)

    2000-05-01

    Using NASA's Chandra X-ray Observatory, astronomers have made the first long-duration X-ray survey of the Hubble Deep Field North. They detected X rays from six of the galaxies in the field, and were surprised by the lack of X rays from some of the most energetic galaxies in the field. The X-ray emitting objects discovered by the research team are a distant galaxy thought to contain a central giant black hole, three elliptically shaped galaxies, an extremely red distant galaxy, and a nearby spiral galaxy. "We were expecting about five X-ray sources in this field,"said Professor Niel Brandt of Penn State University, University Park, and one of the leaders of the research team that conducted the survey. "However, it was very surprising to find that none of the X-ray sources lined up with any of the submillimeter sources." The submillimeter sources are extremely luminous, dusty galaxies that produce large amounts of infrared radiation. Because they are over ten billion light years from Earth, their infrared radiation is shifted to longer, submillimeter wavelengths as it traverses the expanding universe. The primary source of the large power of the submillimeter sources is thought to be an unusually high rate of star formation, or the infall, or accretion of matter into a giant black hole in the center of the galaxy. X-ray observations provide the most direct measure of black hole accretion power. X rays, because of their high-energy, would be expected to pass through the gas and dust in these galaxies, unlike visible light. "With Chandra we have been able to place the best X-ray constraints ever on submillimeter sources," said Ann Hornschemeier, also of Penn State, and the lead author of an upcoming Astrophysical Journal paper describing the discovery. "Our results indicate that less than 15 percent of the submillimeter sources can be luminous X-ray sources." "That means," Brandt explains, "Either there is an enormous amount of star formation in those galaxies, or

  16. Chandra Observatory Uncovers Hot Stars In The Making

    Science.gov (United States)

    2000-11-01

    Cambridge, Mass.--In resolving the hot core of one of the Earth's closest and most massive star-forming regions, the Chandra X-ray Observatory showed that almost all the young stars' temperatures are more extreme than expected. Orion Trapezium JPEG, TIFF, PS The Orion Trapezium as observed on October 31st UT 05:47:21 1999. The colors represent energy, where blue and white indicate very high energies and therefore exterme temperatures. The size of the X-ray source in the image also reflects its brightness, i.e. more bright sources appear larger in size. The is an artifact caused by the limiting blur of the telescope optics. The projected diameter of the field of view is about 80 light days. Credit: NASA/MIT Orion Trapezium JPEG, TIFF, PS The Orion Trapezium as observed on November 24th UT 05:37:54 1999. The colors represent energy, where blue and white indicate very high energies and therefore exterme temperatures. The size of the X-ray source in the image also reflects its brightness, i.e. more bright sources appear larger in size. The is an artifact caused by the limiting blur of the telescope optics. The projected diameter of the field of view is about 80 light days. Credit: NASA/MIT The Orion Trapezium Cluster, only a few hundred thousand years old, offers a prime view into a stellar nursery. Its X-ray sources detected by Chandra include several externally illuminated protoplanetary disks ("proplyds") and several very massive stars, which burn so fast that they will die before the low mass stars even fully mature. One of the major highlights of the Chandra observations are identification of proplyds as X-ray point source in the near vicinity of the most massive star in the Trapezium. Previous observations did not have the ability to separate the contributions of the different objects. "We've seen high temperatures in stars before, but what clearly surprised us was that nearly all the stars we see appear at rather extreme temperatures in X-rays, independent of

  17. Chandra Uncovers New Evidence For Event Horizons Surrounding Black Holes

    Science.gov (United States)

    2001-01-01

    SAN DIEGO -- Astronomers have used NASA's Chandra X-ray Observatory to study some of the darkest black holes yet observed. Their work strongly confirms the reality of the "event horizon," the one-way membrane around black holes predicted by Einstein's theory of relativity. The findings were presented today at the American Astronomical Society meeting by Drs. Michael Garcia, Jeffrey McClintock, Ramesh Narayan, and Stephen Murray of the Harvard-Smithsonian Center for Astrophysics and Dr. Paul Callanan of University College, Cork, Ireland. With results that fundamentally differ from earlier black hole studies, Garcia and his colleagues have shown that some recently discovered black holes are not only ultra-dense, but actually possess event horizons that "vacuum up" energy from their surroundings. "It is a bit odd to say we've discovered something by seeing almost nothing at all -- less than the smile of the Cheshire cat, so to speak," said Garcia, lead author on a paper submitted to the Astrophysical Journal, "but, in essence, this is what we have done." Using data from Chandra and previous X-ray satellites like ROSAT, the Chandra team studied a dozen "X-ray novas," so named because they occasionally erupt as brilliant X-ray sources then settle into decades of dormancy. The great outpouring of X rays is due to a stream of gas that is pulled from the surface of a Sun-like companion star onto a compact object, either a black hole or a neutron star. By comparing the energy output from the dormant X-ray novas, the team discovered that the sources with black holes emitted only one percent as much energy while dormant as did the X-ray novae with neutron stars. "The most straightforward explanation of these observations is that the black hole candidates we have studied have event horizons that swallow just about all of the energy that surrounds them," said Murray. "Indeed, one could even say that this work shows why black holes deserve to be called ‘black.’" "The event

  18. The Chandra Source Catalog 2.0: Spectral Properties

    Science.gov (United States)

    McCollough, Michael L.; Siemiginowska, Aneta; Burke, Douglas; Nowak, Michael A.; Primini, Francis Anthony; Laurino, Omar; Nguyen, Dan T.; Allen, Christopher E.; Anderson, Craig S.; Budynkiewicz, Jamie A.; Chen, Judy C.; Civano, Francesca Maria; D'Abrusco, Raffaele; Doe, Stephen M.; Evans, Ian N.; Evans, Janet D.; Fabbiano, Giuseppina; Gibbs, Danny G., II; Glotfelty, Kenny J.; Graessle, Dale E.; Grier, John D.; Hain, Roger; Hall, Diane M.; Harbo, Peter N.; Houck, John C.; Lauer, Jennifer L.; Lee, Nicholas P.; Martínez-Galarza, Juan Rafael; McDowell, Jonathan C.; Miller, Joseph; McLaughlin, Warren; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Paxson, Charles; Plummer, David A.; Rots, Arnold H.; Sundheim, Beth A.; Tibbetts, Michael; Van Stone, David W.; Zografou, Panagoula; Chandra Source Catalog Team

    2018-01-01

    The second release of the Chandra Source Catalog (CSC) contains all sources identified from sixteen years' worth of publicly accessible observations. The vast majority of these sources have been observed with the ACIS detector and have spectral information in 0.5-7 keV energy range. Here we describe the methods used to automatically derive spectral properties for each source detected by the standard processing pipeline and included in the final CSC. The sources with high signal to noise ratio (exceeding 150 net counts) were fit in Sherpa (the modeling and fitting application from the Chandra Interactive Analysis of Observations package) using wstat as a fit statistic and Bayesian draws method to determine errors. Three models were fit to each source: an absorbed power-law, blackbody, and Bremsstrahlung emission. The fitted parameter values for the power-law, blackbody, and Bremsstrahlung models were included in the catalog with the calculated flux for each model. The CSC also provides the source energy fluxes computed from the normalizations of predefined absorbed power-law, black-body, Bremsstrahlung, and APEC models needed to match the observed net X-ray counts. For sources that have been observed multiple times we performed a Bayesian Blocks analysis will have been performed (see the Primini et al. poster) and the most significant block will have a joint fit performed for the mentioned spectral models. In addition, we provide access to data products for each source: a file with source spectrum, the background spectrum, and the spectral response of the detector. Hardness ratios were calculated for each source between pairs of energy bands (soft, medium and hard). This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center.

  19. Chandra Finds Well-Established Black Holes In Distant Quasars

    Science.gov (United States)

    2002-03-01

    Pushing further back toward the first generation of objects to form in the universe, NASA's Chandra X-ray Observatory has observed the three most distant known quasars and found them to be prodigious producers of X-rays. This indicates that the supermassive black holes powering them were already in place when the Universe was only about one billion years old. "Chandra's superb sensitivity has allowed the detection of X-rays from the dawn of the modern universe, when the first massive black holes and galaxies were forming," said Niel Brandt of Penn State University, leader of one the teams involved. "These results indicate that future X-ray surveys should be able to detect the first black holes to form in the Universe." The three quasars were recently discovered at optical wavelengths by the Sloan Digital Sky Survey and are 13 billion light years from Earth, making them the most distant known quasars. The X-rays Chandra detected were emitted when the universe was only a billion years old, about 7 percent of the present age of the Universe. Since X-rays reveal conditions in the immediate vicinity of supermassive black holes, Brandt proposed that Chandra look at these objects in three snapshots of about two hours each to see if they were different from their older counterparts. The observations on January 29, 2002 were made public immediately and the four different teams quickly went to work on them. Brandt's team concluded that the quasars looked similar to ones that were at least twice as old, so the conditions around the central black hole had not changed much in that time, contrary to some theoretical expectations. A team led by Smita Mathur of Ohio State University reached a similar conclusion. "These young quasars do not appear to be any different from their older cousins, based upon our current understanding and assumptions," said Mathur. "Perhaps the most remarkable thing about them may be that they are so absolutely unremarkable." Jill Bechtold of the

  20. The Chandra Source Catalog 2.0: Interfaces

    Science.gov (United States)

    D'Abrusco, Raffaele; Zografou, Panagoula; Tibbetts, Michael; Allen, Christopher E.; Anderson, Craig S.; Budynkiewicz, Jamie A.; Burke, Douglas; Chen, Judy C.; Civano, Francesca Maria; Doe, Stephen M.; Evans, Ian N.; Evans, Janet D.; Fabbiano, Giuseppina; Gibbs, Danny G., II; Glotfelty, Kenny J.; Graessle, Dale E.; Grier, John D.; Hain, Roger; Hall, Diane M.; Harbo, Peter N.; Houck, John C.; Lauer, Jennifer L.; Laurino, Omar; Lee, Nicholas P.; Martínez-Galarza, Rafael; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph; McLaughlin, Warren; Morgan, Douglas L.; Mossman, Amy E.; Nguyen, Dan T.; Nichols, Joy S.; Nowak, Michael A.; Paxson, Charles; Plummer, David A.; Primini, Francis Anthony; Rots, Arnold H.; Siemiginowska, Aneta; Sundheim, Beth A.; Van Stone, David W.

    2018-01-01

    Easy-to-use, powerful public interfaces to access the wealth of information contained in any modern, complex astronomical catalog are fundamental to encourage its usage. In this poster,I present the public interfaces of the second Chandra Source Catalog (CSC2). CSC2 is the most comprehensive catalog of X-ray sources detected by Chandra, thanks to the inclusion of Chandra observations public through the end of 2014 and to methodological advancements. CSC2 provides measured properties for a large number of sources that sample the X-ray sky at fainter levels than the previous versions of the CSC, thanks to the stacking of single overlapping observations within 1’ before source detection. Sources from stacks are then crossmatched, if multiple stacks cover the same area of the sky, to create a list of unique, optimal CSC2 sources. The properties of sources detected in each single stack and each single observation are also measured. The layered structure of the CSC2 catalog is mirrored in the organization of the CSC2 database, consisting of three tables containing all properties for the unique stacked sources (“Master Source”), single stack sources (“Stack Source”) and sources in any single observation (“Observation Source”). These tables contain estimates of the position, flags, extent, significances, fluxes, spectral properties and variability (and associated errors) for all classes of sources. The CSC2 also includes source region and full-field data products for all master sources, stack sources and observation sources: images, photon event lists, light curves and spectra.CSCview, the main interface to the CSC2 source properties and data products, is a GUI tool that allows to build queries based on the values of all properties contained in CSC2 tables, query the catalog, inspect the returned table of source properties, browse and download the associated data products. I will also introduce the suite of command-line interfaces to CSC2 that can be used in

  1. Chandra Sees Shape of Universe During Formative, Adolescent Years

    Science.gov (United States)

    2003-03-01

    Scientists using NASA's Chandra X-ray Observatory have taken a snapshot of the adolescent universe from about five billion years ago when the familiar web-like structure of galaxy chains and voids first emerged. The observation reveals distant and massive galaxies dotting the sky, clustered together under the gravitational attraction of deep, unseen pockets of dark matter. This provides important clues of how the universe matured from its chaotic beginnings to its elegant structure we see today. These results are presented today in a press conference at the meeting of the High Energy Astrophysics Division of the American Astronomical Society at Mt. Tremblant, Quebec. "Piece by piece, we are assembling a photo album of the universe through the ages," said Yuxuan Yang, a doctorate candidate at the University of Maryland, College Park, who conducted the analysis. "Last month we saw a picture of the infant universe taken with the Wilkinson Microwave Anisotropy Probe. Now we can add a snapshot of its adolescence." The Chandra observation traced a patch of sky known as the Lockman Hole in the constellation Ursa Major (containing the Big Dipper). Chandra saw a rich density of active galaxies, seven times denser than what has been detected in previous optical and radio surveys at similar distances. This provides the clearest picture yet at the large-scale structure of the universe at such distances (and age), according to Dr. Richard Mushotzky of NASA Goddard Space Flight Center in Greenbelt, Md., who led the observation. Lockman Hole JPEG, TIFF, PS An image that has been "blurred" to allow better view of the structures outlined by the X-ray sources. The color represents the spectra of the AGN. The red color indicates the sources on average radiates at longer wavelength while green and blue colors indicates the sources radiates at shorter wavelength. The Green and blue regions appear to form a wall, or shows more lumpiness than the "red" sources. If one could capture the

  2. 75 FR 7471 - Chandra Coffee and Rabun Boatworks, Complainants v. Georgia Power Company, Respondent; Notice of...

    Science.gov (United States)

    2010-02-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Chandra Coffee and Rabun Boatworks, Complainants v. Georgia Power Company... January 8, 2010, Chandra Coffee and Rabun Boatworks (Complainants) filed with the Federal Regulatory...

  3. Chandra and XMM–Newton Observations of H 2 O Maser Galaxy ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... For H2O megamaser galaxy Mrk 348, Chandra and XMM–Newton data are analysed. The nuclear fitting results of XMM–Newton data suggest the possible existence of a heavily obscured AGN. But the nuclear spectrum extracted from Chandra cannot be well-fitted by the best fitting model for XMM–Newton.

  4. VARIABILITY OF OPTICAL COUNTERPARTS IN THE CHANDRA GALACTIC BULGE SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Britt, C. T.; Hynes, R. I.; Johnson, C. B.; Baldwin, A.; Collazzi, A.; Gossen, L. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Jonker, P. G.; Torres, M. A. P. [SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Nelemans, G. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen (Netherlands); Maccarone, T. [Department of Physics, Texas Tech University, Box 41051, Science Building, Lubbock, TX 79409-1051 (United States); Steeghs, D.; Greiss, S. [Astronomy and Astrophysics, Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Heinke, C. [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Bassa, C. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Villar, A. [Department of Physics, Massachussettes Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States); Gabb, M. [Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991 (United States)

    2014-09-01

    We present optical light curves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey (GBS). Using data from the Mosaic-II instrument on the Blanco 4 m Telescope at CTIO, we gathered time-resolved photometric data on timescales from ∼2 hr to 8 days over the 3/4 of the X-ray survey containing sources from the initial GBS catalog. Among the light curve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. Eighty-seven percent of X-ray sources have at least one potential optical counterpart. Twenty-seven percent of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and discuss the characteristics of the variable population.

  5. Chandra Observation of Polaris: Census of Low-mass Companions

    Science.gov (United States)

    Evans, Nancy Remage; Guinan, Edward; Engle, Scott; Wolk, Scott J.; Schlegel, Eric; Mason, Brian D.; Karovska, Margarita; Spitzbart, Bradley

    2010-05-01

    We have observed Cepheid Polaris (α UMi A: F7 Ib [Aa] + F6 V [Ab]) with Chandra ACIS-I for 10 ks. An X-ray source was found at the location of Polaris with log LX = 28.89 erg s-1 (0.3-8 keV) and kT = 0.6 keV. A spectrum this soft could come from either the supergiant or the dwarf, as shown by comparable coronal stars. Two resolved low-mass visual companions, "C" and "D," are not physical members of the system based on the lack of X-rays (indicating an age older than the Cepheid) and inconsistent proper motions. Polaris B is not an X-ray source, consistent with its early F spectral type, and probably does not have a lower mass companion itself. A possible more distant member is identified, and an additional less plausible one. This provides a complete census of companions out to 0.1 pc covering a mass ratio range of an order of magnitude and a ΔV of nearly 15 mag. Based on observations made with the NASA Chandra Satellite.

  6. Chandra HRC Observations of X-rays from Jupiter's Aurora

    Science.gov (United States)

    Gladstone, G. R.; Majeed, T.; Lewis, W. S.; Jahn, J.-M.; Waite, J. H., Jr.; Grodent, D. C.; Crary, F. J.; Clarke, J. T.; Young, D. T.; Elsner, R. F.

    2001-01-01

    In support of the Cassini flyby of Jupiter, the Chandra HRC was used to observe the Jovian system for 10 hours on December 18, 2000, from 10-20 UT. Analysis of the data has yielded the following results: 1) a strong, high-latitude northern auroral "hot spot." which is relatively fixed near 60-70 degrees north latitude and 160-180 degrees system III longitude, and which pulsates with a period of about 40 minutes and has an average emitted power of about 2 GW; 2) relatively uniform low-latitude emissions, with a total power output of about 5 GW; 3) a southern aurora which shows both high latitude emissions and lower-latitude emissions originating in the L=8-12 region just outside the Io Plasma Torus, with an emitted power of about 1 GW. These power estimates are based on an assumed emission wavelength of 574 eV (corresponding to a bright emission line of OVII ions), and are subject to revision as Chandra ACIS spectra of Jupiter are analyzed further. We will present these and other results from this unique data set.

  7. Chandra Finds Ghosts Of Eruption In Galaxy Cluster

    Science.gov (United States)

    2002-01-01

    "Ghostly" relics of an ancient eruption that tore through a cluster of galaxies were recently uncovered by NASA's Chandra X-ray Observatory. The discovery implies that galaxy clusters are the sites of enormously energetic and recurring explosions, and may provide an explanation why galaxy clusters behave like giant cosmic magnets. "Chandra's image revealed vast regions in the galaxy cluster Abell 2597 that contain almost no X-ray or radio emission. We call them ghost cavities," said Brian McNamara of Ohio University in Athens today during a press conference at the American Astronomical Society meeting in Washington. "They appear to be remnants of an old explosion where the radio emission has faded away over millions of years." The ghost cavities were likely created by extremely powerful explosions, due to material falling toward a black hole millions of times more massive than the Sun. As the matter swirled around the black hole, located in a galaxy near the center of the cluster, it generated enormous electromagnetic fields that expelled material from the vicinity of the black hole at high speeds. This explosive activity in Abell 2597 created jets of highly energetic particles that cleared out voids in the hot gas. Because they are lighter than the surrounding material, the cavities will eventually push their way to the edge of the cluster, just as air bubbles in water make their way to the surface. Researchers also found evidence that this explosion was not a one-time event. "We detected a small, bright radio source near the center of the cluster that indicates a new explosion has occurred recently," said team member Michael Wise of the Massachusetts Institute of Technology in Cambridge, "so the cycle of eruption is apparently continuing." Though dim, the ghost cavities are not completely empty. They contain a mixture of very hot gas, high-energy particles and magnetic fields -- otherwise the cavities would have collapsed under the pressure of the surrounding hot

  8. Chandra "Hears" A Black Hole For The First Time

    Science.gov (United States)

    2003-09-01

    NASA's Chandra X-ray Observatory detected sound waves, for the first time, from a super-massive black hole. The "note" is the deepest ever detected from an object in the universe. The tremendous amounts of energy carried by these sound waves may solve a longstanding problem in astrophysics. The black hole resides in the Perseus cluster, located 250 million light years from Earth. In 2002, astronomers obtained a deep Chandra observation that shows ripples in the gas filling the cluster. These ripples are evidence for sound waves that have traveled hundreds of thousands of light years away from the cluster's central black hole. perseus animation Illustration of Ripples in Perseus "We have observed the prodigious amounts of light and heat created by black holes, now we have detected the sound," said Andrew Fabian of the Institute of Astronomy (IoA) in Cambridge, England, and leader of the study. In musical terms, the pitch of the sound generated by the black hole translates into the note of B flat. But, a human would have no chance of hearing this cosmic performance, because the note is 57 octaves lower than middle-C (by comparison a typical piano contains only about seven octaves). At a frequency over a million, billion times deeper than the limits of human hearing, this is the deepest note ever detected from an object in the universe. "The Perseus sound waves are much more than just an interesting form of black hole acoustics," said Steve Allen, also of the IoA and a co-investigator in the research. "These sound waves may be the key in figuring out how galaxy clusters, the largest structures in the universe, grow," Allen said. For years astronomers have tried to understand why there is so much hot gas in galaxy clusters and so little cool gas. Hot gas glowing with X-rays should cool, and the dense central gas should cool the fastest. The pressure in this cool central gas should then fall, causing gas further out to sink in towards the galaxy, forming trillions of

  9. Chandra Finds Surprising Black Hole Activity In Galaxy Cluster

    Science.gov (United States)

    2002-09-01

    Scientists at the Carnegie Observatories in Pasadena, California, have uncovered six times the expected number of active, supermassive black holes in a single viewing of a cluster of galaxies, a finding that has profound implications for theories as to how old galaxies fuel the growth of their central black holes. The finding suggests that voracious, central black holes might be as common in old, red galaxies as they are in younger, blue galaxies, a surprise to many astronomers. The team made this discovery with NASA'S Chandra X-ray Observatory. They also used Carnegie's 6.5-meter Walter Baade Telescope at the Las Campanas Observatory in Chile for follow-up optical observations. "This changes our view of galaxy clusters as the retirement homes for old and quiet black holes," said Dr. Paul Martini, lead author on a paper describing the results that appears in the September 10 issue of The Astrophysical Journal Letters. "The question now is, how do these black holes produce bright X-ray sources, similar to what we see from much younger galaxies?" Typical of the black hole phenomenon, the cores of these active galaxies are luminous in X-ray radiation. Yet, they are obscured, and thus essentially undetectable in the radio, infrared and optical wavebands. "X rays can penetrate obscuring gas and dust as easily as they penetrate the soft tissue of the human body to look for broken bones," said co-author Dr. Dan Kelson. "So, with Chandra, we can peer through the dust and we have found that even ancient galaxies with 10-billion-year-old stars can have central black holes still actively pulling in copious amounts of interstellar gas. This activity has simply been hidden from us all this time. This means these galaxies aren't over the hill after all and our theories need to be revised." Scientists say that supermassive black holes -- having the mass of millions to billions of suns squeezed into a region about the size of our Solar System -- are the engines in the cores of

  10. The Chandra Source Catalog 2.0: Data Processing Pipelines

    Science.gov (United States)

    Miller, Joseph; Allen, Christopher E.; Budynkiewicz, Jamie A.; Gibbs, Danny G., II; Paxson, Charles; Chen, Judy C.; Anderson, Craig S.; Burke, Douglas; Civano, Francesca Maria; D'Abrusco, Raffaele; Doe, Stephen M.; Evans, Ian N.; Evans, Janet D.; Fabbiano, Giuseppina; Glotfelty, Kenny J.; Graessle, Dale E.; Grier, John D.; Hain, Roger; Hall, Diane M.; Harbo, Peter N.; Houck, John C.; Lauer, Jennifer L.; Laurino, Omar; Lee, Nicholas P.; Martínez-Galarza, Juan Rafael; McCollough, Michael L.; McDowell, Jonathan C.; McLaughlin, Warren; Morgan, Douglas L.; Mossman, Amy E.; Nguyen, Dan T.; Nichols, Joy S.; Nowak, Michael A.; Plummer, David A.; Primini, Francis Anthony; Rots, Arnold H.; Siemiginowska, Aneta; Sundheim, Beth A.; Tibbetts, Michael; Van Stone, David W.; Zografou, Panagoula

    2018-01-01

    With the construction of the Second Chandra Source Catalog (CSC2.0), came new requirements and new techniques to create a software system that can process 10,000 observations and identify nearly 320,000 point and compact X-ray sources. A new series of processing pipelines have been developed to allow for deeper more complete exploration of the Chanda observations. In CSC1.0 there were 4 general pipelines, whereas in CSC2.0 there are 20 data processing pipelines that have been organized into 3 distinct phases of operation - detection, master matching and source property characterization.With CSC2.0, observations within one arcminute of each other are stacked before searching for sources. The detection phase of processing combines the data, adjusts for shifts in fine astrometry, detects sources, and assesses the likelihood that sources are real. During the master source phase, detections across stacks of observations are analyzed for coverage of the same source to produce a master source. Finally, in the source property phase, each source is characterized with aperture photometry, spectrometry, variability and other properties at theobservation, stack and master levels over several energy bands.We present how these pipelines were constructed and the challenges we faced in how we processed data ranging from virtually no counts to millions of counts, how pipelines were tuned to work optimally on a computational cluster, and how we ensure the data produced was correct through various quality assurance steps.This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center.

  11. THE CHANDRA COSMOS LEGACY SURVEY: OPTICAL/IR IDENTIFICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, S.; Civano, F.; Urry, C. M. [Yale Center for Astronomy and Astrophysics, 260 Whitney Avenue, New Haven, CT 06520 (United States); Elvis, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Salvato, M. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Brusa, M.; Lanzuisi, G.; Vignali, C. [Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy); Comastri, A.; Gilli, R.; Zamorani, G.; Cappelluti, N. [INAF—Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Hasinger, G. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States); Miyaji, T. [Instituto de Astronomía sede Ensenada, Universidad Nacional Autónoma de México, Km. 103, Carret. Tijunana-Ensenada, Ensenada, BC (Mexico); Treister, E. [Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción (Chile); Allevato, V.; Finoguenov, A. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland); Cardamone, C. [Department of Science, Wheelock College, Boston, MA 02215 (United States); Griffiths, R. E. [Physics and Astronomy Dept., Natural Sciences Division, University of Hawaii at Hilo, 200 W. Kawili Street, Hilo, HI 96720 (United States); Karim, A. [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, D-53121 Bonn (Germany); and others

    2016-01-20

    We present the catalog of optical and infrared counterparts of the Chandra  COSMOS-Legacy  Survey, a 4.6 Ms Chandra  program on the 2.2 deg{sup 2} of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the i, K, and 3.6 μm identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6 μm information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while ≃54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is available online. We study several X-ray to optical (X/O) properties: with our large statistics we put better constraints on the X/O flux ratio locus, finding a shift toward faint optical magnitudes in both soft and hard X-ray band. We confirm the existence of a correlation between X/O and the the 2–10 keV luminosity for Type 2 sources. We extend to low luminosities the analysis of the correlation between the fraction of obscured AGNs and the hard band luminosity, finding a different behavior between the optically and X-ray classified obscured fraction.

  12. Chandra Discovers "Rivers Of Gravity" That Define Cosmic Landscape

    Science.gov (United States)

    2002-07-01

    NASA’s Chandra X-ray Observatory has discovered part of an intergalactic web of hot gas and dark matter that contains most of the material in the universe. The hot gas, which appears to lie like a fog in channels carved by rivers of gravity, has been hidden from view since the time galaxies formed. “The Chandra observations, together with ultraviolet observations, are a major advance in our understanding of how the universe evolved over the last 10 billion years,” said Fabrizio Nicastro of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. and head of one of the teams of scientists involved in the discovery. Four independent teams of scientists, whose results appear as separate papers in The Astrophysical Journal, used Chandra to detect intergalactic gas with temperatures ranging from 300,000 to 5 million degrees Celsius. This gas forms part of a gigantic system of hot gas and dark matter that defines the cosmic landscape. The gaseous component alone contains more material than all the stars in the universe. “We had strong suspicions from the Big Bang theory and observations of the early universe that this gas exists in the present era, but like a stealth aircraft it had eluded our detection,” said Claude Canizares of the Massachusetts Institute of Technology (MIT), who along with Taotao Fang, led of one of the teams. The hot gas detected by Chandra can be used to trace the presence of the more massive dark matter component. The discovery of the hot gas may eventually enable astronomers to map of the distribution of dark matter in the universe and perhaps understand its origin. Ultraviolet telescopes had detected cooler components of the hot gas system, but because of its high temperatures most of it is detectable only with an extremely sensitive X-ray telescope. The various groups used two techniques to probe the intergalactic gas. One method uses the absorbing effects of the gas on X-rays from distant galaxies. On their way to

  13. NASA'S Chandra Finds Superfluid in Neutron Star's Core

    Science.gov (United States)

    2011-02-01

    NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star. Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities. Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons. The pressure in the star's core is so high that most of the charged particles, electrons and protons, merge resulting in a star composed mostly of uncharged particles called neutrons. Two independent research teams studied the supernova remnant Cassiopeia A, or Cas A for short, the remains of a massive star 11,000 light years away that would have appeared to explode about 330 years ago as observed from Earth. Chandra data found a rapid decline in the temperature of the ultra-dense neutron star that remained after the supernova, showing that it had cooled by about four percent over a 10-year period. "This drop in temperature, although it sounds small, was really dramatic and surprising to see," said Dany Page of the National Autonomous University in Mexico, leader of a team with a paper published in the February 25, 2011 issue of the journal Physical Review Letters. "This means that something unusual is happening within this neutron star." Superfluids containing charged particles are also superconductors, meaning they act as perfect electrical conductors and never lose energy. The new results strongly suggest that the remaining protons in the star's core are in a superfluid state and, because they carry a charge, also form a superconductor. "The rapid cooling in Cas A's neutron star, seen with Chandra, is the first direct evidence that the cores of these neutron stars are, in fact, made of superfluid and

  14. Chandra position of IGR J17454-2919 and discovery of a possible NIR counterpart

    DEFF Research Database (Denmark)

    Paizis, A.; Nowak, M.; Chati, S.

    2015-01-01

    On 2014 November 3, we observed the recently discovered INTEGRAL source IGR J17454-2919 (ATels #6530, #6574 and #6602) with Chandra HETGS for 20ks. The J2000.0 Chandra position we obtain is RA: 17 45 27.689 DEC: -29 19 53.83 (90% uncertainty of 0.6") This position (2.4" away from the Swift position...

  15. Chandra's Darkest Bright Star: not so Dark after All?

    Science.gov (United States)

    Ayres, Thomas R.

    2008-11-01

    The Chandra High Resolution camera (HRC) has obtained numerous short exposures of the ultraviolet (UV)-bright star Vega (α Lyrae; HD 172167: A0 V), to calibrate the response of the detector to out-of-band (non-X-ray) radiation. A new analysis uncovered a stronger "blue leak" in the imaging section (HRC-I) than reported in an earlier study of Vega based on a subset of the pointings. The higher count rate—a factor of nearly 2 above prelaunch estimates—raised the possibility that genuine coronal X-rays might lurk among the out-of-band events. Exploiting the broader point-spread function of the UV leak compared with soft X-rays identified an excess of counts centered on the target, technically at 3σ significance. A number of uncertainties, however, prevent a clear declaration of a Vegan corona. A more secure result would be within reach of a deep uninterrupted HRC-I pointing.

  16. The End of Days -- Chandra Catches X-ray Glow From Supernova

    Science.gov (United States)

    1999-12-01

    Through a combination of serendipity and skill, scientists have used NASA's Chandra X-ray Observatory to capture a rare glimpse of X-radiation from the early phases of a supernova, one of the most violent events in nature. Although more than a thousand supernovas have been observed by optical astronomers, the early X-ray glow from the explosions has been detected in less than a dozen cases. The Chandra observations were made under the direction of a team of scientists from the Massachusetts Institute of Technology (MIT) in Cambridge, led by Walter Lewin and his graduate student, Derek Fox. When combined with simultaneous observations by radio and optical telescopes, the X-ray observations tell about the thickness of the shell that was blown off, its density, its speed, and how much material was shed by the star before it exploded. Chandra observed an X-ray glow from SN1999em with the total power of 50,000 suns. Ten days later it observed the supernova for another nine hours, and found that the X rays had faded to half their previous intensity. The optical luminosity, which had the brightness of 200 million suns, had faded somewhat less. No radio emission was detected at any time. With this information, the MIT group and their colleagues are already piecing together a picture of the catastrophic explosion. Observations by optical astronomers showed that SN1999em was a Type II supernova produced by the collapse of the core of a star ten or more times as massive as the Sun. The intense heat generated in the collapse produces a cataclysmic rebound that sends high speed debris flying outward at speeds in excess of 20 million miles per hour. The debris crashes into matter shed by the former star before the explosion. This awesome collision generates shock waves that heat expanding debris to three million degrees. The X-ray glow from this hot gas was detected by Chandra and gives astrophysicists a better understanding of the dynamics of the explosion, as well as the

  17. AGN Activity in Nucleated Galaxies as Measured by Chandra

    Science.gov (United States)

    Foord, Adi; Gallo, Elena; Hodges-Kluck, Edmund; Miller, Brendan P.; Baldassare, Vivienne F.; Gültekin, Kayhan; Gnedin, Oleg Y.

    2017-05-01

    Motivated by theoretical expectations that nuclear star clusters (NSCs) in galactic centers may provide a favorable environment for supermassive black holes to form and/or efficiently grow, we set out to measure the fraction of nearby nucleated galaxies that also host an active galactic nucleus. We targeted a distance-limited sample of 98 objects with the Chandra X-ray Telescope, down to a uniform X-ray luminosity threshold of ˜1038 erg s-1. The sample is composed of 47 late-types and 51 early-types, enabling us to further investigate the active fraction as a function of galactic morphology. After correcting for contamination to the nuclear X-ray signal from bright X-ray binaries, we measure an active fraction f=11.2{ % }-4.9+7.4 (1σ C.L.) across the whole sample, in agreement with previous estimates based on a heterogeneous combination of optical, X-ray, and radio diagnostics, by Seth et al. After accounting for the different stellar mass distributions in our samples, we find no statistically significant difference in the active fraction of early- versus late-type nucleated galaxies, with f=10.6{ % }-4.9+11.9 and 10.8{ % }-6.3+11.3, respectively. For the early-type nucleated galaxies, we are able to carry out a controlled comparison with a parent sample of non-nucleated galaxies covering the same stellar mass range, again finding no statistically significant difference in the active fraction. Taken at face value, our findings suggest that the presence of an NSC does not facilitate or enhance accretion-powered emission from a nuclear supermassive black hole. This is true even for late-type nucleated galaxies, home to bluer NSCs and arguably larger gas reservoirs.

  18. Chandra ACIS Observations of Jovian X-Ray Emission

    Science.gov (United States)

    Garmire, Gordon; Elsner, Ronald; Feigelson, Eric; Ford, Peter; Gladstone, G. Randall; Hurley, Kevin; Metzger, Albert; Waite, J. Hunter, Jr.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    On November 25 and 26, 1999, the Chandra X-ray spacecraft conducted a set of four 19,000 sec observations of Jupiter. The ACIS-S instrument configuration was used for its good low energy efficiency and spatial resolution. An anomalous response was obtained which was subsequently attributed to strong jovian infrared radiation penetrating the detector and piling up spurious events across the entire X-ray range. However, the pre-observation establishment of an offsetting bias field has allowed the recovery of data from that portion of Jupiter's disc which remained within the elevated portion of the bias field during the observation. This ranges from fewer than 3000 sec to the entire observing time for about 10% of the planet. Auroral emission is seen near both poles in each observation. The northern aurora ia overall more intense than the southern, consistent with prior Einstein and ROSAT Observatory results. The southern aurora shows more modulation with Jupiter's rotation than the northern. Spatial resolution has been improved by at least a factor of two over prior measurements but convincing evidence of structure has not been seen. Lower latitude emission, first observed by ROSAT, is confirmed with flux levels averaging more than a factor of five below peak auroral values. Pronounced variation in the observed emission has occurred over the observing period. The spectral response extends from 0.24 keV, below which noise dominates, to about 1.2 keV. For all four observations the spectrum is clearly enhanced between 0.45 and 0.85 keV. This is apparently unequivocal evidence that Jupiter's X-ray emission is the result of oxygen and perhaps sulfur ions precipitating into the planet's atmosphere, where they undergo charge exchange interactions. The identification of specific transitions lines in the spectrum is among the ongoing efforts. A bremsstrahlung component has not yet been identified.

  19. Six Years Into Its Mission, NASA's Chandra X-ray Observatory Continues to Achieve Scientific Firsts

    Science.gov (United States)

    2005-08-01

    In August 1999, NASA's Chandra X-ray Observatory opened for business. Six years later, it continues to achieve scientific firsts. "When Chandra opened its sunshade doors for the first time, it opened the possibility of studying the X-ray emission of the universe with unprecedented clarity," said Chandra project scientist Dr. Martin Weisskopf of NASA's Marshall Space Flight Center in Huntsville, Ala. "Already surpassing its goal of a five-year life, Chandra continues to rewrite textbooks with discoveries about our own solar system and images of celestial objects as far as billions of light years away." Based on the observatory's outstanding results, NASA Headquarters in Washington decided in 2001 to extend Chandra s mission from five years to ten. During the observatory s sixth year of operation, auroras from Jupiter, X-rays from Saturn, and the early days of our solar system were the focus of Chandra discoveries close to home -- discoveries with the potential to better understand the dynamics of life on Earth. Jupiter's auroras are the most spectacular and active auroras in the solar system. Extended Chandra observations revealed that Jupiter s auroral X-rays are caused by highly charged particles crashing into the atmosphere above Jupiter's poles. These results gave scientists information needed to compare Jupiter's auroras with those from Earth, and determine if they are triggered by different cosmic and planetary events. Mysterious X-rays from Saturn also received attention, as Chandra completed the first observation of a solar X-ray flare reflected from Saturn's low-latitudes, the region that correlates to Earth's equator and tropics. This observation led scientists to conclude the ringed planet may act as a mirror, reflecting explosive activity from the sun. Solar-storm watchers on Earth might see a surprising benefit. The results imply scientists could use giant planets like Saturn as remote-sensing tools to help monitor X-ray flaring on portions of the sun

  20. Managing radiation degradation of CCDs on the Chandra X-ray Observatory II

    Science.gov (United States)

    O'Dell, Stephen L.; Aldcroft, Thomas L.; Bissell, Bradley A.; Blackwell, William C.; Cameron, Robert A.; Chappell, Jon II.; DePasquale, Joseph M.; Gage, Kenneth R.; Grant, Catherine E.; Harbison, Christine F.

    2005-01-01

    The CCDs on the Chandra X-ray Observatory are vulnerable to radiation damage from low-energy protons scattered off the telescope's mirrors onto the focal plane. Following unexpected damage incurred early in the mission, the Chandra Team developed, implemented, and maintains a radiation-protection program. This program - involving scheduled radiation safing during radiation-belt passes, intervention based upon real-time space-weather conditions and radiation-environment modeling, and on-board radiation monitoring with autonomous radiation safing - has successfully managed the radiation damage to the CCDs. Since implementing the program, the charge-transfer inefficiency (CTI) has increased at an average annual rate of only 2.9x10^-6 (2.3%) for the front- illuminated CCDs and 0.95x10^-6 (6.5%) for the back-illuminated CCDs. This paper describes the current status of Chandra radiation-management program.

  1. The Role of Project Science in the Chandra X-Ray Observatory

    Science.gov (United States)

    O'Dell, Stephen L.; Weisskopf, Martin C.

    2006-01-01

    The Chandra X-Ray Observatory, one of NASA's Great Observatories, has an outstanding record of scientific and technical success. This success results from the efforts of a team comprising NASA, its contractors, the Smithsonian Astrophysical Observatory, the instrument groups, and other elements of the scientific community, including thousands of scientists who utilize this powerful facility for astrophysical research. We discuss the role of NASA Project Science in the formulation, development, calibration, and operation of the Chandra X-ray Observatory. In addition to representing the scientific community within the Project, Project Science performed what we term "science systems engineering". This activity encompasses translation of science requirements into technical requirements and assessment of the scientific impact of programmatic and technical trades. We briefly describe several examples of science systems engineering conducted by Chandra Project Science.

  2. Chandra Observations of Dying Radio Sources in Galaxy Clusters

    Science.gov (United States)

    Murgia, M.; Markevitch, M.; Govoni, F.; Parma, P.; Fanti, R.; de Ruiter, H. R.; Mack, K.-H.

    2012-01-01

    Context. The dying radio sources represent a very interesting and largely unexplored stage of the active galactic nucleus (AGN) evolution. They are considered to be very rare, and almost all of the few known ones were found in galaxy clusters. However, considering the small number detected so far, it has not been possible to draw any firm conclusions about their X-ray environment. Aims. We present X-ray observations performed with the Chandra satellite of the three galaxy clusters Abell 2276, ZwCl 1829.3+6912, and RX J1852.1+5711, which harbor at their center a dying radio source with an ultra-steep spectrum that we recently discovered. Methods. We analyzed the physical properties of the X-ray emitting gas surrounding these elusive radio sources. We determined the global X-ray properties of the clusters, derived the azimuthally averaged profiles of metal abundance, gas temperature, density, and pressure. Furthermore, we estimated the total mass profiles. Results. The large-scale X-ray emission is regular and spherical, suggesting a relaxed state for these systems. Indeed, we found that the three clusters are also characterized by significant enhancements in the metal abundance and declining temperature profiles toward the central region. For all these reasons, we classified RX J1852.1+5711, Abell 2276, and ZwCl 1829.3+6912 as cool-core galaxy clusters. Conclusions. We calculated the non-thermal pressure of the radio lobes assuming that the radio sources are in the minimum energy condition. For all dying sources we found that this is on average about one to two orders of magnitude lower than that of the external gas, as found for many other radio sources at the center of galaxy groups and clusters. We found marginal evidence for the presence of X-ray surface brightness depressions coincident with the fossil radio lobes of the dying sources in A2276 and ZwCl 1829.3+691. We estimated the outburst age and energy output for these two dying sources. The energy power from

  3. Recovering galaxy cluster gas density profiles with XMM-Newton and Chandra

    Science.gov (United States)

    Bartalucci, I.; Arnaud, M.; Pratt, G. W.; Vikhlinin, A.; Pointecouteau, E.; Forman, W. R.; Jones, C.; Mazzotta, P.; Andrade-Santos, F.

    2017-12-01

    We examined the reconstruction of galaxy cluster radial density profiles obtained from Chandra and XMM-Newton X-ray observations, using high quality data for a sample of twelve objects covering a range of morphologies and redshifts. By comparing the results obtained from the two observatories and by varying key aspects of the analysis procedure, we examined the impact of instrumental effects and of differences in the methodology used in the recovery of the density profiles. We find that the final density profile shape is particularly robust. We adapted the photon weighting vignetting correction method developed for XMM-Newton for use with Chandra data, and confirm that the resulting Chandra profiles are consistent with those corrected a posteriori for vignetting effects. Profiles obtained from direct deprojection and those derived using parametric models are consistent at the 1% level. At radii larger than 6″, the agreement between Chandra and XMM-Newton is better than 1%, confirming an excellent understanding of the XMM-Newton PSF. Furthermore, we find no significant energy dependence. The impact of the well-known offset between Chandra and XMM-Newton gas temperature determinations on the density profiles is found to be negligible. However, we find an overall normalisation offset in density profiles of the order of 2.5%, which is linked to absolute flux cross-calibration issues. As a final result, the weighted ratios of Chandra to XMM-Newton gas masses computed at R2500 and R500 are r = 1.03 ± 0.01 and r = 1.03 ± 0.03, respectively. Our study confirms that the radial density profiles are robustly recovered, and that any differences between Chandra and XMM-Newton can be constrained to the 2.5% level, regardless of the exact data analysis details. These encouraging results open the way for the true combination of X-ray observations of galaxy clusters, fully leveraging the high resolution of Chandra and the high throughput of XMM-Newton.

  4. THE CHANDRA SURVEY OF EXTRAGALACTIC SOURCES IN THE 3CR CATALOG: X-RAY EMISSION FROM NUCLEI, JETS, AND HOTSPOTS IN THE CHANDRA ARCHIVAL OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F. [Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino (Italy); Harris, D. E.; Paggi, A.; Wilkes, B. J.; Kuraszkiewicz, J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Liuzzo, E.; Orienti, M.; Paladino, R. [Istituto di Radioastronomia, INAF, via Gobetti 101, I-40129, Bologna (Italy); Tremblay, G. R. [Yale Center for Astronomy and Astrophysics, Physics Department, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Baum, S. A.; O’Dea, C. P. [University of Manitoba, Dept of Physics and Astronomy, Winnipeg, MB R3T 2N2 (Canada)

    2015-09-15

    As part of our program to build a complete radio and X-ray database of all Third Cambridge catalog extragalactic radio sources, we present an analysis of 93 sources for which Chandra archival data are available. Most of these sources have already been published. Here we provide a uniform re-analysis and present nuclear X-ray fluxes and X-ray emission associated with radio jet knots and hotspots using both publicly available radio images and new radio images that have been constructed from data available in the Very Large Array archive. For about 1/3 of the sources in the selected sample, a comparison between the Chandra and radio observations was not reported in the literature: we find X-ray detections of 2 new radio jet knots and 17 hotspots. We also report the X-ray detection of extended emission from the intergalactic medium for 15 galaxy clusters.

  5. Chandra and HST Studies of the X-Ray Sources in Galactic Globular Cluster M92

    NARCIS (Netherlands)

    Lu, T.-N.; Kong, A.K.H.; Verbunt, F.W.M.|info:eu-repo/dai/nl/068970374; Lewin, W.H.G.; Anderson, S.F.; Pooley, D.

    2011-01-01

    We present the analysis of two observations of M92 taken with the Chandra X-Ray Observatory. We combined the two data sets with a total exposure of ∼52 ks. With the combined observation, we detected 10 X-ray sources inside the half-mass radius (1. 02), five of which are inside the core radius (0.

  6. Chandra and Hubble Space Telescope Study of the Globular Cluster NGC 288

    NARCIS (Netherlands)

    Kong, A.K.H.; Bassa, C.G.; Pooley, D.; Levin, W.H.G.; Homer, L.; Verbunt, F.W.M.|info:eu-repo/dai/nl/068970374; Anderson, S.F.; Margon, B.

    2006-01-01

    We report on the Chandra X-Ray Observatory observations of the globular cluster NGC 288.We detect four X-ray sources within the core radius and seven additional sources within the half-mass radius down to a limiting luminosity of LX ¼ 7 ; 1030 ergs s 1 (assuming cluster membership) in the 0.3Y7 keV

  7. Spying on millisecond pulsar paradise: Chandra+GBT monitoring of M28

    Science.gov (United States)

    Linares, Manuel

    2014-09-01

    We propose a coordinated Chandra and GBT program to monitor the millisecond pulsar population in the globular cluster M28, with a special focus on the unique transitional pulsar discovered last year. This unprecedented multi-wavelength campaign on a carefully selected cluster will bring us closer to understand how recycled pulsars are formed and how they interact with their surroundings.

  8. Deep Chandra observations of TeV binaries : I. LSI+61°303

    NARCIS (Netherlands)

    Rea, N.; Torres, D. F.; van der Klis, M.; Jonker, P.G.; Mendez, M.; Sierpowska-Bartosik, A.

    2010-01-01

    We report on a 95 ks Chandra observation of the TeV emitting high-mass X-ray binary LS I +61 degrees 303, using the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. The observation was performed while the compact object was passing from phase 0.94 to

  9. Deep Chandra observations of TeV binaries : II. LS 5039

    NARCIS (Netherlands)

    Rea, N.; Torres, D. F.; Caliandro, G. A.; Hadasch, D.; van der Klis, M.; Mendez, M.; Sierpowska-Bartosik, A.; Jonker, P.G.

    We report on Chandra observations of the TeV-emitting high-mass X-ray binary LS 5039, for a total exposure of similar to 70 ks, using the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. We did not find any periodic or quasi-periodic signal in the

  10. Chandra and XMM–Newton Observations of H 2 O Maser Galaxy ...

    Indian Academy of Sciences (India)

    For H2O megamaser galaxy Mrk 266, its Chandra and XMM–Newton data are analyzed here. It shows existence of two obscured nuclei (separation is ∼ 5''). Our preferred model, the high energy reflected model can fit the hard component of both nuclei spectra well.

  11. Chandra observations of comet 9P/Tempel 1 during the Deep Impact campaign

    NARCIS (Netherlands)

    Lisse, C. M.; Dennerl, K.; Christian, D. J.; Wolk, S. J.; Bodewits, D.; Zurbuchen, T. H.; Hansen, K. C.; Hoekstra, R.; Combi, M.; Fry, C. D.; Dryer, M.; Maekinen, T.; Sun, W.; Jansen, K.C.; Mäkinen, T.

    2007-01-01

    We present results from the Chandra X-ray Observatory's extensive campaign studying Comet 9P/Tempel 1 (T1) in support of NASA's Deep Impact (DI) mission. T1 was observed for similar to 295 ks between 30th June and 24th July 2005, and continuously for similar to 64 ks on July 4th during the impact

  12. Chandra X-ray Observations of 12 Millisecond Pulsars in the Globular Cluster M28

    NARCIS (Netherlands)

    Bogdanov, S.; van den Berg, M.C.; Servillat, M.; Heinke, C.O.; Grindlay, J.E.; Stairs, I.H.; Ransom, s.m.; Freire, P.C.C.; Bégin, S.; Becker, W.

    2011-01-01

    We present a Chandra X-ray Observatory investigation of the millisecond pulsars in the globular cluster M28 (NGC 6626). In what is one of the deepest X-ray observations of a globular cluster, we firmly detect seven and possibly detect two of the 12 known M28 pulsars. With the exception of PSRs

  13. The Chandra ACIS Timing Survey Project: glimpsing a sample of faint X-ray pulsators

    Science.gov (United States)

    Israel, G. L.; Esposito, P.; Rodríguez Castillo, G. A.; Sidoli, L.

    2016-11-01

    We report on the discovery of 41 new pulsating sources in the data of the Chandra Advanced CCD Imaging Spectrometer, which is sensitive to X-ray photons in the 0.3-10 keV band. The archival data of the first 15 yr of Chandra observations were retrieved and analysed by means of fast Fourier transforms, employing a peak-detection algorithm able to screen candidate signals in an automatic fashion. We carried out the search for new X-ray pulsators in light curves with more than 50 photons, for a total of about 190 000 light curves out of about 430 000 extracted. With these numbers, the ChAndra Timing Survey at Brera And Roma astronomical observatories (CATS @ BAR) - as we called the project - represents the largest ever systematic search for coherent signals in the classic X-ray band. More than 50 per cent of the signals were confirmed by further Chandra (for those sources with two or more pointings), XMM-Newton or ROSAT data. The period distribution of the new X-ray pulsators above ˜2000 s resembles that of cataclysmic variables, while there is a paucity of sources with shorter period and low fluxes. Since there is not an obvious bias against these detections, a possible interpretation is in terms of a magnetic gating mechanism in accreting neutron stars. Finally, we note that CATS @ BAR is a living project and the detection algorithm will continue to be routinely applied to the new Chandra data as they become public. Based on the results obtained so far, we expect to discover about three new pulsators every year.

  14. A Deep Chandra X-Ray Study of Neutron Star Coalescence GW170817

    Science.gov (United States)

    Haggard, Daryl; Nynka, Melania; Ruan, John J.; Kalogera, Vicky; Cenko, S. Bradley; Evans, Phil; Kennea, Jamie A.

    2017-10-01

    We report Chandra observations of GW170817, the first neutron star–neutron star merger discovered by the joint LIGO-Virgo Collaboration, and the first direct detection of gravitational radiation associated with an electromagnetic counterpart, Fermi short γ-ray burst GRB 170817A. The event occurred on 2017 August 17 and subsequent observations identified an optical counterpart, SSS17a, coincident with NGC 4993 (∼10″ separation). Early Chandra ({{Δ }}t∼ 2 days) and Swift ({{Δ }}t∼ 1{--}3 days) observations yielded non-detections at the optical position, but ∼9 days post-trigger Chandra monitoring revealed an X-ray point source coincident with SSS17a. We present two deep Chandra observations totaling ∼95 ks, collected on 2017 September 01–02 ({{Δ }}t∼ 15{--}16 days). We detect X-ray emission from SSS17a with {L}0.3{--10{keV}}={2.6}-0.4+0.5× {10}38 erg s‑1, and a power law spectrum of {{Γ }}=2.4+/- 0.8. We find that the X-ray light curve from a binary NS coalescence associated with this source is consistent with the afterglow from an off-axis short γ-ray burst, with a jet angled ≳23° from the line of sight. This event marks both the first electromagnetic counterpart to a LIGO-Virgo gravitational-wave source and the first identification of an off-axis short GRB. We also confirm extended X-ray emission from NGC 4993 ({L}0.3{--10{keV}}∼ 9× {10}38 erg s‑1) consistent with its E/S0 galaxy classification, and report two new Chandra point sources in this field, CXOU J130948 and CXOU J130946.

  15. Chandra Resolves Cosmic X-ray Glow and Finds Mysterious New Sources

    Science.gov (United States)

    2000-01-01

    While taking a giant leap towards solving one of the greatest mysteries of X-ray astronomy, NASA's Chandra X-ray Observatory also may have revealed the most distant objects ever seen in the universe and discovered two puzzling new types of cosmic objects. Not bad for being on the job only five months. Chandra has resolved most of the X-ray background, a pervasive glow of X-rays throughout the universe, first discovered in the early days of space exploration. Before now, scientists have not been able to discern the background's origin, because no X-ray telescope until Chandra has had both the angular resolution and sensitivity to resolve it. "This is a major discovery," said Dr. Alan Bunner, Director of NASA's Structure andEvolution of the universe science theme. "Since it was first observed thirty-seven years ago, understanding the source of the X-ray background has been aHoly Grail of X-ray astronomy. Now, it is within reach." The results of the observation will be discussed today at the 195th national meeting of the American Astronomical Society in Atlanta, Georgia. An article describing this work has been submitted to the journal Nature by Dr. Richard Mushotzky, of NASA Goddard Space Flight Center, Greenbelt, Md., Drs. Lennox Cowie and Amy Barger at the University of Hawaii, Honolulu, and Dr. Keith Arnaud of the University of Maryland, College Park. "We are all very excited by this finding," said Mushotzky. "The resolution of most of the hard X-ray background during the first few months of the Chandra mission is a tribute to the power of this observatory and bodes extremely well for its scientific future," Scientists have known about the X-ray glow, called the X-ray background, since the dawn of X-ray astronomy in the early 1960s. They have been unable to discern its origin, however, for no X-ray telescope until Chandra has had both the angular resolution and sensitivity to resolve it. The German-led ROSAT mission, now completed, resolved much of the lower

  16. Chandra Discovers X-Ray Ring Around Cosmic Powerhouse in Crab Nebula

    Science.gov (United States)

    1999-09-01

    After barely two months in space, NASA's Chandra X-ray Observatory has taken a stunning image of the Crab Nebula, the spectacular remains of a stellar explosion, and has revealed something never seen before: a brilliant ring around the nebula's heart. Combined with observations from the Hubble Space Telescope, the image provides important clues to the puzzle of how the cosmic "generator," a pulsing neutron star, energizes the nebula, which still glows brightly almost 1,000 years after the explosion. "The inner ring is unique," said Professor Jeff Hester of Arizona State University, Tempe, AZ. "It has never been seen before, and it should tell us a lot about how the energy from the pulsar gets into the nebula. It's like finding the transmission lines between the power plant and the light bulb." Professor Mal Ruderman of Columbia University, New York, NY, agreed. "The X-rays Chandra sees are the best tracer of where the energy is. With images such as these, we can directly diagnose what is going on." What is going on, according to Dr. Martin Weisskopf, Chandra Project Scientist from NASA's Marshall Space Flight Center, Huntsville, AL, is awesome. "The Crab pulsar is accelerating particles up to the speed of light and flinging them out into interstellar space at an incredible rate." The image shows tilted rings or waves of high-energy particles that appear to have been flung outward over the distance of a light year from the central star, and high-energy jets of particles blasting away from the neutron star in a direction perpendicular to the spiral. Hubble Space Telescope images have shown moving knots and wisps around the neutron star, and previous X-ray images have shown the outer parts of the jet and hinted at the ring structure. With Chandra's exceptional resolution, the jet can be traced all the way in to the neutron star, and the ring pattern clearly appears. The image was made with Chandra's Advanced CCD Imaging Spectrometer and High Energy Transmission

  17. Jet Power and Black Hole Assortment Revealed in New Chandra Image

    Science.gov (United States)

    2008-01-01

    A dramatic new Chandra image of the nearby galaxy Centaurus A provides one of the best views to date of the effects of an active supermassive black hole. Opposing jets of high-energy particles can be seen extending to the outer reaches of the galaxy, and numerous smaller black holes in binary star systems are also visible. The image was made from an ultra-deep look at the galaxy Centaurus A, equivalent to more than seven days of continuous observations. Centaurus A is the nearest galaxy to Earth that contains a supermassive black hole actively powering a jet. X-ray Image of Centaurus A, Labeled X-ray Image of Centaurus A, Labeled A prominent X-ray jet extending for 13,000 light years points to the upper left in the image, with a shorter "counterjet" aimed in the opposite direction. Astronomers think that such jets are important vehicles for transporting energy from the black hole to the much larger dimensions of a galaxy, and affecting the rate at which stars form there. High-energy electrons spiraling around magnetic field lines produce the X-ray emission from the jet and counterjet. This emission quickly saps the energy from the electrons, so they must be continually reaccelerated or the X-rays will fade out. Knot-like features in the jets detected in the Chandra image show where the acceleration of particles to high energies is currently occurring, and provides important clues to understanding the process that accelerates the electrons to near-light speeds. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Chandra Data Reveal Rapidly Whirling Black Holes Erratic Black Hole Regulates Itself The inner part of the X-ray jet close to the black hole is dominated by these knots of X-ray emission, which probably come from shock waves -- akin to sonic booms -- caused by the jet. Farther from the black hole there is more diffuse X-ray emission in the jet. The cause of particle

  18. Modeling Contamination Migration on the Chandra X-ray Observatory II

    Science.gov (United States)

    O'Dell, Steve; Swartz, Doug; Tice, Neil; Plucinsky, Paul; Grant, Catherine; Marshall, Herman; Vikhlinin, Alexey

    2013-01-01

    During its first 14 years of operation, the cold (about -60degC) optical blocking filter of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination that attenuates low-energy x rays. Over the past few years, the accumulation rate, spatial distribution, and composition may have changed, perhaps partially related to changes in the operating temperature of the ACIS housing. This evolution of the accumulation of the molecular contamination has motivated further analysis of contamination migration on the Chandra X-ray Observatory, particularly within and near the ACIS cavity. To this end, the current study employs a higher-fidelity geometric model of the ACIS cavity, detailed thermal modeling based upon monitored temperature data, and an accordingly refined model of the molecular transport.

  19. Joint XMM-Newton, Chandra, and RXTE Observations of Cyg X-1 at Phase Zero

    Science.gov (United States)

    Pottschmidt, Katja

    2008-01-01

    We present first results of simultaneous observations of the high mass X-ray binary Cyg X-1 for 50 ks with XMM-Newton, Chandra-HETGS and RXTE in 2008 April. The observations are centered on phase 0 of the 5.6 d orbit when pronounced dips in the X-ray emission from the black hole are known to occur. The dips are due to highly variable absorption in the accretion stream from the O-star companion to the black hole. Compared to previous high resolution spectroscopy studies of the dip and non-dip emission with Chandra, the addition of XMM-Newton data allows for a better determination of the continuum, especially through the broad iron line region (with RXTE constraining the greater than 10 keV continuum).

  20. Impacts of Chandra X-ray Observatory Education and Public Outreach

    Science.gov (United States)

    Lestition, K.; Arcand, K.; Watzke, M.

    2014-07-01

    The overarching goal of Chandra's multifaceted communications and public engagement (EPO) program is to open access for anyone to be a learner and explorer of the Universe. To achieve this goal, the Chandra EPO team develops products and activities that share new discoveries about the Universe with diverse audiences, engages the imaginations of students, teachers, and the general public, and increases learning opportunities. We partner with organizations such as the National Science Olympiad, the 4-H, the NASA Museum Alliance, and the American Library Association to leverage their distribution networks for national impact. We summarize the results of a sample of wide-reaching, synthesized suite of programs—ranging from press, to outreach, to informal and formal education—that communicate the compelling topics that only the high-energy Universe can reveal.

  1. Using ACIS on the Chandra X-ray Observatory as a Particle Radiation Monitor II

    Science.gov (United States)

    Grant, C. E.; Ford, P. G.; Bautz, M. W.; ODell, S. L.

    2012-01-01

    The Advanced CCD Imaging Spectrometer is an instrument on the Chandra X-ray Observatory. CCDs are vulnerable to radiation damage, particularly by soft protons in the radiation belts and solar storms. The Chandra team has implemented procedures to protect ACIS during high-radiation events including autonomous protection triggered by an on-board radiation monitor. Elevated temperatures have reduced the effectiveness of the on-board monitor. The ACIS team has developed an algorithm which uses data from the CCDs themselves to detect periods of high radiation and a flight software patch to apply this algorithm is currently active on-board the instrument. In this paper, we explore the ACIS response to particle radiation through comparisons to a number of external measures of the radiation environment. We hope to better understand the efficiency of the algorithm as a function of the flux and spectrum of the particles and the time-profile of the radiation event.

  2. Observations of the Crab Nebula with the Chandra X-Ray Observatory

    Science.gov (United States)

    Weisskopf, Martin C.

    2012-01-01

    The Crab Nebula and its pulsar has been the subject of a number of detailed observations with the Chandra X-ray Observatory. The superb angular resolution of Chandra s high-resolution telescope has made possible numerous remarkable results. Here we describe a number of specific studies of the Crab that I and my colleagues have undertaken. We discuss the geometry of the system, which indicates that the "inner X-ray ring", typically identified with the termination shock of the pulsar s particle wind, is most likely not in the equatorial plane of the pulsar. Other topics are the northern wisps and their evolution with time; the characterization of features in the jet to the southeast; pulse-phase spectroscopy and possible correlations with the features at other wavelengths, particularly the optical polarization; and a search for correlations of the X-ray flux with the recently-discovered gamma -ray flares.

  3. Chandra's Cosmos: Dark Matter, Black Holes, and Other Wonders Revealed by NASA's Premier X-ray Observatory

    Science.gov (United States)

    Tucker, Wallace H.

    2017-03-01

    On July 23, 1999, the Chandra X-Ray Observatory, the most powerful X-ray telescope ever built, was launched aboard the space shuttle Columbia. Since then, Chandra has given us a view of the universe that is largely hidden from telescopes sensitive only to visible light. In Chandra's Cosmos, the Smithsonian Astrophysical Observatory's Chandra science spokesperson Wallace H. Tucker uses a series of short, connected stories to describe the telescope's exploration of the hot, high-energy face of the universe. The book is organized in three parts: "The Big," covering the cosmic web, dark energy, dark matter, and massive clusters of galaxies; "The Bad," exploring neutron stars, stellar black holes, and supermassive black holes; and "The Beautiful," discussing stars, exoplanets, and life. Chandra has imaged the spectacular, glowing remains of exploded stars and taken spectra showing the dispersal of their elements. Chandra has observed the region around the supermassive black hole in the center of our Milky Way and traced the separation of dark matter from normal matter in the collision of galaxies, contributing to both dark matter and dark energy studies. Tucker explores the implications of these observations in an entertaining, informative narrative aimed at space buffs and general readers alike.

  4. Deep Chandra observations of TeV binaries I : LS I+61 303

    NARCIS (Netherlands)

    Rea, N.; Torres, D.F.; Klis, M. van der; Mendez, M.; Sierpowska-Bartosik, A.; Jonker, P.G.

    2010-01-01

    We report on a 95 ks Chandra observation of the TeV emitting High Mass X– ray Binary LS I+61303, using the ACIS-S camera in Continuos Clocking mode to search for a possible X-ray pulsar in this system. The observation was performed while the compact object was passing from phase 0.94 to 0.98 in its

  5. Deep Chandra observations of TeV binaries - II. LS 5039

    NARCIS (Netherlands)

    Rea, N.; Torres, D. F.; Caliandro, G. A.; Hadasch, D.; van der Klis, M.; Jonker, P. G.; Méndez, M.; Sierpowska-Bartosik, A.

    We report on Chandra observations of the TeV-emitting high-mass X-ray binary LS 5039 , for a total exposure of ˜70 ks, using the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. We did not find any periodic or quasi-periodic signal in the 0.3-0.4 and

  6. Deep Chandra observations of TeV binaries - I. LS I +61°303

    NARCIS (Netherlands)

    Rea, N.; Torres, D.F.; van der Klis, M.; Jonker, P.G.; Méndez, M.; Sierpowska-Bartosik, A.

    2010-01-01

    We report on a 95 ks Chandra observation of the TeV emitting high-mass X-ray binary LS I +61°303, using the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. The observation was performed while the compact object was passing from phase 0.94 to 0.98 in

  7. Deep Chandra observations of TeV binaries - I. LSI+61°303

    NARCIS (Netherlands)

    Rea, N.; Torres, D. F.; van der Klis, M.; Jonker, P. G.; Méndez, M.; Sierpowska-Bartosik, A.

    We report on a 95ks Chandra observation of the TeV emitting high-mass X-ray binary LSI+61°303, using the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. The observation was performed while the compact object was passing from phase 0.94 to 0.98 in its

  8. Deep Chandra observations of TeV binaries - II. LS 5039

    NARCIS (Netherlands)

    Rea, N.; Torres, D.F.; Caliandro, G.A.; Hadasch, D.; van der Klis, M.; Jonker, P.G.; Mendez, R.M.; Sierpowska-Bartosik, A.

    2011-01-01

    We report on Chandra observations of the TeV-emitting high-mass X-ray binary LS 5039 , for a total exposure of ∼70 ks, using the ACIS-S camera in continuous clocking mode to search for a possible X-ray pulsar in this system. We did not find any periodic or quasi-periodic signal in the 0.3-0.4 and

  9. Rapport de frais de 2017-2018 pour Chandra Madramootoo | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Rapport de frais de 2017-2018 pour Chandra Madramootoo. Total des frais de déplacement : CAD$10,021.68. Constatation de l'impact de la recherche en Afrique de l'Est. 4 juillet 2017 au 11 juillet 2017. CAD$8,095.97. Réunion du Conseil des gouverneurs. 20 juin 2017 au 21 juin 2017. CAD$1,925.71. Ce que nous ...

  10. Chandra and XMM–Newton Observations of H2O Maser Galaxy Mrk ...

    Indian Academy of Sciences (India)

    component, another power-law ( = 2.45 ± 0.07) for the soft component and a narrow Gaussian fitted to the Fe Kα line (EW∼48 eV) (see Fig. 2). The common model for Seyfert 2 and the above models cannot be well-fitted with the Chandra spectra. Residuals in terms of sigma show significant excess in 2–4 KeV and over 8 ...

  11. Chandra Observations of the Nuclei of Radio Galaxies: 3C 295 and Hydra A

    Science.gov (United States)

    Harris, D. E.; McNamara, B. R.; David, L. P.; Lavoie, Anthony R. (Technical Monitor)

    2000-01-01

    The angular resolution available with Chandra allows us to isolate the X-ray emission from the nucleus of many radio galaxies and obtain their spectra. As expected from unification schemes, spectra so far obtained can best be interpreted as heavily absorbed power laws. We present the spectral parameters so derived for 3C 295 and Hydra A and compare them to data obtained at other wavelengths.

  12. Real Time Space Weather Support for Chandra X-Ray Observatory Operations

    Science.gov (United States)

    O'Dell, Stephen L.; Minow, Joseph I.; Miller, J. Scott; Wolk, Scott J.; Aldcroft, Thomas L.; Spitzbart, Bradley D.; Swartz. Douglas A.

    2012-01-01

    NASA launched the Chandra X-ray Observatory in July 1999. Soon after first light in August 1999, however, degradation in the energy resolution and charge transfer efficiency of the Advanced CCD Imaging Spectrometer (ACIS) x-ray detectors was observed. The source of the degradation was quickly identified as radiation damage in the charge-transfer channel of the front-illuminated CCDs, by weakly penetrating ( soft , 100 500 keV) protons as Chandra passed through the Earth s radiation belts and ring currents. As soft protons were not considered a risk to spacecraft health before launch, the only on-board radiation monitoring system is the Electron, Proton, and Helium Instrument (EPHIN) which was included on Chandra with the primary purpose of monitoring energetic solar particle events. Further damage to the ACIS detector has been successfully mitigated through a combination of careful mission planning, autonomous on-board radiation protection, and manual intervention based upon real-time monitoring of the soft-proton environment. The AE-8 and AP-8 trapped radiation models and Chandra Radiation Models are used to schedule science operations in regions of low proton flux. EPHIN has been used as the primary autonomous in-situ radiation trigger; but, it is not sensitive to the soft protons that damage the front-illuminated CCDs. Monitoring of near-real-time space weather data sources provides critical information on the proton environment outside the Earth s magnetosphere due to solar proton events and other phenomena. The operations team uses data from the Geostationary Operational Environmental Satellites (GOES) to provide near-real-time monitoring of the proton environment; however, these data do not give a representative measure of the soft-proton (strategies to minimize the proton damage in the ACIS CCD detectors and the importance of real-time data sources that are used to protect the ACIS detector system from space weather events.

  13. Using XMM and Chandra to probe the mass distribution in the most distant massive galaxy clusters

    Science.gov (United States)

    Bartalucci, I.

    2017-10-01

    We present a detailed study of the mass profiles of the five most massive clusters detected at z˜1 via the Sunyaev-Zel'dovich effect. These objects represent an ideal laboratory to test our models in a mass regime where structure formation is driven mainly by gravity. We present a method to study these objects that optimally exploits information from XMM-Newton and Chandra observations. The combination of Chandra's excellent spatial resolution and XMM-Newton's photon collecting power allows us to investigate the properties of the hydrostatic mass profile from the core to the outskirts, for the first time in such objects. We contrast the optical and X-ray mass estimates by comparing our results with recently-published HST lensing values. Evolution properties are also investigated by comparison with the REXCESS local galaxy cluster sample. Finally, we discuss the current limitations of this method in the context of joint analysis of future Chandra and XMM large programs and, more generally, of multi-wavelength efforts to study high redshift objects.

  14. NASA's Chandra Finds That Saturn Reflects X-rays From Sun

    Science.gov (United States)

    2005-05-01

    When it comes to mysterious X-rays from Saturn, the ringed planet may act as a mirror, reflecting explosive activity from the sun, according to scientists using NASA's Chandra X-ray Observatory. The findings stem from the first observation of an X-ray flare reflected from Saturn's low-latitudes - the region that correlates to Earth's equator and tropics. Led by Dr. Anil Bhardwaj, a planetary scientist at NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., the study revealed that Saturn acts as a diffuse mirror for solar X-rays. Counting photons - particles that carry electromagnetic energy including X-rays - was critical to this discovery. For every few thousand X-ray photons Saturn receives from the sun, it reflects a single X-ray photon back. Previous studies revealed that Jupiter, with a diameter 11 times that of Earth, behaves in a similar fashion. Saturn is about 9.5 times as big as Earth, but is twice as far from Earth as Jupiter. "The bigger the planet and nearer to the Sun, the more solar photons it will intercept - resulting in more reflected X-rays," said Bhardwaj. "These results imply we could use giant planets like Jupiter and Saturn as remote-sensing tools. By reflecting solar activity back to us, they could help us monitor X-ray flaring on portions of the sun facing away from Earth's space satellites." Massive solar explosions called flares often accompany coronal mass ejections, which emit solar material and magnetic field. When directed toward the Earth, these ejections can wreak havoc on communication systems from cell phones to satellites. Even as the research appears to have solved one mystery - the source of Saturn's X-rays, it fueled longstanding questions about magnetic fields. Earth's magnetic field is the reason compasses work, since the field acts like a huge bar magnet, causing the magnetic north pole of a compass to point to the magnetic south pole of the Earth. In addition, migratory birds seem to sense the magnetic field

  15. THE CHANDRA LOCAL VOLUME SURVEY: THE X-RAY POINT-SOURCE CATALOG OF NGC 300

    Energy Technology Data Exchange (ETDEWEB)

    Binder, B.; Williams, B. F.; Dalcanton, J. J.; Anderson, S. F.; Weisz, D. R. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Eracleous, M. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Gaetz, T. J.; Plucinsky, P. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Cambridge, MA 02138 (United States); Skillman, E. D. [Astronomy Department, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2012-10-10

    We present the source catalog of a new Chandra ACIS-I observation of NGC 300 obtained as part of the Chandra Local Volume Survey. Our 63 ks exposure covers {approx}88% of the D{sub 25} isophote (R Almost-Equal-To 6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance to a limiting unabsorbed 0.35-8 keV luminosity of {approx}10{sup 36} erg s{sup -1}. Sources were cross-correlated with a previous XMM-Newton catalog, and we find 75 'X-ray transient candidate' sources that were detected by one observatory, but not the other. We derive an X-ray scale length of 1.7 {+-} 0.2 kpc and a recent star formation rate of 0.12 M{sub Sun} yr{sup -1} in excellent agreement with optical observations. Deep, multi-color imaging from the Hubble Space Telescope, covering {approx}32% of our Chandra field, was used to search for optical counterparts to the X-ray sources, and we have developed a new source classification scheme to determine which sources are likely X-ray binaries, supernova remnants, and background active galactic nucleus candidates. Finally, we present the X-ray luminosity functions (XLFs) at different X-ray energies, and we find the total NGC 300 X-ray point-source population to be consistent with other late-type galaxies hosting young stellar populations ({approx}< 50 Myr). We find that XLF of sources associated with older stellar populations has a steeper slope than the XLF of X-ray sources coinciding with young stellar populations, consistent with theoretical predictions.

  16. A CHANDRA OBSERVATION OF THE ECLIPSING WOLF-RAYET BINARY CQ Cep

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Stephen L. [CASA, Univ. of Colorado, Boulder, CO 80309-0389 (United States); Zhekov, Svetozar A. [Space Research and Technology Institute, Akad. G. Bonchev Str., Sofia, 1113 (Bulgaria); Güdel, Manuel [Dept. of Astrophysics, Univ. of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria); Schmutz, Werner, E-mail: stephen.skinner@colorado.edu, E-mail: szhekov@space.bas.bg, E-mail: manuel.guedel@univie.ac.at, E-mail: werner.schmutz@pmodwrc.ch [Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Dorfstrasse 33, CH-7260 Davos Dorf (Switzerland)

    2015-02-01

    The short-period (1.64 d) near-contact eclipsing WN6+O9 binary system CQ Cep provides an ideal laboratory for testing the predictions of X-ray colliding wind shock theory at close separation where the winds may not have reached terminal speeds before colliding. We present results of a Chandra X-ray observation of CQ Cep spanning ∼1 day during which a simultaneous Chandra optical light curve was acquired. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T ≳ 20 MK) will form on or near the line-of-centers between the stars. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ∼ 4-40 MK. A deep optical eclipse was seen as the O star passed in front of the Wolf-Rayet star and we determine an orbital period P {sub orb} = 1.6412400 d. Somewhat surprisingly, no significant X-ray variability was detected. This implies that the hottest X-ray plasma is not confined to the region between the stars, at odds with the colliding wind picture and suggesting that other X-ray production mechanisms may be at work. Hydrodynamic simulations that account for such effects as radiative cooling and orbital motion will be needed to determine if the new Chandra results can be reconciled with the colliding wind picture.

  17. Deep Chandra Survey of the Small Magellanic Cloud. II. Timing Analysis of X-Ray Pulsars

    Science.gov (United States)

    Hong, JaeSub; Antoniou, Vallia; Zezas, Andreas; Haberl, Frank; Sasaki, Manami; Drake, Jeremy J.; Plucinsky, Paul P.; Laycock, Silas

    2017-09-01

    We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg2 region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb-Scargle and epoch-folding techniques, we detected periodic modulations from 20 pulsars and a new candidate pulsar. The survey also covered 11 other pulsars with no clear sign of periodic modulation. The 0.5-8 keV X-ray luminosity (L X ) of the pulsars ranges from 1034 to 1037 erg s-1 at 60 kpc. All of the Chandra sources with L X ≳ 4 × 1035 erg s-1 exhibit X-ray pulsations. The X-ray spectra of the SMC pulsars (and high-mass X-ray binaries) are in general harder than those of the SMC field population. All but SXP 8.02 can be fitted by an absorbed power-law model with a photon index of Γ ≲ 1.5. The X-ray spectrum of the known magnetar SXP 8.02 is better fitted with a two-temperature blackbody model. Newly measured pulsation periods of SXP 51.0, SXP 214, and SXP 701, are significantly different from the previous XMM-Newton and RXTE measurements. This survey provides a rich data set for energy-dependent pulse profile modeling. Six pulsars show an almost eclipse-like dip in the pulse profile. Phase-resolved spectral analysis reveals diverse spectral variations during pulsation cycles: e.g., for an absorbed power-law model, some exhibit an (anti)-correlation between absorption and X-ray flux, while others show more intrinsic spectral variation (I.e., changes in photon indices).

  18. Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

    Energy Technology Data Exchange (ETDEWEB)

    Van Weeren, R. J.; Jones, C.; Forman, W. R.; Andrade-Santos, F.; Pearce, Connor J. J.; David, L.; Kraft, R. P.; Nulsen, P. E. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ogrean, G. A. [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States); Bonafede, A.; Brüggen, M. [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany); Bulbul, E. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Clarke, T. E. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375 (United States); Churazov, E. [Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany); Dawson, W. A. [Lawrence Livermore National Lab, 7000 East Avenue, Livermore, CA 94550 (United States); Donahue, M. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Goulding, A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Mason, B. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Merten, J. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Mroczkowski, T., E-mail: rvanweeren@cfa.harvard.edu [ESO—European Organization for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Str. 2, D-85748 Garching b. München (Germany); and others

    2017-02-01

    To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeast of this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100–300 kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleus lead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for re-acceleration (revival) of fossil electrons. The presence of hot ≳20 keV ICM gas detected by Chandra near the relic location provides additional support for this re-acceleration scenario.

  19. Infrared Faint Radio Sources in the Extended Chandra Deep Field South

    Science.gov (United States)

    Huynh, Minh T.

    2009-01-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey (ATLAS) which have no observable counterpart in the Spitzer Wide-area Infrared Extragalactic Survey (SWIRE). The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6 to 70 micron) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the SED of these objects shows that they are consistent with high redshift AGN (z > 2).

  20. Chandra and XMM–Newton Observations of H2O Maser Galaxy Mrk ...

    Indian Academy of Sciences (India)

    For its relative lower resolution (∼ 6 ), XMM–Newton. 16:20.0. 8:20.0. 19.0. 18.0 ... can not resolve these two nucleus. It also shows the extended ... Chandra and XMM–Newton Observations. 181. 10. 0.01. 2×10 3. 5×10 3. 0.02 normaliz ed counts s. 1 ke. V. 1. 0.5. 1. 1.5. 2. 2.5. 0. 5×10 3. 0.01 residuals. Energy (keV). (c). 10.

  1. Chandra Mukerji, Impossible Engineering : Technology and Territoriality on the Canal du Midi

    OpenAIRE

    M. W. Ertsen

    2012-01-01

    Chandra Mukerji nous propose un ouvrage important sur la conception et la construction du Canal du Midi, appelé Canal royal du Languedoc sous l’Ancien Régime. Ce canal exceptionnel fut en effet construit durant le règne de Louis XIV, en parallèle avec les travaux de Versailles. Ce fut le plus vaste chantier de génie civil de son temps et il formait alors le plus grand canal jamais construit dans le monde occidental. Ce livre est important pour une série de raisons. La première est qu’il a tou...

  2. Modeling Contamination Migration on the Chandra X-ray Observatory - II

    Science.gov (United States)

    O'Dell, Stephen L.; Swartz, Douglas A.; Tice, Neil W.; Plucinsky, Paul P.; Grant, Catherine E.; Marshall, Herman L.; Vikhlinin, Alexey A.; Tennant, Allyn F.

    2013-01-01

    During its first 14 years of operation, the cold (about -60C) optical blocking filter of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination that attenuates low-energy x rays. Over the past few years, the accumulation rate, spatial distribution, and composition have changed. This evolution has motivated further analysis of contamination migration within and near the ACIS cavity. To this end, the current study employs a higher-fidelity geometric model of the ACIS cavity, detailed thermal modeling based upon temperature data, and a refined model of the molecular transport.

  3. Modeling Contamination Migration on the Chandra X-Ray Observatory - III

    Science.gov (United States)

    O'Dell, Stephen L.; Swartz, Douglas A.; Tice, Neil W.; Plucinsky, Paul P.; Grant, Catherine E.; Marshall, Herman L.; Vikhlinin, Alexy A.; Tennant, Allyn F.; Dahmer, Matthew T.

    2015-01-01

    During its first 16 years of operation, the cold (about -60 C) optical blocking filter of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination that attenuates low-energy x rays. Over the past few years, the accumulation rate, spatial distribution, and composition have changed. This evolution has motivated further analysis of contamination migration within and near the ACIS cavity, in part to evaluate potential bake-out scenarios intended to reduce the level of contamination. Keywords: X-ray astronomy, CCDs, contamination, modeling and simulation, spacecraft operations

  4. Chandra Helps Put The Pieces Together On Gamma-Ray Bursts

    Science.gov (United States)

    2000-11-01

    NASA’s Chandra X-ray Observatory has detected never-before-seen properties in the X-ray afterglow of a gamma-ray burst. This discovery strengthens the case for a “hypernova” model, where massive collapsed stars generate these mysterious blasts of high-energy radiation believed to be the most powerful explosions in the universe. An international team of scientists used Chandra to observe iron emission lines from ejected material surrounding the gamma-ray burst (GRB) known as GRB991216. This is the first time emission lines associated with GRBs have been unambiguously detected and their properties precisely measured at X-ray wavelengths. Astronomers have long debated how GRBs originate. One theory contends that GRBs result when two “compact objects,” that is, neutron stars or black holes, collide and coalesce. Another theory speculates that a “hypernova,” a gigantic star collapsing on itself under its own weight, could cause these extremely energetic outbursts. “The discovery of iron lines in the X-ray spectrum is an important clue to our understanding of GRBs,” said Luigi Piro, lead author of the paper that appeared in the November 3 issue of the journal Science. “Studying the immediate area around the GRB tells us a great deal about the origin of the GRB itself.” A shift in the wavelength, or energy, of the detected iron line emission (relative to what would be seen in a laboratory) tells the researchers the distance to the GRB. The Chandra team determined that it has taken roughly 8 billion years for the X rays from GRB991216 to reach the Earth, in agreement with an independent estimate from an absorption feature in the optical light from the host galaxy. From the distance and the intensities of the detected X-ray emission lines, the investigators deduced the properties of the ejected material and its relationship to the GRB. The team was able to determine the mass of the medium within a light day or two of the GRB as approximately equivalent

  5. Chandra Observes Cosmic Traffic Pile-Up In Energetic Quasar Jet

    Science.gov (United States)

    2000-11-01

    Using the unrivaled high resolution of NASA's Chandra X-ray Observatory, astronomers have seen important new details in the powerful jet shooting from the quasar 3C273. This research, coupled with optical and radio data, may reveal how these very high velocity jets are driven from the supermassive black holes that scientists believe lurk in the center of quasars. "For the first time, Chandra has given us an X-ray view into the area between 3C273's core and the beginning of the jet," says MIT's Herman Marshall, lead author on the paper submitted to Astrophysical Journal Letters. "Instead of being void of X-ray emission, Chandra has enabled us to detect a faint, but definite, stream of energy." The high-powered jets driven from quasars, often at velocities very close to the speed of light, have long been perplexing for scientists. Instead of seeing a smooth stream of material driven from the core of the quasar, most optical, radio, and earlier X-ray observations have revealed inconsistent, "lumpy" clouds of gas. This newly discovered continuous X-ray flow in 3C273 from the core to the jet may reveal insight on the physical processes that power these jets. Scientists would like to learn why matter is violently ejected from the quasar's core, then appears to suddenly slow down. "If there is a slower car in front on a highway, a faster one from behind will eventually catch up and maybe cause a wreck," says Marshall. "If the jet flow velocity changes, then gas shocks may result, which are akin to car collisions. These gigantic clouds of high-energy electrons, now seen in X rays with Chandra, may indeed be the result of some sort of cosmic traffic pile-up." The X-ray power produced in one of these pile-ups is tremendous. For example, the X-ray output of the first knot in the jet is greater than that of most Seyfert galaxies, which are thought to be powered by supermassive black holes. The abundance of X-ray emission suggests that large amounts of energy may also be

  6. M Stars in the TW Hydra Association: A Chandra Large Program Survey

    Science.gov (United States)

    Punzi, Kristina; Kastner, Joel; Principe, David; Stelzer, Beate; Gorti, Uma; Pascucci, Illaria; Argiroffi, Costanza

    2018-01-01

    We have conducted a Cycle 18 Chandra Large Program survey of very cool members of the $\\sim$ 8 Myr-old TW Hydra Association (TWA) to extend our previous study of the potential connections between M star disks and X-rays (Kastner et al. 2016, AJ, 152, 3) to the extreme low-mass end of the stellar initial mass function. The spectral types of our targets extend down to the M/L borderline. Thus we can further investigate the potential connection between the intense X-ray emission from young, low-mass stars and the lifetimes of their circumstellar planet-forming discs, as well as better constrain the age at which coronal activity declines for stellar masses approaching the H-burning limit of $\\sim$ 0.08 M$_{\\odot}$. We present preliminary results from the Cycle 18 survey, including X-ray detection statistics and measurements of relative X-ray luminosities and coronal (X-ray) temperatures for those TWA stars detected by Chandra. This research is supported by SAO/CXC grant GO7-18002A and NASA Astrophysics Data Analysis program grants NNX12AH37G and NNX16AG13G to RIT.

  7. Future prospects with the Chandra and XMM source catalogs: Setting the stage for Lynx

    Science.gov (United States)

    Hickox, Ryan C.

    2018-01-01

    Lynx is a NASA concept X-ray mission that will probe the distant Universe to extremely faint fluxes and with superb angular resolution. I will discuss how the Chandra and XMM X-ray source catalogs will enable important progress on our understanding of AGN populations and will inform the preparations for the Lynx survey program. The wide areas covered by these serendipitous surveys enable a census of the X-ray Universe that includes low-luminosity AGN such as low-Eddington and dwarf systems, as well as rare sources such as super-Eddington AGN and mergers. Characterizing these AGN provides a view of the populations that, at high redshifts, will be uniquely detected and characterized with Lynx. The XMM and Chandra source catalogs also provide important constraints on the evolution of the quasar luminosity function, allowing more accurate predictions for the number of lower-luminosity, high redshift sources that may be detected with Lynx as it probes the formation of black holes in the early Universe.

  8. Anatomy of a Merger: A Deep Chandra Observation of Abell 115

    Science.gov (United States)

    Forman, William R.

    2017-08-01

    A deep Chandra observation of Abell 115 provides a unique probe of the anatomy of cluster mergers. The X-ray image shows two prominent subclusters, A115N (north) and A115S (south) with a projected separation of almost 1 Mpc. The X-ray subclusters each have ram-pressure stripped tails that unambiguously indicate the directions of motion. The central BCG of A115N hosts the radio source 3C28 which shows a pair of jets, almost perpendicular to the direction of the sucluster's motion. The jets terminate in lobes each of which has a "tail" pointing IN the direction of motion of the subcluster. The Chandra analysis provides details of the merger including the velocities of the subclusters both through analysis of the cold front and a weak shock. The motion of A115N through the cluster generates counter-rotating vortices in the subcluster gas that form the two radio tails. Hydrodynamic modeling yields circulation velocities within the A115N sub cluster. Thus, the radio emitting plasma acts as a dye tracing the motions of the X-ray emitting plasma. A115S shows two "cores", one coincident with the BCG and a second appears as a ram pressure stripped tail.

  9. Monitoring the Chandra X-ray Observatory via the Wireless Internet

    Science.gov (United States)

    Spitzbart, B. D.; Wolk, S. J.; Cameron, R. A.

    The Chandra X-ray Observatory, launched in July 1999, continues to provide unprecedented high energy astrophysical discoveries with efficiency and reliability. From time to time, though, urgent operational decisions must be made by engineers, instrument teams, and scientists, often on short notice and at odd hours. There are several real-time, mostly Internet-based data resources available to aid in the decision-making discussions when a crisis arises. Chandra's Science Operations Team (SOT) has been experimenting with emerging Wireless Application Protocol (WAP) technologies to create yet another pathway for data flow. Our WAP Internet pages provide anytime, anywhere access to critical spacecraft information through cellular phones or other WAP-enabled devices. There are, of course, many challenges in attempting to present useful, meaningful content on a 5 × 12 character screen over limited bandwidth in a way that is user-friendly and beneficial. This paper will discuss our experience with this developing and promising new medium, design strategies, and future enhancements.

  10. High School Students Discover Neutron Star Using Chandra and VLA Data

    Science.gov (United States)

    2000-12-01

    Three high school students, using data from NASA's Chandra X-ray Observatory and the National Science Foundation's Very Large Array (VLA), have found the first evidence of a neutron star in the nearby supernova remnant IC443, a system long studied by professional astronomers. This remarkable discovery has led the team to the national finals and a 1st place finish in the team competition at the Siemens-Westinghouse Science and Technology Competition held today in Washington, DC. Charles Olbert (age 18), Christopher Clearfield (age 18), and Nikolas Williams (age 16), all of the North Carolina School for Science and Mathematics (NCSSM) in Durham, NC, found a point-like source of X rays embedded in the remains of the stellar explosion, or supernova. Based on both the X-ray and radio data, the students determined that the central object in IC443 is most likely a young and rapidly rotating neutron star -- an object known as a "pulsar." "This is a really solid scientific finding," said Bryan Gaensler of the Massachusetts Institute of Technology, a noted pulsar expert who reviewed the paper for the team. "Everyone involved should be really proud of this accomplishment." Taking advantage of Chandra's superior angular resolution, the North Carolina students found the source embedded in IC443, a region known to be emitting particularly high-energy X rays. In a highly unusual situation, the students got access to the Chandra data from their science teacher, Dr. Jonathan Keohane. Keohane applied for the observation time while still associated with NASA's Goddard Space Flight Center. "The students really went through the whole analysis process themselves," said Keohane. "And, they even lived together all summer near the school to complete the research." In order to confirm the evidence from Chandra, the students turned to the National Radio Observatory's Dale Frail who gave the student team VLA data on IC443. While the radio data did not reveal any periodicity, the VLA

  11. A Statistical Approach to Galaxy Cluster Gas Inhomogeneity: Chandra Observations of Nearby Galaxy Clusters

    Science.gov (United States)

    Reese, Erik D.; Kawahara, H.; Kitayama, T.; Sasaki, S.; Suto, Y.

    2009-01-01

    Motivated by cosmological hydrodynamic simulations, the intracluster medium (ICM) inhomogeneity of galaxy clusters is modeled statistically with a lognormal model for density inhomogeneity. Through mock observations of synthetic clusters the relationship between density inhomogeneities and that of the X-ray surface brightness has been developed. This enables one to infer the statistical properties of the fluctuations of the underlying three-dimensional density distribution of real galaxy clusters from X-ray observations. We explore inhomogeneity in the intracluster medium by applying the above methodology to Chandra observations of a sample of nearby galaxy clusters. We also consider extensions of the model, including Poissonian effects and compare this hybrid lognormal-Poisson model to the nearby cluster Chandra data. EDR gratefully acknowledges support from JSPS (Japan Society for the Promotion of Science) Postdoctoral Fellowhip for Foreign Researchers award P07030. HK is supported by Grands-in-Aid for JSPS of Science Fellows. This work is also supported by Grant-in-Aid for Scientific research of Japanese Ministry of Education, Culture, Sports, Science and Technology (Nos. 20.10466, 19.07030, 16340053, 20340041, and 20540235) and by JSPS Core-to-Core Program "International Research Network for Dark Energy".

  12. Chandra's Observations of Jupiter's X-Ray Aurora During Juno Upstream and Apojove Intervals

    Science.gov (United States)

    Jackman, C.M.; Dunn, W.; Kraft, R.; Gladstone, R.; Branduardi-Raymont, G.; Knigge, C.; Altamirano, D.; Elsner, R.

    2017-01-01

    The Chandra space telescope has recently conducted a number of campaigns to observe Jupiter's X-ray aurora. The first set of campaigns took place in summer 2016 while the Juno spacecraft was upstream of the planet sampling the solar wind. The second set of campaigns took place in February, June and August 2017 at times when the Juno spacecraft was at apojove (expected close to the magnetopause). We report on these upstream and apojove campaigns including intensities and periodicities of auroral X-ray emissions. This new era of jovian X-ray astronomy means we have more data than ever before, long observing windows (up to 72 kiloseconds for this Chandra set), and successive observations relatively closely spaced in time. These features combine to allow us to pursue novel methods for examining periodicities in the X-ray emission. Our work will explore significance testing of emerging periodicities, and the search for coherence in X-ray pulsing over weeks and months, seeking to understand the robustness and regularity of previously reported hot spot X-ray emissions. The periods that emerge from our analysis will be compared against those which emerge from radio and UV wavelengths.

  13. The X-ray high resolution Chandra spectra of Nova SMC 2016

    Science.gov (United States)

    Orio, Marina; Aydi, Elias; Behar, Ehud; Buckley, David; Dobrotka, Andrej; Ness, Jan-Uwe; Page, Kim L.; Rauch, Thomas; Zemko, Polina

    2017-08-01

    Nova SMC 2016 was discovered in the direction of the SMC by the MASTER Global Robotic Net on 2016 October 14. At peak optical magnitude B~9.55, if it is located in the SMC it is one of the intrinsically most luminous novae ever recorded. The X-ray to optical luminosity of the nova is around the average value, so it was also very X-ray luminous for a nova in the SMC. It was classified as a fast nova. It was monitored with Swift until the present day (2017 May), with close cadence whenever it was feasible, and we were able to observe it on the rise to maximum X-ray luminosity on 2016 November 17-18 and at maximum on 2017 January 4 with the Chandra Low Energy Transmission Grating (another high resolution X-ray spectrum was obtained with XMM-Newton on 2016 December 22). We report on the luminous supersoft spectrum of the central source observed with Chandra, a luminous stellar continuum with effective temperature of about 650,000 K in December and 750,000 K in January, with deep absorption features of carbon, nitrogen and sulphur, blue-shifted by about 1700 km/s in November and by 2100 km/s in January. We describe the results of our initial spectral and timing analysis.

  14. The Northern Rims of SNR RCW 86 Chandras Recent Observations and their Implications for Particle Acceleration

    Science.gov (United States)

    Castro, Daniel

    2018-01-01

    The Chandra observations towards the northwest (NW) and northeast (NE) rims of supernova remnant (SNR) RCW 86 reveal great detail about the characteristics of the shocks, particle acceleration and the local environments in these 2 distinct regions. Both the NW and NE of RCW 86 show clear evidence of non-thermal X-ray emission, identified as synchrotron radiation from shock-accelerated electrons with TeV energies, interacting with the compressed, and probably amplified, local magnetic field.Magnetic field amplification (MFA) is broadly believed to result from, and contribute to, cosmic ray acceleration at the shocks of SNRs. However, we still lack a detailed understanding of the particle acceleration mechanism, and with this study we address the connection between the shock properties and ambient medium with MFA. The Chandra observations of RCW 86 allowed us to constrain the magnitude of the post- shock magnetic field in the NE and NW rims by deriving synchrotron filament widths, and also the densities in these regions, using thermal emission co-located with the non-thermal rims. I will discuss our analysis in detail and comment on how MFA appears to be related to certain characteristics of the SNR shock.

  15. The Northern Rims of SNR RCW 86 - Chandra's Recent Observations and their Implications for Particle Acceleration

    Science.gov (United States)

    Castro, Daniel

    2017-08-01

    The Chandra observations towards the northwest (NW) and northeast (NE) rims of supernova remnant (SNR) RCW 86 reveal great detail about the characteristics of the shocks, particle acceleration and the local environments in these 2 distinct regions. Both the NW and NE of RCW 86 show clear evidence of non-thermal X-ray emission, identified as synchrotron radiation from shock-accelerated electrons with TeV energies, interacting with the compressed, and probably amplified, local magnetic field. Magnetic field amplification (MFA) is broadly believed to result from, and contribute to, cosmic ray acceleration at the shocks of SNRs. However, we still lack a detailed understanding of the particle acceleration mechanism, and with this study we address the connection between the shock properties and ambient medium with MFA. The Chandra observations of RCW 86 allowed us to constrain the magnitude of the post-shock magnetic field in the NE and NW rims by deriving synchrotron filament widths, and also the densities in these regions, using thermal emission co-located with the non-thermal rims. I will discuss our analysis in detail and comment on how MFA appears to be related to certain characteristics of the SNR shock.

  16. Monitoring of the Crab Nebula with Chandra and Other Observatories Including HST

    Science.gov (United States)

    Weisskopf, Martin C.

    2014-01-01

    Subsequent to the detections AGILE and Fermi/LAT of the gamma-ray flares from the Crab Nebula in the fall of 2010, this team has been monitoring the X-Ray emission from the Crab on a regular basis. X-Ray observations have taken place typically once per month when viewing constraints allow and more recently four times per year. There have been notable exceptions, e.g. in April of 2011 and March 2013 when we initiated a set of Chandra Target of opportunity observations in conjunction with bright gamma-ray flares. For much of the time regular HST observations were made in conjunction with the Chandra observations. The aim of this program to further characterize, in depth, the X-Ray and optical variations that take place in the nebula, and by so doing determine the regions which contribute to the harder X-ray variations and, if possible, determine the precise location within the Nebula of the origin of the gamma-ray flares. As part of this project members of the team have developed Singular Value Decomposition techniques to sequences of images in order to more accurately characterize features. The current status of the project will be presented highlighting studies of the inner knot and possible correlations with the flares.

  17. The software development process at the Chandra X-ray Center

    Science.gov (United States)

    Evans, Janet D.; Evans, Ian N.; Fabbiano, Giuseppina

    2008-08-01

    Software development for the Chandra X-ray Center Data System began in the mid 1990's, and the waterfall model of development was mandated by our documents. Although we initially tried this approach, we found that a process with elements of the spiral model worked better in our science-based environment. High-level science requirements are usually established by scientists, and provided to the software development group. We follow with review and refinement of those requirements prior to the design phase. Design reviews are conducted for substantial projects within the development team, and include scientists whenever appropriate. Development follows agreed upon schedules that include several internal releases of the task before completion. Feedback from science testing early in the process helps to identify and resolve misunderstandings present in the detailed requirements, and allows review of intangible requirements. The development process includes specific testing of requirements, developer and user documentation, and support after deployment to operations or to users. We discuss the process we follow at the Chandra X-ray Center (CXC) to develop software and support operations. We review the role of the science and development staff from conception to release of software, and some lessons learned from managing CXC software development for over a decade.

  18. Constraints on shock acceleration physics from the Chandra Large Project observations of SN 1006

    Science.gov (United States)

    Reynolds, Stephen; Katsuda, Satoru; Petre, Robert; Long, Knox S.; Winkler, P. Frank; Ressler, Sean; Williams, Brian

    The remnant of the supernova of 1006 C.E., the brightest historical supernova ever recorded, has provided a laboratory for the study of shock acceleration since the discovery and modeling of nonthermal X-rays over 30 years ago. It has now been observed with the Chandra X-ray Observatory for a total of over 1 Ms, including a full mapping of the remnant in 2012. Chandra's sub-arcsecond angular resolution has allowed detailed study of expansion proper motions, constraints on upstream precursor emission, and ``thin-rim" filamentary morphology at the remnant edges and its energy-dependence, among other properties. I shall summarize the observational data and their consequences for our understanding of the nature of fast shock waves and particle acceleration. The absence of clear upstream ``halo" emission requires that the shock precursor be very narrow, in turn implying amplification of magnetic field in the precursor. Rim thicknesses shrink rapidly with energy, confirming strong post-shock magnetic-field amplification and demanding surprisingly small diffusion coefficients downstream.

  19. A Chandra Study of Supernova Remnants in the Large and Small Magellanic Clouds

    Science.gov (United States)

    Schenck, Andrew Corey

    2017-08-01

    In the first part of this thesis we measure the interstellar abundances for the elements O, Ne, Mg, Si, and Fe in the Large Magellanic Cloud (LMC), based on the observational data of sixteen supernova remnants (SNRs) in the LMC as available in the public archive of the Chandra X-ray Observatory (Chandra). We find lower abundances than previous measurements based on a similar method using data obtained with the Advanced Satellite for Astrophysics and Cosmology (ASCA). We discuss the origins of the discrepancy between our Chandra and the previous ASCA measurements. We conclude that our measurements are generally more reliable than the ASCA results thanks to the high-resolution imaging spectroscopy with our Chandra data, although there remain some systematic uncertainties due to the use of different spectral modelings between the previous work and ours. We also discuss our results in comparison with the LMC abundance measurements based on optical observations of stars. The second part of this thesis is a detailed study of a core-collapse SNR B0049-73.6 in the Small Magellanic Cloud (SMC). Based on our deep Chandra observation, we detect metal-rich ejecta features extending out to the outermost boundary of B0049-73.6, which were not seen in the previous data. We find that the central nebula is dominated by emission from reverse-shocked ejecta material enriched in O, Ne, Mg, and Si. O-rich ejecta distribution is relatively smooth throughout the central nebula. In contrast the Si-rich material is highly structured. These results suggest that B0049-73.6 was produced by an asymmetric core-collapse explosion of a massive star. The estimated abundance ratios among these ejecta elements are in plausible agreement with the nucleosynthesis products from the explosion of a 13-15M. progenitor. We reveal that the central ring-like (in projection) ejecta nebula extends to ˜9 pc from the SNR center. This suggests that the contact discontinuity (CD) may be located at a further

  20. Overview of the configuration, technology challenges, and science capabilities for a successor to the Chandra X-ray Observatory

    Science.gov (United States)

    Vikhlinin, Alexey

    2014-08-01

    I will present a straw-man configuration for a future high-throughput, high angular resolution X-ray observatory which will be a true successor to Chandra. I will discuss the major technological challenges and the current approaches for overcoming those challenges. I will also discuss the science capabilities for this observatory.

  1. Simultaneous NuSTAR/Chandra Observations of The Bursting Pulsar GRO J1744-28 During Its Third Reactivation

    DEFF Research Database (Denmark)

    Younes, G.; Kouveliotou, C.; Grefenstette, B. W.

    2015-01-01

    We report on a 10 ks simultaneous Chandra/High Energy Transmission Grating (HETG)-Nuclear Spectroscopic Telescope Array (NuSTAR) observation of the Bursting Pulsar, GRO J1744-28, during its third detected outburst since discovery and after nearly 18 yr of quiescence. The source is detected up to 60...

  2. Nustar and Chandra insight into the nature of the 3-40 kev nuclear emission in NGC 253

    DEFF Research Database (Denmark)

    Lehmer, B. D.; Wik, D. R.; Hornschemeier, A. E.

    2013-01-01

    by an absorbed (NH ≈ 1.6 × 1023 cm-2) broken power-law model with spectral slopes and break energies that are typical of ultraluminous X-ray sources (ULXs), but not active galactic nuclei (AGNs). A previous Chandra observation in 2003 showed a hard X-ray point source of similar luminosity to the 2012 source...

  3. X-Ray Spectroscopy of Optically Bright Planets using the Chandra Observatory

    Science.gov (United States)

    Ford, P. G.; Elsner, R. F.

    2005-01-01

    Since its launch in July 1999, Chandra's Advanced CCD Imaging Spectrometer (ACIS) has observed several planets (Venus, Mars, Jupiter and Saturn) and 6 comets. At 0.5 arc-second spatial resolution, ACIS detects individual x-ray photons with good quantum efficiency (25% at 0.6 KeV) and energy resolution (20% FWHM at 0.6 KeV). However, the ACIS CCDs are also sensitive to optical and near-infrared light, which is absorbed by optical blocking filters (OBFs) that eliminate optical contamination from all but the brightest extended sources, e.g., planets. .Jupiter at opposition subseconds approx.45 arc-seconds (90 CCD pixels.) Since Chandra is incapable of tracking a moving target, the planet takes 10 - 20 kiloseconds to move across the most sensitive ACIS CCD, after which the observatory must be re-pointed. Meanwhile, the OBF covering that CCD adds an opt,ical signal equivalent to approx.110 eV to each pixel that lies within thc outline of the Jovian disk. This has three consequences: (1) the observatory must be pointed away from Jupiter while CCD bias maps are constructed; (2) most x-rays from within the optical image will be misidentified as charged-particle background and ignored; and (3) those x-rays that are reported will bc assigned anomalously high energies. The same also applies to thc other planets, but is less serious since they are either dimmer at optical wavelengths, or they show less apparent motion across the sky, permitting reduced CCD exposure times: the optical contamination from Saturn acids approx.15 eV per pixel, and from Mars and Venus approx.31 eV. After analyzing a series of short .Jupiter observations in December 2000, ACIS parameters were optimized for the February 2003 opposition. CCD bias maps were constructed while Chandra pointed away from Jupiter, and the subsequent observations employed on-board software to ignore any pixel that contained less charge than that expected from optical leakage. In addition, ACIS was commanded to report 5 x 5

  4. The Chandra planetary nebula survey (CHANPLANS). II. X-ray emission from compact planetary nebulae

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, M.; Kastner, J. H. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Montez, R. Jr. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Balick, B. [Department of Astronomy, University of Washington, Seattle, WA (United States); Frew, D. J.; De Marco, O.; Parker, Q. A. [Department of Physics and Astronomy and Macquarie Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109 (Australia); Jones, D. [Departamento de Física, Universidad de Atacama, Copayapu 485, Copiapó (Chile); Miszalski, B. [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Sahai, R. [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States); Blackman, E.; Frank, A. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Chu, Y.-H. [Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Guerrero, M. A. [Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, Granada, E-18008 (Spain); Lopez, J. A. [Instituto de Astronomía, Universidad Nacional Autonoma de Mexico, Campus Ensenada, Apdo. Postal 22860, Ensenada, B. C. (Mexico); Zijlstra, A. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Bujarrabal, V. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Corradi, R. L. M. [Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife (Spain); Nordhaus, J. [NSF Astronomy and Astrophysics Fellow, Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States); and others

    2014-10-20

    We present results from the most recent set of observations obtained as part of the Chandra X-ray observatory Planetary Nebula Survey (CHANPLANS), the first comprehensive X-ray survey of planetary nebulae (PNe) in the solar neighborhood (i.e., within ∼1.5 kpc of the Sun). The survey is designed to place constraints on the frequency of appearance and range of X-ray spectral characteristics of X-ray-emitting PN central stars and the evolutionary timescales of wind-shock-heated bubbles within PNe. CHANPLANS began with a combined Cycle 12 and archive Chandra survey of 35 PNe. CHANPLANS continued via a Chandra Cycle 14 Large Program which targeted all (24) remaining known compact (R {sub neb} ≲ 0.4 pc), young PNe that lie within ∼1.5 kpc. Results from these Cycle 14 observations include first-time X-ray detections of hot bubbles within NGC 1501, 3918, 6153, and 6369, and point sources in HbDs 1, NGC 6337, and Sp 1. The addition of the Cycle 14 results brings the overall CHANPLANS diffuse X-ray detection rate to ∼27% and the point source detection rate to ∼36%. It has become clearer that diffuse X-ray emission is associated with young (≲ 5 × 10{sup 3} yr), and likewise compact (R {sub neb} ≲ 0.15 pc), PNe with closed structures and high central electron densities (n{sub e} ≳ 1000 cm{sup –3}), and is rarely associated with PNe that show H{sub 2} emission and/or pronounced butterfly structures. Hb 5 is one such exception of a PN with a butterfly structure that hosts diffuse X-ray emission. Additionally, two of the five new diffuse X-ray detections (NGC 1501 and NGC 6369) host [WR]-type central stars, supporting the hypothesis that PNe with central stars of [WR]-type are likely to display diffuse X-ray emission.

  5. X-ray Variability In Extragalactic Jets as Seen by Chandra

    Science.gov (United States)

    Trevor, Max; Meyer, Eileen; Georganopoulos, Markos; Aubin, Sam; Hewitt, Jennifer; DeNigris, Natalie; Whitley, Kevin

    2018-01-01

    The unrivaled spatial resolution of Chandra has lead to the detection of over 100 extragalactic jetsemitting X-rays on kiloparsec scales, far from the central AGN. These jets are understood to be powerful redistributors of energy on galactic and extragalactic scales, with important effects on galaxy evolution and cluster heating. However, we lack an understanding of many important jet properties, including the particle makeup, particle acceleration characteristics, and total energy content, and even how fast the jet is at kpc scales. In the most powerful jets, a persistently open question is the nature of the emission mechanism for the Chandra-observed X-rays. While inverse Compton upscattering of CMB photons (IC/CMB) by a still-relativistic jet is widely adopted, our group has very recently ruled it out in several cases, suggesting that the X-rays from powerful sources, like the low-power jets, have a synchrotron origin, albeit one with unknown origins, requiring in-situ lepton acceleration at least up to 100 TeV. A very efficient way to extend this result to many more sources is to check for variability of the large scale jet X-ray emission, something that is definitively not expected in the case of IC/CMB due to the extremely long cooling times of the electrons responsible for the emission, but it is plausible if the X-rays are of synchrotron nature. Based on previously published observations of X-ray variability in the jets of M87 and Pictor A, as well as preliminary results suggesting variability in two more powerful jets, we have examined archival observations of over 40 jets which have been imaged twice or more with Chandra for variability, with timescales of a few to nearly 14 years. This analysis has two main goals, namely (i) to confirm a synchrotron origin for the X-rays in powerful sources, as variability is inconsistent with the competing IC/CMB model and (ii) to use the timescales and characteristics (e.g., spectral changes) of any detected X

  6. Nustar and Chandra Insight into the Nature of the 3-40 Kev Nuclear Emission in Ngc 253

    Science.gov (United States)

    Lehmer, Bret D.; Wik, Daniel R.; Hornschemeier, Ann E.; Ptak, Andrew; Antoniu, V.; Argo, M.K.; Bechtol, K.; Boggs, S.; Christensen, F.E.; Craig, W.W.; hide

    2013-01-01

    We present results from three nearly simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and Chandra monitoring observations between 2012 September 2 and 2012 November 16 of the local star-forming galaxy NGC 253. The 3-40 kiloelectron volt intensity of the inner approximately 20 arcsec (approximately 400 parsec) nuclear region, as measured by NuSTAR, varied by a factor of approximately 2 across the three monitoring observations. The Chandra data reveal that the nuclear region contains three bright X-ray sources, including a luminous (L (sub 2-10 kiloelectron volt) approximately few × 10 (exp 39) erg per s) point source located approximately 1 arcsec from the dynamical center of the galaxy (within the sigma 3 positional uncertainty of the dynamical center); this source drives the overall variability of the nuclear region at energies greater than or approximately equal to 3 kiloelectron volts. We make use of the variability to measure the spectra of this single hard X-ray source when it was in bright states. The spectra are well described by an absorbed (power-law model spectral fit value, N(sub H), approximately equal to 1.6 x 10 (exp 23) per square centimeter) broken power-law model with spectral slopes and break energies that are typical of ultraluminous X-ray sources (ULXs), but not active galactic nuclei (AGNs). A previous Chandra observation in 2003 showed a hard X-ray point source of similar luminosity to the 2012 source that was also near the dynamical center (Phi is approximately equal to 0.4 arcsec); however, this source was offset from the 2012 source position by approximately 1 arcsec. We show that the probability of the 2003 and 2012 hard X-ray sources being unrelated is much greater than 99.99% based on the Chandra spatial localizations. Interestingly, the Chandra spectrum of the 2003 source (3-8 kiloelectron volts) is shallower in slope than that of the 2012 hard X-ray source. Its proximity to the dynamical center and harder Chandra spectrum

  7. Chandra Discovers the X-ray Signature of a Powerful Wind from a Galactic Microquasar

    Science.gov (United States)

    2000-11-01

    NASA's Chandra X-ray Observatory has detected, for the first time in X rays, a stellar fingerprint known as a P Cygni profile--the distinctive spectral signature of a powerful wind produced by an object in space. The discovery reveals a 4.5-million-mile-per-hour wind coming from a highly compact pair of stars in our galaxy, report researchers from Penn State and the Massachusetts Institute of Technology in a paper they will present on 8 November 2000 during a meeting of the High-Energy Astrophysics Division of the American Astronomical Society in Honolulu, Hawaii. The paper also has been accepted for publication in The Astrophysical Journal Letters. "To our knowledge, these are the first P Cygni profiles reported in X rays," say researchers Niel Brandt, assistant professor of astronomy and astrophysics at Penn State, and Norbert S. Schulz, research scientist at the Massachusetts Institute of Technology. The team made the discovery during their first observation of a binary-star system with the Chandra X-ray Observatory, which was launched into space in July 1999. The system, known as Circinus X-1, is located about 20,000 light years from Earth in the constellation Circinus near the Southern Cross. It contains a super-dense neutron star in orbit around a normal fusion-burning star like our Sun. Although Circinus X-1 was discovered in 1971, many properties of this system remain mysterious because Circinus X-1 lies in the galactic plane where obscuring dust and gas have blocked its effective study in many wavelengths. The P Cygni spectral profile, previously detected primarily at ultraviolet and optical wavelengths but never before in X rays, is the textbook tool astronomers rely on for probing stellar winds. The profile looks like the outline of a roller coaster, with one really big hill and valley in the middle, on a data plot with velocity on one axis and the flow rate of photons per second on the other. It is named after the famous star P Cygni, in which such

  8. The O VII X-Ray Forest Toward Markarian 421: Consistency between XMM-Newton and Chandra

    Energy Technology Data Exchange (ETDEWEB)

    Kaastra, J.S.; Werner, N.; Herder, J.W.A.den; /SRON, Utrecht; Paerels, F.B.S.; /Columbia U., Astron. Astrophys.; de Plaa, J.; /SRON, Utrecht; Rasmussen, A.P.; /KIPAC, Menlo; de Vries, C.P.; /SRON, Utrecht

    2006-04-28

    Recently the first detections of highly ionized gas associated with two Warm-Hot Intergalactic Medium (WHIM) filaments have been reported. The evidence is based on X-ray absorption lines due to O VII and other ions observed by Chandra towards the bright blazar Mrk 421. We investigate the robustness of this detection by a re-analysis of the original Chandra LETGS spectra, the analysis of a large set of XMM-Newton RGS spectra of Mrk 421, and additional Chandra observations. We address the reliability of individual spectral features belonging to the absorption components, and assess the significance of the detection of these components. We also use Monte Carlo simulations of spectra. We confirm the apparent strength of several features in the Chandra spectra, but demonstrate that they are statistically not significant. This decreased significance is due to the number of redshift trials that are made and that are not taken into account in the original discovery paper. Therefore these features must be attributed to statistical fluctuations. This is confirmed by the RGS spectra, which have a higher signal to noise ratio than the Chandra spectra, but do not show features at the same wavelengths. Finally, we show that the possible association with a Ly{alpha} absorption system also lacks sufficient statistical evidence. We conclude that there is insufficient observational proof for the existence of the two proposed WHIM filaments towards Mrk 421, the brightest X-ray blazar on the sky. Therefore, the highly ionized component of the WHIM still remains to be discovered.

  9. Correlation Functions of Harish-Chandra Integrals over the Orthogonal and the Symplectic Groups

    Science.gov (United States)

    Prats Ferrer, A.; Eynard, B.; di Francesco, P.; Zuber, J.-B.

    2007-12-01

    The Harish-Chandra correlation functions, i.e. integrals over compact groups of invariant monomials prod operatorname{tr}(X^{p1}\\varOmega Y^{q1}\\varOmega^{dagger}X^{p2}\\cdots) with the weight exp tr ( X Ω Y Ω † ) are computed for the orthogonal and symplectic groups. We proceed in two steps. First, the integral over the compact group is recast into a Gaussian integral over strictly upper triangular complex matrices (with some additional symmetries), supplemented by a summation over the Weyl group. This result follows from the study of loop equations in an associated two-matrix integral and may be viewed as the adequate version of Duistermaat-Heckman's theorem for our correlation function integrals. Secondly, the Gaussian integration over triangular matrices is carried out and leads to compact determinantal expressions.

  10. Chandra Takes on Heavy Jets and Massive Winds in 4U 1630-47

    Science.gov (United States)

    Neilsen, Joey

    2014-11-01

    Recently, Díaz Trigo et al. reported the discovery of relativistic baryons in a jet in XMM/ATCA observations of the 2012 outburst of the black hole 4U 1630-47. We present a search for a similarly massive jet earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. Despite a detection of radio emission with ATCA, we find no evidence of a heavy jet in the X-ray spectrum, with tight upper limits on the relativistic emission lines seen by Díaz Trigo eight months later. Instead, we find deep absorption lines from a massive, highly ionized disk wind, whose properties can be probed with detailed photoionization models. We explore several scenarios to explain the two modes of massive outflow in this remarkable black hole system.

  11. Chandra Cluster Cosmology Project. II. Samples and X-Ray Data Reduction

    DEFF Research Database (Denmark)

    Vikhlinin, A.; Burenin, R. A.; Ebeling, H.

    2009-01-01

    We discuss the measurements of the galaxy cluster mass functions at z ≈ 0.05 and z ≈ 0.5 using high-quality Chandra observations of samples derived from the ROSAT PSPC All-Sky and 400 deg2 surveys. We provide a full reference for the data analysis procedures, present updated calibration of relati...... at a fixed mass threshold, e.g., by a factor of 5.0 ± 1.2 at M 500 = 2.5 × 1014 h –1 M sun between z = 0 and 0.5. This evolution reflects the growth of density perturbations, and can be used for the cosmological constraints complementing those from the distance-redshift relation....

  12. Pre-outburst Chandra observations of the recurrent nova T Pyxidis

    Science.gov (United States)

    Balman, Ş.

    2014-12-01

    Aims: I study the spectral, temporal, and spatial characteristics of the quiescent X-ray emission (not in outburst) of the recurrent nova T Pyx. Methods: I performed the spectral analysis of the X-ray data obtained using the Chandra Observatory, Advanced CCD Imaging Spectrometer (ACIS-S3) detector. I fit the spectra with several models that describe plasma emission characteristics. In addition, I calculated the light curve of the data and performed power spectral analysis using Fourier transform. Finally, I did high-resolution imaging analysis of the data at the subpixel level and produced radial surface brightness profiles. Results: I present a total of 98.8 ks (~ 3 × 30 ks) observation of T Pyx obtained with the ACIS-S3 detector onboard the Chandra Observatory obtained during the quiescent phase, about 2-3 months before its outburst in April 2011. The total Chandra spectrum of the source T Pyx gives a maximum temperature kTmax> 37.0 keV (2σ lower limit) with (0.9-1.5) × 10-13 erg s-1 cm-2 and (1.3-2.2) × 1032 erg s-1 (at 3.5 kpc) in the 0.1-50 keV range using a multitemperature plasma emission model with a power-law distribution of temperatures (i.e., CEVMKL in XSPEC). I find a ratio of (Lx/Ldisk) ≃ (2-7) × 10-4 and the ratio is smaller if Ldisk is higher than 3 × 1035 erg s-1 indicating considerable inefficiency of emission in the boundary layer. There is no soft X-ray blackbody emission from T Pyx with a 2σ upper limit on the blackbody temperature and the flux/luminosity as kTBB< 25 eV and Lsoft< 2.0 × 1033 erg s-1 in the 0.1-10.0 keV band. All fits yield only interstellar NH during quiescence. I suggest that T Pyx has an optically thin boundary layer merged with an advection-dominated accretion flow and/or X-ray corona in the inner disk indicating ongoing quasi-spherical accretion at (very) high rates during quiescent phases. Such a boundary layer structure may be excessively heating the white dwarf, influencing the thermonuclear runaway leading to

  13. Neutron Stars and Black Holes New clues from Chandra and XMM-Newton

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2002-01-01

    Neutron stars and black holes, the most compact astrophysical objects, have become observable in many different ways during the last few decades. We will first review the phenomenology and properties of neutron stars and black holes (stellar and supermassive) as derived from multiwavelength observatories. Recently much progress has been made by means of the new powerful X-ray observatories Chandra and XMM-Newton which provide a substantial increase in sensitivity as well as spectral and angular resolution compared with previous satellites like ROSAT and ASCA. We shall discuss in more detail two recent topics: (1) The attempts to use X-ray spectroscopy for measuring the radii of neutron stars which depend on the equation of state at supranuclear densities. Have quark stars been detected? (2) The diagnostics of the strong gravity regions around supermassive black holes using X-ray spectroscopy.

  14. Simultaneous FUSE, HST, and Chandra Observations or Intrinsic Absorbers in NGC 7469 and MRK 279

    Science.gov (United States)

    Sonneborn, George (Technical Monitor); Kriss, Gerard A.

    2004-01-01

    We obtained FUSE observations of NGC 7469 on 2002 Dec 13 & 14. The two exposures totaled only 7 ks. The observations only have good data in one channel, LiF1, due to channel alignment problems. These observations were obtained simultaneously with high-quality HST/STIS and Chandra HETG spectra. The previously known O VI absorption lines in the FUSE spectrum are detected at good signal to noise ratio, and a wide array of other intrinsic absorption lines are visible in the X-ray spectrum and in the STIS spectrum. Compared to prior FUSE observations, the continuum flux for this observation was 50% lower. We see the effects of this in the lowest-velocity O VI absorber, which we associate with the X-ray absorbing gas also detected in this object. This O VI absorber has only a 50% covering fraction, consistent with its covering only the continuum in this source, and its strength and inferred column density increased as the continuum flux of NGC 7469 decreased. This is consistent with the recombination expected from photoionization models of the highly ionized gas. We obtained FUSE observations of Mrk 279 on 2002 May 18. As for NGC 7469, channel alignment problems led to good data being present only in LiFl. While we obtained a much longer integration on the target than planned (47.4 ks vs. 31 ks requested), the UV flux was down a factor of 10 or more from previous HST and FUSE observations, and our wavelength coverage was restricted due to the channel alignment problems. These data still cover the important O VI emission line and absorption lines in Mrk 279. The FUSE flux also agrees well with the simultaneous HST STIS data, which have good signal to noise. We have also analyzed FUSE observations made at three earlier epochs. We detect the Fe K-alpha emission line in the Chandra spectrum, and its flux is consistent with the low X-ray continuum flux level of Mrk 279 at the time of the observation. Because of low signal-to-noise ratios (S/N) in the Chandra spectrum, no O

  15. Modeling Contamination Migration on the Chandra X-Ray Observatory - IV

    Science.gov (United States)

    O'Dell, Stephen L.; Swartz, Douglas A.; Tice, Neil William; Plucinsky, Paul P.; Marshall, Herman L.; Bogdan, Akos; Grant, Catherine E.; Tennant, Allyn F.; Dahmer, Matthew

    2017-01-01

    During its first 18 years of operation, the cold (about -60degC) optical blocking filters of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination, which attenuates low-energy x rays. Over the past several years, the accumulation rate, spatial distribution, and composition have changed. This evolution has motivated further analysis of contamination migration within and near the ACIS cavity, in part to evaluate potential bake-out scenarios intended to reduce the level of contamination. This paper, the fourth on this topic, reports the results of recent contamination-migration simulations and their relevance to a decision whether to bake-out the ACIS instrument.

  16. Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

    Science.gov (United States)

    Teng, Stacy H.; Schawinski, Kevin; Urry, C. Megan; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.; hide

    2012-01-01

    We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 1011 M that already have optical AGN signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (N(sub H) approx merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGN in these mergers are rare (0-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.

  17. PROBING WOLF–RAYET WINDS: CHANDRA/HETG X-RAY SPECTRA OF WR 6

    Energy Technology Data Exchange (ETDEWEB)

    Huenemoerder, David P.; Schulz, N. S. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States); Gayley, K. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Hamann, W.-R.; Oskinova, L.; Shenar, T. [Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam (Germany); Ignace, R. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37614 (United States); Nichols, J. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 34, Cambridge, MA 02138 (United States); Pollock, A. M. T., E-mail: dph@space.mit.edu, E-mail: ken.gayley@gmail.com, E-mail: wrh@astro.physik.uni-potsdam.de, E-mail: lida@astro.physik.uni-potsdam.de, E-mail: shtomer@astro.physik.uni-potsdam.de, E-mail: ignace@mail.etsu.edu, E-mail: jnichols@cfa.harvard.edu [European Space Agency, ESAC, Apartado 78, E-28691 Villanueva de la Cañada (Spain)

    2015-12-10

    With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like forbidden lines places the source of X-ray emission at tens to hundreds of stellar radii from the photosphere. Variability was present in X-rays and simultaneous optical photometry, but neither were correlated with the known period of the system or with each other. An enhanced abundance of sodium revealed nuclear-processed material, a quantity related to the evolutionary state of the star. The characterization of the extent and nature of the hot plasma in WR 6 will help to pave the way to a more fundamental theoretical understanding of the winds and evolution of massive stars.

  18. THE CHANDRA LOCAL VOLUME SURVEY: THE X-RAY POINT-SOURCE POPULATION OF NGC 404

    Energy Technology Data Exchange (ETDEWEB)

    Binder, B.; Williams, B. F.; Weisz, D. R. [University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195 (United States); Eracleous, M. [Department of Astronomy and Astrophysics and Center for Gravitational Wave Physics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Gaetz, T. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Cambridge, MA 02138 (United States); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Skillman, E. D. [University of Minnesota, Astronomy Department, 116 Church St. SE, Minneapolis, MN 55455 (United States)

    2013-02-15

    We present a comprehensive X-ray point-source catalog of NGC 404 obtained as part of the Chandra Local Volume Survey. A new 97 ks Chandra ACIS-S observation of NGC 404 was combined with archival observations for a total exposure of {approx}123 ks. Our survey yields 74 highly significant X-ray point sources and is sensitive to a limiting unabsorbed luminosity of {approx}6 Multiplication-Sign 10{sup 35} erg s{sup -1} in the 0.35-8 keV band. To constrain the nature of each X-ray source, cross-correlations with multi-wavelength data were generated. We searched overlapping Hubble Space Telescope observations for optical counterparts to our X-ray detections, but find only two X-ray sources with candidate optical counterparts. We find 21 likely low-mass X-ray binaries (LMXBs), although this number is a lower limit due to the difficulties in separating LMXBs from background active galactic nuclei. The X-ray luminosity functions (XLFs) in both the soft and hard energy bands are presented. The XLFs in the soft band (0.5-2 keV) and the hard band (2-8 keV) have a limiting luminosity at the 90% completeness limit of 10{sup 35} erg s{sup -1} and 10{sup 36} erg s{sup -1}, respectively, significantly lower than previous X-ray studies of NGC 404. We find the XLFs to be consistent with those of other X-ray populations dominated by LMXBs. However, the number of luminous (>10{sup 37} erg s{sup -1}) X-ray sources per unit stellar mass in NGC 404 is lower than is observed for other galaxies. The relative lack of luminous XRBs may be due to a population of LMXBs with main-sequence companions formed during an epoch of elevated star formation {approx}0.5 Gyr ago.

  19. Separating the BL Lac and cluster X-ray emissions in Abell 689 with Chandra

    Science.gov (United States)

    Giles, P. A.; Maughan, B. J.; Birkinshaw, M.; Worrall, D. M.; Lancaster, K.

    2012-01-01

    We present the results of a Chandra observation of the galaxy cluster Abell 689 (z = 0.279). Abell 689 is one of the most luminous clusters detected in the ROSAT All Sky Survey (RASS), but was flagged as possibly including significant point source contamination. The small point spread function of the Chandra telescope allows us to confirm this and separate the point source from the extended cluster X-ray emission. For the cluster, we determine a bolometric luminosity of Lbol= (3.3 ± 0.3) × 1044 erg s-1 and a temperature of kT = 5.1+2.2- 1.3 keV when including a physically motivated background model. We compare our measured luminosity for A689 to that quoted in the RASS, and find L0.1-2.4 keV= 2.8 × 1044 erg s-1, a value ˜10 times lower than the ROSAT measurement. Our analysis of the point source shows evidence for significant pile-up, with a pile-up fraction of ≃60 per cent. Sloan Digital Sky Survey spectra and Hubble Space Telescope (HST) images lead us to the conclusion that the point source within Abell 689 is a BL Lac object. Using radio and optical observations from the Very Large Array and HST archives, we determine αro= 0.50, αox= 0.77 and αrx= 0.58 for the BL Lac, which would classify it as being of 'high-energy peak BL Lac' type. Spectra extracted of A689 show a hard X-ray excess at energies above 6 keV that we interpret as inverse-Compton emission from aged electrons that may have been transported into the cluster from the BL Lac.

  20. Deep Chandra Observations of HCG 16. I. Active Nuclei, Star Formation, and Galactic Winds

    Science.gov (United States)

    O'Sullivan, E.; Zezas, A.; Vrtilek, J. M.; Giacintucci, S.; Trevisan, M.; David, L. P.; Ponman, T. J.; Mamon, G. A.; Raychaudhury, S.

    2014-10-01

    We present new, deep Chandra X-ray and Giant Metrewave Radio Telescope 610 MHz observations of the spiral-galaxy-rich compact group HCG 16, which we use to examine nuclear activity, star formation, and high-luminosity X-ray binary populations in the major galaxies. We confirm the presence of obscured active nuclei in NGC 833 and NGC 835, and identify a previously unrecognized nuclear source in NGC 838. All three nuclei are variable on timescales of months to years, and for NGC 833 and NGC 835 this is most likely caused by changes in accretion rate. The deep Chandra observations allow us to detect for the first time an Fe Kα emission line in the spectrum of the Seyfert 2 nucleus of NGC 835. We find that NGC 838 and NGC 839 are both starburst-dominated systems, with only weak nuclear activity, in agreement with previous optical studies. We estimate the star formation rates in the two galaxies from their X-ray and radio emission, and compare these results with estimates from the infrared and ultraviolet bands to confirm that star formation in both galaxies is probably declining after galaxy-wide starbursts were triggered ~400-500 Myr ago. We examine the physical properties of their galactic superwinds, and find that both have temperatures of ~0.8 keV. We also examine the X-ray and radio properties of NGC 848, the fifth largest galaxy in the group, and show that it is dominated by emission from its starburst.

  1. Deep Chandra observations of HCG 16. I. Active nuclei, star formation, and galactic winds

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, E.; Zezas, A.; Vrtilek, J. M.; David, L. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Giacintucci, S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Trevisan, M. [Instituto Nacional de Pesquisas Espaciais, Av. dos Astronautas 1758, 12227-010, São José dos Campos (Brazil); Ponman, T. J.; Raychaudhury, S. [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Mamon, G. A., E-mail: eosullivan@cfa.harvard.edu [Institut d' Astrophysique de Paris (UMR 7095 CNRS and UMPC), 98 bis Bd Arago, F-75014 Paris (France)

    2014-10-01

    We present new, deep Chandra X-ray and Giant Metrewave Radio Telescope 610 MHz observations of the spiral-galaxy-rich compact group HCG 16, which we use to examine nuclear activity, star formation, and high-luminosity X-ray binary populations in the major galaxies. We confirm the presence of obscured active nuclei in NGC 833 and NGC 835, and identify a previously unrecognized nuclear source in NGC 838. All three nuclei are variable on timescales of months to years, and for NGC 833 and NGC 835 this is most likely caused by changes in accretion rate. The deep Chandra observations allow us to detect for the first time an Fe Kα emission line in the spectrum of the Seyfert 2 nucleus of NGC 835. We find that NGC 838 and NGC 839 are both starburst-dominated systems, with only weak nuclear activity, in agreement with previous optical studies. We estimate the star formation rates in the two galaxies from their X-ray and radio emission, and compare these results with estimates from the infrared and ultraviolet bands to confirm that star formation in both galaxies is probably declining after galaxy-wide starbursts were triggered ∼400-500 Myr ago. We examine the physical properties of their galactic superwinds, and find that both have temperatures of ∼0.8 keV. We also examine the X-ray and radio properties of NGC 848, the fifth largest galaxy in the group, and show that it is dominated by emission from its starburst.

  2. VizieR Online Data Catalog: A catalog of nearby galaxies with Chandra obs. (She+, 2017)

    Science.gov (United States)

    She, R.; Ho, L. C.; Feng, H.

    2017-09-01

    We searched the public archive of the Chandra X-ray Observatory as of 2016 March and assembled a sample of 719 galaxies within 50Mpc with available Advanced CCD Imaging Spectrometer observations. By cross-correlation with the optical or near-infrared nuclei of these galaxies, 314 of them are identified to have an X-ray active galactic nucleus (AGN). The majority of them are low-luminosity AGNs and are unlikely X-ray binaries based upon their spatial distribution and luminosity functions. The AGN fraction is around 60% for elliptical galaxies and early-type spirals, but drops to roughly 20% for Sc and later types, consistent with previous findings in the optical. However, the X-ray survey is more powerful in finding weak AGNs, especially from regions with active star formation that may mask the optical AGN signature. For example, 31% of the H II nuclei are found to harbor an X-ray AGN. For most objects, a single power-law model subject to interstellar absorption is adequate to fit the spectrum, and the typical photon index is found to be around 1.8. For galaxies with a non-detection, their stacked Chandra image shows an X-ray excess with a luminosity of a few times 1037erg/s on average around the nuclear region, possibly composed of faint X-ray binaries. This paper reports on the technique and results of the survey; in-depth analysis and discussion of the results will be reported in forthcoming papers. (3 data files).

  3. Solar wind charge exchange emission in the Chandra deep field north

    Energy Technology Data Exchange (ETDEWEB)

    Slavin, Jonathan D.; Wargelin, Bradford J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Koutroumpa, Dimitra [LATMOS/IPSL, CNRS, Université Versailles Saint Quentin, 11 Boulevard d' Alembert, F-78280, Guyancourt (France)

    2013-12-10

    The diffuse soft X-ray background comes from distant galaxies, from hot Galactic gas, and from within the solar system. The latter emission arises from charge exchange between highly charged solar wind ions and neutral gas. This so-called solar wind charge exchange (SWCX) emission is spatially and temporally variable and interferes with our measurements of more distant cosmic emission while also providing important information on the nature of the solar wind-interstellar medium interaction. We present the results of our analysis of eight Chandra observations of the Chandra Deep Field North (CDFN) with the goal of measuring the cosmic and SWCX contributions to the X-ray background. Our modeling of both geocoronal and heliospheric SWCX emission is the most detailed for any observation to date. After allowing for ∼30% uncertainty in the SWCX emission and subtracting it from the observational data, we estimate that the flux of cosmic background for the CDFN in the O VII Kα, Kβ, and O VIII Lyα lines totals 5.8 ± 1.1 photons s{sup –1} cm{sup –2} sr{sup –1} (or LU). Heliospheric SWCX emission varied for each observation due to differences in solar wind conditions and the line of sight through the solar system, but was typically about half as strong as the cosmic background (i.e., one-third of the total) in those lines. The modeled geocoronal emission was 0.82 LU in one observation but averaged only 0.15 LU in the others. Our measurement of the cosmic background is lower than but marginally consistent with previous estimates based on XMM-Newton data.

  4. A Chandra-HETG view of MCG +8-11-11

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, K. D. [Department of Physics, Skidmore College, Saratoga Springs, NY 12866 (United States); Nowak, M. A., E-mail: kmurphy1@skidmore.edu [MIT Kavli Institute for Space Research, 77 Massachusetts Avenue, NE83-653, Cambridge, MA 02139 (United States)

    2014-12-10

    We present a spectral analysis of the 118 ks Chandra High Energy Transmission Gratings (HETG) observation of the X-ray bright Seyfert 1.5 galaxy MCG +8-11-11, in conjunction with 100 ks of archival Suzaku data, aimed at investigating the signatures of warm absorption and Compton reflection reported from previous Suzaku and XMM-Newton studies of the source. Contrary to previous results, we find that warm absorption is not required by the data. Instead, we report upper limits on absorption lines that are below previous (marginal) detections. Fe Kα line emission is clearly detected and is likely resolved with σ ∼ 0.02 keV with the HETG data. We applied self-consistent, broadband spectral-fitting models to the Chandra and Suzaku data to investigate this and other signatures of distant absorption and reflection. Utilizing in particular the MYTorus model, we find that the data are consistent with reprocessing by a distant, neutral torus that is marginally Compton-thick ( N {sub H} ∼10{sup 24}cm{sup –2}) and out of the line of sight. However, we do not find compelling evidence of a relativistically broadened Fe K emission line, which is often expected from type 1 active galactic nuclei. This is consistent with some, although not all, previous studies of MCG +8-11-11. A well-measured edge is identified by the HETG near 0.5 keV, indicating neutral absorption in the line of sight that is consistent with galactic absorption; however, the absorption may be partially intrinsic to the source. The HETG data are consistent with the presence of a soft excess, a feature that may be missed by considering the Suzaku data alone.

  5. Studies of Pulsar Wind Nebula in the Supernova Remnant IC443: Preliminary Observations from the Chandra Data

    Science.gov (United States)

    Ariyibi, E. A.

    2009-10-01

    Preliminary observations of the Chandra data were made in order to study the Pulsar Wind Nebula in the Supernova Remnant IC443. The Chandra X-ray observatory short observation on IC443 was centred on 13 chip ACIS. The CIAO analytical programme was used for the data analysis. The data were separated into point source, with an energy range of 2.1 to 10.0 keV, and diffuse source with energy less than 2.1 Kev. The resulting spectra were fitted to a power law. The observed density numbers and the normalised counts of both the point source and the diffuse source were used to describe the X-ray source. Afin d'étudier la "Pulsar wind Nebula" dans le reste de la Supernova IC 443, nous avons mené une exploitation préliminaire des observations provenant du satellite spatiale Chandra. L'observation brêve de IC 443, par Chandra fut centrée sur les composantes du spectromètre identifiées par la séquence 13. Le programme informatique CIAO fut utilisé pour l'analyse des données. Les données furent groupées en sources ponctuelles, chacune ayant des énergies allant de 2.1 a 10.0 kev ; et en sources diffuses chacune avec des énergies de moins de 2.1 kev. Les spectres obtenus furent interpolés à l'aide de fonction puissance. La densité de flux ainsi que le décompte des particules induites au détecteur par le rayonnement provenant des sources ponctuelles et diffuses furent utilisés pour décrire la source de rayon-X.

  6. A four-year XMM-Newton/Chandra monitoring campaign of the Galactic centre: analysing the X-ray transients

    NARCIS (Netherlands)

    Degenaar, N.; Wijnands, R.; Cackett, E.M.; Homan, J.; in 't Zand, J.J.M.; Kuulkers, E.; Maccarone, T.J.; van der Klis, M.

    2012-01-01

    We report on the results of a four-year long X-ray monitoring campaign of the central 1.2 square degrees of our Galaxy, performed with Chandra and XMM-Newton between 2005 and 2008. Our study focuses on the properties of transient X-ray sources that reach 2-10 keV luminosities of LX ≳ 1034 erg s-1

  7. Chandra Reveals Heavy Obscuration and Circumnuclear Star Formation in Seyfert 2 Galaxy NGC 4968

    Science.gov (United States)

    LaMassa, Stephanie M.; Yaqoob, Tahir; Levenson, N. A.; Boorman, Peter; Heckman, Timothy M.; Gandhi, Poshak; Rigby, Jane R.; Urry, C. Megan; Ptak, Andrew F.

    2017-01-01

    We present the Chandra imaging and spectral analysis of NGC 4968, a nearby (z = 0.00986) Seyfert 2 galaxy. We discover extended (approx. 1 kpc) X-ray emission in the soft band (0.5-2 keV) that is neither coincident with the narrow line region nor the extended radio emission. Based on spectral modeling, it is linked to on-going star formation [approx. 2.6-4 Mass compared to Earth yr(exp.- 1)]. The soft emission at circumnuclear scales (inner approx. 400 pc) originates from hot gas, with kT approx. 0.7 keV, while the most extended thermal emission is cooler (kT approx. 0.3 keV). We refine previous measurements of the extreme Fe K alpha equivalent width in this source (EW 2.5 + 2.6/-1.0 keV), which suggests the central engine is completely embedded within Compton-thick levels of obscuration. Using physically motivated models fit to the Chandra spectrum, we derive a Compton-thick column density [N(sub H) is greater than 1.25× 10(exp 24) cm(exp.- 2)] and an intrinsic hard (2-10 keV) X-ray luminosity of approx. 3-8× 10(exp. 42) erg s(exp. - 1) (depending on the presumed geometry of the obscurer), which is over two orders of magnitude larger than that observed. The large Fe K Alpha EW suggests a spherical covering geometry, which could be confirmed with X-ray measurements above 10 keV. NGC 4968 is similar to other active galaxies that exhibit extreme Fe K Alpha EWs (i.e., greater than 2 keV) in that they also contain on-going star formation. This work supports the idea that gas associated with nuclear star formation may increase the covering factor of the enshrouding gas and play a role in obscuring active galactic nuclei.

  8. Determination of Cluster Distances from Chandra Imaging Spectroscopy and Sunyaev-Zeldovich Effect Measurements. I; Analysis Methods and Initial Results

    Science.gov (United States)

    Bonamente, Massimiliano; Joy, Marshall K.; Carlstrom, John E.; LaRoque, Samuel J.

    2004-01-01

    X-ray and Sunyaev-Zeldovich Effect data ca,n be combined to determine the distance to galaxy clusters. High-resolution X-ray data are now available from the Chandra Observatory, which provides both spatial and spectral information, and interferometric radio measurements of the Sunyam-Zeldovich Effect are available from the BIMA and 0VR.O arrays. We introduce a Monte Carlo Markov chain procedure for the joint analysis of X-ray and Sunyaev-Zeldovich Effect data. The advantages of this method are the high computational efficiency and the ability to measure the full probability distribution of all parameters of interest, such as the spatial and spectral properties of the cluster gas and the cluster distance. We apply this technique to the Chandra X-ray data and the OVRO radio data for the galaxy cluster Abell 611. Comparisons with traditional likelihood-ratio methods reveal the robustness of the method. This method will be used in a follow-up paper to determine the distance of a large sample of galaxy clusters for which high-resolution Chandra X-ray and BIMA/OVRO radio data are available.

  9. Probing Large-scale Coherence between Spitzer IR and Chandra X-Ray Source-subtracted Cosmic Backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Cappelluti, N.; Urry, M. [Yale Center for Astronomy and Astrophysics, P.O. Box 208120, New Haven, CT 06520 (United States); Arendt, R. [University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Kashlinsky, A. [Observational Cosmology Laboratory, NASA Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Li, Y.; Hasinger, G. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Helgason, K. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States); Natarajan, P. [Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Finoguenov, A. [Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, D-85741, Garching bei München (Germany)

    2017-09-20

    We present new measurements of the large-scale clustering component of the cross-power spectra of the source-subtracted Spitzer -IRAC cosmic infrared background and Chandra -ACIS cosmic X-ray background surface brightness fluctuations Our investigation uses data from the Chandra Deep Field South, Hubble Deep Field North, Extended Groth Strip/AEGIS field, and UDS/SXDF surveys, comprising 1160 Spitzer hours and ∼12 Ms of Chandra data collected over a total area of 0.3 deg{sup 2}. We report the first (>5 σ ) detection of a cross-power signal on large angular scales >20″ between [0.5–2] keV and the 3.6 and 4.5 μ m bands, at ∼5 σ and 6.3 σ significance, respectively. The correlation with harder X-ray bands is marginally significant. Comparing the new observations with existing models for the contribution of the known unmasked source population at z < 7, we find an excess of about an order of magnitude at 5 σ confidence. We discuss possible interpretations for the origin of this excess in terms of the contribution from accreting early black holes (BHs), including both direct collapse BHs and primordial BHs, as well as from scattering in the interstellar medium and intra-halo light.

  10. Where Are the R-modes? Chandra Observations of Millisecond Pulsars

    Science.gov (United States)

    Mahmoodifar, Simin; Strohmayer, Tod E.

    2017-08-01

    We present the results of Chandra observations of two non-accreting millisecond pulsars PSRs J1640+2224 (J1640) and J1709+2313(J1709), with low inferred magnetic fields in order to constrain their surface temperatures, obtain limits on the amplitude of unstable r-modes in them and make comparisons with similar limits obtained for a sample of accreting LMXB neutron stars (NSs). We detect both pulsars in the X-ray band for the first time. We found upper limits on the global surface temperature of these pulsars that are ~ 3.3 - 4.7 × 105 K. These sources are several Gyr old. In all standard cooling models NSs cool to surface temperatures less than 104 K in less than 107 yr. While we derived upper limits on the surface temperatures of these sources, they appear to be consistent with the values measured for PSR J0437-4715 and J2124-3358. Taken together these results suggest that the surface temperatures of at least some MSPs are significantly higher, given their ages, than standard cooling models would suggest. For pulsars that are inside the r-mode instability window, r-mode dissipation can provide a potential source of reheating.

  11. Circumnuclear Star Formation and Heavy Obscuration Revealed by Chandra in NGC 4968

    Science.gov (United States)

    LaMassa, Stephanie M.; Yaqoob, Tahir; Levenson, Nancy; Boorman, Peter; Heckman, Timothy M.; Gandhi, Poshak; Rigby, Jane R.; Urry, C. Megan; Ptak, Andrew

    2017-08-01

    NGC 4968 is a nearby Seyfert 2 galaxy with evidence of extreme obscuration and circumnuclear star formation in its Chandra spectrum. Imaging analysis in the soft band (0.5 - 2 keV) reveals extended (~1 kpc) emission that is thermal in nature and ascribed to on-going star formation. We measure an Fe Kα equivalent width (EW) value of ~2.5 keV which is a clear indicator of Compton-thick levels of obscuration. Using physically motivated X-ray spectral models that self consistently treat the transmitted continuum, Compton scattered emission, and fluorescent line emission, we measure a column density above 1.25 x 1024 cm-2, though are unable to determine, with present data, whether the X-ray reprocessor takes the form of a toroidal or spherical geometry (in which case the column density may exceed 1025 cm-2). A spherical distribution of matter facilitiates the production of extreme Fe Kα EWs, suggesting that this geometry may be preferred. We speculate that on-going star formation increases the covering factor of the circumnuclear obscuration enshrouding the AGN. With upcoming NuSTAR observations, we will test whether the X-ray reprocessor geometry is indeed spherical and derive better constraints on the obscuring column density.

  12. Chandra and NuSTAR observations of supernova remnant RX J1713.7-3946

    Science.gov (United States)

    Tsuji, Naomi; Uchiyama, Yasunobu; Katsuda, Satoru; Berge, David; Aharonian, Felix

    2017-01-01

    Galactic cosmic rays are widely thought to be accelerated at supernova remnants (SNRs). SNR RX J1713.7-3946 is the strong sources of nonthermal radiation, making it one of the most well studied particle accelerators in our Galaxy. From the Chandra measurement of the proper motions in the northwest region of RX J1713.7-3946, the blast-wave shock speed is estimated as 3900 km/s. This relatively fast shock velocity, combined with the standard analytic solutions that describe the hydrodynamical properties of SNR evolution, supports the connection with SN393, and suggests that RX J1713.7-3946 would not have exited the ejecta-dominated phase, implying that the energy of accelerated particles has not reached the maximum yet. We have recently performed hard X-ray observations of RX J1713.7-3946 with NuSTAR (3-79 keV), providing fisrt imaging observations of RX J1713.7-3946 at the hard X-ray band above 10 keV. In preliminary fashion, we present spatially-resolved spectral analysis of the northwest part of this remnant and report the detection of an extremely hard X-ray component with NuSTAR.

  13. The Y SZ-YX Scaling Relation as Determined from Planck and Chandra

    Science.gov (United States)

    Rozo, Eduardo; Vikhlinin, Alexey; More, Surhud

    2012-11-01

    Sunyaev-Zeldovich (SZ) clusters surveys, such as Planck, the South Pole Telescope, and the Atacama Cosmology Telescope, will soon be publishing several hundred SZ-selected systems. The key ingredient required to transport the mass calibration from current X-ray-selected cluster samples to these SZ systems is the Y SZ-YX scaling relation. We constrain the amplitude, slope, and scatter of the Y SZ-YX scaling relation using SZ data from Planck and X-ray data from Chandra. We find a best-fit amplitude of ln (D 2 A Y SZ/CYX ) = -0.202 ± 0.024 at the pivot point CYX = 8 × 10-5 Mpc2. This corresponds to a Y SZ/YX ratio of 0.82 ± 0.024, in good agreement with X-ray expectations after including the effects of gas clumping. The slope of the relation is α = 0.916 ± 0.032, consistent with unity at ≈2.3σ. We are unable to detect intrinsic scatter, and find no evidence that the scaling relation depends on cluster dynamical state.

  14. CHANDRA OBSERVATION OF ABELL 1142: A COOL-CORE CLUSTER LACKING A CENTRAL BRIGHTEST CLUSTER GALAXY?

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yuanyuan; Weeren, Reinout van [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Buote, David A. [Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Gastaldello, Fabio, E-mail: yuanyuan.su@cfa.harvard.edu [INAF-IASF-Milano, Via E. Bassini 15, I-20133 Milano (Italy)

    2016-04-10

    Abell 1142 is a low-mass galaxy cluster at low redshift containing two comparable brightest cluster galaxies (BCGs) resembling a scaled-down version of the Coma Cluster. Our Chandra analysis reveals an X-ray emission peak, roughly 100 kpc away from either BCG, which we identify as the cluster center. The emission center manifests itself as a second beta-model surface brightness component distinct from that of the cluster on larger scales. The center is also substantially cooler and more metal-rich than the surrounding intracluster medium (ICM), which makes Abell 1142 appear to be a cool-core cluster. The redshift distribution of its member galaxies indicates that Abell 1142 may contain two subclusters, each of which contain one BCG. The BCGs are merging at a relative velocity of ≈1200 km s{sup −1}. This ongoing merger may have shock-heated the ICM from ≈2 keV to above 3 keV, which would explain the anomalous L{sub X}–T{sub X} scaling relation for this system. This merger may have displaced the metal-enriched “cool core” of either of the subclusters from the BCG. The southern BCG consists of three individual galaxies residing within a radius of 5 kpc in projection. These galaxies should rapidly sink into the subcluster center due to the dynamical friction of a cuspy cold dark matter halo.

  15. Where Are the R-modes? Chandra Observations of Millisecond Pulsars

    Science.gov (United States)

    Mahmoodifar, S.; Strohmayer, T.

    2017-10-01

    We present the results of Chandra observations of two non-accreting millisecond pulsars PSRs J1640+2224 (J1640) and J1709+2313(J1709), with low inferred magnetic fields in order to constrain their surface temperatures, obtain limits on the amplitude of unstable r-modes in them and make comparisons with similar limits obtained for a sample of accreting LMXB neutron stars (NSs). We detect both pulsars in the X-ray band for the first time. We found upper limits on the global surface temperature of these pulsars that are ˜ 3.3 × 10^5 - 4.7 × 10^5K. These sources are several Gyr old. In all standard cooling models NSs cool to surface temperatures less than 10^4K in less than 10^7 yr. While we derived upper limits on the surface temperatures of these sources, they appear to be consistent with the values measured for PSR J0437-4715 and J2124-3358. Taken together these results suggest that the surface temperatures of at least some MSPs are significantly higher, given their ages, than standard cooling models would suggest. For pulsars that are inside the r-mode instability window, r-mode dissipation can provide a potential source of reheating.

  16. Chandra X-Ray Observatory Image of a Massive Star Explosion

    Science.gov (United States)

    2000-01-01

    The Chandra X-Ray Observatory has captured this spectacular image of G292.0+1.8, a young, oxygen-rich supernova remnant with a pulsar at its center surrounded by outflowing material. This image shows a rapidly expanding shell of gas that is 36 light-years across and contains large amounts of elements such as oxygen, neon, magnesium, silicon and sulfur. Embedded in this cloud of multimillion-degree gas is a key piece of evidence linking neutron stars and supernovae produced by the collapse of massive stars. With an age estimated at 1,600 years, G292.0+1.8 is one of three known oxygen-rich supernovae in our galaxy. These supernovae are of great interest to astronomers because they are one of the primary sources of the heavy elements necessary to form planets and people. Scattered through the image are bluish knots of emissions containing material that is highly enriched in newly created oxygen, neon, and magnesium produced deep within the original star and ejected by the supernova explosion.

  17. A Chandra Archival Survey of the X-ray Source Populations of Nearby Galaxies

    Science.gov (United States)

    Kilgard, Roy; Wright, Simon; Fonseca, Gloria; Santini, Anthony; Fritze, Hannah

    2018-01-01

    We present results of a volume-limited Chandra archival survey of the X-ray point sources populations of nearby galaxies. We define our sample to include all observations of at least 5 ks of any galaxy within 15 Mpc. The complete sample is in excess of 15000 individual point sources, approximately half of which are contained with the D25 ellipses of galaxies. We present spectral and temporal analyses of this sample, from which we can cleanly define the parameter spaces in color, variability, and luminosity occupied by different classes of sources (e.g., LMXBs vs. HMXBs). For all sources, we perform detailed spatial modeling, spectral fitting, multiband X-ray photometry, and multimodal timing analyses. We further discuss source classes as a function of host galaxy morphology, star formation rate, stellar mass distribution, optical extent, interaction history, and metallicity. Finally, we discuss incompleteness in the sample, and what observations can be conducted in the following years to fill the gap.

  18. Chandra and NuSTAR Follow-up Observations of Swift-BAT-selected AGNs

    Science.gov (United States)

    Marchesi, S.; Tremblay, L.; Ajello, M.; Marcotulli, L.; Paggi, A.; Cusumano, G.; La Parola, V.; Segreto, A.

    2017-10-01

    Based on current models of the cosmic X-ray background (CXB), heavily obscured active galactic nuclei (AGNs) are expected to make up ˜10% of the peak emission of the CXB and ˜20% of the total population of AGNs, yet few of these sources have been recorded and characterized in current surveys. Here we present the Chandra follow-up observation of 14 AGNs detected by Swift-BAT. For five sources in the sample, NuSTAR observations in the 3-80 keV band are also available. The X-ray spectral fitting over the 0.3-150 keV energy range allows us to determine the main X-ray spectral parameters, such as the photon index and the intrinsic absorption, of these objects and to make hypotheses on the physical structures responsible for the observed spectra. We find that 13 of the 14 objects are absorbed AGNs, and one is a candidate Compton-thick AGN, having intrinsic absorption {N}{{H}}> {10}24 cm-2. Finally, we verified that the use of NuSTAR observations is strategic to strongly constrain the properties of obscured AGNs, since the best-fit values we obtained for parameters such as the power-law photon index Γ and the intrinsic absorption {N}{{H}} changed sometimes significantly fitting the spectra with and without the use of NuSTAR data.

  19. An Archival Chandra and XMM-Newton Survey of Type 2 Quasars

    Science.gov (United States)

    Jia, Jianjun; Ptak, Andrew Francis; Heckman, Timothy; Zakamska, Nadia L.

    2013-01-01

    In order to investigate obscuration in high-luminosity type 2 active galactic nuclei (AGNs), we analyzed Chandra and XMM-Newton archival observations for 71 type 2 quasars detected at 0.05 100 eV in the rest frame) and we detect this line in the other sources through a joint fit (spectral stacking). The correlation between the Fe K alpha and [O III] fluxes and the inverse correlation of the equivalent width of the Fe Ka line with the ratio of hard X-ray and [O III] fluxes is consistent with previous results for lower luminosity Seyfert 2 galaxies. We conclude that obscuration is the cause of the weak hard X-ray emission rather than intrinsically low X-ray luminosities. We find that about half of the population of optically selected type 2 quasars are likely to be Compton thick. We also find no evidence that the amount of X-ray obscuration depends on the AGN luminosity (over a range of more than three orders of magnitude in luminosity).

  20. A Chandra Archival Survey of the X-ray Source Populations of Nearby Galaxies

    Science.gov (United States)

    Kilgard, Roy E.; Wright, Simon; Fonseca, Gloria; Santini, Anthony; Fritze, Hannah

    2017-08-01

    We present results of a volume-limited Chandra archival survey of the X-ray point sources populations of nearby galaxies. We define our sample to include all observations of at least 5 ks of any galaxy within 15 Mpc. The complete sample is in excess of 15000 individual point sources, approximately half of which are contained with the D25 ellipses of galaxies. We present spectral and temporal analyses of this sample, from which we can cleanly define the parameter spaces in color, variability, and luminosity occupied by different classes of sources (e.g., LMXBs vs. HMXBs). For all sources, we perform detailed spatial modeling, spectral fitting, multiband X-ray photometry, and multimodal timing analyses. We further discuss source classes as a function of host galaxy morphology, star formation rate, stellar mass distribution, optical extent, interaction history, and metallicity. Finally, we discuss incompleteness in the sample, and what observations can be conducted in the following years to fill the gap.

  1. Study of X-ray point sources in NGC 5643 and NGC 7457 with Chandra

    Science.gov (United States)

    Singha, Akram Chandrajit; Devi, A. Senorita

    2017-12-01

    In the present study we have analysed Chandra Observational data of 2 galaxies: NGC 5643 and NGC 7457. Four point sources from NGC 5643 and two point sources from NGC 7457 with net counts ≥ 100 were considered for the present study. The spectra of these sources were fitted using two spectral models- an absorbed powerlaw and an absorbed disk blackbody. The spectrum of all the sources can be explained almost equally by both the models. We report here the discovery of 3 Ultraluminous X-ray sources (ULXs), X-1, X-2 and X-3 in the galaxy NGC 5643 and one ULX, X-5 in the galaxy NGC 7457. The spectral parameters suggest that all the above four ULX sources are in hard state (Γ ˜ 1.42-1.86), which may be due to thermal comptonization. If explained by absorbed diskblackbody model, the Black Hole (BH) mass of these sources are estimated to be stellar mass BHs with X-2, & X-5 accreting at super-Eddington rate while X-1 and X-3 at sub-Eddington rate. Another ULX, X-4 in NGC 5643 which is also accreting at super-Eddington rate is found to be a variable ULX with its luminosity reducing from 4.4 × 10^{40} ergs s^{-1} to 2.27 × 10^{40} ergs s^{-1} in the 0.3-10.0 keV energy range within a period of 11 years.

  2. Kepler's Supernova Remnant: A View from Chandra X-Ray Observatory

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1 Each top panel in the composite above shows the entire remnant. Each color in the composite represents a different region of the electromagnetic spectrum, from X-rays to infrared light. The X-ray and infrared data cannot be seen with the human eye. Astronomers have color-coded those data so they can be seen in these images. The bottom panels are close-up views of the remnant. In the bottom, center image, Hubble sees fine details in the brightest, densest areas of gas. The region seen in these images is outlined in the top, center panel. The images indicate that the bubble of gas that makes up the supernova remnant appears different in various types of light. Chandra reveals the hottest gas [colored blue and colored green], which radiates in X-rays. The blue color represents the higher-energy gas; the green, the lower-energy gas. Hubble shows the brightest, densest gas [colored yellow], which appears in visible light. Spitzer unveils heated dust [colored red], which radiates in infrared light.

  3. A VERY DEEP CHANDRA OBSERVATION OF A1795: THE COLD FRONT AND COOLING WAKE

    Energy Technology Data Exchange (ETDEWEB)

    Ehlert, Steven; McDonald, Michael; Miller, Eric D.; Bautz, Mark W. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); David, Laurence P., E-mail: sehlert@space.mit.edu [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-02-01

    We present a new analysis of very deep Chandra observations of the galaxy cluster A1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to resolve the thermodynamic structure of the intracluster medium (ICM) on length scales of ∼1 kpc near the cool core. We find several previously unresolved structures, including a high pressure feature to the north of the Brightest Cluster Galaxy (BCG) that appears to arise from the bulk motion of A1795's cool core. To the south of the cool core, we find low temperature (∼3 keV), diffuse ICM gas extending for distances of ∼50 kpc spatially coincident with previously identified filaments of Hα emission. Gas at similar temperatures is also detected in adjacent regions without any Hα emission. The X-ray gas coincident with the Hα filament has been measured to be cooling spectroscopically at a rate of ∼1 M{sub ⊙} yr{sup −1}, consistent with measurements of the star formation rate in this region as inferred from ultraviolet (UV) observations, suggesting that the star formation in this filament as inferred by its Hα and UV emission can trace its origin to the rapid cooling of dense, X-ray emitting gas. The Hα filament is not a unique site of cooler ICM, however, as ICM at similar temperatures and even higher metallicities not cospatial with Hα emission is observed just to the west of the Hα filament, suggesting that it may have been uplifted by A1795's central active galaxy. Further simulations of cool core sloshing and active galactic nucleus feedback operating in concert with one another will be necessary to understand how such a dynamic cool core region may have originated and why the Hα emission is so localized with respect to the cool X-ray gas.

  4. The Dark Matter Halos of Massive, Relaxed Galaxy Clusters Observed With Chandra

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Robert W.; /Heidelberg, Astron. Rechen Inst.; Allen, S.W.; /KIPAC, Menlo Park

    2006-10-11

    We use the Chandra X-ray Observatory to study the dark matter halos of 34 massive, dynamically relaxed galaxy clusters, spanning the redshift range 0.06 < z < 0.7. The observed dark matter and total mass (dark-plus-luminous matter) profiles can be approximated by the Navarro Frenk & White (hereafter NFW) model for cold dark matter (CDM) halos; for {approx} 80 percent of the clusters, the NFW model provides a statistically acceptable fit. In contrast, the singular isothermal sphere model can, in almost every case, be completely ruled out. We observe a well-defined mass-concentration relation for the clusters with a normalization and intrinsic scatter in good agreement with the predictions from simulations. The slope of the mass-concentration relation, c {infinity} M{sub vir}{sup a}/(1 + z){sup b} with a = -0.41 {+-} 0.11 at 95 percent confidence, is steeper than the value a {approx} -0.1 predicted by CDM simulations for lower mass halos. With the slope a included as a free fit parameter, the redshift evolution of the concentration parameter, b = 0.54 {+-} 0.47 at 95 percent confidence, is also slower than, but marginally consistent with, the same simulations (b {approx} 1). Fixing a {approx} -0.1 leads to an apparent evolution that is significantly slower, b = 0.20 {+-} 0.45, although the goodness of fit in this case is significantly worse. Using a generalized NFW model, we find the inner dark matter density slope, a, to be consistent with unity at 95 percent confidence for the majority of clusters. Combining the results for all clusters for which the generalized NFW model provides a good description of the data, we measure ? = 0.88 {+-} 0.29 at 95 percent confidence, in agreement with CDM model predictions.

  5. An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: Spectroscopic Redshifts

    Science.gov (United States)

    Danielson, A. L. R.; Swinbank, A. M.; Smail, Ian; Simpson, J. M.; Casey, C. M.; Chapman, S. C.; da Cunha, E.; Hodge, J. A.; Walter, F.; Wardlow, J. L.; Alexander, D. M.; Brandt, W. N.; de Breuck, C.; Coppin, K. E. K.; Dannerbauer, H.; Dickinson, M.; Edge, A. C.; Gawiser, E.; Ivison, R. J.; Karim, A.; Kovacs, A.; Lutz, D.; Menten, K.; Schinnerer, E.; Weiß, A.; van der Werf, P.

    2017-05-01

    We present spectroscopic redshifts of {\\text{}}{S}870μ {{m}} ≳ 2 mJy submillimeter galaxies (SMGs), which have been identified from the ALMA follow-up observations of 870 μm detected sources in the Extended Chandra Deep Field South (the ALMA-LESS survey). We derive spectroscopic redshifts for 52 SMGs, with a median of z = 2.4 ± 0.1. However, the distribution features a high-redshift tail, with ˜23% of the SMGs at z≥slant 3. Spectral diagnostics suggest that the SMGs are young starbursts, and the velocity offsets between the nebular emission and UV ISM absorption lines suggest that many are driving winds, with velocity offsets of up to 2000 km s-1. Using the spectroscopic redshifts and the extensive UV-to-radio photometry in this field, we produce optimized spectral energy distributions (SEDs) using Magphys, and use the SEDs to infer a median stellar mass of {M}\\star = (6 ± 1)× 1010 M {}⊙ for our SMGs with spectroscopic redshift. By combining these stellar masses with the star formation rates (measured from the far-infrared SEDs), we show that SMGs (on average) lie a factor of ˜5 above the so-called “main sequence” at z˜ 2. We provide this library of 52 template fits with robust and uniquely well-sampled SEDs as a resource for future studies of SMGs, and also release the spectroscopic catalog of ˜2000 (mostly infrared-selected) galaxies targeted as part of the spectroscopic campaign.

  6. Chandra Low Energy Transmission Grating Spectrum of SS Cygni in Outburst

    Energy Technology Data Exchange (ETDEWEB)

    Mauche, C W

    2004-02-20

    We have fitted the Chandra Low Energy Transmission Grating spectrum of SS Cygni in outburst with a single temperature blackbody suffering the photoelectric opacity of a neutral column density and the scattering opacity of an outflowing wind. We find that this simple model is capable of reproducing the essential features of the observed spectrum with the blackbody temperature T{sub bl} {approx} 250{+-}50 kK, hydrogen column density N{sub H} {approx} 5.0{sup +2.9}{sub -1.5}x10{sup 19} cm{sup -2}, fractional emitting area f {approx} 5.6{sup +60}{sub -4.5} x10{sup -3}, boundary layer luminosity Lbl {approx} 5{sup +18}{sub -3} x10{sup 33} erg s{sup -1}, wind velocity v {approx} 2500 km s{sup -1}, wind mass-loss rate w {approx} 1.1x10{sup 16} g s{sup -1}, and arbitrary values of the wind ionization fractions of 20 ions of O, Ne,Mg, Si, S, and Fe. Given that in outburst the accretion disk luminosity L{sub disk} {approx}1x10{sup 35} erg s{sup -1}, L{sub bl}/L{sub disk} {approx} 0.05{sup +0.18}{sub -0.03}, which can be explained if the white dwarf (or an equatorial belt thereon) is rotating with an angular velocity {Omega}{sub wd} {approx} 0.7{sup +0.1}{sub -0.2}Hz, hence V{sub rot}sini {approx} 2300 km s{sup -1}.

  7. A systematic Chandra study of Sgr A⋆: II. X-ray flare statistics

    Science.gov (United States)

    Yuan, Qiang; Wang, Q. Daniel; Liu, Siming; Wu, Kinwah

    2018-01-01

    The routinely flaring events from Sgr A⋆ trace dynamic, high-energy processes in the immediate vicinity of the supermassive black hole. We statistically study temporal and spectral properties, as well as fluence and duration distributions, of the flares detected by the Chandra X-ray Observatory from 1999 to 2012. The detection incompleteness and bias are carefully accounted for in determining these distributions. We find that the fluence distribution can be well characterized by a power law with a slope of 1.73^{+0.20}_{-0.19}, while the durations (τ in seconds) by a lognormal function with a mean log (τ)=3.39^{+0.27}_{-0.24} and an intrinsic dispersion σ =0.28^{+0.08}_{-0.06}. No significant correlation between the fluence and duration is detected. The apparent positive correlation, as reported previously, is mainly due to the detection bias (i.e. weak flares can be detected only when their durations are short). These results indicate that the simple self-organized criticality model has difficulties in explaining these flares. We further find that bright flares usually have asymmetric light curves with no statistically evident difference/preference between the rising and decaying phases in terms of their spectral/timing properties. Our spectral analysis shows that although a power-law model with a photon index of 2.0 ± 0.4 gives a satisfactory fit to the joint spectra of strong and weak flares, there is weak evidence for a softer spectrum of weaker flares. This work demonstrates the potential to use statistical properties of X-ray flares to probe their trigger and emission mechanisms, as well as the radiation propagation around the black hole.

  8. Chandra Observations of the Field Containing HESS J1616-508

    Science.gov (United States)

    Hare, Jeremy; Kargaltsev, Oleg; Pavlov, George G.; Rangelov, Blagoy; Volkov, Igor

    2017-06-01

    We report the results of three Chandra observations covering most of the extent of the TeV γ-ray source HESS J1616-508 and a search for a lower-energy counterpart to this source. We detect 56 X-ray sources, 37 of which have counterparts at lower frequencies, including a young massive star cluster, but none of them appear to be a particularly promising counterpart to the TeV source. The brightest X-ray source, CXOU J161423.4-505738, with a flux F 0.5-7 keV ≈ 5 × 10-13 erg cm-2 s-1, has a hard spectrum that is well fit by a power-law model with a photon index Γ = 0.2 ± 0.3 and is a likely intermediate polar CV candidate. No counterparts of this source were detected at other wavelengths. CVs are not known to produce extended TeV emission, and the source is also largely offset (19‧) from HESS J1616-508, making them unlikely to be associated. We have also set an upper limit on the X-ray flux of PSR J1614-5048 in the 0.5-8 keV band (F 0.5-8 keV association between the pulsar and the TeV source. We rule out a number of X-ray sources as possible counterparts to the TeV emission and do not find a plausible counterpart among the other sources. Lastly, we discuss the possible relation of PSR J1617-5055 to HESS J1616-508 in light of the new observations.

  9. Fifty M31 black hole candidates identified by Chandra and XMM-Newton

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, R.; Garcia, M. R.; Primini, F.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2014-08-10

    Over approximately the last five years, we have identified ∼35 black hole candidates (BHCs) in M31 from their X-ray spectra. Our BHCs exhibited 0.3-10 keV spectra consistent with the X-ray binary (XB) hard state at luminosities that are above the upper limit for neutron star (NS) XBs. When our BHC spectra were modeled with a disk blackbody + blackbody model for comparison with bright NS XBs, we found that the BHCs inhabited a different parameter space than the NS XBs. However, BH XBs may also exhibit a thermally dominated (TD) state that has never been seen in NS XBs; this TD state is most often observed in X-ray transients. We examined the ∼50 X-ray transients in our Chandra survey of M31 and found 13 with spectra suitable for analysis. We also examined two BHCs outside the field of view of our survey in the globular clusters B045 and B375. We have 42 strong BHCs and 8 plausible BHCs that may benefit from further observation. Of our 15 BHCs in globular clusters, 12 differ from NS spectra by >5σ. Due to improvements in our analysis, we have upgraded 10 previously identified plausible BHCs to strong BHCs. The mean maximum duty cycle of the 33 X-ray transients within 6' of M31* is 0.13; we estimate that >40% of the XBs in this region contain BH accretors. Remarkably, we estimate that BHCs contribute >90% of those XBs >10{sup 38} erg s{sup –1}.

  10. CHANDRA IDENTIFICATION OF 26 NEW BLACK HOLE CANDIDATES IN THE CENTRAL REGION OF M31

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, R.; Garcia, M. R.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics (CFA), Cambridge, MA 02138 (United States)

    2013-06-20

    We have previously identified 10 M31 black hole candidates (BHCs) in M31 from their X-ray properties alone. They exhibit ''hard state'' emission spectra that are seen at luminosities {approx}<10% Eddington in X-ray binaries (XBs) containing a neutron star (NS) or black hole, at luminosities that significantly exceed the NS threshold. Nine of these are associated with globular clusters (GCs); hence, these are most likely low mass X-ray binaries; eight are included in this survey. We have recently discovered that analysis of the long term 0.5-4.5 keV variability of XBs via structure functions allows us to separate XBs from active galactic nuclei, even though the emission spectra are often similar; this has enabled us to search for BHCs outside of GCs. We have identified 26 new BHCs (12 strong, 14 plausible) within 20' of the M31 nucleus (M31*), using 152 Chandra observations spaced over {approx}13 yr; some of our classifications were enhanced with XMM-Newton observations. Of these, seven appear within 100'' of M31*; this supports the theory suggesting that this region experiences enhanced XB production via dynamical processes similar to those seen in GCs. We have found a parameter space where our BHCs are separated from Galactic NS binaries: we show that modeling a simulated hard state spectrum with a disk blackbody + blackbody model yields parameters that lie outside the space occupied by NS binaries that are modeled this way. The probability that our BHCs all lie within the NS parameter space is {approx}3 Multiplication-Sign 10{sup -29}.

  11. Observations of the Jovian System with the Chandra X-Ray Observatory

    Science.gov (United States)

    Elsner, R. F.; Tennant, A. F.; Weisskopf, M. C.; Gladstone, G. R.; Waite, J. H.; Crary, F. J.; Grodent, D.; Howell, R. R.; Johnson, R. E.; Bhardwaj, A.; hide

    2002-01-01

    The {\\sl Chandra X-ray Observatory) observed the Jovian system on 25-26 Nov 1999 with the Advanced CCD Imaging Spectrometer (ACIS), in support of the Galileo flyby of Io, and on 18 Dec 2000 with the imaging array of the High Resolution Camera (HRC-I), in support of the Cassini flyby of Jupiter. These sensitive, very high spatial-resolution X-ray observations have revealed that Jupiter's northern x-ray aurora originates at a spot fixed in a coordinate system rotating with the planet at latitude (60--70 deg north) and longitude (160--180 deg System III). Contrary to previous expectations, this location is poleward of the main FUV auroral oval and the foot of the Io Flux Tube, and is apparently connected magnetically to a region of the outer magnetosphere beyond $\\sim$30 Jupiter radii. The northern auroral x-ray emission varies with a period $\\sim$45 minute and has a an average power of $\\sim$1 GW. The earlier view that Jupiter's x-ray aurora resulted from the precipitation of heavy ions from the outer edge of the lo Plasma Torus is now in doubt. Jupiter's disk also emits x-rays with a power of $\\sim$2 GW, perhaps resulting from reprocessing of solar x-rays in its atmosphere. These observations reveal for the first time x-ray emission from the Io Plasma Torus, with a power of $\\sim$0.1 Gw. The origin of this emission is not currently understood, although bremmstrahlung from non-thermal electrons may play a significant role. Finally, we report the discovery of very faint ($\\sim$1--2 MW) soft x-ray emission from the Galilean satellites Io, Europa, and probably Ganymede, most likely as a result of bombardment of their surfaces by energetic ($ greater than $10 keV) H, O, and S ions from the region of the Io Plasma Torus.

  12. Deep Chandra Observation and Numerical Studies of the Nearest Cluster Cold Front in the Sky

    Science.gov (United States)

    Werner, N.; ZuHone, J. A.; Zhuravleva, I.; Ichinohe, Y.; Simionescu, A.; Allen, S. W.; Markevitch, M.; Fabian, A. C.; Keshet, U.; Roediger, E.; hide

    2015-01-01

    We present the results of a very deep (500 ks) Chandra observation, along with tailored numerical simulations, of the nearest, best resolved cluster cold front in the sky, which lies 90 kpc (19 arcmin) to the north-west of M87. The northern part of the front appears the sharpest, with a width smaller than 2.5 kpc (1.5 Coulomb mean free paths; at 99 per cent confidence). Everywhere along the front, the temperature discontinuity is narrower than 4-8 kpc and the metallicity gradient is narrower than 6 kpc, indicating that diffusion, conduction and mixing are suppressed across the interface. Such transport processes can be naturally suppressed by magnetic fields aligned with the cold front. Interestingly, comparison to magnetohydrodynamic simulations indicates that in order to maintain the observed sharp density and temperature discontinuities, conduction must also be suppressed along the magnetic field lines. However, the northwestern part of the cold front is observed to have a non-zero width. While other explanations are possible, the broadening is consistent with the presence of Kelvin-Helmholtz instabilities (KHI) on length-scales of a few kpc. Based on comparison with simulations, the presence of KHI would imply that the effective viscosity of the intracluster medium is suppressed by more than an order of magnitude with respect to the isotropic Spitzer-like temperature dependent viscosity. Underneath the cold front, we observe quasi-linear features that are approximately 10 per cent brighter than the surrounding gas and are separated by approximately 15 kpc from each other in projection. Comparison to tailored numerical simulations suggests that the observed phenomena may be due to the amplification of magnetic fields by gas sloshing in wide layers below the cold front, where the magnetic pressure reaches approximately 5-10 per cent of the thermal pressure, reducing the gas density between the bright features.

  13. CHANDRA OBSERVATIONS OF 3C RADIO SOURCES WITH z < 0.3. II. COMPLETING THE SNAPSHOT SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Tremblay, G. R. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Muenchen (Germany); Harris, D. E.; O' Dea, C. P. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Kharb, P.; Axon, D. [Department of Physics, Rochester Institute of Technology, Carlson Center for Imaging Science 76-3144, 84 Lomb Memorial Dr., Rochester, NY 14623 (United States); Balmaverde, B.; Capetti, A. [INAF-Osservatorio Astrofisico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese (Italy); Baum, S. A. [Carlson Center for Imaging Science 76-3144, 84 Lomb Memorial Dr., Rochester, NY 14623 (United States); Chiaberge, M.; Macchetto, F. D.; Sparks, W. [Space Telescope Science Institute, 3700 San Martine Drive, Baltimore, MD 21218 (United States); Gilli, R. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Giovannini, G. [INAF-Istituto di Radioastronomia di Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Grandi, P.; Torresi, E. [INAF-IASF-Istituto di Astrofisica Spaziale e fisica Cosmica di Bologna, Via P. Gobetti 101, I-40129 Bologna (Italy); Risaliti, G. [INAF-Osservatorio Astronomico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

    2012-12-15

    We report on the second round of Chandra observations of the 3C snapshot survey developed to observe the complete sample of 3C radio sources with z < 0.3 for 8 ks each. In the first paper, we illustrated the basic data reduction and analysis procedures performed for the 30 sources of the 3C sample observed during Chandra Cycle 9, while here we present the data for the remaining 27 sources observed during Cycle 12. We measured the X-ray intensity of the nuclei and of any radio hot spots and jet features with associated X-ray emission. X-ray fluxes in three energy bands, i.e., soft, medium, and hard, for all the sources analyzed are also reported. For the stronger nuclei, we also applied the standard spectral analysis, which provides the best-fit values of the X-ray spectral index and absorbing column density. In addition, a detailed analysis of bright X-ray nuclei that could be affected by pile-up has been performed. X-ray emission was detected for all the nuclei of the radio sources in our sample except for 3C 319. Among the current sample, there are two compact steep spectrum radio sources, two broad-line radio galaxies, and one wide angle tail radio galaxy, 3C 89, hosted in a cluster of galaxies clearly visible in our Chandra snapshot observation. In addition, we also detected soft X-ray emission arising from the galaxy cluster surrounding 3C 196.1. Finally, X-ray emission from hot spots has been found in three FR II radio sources and, in the case of 3C 459, we also report the detection of X-ray emission associated with the eastern radio lobe as well as X-ray emission cospatial with radio jets in 3C 29 and 3C 402.

  14. Simultaneous NuSTAR/Chandra Observations of the Bursting Pulsar GRO J1744-28 During its Third Reactivation

    Science.gov (United States)

    Younes, G.; Kouveliotou, C.; Grefenstette, B. W.; Tomsick, J. A.; Tennant, A.; Finger, M. H.; Furst, F.; Pottschmidt, K.; Bhalerao, V.; Boggs, S. E.; hide

    2015-01-01

    We report on a 10 ks simultaneous Chandra/High Energy Transmission Grating (HETG)-Nuclear Spectroscopic Telescope Array (NuSTAR) observation of the Bursting Pulsar, GRO J1744-28, during its third detected outburst since discovery and after nearly 18 yr of quiescence. The source is detected up to 60 keV with an Eddington persistent flux level. Seven bursts, followed by dips, are seen with Chandra, three of which are also detected with NuSTAR. Timing analysis reveals a slight increase in the persistent emission pulsed fraction with energy (from 10% to 15%) up to 10 keV, above which it remains constant. The 0.5-70 keV spectra of the persistent and dip emission are the same within errors and well described by a blackbody (BB), a power-law (PL) with an exponential rolloff, a 10 keV feature, and a 6.7 keV emission feature, all modified by neutral absorption. Assuming that the BB emission originates in an accretion disk, we estimate its inner (magnetospheric) radius to be about 4 x 10(exp 7) cm, which translates to a surface dipole field B approximately 9 x 10(exp 10) G. The Chandra/HETG spectrum resolves the 6.7 keV feature into (quasi-)neutral and highly ionized Fe XXV and Fe XXVI emission lines. XSTAR modeling shows these lines to also emanate from a truncated accretion disk. The burst spectra, with a peak flux more than an order of magnitude higher than Eddington, are well fit with a PL with an exponential rolloff and a 10 keV feature, with similar fit values compared to the persistent and dip spectra. The burst spectra lack a thermal component and any Fe features. Anisotropic (beamed) burst emission would explain both the lack of the BB and any Fe components.

  15. Constraints on axino warm dark matter from X-ray observation at the Chandra telescope and SPI

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Paramita [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen, D-52056 Aachen (Germany); Mukhopadhyaya, Biswarup [Regional Centre for Accelerator-based Particle Physics, Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad 211019 (India); Roy, Sourov [Department of Theoretical Physics, Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Kolkata 700032 (India); Vempati, Sudhir K., E-mail: paramita@physik.rwth-aachen.de, E-mail: biswarup@hri.res.in, E-mail: tpsr@iacs.res.in, E-mail: vempati@cts.iisc.ernet.in [Centre for High Energy Physics, Indian Institute of Science, Bangalore 560012 (India)

    2012-05-01

    A sufficiently long lived warm dark matter could be a source of X-rays observed by satellite based X-ray telescopes. We consider axinos and gravitinos with masses between 1 keV and 100 keV in supersymmetric models with small R-parity violation. We show that axino dark matter receives significant constraints from X-ray observations of Chandra and SPI, especially for the lower end of the allowed range of the axino decay constant f{sub a}, while the gravitino dark matter remains unconstrained.

  16. THE CHANDRA X-RAY SURVEY OF PLANETARY NEBULAE (CHANPLANS): PROBING BINARITY, MAGNETIC FIELDS, AND WIND COLLISIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kastner, J. H.; Montez, R. Jr.; Rapson, V. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Balick, B. [Department of Astronomy, University of Washington, Seattle, WA (United States); Frew, D. J.; De Marco, O.; Parker, Q. A. [Department of Physics and Astronomy and Macquarie Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109 (Australia); Miszalski, B. [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Sahai, R. [Jet Propulsion Laboratory, California Institute of Technology, MS 183-900, Pasadena, CA 91109 (United States); Blackman, E.; Frank, A. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Chu, Y.-H. [Department of Astronomy, University of Illinois, Champagne-Urbana, IL (United States); Guerrero, M. A. [Instituto de Astrofisica de Astronomia, Glorieta de la Astronomia s/n, Granada 18008 (Spain); Lopez, J. A. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Campus Ensenada, Apdo. Postal 22860, Ensenada, B. C. (Mexico); Zijlstra, A. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Behar, E. [Department of Physics, Technion (Israel); Bujarrabal, V. [Observatorio Astronomico Nacional, Apartado 112, E-28803, Alcala de Henares (Spain); Corradi, R. L. M. [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Nordhaus, J. [Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States); Sandin, C., E-mail: jhk@cis.rit.edu, E-mail: soker@physics.technion.ac.il, E-mail: eva.villaver@uam.es [Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); and others

    2012-08-15

    We present an overview of the initial results from the Chandra Planetary Nebula Survey (CHANPLANS), the first systematic (volume-limited) Chandra X-Ray Observatory survey of planetary nebulae (PNe) in the solar neighborhood. The first phase of CHANPLANS targeted 21 mostly high-excitation PNe within {approx}1.5 kpc of Earth, yielding four detections of diffuse X-ray emission and nine detections of X-ray-luminous point sources at the central stars (CSPNe) of these objects. Combining these results with those obtained from Chandra archival data for all (14) other PNe within {approx}1.5 kpc that have been observed to date, we find an overall X-ray detection rate of {approx}70% for the 35 sample objects. Roughly 50% of the PNe observed by Chandra harbor X-ray-luminous CSPNe, while soft, diffuse X-ray emission tracing shocks-in most cases, 'hot bubbles'-formed by energetic wind collisions is detected in {approx}30%; five objects display both diffuse and point-like emission components. The presence (or absence) of X-ray sources appears correlated with PN density structure, in that molecule-poor, elliptical nebulae are more likely to display X-ray emission (either point-like or diffuse) than molecule-rich, bipolar, or Ring-like nebulae. All but one of the point-like CSPNe X-ray sources display X-ray spectra that are harder than expected from hot ({approx}100 kK) central stars emitting as simple blackbodies; the lone apparent exception is the central star of the Dumbbell nebula, NGC 6853. These hard X-ray excesses may suggest a high frequency of binary companions to CSPNe. Other potential explanations include self-shocking winds or PN mass fallback. Most PNe detected as diffuse X-ray sources are elliptical nebulae that display a nested shell/halo structure and bright ansae; the diffuse X-ray emission regions are confined within inner, sharp-rimmed shells. All sample PNe that display diffuse X-ray emission have inner shell dynamical ages {approx}< 5 Multiplication

  17. VizieR Online Data Catalog: 6Ms Chandra long-term analyses of AGNs (Yang+, 2016)

    Science.gov (United States)

    Yang, G.; Brandt, W. N.; Luo, B.; Xue, Y. Q.; Bauer, F. E.; Sun, M. Y.; Kim, S.; Schulze, S.; Zheng, X. C.; Paolillo, M.; Shemmer, O.; Liu, T.; Schneider, D. P.; Vignali, C.; Vito, F.; Wang, J.-X.

    2017-02-01

    This work is based on the Chandra CDF-S data. The observations were taken from 1999 October to 2015 January with a total observation time of 5.7Ms. In total, there are 84 observations utilized with median exposure time ~60ks. All of the 84 observations were performed using the Advanced CCD Imaging Spectrometer imaging array (ACIS-I). See B. Luo et al. 2016, in prep (L16) for more observation details. Sixty-eight sources are selected with 649-11283 counts; the median number of counts is 1399. (1 data file).

  18. An x-ray study of massive star forming regions with CHANDRA

    Science.gov (United States)

    Wang, Junfeng

    2007-08-01

    Massive stars are characterized by powerful stellar winds, strong ultraviolet (UV) radiation, and consequently devastating supernovae explosions, which have a profound influence on their natal clouds and galaxy evolution. However, the formation and evolution of massive stars themselves and how their low-mass siblings are affected in the wind-swept and UV-radiation-dominated environment are not well understood. Much of the stellar populations inside of the massive star forming regions (MSFRs) are poorly studied in the optical and IR wavelengths because of observational challenges caused by large distance, high extinction, and heavy contamination from unrelated sources. Although it has long been recognized that X-rays open a new window to sample the young stellar populations residing in the MSFRs, the low angular resolution of previous generation X-ray telescopes has limited the outcome from such studies. The sensitive high spatial resolution X-ray observations enabled by the Chandra X- ray Observatory and the Advanced CCD Imaging Spectrometer (ACIS) have significantly improved our ability to study the X-ray-emitting populations in the MSFRs in the last few years. In this thesis, I analyzed seven high spatial resolution Chandra /ACIS images of two massive star forming complexes, namely the NGC 6357 region hosting the 1 Myr old Pismis 24 cluster (Chapter 3) and the Rosette Complex including the 2 Myr old NGC 2244 cluster immersed in the Rosette Nebula (Chapter 4), embedded clusters in the Rosette Molecular Cloud (RMC; Chapter 5), and a triggered cluster NGC 2237 (Chapter 6). The X-ray sampled stars were studied in great details. The unique power of X-ray selection of young stellar cluster members yielded new knowledge in the stellar populations, the cluster structures, and the star formation histories. The census of cluster members is greatly improved in each region. A large fraction of the X-ray detections have optical or near-infrared (NIR) stellar counterparts

  19. Clusters, groups, and filaments in the Chandra deep field-south up to redshift 1

    Energy Technology Data Exchange (ETDEWEB)

    Dehghan, S.; Johnston-Hollitt, M., E-mail: siamak.dehghan@vuw.ac.nz [School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140 (New Zealand)

    2014-03-01

    We present a comprehensive structure detection analysis of the 0.3 deg{sup 2} area of the MUSYC-ACES field, which covers the Chandra Deep Field-South (CDFS). Using a density-based clustering algorithm on the MUSYC and ACES photometric and spectroscopic catalogs, we find 62 overdense regions up to redshifts of 1, including clusters, groups, and filaments. We also present the detection of a relatively small void of ∼10 Mpc{sup 2} at z ∼ 0.53. All structures are confirmed using the DBSCAN method, including the detection of nine structures previously reported in the literature. We present a catalog of all structures present, including their central position, mean redshift, velocity dispersions, and classification based on their morphological and spectroscopic distributions. In particular, we find 13 galaxy clusters and 6 large groups/small clusters. Comparison of these massive structures with published XMM-Newton imaging (where available) shows that 80% of these structures are associated with diffuse, soft-band (0.4-1 keV) X-ray emission, including 90% of all objects classified as clusters. The presence of soft-band X-ray emission in these massive structures (M {sub 200} ≥ 4.9 × 10{sup 13} M {sub ☉}) provides a strong independent confirmation of our methodology and classification scheme. In the closest two clusters identified (z < 0.13) high-quality optical imaging from the Deep2c field of the Garching-Bonn Deep Survey reveals the cD galaxies and demonstrates that they sit at the center of the detected X-ray emission. Nearly 60% of the clusters, groups, and filaments are detected in the known enhanced density regions of the CDFS at z ≅ 0.13, 0.52, 0.68, and 0.73. Additionally, all of the clusters, bar the most distant, are found in these overdense redshift regions. Many of the clusters and groups exhibit signs of ongoing formation seen in their velocity distributions, position within the detected cosmic web, and in one case through the presence of tidally

  20. Where Are the r-modes? Chandra Observations of Millisecond Pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoodifar, Simin; Strohmayer, Tod [Astrophysics Science Division and Joint Space-Science Institute, NASA' s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2017-05-10

    We present the results of Chandra observations of two non-accreting millisecond pulsars, PSRs J1640+2224 (J1640) and J1709+2313 (J1709), with low inferred magnetic fields and spin-down rates in order to constrain their surface temperatures, obtain limits on the amplitude of unstable r -modes in them, and make comparisons with similar limits obtained for a sample of accreting low-mass X-ray binary (LMXB) neutron stars. We detect both pulsars in the X-ray band for the first time. They are faint, with inferred soft X-ray fluxes (0.3–3 keV) of ≈6 × 10{sup −15} and 3 × 10{sup −15} erg cm{sup −2} s{sup −1} for J1640 and J1709, respectively. Spectral analysis assuming hydrogen atmosphere emission gives global effective temperature upper limits (90% confidence) of 3.3–4.3 × 10{sup 5} K for J1640 and 3.6–4.7 × 10{sup 5} K for J1709, where the low end of the range corresponds to canonical neutron stars ( M = 1.4 M {sub ⊙}), and the upper end corresponds to higher-mass stars ( M = 2.21 M {sub ⊙}). Under the assumption that r -mode heating provides the thermal support, we obtain dimensionless r -mode amplitude upper limits of 3.2–4.8 × 10{sup −8} and 1.8–2.8 × 10{sup −7} for J1640 and J1709, respectively, where again the low end of the range corresponds to lower-mass, canonical neutron stars ( M = 1.4 M {sub ⊙}). These limits are about an order of magnitude lower than those we derived previously for a sample of LMXBs, except for the accreting millisecond X-ray pulsar SAX J1808.4–3658, which has a comparable amplitude limit to J1640 and J1709.

  1. X-ray properties of the z ~ 4.5 Lyman-alpha Emitters in the Chandra Deep Field South Region

    OpenAIRE

    Zheng, Z. Y.; Wang, J. X.; Finkelstein, S. L.; Malhotra, S.; Rhoads, J. E.; Finkelstein, K. D.

    2010-01-01

    We report the first X-ray detection of 113 Lyman-alpha emitters at redshift z ~ 4.5. Only one source (J033127.2-274247) is detected in the Extended Chandra Deep Field South (ECDF-S) X-ray data, and has been spectroscopically confirmed as a z = 4.48 quasar with $L_X = 4.2\\times 10^{44}$ erg/s. The single detection gives a Lyman-alpha quasar density consistent with the X-ray luminosity function of quasars. The coadded counts of 22 Lyman-alpha emitters (LAEs) in the central Chandra Deep Field So...

  2. VizieR Online Data Catalog: XMM-Newton and Chandra monitoring of Sgr A* (Ponti+, 2015)

    Science.gov (United States)

    Ponti, G.; de, Marco B.; Morris, M. R.; Merloni, A.; Munoz-Darias, T.; Clavel, M.; Haggard, D.; Zhang, S.; Nandra, K.; Gillessen, S.; Mori, K.; Neilsen, J.; Rea, N.; Degenaar, N.; Terrier, R.; Goldwurm, A.

    2018-01-01

    As of 2014 November 11 the XMM-Newton archive contains 37 public observations that can be used for our analysis of Sgr A*. In addition, we consider four new observations aimed at monitoring the interaction between the G2 object and Sgr A*, performed in fall 2014 (see Table A4). A total of 41 XMM-Newton data sets are considered in this work. All the 46 Chandra observations accumulated between 1999 and 2011 and analysed here are obtained with the ACIS-I camera without any gratings on (see Table A1). From 2012 onwards, data from the ACIS-S camera were also employed. The 2012 Chandra "X-ray Visionary Project" (XVP) is composed of 38 High-Energy Transmission Grating (HETG) observations with the ACIS-S camera at the focus (Nowak et al. 2012ApJ...759...95N; Neilsen et al. 2013ApJ...774...42N; 2015ApJ...799..199N; Wang et al. 2013Sci...341..981W; see Table A2). The first two observations of the 2013 monitoring campaign were performed with the ACIS-I instrument, while the ACIS-S camera was employed in all the remaining observations, after the outburst of SGR J1745-2900 on 2013 April 25. Three observations between 2013 May and July were performed with the HETG on, while all the remaining ones do not employ any gratings (see Table A2). (4 data files).

  3. The Observed On-Orbit Background of the ACIS Instrument of the Chandra X-Ray Observatory

    Science.gov (United States)

    Plucinsky, Paul P.; Lavoie, Anthony R. (Technical Monitor)

    2000-01-01

    We have analyzed calibration data acquired during the Orbital Activation and Checkout (OAC) phase of the Chandra X-ray Observatory (CXO) mission in order to characterize the background of the Advanced CCD Imaging Spectrometer (ACIS) produced by charged particles and non-cosmic x-rays. The ACIS instrument contains eight Front-Illuminated (FI) CCDs and two Back-Illuminated (BI) CCDs. The FI and BI CCDs exhibit dramatically different responses to enhancements in the particle flux. The FI CCDs show relatively little increase in the overall count rate, typical increases are 1-3 counts/s; the BI CCDs show large excursions to as high as 100 counts/s. The directions of these intervals of enhanced background are highly variable ranging from 100 s to 5000 s. The spatial distribution of these background events is relatively flat across the detectors. The spectral distribution can be characterized by a simple power law. The events produce morphologies which are similar to cosmic x-ray events, so that morphology alone cannot be used as a rejection criterion. We explore the correlation of these times of high background with the data from Chandra's on-board radiation monitor, the EPHIN (Electron, Proton, Helium Instrument particle detector) instrument and archival data from the Advanced Composition Explorer (ACE) satellite. We discuss strategies for observers to identify and exclude times of high background and to model and subtract the background events from their data.

  4. Buried Black Hole Growth in Advanced Mergers: The Discovery of a Large Population of Dual AGN Candidates by Chandra

    Science.gov (United States)

    Satyapal, Shobita; Secrest, Nathan; Ellison, Sara L.; Ricci, Claudio; Pfeifle, Ryan William; Blecha, Laura; Rothberg, Barry; Gliozzi, Mario; Constantin, Anca; Ferguson, Jason

    2018-01-01

    Interactions between galaxies are predicted to cause gas inflows that can potentially trigger nuclear activity. Since the inflowing material can obscure the central regions of interacting galaxies, a potential limitation of previous optical studies is that obscured active galactic nuclei (AGNs) can be missed at various stages along the merger sequence. In a recent large mid-infrared study of AGNs in mergers, we demonstrated that the fraction of obscured AGNs increases with merger stage, with the most energetically dominant optically obscured AGNs becoming more prevalent in the most advanced mergers, consistent with theoretical predictions. In a recent Chandra program, we discovered 8 out of 15 infrared-selected advanced mergers that display two nuclear X-ray sources with separations of a few kiloparsecs consistent with highly absorbed dual AGNs, demonstrating that WISE pre-selection may be effective in identifying a new population of optically invisible dual AGNs. These observations reveal that infrared and X-ray observations are critical in uncovering the most efficient environments for supermassive black hole accretion and a key stage in galaxy evolution. In this talk, I will discuss Chandra, NuSTAR, and near-infrared spectroscopic observations of these dual AGN candidates and recent hydrodynamic simulations that predict that this key stage in galaxy evolution is expected to be highly obscured.

  5. Comparative Analysis and Variability of the Jovian X-Ray Spectra Detected by the Chandra and XMM-Newton Observatories

    Energy Technology Data Exchange (ETDEWEB)

    Hui, Yawei [ORNL; Schultz, David Robert [ORNL; Kharchenko, Vasili A [ORNL; Bhardwaj, Anil [Vikram Sarabhai Space Center, Trivandrum, India; Branduardi-Raymont, Graziella [University College, London; Stancil, Phillip C. [University of Georgia, Athens, GA; Cravens, Thomas E. E. [University of Kansas; Lisse, Carey M. [Johns Hopkins University; Dalgarno, A. [Harvard-Smithsonian Center for Astrophysics

    2010-01-01

    Expanding upon recent work, a more comprehensive spectral model based on charge exchange induced X-ray emission by ions precipitating into the Jovian atmosphere is used to provide new understanding of the polar auroras. In conjunction with the Xspec spectral fitting software, the model is applied to analyze observations from both Chandra and XMM-Newton by systematically varying the initial precipitating ion parameters to obtain the best fit model for the observed spectra. In addition to the oxygen and sulfur ions considered previously, carbon is included to discriminate between solar wind and Jovian magnetospheric ion origins, enabled by the use of extensive databases of both atomic collision cross sections and radiative transitions. On the basis of fits to all the Chandra observations, we find that carbon contributes negligibly to the observed polar X-ray emission suggesting that the highly accelerated precipitating ions are of magnetospheric origin. Most of the XMM-Newton fits also favor this conclusion with one exception that implies a possible carbon contribution. Comparison among all the spectra from these two observatories in light of the inferred initial energies and relative abundances of precipitating ions from the modeling show that they are significantly variable in time (observation date) and space (north and south polar X-ray auroras).

  6. Preliminary Results from a Coordinated Hisaki/Chandra/XMM-Newton Study of the Jovian Aurora and Io Plasma Torus

    Science.gov (United States)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randy; Badman, Sarah Victoria; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen S.; Roediger, Elke; hide

    2014-01-01

    We present preliminary results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus. The data were taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument for roughly 12 hours per observation, and twice by XMM-Newton. The goal of this observational campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  7. Chandra Imaging of the Outer Accretion Flow onto the Black Hole at the Center of the Perseus Cluster

    Science.gov (United States)

    Miller, J. M.; Bautz, M. W.; McNamara, B. R.

    2017-11-01

    Nowhere is black hole feedback seen in sharper relief than in the Perseus cluster of galaxies. Owing to a combination of astrophysical and instrumental challenges, however, it can be difficult to study the black hole accretion that powers feedback into clusters of galaxies. Recent observations with Hitomi have resolved the narrow Fe Kα line associated with accretion onto the black hole in NGC 1275 (3C 84), the active galaxy at the center of Perseus. The width of that line indicates that the fluorescing material is located 6–45 pc from the black hole. Here, we report on a specialized Chandra imaging observation of NGC 1275 that offers a complementary angle. Using a sub-array, sub-pixel event repositioning, and an X-ray “lucky imaging” technique, Chandra imaging suggests an upper limit of about 0.3 arcsec on the size of the Fe Kα emission region, corresponding to ∼98 pc. Both spectroscopy and direct imaging now point to an emission region consistent with an extended molecular torus or disk, potentially available to fuel the black hole. A low X-ray continuum flux was likely measured from NGC 1275; contemporaneously, radio flaring and record-high GeV fluxes were recorded. This may be an example of the correlation between X-ray flux dips and jet activity that is observed in other classes of accreting black holes across the mass scale.

  8. A CHANDRA SNAPSHOT SURVEY FOR 3C RADIO GALAXIES WITH REDSHIFTS BETWEEN 0.3 AND 0.5

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Harris, D. E.; Paggi, A. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Tremblay, G. R. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Muenchen (Germany); Liuzzo, E. [Istituto di Radioastronomia, INAF, via Gobetti 101, I-40129, Bologna (Italy); Bonafede, A. [Hamburger Sternwarte, Universitaet Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2013-05-01

    This paper contains an analysis of short Chandra observations of 19 3C sources with redshifts between 0.3 and 0.5 not previously observed in the X-rays. This sample is part of a project to obtain Chandra data for all of the extragalactic sources in the 3C catalog. Nuclear X-ray intensities as well as any X-ray emission associated with radio jet knots, hotspots, or lobes have been measured in three energy bands: soft, medium, and hard. Standard X-ray spectral analysis for the four brightest nuclei has also been performed. X-ray emission was detected for all the nuclei of the radio sources in the current sample with the exception of 3C 435A. There is one compact steep spectrum source while all the others are FR II radio galaxies. X-ray emission from two galaxy clusters (3C 19 and 3C 320), from six hotspots in four radio galaxies (3C 16, 3C 19, 3C 268.2, 3C 313), and extended X-ray emission on kiloparsec scales in 3C 187 and 3C 313, has been detected.

  9. Chandra observations of comet 2P/Encke 2003 : First detection of a collisionally thin, fast solar wind charge exchange system

    NARCIS (Netherlands)

    Lisse, CM; Christian, DJ; Dennerl, K; Wolk, SJ; Bodewits, Dennis; Hoekstra, Ronnie; Combi, MR; Makinen, T; Dryer, M; Fry, CD; Weaver, H

    2005-01-01

    We report the results of 15 hr of Chandra observations of comet 2P/Encke 2003 on November 24. X-ray emission from comet Encke was resolved on scales of 500-40,000 km, with unusual morphology due to the presence of a low-density, collisionally thin (to charge exchange) coma. A light curve with

  10. Assessing the status of glaciers in part of the Chandra basin, Himachal Himalaya: A multiparametric approach

    Science.gov (United States)

    Garg, Purushottam Kumar; Shukla, Aparna; Tiwari, Reet Kamal; Jasrotia, Avtar Singh

    2017-05-01

    This study investigates the change in multiple glacier parameters of three valley-type glaciers (Sakchum (SC), Chhota Shigri (CS), and Bara Shigri (BS)) located in Chandra basin, Himachal Himalaya, sharing the same climatic regime, and assesses the control of nonclimatic factors on wholesome glacier response. Multitemporal satellite remote sensing data from Landsat-TM/ETM/OLI (1993-2014), and Terra-ASTER (2002-2014) along with an SRTM digital elevation model were used for extraction of the glacier parameters. Results show that while SC and BS retreated (SC: 10.65 ± 2.52 m/y; BS: 15.51 ± 2.52 m/y) and lost area (SC: 0.49 ± 0.0032 km2, BS: 1.18 ± 0.0032 km2), the CS remained relatively stable (retreat rate: 4.06 ± 2.52 m/y, area loss: 0.19 ± 0.0032 km2) during 1993-2014. However, results of surface ice velocities (SIV) change (SC: 24.41%, CS: 21.60%, and BS: 28.49%) and surface elevation change (SC: - 1.22 m/y, CS: - 0.91 m/y and BS: - 1.21 m/y) suggest a comparable slowing down and surface lowering from 2002 to 2014. Debris cover also varied substantially (SC: 30.25%, CS: 11.96%, BS: 19.61%) on these glaciers. Results reveal that higher retreat/deglaciation of glaciers was associated with higher altitudinal range, slow SIV in lower ablation zones (LAZ), and glacier hypsometry. Debris cover on glaciers was found to be controlled by slope, higher deglaciation rates, higher SIV in the upper ablation zone (UAZ) coupled with lower SIV in LAZ and surface lowering. Glacier SIV was primarily governed by slope gradient, differential surface lowering, and size of accumulation zone (ACZ). The SIV results confirm the presence of stagnant zones in the lower ablations of SC (Glacier surface lowering seemed to be influenced by ice-flux, changing spatial distribution of debris cover, presence of supraglacial lakes, and ice cliffs bordering them. Melting around supraglacial lakes and backwasting of ice cliffs may be the prime reasons behind intense mass loss observed in the

  11. The puzzling detection of x-rays from Pluto by Chandra

    Science.gov (United States)

    Lisse, C. M.; McNutt, R. L.; Wolk, S. J.; Bagenal, F.; Stern, S. A.; Gladstone, G. R.; Cravens, T. E.; Hill, M. E.; Kollmann, P.; Weaver, H. A.; Strobel, D. F.; Elliott, H. A.; McComas, D. J.; Binzel, R. P.; Snios, B. T.; Bhardwaj, A.; Chutjian, A.; Young, L. A.; Olkin, C. B.; Ennico, K. A.

    2017-05-01

    Using Chandra ACIS-S, we have obtained low-resolution imaging X-ray spectrophotometry of the Pluto system in support of the New Horizons flyby on 14 July 2015. Observations were obtained in a trial ;seed; campaign conducted in one visit on 24 Feb 2014, and a follow-up campaign conducted soon after the New Horizons flyby that consisted of 3 visits spanning 26 Jul to 03 Aug 2015. In a total of 174 ksec of on-target time, in the 0.31 to 0.60 keV passband, we measured 8 total photons in a co-moving 11 × 11 pixel2 box (the 90% flux aperture determined by observations of fixed background sources in the field) measuring ∼121,000 × 121,000 km2 (or ∼100 × 100 RPluto) at Pluto. No photons were detected from 0.60 to 1.0 keV in this box during the same exposures. Allowing for background, we find a net signal of 6.8 counts and a statistical noise level of 1.2 counts, for a detection of Pluto in this passband at > 99.95% confidence. The Pluto photons do not have the spectral shape of the background, are coincident with a 90% flux aperture co-moving with Pluto, and are not confused with any background source, so we consider them as sourced from the Pluto system. The mean 0.31 - 0.60 keV X-ray power from Pluto is 200 +200/-100 MW, in the middle range of X-ray power levels seen for other known Solar System emission sources: auroral precipitation, solar X-ray scattering, and charge exchange (CXE) between solar wind (SW) ions and atmospheric neutrals. We eliminate auroral effects as a source, as Pluto has no known magnetic field and the New Horizons Alice UV spectrometer detected no airglow from Pluto during the flyby. Nano-scale atmospheric haze particles could lead to enhanced resonant scattering of solar X-rays from Pluto, but the energy signature of the detected photons does not match the solar spectrum and estimates of Pluto's scattered X-ray emission are 2 to 3 orders of magnitude below the 3.9 ± 0.7 × 10-5cps found in our observations. Charge-exchange-driven emission

  12. Radio and Deep Chandra Observations of the Disturbed Cool Core Cluster Abell 133

    Science.gov (United States)

    Randall, S. W.; Clarke, T. E.; Nulsen, P. E. J.; Owers, M. S.; Sarazin, C. L.; Forman, W. R.; Murray, S. S.

    2010-10-01

    We present results based on new Chandra and multi-frequency radio observations of the disturbed cool core cluster Abell 133. The diffuse gas has a complex bird-like morphology, with a plume of emission extending from two symmetric wing-like features. The plume is capped with a filamentary radio structure that has been previously classified as a radio relic. X-ray spectral fits in the region of the relic indicate the presence of either high-temperature gas or non-thermal emission, although the measured photon index is flatter than would be expected if the non-thermal emission is from inverse Compton scattering of the cosmic microwave background by the radio-emitting particles. We find evidence for a weak elliptical X-ray surface brightness edge surrounding the core, which we show is consistent with a sloshing cold front. The plume is consistent with having formed due to uplift by a buoyantly rising radio bubble, now seen as the radio relic, and has properties consistent with buoyantly lifted plumes seen in other systems (e.g., M87). Alternatively, the plume may be a gas sloshing spiral viewed edge-on. Results from spectral analysis of the wing-like features are inconsistent with the previous suggestion that the wings formed due to the passage of a weak shock through the cool core. We instead conclude that the wings are due to X-ray cavities formed by displacement of X-ray gas by the radio relic. The central cD galaxy contains two small-scale cold gas clumps that are slightly offset from their optical and UV counterparts, suggestive of a galaxy-galaxy merger event. On larger scales, there is evidence for cluster substructure in both optical observations and the X-ray temperature map. We suggest that the Abell 133 cluster has recently undergone a merger event with an interloping subgroup, initialing gas sloshing in the core. The torus of sloshed gas is seen close to edge-on, leading to the somewhat ragged appearance of the elliptical surface brightness edge. We show

  13. XMM-Newton and Chandra Observations of the Galaxy Group NGC 5044. 1; Evidence for Limited Multiphase Hot Gas

    Science.gov (United States)

    Buote, David A.; Lewis, Aaron D.; Brighenti, Fabrizio; Mathews, William G.

    2003-01-01

    Using new XMM and Chandra observations, we present an analysis of the temperature structure of the hot gas within a radius of 100 kpc of the bright nearby galaxy group NGC 5044. A spectral deprojection analysis of data extracted from circular annuli reveals that a two-temperature model (2T) of the hot gas is favored over single-phase or cooling flow (M = 4.5 +/- 0.2 solar mass/yr) models within the central approx.30 kpc. Alternatively, the data can be fitted equally well if the temperature within each spherical shell varies continuously from approx.T(sub h) to T(sub c) approx. T(sub h)/2, but no lower. The high spatial resolution of the Chandra data allows us to determine that the temperature excursion T(sub h) approaches T(sub c) required in each shell exceeds the temperature range between the boundaries of the same shell in the best-fitting single-phase model. This is strong evidence for a multiphase gas having a limited temperature range. We do not find any evidence that azimuthal temperature variations within each annulus on the sky can account for the range in temperatures within each shell. We provide a detailed investigation of the systematic errors on the derived spectral models considering the effects of calibration, plasma codes, bandwidth, variable NH, and background rate. We find that the RGS gratings and the EPIC and ACIS CCDs give fully consistent results when the same models are fitted over the same energy ranges for each instrument. The cooler component of the 2T model has a temperature (T(sub c) approx. 0.7 keV) similar to the kinetic temperature of the stars. The hot phase has a temperature (T(sub h) approx. 1.4 keV) characteristic of the virial temperature of the solar mass halo expected in the NGC 5044 group. However, in view of the morphological disturbances and X-ray holes visible in the Chandra image within R approx. equals 10 kpc, bubbles of gas heated to approx.T(sub h) in this region may be formed by intermittent AGN feedback. Some

  14. Suzaku and Chandra observations of the galaxy cluster RXC J1053.7+5453 with a radio relic

    Science.gov (United States)

    Itahana, Madoka; Takizawa, Motokazu; Akamatsu, Hiroki; van Weeren, Reinout J.; Kawahara, Hajime; Fukazawa, Yasushi; Kaastra, Jelle S.; Nakazawa, Kazuhiro; Ohashi, Takaya; Ota, Naomi; Röttgering, Huub J. A.; Vink, Jacco; Zandanel, Fabio

    2017-12-01

    We present the results of Suzaku and Chandra observations of the galaxy cluster RXC J1053.7+5453 (z = 0.0704), which contains a radio relic. The radio relic is located at a distance of ˜540 kpc from the X-ray peak toward the west. We measured the temperature of this cluster for the first time. The resultant temperature in the center is ˜1.3 keV, which is lower than the value expected from the X-ray luminosity-temperature and the velocity dispersion-temperature relations. Though we did not find a significant temperature jump at the outer edge of the relic, our results suggest that the temperature decreases outward across the relic. Assuming the existence of the shock at the relic, its Mach number becomes M ≃ 1.4. A possible spatial variation of Mach number along the relic is suggested. Additionally, a sharp surface brightness edge is found at a distance of ˜160 kpc from the X-ray peak toward the west in the Chandra image. We performed X-ray spectral and surface brightness analyses around the edge with the Suzaku and Chandra data, respectively. The obtained surface brightness and temperature profiles suggest that this edge is not a shock but likely a cold front. Alternatively, it cannot be ruled out that thermal pressure is really discontinuous across the edge. In this case, if the pressure across the surface brightness edge is in equilibrium, other forms of pressure sources, such as cosmic-rays, are necessary. We searched for the non-thermal inverse Compton component in the relic region. Assuming a photon index Γ = 2.0, the resultant upper limit of the flux is 1.9 × 10-14 erg s-1 cm-2 for a 4.50 × 10-3 deg2 area in the 0.3-10 keV band, which implies that the lower limit of magnetic field strength becomes 0.7 μG.

  15. Chandra And HST Observations of Gamma-Ray Blazars: Comparing Jet Emission at Small And Large Scales

    Energy Technology Data Exchange (ETDEWEB)

    Tavecchio, Fabrizio; Maraschi, L.; Wolter, A.; /Brera Observ.; Cheung, C.C.; /KIPAC, Menlo Park; Sambruna, R.M.; /NASA, Goddard; Urry, C.M.; /Yale U., Dept. Astron.

    2007-03-20

    We present new Chandra and HST data for four gamma-ray blazars selected on the basis of radio morphology with the aim of revealing X-ray and optical emission from their jets at large scales. All the sources have been detected. Spectral Energy Distributions of the large scale jets are obtained as well as new X-ray spectra for the blazar cores. Modeling for each object the core (sub-pc scale) and large-scale ({approx}> 100 kpc) jet SEDs, we derive the properties of the same jet at the two scales. The comparison of speeds and powers at different scales supports a simple scenario for the dynamics and propagation of high power relativistic jets.

  16. Contributions of the "Great" X-Ray Observatories (XMM-Newton and Chandra) to Astronomy and Astrophysics

    Science.gov (United States)

    Weisskopf, Martin

    2011-01-01

    NASA s Chandra X-ray Observatory and ESA s XMM-Newton made their first observations over a decade ago. The unprecedented and complementary capabilities of these observatories to detect, image, and measure the energy of cosmic X-rays, achieved less than 50 years after the first detection of an extra-solar X-ray source, represent an increase in sensitivity comparable in going from naked-eye observations to the most powerful optical telescopes over the past 400 years. In this presentation we highlight some of the many discoveries made using these powerful X-ray observatories that have transformed 21st century astronomy. We briefly discuss future prospects for this truly exciting field.

  17. CHANDRA OBSERVATIONS OF COMETS C/2012 S1 (ISON) AND C/2011 L4 (PanSTARRS)

    Energy Technology Data Exchange (ETDEWEB)

    Snios, Bradford; Kharchenko, Vasili [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Lisse, Carey M. [Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Wolk, Scott J. [Chandra X-Ray Observatory Center, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Dennerl, Konrad [Max-Planck-Institut für extraterrestrische Physik, D-85748 Garching (Germany); Combi, Michael R. [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-02-20

    We present our results on the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer (ACIS) observations of the bright Oort Cloud comets C/2012 S1 (ISON) and C/2011 L4 (PanSTARRS). ISON was observed between 2013 October 31–November 06 during variable speed solar wind (SW), and PanSTARRS was observed between 2013 April 17–23 during fast SW. ISON produced an extended parabolic X-ray morphology consistent with a collisionally thick coma, while PanSTARRS demonstrated only a diffuse X-ray-emitting region. We consider these emissions to be from charge exchange (CX) and model each comet's emission spectrum from first principles accordingly. Our model agrees with the observational spectra and also generates composition ratios for heavy, highly charged SW ions interacting with the cometary atmosphere. We compare our derived SW ion compositions to observational data and find a strong agreement between them. These results further demonstrate the utility of CX emissions as a remote diagnostics tool of both astrophysical plasma interaction and SW composition. In addition, we observe potential soft X-ray emissions via ACIS around 0.2 keV from both comets that are correlated in intensity to the hard X-ray emissions between 0.4–1.0 keV. We fit our CX model to these emissions, but our lack of a unique solution at low energies makes it impossible to conclude if they are cometary CX in origin. Finally, we discuss probable emission mechanism sources for the soft X-rays and explore new opportunities these findings present in understanding cometary emission processes via Chandra.

  18. A Joint Chandra and Swift View of the 2015 X-ray Dust-scattering Echo of V404 Cygni

    Science.gov (United States)

    Heinz, S.; Corrales, L.; Smith, R.; Brandt, W. N.; Jonker, P. G.; Plotkin, R. M.; Neilsen, J.

    2016-07-01

    We present a combined analysis of the Chandra and Swift observations of the 2015 X-ray echo of V404 Cygni. Using a stacking analysis, we identify eight separate rings in the echo. We reconstruct the soft X-ray light curve of the 2015 June outburst using the high-resolution Chandra images and cross-correlations of the radial intensity profiles, indicating that about 70% of the outburst fluence occurred during the bright flare at the end of the outburst on MJD 57199.8. By deconvolving the intensity profiles with the reconstructed outburst light curve, we show that the rings correspond to eight separate dust concentrations with precise distance determinations. We further show that the column density of the clouds varies significantly across the field of view, with the centroid of most of the clouds shifted toward the Galactic plane, relative to the position of V404 Cyg, invalidating the assumption of uniform cloud column typically made in attempts to constrain dust properties from light echoes. We present a new XSPEC spectral dust-scattering model that calculates the differential dust-scattering cross section for a range of commonly used dust distributions and compositions and use it to jointly fit the entire set of Swift echo data. We find that a standard Mathis-Rumpl-Nordsieck model provides an adequate fit to the ensemble of echo data. The fit is improved by allowing steeper dust distributions, and models with simple silicate and graphite grains are preferred over models with more complex composition.

  19. PEARS AGN: HST/ACS Grism Spectroscopy of Chandra Deepest Field Optical Counterparts to i = 26AB.

    Science.gov (United States)

    Grogin, Norman A.; Malhotra, S.; Rhoads, J.; Cohen, S.; Hathi, N.; Windhorst, R.; Pirzkal, N.

    2007-12-01

    We investigate sensitive, high spatial resolution, grism spectroscopy for 194 of the 231 X-ray sources within the Chandra Deep Fields North (CDF-N) and South (CDF-S) covered by the PEARS (Probing Evolution And Reionization Spectroscopically) program. These HST/ACS G800L spectra (6000-9500Å) of the faintest known X-ray sources, most of which host moderate-luminosity active galactic nuclei (AGN) at moderate to high redshifts, reach some two magnitudes fainter (to iAB = 26 mag) than currently possible from ground-based observatories. Among our 102 CDF-N spectra are 22 without prior ground-based redshifts, and similarly 22 among the 92 CDF-S spectra. Most of these sources have iAB > 25 mag, making redshift determination challenging even for the sensitive grism observations presented here. We measure redshifts for 52(48) of the CDF-N(S) counterparts, including 5(3) without prior redshift. We compare grism redshift estimates to ground-based redshifts where available, and to PEARS spectro-photometric redshift estimates derived from template-matching to the combination of (U)BViz(JHK) photometry and grism spectra. For the 44 faintest optical counterparts beyond the reach of ground-based spectroscopy, most or all of which are moderate-luminosity AGN at z>1, we also assess whether a lack of spectral features in our grism observations can rule out a Type 1 (unobscured) AGN classification. We simulate an unobscured AGN grism extraction for each of these sources, using the Chandra X-ray flux to appropriately normalize the faintest currently available Type 1 AGN template rest-frame UV spectrum (from the VIMOS VLT Deep Survey) at putative redshifts 11. This work was supported by HST grant GO-10530 from the Space Telescope Science Institute, which is operated by AURA under NASA contract NAS5-26555.

  20. Chandra and XMM-Newton Study of the Supernova Remnant Kes 73 Hosting the Magnetar 1E 1841-045

    Science.gov (United States)

    Kumar, Harsha S.; Safi-Harb, Samar; Slane, Patrick O.; Gotthelf, E. V.

    2014-01-01

    We present a Chandra and XMM-Newton study of the supernova remnant (SNR) Kes 73 hosting the anomalous X-ray pulsar 1E 1841-045. The Chandra image reveals clumpy structures across the remnant with enhanced emission along the western rim. The X-ray emission fills the radio shell and spatially correlates with the infrared image. The global X-ray spectrum is described by a two-component thermal model with a column density N H = 2.6^{+0.4}_{-0.3}\\times1022 cm-2 and a total luminosity of LX = 3.3^{+0.7}_{-0.5}\\times1037 erg s-1 (0.5-10 keV, at an assumed distance of 8.5 kpc). The soft component is characterized by a temperature kTs = 0.5^{+0.1}_{-0.2} keV, a high ionization timescale, and enhanced Si and S abundances, suggesting emission that is dominated by shocked ejecta. The hard component has a temperature kTh = 1.6^{+0.8}_{-0.7} keV, a relatively low ionization timescale, and mostly solar abundances suggesting emission that is dominated by interstellar/circumstellar shocked material. A spatially resolved spectroscopy study reveals no significant variations in the spectral properties. We infer an SNR age ranging between 750 yr and 2100 yr, an explosion energy of 3.0^{+2.8}_{-1.8}\\times1050 erg and a shock velocity of (1.2 ± 0.3)×103 km s-1 (under the Sedov phase assumption). We also discuss the possible scenario for Kes 73 expanding into the late red-supergiant wind phase of its massive progenitor. Comparing the inferred metal abundances to core-collapse nucleosynthesis model yields, we estimate a progenitor mass gsim20 M ⊙, adding a candidate to the growing list of highly magnetized neutron stars proposed to be associated with very massive progenitors.

  1. Les nouveaux résultats Chandra et XMM-Newton concernant les Noyaux Actifs de Galaxies

    Science.gov (United States)

    Porquet, D.

    2001-01-01

    Il s'agit ici d'un apercu des résultats sur les Noyaux Actifs de Galaxies (AGNs) obtenus grace `a la nouvelle génération de satellites X: Chandra & XMM-Newton. Pour la première fois, grace `a leurs caractéristiques instrumentales (sensibilité, résolutions angulaire et spectrale) des images et des spectres de qualité sans précédent sont obtenus dans le domaine des rayons X pour les objets extragalactiques comme les Noyaux Actifs de Galaxies. Notamment une étude spectroscopique fine est dorénavant possible ce qui permet d'appliquer de puissants diagnostics de plasmas comme notamment ceux basés sur les raies des ions héliumoides qui donnent une estimation précise de la densité, de la température, ainsi que la mise en évidence des processus d'ionisation (photoionisation et/ou ionisation collisionnelle) qui dominent dans les plasmas chauds (e.g. "Warm Absorber") des AGNs. La sensibilité de XMM-Newton permet d'étudier les AGNs à très grands redshifts et/ou très fortement absorbés. La résolution angulaire (0.5") de Chandra permet d'étudier séparément les différentes composantes de ces objets: le noyau, le milieu chaud environnant ("Warm Absorber"), les jets, ainsi que le milieu interstellaire et les objets ponctuelles (binaires X, candidats trous noirs, restes de Supernovae,...) de la galaxie hôte. Cette nouvelle ère dans le domaine des rayons X va permettre de fortement contraindre les paramètres physiques, géométriques, dynamiques ainsi que la localisation de la matière accrétante autour des trous noirs supermassifs, dans les différents types d'AGNs (Seyfert, quasars Radio-Loud et Radio-Quiet, noyaux actifs dans les amas de galaxies), en relation avec les autres composantes observées dans les autres domaines de longueurs d'onde (radio, optique, UV, etc...). Ceci s'inscrit dans un objectif plus vaste de compréhension de l'évolution de l'ensemble des galaxies qui pour la plupart semblent contenir un trou noir supermassif en leur

  2. Chandra X-ray observation of the young stellar cluster NGC 3293 in the Carina Nebula Complex

    Science.gov (United States)

    Preibisch, T.; Flaischlen, S.; Gaczkowski, B.; Townsley, L.; Broos, P.

    2017-09-01

    Context. NGC 3293 is a young stellar cluster at the northwestern periphery of the Carina Nebula Complex that has remained poorly explored until now. Aims: We characterize the stellar population of NGC 3293 in order to evaluate key parameters of the cluster population such as the age and the mass function, and to test claims of an abnormal IMF and a deficit of M ≤ 2.5 M⊙ stars. Methods: We performed a deep (70 ks) X-ray observation of NGC 3293 with Chandra and detected 1026 individual X-ray point sources. These X-ray data directly probe the low-mass (M ≤ 2 M⊙) stellar population by means of the strong X-ray emission of young low-mass stars. We identify counterparts for 74% of the X-ray sources in our deep near-infrared images. Results: Our data clearly show that NGC 3293 hosts a large population of ≈solar-mass stars, refuting claims of a lack of M ≤ 2.5 M⊙ stars. The analysis of the color magnitude diagram suggests an age of 8-10 Myr for the low-mass population of the cluster. There are at least 511 X-ray detected stars with color magnitude positions that are consistent with young stellar members within 7 arcmin of the cluster center. The number ratio of X-ray detected stars in the [1-2 ] M⊙ range versus the M ≥ 5 M⊙ stars (known from optical spectroscopy) is consistent with the expectation from a normal field initial mass function. Most of the early B-type stars and ≈20% of the later B-type stars are detected as X-ray sources. Conclusions: Our data shows that NGC 3293 is one of the most populous stellar clusters in the entire Carina Nebula Complex (very similar to Tr 16 and Tr 15; only Tr 14 is more populous). The cluster probably harbored several O-type stars, whose supernova explosions may have had an important impact on the early evolution of the Carina Nebula Complex. The Chandra data described in this paper have been obtained in the open time project with ObsID 16648 (PI: T. Preibisch) ivo://ADS/Sa.CXO#obs/16648.Tables 1-3 are only

  3. CHEERS Results from NGC 3393. II. Investigating the Extended Narrow-line Region Using Deep Chandra Observations and Hubble Space Telescope Narrow-line Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Maksym, W. Peter; Fabbiano, Giuseppina; Elvis, Martin; Karovska, Margarita; Paggi, Alessandro; Raymond, John [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Wang, Junfeng [Department of Astronomy, Physics Building, Xiamen University Xiamen, Fujian, 361005 (China); Storchi-Bergmann, Thaisa, E-mail: walter.maksym@cfa.harvard.edu [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, IF, CP 15051, 91501-970 Porto Alegre, RS (Brazil)

    2017-07-20

    The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study of nearby active galactic nuclei (AGNs) designed to take full advantage of Chandra 's unique angular resolution by spatially resolving feedback signatures and effects. In the second paper of a series on CHEERS target NGC 3393, we examine deep high-resolution Chandra images and compare them with Hubble Space Telescope narrow-line images of [O iii], [S ii], and H α , as well as previously unpublished mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that the S-shaped arms that envelope the nuclear radio outflows extend only ≲0.″2 (≲50 pc) across. The high-resolution multiwavelength data suggest that the extended narrow-line region is a complex multiphase structure in the circumnuclear interstellar medium (ISM). Its ionization structure is highly stratified with respect to outflow-driven bubbles in the bicone and varies dramatically on scales of ∼10 pc. Multiple findings show likely contributions from shocks to the feedback in regions where radio outflows from the AGN most directly influence the ISM. These findings include H α evidence for gas compression and extended MUV emission and are in agreement with existing STIS kinematics. Extended filamentary structure in the X-rays and optical suggests the presence of an undetected plasma component, whose existence could be tested with deeper radio observations.

  4. Some Issues for Cooperative Learning and Intercultural Education: Reflections on Aspects of the Recent Work of Jagdish Gundara

    Science.gov (United States)

    Bash, Leslie

    2014-01-01

    This paper connects the two fields of cooperative learning and intercultural education, focusing on the argument that cooperative learning strategies need to be equipped with intercultural understandings. There is a consideration of assumptions that effective cooperative pedagogical strategies require an engagement with challenging issues related…

  5. Chandra Survey of Nearby Galaxies: A Significant Population of Candidate Central Black Holes in Late-type Galaxies

    Science.gov (United States)

    She, Rui; Ho, Luis C.; Feng, Hua

    2017-06-01

    Based on the Chandra data archive as of 2016 March, we have identified 314 candidate active galactic nuclei in 719 galaxies located closer than 50 Mpc, among them late-type galaxies (Hubble types Sc and later) that previously had been classified from optical observations as containing star-forming (H II) nuclei. These late-type galaxies comprise a valuable subsample to search for low-mass (≲ {10}6 {M}⊙ ) central black holes. For the sample as a whole, the overall dependence of the fraction of active nuclei on galaxy type and nuclear spectral classification is consistent with previous results based on optical surveys. We detect 51 X-ray cores among the 163 H II nuclei and estimate that, very conservatively, ˜74% of them with luminosities above 1038 {erg} {{{s}}}-1 are not contaminated by X-ray binaries; the fraction increases to ˜92% for X-ray cores with a luminosity of 1039 {erg} {{{s}}}-1 or higher. This allows us to estimate a black hole occupation fraction of ≳ 21% in these late-type galaxies, many of which are bulgeless.

  6. Biodiversity and Indigenous Uses of Medicinal Plant in the Chandra Prabha Wildlife Sanctuary, Chandauli District, Uttar Pradesh

    Directory of Open Access Journals (Sweden)

    Maurya Santosh Kumar

    2015-01-01

    Full Text Available Conventional medicines are very important part of Indian culture. In this study the outcome of two-year study of ethnomedicinal uses of plants in Chandra Prabha Wildlife Sanctuary (CPWLS and nearby area is reported. Information related to different plants which are used by local community in the treatment of many common diseases and well-being in the area was collected. Data on the use of medicinal plants were collected using structured interview of about 122 participants and thorough observations and conversations with local communities. Approximately 100 plants belonging to 43 families used by the local healers were reported in this study. The plant species with the highest fidelity level (Fl were Holarrhena antidysenterica, Lawsonia inermis, Gymnema sylvestre, Dalbergia sissoo, Cassia fistula Linn., Butea monosperma (Lam. Kuntze., Boerhaavia diffusa Linn., Albizia lebbeck Benth., Aegle marmelos Correa., Sphaeranthus indicus Linn., and Solanum surattense Burm. f. The most frequent ailments reported were hepatitis, jaundice, constipation, and skin and urinary problems. The parts of the plants most frequently used were fruit, roots, and whole plants (17% followed by leaves (16% and bark (15%. This study presents new research efforts and perspectives on the search for new drugs based on local uses of medicinal plants.

  7. Determinations Of The Radii, Redshifts, And Atmospheric Compositions Of Neutron Stars From Modeling Their Chandra X-ray Spectra

    CERN Document Server

    Stage, M D

    2003-01-01

    Fitting the X-ray spectra of thermal radiation from neutron stars with realistic atmosphere models provides a way to place constraints on their radii, surface gravities and compositions, and to test general relativity in the strong field limit. Such determinations allow us to constrain the equation of state of nuclear matter. I present fits which constrain the radii and surface compositions of two neutron stars, using high quality Chandra X-ray Observatory observations of the point source in the Cassiopeia A supernova remnant (Cas A XPS), and the isolated neutron star RX J1856.5-3754. I apply models calculated with advanced versions of the ATM model atmosphere code developed by Madej and Joss for neutron- star atmospheres composed of hydrogen, hydrogen-helium, iron, or a silicon to iron mixture. The results, taken assuming a typical value of 1.4 solar masses, show that the X-ray emission is generated from hot spot regions of scale size ∼3–4 km, on stars of intrinsic radius 9 and 12.5 km. Thi...

  8. Constraining the Accretion Geometry of the Intermediate Polar EX Hya Using NuSTAR, Swift, and Chandra Observations

    Science.gov (United States)

    Luna, G. J. M.; Mukai, K.; Orio, M.; Zemko, P.

    2018-01-01

    In magnetically accreting white dwarfs, the height above the white dwarf surface where the standing shock is formed is intimately related with the accretion rate and the white dwarf mass. However, it is difficult to measure. We obtained new data with NuSTAR and Swift that, together with archival Chandra data, allow us to constrain the height of the shock in the intermediate polar EX Hya. We conclude that the shock has to form at least at a distance of about one white dwarf radius from the surface in order to explain the weak Fe Kα 6.4 keV line, the absence of a reflection hump in the high-energy continuum, and the energy dependence of the white dwarf spin pulsed fraction. Additionally, the NuSTAR data allowed us to measure the true, uncontaminated hard X-ray (12-40 keV) flux, whose measurement was contaminated by the nearby galaxy cluster Abell 3528 in non-imaging X-ray instruments.

  9. Around 200 new X-ray binary IDs from 13 YR of Chandra observations of the M31 center

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, R.; Garcia, M. R.; Primini, F. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Li, Z. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Baganoff, F. K. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Murray, S. S. [Johns Hopkins University, Baltimore, MD (United States)

    2014-01-01

    We have created 0.3-10 keV, 13 yr, unabsorbed luminosity lightcurves for 528 X-ray sources in the central 20' of M31. We have 174 Chandra observations spaced at ∼1 month intervals due to our transient monitoring program, deeper observations of the M31 nucleus, and some public data from other surveys. We created 0.5-4.5 keV structure functions (SFs) for each source for comparison with the ensemble SF of active galactic nuclei (AGN). We find 220 X-ray sources with luminosities ≳10{sup 35} erg s{sup –1} that have SFs with significantly more variability than the ensemble AGN SF, and which are likely X-ray binaries (XBs). A further 30 X-ray sources were identified as XBs using other methods. We therefore have 250 probable XBs in total, including ∼200 new identifications. This result represents great progress over the ∼50 XBs and ∼40 XB candidates previously identified out of the ∼2000 X-ray sources within the D {sub 25} region of M31; it also demonstrates the power of SF analysis for identifying XBs in external galaxies. We also identify a new transient black hole candidate, associated with the M31 globular cluster B128.

  10. FRONTIER FIELDS CLUSTERS: DEEP CHANDRA OBSERVATIONS OF THE COMPLEX MERGER MACS J1149.6+2223

    Energy Technology Data Exchange (ETDEWEB)

    Ogrean, G. A.; Weeren, R. J. van; Jones, C.; Forman, W.; Andrade-Santos, F.; Murray, S. S.; Nulsen, P.; Bulbul, E.; Kraft, R.; Randall, S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Dawson, W. A. [Lawrence Livermore National Lab, 7000 East Avenue, Livermore, CA 94550 (United States); Golovich, N. [University of California, One Shields Avenue, Davis, CA 95616 (United States); Roediger, E. [Astronomy and Astrophysics Section, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Zitrin, A.; Sayers, J. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Goulding, A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Mroczkowski, T. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Bonafede, A. [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany); Churazov, E., E-mail: gogrean@cfa.harvard.edu [Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany); and others

    2016-03-10

    The Hubble Space Telescope Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. We present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z  =  0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the line of sight. The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. If the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster.

  11. Chandra and Suzaku Follow-up Observations of Hard X-ray Selected AGN in the UDIS

    Science.gov (United States)

    Virani, Shanil N.; Urry, C. M.; Treister, E.; Schawinski, K.; Maccarone, T. J.; Beckmann, V.; Coppi, P.

    2010-01-01

    We carried out a 3 Megasecond Ultra-Deep INTEGRAL Survey (UDIS) to define a faint hard X-ray-selected AGN sample, unbiased by even the heaviest obscuration. The space density of AGN that are Compton-thick (NH>1024 cm-2) remains unknown even though it has been suggested they could nearly equal the space density of less obscured supermassive black holes. In the Ultra-Deep INTEGRAL Survey, one of the deepest surveys of the hard X-ray sky ever done, we detect 15 AGN some of which are detected in the hard X-rays for the first time. In order to measure the obscuration and the high-energy reflection component for these sources, we obtained follow-up observations with Chandra and Suzaku. Here we present X-ray spectra for all 15 AGN, including the inferred distribution of absorbing column densities. Measurement and modeling of the X-ray background provides at best an integral and degenerate constraint on AGN populations, which only weakly constrains the most obscured objects as they make only a minor contribution to the background. Direct detection of heavily obscured objects by surveys like UDIS is thus the only way to obtain a true census of their population.

  12. THE CHANDRA MULTI-WAVELENGTH PROJECT: OPTICAL SPECTROSCOPY AND THE BROADBAND SPECTRAL ENERGY DISTRIBUTIONS OF X-RAY-SELECTED AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Trichas, Markos; Green, Paul J.; Aldcroft, Tom; Kim, Dong-Woo; Mossman, Amy [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Silverman, John D. [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan); Barkhouse, Wayne [Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202 (United States); Cameron, Robert A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Constantin, Anca [Department of Physics and Astronomy, James Madison University, PHCH, Harrisonburg, VA 22807 (United States); Ellison, Sara L. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1 (Canada); Foltz, Craig [Division of Astronomical Sciences, National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230 (United States); Haggard, Daryl [Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Jannuzi, Buell T. [NOAO, Kitt Peak National Observatory, Tucson, AZ 85726 (United States); Marshall, Herman L. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Perez, Laura M. [Department of Astronomy, California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 (United States); Romero-Colmenero, Encarni [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Ruiz, Angel [Osservatorio Astronomico di Brera-INAF, Milan (Italy); Smith, Malcolm G., E-mail: mtrichas@cfa.harvard.edu [Cerro Tololo Interamerican Observatory, La Serena (Chile); and others

    2012-06-01

    From optical spectroscopy of X-ray sources observed as part of the Chandra Multi-wavelength Project (ChaMP), we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow-up using the FLWO/1.5 m, SAAO/1.9 m, WIYN 3.5 m, CTIO/4 m, KPNO/4 m, Magellan/6.5 m, MMT/6.5 m, and Gemini/8 m telescopes, and from archival Sloan Digital Sky Survey (SDSS) spectroscopy. We classify the optical counterparts as 50% broad-line active galactic nuclei (AGNs), 16% emission line galaxies, 14% absorption line galaxies, and 20% stars. We detect QSOs out to z {approx} 5.5 and galaxies out to z {approx} 3. We have compiled extensive photometry, including X-ray (ChaMP), ultraviolet (GALEX), optical (SDSS and ChaMP-NOAO/MOSAIC follow-up), near-infrared (UKIDSS, Two Micron All Sky Survey, and ChaMP-CTIO/ISPI follow-up), mid-infrared (WISE), and radio (FIRST and NVSS) bands. Together with our spectroscopic information, this enables us to derive detailed spectral energy distributions (SEDs) for our extragalactic sources. We fit a variety of template SEDs to determine bolometric luminosities, and to constrain AGNs and starburst components where both are present. While {approx}58% of X-ray Seyferts (10{sup 42} erg s{sup -1} < L{sub 2-10keV} <10{sup 44} erg s{sup -1}) require a starburst event (>5% starburst contribution to bolometric luminosity) to fit observed photometry only 26% of the X-ray QSO (L{sub 2-10keV} >10{sup 44} erg s{sup -1}) population appear to have some kind of star formation contribution. This is significantly lower than for the Seyferts, especially if we take into account torus contamination at z > 1 where the majority of our X-ray QSOs lie. In addition, we observe a rapid drop of the percentage of starburst contribution as X-ray luminosity increases. This is consistent with the quenching of star formation by powerful QSOs, as predicted by the merger model, or with a time lag between the peak of star formation and QSO

  13. Chandra survey of nearby highly inclined disk galaxies - IV. New insights into the working of stellar feedback

    Science.gov (United States)

    Wang, Q. Daniel; Li, Jiangtao; Jiang, Xiaochuan; Fang, Taotao

    2016-04-01

    Galaxy evolution is regulated by the interplay between galactic discs and their surrounding medium. We study this interplay by examining how the galactic coronal emission efficiency of stellar feedback depends on the (surface and specific) star formation rates (SFRs) and other parameters for a sample of 52 Chandra-observed nearby highly inclined disc galaxies. We first measure the star-forming galactic disc sizes, as well as the SFRs of these galaxies, using data from the Wide-Field Infrared Survey Explorer, and then show that (1) the specific 0.5-2 keV luminosity of the coronal emission correlates with the specific SFR in a sub-linear fashion: on average, LX/LK∝(SFR/M*)Γ with Γ = 0.29 ± 0.12; (2) the efficiency of the emission LX/SFR decreases with increasing surface SFR (ISFR; Γ = -0.44 ± 0.12); and (3) the characteristic temperature of the X-ray-emitting plasma weakly correlates with ISFR (Γ = 0.08 ± 0.04). These results, somewhat surprising and anti-intuitive, suggest that (i) the linear correlation between LX and SFR, as commonly presented, is largely due to the correlation of these two parameters with galaxy mass; (ii) much of the mechanical energy from stellar feedback likely drives global outflows with little X-ray cooling and with a mass-loading efficiency decreasing fast with increasing ISFR (Γ ≲ -0.5); (iii) these outflows heat and inflate the medium around the galactic disks of massive galaxies, reducing its radiative cooling rate, whereas for relatively low-mass galaxies, the energy in the outflows is probably dissipated in regions far away from the galactic discs.

  14. The Outer Limits of Galaxy Clusters: Observations to the Virial Radius with Suzaku, XMM,and Chandra

    Science.gov (United States)

    Miller, Eric D.; Bautz, Marshall; George, Jithin; Mushotzky, Richard; Davis, David; Henry, J. Patrick

    2012-01-01

    The outskirts of galaxy clusters, near the virial radius, remain relatively unexplored territory and yet are vital to our understanding of cluster growth, structure, and mass. In this presentation, we show the first results from a program to constrain the sate of the outer intra-cluster medium (ICM) in a large sample of galaxy clusters, exploiting the strengths of three complementary X-ray observatories: Suzaku (low, stable background), XMM-Newton (high sensitivity),and Chandra (good spatial resolution). By carefully combining observations from the cluster core to beyond r200, we are able to identify and reduce systematic uncertainties that would impede our spatial and spectral analysis using a single telescope. Our sample comprises nine clusters at z is approximately 0.1-0.2 fully covered in azimuth to beyond r200, and our analysis indicates that the ICM is not in hydrostatic equilibrium in the cluster outskirts, where we see clear azimuthal variations in temperature and surface brightness. In one of the clusters, we are able to measure the diffuse X-ray emission well beyond r200, and we find that the entropy profile and the gas fraction are consistent with expectations from theory and numerical simulations. These results stand in contrast to recent studies which point to gas clumping in the outskirts; the extent to which differences of cluster environment or instrumental effects factor in this difference remains unclear. From a broader perspective, this project will produce a sizeable fiducial data set for detailed comparison with high-resolution numerical simulations.

  15. Deepest View of AGN X-Ray Variability with the 7 Ms Chandra Deep Field-South Survey

    Science.gov (United States)

    Zheng, X. C.; Xue, Y. Q.; Brandt, W. N.; Li, J. Y.; Paolillo, M.; Yang, G.; Zhu, S. F.; Luo, B.; Sun, M. Y.; Hughes, T. M.; Bauer, F. E.; Vito, F.; Wang, J. X.; Liu, T.; Vignali, C.; Shu, X. W.

    2017-11-01

    We systematically analyze the X-ray variability of active galactic nuclei (AGNs) in the 7 Ms Chandra Deep Field-South survey. On the longest timescale (≈17 years), we find only a weak (if any) dependence of X-ray variability amplitudes on energy bands or obscuration. We use four different power spectral density (PSD) models to fit the anticorrelation between normalized excess variance ({σ }{nxv}2) and luminosity, and obtain a best-fit power-law index β ={1.16}-0.05+0.05 for the low-frequency part of the AGN PSD. We also divide the whole light curves into four epochs in order to inspect the dependence of {σ }{nxv}2 on these timescales, finding an overall increasing trend. The analysis of these shorter light curves also infers a β of ∼1.3 that is consistent with the above-derived β, which is larger than the frequently assumed value of β =1. We then investigate the evolution of {σ }{nxv}2. No definitive conclusion is reached because of limited source statistics, but if present, the observed trend goes in the direction of decreasing AGN variability at fixed luminosity toward high redshifts. We also search for transient events and find six notable candidate events with our considered criteria. Two of them may be a new type of fast transient events, one of which is reported here for the first time. We therefore estimate a rate of fast outbursts ={1.0}-0.7+1.1× {10}-3 {{galaxy}}-1 {{yr}}-1 and a tidal disruption event (TDE) rate ={8.6}-4.9+8.5× {10}-5 {{galaxy}}-1 {{yr}}-1 assuming the other four long outbursts to be TDEs.

  16. CHANDRA OBSERVATIONS OF NGC 4342, AN OPTICALLY FAINT, X-RAY GAS-RICH EARLY-TYPE GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, Akos; Forman, William R.; Kraft, Ralph P.; Jones, Christine; Randall, Scott W.; Li Zhiyuan; Nulsen, Paul E. J.; Vikhlinin, Alexey [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Blom, Christina [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Zhang Zhongli; Zhuravleva, Irina; Churazov, Eugene [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-str. 1, 85748 Garching (Germany); Schindler, Sabine, E-mail: abogdan@cfa.harvard.edu [Institut fuer Astrophysik, Leopold-Franzens Universitaet Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria)

    2012-08-10

    Chandra x-ray observations of NGC 4342, a low-stellar mass (M{sub K} = -22.79 mag) early-type galaxy, show luminous, diffuse x-ray emission originating from hot gas with temperature of kT {approx} 0.6 keV. The observed 0.5-2 keV band luminosity of the diffuse x-ray emission within the D{sub 25} ellipse is L{sub 0.5-2keV} = 2.7 Multiplication-Sign 10{sup 39} erg s{sup -1}. The hot gas has a significantly broader distribution than the stellar light, and shows strong hydrodynamic disturbances with a sharp surface brightness edge to the northeast and a trailing tail. We identify the edge as a cold front and conclude that the distorted morphology of the hot gas is produced by ram pressure as NGC 4342 moves through external gas. From the thermal pressure ratios inside and outside the cold front, we estimate the velocity of NGC 4342 and find that it moves supersonically (M {approx} 2.6) toward the northeast. Outside the optical extent of the galaxy, we detect {approx}17 bright (L{sub 0.5-8keV} > or approx. 3 x 10{sup 37} erg s{sup -1}) excess x-ray point sources. The excess sources are presumably LMXBs located in metal-poor globular clusters (GCs) in the extended dark matter halo of NGC 4342. Based on the number of excess sources and the average frequency of bright LMXBs in GCs, we estimate that NGC 4342 may host roughly 850-1700 GCs. In good agreement with this, optical observations hint that NGC 4342 may harbor 1200 {+-} 500 GCs. This number corresponds to a GC specific frequency of S{sub N} = 19.9 {+-} 8.3, which is among the largest values observed in full-size galaxies.

  17. A FLUX-LIMITED SAMPLE OF z {approx} 1 Ly{alpha} EMITTING GALAXIES IN THE CHANDRA DEEP FIELD SOUTH ,

    Energy Technology Data Exchange (ETDEWEB)

    Barger, A. J.; Wold, I. G. B. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Cowie, L. L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2012-04-20

    We describe a method for obtaining a flux-limited sample of Ly{alpha} emitters from Galaxy Evolution Explorer (GALEX) grism data. We show that the multiple GALEX grism images can be converted into a three-dimensional (two spatial axes and one wavelength axis) data cube. The wavelength slices may then be treated as narrowband images and searched for emission-line galaxies. For the GALEX NUV grism data, the method provides a Ly{alpha} flux-limited sample over the redshift range z = 0.67-1.16. We test the method on the Chandra Deep Field South field, where we find 28 Ly{alpha} emitters with faint continuum magnitudes (NUV > 22) that are not present in the GALEX pipeline sample. We measure the completeness by adding artificial emitters and measuring the fraction recovered. We find that we have an 80% completeness above a Ly{alpha} flux of 10{sup -15} erg cm{sup -2} s{sup -1}. We use the UV spectra and the available X-ray data and optical spectra to estimate the fraction of active galactic nuclei in the selection. We report the first detection of a giant Ly{alpha} blob at z < 1, though we find that these objects are much less common at z = 1 than at z = 3. Finally, we compute limits on the z {approx} 1 Ly{alpha} luminosity function and confirm that there is a dramatic evolution in the luminosity function over the redshift range z = 0-1.

  18. FRONTIER FIELDS CLUSTERS: CHANDRA AND JVLA VIEW OF THE PRE-MERGING CLUSTER MACS J0416.1-2403

    Energy Technology Data Exchange (ETDEWEB)

    Ogrean, G. A.; Weeren, R. J. van; Jones, C.; Nulsen, P. E. J.; Forman, W.; Murray, S. S.; Randall, S.; Kraft, R.; David, L.; Andrade-Santos, F.; Goulding, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Clarke, T. E.; Mroczkowski, T. [U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Sayers, J.; Zitrin, A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Pandey-Pommier, M. [Centre de Recherche Astrophysique de Lyon, Observatoire de Lyon, 9 av Charles André, F-69561 Saint Genis Laval Cedex (France); Churazov, E. [Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741, Garching (Germany); Bonafede, A. [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112 21029 Hamburg (Germany); Merten, J. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Umetsu, K., E-mail: gogrean@cfa.harvard.edu [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); and others

    2015-10-20

    Merging galaxy clusters leave long-lasting signatures on the baryonic and non-baryonic cluster constituents, including shock fronts, cold fronts, X-ray substructure, radio halos, and offsets between the dark matter (DM) and the gas components. Using observations from Chandra, the Jansky Very Large Array, the Giant Metrewave Radio Telescope, and the Hubble Space Telescope, we present a multiwavelength analysis of the merging Frontier Fields cluster MACS J0416.1-2403 (z = 0.396), which consists of NE and SW subclusters whose cores are separated on the sky by ∼250 kpc. We find that the NE subcluster has a compact core and hosts an X-ray cavity, yet it is not a cool core. Approximately 450 kpc south–southwest of the SW subcluster, we detect a density discontinuity that corresponds to a compression factor of ∼1.5. The discontinuity was most likely caused by the interaction of the SW subcluster with a less massive structure detected in the lensing maps SW of the subcluster's center. For both the NE and the SW subclusters, the DM and the gas components are well-aligned, suggesting that MACS J0416.1-2403 is a pre-merging system. The cluster also hosts a radio halo, which is unusual for a pre-merging system. The halo has a 1.4 GHz power of (1.3 ± 0.3) × 10{sup 24} W Hz{sup −1}, which is somewhat lower than expected based on the X-ray luminosity of the cluster if the spectrum of the halo is not ultra-steep. We suggest that we are either witnessing the birth of a radio halo, or have discovered a rare ultra-steep spectrum halo.

  19. Chandra/HETGS Spectroscopy of the Galactic Black Hole GX 339-4: A Relativistic Iron Line and Evidence for a Seyfert-like Warm Absorber

    OpenAIRE

    Miller, J. M.; Raymond, J; Fabian, A. C.; Homan, J.; Nowak, M A; Wijnands, R.; van der Klis, M.; Belloni, T.; Tomsick, J. A.; Smith, D M; Charles, P.A.; Lewin, W.H.G.

    2003-01-01

    We observed the Galactic black hole GX 339-4 with the Chandra High Energy Transmission Grating Spectrometer (HETGS) for 75 ksec during the decline of its 2002-2003 outburst. The sensitivity of this observation provides an unprecedented glimpse of a Galactic black hole at about a tenth of the luminosity of the outburst peak. The continuum spectrum is well described by a model consisting of multicolor disk blackbody (kT = 0.6 keV) and power-law (Gamma = 2.5) components. X-ray reflection models ...

  20. Observations of the Crab Nebula with the Chandra X-Ray Observatory During the Gamma-Ray Flare of 2011 April

    Science.gov (United States)

    Weisskopf, Martin C.

    2012-01-01

    Recently, using the AGILE and Fermi satellites, gamma-ray flares have been discovered from the direction of the Crab Nebula (Tavani et al. 2011, Abdo et al. 2011). We have been using the Chandra X-Ray observatory to monitor the Crab on a monthly cadence since just after the 2010 September gamma-ray flare. We were fortunate to trigger series of pre-planned target of opportunity observations during the 2011 April flare. We present the results of these observations and address some implications both for now and for the future.

  1. PHOTOIONIZATION MODELING OF OXYGEN K ABSORPTION IN THE INTERSTELLAR MEDIUM: THE CHANDRA GRATING SPECTRA OF XTE J1817-330

    Energy Technology Data Exchange (ETDEWEB)

    Gatuzz, E.; Mendoza, C. [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), P.O. Box 20632, Caracas 1020A (Venezuela, Bolivarian Republic of); Garcia, J.; Lohfink, A. [Department of Astronomy and Maryland Astronomy Center for Theory and Computation, University of Maryland, College Park, MD 20742 (United States); Kallman, T. R.; Witthoeft, M. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bautista, M. A. [Department of Physics, Western Michigan University, Kalamazoo, MI 49008 (United States); Palmeri, P.; Quinet, P., E-mail: egatuzz@ivic.gob.ve, E-mail: claudio@ivic.gob.ve, E-mail: javier@astro.umd.edu, E-mail: alohfink@astro.umd.edu, E-mail: timothy.r.kallman@nasa.gov, E-mail: michael.c.witthoeft@nasa.gov, E-mail: manuel.bautista@wmich.edu, E-mail: palmeri@umons.ac.be, E-mail: quinet@umons.ac.be [Astrophysique et Spectroscopie, Universite de Mons-UMONS, B-7000 Mons (Belgium)

    2013-05-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N{sub H} = 1.38 {+-} 0.01 Multiplication-Sign 10{sup 21} cm{sup -2}; an ionization parameter of log {xi} = -2.70 {+-} 0.023; an oxygen abundance of A{sub O}= 0.689{sup +0.015}{sub -0.010}; and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval, a rescaling with the revision by Asplund et al. yields A{sub O}=0.952{sup +0.020}{sub -0.013}, a value close to solar that reinforces the new standard. We identify several atomic absorption lines-K{alpha}, K{beta}, and K{gamma} in O I and O II and K{alpha} in O III, O VI, and O VII-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n > 2 associated with ISM cold absorption.

  2. New Constraints on Dark Energy from Chandra X-rayObservations of the Largest Relaxed Galaxy Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Allen, S.W.; Rapetti, D.A.; /KIPAC, Menlo Park; Schmidt, R.W.; /Heidelberg, Astron. Rechen Inst.; Ebeling, H.; /Inst. Astron., Honolulu; Morris, G.; /KIPAC, Menlo Park; Fabian, A.C.; /Cambridge U., Inst. of Astron.

    2007-06-06

    We present constraints on the mean matter density, {Omega}{sub m}, dark energy density, {Omega}{sub DE}, and the dark energy equation of state parameter, w, using Chandra measurements of the X-ray gas mass fraction (fgas) in 42 hot (kT > 5keV), X-ray luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.05 < z < 1.1. Using only the fgas data for the 6 lowest redshift clusters at z < 0.15, for which dark energy has a negligible effect on the measurements, we measure {Omega}{sub m}=0.28{+-}0.06 (68% confidence, using standard priors on the Hubble Constant, H{sub 0}, and mean baryon density, {Omega}{sub b}h{sup 2}). Analyzing the data for all 42 clusters, employing only weak priors on H{sub 0} and {Omega}{sub b}h{sup 2}, we obtain a similar result on {Omega}{sub m} and detect the effects of dark energy on the distances to the clusters at {approx}99.99% confidence, with {Omega}{sub DE}=0.86{+-}0.21 for a non-flat LCDM model. The detection of dark energy is comparable in significance to recent SNIa studies and represents strong, independent evidence for cosmic acceleration. Systematic scatter remains undetected in the f{sub gas} data, despite a weighted mean statistical scatter in the distance measurements of only {approx}5%. For a flat cosmology with constant w, we measure {Omega}{sub m}=0.28{+-}0.06 and w=-1.14{+-}0.31. Combining the fgas data with independent constraints from CMB and SNIa studies removes the need for priors on {Omega}{sub b}h{sup 2} and H{sub 0} and leads to tighter constraints: {Omega}{sub m}=0.253{+-}0.021 and w=-0.98{+-}0.07 for the same constant-w model. More general analyses in which we relax the assumption of flatness and/or allow evolution in w remain consistent with the cosmological constant paradigm. Our analysis includes conservative allowances for systematic uncertainties. The small systematic scatter and tight constraints bode well for future dark energy studies using the f{sub gas} method.

  3. Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium:. [The Chandra Grating Spectra of XTE J1817-330

    Science.gov (United States)

    Gatuzz, E.; Garcia, J.; Mendoza, C.; Kallman, T. R.; Witthoeft, M.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 Angstrom broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 Angstroms) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the xstar code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N(sub H) = 1.38 +/- 0.01 × 10(exp 21) cm(exp -2); an ionization parameter of log xi = -2.70 +/- 0.023; an oxygen abundance of A(sub O) = 0.689 (+0.015/-0.010); and ionization fractions of O(sub I)/O = 0.911, O(sub II)/O = 0.077, and O(sub III)/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse & Sauval, a rescaling with the revision by Asplund et al. yields A(sub O) = 0.952(+0.020/-0.013), a value close to solar that reinforces the new standard.We identify several atomic absorption lines-K(alpha), K(beta), and K(gamma) in O(sub I) and O(sub II) and K(alpha) in O(sub III), O(sub VI), and O(sub VII)-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated with ISM cold absorption.

  4. Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium: The Chandra Grating Spectra of XTE J1817-330

    Science.gov (United States)

    Gatuzz, E.; Garcia, J.; Menodza, C.; Kallman, T. R.; Witthoeft, M.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra towards the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pileup effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain: a column density of N(sub H) = 1.38 +/- 0.01 x 10(exp 21) cm(exp -2); ionization parameter of log xi = .2.70 +/- 0.023; oxygen abundance of A(sub O) = 0.689(exp +0.015./-0.010); and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval (1998), a rescaling with the revision by Asplund et al. (2009) yields A(sub O) = 0.952(exp +0.020/-0.013, a value close to solar that reinforces the new standard. We identify several atomic absorption lines.K-alpha , K-beta, and K-gamma in O I and O II; and K-alpha in O III, O VI, and O VII--last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated to ISM cold absorption.

  5. Immediate effect of chandra nadi pranayama (left unilateral forced nostril breathing on cardiovascular parameters in hypertensive patients

    Directory of Open Access Journals (Sweden)

    Ananda Balayogi Bhavanani

    2012-01-01

    Full Text Available Introduction : Recent studies have reported differential physiological and psychological effects produced by exclusive right and left nostril breathing and clinical research is required to prove immediate and sustained efficacy of these techniques in various psychosomatic conditions such as hypertension (HT. The present study was designed to determine immediate effects of 27 rounds of exclusive left nostril breathing, a yogic pranayama technique known as chandra nadi pranayama (CNP on cardiovascular parameters in patients of essential HT. Materials and Methods : Twenty two patients of essential HT under regular standard medical management were individually taught to perform CNP by a qualified yoga instructor with a regularity of 6 breaths/min throughout a performance of 27 rounds of CNP. Pre and post intervention heart rate (HR and blood pressure (BP measurements were recorded using non-invasive semi-automatic BP monitor and Students t test for paired data used to determine significant differences. Results : Twenty seven rounds of CNP produced an immediate decrease in all the measured cardiovascular parameters with the decrease in HR, systolic pressure (SP, pulse pressure, rate-pressure product and double product being statistically significant. Further, gender-based sub-analysis of our data revealed that our male participants evidenced significant reductions in HR and SP with an insignificant decrease in diastolic pressure, while in female participants only HR decreased significantly with an insignificant decrease in SP. Discussion and Conclusion : It is concluded that CNP is effective in reducing HR and SP in hypertensive patients on regular standard medical management. To the best of our knowledge, there are no previously published reports on immediate effects of left UFNB in patients of HT and ours is the first to report on this beneficial clinical effect. This may be due to a normalization of autonomic cardiovascular rhythms with increased

  6. AN ALMA SURVEY OF SUBMILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: NEAR-INFRARED MORPHOLOGIES AND STELLAR SIZES

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chian-Chou; Smail, Ian; Swinbank, A. M.; Simpson, J. M.; Ma, Cheng-Jiun; Alexander, D. M.; Danielson, A. L. R.; Edge, A. C. [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Biggs, A. D.; Ivison, R. J. [European Southern Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching (Germany); Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5 (Canada); Coppin, K. E. K. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Dannerbauer, H. [Institut für Astrophysik, Universität Wien, Türkenschanzstraße 17, A-1180 Wien (Austria); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Karim, A. [Argelander-Institute for Astronomy, Bonn University, Auf dem Hügel 71, D-53121 Bonn (Germany); Menten, Karl M. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Schinnerer, E.; Walter, F. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Wardlow, J. L. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); and others

    2015-02-01

    We analyze Hubble Space Telescope WFC3/H {sub 160}-band observations of a sample of 48 Atacama Large Millimeter/submillimeter Array detected submillimeter galaxies (SMGs) in the Extended Chandra Deep Field South field, to study their stellar morphologies and sizes. We detect 79% ± 17% of the SMGs in the H {sub 160}-band imaging with a median sensitivity of 27.8 mag, and most (80%) of the nondetections are SMGs with 870 μm fluxes of S {sub 870} < 3 mJy. With a surface brightness limit of μ {sub H} ∼ 26 mag arcsec{sup –2}, we find that 82% ± 9% of the H {sub 160}-band-detected SMGs at z = 1-3 appear to have disturbed morphologies, meaning they are visually classified as either irregulars or interacting systems, or both. By determining a Sérsic fit to the H {sub 160} surface brightness profiles, we derive a median Sérsic index of n = 1.2 ± 0.3 and a median half-light radius of r{sub e} = 4.4{sub −0.5}{sup +1.1} kpc for our SMGs at z = 1-3. We also find significant displacements between the positions of the H {sub 160} component and 870 μm emission in these systems, suggesting that the dusty starburst regions and less-obscured stellar distribution are not colocated. We find significant differences in the sizes and the Sérsic index between our z = 2-3 SMGs and z ∼ 2 quiescent galaxies, suggesting that a major transformation of the stellar light profile is needed in the quenching processes if SMGs are progenitors of the red-and-dead z ∼ 2 galaxies. Given the short-lived nature of SMGs, we postulate that the majority of the z = 2-3 SMGs with S {sub 870} ≳ 2 mJy are early/mid-stage major mergers.

  7. Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

    Science.gov (United States)

    Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, Jhn E.; Tramper, Frank

    2009-01-01

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary s focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c(sup 2).

  8. Stripped Elliptical Galaxies as Probes of ICM Physics. III. Deep Chandra Observations of NGC 4552: Measuring the Viscosity of the Intracluster Medium

    Science.gov (United States)

    Kraft, R. P.; Roediger, E.; Machacek, M.; Forman, W. R.; Nulsen, P. E. J.; Jones, C.; Churazov, E.; Randall, S.; Su, Y.; Sheardown, A.

    2017-10-01

    We present results from a deep (200 ks) Chandra observation of the early-type galaxy NGC 4552 (M89), which is falling into the Virgo cluster. Previous shallower X-ray observations of this galaxy showed a remnant gas core, a tail to the South of the galaxy, and twin “horns” attached to the northern edge of the gas core. In our deeper data, we detect a diffuse, low surface brightness extension to the previously known tail, and measure the temperature structure within the tail. We combine the deep Chandra data with archival XMM-Newton observations to put a strong upper limit on the diffuse emission of the tail out to a large distance (10× the radius of the remnant core) from the galaxy center. In our two previous papers, we presented the results of hydrodynamical simulations of ram pressure stripping specifically for M89 falling into the Virgo cluster and investigated the effect of intracluster medium (ICM) viscosity. In this paper, we compare our deep data with our specifically tailored simulations and conclude that the observed morphology of the stripped tail in NGC 4552 is most similar to the inviscid models. We conclude that, to the extent the transport processes can be simply modeled as a hydrodynamic viscosity, the ICM viscosity is negligible. More generally, any micro-scale description of the transport processes in the high-β plasma of the cluster ICM must be consistent with the efficient mixing observed in the stripped tail on macroscopic scales.

  9. The 0.3-30 Kev Spectra Of Powerful Starburst Galaxies: Nustar And Chandra Observations Of Ngc 3256 And Ngc 3310

    DEFF Research Database (Denmark)

    Lehmer, B. D.; Tyler, J. B.; Hornschemeier, A. E.

    2015-01-01

    We present nearly simultaneous Chandra and NuSTAR observations of two actively star-forming galaxies within 50 Mpc: NGC 3256 and NGC 3310. Both galaxies are significantly detected by both Chandra and NuSTAR, which together provide the first-ever spectra of these two galaxies spanning 0.3-30 ke...... with equivalent measurements for nearby star-forming galaxies M83 and NGC 253, we analyze the star formation rate (SFR) normalized spectra of these starburst galaxies. The spectra of all four galaxies show sharply declining power-law slopes at energies above 3-6 keV primarily due to ULX populations. Our......-Eddington accreting ULXs that have been studied individually in a targeted NuSTAR ULX program. We also find that NGC 3310 exhibits a factor of ≈3-10 elevation of X-ray emission over the other star-forming galaxies due to a corresponding overabundance of ULXs. We argue that the excess of ULXs in NGC 3310 is most...

  10. Venkattaraman, Prof. Chandra

    Indian Academy of Sciences (India)

    Date of birth: 3 June 1963. Specialization: Aerosol Science & Engineering, Environmental & Climate Science, Atmospheric Science Address: Department of Chemical Engineering, Indian Institute of Technology, Powai, Mumbai 400 076, Mahrashtra Contact: Office: (022) 2576 7224. Residence: (022) 2576 8224

  11. Lakhotia, Prof. Subhash Chandra

    Indian Academy of Sciences (India)

    Ph.D. (Calcutta), FNA, FNASc. Date of birth: 4 October 1945. Specialization: Ayurvedic Biology, Cytogenetics, Gene Expression, Stress Biology and Molecular Biology Address: INSA Senior Scientist, Department of Zoology, Banaras Hindu University, Varanasi 221 005, U.P. Contact: Office: (0542) 236 8145, (0542) 236 8457

  12. Chance and Chandra

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... ... especially for systems having a dominant central mass. After this prelude, a hypothetical form of bosonic dark matter with a simple but nontrivial statistical mechanics is discussed. This makes for a number of eminently falsifiable predictions, including some exotic consequences for dynamical friction.

  13. Ranu, Prof. Brindaban Chandra

    Indian Academy of Sciences (India)

    mediated Supported Metal and Metal Nanoparticle-catalysed Reactions, Organic Synthesis Address: Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, W.B.. Contact: Office: (033) ...

  14. Maheshwari, Prof. Satish Chandra

    Indian Academy of Sciences (India)

    Delhi), FNA, FNASc. Date of birth: 4 October 1933. Specialization: Physiology & Biochemistry of Plant Growth & Development and Plant Molecular Biology Address: 251/56, Prathap Enclave, Haldighati Road, Jaipur 302 033, Rajasthan Contact ...

  15. Kundu, Dr Gopal Chandra

    Indian Academy of Sciences (India)

    Date of birth: 2 November 1959. Specialization: Tumour Biology, Regulation of Gene Expression, Angiogenesis and Nanomedicine Address: Scientist G, National Centre for Cell Science, NCCS Complex, Pune 411 007, Maharashtra Contact: Office: (020) 2570 8104. Mobile: 94225 06548. Fax: (020) 2569 2259

  16. Sir Prafulla Chandra Ray

    Indian Academy of Sciences (India)

    which led to it are thus described in the opening paragraph of the first communication on the subject. "Having recently had occasion to prepare mercurous nitrate in quantity by the action of dilute acid [nitric acid] in the cold mercury, I was rather struck by the appearance of a yellow crystalline deposit. At first sight it was taken ...

  17. Nayak, Prof. Nabeen Chandra

    Indian Academy of Sciences (India)

    Date of birth: 31 January 1931. Specialization: Pathology, Oncology and Liver Diseases Address: Adviser, Department of Pathology, Sir Gangaram Hospital, Rajinder Nagar, New Delhi 110 060, U.T.. Contact: Mobile: 90138 20308. Email: dr_ncnayak@yahoo.com. YouTube; Twitter; Facebook; Blog ...

  18. Chandra, Prof. Nagasuma

    Indian Academy of Sciences (India)

    . Date of birth: 16 May 1965. Specialization: Protein Structure, Algorithm Development, Systems Biology, Bioinformatics, Genomic & Clinical Data Analysis Address: Department of Biochemistry, Indian Institute of Science, Bengaluru 560 012, ...

  19. Chance and Chandra

    Indian Academy of Sciences (India)

    cores of dwarf galaxies. More complex and extended profiles can be obtained if the DM has a finite temperature, as discussed below, or where it has not yet reached thermal or even virial equilibrium. It was argued by Peebles [29] and Goodman [30] that if present-day repulsive dark mat- ter (hereafter RDM) derives from a ...

  20. Agrawal, Prof. Prahlad Chandra

    Indian Academy of Sciences (India)

    Date of birth: 15 April 1941. Specialization: X-ray Astronomy and Experimental High Energy Astrophysics Address: 405, Vigyan Scientists' CHS, Plot No. 23, Sector 17, Vashi, Navi Mumbai 400 703, Maharashtra Contact: Office: (022) 2653 0230. Residence: (022) 2789 9894. Mobile: 98673 43442

  1. Chandra and XMM-Newton observations of the low-luminosity X-ray pulsators SAX J1324.4−6200 and SAX J1452.8−5949

    NARCIS (Netherlands)

    Kaur, R.; Wijnands, R.; Patruno, A.; Testa, V.; Israel, G.; Degenaar, N.; Paul, B.; Kumar, B.

    2009-01-01

    We present results from our Chandra and XMM-Newton observations of two low-luminosity X-ray pulsators SAX J1324.4-6200 and SAX J1452.8-5949 which have spin periods of 172 and 437 s, respectively. The XMM-Newton spectra for both sources can be fitted well with a simple power-law model of photon

  2. Monitoring Chandra Observations of the Quasi-persistent Neutron Star X-Ray Transient MXB 1659-29 in Quiescence: The Cooling Curve of the Heated Neutron Star Crust

    NARCIS (Netherlands)

    Wijnands, R.A.D.; Homan, J.; Miller, J.M.; Lewin, W.H.G.

    2004-01-01

    We have observed the quasi-persistent neutron star X-ray transient and eclipsing binary MXB 1659-29 in quiescence on three occasions with Chandra. The purpose of our observations was to monitor the quiescent behavior of the source after its last prolonged (~2.5 yr) outburst that ended in 2001

  3. Chandra/High Energy Transmission Grating Spectrometer Spectroscopy of the Galactic Black Hole GX 339-4: A Relativistic Iron Emission Line and Evidence for a Seyfert-like Warm Absorber

    NARCIS (Netherlands)

    Miller, J.M.; Raymond, J.; Fabian, A.C.; Homan, J.; Nowak, M.A.; Wijnands, R.A.D.; van der Klis, M.; Belloni, T.; Tomsick, J.A.; Smith, D.M.; Charles, P.A.; Lewin, W.H.G.

    2004-01-01

    We observed the Galactic black hole GX 339-4 with the Chandra High Energy Transmission Grating Spectrometer (HETGS) for 75 ks during the decline of its 2002-2003 outburst. The sensitivity of this observation provides an unprecedented glimpse of a Galactic black hole at about a tenth of the

  4. Implications of the Detection of X-rays From Pluto by Chandra for Its Solar Wind - Neutral Atmosphere Interaction

    Science.gov (United States)

    Lisse, C. M.

    2016-12-01

    Using the Chandra X-Ray Observatory, we have obtained low-resolution imaging X-ray spectrophotometry of the Pluto system in support of the New Horizons (NH) flyby. In a total of 174 ksec of on-target time, we measured 8 photons from 0.31 to 0.60 keV in a co-moving 11 x 11 pixel2 box (the 90% flux aperture for fixed background sources in the field) measuring 121,000 x 121,000 km2 (or 100 x 100 RPluto) at Pluto. The Pluto photons do not have the spectral shape of the background, are coincident with a 90% flux aperture co-moving with Pluto, and are not confused with any background source, so we consider them as sourced from the Pluto system. Allowing for background, we find a net signal of 6.8 counts and a statistical noise level of 1.2 counts, for a detection of Pluto at > 99.95%. The mean 0.31 - 0.60 keV X-ray power from Pluto is 200 +200/-100 MW, in the middle range of X-ray power levels seen for other known solar system emission sources: auroral precipitation, solar X-ray scattering, and charge exchange (CXE) between solar wind (SW) ions and atmospheric neutrals. We eliminate auroral effects as a source, as Pluto has no known magnetic field and the NH/Alice UV spectrometer detected no airglow from Pluto during the flyby. Atmospheric haze particles could produce resonant scattering of solar X-rays from Pluto, but the energy signature of the detected photons does not match the solar spectrum and estimates of Pluto's scattered X-ray emission are 2 to 3 orders of magnitude lower than seen in our observations. CXE-driven emission from hydrogenic and heliogenic SW carbon, nitrogen, and oxygen ions can produce the energy signature seen, and the 6 x 1025 neutral gas escape rate from Pluto deduced from NH data (Gladstone et al. 2016) can support the 3.0 +3.0/-1.5 x 1024 X-ray photons/s emission rate required by our observations. Using the SW proton density and speed measured by the NH/SWAP instrument in the vicinity of Pluto at the time of the photon emissions, we find a

  5. XMM-Newton and Chandra observations of the ejecta-dominated mixed-morphology galactic supernova remnant G352.7–0.1

    Energy Technology Data Exchange (ETDEWEB)

    Pannuti, Thomas G.; Napier, Jared P. [Space Science Center, Department of Earth and Space Sciences, 235 Martindale Drive, Morehead State University, Morehead, KY 40351 (United States); Kargaltsev, Oleg; Brehm, Derek, E-mail: t.pannuti@moreheadstate.edu, E-mail: jpnapier@moreheadstate.edu, E-mail: kargaltsev@gwu.edu, E-mail: brehm.derek@gmail.com [Department of Physics, 308 Samson Hall, George Washington University, Washington, DC 20052 (United States)

    2014-02-20

    We present a spatial and spectral X-ray analysis of the Galactic supernova remnant (SNR) G352.7–0.1 using archival data from observations made with the XMM-Newton X-ray Observatory and the Chandra X-ray Observatory. Prior X-ray observations of this SNR had revealed a thermal center-filled morphology that contrasts with a shell-like radio morphology, thus establishing G352.7–0.1 as a member of the class of Galactic SNRs known as mixed-morphology SNRs (MMSNRs). Our study confirms that the X-ray emission comes from the SNR interior and must be ejecta dominated. Spectra obtained with XMM-Newton may be fit satisfactorily with a single thermal component (namely a non-equilibrium ionization component with enhanced abundances of silicon and sulfur). In contrast, spectra extracted by Chandra from certain regions of the SNR cannot always be fit by a single thermal component. For those regions, a second thermal component with solar abundances or two thermal components with different temperatures and thawed silicon and sulfur abundances (respectively) can generate a statistically acceptable fit. We argue that the former scenario is more physically plausible: on the basis of parameters of our spectral fits, we calculate physical parameters including X-ray emitting mass (∼45 M {sub ☉} for solar abundances). We find no evidence for overionization in the X-ray emitting plasma associated with the SNR: this phenomenon has been seen in other MMSNRs. We have conducted a search for a neutron star within the SNR by using a hard (2-10 keV) Chandra image but could not identify a firm candidate. We also present (for the first time) the detection of infrared emission from this SNR as detected at 24 μm by the MIPS on board Spitzer. Finally, we discuss the properties of G352.7–0.1 in the context of other ejecta-dominated MMSNRs.

  6. THE 0.3–30 keV SPECTRA OF POWERFUL STARBURST GALAXIES: NuSTAR AND CHANDRA OBSERVATIONS OF NGC 3256 AND NGC 3310

    Energy Technology Data Exchange (ETDEWEB)

    Lehmer, B. D.; Wik, D. R.; Yukita, M. [The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Tyler, J. B.; Hornschemeier, A. E.; Ptak, A.; Zhang, W. W. [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Antoniou, V.; Zezas, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Boggs, S.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Harrison, F. A. [Caltech Division of Physics, Mathematics and Astronomy, Pasadena (United States); Maccarone, T. J. [Department of Physics, Texas Tech University, Lubbock, TX 79409 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2015-06-10

    We present nearly simultaneous Chandra and NuSTAR observations of two actively star-forming galaxies within 50 Mpc: NGC 3256 and NGC 3310. Both galaxies are significantly detected by both Chandra and NuSTAR, which together provide the first-ever spectra of these two galaxies spanning 0.3–30 keV. The X-ray emission from both galaxies is spatially resolved by Chandra; we find that hot gas dominates the E < 1–3 keV emission while ultraluminous X-ray sources (ULXs) provide majority contributions to the emission at E > 1–3 keV. The NuSTAR galaxy-wide spectra of both galaxies follow steep power-law distributions with Γ ≈ 2.6 at E > 5–7 keV. Using new and archival Chandra data, we search for signatures of heavily obscured or low luminosity active galactic nuclei (AGNs). We find that both NGC 3256 and NGC 3310 have X-ray detected sources coincident with nuclear regions; however, the steep NuSTAR spectra of both galaxies restricts these sources to be either low luminosity AGNs (L{sub 2−10} {sub keV}/L{sub Edd} ≲ 10{sup −5}) or non-AGNs in nature (e.g., ULXs or crowded X-ray sources that reach L{sub 2−10} {sub keV} ∼ 10{sup 40} erg s{sup −1} cannot be ruled out). Combining our constraints on the 0.3–30 keV spectra of NGC 3256 and NGC 3310 with equivalent measurements for nearby star-forming galaxies M83 and NGC 253, we analyze the star formation rate (SFR) normalized spectra of these starburst galaxies. The spectra of all four galaxies show sharply declining power-law slopes at energies above 3–6 keV primarily due to ULX populations. Our observations therefore constrain the average spectral shape of galaxy-wide populations of luminous accreting binaries (i.e., ULXs). Interestingly, despite a completely different galaxy sample selection, emphasizing here a range of SFRs and stellar masses, these properties are similar to those of super-Eddington accreting ULXs that have been studied individually in a targeted NuSTAR ULX program. We also find that

  7. XV and XVI SERC Main Schools in Theoretical High Energy Physics held at the Saha Institute of Nuclear Physics and Harish-Chandra Research Institute

    CERN Document Server

    2005-01-01

    Current research in High Energy Physics focuses on a number of enigmatic issues that go beyond the very successful Standard Model of particle physics. Among these are the problem of neutrino mass, the (as yet) unobserved Higgs particle, the quark-gluon plasma, quantum aspects of gravity, and the so--called hierarchy problem. Satisfactory resolution of these important questions will take much research effort in both theory and experiment. The Science & Engineering Research Council, Department of Science & Technology has sponsored a series of SERC Schools in Theoretical High Energy Physics over the past several years, to provide instruction and training to graduate students working for research degrees. This book is an outcome of the schools held at the Saha Institute of Nuclear Physics, Kolkata in 2000, and at the Harish-Chandra Research Institute, Allahabad in 2001. Based on lectures by active researchers in the field---Rajiv Gavai, Debashis Ghoshal, Dileep Jatkar, Anjan Joshipura, Biswarup Mukhopadhy...

  8. IACHEC CROSS-CALIBRATION OF CHANDRA , NuSTAR , SWIFT , SUZAKU , XMM-NEWTON WITH 3C 273 ANDPKS 2155-304

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Kristin K.; Forster, Karl [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Beardmore, Andrew P.; Page, Kim L. [X-ray and Observational Astronomy Group, Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Guainazzi, Matteo [Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, 3-1-1, Yoshinodai, Sagamihara, Kanagawa, 252-5201 (Japan); Marshall, Herman L.; Miller, Eric D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Stuhlinger, Martin [European Space Astronomy Centre (ESAC), P.O. Box 78, E-28691 Villanueva de la Caada, Madrid (Spain)

    2017-01-01

    On behalf of the International Astronomical Consortium for High Energy Calibration, we present results from the cross-calibration campaigns in 2012 on 3C 273 and in 2013 on PKS 2155-304 between the then active X-ray observatories Chandra , NuSTAR , Suzaku , Swift, and XMM-Newton . We compare measured fluxes between instrument pairs in two energy bands, 1–5 keV and 3–7 keV, and calculate an average cross-normalization constant for each energy range. We review known cross-calibration features and provide a series of tables and figures to be used for evaluating cross-normalization constants obtained from other observations with the above mentioned observatories.

  9. The NuSTAR Extragalactic Surveys: Initial Results and Catalog from the Extended Chandra Deep Field South

    DEFF Research Database (Denmark)

    Mullaney, J. R.; Del-Moro, A.; Aird, J.

    2015-01-01

    that are detected in both bands span the range 0.39–1.7, corresponding to a photon index range of G » 0.5-2.3, with a median photon index of G = 1.70 ± 0.52. Theredshifts of the 49 sources in our main sample span the range z = 0.21-2.7, and their rest-frame 10–40 keVluminosities (derived from the observed 8–24 ke......V fluxes) span the range L10 40 keV (0.7 300) 10 erg s» - ´ 43 1 -- ,sampling below the “knee” of the X-ray luminosity function out to z ~ 0.8-1. Finally, we identify oneNuSTAR source that has neither a Chandra nor an XMM-Newton counterpart, but that shows evidence of nuclearactivity at infrared...

  10. The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy

    Science.gov (United States)

    Danehkar, Ashkbiz; Nowak, Michael A.; Lee, Julia C.; Kriss, Gerard A.; Young, Andrew J.; Hardcastle, Martin J.; Chakravorty, Susmita; Fang, Taotao; Neilsen, Joseph; Rahoui, Farid; Smith, Randall K.

    2018-02-01

    We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create XSTAR photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately ‑17,300 km s‑1 (outflow redshift z out ∼ ‑0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter {log}ξ ∼ 2.9 {erg} {{{s}}}-1 {cm} and column density {log}{N}{{H}}∼ 21.5 {{cm}}-2. This corresponds to a stable region of the absorber’s thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately ‑16,980 km s‑1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.

  11. X-ray Properties of the z ~ 4.5 Lyα Emitters in the Chandra Deep Field South Region

    Science.gov (United States)

    Zheng, Z. Y.; Wang, J. X.; Finkelstein, S. L.; Malhotra, S.; Rhoads, J. E.; Finkelstein, K. D.

    2010-07-01

    We report the first X-ray detection of Lyα emitters (LAEs) at redshift z ~ 4.5. One source (J033127.2-274247) is detected in the Extended Chandra Deep Field-South (ECDF-S) X-ray data and has been spectroscopically confirmed as a z = 4.48 quasar with LX = 4.2 × 1044 erg s-1. The single detection gives an Lyα quasar density of ~ 2.7+6.2 -2.2 × 10-6 Mpc-3, consistent with the X-ray luminosity function of quasars. Another 22 LAEs in the central Chandra Deep Field-South region are not detected individually, but their co-added counts yield an S/N = 2.4 (p = 99.83%) detection at soft band, with an effective exposure time of ~36 Ms. Further analysis of the equivalent width (EW) distribution shows that all the signals come from 12 LAE candidates with EWrestLAEs. If the average X-ray emission is due to star formation, it corresponds to a star formation rate (SFR) of 3%-10%. However, our upper limit on the SFR X is ~7 times larger than the upper limit on SFR X on z ~ 3.1 LAEs in the same field and at least 30 times higher than the SFR estimated from Lyα emission. From the average X-ray-to-Lyα line ratio, we estimate that fewer than 3.2% (6.3%) of our LAEs could be high-redshift type 1 (type 2) active galactic nuclei (AGNs) and those hidden AGNs likely show low rest-frame EWs.

  12. An alma survey of submillimeter galaxies in the extended Chandra deep field-south: The agn fraction and X-ray properties of submillimeter galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. X.; Brandt, W. N.; Luo, B. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Smail, I.; Alexander, D. M.; Danielson, A. L. R.; Karim, A.; Simpson, J. M.; Swinbank, A. M. [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Hodge, J. A.; Walter, F. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Lehmer, B. D. [The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Wardlow, J. L. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Xue, Y. Q. [Key Laboratory for Research in Galaxies and Cosmology, Center for Astrophysics, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Chapman, S. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Coppin, K. E. K. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Dannerbauer, H. [Universität Wien, Institute für Astrophysik, Türkenschanzstraße 17, 1180 Wien (Austria); De Breuck, C. [European Southern Observatory, Karl-Schwarzschild Straße 2, D-85748 Garching (Germany); Menten, K. M. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Van der Werf, P., E-mail: xxw131@psu.edu, E-mail: niel@astro.psu.edu [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

    2013-12-01

    The large gas and dust reservoirs of submillimeter galaxies (SMGs) could potentially provide ample fuel to trigger an active galactic nucleus (AGN), but previous studies of the AGN fraction in SMGs have been controversial largely due to the inhomogeneity and limited angular resolution of the available submillimeter surveys. Here we set improved constraints on the AGN fraction and X-ray properties of the SMGs with Atacama Large Millimeter/submillimeter Array (ALMA) and Chandra observations in the Extended Chandra Deep Field-South (E-CDF-S). This study is the first among similar works to have unambiguously identified the X-ray counterparts of SMGs; this is accomplished using the fully submillimeter-identified, statistically reliable SMG catalog with 99 SMGs from the ALMA LABOCA E-CDF-S Submillimeter Survey. We found 10 X-ray sources associated with SMGs (median redshift z = 2.3), of which eight were identified as AGNs using several techniques that enable cross-checking. The other two X-ray detected SMGs have levels of X-ray emission that can be plausibly explained by their star formation activity. Six of the eight SMG-AGNs are moderately/highly absorbed, with N {sub H} > 10{sup 23} cm{sup –2}. An analysis of the AGN fraction, taking into account the spatial variation of X-ray sensitivity, yields an AGN fraction of 17{sub −6}{sup +16}% for AGNs with rest-frame 0.5-8 keV absorption-corrected luminosity ≥7.8 × 10{sup 42} erg s{sup –1}; we provide estimated AGN fractions as a function of X-ray flux and luminosity. ALMA's high angular resolution also enables direct X-ray stacking at the precise positions of SMGs for the first time, and we found four potential SMG-AGNs in our stacking sample.

  13. Tracing the Mass-Dependent Star Formation History of Late-Type Galaxies using X-ray Emission: Results from the CHANDRA Deep Fields

    Science.gov (United States)

    Lehmer, B.D; Brandt, W.N.; Schneider, D.P.; Steffen, A.T.; Alexander, D.M.; Bell, E.F.; Hornschemeier, A.E.; McIntosh, D.H.; Bauer, F.E.; Gilli, R.; hide

    2008-01-01

    We report on the X-ray evolution over the last approx.9 Gyr of cosmic history (i.e., since z = 1.4) of late-type galaxy populations in the Chandra Deep Field-North and Extended Chandra Deep Field-South (CDF-N and E-CDF-S. respectively; jointly CDFs) survey fields. Our late-type galaxy sample consists of 2568 galaxies. which were identified using rest-frame optical colors and HST morphologies. We utilized X-ray stacking analyses to investigate the X-ray emission from these galaxies, emphasizing the contributions from normal galaxies that are not dominated by active galactic nuclei (AGNs). Over this redshift range, we find significant increases (factors of approx. 5-10) in the X-ray-to-optical mean luminosity ratio (L(sub x)/L(sub B)) and the X-ray-to-stellar-mass mean ratio (L(sub x)/M(sub *)) for galaxy populations selected by L(sub B) and M(sub *), respectively. When analyzing galaxy samples selected via SFR, we find that the mean X-ray-to-SFR ratio (L(sub x)/SFR) is consistent with being constant over the entire redshift range for galaxies with SFR = 1-100 Solar Mass/yr, thus demonstrating that X-ray emission can be used as a robust indicator of star-formation activity out to z approx. 1.4. We find that the star-formation activity (as traced by X-ray luminosity) per unit stellar mass in a given redshift bin increases with decreasing stellar mass over the redshift range z = 0.2-1, which is consistent with previous studies of how star-formation activity depends on stellar mass. Finally, we extend our X-ray analyses to Lyman break galaxies at z approx. 3 and estimate that L(sub x)/L(sub B) at z approx. 3 is similar to its value at z = 1.4.

  14. The 7 Ms Chandra Deep Field-South Survey: Cosmic Black-Hole Growth is Mainly Linked to Host-Galaxy Stellar Mass

    Science.gov (United States)

    Brandt, W. Niel; Yang, Guang; Chen, Chien-Ting; Vito, Fabio

    2017-08-01

    The Chandra exposure on the Chandra Deep Field-South (CDF-S) has recently been increased to 7 Ms, allowing unmatched X-ray and multiwavelength characterization of cosmic black-hole growth in active galactic nuclei (AGNs). We have used these data to investigate the dependence of black-hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M*) at z = 0.5-2. Our sample consists of 18,000 galaxies with SFR and M* measurements, and we use sample-mean BHAR for these galaxies to approximate their long-term average BHAR. Our sample-mean BHARs are derived from the CDF-S observations via both direct spectral analysis and stacking. The average BHAR is correlated positively with both SFR and M*, and the BHAR-SFR and BHAR-M* relations can both be described acceptably by linear models with a slope of unity. However, according to partial-correlation analyses, BHAR is correlated more strongly with M* than SFR. This result indicates that M* is the primary host-galaxy property related to black-hole growth, and the well-known BHAR-SFR relation is largely a secondary effect due to the "star-forming main sequence". Among our sources, massive galaxies have significantly higher BHAR/SFR ratios than less-massive galaxies, indicating the former have higher black-hole fueling efficiency and/or higher SMBH occupation fraction than the latter; e.g., the deeper potential wells in higher mass galaxies may promote black-hole accretion and counteract AGN/supernova feedback. Our results can naturally explain the observed proportionality between MBH and M* for local giant ellipticals, and suggest their MBH/M* ratios are higher than those of local star-forming galaxies. Finally, prospects for extending this work will be discussed; e.g., by further investigating the redshift evolution of the primary BHAR-M* relation and measuring this relation for even higher values of M*, above ~ 1011 solar masses, using wide-field X-ray surveys.

  15. New Chandra observations of the jet in 3C273. 1. Softer X-ray than radio spectra and the X-ray emission mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Jester, Sebastian; /Fermilab; Harris, D.E.; /Smithsonian Astrophys. Observ.; Marshall, H.L.; /MIT, MKI; Meisenheimer, K.; /Heidelberg, Max Planck Inst. Astron.

    2006-05-01

    The jet in 3C273 is a high-power quasar jet with radio, optical and X-ray emission whose size and brightness allow a detailed study of the emission processes acting in it. We present deep Chandra observations of this jet and analyze the spectral properties of the jet emission from radio through X-rays. We find that the X-ray spectra are significantly softer than the radio spectra in all regions of the bright part of the jet except for the first bright ''knot A'', ruling out a model in which the X-ray emission from the entire jet arises from beamed inverse-Compton scattering of cosmic microwave background photons in a single-zone jet flow. Within two-zone jet models, we find that a synchrotron origin for the jet's X-rays requires fewer additional assumptions than an inverse-Compton model, especially if velocity shear leads to efficient particle acceleration in jet flows.

  16. Harnessing the full power of the widest Chandra field: average accretion rates of black holes in SDSS galaxies through X-ray stacking

    Science.gov (United States)

    Goulding, Andy D.; Greene, Jenny E.; Hickox, Ryan C.; Alexander, David M.; Forman, William R.; Jones, Christine; Lehmer, Bret

    2017-08-01

    Galaxy-scale bars are expected to provide an effective means for driving material towards the central region in spiral galaxies, and possibly feeding supermassive black holes (BHs). I will present our latest results on a statistically-complete study of the effect of bars on average BH accretion. From a well-selected sample of over 50,000 spiral galaxies extracted from the Sloan Digital Sky Survey, we separate those sources considered to contain galaxy-scale bars from those that do not. Using the first 16 years worth of data taken by the Chandra X-ray Observatory, we identify X-ray luminous AGN and perform the widest-area X-ray stacking analysis to date on the remaining X-ray undetected sources. Through our X-ray stacking, we derive a time-averaged look at accretion for galaxies at fixed stellar mass and star formation rate, finding that the average nuclear accretion rates of galaxies with bar structures are fully consistent with those lacking bars, and robustly concluding that large-scale bars have little or no effect on the average growth of BHs in nearby (z < 0.15) galaxies over gigayear timescales.

  17. The Taiwan ECDFS Near-Infrared Survey: Ultra-deep J and KS Imaging in the Extended Chandra Deep Field-South

    Science.gov (United States)

    Hsieh, Bau-Ching; Wang, Wei-Hao; Hsieh, Chih-Chiang; Lin, Lihwai; Yan, Haojing; Lim, Jeremy; Ho, Paul T. P.

    2012-12-01

    We present ultra-deep J and KS imaging observations covering a 30' × 30' area of the Extended Chandra Deep Field-South (ECDFS) carried out by our Taiwan ECDFS Near-Infrared Survey (TENIS). The median 5σ limiting magnitudes for all detected objects in the ECDFS reach 24.5 and 23.9 mag (AB) for J and KS , respectively. In the inner 400 arcmin2 region where the sensitivity is more uniform, objects as faint as 25.6 and 25.0 mag are detected at 5σ. Thus, this is by far the deepest J and KS data sets available for the ECDFS. To combine TENIS with the Spitzer IRAC data for obtaining better spectral energy distributions of high-redshift objects, we developed a novel deconvolution technique (IRACLEAN) to accurately estimate the IRAC fluxes. IRACLEAN can minimize the effect of blending in the IRAC images caused by the large point-spread functions and reduce the confusion noise. We applied IRACLEAN to the images from the Spitzer IRAC/MUSYC Public Legacy in the ECDFS survey (SIMPLE) and generated a J+KS -selected multi-wavelength catalog including the photometry of both the TENIS near-infrared and the SIMPLE IRAC data. We publicly release the data products derived from this work, including the J and KS images and the J+KS -selected multi-wavelength catalog.

  18. A multiwavelength study of the massive GLIMPSE-C01 cluster with the Hubble Space Telescope and Chandra X-ray Observatory

    Science.gov (United States)

    Hare, Jeremy; Kargaltsev, Oleg; Rangelov, Blagoy

    2018-01-01

    GLIMPSE-C01 is a heavily obscured, intermediate-age cluster that has been suggested to be one of the most massive clusters in the Milky Way. We observed GLIMPSE-C01 with both HST WFC3 IR and UVIS to look for NIR/Optical counterparts to the X-ray sources discovered by the Chandra X-ray Observatory. We present the results of the HST observations, analyze the stellar population of the cluster, and classify X-ray sources using multiwavelength information. We identify several X-ray binary candidates including one likely CV and one likely LMXB. The multi-band HST data also constrain the somewhat controversial distance and age of the cluster. The impact of confusion, affecting the WFC3/IR images of the cluster's core, is also evaluated. The presented observations and their analyses demonstrate the limitations of current instruments and the potential of JWST's superior angular resolution and sensitivety in crowded fields. We also discuss the potential of HST and JWST for multiwavelength X-ray source classification.

  19. Deep Chandra observations of HCG 16. II. The development of the intra-group medium in a spiral-rich group

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, E.; Vrtilek, J. M.; David, L. P.; Zezas, A.; Nulsen, P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Giacintucci, S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Ponman, T. J.; Raychaudhury, S. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Mamon, G. A. [Institut d' Astrophysique de Paris (UMR 7095 CNRS and UMPC), 98 bis Bd Arago, F-75014 Paris (France)

    2014-10-01

    We use a combination of deep Chandra X-ray observations and radio continuum imaging to investigate the origin and current state of the intra-group medium (IGM) in the spiral-rich compact group HCG 16. We confirm the presence of a faint (L {sub X,} {sub bolo} = 1.87{sub −0.66}{sup +1.03}×10{sup 41} erg s{sup –1}), low-temperature (0.30{sub −0.05}{sup +0.07} keV) IGM extending throughout the ACIS-S3 field of view, with a ridge linking the four original group members and extending to the southeast, as suggested by previous ROSAT and XMM-Newton observations. This ridge contains 6.6{sub −3.3}{sup +3.9}× 10{sup 9} M {sub ☉} of hot gas and is at least partly coincident with a large-scale H I tidal filament, indicating that the IGM in the inner part of the group is highly multi-phase. We present evidence that the group is not yet virialized, and show that gas has probably been transported from the starburst winds of NGC 838 and NGC 839 into the surrounding IGM. Considering the possible origin of the IGM, we argue that material ejected by galactic winds may have played a significant role, contributing 20%-40% of the observed hot gas in the system.

  20. Deep Chandra Observations of HCG 16. II. The Development of the Intra-group Medium in a Spiral-rich Group

    Science.gov (United States)

    O'Sullivan, E.; Vrtilek, J. M.; David, L. P.; Giacintucci, S.; Zezas, A.; Ponman, T. J.; Mamon, G. A.; Nulsen, P.; Raychaudhury, S.

    2014-10-01

    We use a combination of deep Chandra X-ray observations and radio continuum imaging to investigate the origin and current state of the intra-group medium (IGM) in the spiral-rich compact group HCG 16. We confirm the presence of a faint (L X, bolo = 1.87+1.03-0.66×1041 erg s-1), low-temperature (0.30+0.07-0.05 keV) IGM extending throughout the ACIS-S3 field of view, with a ridge linking the four original group members and extending to the southeast, as suggested by previous ROSAT and XMM-Newton observations. This ridge contains 6.6+3.9-3.3× 109 M ⊙ of hot gas and is at least partly coincident with a large-scale {H} {I} tidal filament, indicating that the IGM in the inner part of the group is highly multi-phase. We present evidence that the group is not yet virialized, and show that gas has probably been transported from the starburst winds of NGC 838 and NGC 839 into the surrounding IGM. Considering the possible origin of the IGM, we argue that material ejected by galactic winds may have played a significant role, contributing 20%-40% of the observed hot gas in the system.

  1. CHANDRA observations of the NGC 1550 galaxy group: Implication for the temperature and entropy profiles of 1 keV galaxy groups

    DEFF Research Database (Denmark)

    Sun, M.; Forman, W.; Vikhlinin, A.

    2003-01-01

    of three 1 keV groups ( including NGC 1550) and three 2 - 3 keV groups. The scaled entropy profiles of 1 keV groups show much larger scatter than those of hotter systems, which implies varied preheating levels. We also discuss the mass content of the NGC 1550 group and the abundance pro. le of heavy......We present a detailed Chandra study of the galaxy group NGC 1550. For its temperature (1.37 +/- 0.01 keV) and velocity dispersion (similar to300 km s(-1)), the NGC 1550 group is one of the most luminous known galaxy groups (L-bol = 1.65 x 10(43) ergs s(-1) within 200 kpc, or 0.2r(vir)). We find...... is remarkably similar to those of two other 1 keV groups with accurate temperature determination. The temperature begins to decline at 0.07r(vir) - 0.1r(vir), while in hot clusters the decline begins at or beyond 0.2rvir. Thus, there are at least some 1 keV groups that have temperature profiles significantly...

  2. Erratum: "Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium, the Chandra Grating Spectra of XTE J1817-330" (2013, Apj, 768, 60)

    Science.gov (United States)

    Gatuzz, E.; Garcia, J.; Mendoza, C.; Kallman, Timothy R.; Witthoeft, Michael C.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    In the published version of this paper, there are some minor inaccuracies in the absorption-line wavelengths listed in Table 4 as a result of a faulty reduction procedure of the Obs6615 spectrum. The shifts have been detected in a comparison with the wavelengths listed for this spectrum in the Chandra Transmission Grating Catalog and Archive (TGCat8). They are due to incorrect centroid positions of the zero-order image in both reductions as determined by the tgdetect utility which, when disentangled, yield the improved line positions of the amended Table 4 given below. It must also be pointed out that other quantitative findings of the original paper: 1. Table 5, p. 9: the column density (NH), ionization parameter, oxygen abundance of the warmabs model and the normalization and photon index of the power-law model; 2. Table 6, p. 9: the hydrogen column density of the warmabs fit; 3. Table 7, p. 9: the present oxygen equivalent widths of XTE J1817-330; and 4. Table 8, p. 10: the present oxygen column densities of XTE J1817-330 derived from both the curve of growth and warmabs model fit have been revised in the new light and are, within the estimated uncertainty ranges, in good accord with the new rendering.

  3. Inferring Compton-thick AGN candidates at z > 2 with Chandra using the >8 keV rest-frame spectral curvature

    Science.gov (United States)

    Baronchelli, L.; Koss, M.; Schawinski, K.; Cardamone, C.; Civano, F.; Comastri, A.; Elvis, M.; Lanzuisi, G.; Marchesi, S.; Ricci, C.; Salvato, M.; Trakhtenbrot, B.; Treister, E.

    2017-10-01

    To fully understand cosmic black hole growth, we need to constrain the population of heavily obscured active galactic nuclei (AGNs) at the peak of cosmic black hole growth (z ˜1-3). Sources with obscuring column densities higher than 1024 atoms cm-2, called Compton-thick (CT) AGNs, can be identified by excess X-ray emission at ˜20-30 keV, called the 'Compton hump'. We apply the recently developed Spectral Curvature (SC) method to high-redshift AGNs (2 method parametrizes the characteristic 'Compton hump' feature cosmologically redshifted into the X-ray band at observed energies method, and bright sources fit using their full spectrum with X-ray spectroscopy. In the Chandra Deep Field-South, we measure a CT fraction of 17^{+19}_{-11} per cent (3/17) for sources with observed luminosity >5 × 1043erg s-1. In the Cosmological Evolution Survey (COSMOS), we find an observed CT fraction of 15^{+4}_{-3} per cent (40/272) or 32 ± 11 per cent when corrected for the survey sensitivity. When comparing to low redshift AGNs with similar X-ray luminosities, our results imply that the CT AGN fraction is consistent with having no redshift evolution. Finally, we provide SC equations that can be used to find high-redshift CT AGNs (z > 1) for current (XMM-Newton) and future (eROSITA and ATHENA) X-ray missions.

  4. Chandra and optical/IR observations of CXO J1415.2+3610, a massive, newly discovered galaxy cluster at z ~ 1.5

    Science.gov (United States)

    Tozzi, P.; Santos, J. S.; Nonino, M.; Rosati, P.; Borgani, S.; Sartoris, B.; Altieri, B.; Sanchez-Portal, M.

    2013-03-01

    Aims: We report the discovery of CXO J1415.2+3610, a distant (z ~ 1.5) galaxy cluster serendipitously detected as an extended source with a very high significance level (S/N ~ 11) in a deep, high-resolution Chandra observation targeted to study the cluster WARP J1415.1+3612 at z = 1.03. This is the highest-z cluster discovered with Chandra so far. Moreover, the total exposure time of 280 ks with ACIS-S provides the deepest X-ray observation currently achieved on a cluster at z ≥ 1.5. Methods: We perform an X-ray spectral fit of the extended emission of the intracluster medium (ICM) with Xspec assuming a single-temperature thermal mekal model. We use optical and infrared (IR) observations from Subaru-Suprime (BVRiz), Moircs (JKs), and Spitzer-IRAC (3.6 μm) to confirm the presence of an overdensity of red galaxies matching the X-ray extended emission. We use optical and IR data to investigate the color-magnitude relation of the candidate member galaxies. Results: From a preliminary X-ray spectral analysis, we detect at a 99.5% confidence level the rest frame 6.7-6.9 keV Iron Kα line complex, from which we obtain zX = 1.46 ± 0.025. Our X-ray redshift measurement is supported by the optical and IR data. The analysis of the z - 3.6 μm color-magnitude diagram shows a well-defined sequence of red galaxies within 1' from the cluster X-ray emission peak with a color range [5 < z - 3.6 μm < 6]. The photometric redshift obtained by spectral energy distribution fitting is zphot = 1.52 ± 0.06. After fixing the redshift to z = 1.46, we perform the final spectral analysis and measure the average gas temperature with a 20% error, kT = 5.8-1.0+1.2 keV, and the Fe abundance ZFe = 1.3-0.5+0.8 Z⊙. We fit the background-subtracted surface brightness with a single beta-model out to 35 arcsec (the maximum radius where the X-ray emission is detected), and derive the deprojected electron density profile. The ICM mass is 1.09-0.2+0.3 × 1013 M⊙ within 300 kpc. Under the

  5. THE TAIWAN ECDFS NEAR-INFRARED SURVEY: ULTRA-DEEP J AND K{sub S} IMAGING IN THE EXTENDED CHANDRA DEEP FIELD-SOUTH

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Bau-Ching; Wang, Wei-Hao; Hsieh, Chih-Chiang; Lin, Lihwai; Lim, Jeremy; Ho, Paul T. P. [Institute of Astrophysics and Astronomy, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Yan Haojing [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)

    2012-12-15

    We present ultra-deep J and K{sub S} imaging observations covering a 30' Multiplication-Sign 30' area of the Extended Chandra Deep Field-South (ECDFS) carried out by our Taiwan ECDFS Near-Infrared Survey (TENIS). The median 5{sigma} limiting magnitudes for all detected objects in the ECDFS reach 24.5 and 23.9 mag (AB) for J and K{sub S} , respectively. In the inner 400 arcmin{sup 2} region where the sensitivity is more uniform, objects as faint as 25.6 and 25.0 mag are detected at 5{sigma}. Thus, this is by far the deepest J and K{sub S} data sets available for the ECDFS. To combine TENIS with the Spitzer IRAC data for obtaining better spectral energy distributions of high-redshift objects, we developed a novel deconvolution technique (IRACLEAN) to accurately estimate the IRAC fluxes. IRACLEAN can minimize the effect of blending in the IRAC images caused by the large point-spread functions and reduce the confusion noise. We applied IRACLEAN to the images from the Spitzer IRAC/MUSYC Public Legacy in the ECDFS survey (SIMPLE) and generated a J+K{sub S} -selected multi-wavelength catalog including the photometry of both the TENIS near-infrared and the SIMPLE IRAC data. We publicly release the data products derived from this work, including the J and K{sub S} images and the J+K{sub S} -selected multi-wavelength catalog.

  6. X-Ray Spectral Analyses of AGNs from the 7Ms Chandra Deep Field-South Survey: The Distribution, Variability, and Evolutions of AGN Obscuration

    Science.gov (United States)

    Liu, Teng; Tozzi, Paolo; Wang, Jun-Xian; Brandt, William N.; Vignali, Cristian; Xue, Yongquan; Schneider, Donald P.; Comastri, Andrea; Yang, Guang; Bauer, Franz E.; Paolillo, Maurizio; Luo, Bin; Gilli, Roberto; Wang, Q. Daniel; Giavalisco, Mauro; Ji, Zhiyuan; Alexander, David M.; Mainieri, Vincenzo; Shemmer, Ohad; Koekemoer, Anton; Risaliti, Guido

    2017-09-01

    We present a detailed spectral analysis of the brightest active galactic nuclei (AGNs) identified in the 7Ms Chandra Deep Field-South (CDF-S) survey over a time span of 16 years. Using a model of an intrinsically absorbed power-law plus reflection, with possible soft excess and narrow Fe Kα line, we perform a systematic X-ray spectral analysis, both on the total 7Ms exposure and in four different periods with lengths of 2-21 months. With this approach, we not only present the power-law slopes, column densities {N}{{H}}, observed fluxes, and absorption-corrected 2-10 keV luminosities L X for our sample of AGNs, but also identify significant spectral variabilities among them on timescales of years. We find that the {N}{{H}} variabilities can be ascribed to two different types of mechanisms, either flux-driven or flux-independent. We also find that the correlation between the narrow Fe line EW and {N}{{H}} can be well explained by the continuum suppression with increasing {N}{{H}}. Accounting for the sample incompleteness and bias, we measure the intrinsic distribution of {N}{{H}} for the CDF-S AGN population and present reselected subsamples that are complete with respect to {N}{{H}}. The {N}{{H}}-complete subsamples enable us to decouple the dependences of {N}{{H}} on L X and on redshift. Combining our data with those from C-COSMOS, we confirm the anticorrelation between the average {N}{{H}} and L X of AGN, and find a significant increase of the AGN-obscured fraction with redshift at any luminosity. The obscured fraction can be described as {f}{obscured}≈ 0.42 {(1+z)}0.60.

  7. An alma survey of sub-millimeter galaxies in the extended Chandra deep field south: Sub-millimeter properties of color-selected galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Decarli, R.; Walter, F.; Hodge, J. A.; Rix, H.-W.; Schinnerer, E. [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Smail, I.; Swinbank, A. M.; Karim, A.; Simpson, J. M. [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Chapman, S. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Coppin, K. E. K. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Cox, P. [IRAM, 300 rue de la piscine, F-38406 Saint-Martin d' Hères (France); Dannerbauer, H. [Universität Wien, Institut für Astrophysik, Türenschanzstrasse 17, A-1180 Wien (Austria); Greve, T. R. [University College London, Department of Physics and Astronomy, Gower Street, London WC1E 6BT (United Kingdom); Ivison, R. [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Knudsen, K. K.; Lindroos, L. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala SE-439 92 (Sweden); Van der Werf, P. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Weiß, A., E-mail: decarli@mpia.de [Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2014-01-10

    We study the sub-millimeter properties of color-selected galaxies via a stacking analysis applied for the first time to interferometric data at sub-millimeter wavelengths. We base our study on 344 GHz ALMA continuum observations of ∼20''-wide fields centered on 86 sub-millimeter sources detected in the LABOCA Extended Chandra Deep Field South (ECDFS) Sub-millimeter Survey. We select various classes of galaxies (K-selected, star-forming sBzK galaxies, extremely red objects, and distant red galaxies) according to their optical/near-infrared fluxes. We find clear, >10σ detections in the stacked images of all these galaxy classes. We include in our stacking analysis Herschel/SPIRE data to constrain the dust spectral energy distribution of these galaxies. We find that their dust emission is well described by a modified blackbody with T {sub dust} ≈ 30 K and β = 1.6 and infrared luminosities of (5-11) × 10{sup 11} L {sub ☉} or implied star formation rates of 75-140 M {sub ☉} yr{sup –1}. We compare our results with those of previous studies based on single-dish observations at 870 μm and find that our flux densities are a factor 2-3 higher than previous estimates. The discrepancy is observed also after removing sources individually detected in ALESS maps. We report a similar discrepancy by repeating our analysis on 1.4 GHz observations of the whole ECDFS. Hence, we find tentative evidence that galaxies that are associated in projected and redshift space with sub-mm bright sources are brighter than the average population. Finally, we put our findings in the context of the cosmic star formation rate density as a function of redshift.

  8. An ALMA survey of submillimeter galaxies in the extended Chandra deep field south: The redshift distribution and evolution of submillimeter galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, J. M.; Swinbank, A. M.; Smail, Ian; Alexander, D. M.; Danielson, A. L. R.; Thomson, A. P. [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Bertoldi, F.; Karim, A. [Argelander-Institute for Astronomy, Bonn University, Auf dem Hügel 71, D-53121 Bonn (Germany); De Breuck, C. [European Southern Observatory, Karl-Schwarzschild Straße, D-85748 Garching bei München (Germany); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5 (Canada); Coppin, K. E. K. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Da Cunha, E.; Hodge, J. A.; Schinnerer, E. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Dannerbauer, H. [Universität Wien, Institut für Astrophysik, Türkenschanzstraße 17, A-1180 Wien (Austria); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Ivison, R. J. [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Knudsen, K. K. [Department of Earth and Space Science, Onsala Space Observatory, Chalmers University of Technology, SE-43992 Onsala (Sweden); Poggianti, B. M., E-mail: j.m.simpson@dur.ac.uk [INAF-Astronomical Observatory of Padova, I-35122 Padova (Italy); and others

    2014-06-20

    We present the first photometric redshift distribution for a large sample of 870 μm submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z {sub phot} = 2.3 ± 0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distribution comparable to that of a complete sample of z ∼ 1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z {sub phot} = 2.5 ± 0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z ≥ 3 is at most 35% ± 5% of the total population. We derive a median stellar mass of M {sub *} = (8 ± 1) × 10{sup 10} M {sub ☉}, although there are systematic uncertainties of up to 5 × for individual sources. Assuming that the star formation activity in SMGs has a timescale of ∼100 Myr, we show that their descendants at z ∼ 0 would have a space density and M{sub H} distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.

  9. High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

    Science.gov (United States)

    Vito, F.; Brandt, W. N.; Yang, G.; Gilli, R.; Luo, B.; Vignali, C.; Xue, Y. Q.; Comastri, A.; Koekemoer, A. M.; Lehmer, B. D.; Liu, T.; Paolillo, M.; Ranalli, P.; Schneider, D. P.; Shemmer, O.; Volonteri, M.; Wang, J.

    2018-01-01

    We investigate the population of high-redshift (3 ≤ z Deep Field-South and 2 Ms Chandra Deep Field-North. Their outstanding sensitivity and spectral characterization of faint sources allow us to focus on the sub-L* regime (logLX ≲ 44), poorly sampled by previous works using shallower data, and the obscured population. Taking fully into account the individual photometric-redshift probability distribution functions, the final sample consists of ≈102 X-ray-selected AGN at 3 ≤ z 23 is ∼0.6-0.8, once incompleteness effects are taken into account, with no strong dependence on redshift or luminosity. We derived the high-redshift AGN number counts down to F0.5-2 keV = 7 × 10-18 erg cm-2 s-1, extending previous results to fainter fluxes, especially at z > 4. We put the tightest constraints to date on the low-luminosity end of AGN luminosity function at high redshift. The space density, in particular, declines at z > 3 at all luminosities, with only a marginally steeper slope for low-luminosity AGN. By comparing the evolution of the AGN and galaxy densities, we suggest that such a decline at high luminosities is mainly driven by the underlying galaxy population, while at low luminosities there are hints of an intrinsic evolution of the parameters driving nuclear activity. Also, the black hole accretion rate density and star formation rate density, which are usually found to evolve similarly at z ≲ 3, appear to diverge at higher redshifts.

  10. The Evolution of Normal Galaxy X-Ray Emission Through Cosmic History: Constraints from the 6 MS Chandra Deep Field-South

    Science.gov (United States)

    Lehmer, B. D.; Basu-Zych, A. R.; Mineo, S.; Brandt, W. N.; Eurfrasio, R. T.; Fragos, T.; Hornschemeier, A. E.; Lou, B.; Xue, Y. Q.; Bauer, F. E.; hide

    2016-01-01

    We present measurements of the evolution of normal-galaxy X-ray emission from z (is) approx. 0-7 using local galaxies and galaxy samples in the approx. 6 Ms Chandra Deep Field-South (CDF-S) survey. The majority of the CDF-S galaxies are observed at rest-frame energies above 2 keV, where the emission is expected to be dominated by X-ray binary (XRB) populations; however, hot gas is expected to provide small contributions to the observed-frame (is) less than 1 keV emission at z (is) less than 1. We show that a single scaling relation between X-ray luminosity (L(sub x)) and star-formation rate (SFR) literature, is insufficient for characterizing the average X-ray emission at all redshifts. We establish that scaling relations involving not only SFR, but also stellar mass and redshift, provide significantly improved characterizations of the average X-ray emission from normal galaxy populations at z (is) approx. 0-7. We further provide the first empirical constraints on the redshift evolution of X-ray emission from both low-mass XRB (LMXB) and high-mass XRB (HMXB) populations and their scalings with stellar mass and SFR, respectively. We find L2 -10 keV(LMXB)/stellar mass alpha (1+z)(sub 2-3) and L2 -10 keV(HMXB)/SFR alpha (1+z), and show that these relations are consistent with XRB population-synthesis model predictions, which attribute the increase in LMXB and HMXB scaling relations with redshift as being due to declining host galaxy stellar ages and metallicities, respectively. We discuss how emission from XRBs could provide an important source of heating to the intergalactic medium in the early universe, exceeding that of active galactic nuclei.

  11. Tracing the accretion history of supermassive black holes through X-ray variability: results from the ChandraDeep Field-South

    Science.gov (United States)

    Paolillo, M.; Papadakis, I.; Brandt, W. N.; Luo, B.; Xue, Y. Q.; Tozzi, P.; Shemmer, O.; Allevato, V.; Bauer, F. E.; Comastri, A.; Gilli, R.; Koekemoer, A. M.; Liu, T.; Vignali, C.; Vito, F.; Yang, G.; Wang, J. X.; Zheng, X. C.

    2017-11-01

    We study the X-ray variability properties of distant active galactic nuclei (AGNs) in the ChandraDeep Field-South region over 17 yr, up to z ˜ 4, and compare them with those predicted by models based on local samples. We use the results of Monte Carlo simulations to account for the biases introduced by the discontinuous sampling and the low-count regime. We confirm that variability is a ubiquitous property of AGNs, with no clear dependence on the density of the environment. The variability properties of high-z AGNs, over different temporal time-scales, are most consistent with a power spectral density (PSD) described by a broken (or bending) power law, similar to nearby AGNs. We confirm the presence of an anticorrelation between luminosity and variability, resulting from the dependence of variability on black hole (BH) mass and accretion rate. We explore different models, finding that our acceptable solutions predict that BH mass influences the value of the PSD break frequency, while the Eddington ratio λEdd affects the PSD break frequency and, possibly, the PSD amplitude as well. We derive the evolution of the average λEdd as a function of redshift, finding results in agreement with measurements based on different estimators. The large statistical uncertainties make our results consistent with a constant Eddington ratio, although one of our models suggest a possible increase of λEdd with lookback time up to z ˜ 2-3. We conclude that variability is a viable mean to trace the accretion history of supermassive BHs, whose usefulness will increase with future, wide-field/large effective area X-ray missions.

  12. Merger-driven Fueling of Active Galactic Nuclei: Six Dual and Offset AGNs Discovered with Chandra and Hubble Space Telescope Observations

    Science.gov (United States)

    Comerford, Julia M.; Pooley, David; Barrows, R. Scott; Greene, Jenny E.; Zakamska, Nadia L.; Madejski, Greg M.; Cooper, Michael C.

    2015-06-01

    Dual active galactic nuclei (AGNs) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers, where both or one of the black holes are AGNs, respectively. These dual and offset AGNs are valuable probes of the link between mergers and AGNs but are challenging to identify. Here we present Chandra/ACIS observations of 12 optically selected dual AGN candidates at z\\lt 0.34, where we use the X-rays to identify AGNs. We also present Hubble Space Telescope/Wide Field Camera 3 observations of 10 of these candidates, which reveal any stellar bulges accompanying the AGNs. We discover a dual AGN system with separation Δ x=2.2 kpc, where the two stellar bulges have coincident [O iii] λ5007 and X-ray sources. This system is an extremely minor merger (460:1) that may include a dwarf galaxy hosting an intermediate mass black hole. We also find six single AGNs, and five systems that are either dual or offset AGNs with separations Δ x\\lt 10 kpc. Four of the six dual AGNs and dual/offset AGNs are in ongoing major mergers, and these AGNs are 10 times more luminous, on average, than the single AGNs in our sample. This hints that major mergers may preferentially trigger higher luminosity AGNs. Further, we find that confirmed dual AGNs have hard X-ray luminosities that are half of those of single AGNs at fixed [O iii] λ5007 luminosity, on average. This could be explained by high densities of gas funneled to galaxy centers during mergers, and emphasizes the need for deeper X-ray observations of dual AGN candidates.

  13. Late-Time Evolution of Composite Supernova Remnants: Deep Chandra Observations and Hydrodynamical Modeling of a Crushed Pulsar Wind Nebula in SNR G327.1-1.1

    Science.gov (United States)

    Temim, Tea; Slane, Patrick; Kolb, Christopher; Blondin, John; Hughes, John P.; Bucciantini, Niccolo

    2015-01-01

    In an effort to better understand the evolution of composite supernova remnants (SNRs) and the eventual fate of relativistic particles injected by their pulsars, we present a multifaceted investigation of the interaction between a pulsar wind nebula (PWN) and its host SNR G327.1-1.1. Our 350 ks Chandra X-ray observations of SNR G327.1-1.1 reveal a highly complex morphology; a cometary structure resembling a bow shock, prong-like features extending into large arcs in the SNR interior, and thermal emission from the SNR shell. Spectral analysis of the non-thermal emission offers clues about the origin of the PWN structures, while enhanced abundances in the PWN region provide evidence for mixing of supernova ejecta with PWN material. The overall morphology and spectral properties of the SNR suggest that the PWN has undergone an asymmetric interaction with the SNR reverse shock(RS) that can occur as a result of a density gradient in the ambient medium and or a moving pulsar that displaces the PWN from the center of the remnant. We present hydrodynamical simulations of G327.1-1.1 that show that its morphology and evolution can be described by a approx. 17,000 yr old composite SNR that expanded into a density gradient with an orientation perpendicular to the pulsar's motion. We also show that the RSPWN interaction scenario can reproduce the broadband spectrum of the PWN from radio to gamma-ray wavelengths. The analysis and modeling presented in this work have important implications for our general understanding of the structure and evolution of composite SNRs.

  14. LATE-TIME EVOLUTION OF COMPOSITE SUPERNOVA REMNANTS: DEEP CHANDRA OBSERVATIONS AND HYDRODYNAMICAL MODELING OF A CRUSHED PULSAR WIND NEBULA IN SNR G327.1-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Temim, Tea [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Slane, Patrick [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kolb, Christopher; Blondin, John [North Carolina State University, 421 Riddick Hall, Raleigh, NC 27695 (United States); Hughes, John P. [Rutgers University, 57 US Highway 1, New Brunswick, NJ 08901 (United States); Bucciantini, Niccoló [INAF Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi, 5, 50125, Firenze Italy (Italy)

    2015-07-20

    In an effort to better understand the evolution of composite supernova remnants (SNRs) and the eventual fate of relativistic particles injected by their pulsars, we present a multifaceted investigation of the interaction between a pulsar wind nebula (PWN) and its host SNR G327.1-1.1. Our 350 Chandra X-ray observations of SNR G327.1-1.1 reveal a highly complex morphology: a cometary structure resembling a bow shock, prong-like features extending into large arcs in the SNR interior, and thermal emission from the SNR shell. Spectral analysis of the non-thermal emission offers clues about the origin of the PWN structures, while enhanced abundances in the PWN region provide evidence for a mixing of supernova ejecta with PWN material. The overall morphology and spectral properties of the SNR suggest that the PWN has undergone an asymmetric interaction with the SNR reverse shock (RS), whichcan occur as a result of a density gradient in the ambient medium and/or a moving pulsar that displaces the PWN from the center of the remnant. We present hydrodynamical simulations of G327.1-1.1 that show that its morphology and evolution can be described by a ∼17,000-year-old composite SNR that expanded into a density gradient with an orientation perpendicular to the pulsar’s motion. We also show that the RS/PWN interaction scenario can reproduce the broadband spectrum of the PWN from radio to γ-ray wavelengths. The analysis and modeling presented in this work have important implications for our general understanding of the structure and evolution of composite SNRs.

  15. THE SECOND ULTRALUMINOUS X-RAY SOURCE TRANSIENT IN M31: CHANDRA, HUBBLE SPACE TELESCOPE, AND XMM OBSERVATIONS, AND EVIDENCE FOR AN EXTENDED CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, R.; Garcia, M.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2013-08-01

    XMMU J004243.6+412519 is a transient X-ray source in M31, first discovered 2012 January 15. Different approaches to fitting the brightest follow-up observation gave luminosities 1.3-2.5 Multiplication-Sign 10{sup 39} erg s{sup -1}, making it the second ultraluminous X-ray source (ULX) in M31, with a probable black hole accretor. These different models represent different scenarios for the corona: optically thick and compact, or optically thin and extended. We obtained Chandra ACIS and Hubble Space Telescope Advanced Camera for Surveys observations of this object as part of our transient monitoring program, and also observed it serendipitously in a 120 ks XMM-Newton observation. We identify an optical counterpart at J2000 position 00:42:43.70 +41:25:18.54; its F435W ({approx}B band) magnitude was 25.97 {+-} 0.03 in the 2012 March 7 observation, and >28.4 at the 4{sigma} level during the 2012 September 7 observation, indicating a low-mass donor. We created two alternative light curves, using the different corona scenarios, finding linear decay for the compact corona and exponential decay for the extended corona; linear decay implies a disk that is >5 mag brighter than we observed. We therefore favor the extended corona scenario, but caution that there is no statistical preference for this model in the X-ray spectra alone. Using two empirical relations between the X-ray to optical ratio and the orbital period, we estimate a period of {approx}9-30 hr; this period is consistent with that of the first ULX in M31 (18{sup +5}{sub -6} hr)

  16. Prafulla Chandra Rây

    Indian Academy of Sciences (India)

    became the Vice President of the University Chemical Society and continued his research work for one more year ... chemistry literature as well, he encouraged students to go by their own inclinations to inorganic, organic ... and happiness, he had said, 'I have no sense of success on any very large scale in things achieved .

  17. Shenoi, Dr Sadananda Satheesh Chandra

    Indian Academy of Sciences (India)

    Specialization: Physical Oceanography, Ocean-Atmosphere Interaction and Satellite Oceanography Address: Director, Indian National Centre for Ocean Information Services, Ocean Valley, Pragati Nagar (BO), Nizampet P.O., Hyderabad 500 090, A.P.. Contact: Office: (040) 2389 5000. Residence: (040) 6574 3155

  18. The 2-79 keV X-ray spectrum of the circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully compton-thick active galactic nucleus

    DEFF Research Database (Denmark)

    Arévalo, P.; Bauer, F. E.; Puccetti, S.

    2014-01-01

    The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical...... by an optically thick torus, where the intrinsic spectrum is a power law of photon index Γ = 2.2-2.4, the torus has an equatorial column density of NH = (6-10) × 1024 cm-2, and the intrinsic AGN 2-10 keV luminosity is (2.3-5.1) × 1042 erg s-1. These values place Circinus along the same relations as unobscured...

  19. The era of synoptic galactic archeology: using HST and Chandra observations to constrain the evolution of elliptical galaxies through the spatial distribution of globular clusters and X-ray binaries.

    Science.gov (United States)

    D'Abrusco, Raffaele; Fabbiano, Giuseppina; Zezas, Andreas

    2017-01-01

    Most of the stellar mass observed today in early-type galaxies is thought to be due to merging and accretion of smaller companions, but the details of these processes are still poorly constrained. Globular clusters, visible from the center to the halo of galaxies, reflect the evolution of their host galaxy in their kinematic, photometric and spatial distributions. By characterizing the spatial distribution of the population of globular clusters extracted from archival HST data of some of the most massive elliptical galaxies in the local Universe with a novel statistical approach, we recently discovered that two-dimensional spatial structures at small radii are common (D’Abrusco et al. 2014a; 2014b; 2015). Such structures, not detectable from ground-based data, can be linked to events in the evolution of the host galaxy. Moreover, we devised an interpretative framework that, based on the form, area and number of globular clusters of such structures, infers the frequency of major mergers and the mass spectrum of the accreted companions.For some of the galaxies investigated, X-ray data from Chandra joint observing programs were also available. Our method, applied to the distribution of X-ray binaries, has revealed, at least in the case of two galaxies (D’Abrusco et al. 2014a; D’Abrusco et al.23014c) the existence of overdensities that are not associated to globular cluster structures. These findings provide complementary hints about the evolution of the stellar component of these galaxies that can be used to further refine the sequence of events that determined their growth.In this contribution, we will summarize our main results and highlight the novelty of our approach. Furthermore, we will advocate the fundamental importance of joint observations of galaxies by HST and Chandra as a way to provide unique, complementary views of such systems and unlock the mysteries of their evolution.

  20. Chandra studies of the globular cluster 47 Tucanae: A deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window

    Science.gov (United States)

    Bhattacharya, Souradeep; Heinke, Craig O.; Chugunov, Andrey I.; Freire, Paulo C. C.; Ridolfi, Alessandro; Bogdanov, Slavko

    2017-12-01

    We combined Chandra ACIS observations of the globular cluster 47 Tucanae (hereafter, 47 Tuc) from 2000, 2002, and 2014-15 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. We have detected 370 X-ray sources within the half-mass radius (2'.79) of the cluster, 81 of which are newly identified, by including new data and using improved source detection techniques. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. (2001). We present alternative positions derived from two methods, centroiding and image reconstruction, for faint, crowded sources. We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are well fit by black body or neutron star atmosphere models, with temperatures, luminosities and emitting radii similar to those of other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities. We limit X-ray emission from the full surface of the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as α<2.5×10^{-9}$ and constrain the shape of the r-mode instability window.

  1. Harish-Chandra Research Institute, Allahabad

    Indian Academy of Sciences (India)

    etry is a study of a space M made up of points with varM>us sorts of structures, analysis involves functions and its derivatives, and ... In physics, the general aim is to understand the material world - what everything around us is made of and what .... Scientists in HRI mainly work on inflation, numerical simulations on formation ...

  2. Chemical Research of Sir Prafulla Chandra Ray

    Indian Academy of Sciences (India)

    Author Affiliations. Sreebrata Goswami1 Samaresh Bhattacharya2. Department of Inorganic Chemistry Indian Association for the Cultivation of Science Calcutta 700032, India. Department of Chemistry Inorganic Chemistry Section Jadavpur University Calcutta 700032, India.

  3. Chandra Observations of Tycho's Supernova Remnant

    Indian Academy of Sciences (India)

    Author Affiliations. U. Hwang1 R. Petre2 A. E. Szymkowiak3 S. S. Holt4. NASA GSFC (University of Maryland), USA; University of Maryland, USA; Yale University, USA; Olin College of Engineering, USA ...

  4. Dwarf Galaxies in the Chandra COSMOS Legacy Survey

    Science.gov (United States)

    Civano, Francesca Maria; Mezcua, Mar; Fabbiano, Giuseppina; Marchesi, Stefano; Suh, Hyewon; Volonteri, Marta; cyrille

    2018-01-01

    The existence of intermediate mass black holes (100 7. While detecting these seed black holes in the young Universe is observationally challenging, the nuclei of local dwarf galaxies are among the best places where to look for them as these galaxies resemble in mass and metallicity the first galaxies and they have not significantly grown through merger and accretion processes. We present a sample of 40 AGN in dwarf galaxies (107 Legacy survey. Once the star formation contribution to the X-ray emission is subtracted, the AGN luminosities of the 40 dwarf galaxies are in the range L(0.5-10 keV)~1039 - 1044 erg/s. With 12 sources at z > 0.5, our sample constitutes the highest-redshift discovery of AGN in dwarf galaxies. One of the dwarf galaxies is the least massive galaxy (M* = 6.6x107 Msun) found so far to host an active BH. We also present for the first time the evolution of the AGN fraction with stellar mass, X-ray luminosity, and redshift in dwarf galaxies out to z = 0.7, finding that it decreases with X-ray luminosity and stellar mass. Unlike massive galaxies, the AGN fraction is found to decrease with redshift, suggesting that AGN in dwarf galaxies evolve differently than those in high-mass galaxies.

  5. 2017-2018 Travel Expense Reports for Chandra Madramootoo, Vice ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Chantal Taylor

    07-11. Destination(s):. Kenya, Uganda and Tanzania. Airfare: $4,788.97. Other. Transportation: $147.43. Accommodation: $2,058.50. Meals and. Incidentals: $701.92. Other: $399.15. Total: $8,095.97. Comments: From residence in Montreal, ...

  6. 2016-2017 Expense report for Chandra Madramootoo | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2017-03-20

    $10,750.19. Board meetings. March 20, 2017 to March 22, 2017. CA$821.31. Board meetings. November 20, 2016 to November 23, 2016. CA$907.94. Orientation on research impact for new Governors. August 14, 2016 to August 23, 2016.

  7. Acharya Prafulla Chandra at the College of Science

    Indian Academy of Sciences (India)

    bite. Museum. Out of his gifts to the University, several rooms were added to the southwest wing of the Chemistry Department for housing laboratories, a library and the Indian Chemical Society. One of the rooms, divided into three compartments by partition to serve as the kitchen, storeroom and bedroom, was gifted back to.

  8. Materials Research Society Symposium on the Electrical, Optical and Magnetic Properties of Organic Solid State Materials Held in Boston Massachusetts on 27 November-2 December 1989

    Science.gov (United States)

    1989-12-01

    M.E. Gingerich, S.J. Hickey*, M.A. Putnam **, C.M. Shaw***, Naval Research Laboratory. Washi gton Fused silica which were formed in the hydrogen- DCM...CORONA POLED POLYMER FILMS, Neil Williams, Vijay K. Varadan, and Hilary L. Hampsch, Northwestern University, Vasundara V. Varadan, Pennsylvania State...GOODWIN, MICHAEL W., E7.9 GUARNIERI, C. RICHARD, AI.8, HAMPSCH, HILARY L., Q13.6 HAYASHI, NOBUYUKI, A2.4 GOORSKY, M., B2.7, G12.3 F5.4 HAN, C.C., J6.2

  9. Rapport de frais de 2016-2017 pour Chandra Madramootoo | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Total des frais de déplacement : CAD$10,750.19. Réunion du Conseil des gouverneurs. 20 mars 2017 au 22 mars 2017. CAD$821.31. Réunion du Conseil des gouverneurs. 20 novembre 2016 au 23 novembre 2016. CAD$907.94. Initiation des nouveaux gouverneurs aux impacts de la recherche. 14 août 2016 au 23 août ...

  10. Chandra observations of an exceptional cluster of galaxies at z=1.7

    Science.gov (United States)

    Hlavacek-Larrondo, Julie

    2017-09-01

    We propose to obtain the first X-ray image of an exceptional cluster of galaxies, which stands out as being an extremely distant (z=1.7) and massive (2-5*10^14M_sun) cluster, harbouring a still-assembling BCG that is forming stars at a prodigious rate of 860M_sun/yr. Combined with our recently awarded VLA and HST data, the goal of this proposal is to: 1) determine the dynamical state of the cluster; 2) provide an independant estimate of the cluster mass; and 3) study the X-ray properties of the extreme central AGN. The observations will significantly help in our understanding of the formation and evolution of massive clusters and BCGs, as well as the role of AGN in astrophysical feedback. In summary, in 170 ks, this proposal will advance several aspects of high-z physics.

  11. 110 1*Atkuru Veera Venkata Naga Krishna Sunil Kumar, 2Chandra ...

    African Journals Online (AJOL)

    11. Manisha G, Usha P, Vandana P. Development and validation of RP-HPLC method for estimation of vardenafil in bulk and pharmaceutical formulation. Am. J PharmTech. Res. 2013;3:928-938. 12. Subba Rao DV, Surendranath KV,. Radhakrishnan P, Suryanarayana MV,. Raghuram P. A stability indicating. LC method for.

  12. Page 1 434 Shikha Mishra, Sanjay Tiwari and B P Chandra ...

    Indian Academy of Sciences (India)

    Voc which can be obtained. The flat band potential is determined from the photo- current onset (figure 2). Taking Ef, redox for the sulphide/polysulphide couple as. -071 W, the band bending comes out to be 068 and 0.49W for annealed and unannealed film respectively. It is clear from the above values of band bending for.

  13. Chandra Data Analysis of H2O Megamaser Galaxy NGC 4258

    Indian Academy of Sciences (India)

    Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately.

  14. Symbiotic Stars in X-rays. II. Faint Sources Detected with XMM-Newton and Chandra

    Science.gov (United States)

    Nunez, N. E.; Luna, G. J. M.; Pillitteri, I.; Mukai, K.

    2014-01-01

    We report the detection from four symbiotic stars that were not known to be X-ray sources. These four object show a ß-type X-ray spectrum, that is, their spectra can be modeled with an absorbed optically thin thermal emission with temperatures of a few million degrees. Photometric series obtained with the Optical Monitor on board XMM-Newton from V2416 Sgr and NSV 25735 support the proposed scenario where the X-ray emission is produced in a shock-heated region inside the symbiotic nebulae.

  15. VizieR Online Data Catalog: CANDELS GOODS-S sources Chandra counterparts (Cappelluti+, 2016)

    Science.gov (United States)

    Cappelluti, N.; Comastri, A.; Fontana, A.; Zamorani, G.; Amorin, R.; Castellano, M.; Merlin, E.; Santini, P.; Elbaz, D.; Schreiber, C.; Shu, X.; Wang, T.; Dunlop, J. S.; Bourne, N.; Bruce, V. A.; Buitrago, F.; Michalowski, M. J.; Derriere, S.; Ferguson, H. C.; Faber, S. M.; Vito, F.

    2016-04-01

    The 4Ms CDFS consists of 23 observations described in Table 1 of Luo et al. (2008, Cat. J/ApJS/179/19) plus other 31 pointings described in X11 for a total exposure of ~4Ms. For the purpose of this paper we employed only observations taken with a focal temperature of <=-120°C since at higher T the background cannot be modeled with our technique. (2 data files).

  16. Page 1 72 Chandra P Sharma These grafts are treated with acetone ...

    Indian Academy of Sciences (India)

    are treated with distilled ethanol for 48 hr to remove all ungrafted HEMA monomer from the samples (Jansen and Ellinghorst 1979). 3. Platelet adhesion. Washed calf platelets are prepared and suspended in tyrode solution (Sharma and Lissy. 1982) for adhesion studies. The polymers under study are exposed to platelet.

  17. Page 1 220 K. Chandra Sekharan and - dea (t)= }, (t). When K= 1, u ...

    Indian Academy of Sciences (India)

    dea (t)= }, (t). When K= 1, u = }, \\, = n, the definition reads as follows:–. A series 2 a, is said to be summable (Ji n) to the sum S, if the series f co sin nt. 2 an (**) r; : 0 Plf converges for real t > 0, and if. - sin nt 6. Lim 2 a. (*). S,. # -}. () Pl which is Lebesgue's summability. When K+ 2, u = }, \\, = n, the definition reads thus: A series 2 ...

  18. Page 1 82 SUBHASH CHANDRA AND B. K. NAYAR and proceeds ...

    Indian Academy of Sciences (India)

    containing cells (Figs. 3,. 4, n). In older stipes these cells often collapse, forming a continuous muci- lage canal. As in the rhizome, the phloem forms a thin sheath, the pericycle is 2-layered and the endodermis ill-differentiated, Dense deposits of starch.

  19. The restless universe understanding X-ray astronomy in the age of Chandra and Newton

    CERN Document Server

    Schlegel, Eric M

    2002-01-01

    This title tells the story of the development and launch of a major space-based telescope, and explains the discoveries of the nature of the universe in the X-ray spectre. The author looks at the brief history of X-ray astronomy to explore what can and has been learnt by using X-ray.

  20. Page 1 80 Chandra PSharma, Geetha Kurian and M K Sheela Table ...

    Indian Academy of Sciences (India)

    "Since the yty value for ethylene glycol is 477, which is not included in table value 48 has been used for sy andys values as a fair approximation. Table 2. Platelet adhesion and plasma recalcification time (PRr) to nylon and trypsinated nylon surfaces,. Mean PRT (sec). Surfaces platelets SD. Glass surface reer 862.

  1. Change in email domain name

    Indian Academy of Sciences (India)

    821 Quantum Computation. Particle and Wave Aspects of Algorithms. Apoorva Patel. 836 Excursions into Diverse Fields. Jagdish Mehra. 849 The Errors of Feynman and Hibbs. Daniel Styer. SERIES ARTICLES. 854 Dawn of Science. The Invisible Weight. T Padmanabhan. REFLECTIONS. 860 What is Science? Richard ...

  2. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Sanjeev Sharma. Articles written in Journal of Earth System Science. Volume 118 Issue 1 February 2009 pp 41-48. Aerosol optical depths at Mohal-Kullu in the northwestern Indian Himalayan high altitude station during ICARB · Jagdish C Kuniyal Alpana Thakur Harinder K ...

  3. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    pp 405-410 Single Crystals. Optical and electrical properties of ZrSe3 single crystals grown by chemical vapour transport technique · Kaushik Patel Jagdish Prajapati Rajiv Vaidya S G Patel · More Details Abstract Fulltext PDF. Single crystals of the lamellar compound, ZrSe3, were grown by chemical vapour transport ...

  4. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Harinder K Thakur. Articles written in Journal of Earth System Science. Volume 118 Issue 1 February 2009 pp 41-48. Aerosol optical depths at Mohal-Kullu in the northwestern Indian Himalayan high altitude station during ICARB · Jagdish C Kuniyal Alpana Thakur Harinder ...

  5. VizieR Online Data Catalog: LBDS-Lynx region GMRT 150-MHz obs. (Ishwara-Chandra+, 2010)

    Science.gov (United States)

    Ishwara-Chandra, C. H.; Sirothia, S. K.; Wadadekar, Y.; Pal, S.; Windhorst, R.

    2011-08-01

    It has been known for nearly three decades that high-redshift radio galaxies exhibit steep radio spectra, and hence ultrasteep spectrum radio sources provide candidates for high-redshift radio galaxies. Nearly all radio galaxies with z>3 have been found using this redshift-spectral index correlation. We have started a programme with the Giant Metrewave Radio Telescope (GMRT) to exploit this correlation at flux density levels about 10 to 100 times deeper than the known high-redshift radio galaxies which were identified primarily using the already available radio catalogues. In our programme, we have obtained deep, high-resolution radio observations at 150MHz with GMRT for several "deep" fields which are well studied at higher radio frequencies and in other bands of the electromagnetic spectrum, with an aim to detect candidate high-redshift radio galaxies. In this paper we present results from the deep 150-MHz observations of the LBDS-Lynx field (Leiden-Berkeley Deep Survey), which has been already imaged at 327, 610 and 1412MHz with the Westerbork Synthesis Radio Telescope and at 1400 and 4860MHz with the Very Large Array. (2 data files).

  6. An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : Source Catalog and Multiplicity

    NARCIS (Netherlands)

    Hodge, J.; Karim, A.; Smail, I.; Swinbank, A.; Walter, F.; Biggs, A.; Ivison, R.; Weiss, A.; Alexander, D.; Bertoldi, F.; Brandt, W.; Chapman, S.; Coppin, K.; Cox, P.; Danielson, A.; Dannerbauer, H.; De, Breuck C.; Decarli, R.; Edge, A.; Greve, T.; Knudsen, K.; Menten, K.; Rix, H.; Schinnerer, E.; Simpson, J.; Wardlow, J.; Werf, van der P.P.

    2013-01-01

    We present an Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 survey of 126 submillimeter sources from the LABOCA ECDFS Submillimeter Survey (LESS). Our 870 {$μ$}m survey with ALMA (ALESS) has produced maps ~{}3{ imes} deeper and with a beam area ~{}200{ imes} smaller than the original

  7. The 26th anniversary outburst of jet-driving symbiotic binary MWC 560: results from Chandra, Swift, and optical spectroscopy

    Science.gov (United States)

    Lucy, Adrian B.; Sokoloski, J. L.; Munari, U.; Kuin, N. P. M.; Darnley, M. J.; Luna, G. J. M.; Knigge, C.; Valisa, P.; Milani, A.

    2016-03-01

    The symbiotic star MWC 560 = V694 Mon, which is believed to usually drive a jet along the line of sight (e.g., Schmid et al. 2001), is undergoing a sustained outburst (ATel #8653) rivaling its previous brightest outburst of 1990 (Tomov et al. 1990, Leibowitz and Formiggini 2015).

  8. Extended X-Ray Monitoring of Gravitational Lenses with Chandra and Joint Constraints on X-Ray Emission Regions

    Science.gov (United States)

    Guerras, Eduardo; Dai, Xinyu; Steele, Shaun; Liu, Ang; Kochanek, Christopher S.; Chartas, George; Morgan, Christopher W.; Chen, Bin

    2017-02-01

    We present an X-ray photometric analysis of six gravitationally lensed quasars, with observation campaigns spanning from 5 to 14 years, measuring the total (0.83-21.8 keV restframe), soft- (0.83-3.6 keV), and hard- (3.6-21.8 keV) band image flux ratios for each epoch. Using the ratios of the model-predicted macro-magnifications as baselines, we build differential microlensing light curves and obtain joint likelihood functions for the average X-ray emission region sizes. Our analysis yields a probability distribution function for the average half-light radius of the X-ray emission region in the sample that peaks slightly above 1 gravitational radius and with nearly indistinguishable 68 % confidence (one-sided) upper limits of 17.8 and 18.9 gravitational radii for the soft and hard X-ray emitting regions, assuming a mean stellar mass of 0.3 M ⊙. We see hints of energy dependent microlensing between the soft and hard bands in two of the objects. In a separate analysis on the root-mean-square (rms) of the microlensing variability, we find significant differences between the soft and hard bands, but the sign of the difference is not consistent across the sample. This suggests the existence of some kind of spatial structure to the X-ray emission in an otherwise extremely compact source. We also discover a correlation between the rms microlensing variability and the average microlensing amplitude.

  9. Export fluxes of geochemical solutes in the meltwater stream of Sutri Dhaka Glacier, Chandra basin, Western Himalaya.

    Science.gov (United States)

    Singh, Ajit T; Laluraj, C M; Sharma, Parmanand; Patel, Lavkush K; Thamban, Meloth

    2017-10-12

    The hydrochemistry of meltwater from the Sutri Dhaka Glacier, Western Himalaya, has been studied to understand the influence of the factors controlling the weathering processes of the glaciers during the peak ablation period. The high solar irradiance prompted intense melting, which has raised the stream flow of the glacier. The meltwater has been observed as slightly alkaline (mean pH 8.2) and contains the major anions (HCO3- > SO42- > NO3- > Cl-) and cations (Ca2+ > Mg2+ > K+ > Na+ > NH4+) with Ca2+ (78.5%) and HCO3- (74.5%) as the dominant species. The piper diagram indicates the category of stream meltwater as Ca2+-HCO3- type. In addition, it is evident from the Gibbs diagram that the interaction between the meltwater and bedrock controls the ionic concentrations of the glacial meltwater. The high ratio value (~ 0.75) of HCO3-/(HCO3- + SO42-) indicates that the carbonate weathering is dominant. Fe and Al followed by Mn, Sr, and Ti are the most dominant trace elements present in the meltwater. The significant negative correlation exhibited by the major ions and Sr with the discharge is recommended for the enrichment of these solutes during the lean discharge periods. However, the insignificant correlation of Fe, Al, Mn, and Ti with discharge suggests their physicochemical control. The principal component analysis (PCA) carried has highlighted three dominant composites, i.e., the water-rock interaction, atmospheric dust inputs, and physicochemical changes in the meltwater. Hence, the present study elucidates the export of geochemical solutes from Sutri Dhaka Glacier and factors governing the water chemistry, which helps in the better understanding of hydrochemical processes of the Himalayan glaciers and substantial improvement of our understanding about the glacio-hydrological environments and their response in the scenario of global warming.

  10. Environment of 1 ≤ z ≤ 2 MIR selected obscured and unobscured AGNs in the Extended Chandra Deep Field South

    Science.gov (United States)

    Bornancini, Carlos Guillermo; Taormina, Mónica Silvia; Lambas, Diego García

    2017-08-01

    Context. In unified models, different types of active galaxy nuclei (AGN) correspond to a single class of objects, where their observed differences are solely due to the different orientations of the obscuring material around the central inner regions. Recent studies also show that this obscuring material can even extend at galactic scales due to debris from galaxy interactions and/or mergers. In standard unified models the different AGN types are expected to show similar galaxy environments. Aims: We aim to investigate properties and environment of obscured and unobscured AGNs selected from mid-infrared (MIR) bands from the Multiwavelength Survey by Yale-Chile (MUSYC), in order to test the unified model and evolutionary scenarios. Methods: The sample of AGNs was selected from images obtained with the Infrared Array Camera (IRAC) mounted on the Spitzer Space Telescope, based on their MIR colors centered at wavelengths [3.6], [4.5], [5.8] and [8.0] microns. We selected two samples of AGNs with redshifts in the range 1 ≤ z ≤ 2 and rest-frame absolute magnitudes Mv ≤ -21: obscured and unobscured AGNs by means of a simple optical-MIR color cut criterion (R- [4.5] = 3.05.) Results: We find that obscured AGNs are intrinsically optically faint in the R band, suggesting that luminous IR-selected AGNs have a significant dust extinction. From a cross-correlation with several X-ray surveys, we find that the majority of the AGNs in our sample have X-ray luminosities similar to those found in Seyfert-like galaxies. We study the properties of galaxies surrounding these two samples. Neighbouring galaxies located close to ( 200 kpc) obscured AGNs tend to have redder colors, compared to the local environment of unobscured AGNs. Results obtained from a KS test show that the two color distributions are different at 95% confidence level. We find that obscured AGNs are located in denser local galaxy environments compared to the unobscured AGN sample. Conclusions: Our results suggest that AGN obscuration can occur at galactic scales, possibly due to galaxy interactions or mergers, and that the simple unified model based solely on the local torus orientation may not be sufficient to explain all the observations.

  11. A Chandra X-ray analysis of Abell 1664: cooling, feedback, and star formation in the central cluster galaxy

    NARCIS (Netherlands)

    Kirkpatrick, C.C.; McNamara, B.R.; Rafferty, D.A.; Nulsen, P.E.J.; Bîrzan, L.; Kazemzadeh, F.; Wise, M.W.; Gitti, M.; Cavagnolo, K.W.

    2009-01-01

    The brightest cluster galaxy (BCG) in the Abell 1664 cluster is unusually blue and is forming stars at a rate of similar to 23 M-circle dot yr(-1). The BCG is located within 5 kpc of the X-ray peak, where the cooling time of 3.5 x 10(8) yr and entropy of 10.4 keV cm(2) are consistent with other

  12. A Chandra X-Ray Analysis of Abell 1664: Cooling, Feedback, and Star Formation in the Central Cluster Galaxy

    Science.gov (United States)

    Kirkpatrick, C. C.; McNamara, B. R.; Rafferty, D. A.; Nulsen, P. E. J.; Bîrzan, L.; Kazemzadeh, F.; Wise, M. W.; Gitti, M.; Cavagnolo, K. W.

    2009-05-01

    The brightest cluster galaxy (BCG) in the Abell 1664 cluster is unusually blue and is forming stars at a rate of ~ 23 M sun yr-1. The BCG is located within 5 kpc of the X-ray peak, where the cooling time of 3.5 × 108 yr and entropy of 10.4 keV cm2 are consistent with other star-forming BCGs in cooling flow clusters. The center of A1664 has an elongated, "barlike" X-ray structure whose mass is comparable to the mass of molecular hydrogen, ~1010 M sun in the BCG. We show that this gas is unlikely to have been stripped from interloping galaxies. The cooling rate in this region is roughly consistent with the star formation rate, suggesting that the hot gas is condensing onto the BCG. We use the scaling relations of Bîrzan et al. to show that the active galactic nucleus (AGN) is underpowered compared to the central X-ray cooling luminosity by roughly a factor of three. We suggest that A1664 is experiencing rapid cooling and star formation during a low state of an AGN feedback cycle that regulates the rates of cooling and star formation. Modeling the emission as a single-temperature plasma, we find that the metallicity peaks 100 kpc from the X-ray center, resulting in a central metallicity dip. However, a multi-temperature cooling flow model improves the fit to the X-ray emission and is able to recover the expected, centrally peaked metallicity profile.

  13. The HEP Game : Simulator Game of Particle Detector & HEP Laboratory Facilities PRESENTATION - Nathaniel Chandra Harjanto - Indonesia- CERN Summer Studentship 2013

    CERN Document Server

    Harjanto, Nathaniel Chandra

    2013-01-01

    Since the discovery of Higgs boson on 4 July 2012, CERN has increased its Outreach aspect to allow more people to gain knowledge about particle physics and the researches related to it especially in CERN. As part of CERN’s Outreach effort to spread the knowledge throughout the world, we work on a collaboration project between ATLAS and LHCb experiments to make a multi-platform game to educate players about particle physics and CERN also let them have fun at the same time so the education process is a lot more effective. The knowledge of Particle Physics is incomprehensible for most people such as children, teenagers, and people in general who are not being specifically a particle physicist. Therefore, there is a need to promote and spread the knowledge on particle physics throughout the world, and CERN as the world leading institution in particle physics research plays an essential role. Particle physics is not a simple matter that is easily understood by most people, thus the challenge is to make an educat...

  14. The HEP Game : Simulator Game of Particle Detector & HEP Laboratory Facilities POSTER - Nathaniel Chandra Harjanto - Indonesia- CERN Summer Studentship 2013

    CERN Document Server

    Harjanto, Nathaniel Chandra

    2013-01-01

    Since the discovery of Higgs boson on 4 July 2012, CERN has increased its Outreach aspect to allow more people to gain knowledge about particle physics and the researches related to it especially in CERN. As part of CERN’s Outreach effort to spread the knowledge throughout the world, we work on a collaboration project between ATLAS and LHCb experiments to make a multi-platform game to educate players about particle physics and CERN also let them have fun at the same time so the education process is a lot more effective. The knowledge of Particle Physics is incomprehensible for most people such as children, teenagers, and people in general who are not being specifically a particle physicist. Therefore, there is a need to promote and spread the knowledge on particle physics throughout the world, and CERN as the world leading institution in particle physics research plays an essential role. Particle physics is not a simple matter that is easily understood by most people, thus the challenge is to make an educat...

  15. The HEP Game : Simulator Game of Particle Detector & HEP Laboratory Facilities REPORT - Nathaniel Chandra Harjanto - Indonesia- CERN Summer Studentship 2013

    CERN Document Server

    Harjanto, Nathaniel Chandra

    2013-01-01

    Since the discovery of Higgs boson on 4 July 2012, CERN has increased its Outreach aspect to allow more people to gain knowledge about particle physics and the researches related to it especially in CERN. As part of CERN’s Outreach effort to spread the knowledge throughout the world, we work on a collaboration project between ATLAS and LHCb experiments to make a multi-platform game to educate players about particle physics and CERN also let them have fun at the same time so the education process is a lot more effective. The knowledge of Particle Physics is incomprehensible for most people such as children, teenagers, and people in general who are not being specifically a particle physicist. Therefore, there is a need to promote and spread the knowledge on particle physics throughout the world, and CERN as the world leading institution in particle physics research plays an essential role. Particle physics is not a simple matter that is easily understood by most people, thus the challenge is to make an educat...

  16. 'The Relation of Biology to Astronomy' and Theology: Panspermia and Panentheism; Revolutionary Convergences Advanced by Fred Hoyle and Chandra Wickramasinghe

    Science.gov (United States)

    Walker, Theodore, Jr.

    2012-06-01

    In contrast to the Copernican revolution in astro-geometry, the Hoyle-Wickramasinghe contribution to the recent and continuing revolution in astrobiology - "cometary panspermia" - features astronomy and biology converging toward theology. They employed astro-biotic reasoning (often labeled "anthropic" reasoning) to demonstrate that life is made possible by the deliberate controlling influence of the living all-embracing "intelligent universe." This is consistent with panentheism [pan-en-theos-ism, not pantheism]. As advanced by Hoyle and Wickramasinghe, cometary panspermia is panentheistic. Also, neoclassical panentheism requires generic panspermia, and favors cometary panspermia.

  17. Pursuing the Bottom Line: How the Middle East Will be Affected by an Aging America

    Science.gov (United States)

    2007-09-01

    economic and cultural imperialism. One of the most outspoken people for the benefits of globalization is Jagdish Bhagwati. In his book, titled In Defense...highlighted above prove to be true, the Middle East could be a tinder box for years to come. The three sources of potential instability are...income and benefits to the aged population that is no longer in the workforce. As the population ages, the strain put on the entitlement programs of

  18. Optimization techniques in statistics

    CERN Document Server

    Rustagi, Jagdish S

    1994-01-01

    Statistics help guide us to optimal decisions under uncertainty. A large variety of statistical problems are essentially solutions to optimization problems. The mathematical techniques of optimization are fundamentalto statistical theory and practice. In this book, Jagdish Rustagi provides full-spectrum coverage of these methods, ranging from classical optimization and Lagrange multipliers, to numerical techniques using gradients or direct search, to linear, nonlinear, and dynamic programming using the Kuhn-Tucker conditions or the Pontryagin maximal principle. Variational methods and optimiza

  19. Spatially resolving a starburst galaxy at hard X-ray energies: NuSTAR, CHANDRA, AND VLBA observations of NGC 253

    DEFF Research Database (Denmark)

    Wik, D. R.; Lehmer, B. D.; Hornschemeier, A. E.

    2014-01-01

    Prior to the launch of NuSTAR, it was not feasible to spatially resolve the hard (E > 10 keV) emission from galaxies beyond the Local Group. The combined NuSTAR data set, comprised of three ~165 ks observations, allows spatial characterization of the hard X-ray emission in the galaxy NGC 253 for ...

  20. f(cm) =

    Indian Academy of Sciences (India)

    [5] S Chandra, W H Kegel, R J Le Roy and T Hertenstein, Astron. Astrophys. Suppl. 114, 175 (1995). [6] S Chandra, U V Maheshwari and A K Sharma, Indian J. Pure Appl. Phys. 34, 925 (1996). [7] S Chandra, U V Maheshwari and A K Sharma, Astron. Astrophys. Suppl. 117, 557 (1996). Pramana – J. Phys., Vol. 56, No.

  1. Einstein -coefficients for rotational transitions in the ring-chain ...

    Indian Academy of Sciences (India)

    1994). [5] S Chandra and Rashmi, Astron. Astrophys. Suppl. 131, 137 (1998). [6] S Chandra, D A Varshalovich and W H Kegel, Pramana - J. Phys. 25, 557 (1995). [7] S Chandra, Indian J. Phys. 76В, 649 (2002). Pramana - J. Phys., Vol. 62, No.

  2. Mapping of cosmic web filaments around A133

    Science.gov (United States)

    Kraft, Ralph

    2017-09-01

    We propose to use Chandra to map the large scale structure along the potential Cosmic Web filaments converging on Abell 133 found in the previous Chandra programs. The initial goal is to extend Chandra exposure along the brightest of the three filaments by approximately 1 Mpc.

  3. Simultaneous bilateral posterior fracture dislocation of the shoulders in a young man with unexpected severe vitamin D deficiency

    Directory of Open Access Journals (Sweden)

    O'Neill D

    2012-05-01

    Full Text Available Deborah O’Neill1, Jagdish R Nair1, Khalid A Binymin1,21Rheumatology Unit, Southport General Hospital, Southport, 2Rheumatology Department, Liverpool University, Liverpool, Merseyside, UKAbstract: Simultaneous bilateral posterior fracture dislocation of the shoulders is a rare clinical presentation. There are three main etiologies described in the literature. Given that it presents with relatively uncharacteristic symptoms, in many cases it is diagnosed late. We present the case of a man who was admitted with bilateral posterior fracture dislocation of the shoulders following a seizure. Investigations revealed severe vitamin D deficiency as the principal contributory factor to his injury. This is an important association because failure to recognize and treat this can result in significant morbidity in susceptible groups.Keywords: bilateral fracture, dislocation, shoulder, vitamin D deficiency

  4. EDITORIAL: Greetings from the new Editor-in-Chief

    Science.gov (United States)

    Garcia, Ephrahim

    2008-02-01

    I am Professor Ephrahim Garcia, an Associate Professor at Sibley School of Mechanical and Aerospace Engineering at Cornell University in Ithaca, New York. I have been at Cornell University since 2002, spent four years as a Program Manager at the Defense Advanced Research Project Agency from 1998-2002, and before that seven years at the Department of Mechanical Engineering at Vanderbilt University in Nashville, Tennessee. I have served on the Editorial Advisory Board of Smart Materials and Structures (SMS) for the last six years. It is a humbling thing to be asked to take up the post of Editor-in-Chief in a field with so many talented researchers. I would like to say a heartfelt thanks to the members of the Editorial Board and IOP Publishing for their confidence in me. Most importantly, I would like to thank Professor Vijay Varadan of the University of Arkansas and Professor Richard Claus of Virginia Polytechnic Institute and State University for their efforts in launching the journal 16 years ago. They have been stewards, promoters and, especially Vijay, key to the operation and function of SMS for all these years, and our research community is indebted to them. Professors Varadan and Claus have dedicated their careers to the area of smart materials and structures and we are very grateful for their leadership, mentoring and contribution. SMS is a thriving journal offering papers on all technical areas concerned with smart materials, systems and structures from the micro- and nanoscale to the macroscale. The journal is undergoing some major changes, including the recent transferal of papers to IOP Publishing's peer-review management system. With this new system authors can expect fast publication times of around 4 or 5 months from submission, and excellent author service. In this world of ever changing technology, the Editorial Board and I aim to reduce the time to publication for researchers in this exciting area of science and engineering. I am in the process of

  5. Ionic drift velocity measurement on hot-pressed Ag ion conducting ...

    Indian Academy of Sciences (India)

    Author Affiliations. Angesh Chandra1. Solid State Physics Research Laboratory, Department of Applied Physics, Shri Shankaracharya Institute of Professional Management & Technology, Raipur 492 015, India ...

  6. to view fulltext PDF

    Indian Academy of Sciences (India)

    Agarwal Neelima, Univ. of Allahabad and Harish-Chandra Research Institute, Alla- habad 211 019, India neel1dph@gmail.com. Agarwalla Sanjib Kumar, Harish-Chandra Research Institute, Chhatnag Road,. Jhunsi, Allahabad 211 019, India sanjib@mri.ernet.in. Alok Ashutosh Kumar, Department of Theoretical Physics, ...

  7. The Variable Quiescent X-Ray Emission of the Neutron Star Transient XTE J1701-462

    NARCIS (Netherlands)

    Fridriksson, Joel K.; Homan, J.; Wijnands, R.; Cackett, E. M.; Degenaar, N.; Mendez, M.; Altamirano, D.; Brown, E. F.; Belloni, T. M.; Lewin, W. H. G.

    We have monitored the cooling of the neutron star in the transient low-mass X-ray binary XTE J1701-462 with Chandra and XMM-Newton since the source entered quiescence in 2007 after an exceptionally luminous 19-month outburst. A recent Chandra observation made almost 1200 days into quiescence

  8. Resonance – Journal of Science Education | Indian Academy of ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Chandra Das. Articles written in Resonance – Journal of Science Education. Volume 19 Issue 5 May 2014 pp 446-465 General Article. Projectile Motion with Quadratic Damping in a Constant Gravitational Field · Chandra Das Dhiranjan Roy · More Details Fulltext ...

  9. The legacy of S Chandrasekhar (1910–1995)

    Indian Academy of Sciences (India)

    tures on quantum mechanics. Although Chandra had studied Dirac's book on his own, he attended his lectures faithfully, even though Dirac essentially copied onto the blackboard from his book. Dirac became his official advisor during the second term when Fowler left. Cambridge on sabbatical and Chandra came to know ...

  10. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics. Bikash Chandra Paul. Articles written in Pramana – Journal of Physics. Volume 71 Issue 6 December 2008 pp 1247-1257 Research Articles. Anisotropic Bianchi-I universe with phantom field and cosmological constant · Bikash Chandra Paul Dilip Paul · More Details Abstract ...

  11. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. B P Chandra. Articles written in Bulletin of Materials Science. Volume 26 Issue 5 August 2003 pp 537-541 Polymers. Photoplastic effect in polycarbonate using microhardness measurements · R Bajpai Sandhya Sharma V K Vastal B P Chandra · More Details Abstract Fulltext ...

  12. R-~-ONANCE--IAUg-US-t-19-9-6

    Indian Academy of Sciences (India)

    to paint, although later he gave up painting altogether. Contact with Prof. K S Krishnan at Allahabad. University during his M.Sc. changed his future. Prof. Krishnan was quick to recognize. Harish-Chandra's extraordinary mathematical skills and encouraged him to take up physics as a career. Harish-Chandra was persuaded ...

  13. Browse Author Index

    African Journals Online (AJOL)

    Items 101 - 142 of 142 ... Sekaran, Chandra Bala · Sekharan, Chandra Bala · Seshamamba, Burla Sunitha Venkata · Simpson, GB · Singh, Manisha · Sreekumaran, E · Sri Sai, Tejaswini M · Sridevi, K · Srivastava, P · Srivastava, S · Sultan, OM · Sultan, SO · Sundaramurthy, MI · Sunil, Atkuru Veera Venkata Naga Krishna

  14. Resonance – Journal of Science Education | Indian Academy of ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Pramod Chandra P Bhatt. Articles written in Resonance – Journal of Science Education. Volume 19 Issue 6 June 2014 pp 549-569 General Article. What's New in Computers: Cryptocurrencies: An Introduction · Pramod Chandra P Bhatt · More Details Fulltext PDF ...

  15. Unlocking Insights about Military Children and Families

    Science.gov (United States)

    Chandra, Anita; London, Andrew S.

    2013-01-01

    As this issue of the "Future of Children" makes clear, there is much yet to learn about military children and their families. A big part of the reason, write Anita Chandra and Andrew London, is the lack of sufficiently robust sources of data. Until more and better data are collected about military families, Chandra and London say, it…

  16. Dislocation unpinning model of acoustic emission from alkali halide ...

    Indian Academy of Sciences (India)

    Dislocation unpinning model of acoustic emission from alkali halide crystals. B P CHANDRA1, ANUBHA S GOUR1, VIVEK K CHANDRA2 and YUVRAJ PATIL3. 1School of Studies in Physics, Pt. Ravi Shankar Shukia University, Raipur 492 010, India. 2Department of Electronics and Telecommunication, Raipur Institute of ...

  17. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics. B P Chandra. Articles written in Pramana – Journal of Physics. Volume 54 Issue 2 February 2000 pp 287-303 Research Articles. Correlation between deformation bleaching and mechanoluminescence in coloured alkali halide crystals · B P Chandra M Ramrakhiani P Sahu ...

  18. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. K Chandra. Articles written in Bulletin of Materials Science. Volume 30 Issue 4 August 2007 pp 309-314 Biomaterials. Characteristics of porous zirconia coated with hydroxyapatite as human bones · V V Narulkar S Prakash K Chandra · More Details Abstract Fulltext PDF.

  19. The faint neutron star soft X-ray transient SAX J1810.8-2609 in quiescence

    NARCIS (Netherlands)

    Jonker, P.G.; Wijnands, R.; van der Klis, M.

    2004-01-01

    We present the analysis of a 35-ksec-long Chandra observation of the neutron star soft X-ray transient (SXT) SAX J1810.8-2609. We detect three sources in the field of view. The position of one of them is consistent with the location of the ROSAT error circle of SAX J1810.8-2609. The accurate Chandra

  20. Journal of Biosciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Biosciences. Praveen Chandra Verma. Articles written in Journal of Biosciences. Volume 36 Issue 1 March 2011 pp 153-161 Articles. RNA interference for the control of whiteflies (Bemisia tabaci) by oral route · Santosh Kumar Upadhyay K Chandrashekar Nidhi Thakur Praveen Chandra Verma J ...

  1. Record of Lower Gondwana megafloral assemblage from Lower ...

    Indian Academy of Sciences (India)

    Madhu

    The floristic composition suggests that a warm and humid climate prevailed during the Late Permian. The status of the Kamthi Formation in ... Diamictite, greenish sandstone, olive and chocolate coloured needle shales and ...... Palaeobotanist 31 208–212. Chandra S and Chandra A 1988 Vegetational changes and their cli-.

  2. G359.97-0.038: A Hard X-Ray Filament Associated with a Supernova Shell-Molecular Cloud Interaction

    DEFF Research Database (Denmark)

    Nynka, Melania; Hailey, Charles J.; Zhang, Shuo

    2015-01-01

    wind nebula (PWN) in high-resolution Chandra imaging, our spatially resolved Chandra spectral analysis found no significant spectral softening along the filament as would be expected from particle synchrotron cooling. Coincident radio emission is detected using the Very Large Array at 5.5 and 8.3 GHz...

  3. Editorial -R-5-0-NA-NCEIAU-9-US-tl-9-96

    Indian Academy of Sciences (India)

    father was always very deeply rooted in. India". - on Harish-Chandra by his daughter by Rajat Tandon. Harish-Chandra was the greatest Indian mathematician since Srinivasa Ramanujan. Though he grew up in India, and began his research career as a theoretical physicist working with Homi Jehangir Bhabha at the Indian.

  4. Studies of dark energy with X-ray observatories.

    Science.gov (United States)

    Vikhlinin, Alexey

    2010-04-20

    I review the contribution of Chandra X-ray Observatory to studies of dark energy. There are two broad classes of observable effects of dark energy: evolution of the expansion rate of the Universe, and slow down in the rate of growth of cosmic structures. Chandra has detected and measured both of these effects through observations of galaxy clusters. A combination of the Chandra results with other cosmological datasets leads to 5% constraints on the dark energy equation-of-state parameter, and limits possible deviations of gravity on large scales from general relativity.

  5. A new genus of leafhopper subtribe Paraboloponina (Hemiptera: Cicadellidae) with molecular phylogeny of related genera.

    Science.gov (United States)

    Meshram, Naresh M; Shashank, Pathour R; Sinha, Twinkle

    2017-01-01

    A new leafhopper genus Chandra and species Chandra dehradunensis gen. nov., sp. nov. are described, illustrated from India and placed in the subtribe Paraboloponina (Cidadellidae: Deltocephalinae: Drabescini). This genus is closely associated with the genus Parabolopona Webb but differs in shape of the head, placement of antennae, male genitalia and molecular analysis using Histone H3 and COI genes confirmed the difference. The taxonomic and phylogenetic position of Chandra is discussed using morphological characters and preliminary molecular evidence of the new genus and related genus Parabolopona.

  6. S Chandrasekhar the man behind the legend

    CERN Document Server

    1997-01-01

    Subrahmanyan Chandrasekhar - known simply as Chandra throughout the scientific world - has become a legendary figure for his prolific contributions to physics, astrophysics, and applied mathematics. Before his death in 1995, Chandra had forbidden a memorial of the conventional sort, celebrating his life. This book, which contains some thirty articles by his former students, his associates, and his colleagues, is in a sense a memorial volume. It says little about Chandra's great scientific achievements, but shows his human side and the various facets of his brilliant personality, his incredible

  7. What We Have Learned About Clusters From a Decade of Arcsecond Resolution X-ray Observations

    Science.gov (United States)

    Markevitch, Maxim

    2012-01-01

    This talk will briefly review the main findings from Chandra high angular resolution observations of galaxy clusters, emphasizing results on cluster astrophysics. Chandra has discovered shock fronts in merging systems, providing information on the shock Mach number and velocity, and for best-observed shocks, constraining the microphysical properties of the intracluster medium (ICM). Cold fronts, a Chandra discovery, are ubiquitous both in merging clusters and in the cool ccres of relaxed systems. They reveal the structure and strength of the intracluster magnetic fields and constrain the ICM viscosity a combined with radio data, these observations also shed light on the production of ultra-relativistic particles that are known to coexist with thermal plasma. Finally, in nearly all cool cores, Chandra observes cavities in the ICM that are produced by the central AGN. All these phenomena will be extremely interesting for high-resolution SZ studies.

  8. Search for an interstellar Si2C molecule: A theoretical prediction

    Indian Academy of Sciences (India)

    Author Affiliations. Suresh Chandra1. School of Physical Sciences, SRTM University, Nanded 431 606, India Visiting Associate, Inter-University Centre for Astronomy and Astrophysics, Pune 411 007, India ...

  9. On Erdos–Wood's conjecture

    Indian Academy of Sciences (India)

    Woods conjecture with = 2 is at least /(log ) for some positive constant > 2. ... Institute of Mathematical Sciences, C.I.T. Campus, 4th Cross Street, Taramani, Chennai 600 113, India; Harish-Chandra Research Institute, Chhatnag Road, ...

  10. Acknowledgment

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Acknowledgment. My Recent/Current PhD Students. Dr. Subimal Ghosh. Dr. Deepashree Raje. Dr. Shaik Rehana. Ms. Arpita Mondal. Mr. Ujjwal Saha. Ms. Chandra Rupa.

  11. Demography of High-Redshift AGN

    Directory of Open Access Journals (Sweden)

    Fabrizio Fiore

    2012-01-01

    Universe during its infancy. We review the latest searches for high-z AGN in the deepest X-ray field so far, the Chandra Deep Field South (CDFS 4 Msecond exposure. We do not confirm the positive detection of a signal in the stacked Chandra images at the position of z~6 galaxies recently reported by Treister and collaborators (2011. We present z>3 X-ray sources number counts in the 0.5–2 keV band, obtained joining CDFS faint detections (see Fiore et al. (2011, with Chandra-COSMOS and XMM-COSMOS detections. We use these number counts to make predictions for surveys with three mission concepts: Athena, WFXT, and a Super-Chandra.

  12. Overcoming heat shock protein inhibition at critical temperature vital ...

    African Journals Online (AJOL)

    Overcoming heat shock protein inhibition at critical temperature vital for survival in Solanum tuberosum L. in vivo condition. Bengyella Louis, Pranab Roy, Tamgue Ousman, Sayanika Waikhom Devi, Narayan Chandra Talukdar ...

  13. A Novel Mitochondria-Dependent Apoptotic Pathway (MAP) in Prostate Cancer (Pca) Cells

    National Research Council Canada - National Science Library

    Chandra, Dhyan

    2004-01-01

    ...) are also up-regulated (Chandra et al., J. Biol. Chem., 277, 50842-54; 2002). Later, when the apoptotic machinery is activated, I notice that there is prominent localization of active caspase-9 and -3 in the mitochondria...

  14. Use of electrophilic coupling reagents, 3-methyl-2 ...

    African Journals Online (AJOL)

    Use of electrophilic coupling reagents, 3-methyl-2-benzothiazolinone hydrazone hydrochloride and 4-amino antipyrine, for the spectrophotometric analysis of vardenafil in tablet dosage forms. Atkuru Veera Venkata Naga Krishna Sunil, Chandra Bala Sekaran, Tamanampudi Varahala Reddy ...

  15. Enhancement of proton conductivity of sulfonated polystyrene ...

    Indian Academy of Sciences (India)

    Enhancement of proton conductivity of sulfonated polystyrene membrane prepared by plasma polymerization process. BHABESH KUMAR NATH, AZIZ KHAN, JOYANTI CHUTIA. ∗. , ARUP RATAN PAL,. HEREMBA BAILUNG, NEELOTPAL SEN SARMA, DEVASISH CHOWDHURY and NIRAB CHANDRA ADHIKARY.

  16. 77 FR 67028 - NASA Advisory Council; Information Technology Infrastructure Committee; Meeting

    Science.gov (United States)

    2012-11-08

    ... Research Human Space Flight Operations at Marshall Space Flight Center Chandra/X-Ray Astronomy Mobile... SPACE ADMINISTRATION NASA Advisory Council; Information Technology Infrastructure Committee; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of meeting. SUMMARY: In accordance...

  17. Focus Area Science Technology Summer Fellowship (FAST-SF)

    Indian Academy of Sciences (India)

    Home; Fellowship. Fellow Profile. Elected: 1935 Section: Earth & Planetary Sciences. Roy, Sures Chandra FNA. Date of birth: 1 March 1899. Date of death: 9 December 1970. Specialization: Meteorology, Seismology. YouTube; Twitter; Facebook; Blog ...

  18. Estimates of genetic parameters of fruit quality traits in teasle gourd ...

    African Journals Online (AJOL)

    aghomotsegin

    2014-01-08

    Jan 8, 2014 ... 1Department of Vegetable Crops, Faculty of Horticulture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia-. 741252, West Bengal, India. 2Department of Horticulture (Vegetable and Floriculture), Bihar Agricultural University, Sabour, Bhagalpur-813210, Bihar,. India. Accepted 2 December, 2013.

  19. Molecular investigations on grain filling rate under terminal heat ...

    African Journals Online (AJOL)

    Molecular investigations on grain filling rate under terminal heat stress in bread wheat (Triticum aestivum L.) Girish Chandra Pandey, Jagadish Rane, Sindhu Sareen, Priyanka Siwach, NK Singh, Ratan Tiwari ...

  20. ACKNOWLEDGEMENTS

    Indian Academy of Sciences (India)

    Unknown

    Kenneth Carpenter, Colorado. Jacques Castanet, Paris. P Chakraborty, Chandigarh. Animesh Chakravorty, Jadavpur. H Sharat Chandra, Bangalore. Sosale Chandrasekhar, Bangalore. M K Chandrashekaran, Bangalore. Sumantra Chatterji, Bangalore. Hueng S Choi, Kwangju. Matthew Cobb, Paris. Athel Cornish-Bowden ...

  1. Projectile Motion with Quadratic Damping in a Constant ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 5. Projectile Motion with Quadratic Damping in a Constant Gravitational Field. Chandra Das Dhiranjan Roy. General Article Volume 19 Issue 5 May 2014 pp 446-465 ...

  2. Relativistic effects on the modulational instability of electron plasma ...

    Indian Academy of Sciences (India)

    Author Affiliations. Basudev Ghosh1 Swarniv Chandra1 Sailendra Nath Paul1 2. Department of Physics, Jadavpur University, Kolkata 700 032, India; Centre for Science Education and Research, P-1 B.P. Township, Kolkata 700 094, India ...

  3. Feministiske Tænkere

    DEFF Research Database (Denmark)

    Nay, Bronwyn Davies, Chandra Talpade Mohanty, Oyeronke Oyewumi, Sandra Harding og Donna Haraway. Teksterne i Feministiske Tænkere falder under fire hovedtemaer, nemlig Queerfeminisme, Forandring handling og subjektivitet, Postkolonial feministisk kritik og videnskabsteori. Hvert tema indledes af en...

  4. Distribution of residues and primitive roots

    Indian Academy of Sciences (India)

    Author Affiliations. Jagmohan Tanti1 R Thangadurai2. Central University of Jharkhand, CTI Campus, Ratu-Lohardaga Road, Brambe, Ranchi 835 205, India; 2Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019, India ...

  5. Microstructures using RF sputtered PSG film as a sacrificial layer in ...

    Indian Academy of Sciences (India)

    Author Affiliations. Vivekanand Bhatt1 Sudhir Chandra1 Chatar Singh2. Centre for Applied Research in Electronics (CARE), Indian Institute of Technology Delhi, New Delhi 110 016; Textile Technology, Indian Institute of Technology Delhi, New Delhi 110 016 ...

  6. J. Astrophys. Astr. (2014) 35, 745–746 Acknowledgments Journal of ...

    Indian Academy of Sciences (India)

    BetiCiciJoan

    . Gopal, Bhatta, Florida, United States. Goswami, Aruna, Bangalore, India. Gupta, Alok Chandra, Nainital, India. Iorio, Lorenzo, Bari, Italy. Janardhan, Padmanabhan, Ahmedabad, India. Joshi, Pankaj S., Mumbai, India. Joshi, Manasvita, Boston ...

  7. Bark is the Hallmark

    Indian Academy of Sciences (India)

    Author Affiliations. Dipanjan Ghosh1 2. Teacher in Botany Biological Science Department Kirnahar Shib Chandra High School Kirnahar, Birbhum 731302, West Bengal, India. Chotonilpur Pirtala Burdwan 713103, West Bengal, India.

  8. Ergonomics SA - Vol 25, No 2 (2013)

    African Journals Online (AJOL)

    A Study of Musculoskeletal Discomforts and Associated Risks among Indian Percussion (Tabla) Players · EMAIL FULL TEXT EMAIL FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. W Mishra, A De, S Gangopadhyay, AM Chandra, 2-11 ...

  9. Functional and catalytic active sites prediction and docking analysis ...

    African Journals Online (AJOL)

    Bioinformatics

    2015-07-01

    Jul 1, 2015 ... docking analysis of azoreductase enzyme in. Pseudomonas putida with a variety of commercially available azodyes. Bikash Thakuria, Chandra J Singha, Premchand Maisnam and Samrat Adhikari*. Bioinformatics Centre, Department of Biotechnology, St. Edmund's College, Shillong, Meghalaya, India.

  10. Nuclear Medicine Physics: The Basics. 7th ed.

    Science.gov (United States)

    Mihailidis, Dimitris

    2012-10-01

    Nuclear Medicine Physics: The Basics. 7th ed. Ramesh Chandra, Lippincott Williams and Wilkins, a Wolters Kluwer Business. Philadelphia, 2012. Softbound, 224 pp. Price: $69.99. ISBN: 9781451109412. © 2012 American Association of Physicists in Medicine.

  11. STS-93: Crew Interview - Cady Coleman

    Science.gov (United States)

    1999-01-01

    Live footage of a preflight interview with Mission Specialist Catherine G. Coleman is presented. The interview addresses many different questions including why Coleman wanted to be an astronaut, why she wanted to become a chemist, and how this historic flight (first female Commander of a mission) will influence little girls. Other interesting information that this one-on-one interview discusses is the deployment of the Chandra satellite, why people care about x ray energy, whether or not Chandra will compliment the other X Ray Observatories currently in operation, and her responsibilities during the major events of this mission. Coleman mentions the Inertial Upper Stage (IUS) rocket that will deploy Chandra, and the design configuration of Chandra that will allow for the transfer of information. The Southwest Research Ultraviolet Imaging System (SWUIS) Telescope on board Columbia, the Plant Growth Investigation in Microgravity (PGIM) experiment, and the two observatories presently in orbit (Gamma Ray Observatory, and Hubble Space Telescope) are also discussed.

  12. Effect of caffeine on the intraocular pressure in patients with primary open angle glaucoma

    OpenAIRE

    Chandra P; Gaur A; Varma S

    2011-01-01

    Peeyush Chandra1, Ajit Gaur1, Shambhu Varma21Chandra Eye Research Institute, Allahabad, UP, India; 2Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USAPurpose: Coffee and tea are very common nonalcoholic beverages. However, their intake, particularly that of coffee, has been suggested to increase intraocular pressure (IOP) in patients with open angle glaucoma/ocular hypertension. The causative agent has been suggested to be their caff...

  13. Tribute to Nirbhaya (Fearless

    Directory of Open Access Journals (Sweden)

    Rituparna Bhattacharyya

    2013-05-01

    Full Text Available We are happy to launch the first issue of the Journal Space and Culture, India.  This first issue is a tribute to Nirbhaya (Fearless, who was brutally gang-raped and left in a ‘vegetative state’ to die, who subsequently succumbed to her injuries on December 29, 2012. Alongside, we also pay our last respect to Chief Justice Jagdish Charan Verma (January 18, 1933 – April 22, 2013, who headed the government-appointed panel, Justice Verma Committee that came out with the recommendations on enhancing women’s safety and security.The journal is very grateful to all the members of the editorial board for their strong commitment and support. We also thank the contributors of the first issue. We are committed to encourage young scholars and researchers to submit their theoretically informed original research, commentaries and reviews on any social issues of India and make an impact to the society.We understand that your research is very important to you - we guarantee global distribution accessible universally on-line and without any charge. We are in the process of obtaining International Standard Serial Number (ISSN from ISSN UK centre, British Library. The journal will also be registered with the official Open Archives registry, UIUC OAI registry, Social Science Research Network (SSRN and OAIster so that the articles are indexed within a globally distributed system of research databases. The journal will also contribute to certain Libraries participating in the LOCKSS (Lots of Copies Keep Stuff Safe system to ensure a secure and permanent archive for the journal. In addition, content of the journal will be indexed by Google Scholar and other search engines and also will be registered with Index Copernicus and other indexing system.Looking forward to your valuable contributions! Happy reading!Thank you,Executive Editor, Space and Culture, India

  14. Development of a potent invigorator of immune responses endowed with both preventive and therapeutic properties

    Directory of Open Access Journals (Sweden)

    Talwar GP

    2017-05-01

    Full Text Available Gursaran P Talwar,1 Jagdish C Gupta,1 Abu S Mustafa,2 Hemanta K Kar,3 Kiran Katoch,4 Shreemanta K Parida,5 Prabhakara P Reddi,6 Niyaz Ahmed,7 Vikram Saini,8 Somesh Gupta9 1Talwar Research Foundation, New Delhi, India; 2Department of Microbiology, Kuwait University, Kuwait; 3Department of Dermatology, Paras Hospital, Gurgaon, 4National JALMA Institute of Leprosy and Other Mycobacterial Diseases, Agra, India; 5German Centre of Infection, Justus Liebig University, Giessen, Germany; 6Department of Comparative Biosciences, University of Illinois Urbana Champaign, IL, USA; 7Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India; 8Department of Microbiology, University of Alabama, Birmingham, AL, USA; 9Department of Dermatology and Venereology, All India Institute of Medical Sciences, New Delhi, India Abstract: This article reviews briefly the making of an immunoprophylactic-cum-immunotherapeutic vaccine against leprosy. The vaccine is based on cultivable, heat-killed atypical mycobacteria, whose gene sequence is now known. It has been named Mycobacterium indicus pranii. It has received the approval of the Drug Controller General of India and the US Food and Drug Administration. Besides leprosy, M. indicus pranii has found utility in the treatment of category II (“difficult to treat” tuberculosis. It also heals ugly anogenital warts. It has preventive and therapeutic action against SP2/O myelomas. It is proving to be a potent adjuvant for enhancing antibody titers of a recombinant vaccine against human chorionic gonadotropin, with the potential of preventing pregnancy without derangement of ovulation and menstrual regularity in sexually active women. Keywords: leprosy, tuberculosis, anogenital warts, myeloma, adjuvant

  15. Astronomical Honeymoon Continues as X-Ray Observatory Marks First Anniversary

    Science.gov (United States)

    2000-08-01

    NASA's Chandra X-ray Observatory celebrates its initial year in orbit with an impressive list of firsts. Through Chandra's unique X-ray vision, scientists have seen for the first time the full impact of a blast wave from an exploding star, a flare from a brown dwarf, and a small galaxy being cannibalized by a larger one. Chandra is the third in NASA's family of great observatories, complementing the Hubble Space Telescope and the Compton Gamma Ray Observatory. "Our goal is to identify never-before-seen phenomena, whether they're new or millions of years old. All this leads to a better understanding of our universe, " said Martin Weisskopf, chief project scientist for the Chandra program at NASA's Marshall Space Flight Center, Huntsville, AL. "Indeed, Chandra has changed the way we look at the universe." Chandra was launched in July 1999. After only two months in space, the observatory revealed a brilliant ring around the heart of the Crab Pulsar in the Crab Nebula ­ the remains of a stellar explosion ­ providing clues about how the nebula is energized by a pulsing neutron, or collapsed, star. Chandra also detected a faint X-ray source in the Milky Way galaxy, which may be the long-sought X-ray emission from the known massive black hole at the galaxy's center. A black hole is a region of space with so much concentrated mass there is no way for a nearby object, even light, to escape its gravitational pull. The observatory captured as well an image that revealed gas funneling into a massive black hole in the heart of a galaxy, two million light years from our own Milky Way, is much cooler than expected. "Chandra is teaching us to expect the unexpected about all sorts of objects ranging from comets in our solar system and relatively nearby brown dwarfs to distant black holes billions of light years away," said Harvey Tananbaum, director of the Chandra X-ray Center in Cambridge, MA. Perhaps one of Chandra's greatest contributions to X-ray astronomy is the resolution

  16. Mystery of Cometary X-Rays Solved

    Science.gov (United States)

    2000-07-01

    On July 14, 2000 NASA's Chandra X-ray Observatory imaged Comet C/1999 S4 (LINEAR) and detected X-rays from oxygen and nitrogen ions. The details of the X-ray emission, as recorded on Chandra's Advanced CCD Imaging Spectrometer, show that they are produced by collisions of ions racing away from the Sun with gas in the comet. "This observation solves one mystery. It proves how comets produce X-rays," said Dr. Carey Lisse of the Space Telescope Science Institute (STScI) leader of a team of scientists from STScI, NASA's Goddard Space Flight Center, Max Planck Institute in Germany, Johns Hopkins University, the University of California, Berkeley, and the Harvard-Smithsonian Center for Astrophysics. "With an instrument like Chandra, we can now study the chemistry of the solar wind, and observe the X-ray glow from the atmospheres of comets as well as planets such as Venus. It may even be possible to observe other, nearby solar systems." Comets, which resemble "dirty snow balls" a few miles in diameter, were thought to be too cold for such energetic emission, so the detection of X-rays by the ROSAT observatory from comet Hyakutake in 1996 was a surprise. Several explanations were suggested, but the source of cometary X-ray emission remained a puzzle until the Chandra observation of Comet C/1999 S4 (LINEAR). Chandra's imaging spectrometer revealed a strong X-ray signal from oxygen and nitrogen ions, clinching the case for the production of X-rays due to the exchange of electrons in collisions between nitrogen and oxygen ions in the solar wind and electrically neutral elements (predominantly hydrogen) in the comets atmosphere. The Chandra observation was taken with the Advanced CCD Imaging Spectrometer (ACIS) on July 14, 2000 for a total of 2 ½ hours. The comet will be re-observed with Chandra during the weeks of July 29 - Aug 13. Comet C/1999 S4 (LINEAR) was discovered in September 1999 by the Lincoln Near Earth Asteroid Research (LINEAR) project, which is operated by the

  17. The 3C111 Jet: X-ray Variability, Spectrum & Broadband SED

    Science.gov (United States)

    Perlman, Eric

    2017-08-01

    The discovery of X-ray emission from AGN jets is a touchstone of the Chandra mission. Their X-ray emission processes have become the source of much debate, with implications for both jet physics and cluster feedback models. 3C111 has an extraordinary 2-arcminute long jet that is seen in X-ray, near-IR and radio. At least 8 knots, plus both approaching and receding hotspots and lobes, are seen in the Chandra image. We request additional Chandra, HST and NuSTAR observations, to follow up on possible evidence of variability in two knots, pin down the knots' X-ray spectrum and SED, detect the jet above 10 keV, and study the morphology and X-ray spectrum of the extended lobes. These observations will place the tightest constraints yet on the physics of this fascinating system.

  18. X-ray detection of the old nova DK Lacertae

    Science.gov (United States)

    Boardman, S. F.; Takei, D.; Drake, J. J.; Sakamoto, T.; Fruscione, A.

    2016-01-01

    We report the detection of the old nova DK Lacertae with Chandra X-Ray Observatory's ACIS-S CCD imaging spectrometer on 3 February 2015. DK Lacertae, located at (J2000) 22:49:46.970 +53:17:19.66, was discovered in 1950 at a brightness of 6 mag (Bertaud, C., 1950, IAUC, 1254, 1). Chandra detected 92.5 +/- 9.6 net counts from the source at a count rate of 0.0306 +/- 0.0032 c/s over an exposure time of 3025.6 s. No significant variability was observed during the length of the observation.

  19. Eigenvalues of Bethe vectors in the Gaudin model

    Science.gov (United States)

    Molev, A. I.; Mukhin, E. E.

    2017-09-01

    According to the Feigin-Frenkel-Reshetikhin theorem, the eigenvalues of higher Gaudin Hamiltonians on Bethe vectors can be found using the center of an affine vertex algebra at the critical level. We recently calculated explicit Harish-Chandra images of the generators of the center in all classical types. Combining these results leads to explicit formulas for the eigenvalues of higher Gaudin Hamiltonians on Bethe vectors. The Harish-Chandra images can be interpreted as elements of classical W-algebras. By calculating classical limits of the corresponding screening operators, we elucidate a direct connection between the rings of q-characters and classical W-algebras.

  20. The Future of X-Ray Optics

    Science.gov (United States)

    Weisskopf, Martin C.

    2013-01-01

    The most important next step is the development of X-ray optics comparable to (or better than) Chandra in angular resolution that far exceed Chandra s effective area. Use the long delay to establish an adequately funded, competitive technology program along the lines I have recommended. Don't be diverted from this objective, except for Explorer-class missions. Progress in X-ray optics, with emphasis on the angular resolution, is central to the paradigm-shifting discoveries and the contributions of X-ray astronomy to multiwavelength astrophysics over the past 51 years.

  1. Approximation of Signals (Functions by Trigonometric Polynomials in Lp-Norm

    Directory of Open Access Journals (Sweden)

    M. L. Mittal

    2014-01-01

    trigonometric-Fourier approximation (tfa for the situations in which the summability matrix T does not have monotone rows. In this paper, the first author continues the work in the direction for T to be a Np-matrix. We extend two theorems on summability matrix Np of Deger et al. (2012 where they have extended two theorems of Chandra (2002 using Cλ-method obtained by deleting a set of rows from Cesàro matrix C1. Our theorems also generalize two theorems of Leindler (2005 to Np-matrix which in turn generalize the result of Chandra (2002 and Quade (1937.

  2. Cold Probes of the Hot Universe

    Science.gov (United States)

    Kilbourne, Caroline

    2017-01-01

    In this image, data from NASA's Spitzer, Hubble, and Chandra satellites are combined. Optical light from stars (yellow-greenHubble) shows the disk of an apparently normal galaxy. Another Hubble observation designed to image 10,000 K hydrogen gas (orange) reveals matter blasting out of the galaxy. The Spitzer infrared image (red) shows that cool gas and dust are also being ejected. Chandra's X-ray image (blue) reveals gas that has been heated to millions of degrees by the violent outflow.

  3. Nature vs. Nurture: The influence of OB star environments on proto-planetary disk evolution

    Science.gov (United States)

    Bouwman, Jeroen

    2006-09-01

    We propose a combined IRAC/IRS study of a large, well-defined and unbiased X-ray selected sample of pre-main-sequence stars in three OB associations: Pismis 24 in NGC 6357, NGC 2244 in the Rosette Nebula, and IC 1795 in the W3 complex. The samples are based on recent Chandra X-ray Observatory studies which reliably identify hundreds of cluster members and were carefully chosen to avoid high infrared nebular background. A new Chandra exposure of IC 1795 is requested, and an optical followup to characterise the host stars is planned.

  4. Mrs. Chandrasekhar addresses the media in TRW Media Hospitality Tent

    Science.gov (United States)

    1999-01-01

    Mrs. Lalitha Chandrasekhar (right), wife of the late Indian- American Nobel Laureate Subrahmanyan Chandrasekhar, addresses the media and other invited guests in the TRW Media Hospitality Tent at the NASA Press Site at KSC as Dr. Alan Bunner, Science Program Director, Structure and Evolution of the Universe, Office of Space Science, NASA Headquarters, Washington, D.C., looks on. The name 'Chandra,' a shortened version of her husband's name which he preferred among friends and colleagues, was chosen in a contest to rename the Advanced X-ray Astrophysics Facility. 'Chandra' also means 'Moon' or 'luminous' in Sanskrit. The observatory is scheduled to be launched aboard Columbia on Space Shuttle mission STS-93.

  5. Climate change effects on Glacier recession in Himalayas using Multitemporal SAR data and Automatic Weather Station observations

    Science.gov (United States)

    Kumar, V.; Singh, S. K.; Venkataraman, G.

    2009-04-01

    The Himalaya is the highest but the youngest mountain belt (20 to 60 million years B.P.) of the earth running in arc shape for about 2500 km. It has more than 90 peaks above 6000 m and contains about 50% of all glaciers outside of the polar environments (Bahadur, 1993). All glaciers in this region are in general recession since last 150 years (Paul et al.,1979). Gangotri, Siachen, Bara Shigri and Patsio are major glaciers in this region which are showing retreat with different rates and their respective tributary glaciers are completely disconnected from main body of glaciers. Spaceborne synthetic aperture radar data provide an important tool for monitoring the fluctuation of the glaciers. In this paper attempt has been made for quantifying the glacier retreat using multitemporal synthetic aperture radar (SAR) data. SAR intensity and phase information will be exploited separately under SAR intensity tracking and interferometric SAR (InSAR) coherence tracking (Strozzi et al., 2002) respectively. Glacier retreat study have been done using time series coregistered multi temporal SAR images. Simultaneously InSAR coherence thresholding is applied for tracking the snout of Gangotri glacier. It is observed that glacier is retreating at the rate of 21 m/a. Availability of high resolution spotlight mode TerraSAR-X SAR data will supplement the ENVISAT ASAR and ERS-1/2 based observations. The observatory in the proximity of Gangotri glacier has been made functional at Bhojbasa and all weather parameters viz. Snow fall, temperature, pressure, air vector, column water vapor and humidity are recorded twice a day as per WMO standards manually and automatically. Three Automatic Weather Stations (AWS) have been established in the glacier area at Bhojbasa , Kalindipass and Nandaban. Since Himalayan environment is presently under great stress of decay and degeneration, AWS data will be analyzed in the context of climate change effects on fluctuation of glaciers. References 1.Jagdish

  6. Typing supernova remnants using X-ray line emission morphologies

    NARCIS (Netherlands)

    Lopez, L.A.; Ramirez-Ruiz, E.; Badenes, C.; Huppenkothen, D.; Jeltema, T.E.; Pooley, D.A.

    2009-01-01

    We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring the morphology of the Chandra X-ray line emission in 17 Galactic and Large Magellanic Cloud SNRs with a multipole expansion analysis (using power ratios), we find that the core-collapse SNRs

  7. Dirac equation with spin symmetry for the modified Pöschl–Teller ...

    Indian Academy of Sciences (India)

    equipment for the analysis of cultural heritage. 313. Chakraborty A see Sudarshan M. 241. Chandra Hem see Upadhyay Sanjay. 183. Chatterjee J M see Gupta D. 345. Chen Jiao-Kai. Separation of different wave components in the Bethe–Salpeter wave function. 397. Chettle D R. In vivo applications of X-ray fluorescence.

  8. Author Index S¯adhan¯a Vol. 39, 2014

    Indian Academy of Sciences (India)

    419. Chandorkar M C see Joshi B M. 391. Chandra Murthy A R see Gopinath S. 1497. Charde N. Exploring the electrodes alignment and mush- rooming effects on weld geometry of dissimilar steels during the spot welding process 1563. Charles Raja S. Transaction charges allocation using sensitivity factor methodology.

  9. Photometry of Karin family asteroids

    NARCIS (Netherlands)

    Hahn, G.; Mottola, S.; Sen, A. K.; Harris, A. W.; Kührt, E.; Mueller, M.

    2006-01-01

    We have performed photometric observations in the V-band of two asteroids belonging to the Karin asteroid family, (11728) Einer and (93690) 2000 VE21 , using the 2-m Himalayan Chandra Telescope, Hanle and 2k ×4k pixels CCD imager. We obtained measurements during two nights (November 25 and 26, 2005)

  10. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Home; Journals; Pramana – Journal of Physics. Mani Chandra. Articles written in Pramana – Journal of Physics. Volume 81 Issue 4 October 2013 pp 617-629 Research Articles. Benchmarking and scaling studies of pseudospectral code Tarang for turbulence simulations · Mahendra K Verma Anando ...

  11. Effect of alloying with zinc on SFE of aluminium by study of lattice ...

    Indian Academy of Sciences (India)

    Unknown

    315. Effect of alloying with zinc on SFE of aluminium by study of lattice imperfections in cold worked Al–Zn alloys. G KARMAKAR, R SEN†, S K CHATTOPADHYAY, A K MEIKAP and. S K CHATTERJEE*. Regional Engineering College, Durgapur 713 209, India. †Bidhan Chandra Institution, Durgapur 713 205, India.

  12. X-Ray and optical study of low core density globular clusters NGC6144 and E3

    NARCIS (Netherlands)

    Lan, S.-H.; Kong, A.K.H.; Verbunt, F.W.M.|info:eu-repo/dai/nl/068970374; Lewin, W.H.G.; Bassa, C.G.; Anderson, S.F.; Pooley, D.

    2010-01-01

    We report on the Chandra X-ray Observatory and Hubble Space Telescope (HST) observations of two low coredensity globular clusters, NGC6144 and E3. By comparing the number of X-ray sources inside the half-mass radius to those outside, we found six X-ray sources within the half-mass radius of NGC6144,

  13. X-ray sources and their optical counterparts in the Galactic Globular Cluster M12 (NGC 6218)

    NARCIS (Netherlands)

    Lu, T.-N.; Kong, A.K.H.; Bassa, C.G.; Verbunt, F.W.M.|info:eu-repo/dai/nl/068970374; Lewin, W.H.G.; Anderson, S.F.; Pooley, D.

    2009-01-01

    We study a Chandra X-ray Observatory ACIS-S observation of the Galactic globular cluster M12. With a 26 ks exposure time, we detect six X-ray sources inside the half-mass radius (2'.16) of which two are inside the core radius (0'.72) of the cluster. If we assume that these sources are all associated

  14. Working group report: Quantum chromodynamics

    Indian Academy of Sciences (India)

    Harish Chandra Research Institute, Allahabad 211 019, India; Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005, India; Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai 600 113, India; Delhi University, New Delhi 110 019, India; Deutsches Elecktronen Synchrotron DESY, Zeuthen, Germany ...

  15. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. V Ananda Rao. Articles written in Journal of Earth System Science. Volume 121 Issue 6 December 2012 pp 1455-1468. Exploring deep potential aquifer in water scarce crystalline rocks · Subash Chandra E Nagaiah D V Reddy V Ananda Rao Shakeel Ahmed · More Details ...

  16. Evaluation of portable water in five provinces of Zambia using a ...

    African Journals Online (AJOL)

    kabunga

    capacity of the soil to absorb effluent from the tank has exceeded the limit, and the waste added to the system moves upwards. Many other pathogens, such as typhoid, cholera, streptococci, salmonella, poliomyelitis, and pro- tozoans are transmitted by septic tank systems (Chandra et al., 1997). This view is further supported ...

  17. Challenges of confronting legacies of past injustices and promoting ...

    African Journals Online (AJOL)

    Brown, Stephen 2011. The national accord, impunity and the fragile peace in Kenya. Paper presented at the 6th ECPR General Conference 25–27 August, University of Iceland,. Iceland. Brown, Stephen and Chandra Sriram 2012. The big fish won't fry themselves: Criminal accountability for post-election violence in Kenya.

  18. Hydrodynamic and hydromagnetic stability of black holes with ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Subrahmanyan Chandrasekhar (Chandra) was just eight years old when the first astrophysical jet was discovered in M87. Since then, jets have been uncovered with a wide variety of sources including accretion disks orbiting stellar and massive black holes, neutron stars, isolated pulsars, -ray bursts, ...

  19. Editorial

    Indian Academy of Sciences (India)

    The classification of real compact surfaces is communicated visually in the article by Alexandru Oancea. The Harish-Chandra Research Institute has recently celebrated its silver anniversary and is profiled by Sumathi Rao. In Part 4 of the series on electronic commerce, V Rajaraman explains how secure payments using.

  20. Partnering with Your Child's School: A Guide for Parents

    Science.gov (United States)

    ... George Washington University’s Graduate School of Education and Human Development. A study was conducted by doctoral candidates Chandra ... or mental health care professionals and challenges schools face in serving ... the study informed the development of this pamphlet and are also intended to ...

  1. Marcelin berthelot and Indian alchemy.

    Science.gov (United States)

    Rosu, A

    1986-04-01

    Based on unpublished manuscripts, the article reveals the keen interest shown by Marcelin Berthelot in Indian alchemy. The French Savant has actually inspired and encouraged the first historical research in this field, undertaken at the end of the last century, in Calcutta, by the Bengali scientist Prafulla Chandra Ray.

  2. MARCELIN BERTHELOT AND INDIAN ALCHEMY

    OpenAIRE

    Rosu, Arion

    1986-01-01

    Based on unpublished manuscripts, the article reveals the keen interest shown by Marcelin Berthelot in Indian alchemy. The French Savant has actually inspired and encouraged the first historical research in this field, undertaken at the end of the last century, in Calcutta, by the Bengali scientist Prafulla Chandra Ray.

  3. GRO J1744-28, search for the counterpart: infrared photometry and spectroscopy

    NARCIS (Netherlands)

    Gosling, A.J.; Bandyopadhyay, R.M.; Miller Jones, J.C.A.; Farrell, S.A.

    2007-01-01

    Using VLT/ISAAC, we have detected two candidate counterparts to the bursting pulsar GRO J1744-28, one bright and one faint, both within the X-ray error circles found using XMM-Newton and Chandra. In determining the spectral types of the counterparts we applied three different extinction corrections;

  4. The return to quiescence of Aql X-1 following the 2010 outburst

    NARCIS (Netherlands)

    Campana, S.; Brivio, F.; Degenaar, N.; Mereghetti, S.; Wijnands, R.; D'Avanzo, P.; Israel, G.L.; Stella, L.

    2014-01-01

    Aql X-1 is the most prolific low-mass X-ray binary transient hosting a neutron star. In this paper we focus on the return to quiescence following the 2010 outburst of the source. This decay was monitored thanks to 11 pointed observations taken with XMM-Newton, Chandra and Swift. The decay from

  5. An alarming but self-limited case of isolated large spontaneous liver ...

    African Journals Online (AJOL)

    abp

    &Corresponding author: Vikal Chandra Shakya, Department of Surgery, B. P. Koirala Institute of Health Sciences, Dharan, Nepal. Key words: Liver hematoma, pregnancy, HELLP syndrome. Received: 22/06/2012 - Accepted: 21/01/2013 - Published: 25/01/2013. Abstract. Spontaneous subcapsular liver hematoma is rare but ...

  6. Heterochromatin and the molecular mechanisms of 'parent-of-origin ...

    Indian Academy of Sciences (India)

    2016-11-30

    Nov 30, 2016 ... chromatin structure (Khosla et al. 1996, 1999), histone modification (Bongiorni et al. 2009) and DNA methylation. (Bongiorni et al. 1999; Buglia et al. 1999; Mohan and. Chandra 2005). Approximately 10% of sperm chromatin is nuclease resistant (Khosla et al. 1996). The sperm and the pro-nucleus it forms ...

  7. 78th Annual Meeting | Annual Meetings | Events | Indian Academy of ...

    Indian Academy of Sciences (India)

    12.00. AMITA AGGARWAL, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow Immune mechanisms in juvenile idiopathic arthritis. 12.20. A. K. SHUKLA, Indian Institute of Science, Bengaluru Electric vehicles: constraints, concerns and challenges. 12.40. V. RAVINDRAN, Harish-Chandra Research Institute ...

  8. Gravitational waves from binary black holes

    Indian Academy of Sciences (India)

    view of the Universe goes hand in hand with the experimenters hell of GW being almost impossible to detect. In the 1916 paper exploring the physical implications of GR .... proved to be a barrier for extension of the treatment to higher PN orders. Chandra (and. Thorne) did not find the infinities worrying because they felt they ...

  9. Pop / Tõnu Kaalep

    Index Scriptorium Estoniae

    Kaalep, Tõnu, 1966-

    2003-01-01

    Heliplaatidest: Morelenbaum2/Sakamoto "A Day in New York", Bonnie Raitt "The Best Of", Erinevad esitajad "Charlie's Angels. Full Throttle. Music from the Motion Picture", Themroc "Beyond These Things", LIL' KIM "La Bella Mafia", Sheila Chandra "The Indipop Retrospective", DJ Kayslay "The Streetsweeper vol.1", CALEXICO "Feast of Wire"

  10. The legacy of S Chandrasekhar (1910–1995)

    Indian Academy of Sciences (India)

    Subrahmanyan Chandrasekhar, known simply as Chandra in the scientific world, is one of the foremost scientists of the 20th century. In celebrating his birth centenary, I present a biographical portrait of an extraordinary, but a highly private individual unknown to the world at large. Drawing upon his own ``A Scientific ...

  11. Application of chaotic noise reduction techniques to chaotic data ...

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    neural networks. Proceedings of the Third International Seminar on Intelligent Robotic. Systems, Bangalore. Chandra Shekara Bhat C, Kaimal M R 1997 Identification and reproduction of bifurcation diagram of logistic map using ANN. Proceedings of the National Conference on Neuro-Fuzzy. Systems (New Delhi: Narosa).

  12. Fulltext PDF

    Indian Academy of Sciences (India)

    phytoalexin deficient regulators of salicylic acid signaling pathway. J. Biosci. 37 563–571. Singh N, Ranjan A, Sur S, Chandra R and Tandon V 2012 Inhibition of HIV-1 Integrase gene expression by 10–23. DNAzyme. J. Biosci. 37 493–502. Young MA, Jayaram B and Beveridge DL 1997 Intrusion of counterions into the ...

  13. Higgs production at next-to-next-to-leading order

    Indian Academy of Sciences (India)

    Higgs production at next-to-next-to-leading order. V RAVINDRAN, J sMITH and W L vAn NEERVEN. Harish-Chandra Research Institute, Jhusi, Allahabad 211 019, India. C.N. Yang Institute for Theoretical Physics, State University of New York at Stony Brook,. New York, USA. Instituut-Lorentz, University of Leiden, Leiden, ...

  14. Fellowship | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Elected: 2018 Section: Earth & Planetary Sciences. Venkataraman, Prof. Chandra Ph.D. (Univ. Calif., Los Angeles), FNAE, FNASc. Date of birth: 3 June 1963. Specialization: Aerosol Science & Engineering, Environmental & Climate Science, Atmospheric Science Address: Department of Chemical Engineering, Indian ...

  15. NuSTAR J033202-2746.8: direct constraints on the Compton reflection in a heavily obscured quasar at z ≈ 2

    DEFF Research Database (Denmark)

    Del Moro, A.; Mullaney, J. R.; Alexander, D. M.

    2014-01-01

    We report Nuclear Spectroscopic Telescope Array (NuSTAR) observations of NuSTAR J033202-2746.8, a heavily obscured, radio-loud quasar detected in the Extended Chandra Deep Field-South, the deepest layer of the NuSTAR extragalactic survey (∼400 ks, at its deepest). NuSTAR J033202-2746.8 is reliabl...

  16. Download this PDF file

    African Journals Online (AJOL)

    USER

    hard starch (75.0%) with 7.5% protein and low in fat (1.0%). It is similar to other corn species with the ... determined by titrating 20 mL of the same sample against 0.1 M Sodium hydroxide (Antony and Chandra, 1997). .... fermentation increased the content of some vital elements such as Sodium, Potassium and. Phosphorus.

  17. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    N Mahajan. Articles written in Pramana – Journal of Physics. Volume 63 Issue 6 December 2004 pp 1359-1365. Working group report: Low energy and flavour physics · Amol Dighe Anirban Kundu K Agashe B Anantanarayan A Chandra A Datta P K Das S P Das A Dighe R Forty D K Ghosh Y -Y Keum A Kundu N Mahajan S ...

  18. Author Index

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    for the GMRT, 23. Caranicolas, N. D. Comparing Maps to Symplectic Integrators in a Galactic Type. Hamiltonian, 85. Dommanget, J. The Mass/Eccentricity Limit in Double Star Astronomy, 99. Dwarakanath, K. S. see Ishwara-Chandra, C. H., 37. Gopal Rajesh Large Scale Magnetic Fields: Density Power Spectrum in Redshift.

  19. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana. P K Tripathi. Articles written in Sadhana. Volume 33 Issue 4 August 2008 pp 443-453. Design, development and performance characteristics of a large aperture disc amplifier for high power Nd: Glass laser chain · M P Kamath P K Tripathi A P Kulkarni R Chandra A S Joshi C P Navathe P D Gupta.

  20. Journal of Biosciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    pp 275-280 Articles. An allele-specific polymerase chain reaction assay for the differentiation of members of the Anopheles culicifacies complex · O P Singh Geeta Goswami N Nanda K Raghavendra D Chandra S K Subbarao · More Details Abstract Fulltext PDF. Anopheles culicifacies, the principal vector of malaria in India, ...

  1. Zero-sum problems with subgroup weights

    Indian Academy of Sciences (India)

    In this note, we generalize some theorems on zero-sums with weights from [1], [4] and [5] in two directions. In particular, we consider Z Z p d for a general and subgroups of Z p ∗ as weights. Author Affiliations. S D Adhikari1 A A Ambily2 B Sury2. Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 ...

  2. C P Navathe

    Indian Academy of Sciences (India)

    Design, development and performance characteristics of a large aperture disc amplifier for high power Nd: Glass laser chain · M P Kamath P K Tripathi A P Kulkarni R Chandra A S Joshi C P Navathe P D Gupta · More Details Abstract Fulltext PDF. A large aperture disc amplifier has been designed, set-up and characterized ...

  3. Assessment of Awareness and Knowledge of Hepatitis B among the ...

    African Journals Online (AJOL)

    San Francisco Bay Area, California. Asian Pacific. Journal of Cancer Prevention 2007; 8: 127-134. 13. Bijay Misra, Chittaranjan Panda, Haribhakti Seba Das,. Kinshuk Chandra Nayak, Shivaram Prasad Singh. Study on awareness about Hepatitis B viral infection in coastal eastern india. Hepatitis B Annual 2009;. 6(1): 19-28.

  4. Immunophenotypic enumeration of CD4 T-lymphocyte values in ...

    African Journals Online (AJOL)

    McRoy

    in human immunodeficiency virus-seronegative adults in. Eastern India. Dash M*, Padhi S, Panda P, Parida B, Patra GC. Department of Microbiology, Maharaja Krishna Chandra Gajapati Medical College and Hospital,. Berhampur University, Berhampur, Odisha, India. *Corresponding Author: mukti_mic@yahoo.co.in.

  5. One-parameter family of solitons from minimal surfaces

    Indian Academy of Sciences (India)

    School of Mathematics, Harish Chandra Research Institute, Allahabad 211 019, India. E-mail: rkmn@mri.ernet.in. MS received 29 December 2011; revised 9 February 2012. Abstract. In this paper, we discuss a one parameter family of complex Born–Infeld solitons arising from a one parameter family of minimal surfaces.

  6. The Weierstrass–Enneper representation using hodographic ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    RUKMINI DEY. School of Mathematics, Harish-Chandra Research Institute, Allahabad 211 019, India. E-mail: rkmn@mri.ernet.in. MS received 19 June 2002; revised 10 October 2002. Abstract. In this paper we obtain the general solution to the minimal surface equation, namely its local Weierstrass–Enneper representation, ...

  7. List of Participants

    Indian Academy of Sciences (India)

    rupa@mri.ernet.in. Chattopadhyay U, Tata Institute of Fundamental Research, Mumbai utpal@theory.tifr.res.in. Choubey S, Saha Institute of Nuclear Physics, Kolkata sandhya@theory.saha.ernet.in. Choudhury D, Harish-Chandra Research Institute, Allahabad debchou@mri.ernet.in. Choudhury D K, Gauhati University, ...

  8. Searching for small-scale diffuse emission around SGR 1806-20

    NARCIS (Netherlands)

    Viganò, D.; Rea, N.; Esposito, P.; Mereghetti, S.; Israel, G.L.; Tiengo, A.; Turolla, R.; Zane, S.; Stella, L.

    2014-01-01

    Diffuse radio emission was detected around the soft gamma-ray repeater SGR 1806-20  after its 2004 powerful giant flare. We study the possible extended X-ray emission at small scales around SGR 1806-20, in two observations by the High Resolution Camera Spectrometer (HRC-S) on board of the Chandra

  9. Hydrothermal synthesis of NiFe2O4 nano-particles: structural ...

    Indian Academy of Sciences (India)

    morphological, optical, electrical and magnetic properties. K CHANDRA BABU NAIDU and W ... Cole–Cole plots are drawn to study electrical conduction mechanism and the kind of relaxation—Debye or non-Debye type. ..... centres and play a key role in reducing the recombination rate of photo-induced charge carriers (e. −.

  10. Complex dynamics of a particle in an oscillating potential field

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 89; Issue 2. Complex dynamics of ... Department of Applied Mathematics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009, India; Department of Basic and Applied Science, National Institute of Technology, Arunachal Pradesh 791 112, India ...

  11. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Role of debris cover to control specific ablation of adjoining Batal and Sutri Dhaka glaciers in Chandra Basin (Himachal Pradesh) during peak ablation season · Parmanand Sharma Lavkush K Patel Rasik Ravindra Ajit Singh K Mahalinganathan Meloth Thamban · More Details Abstract Fulltext PDF. As part of the on-going ...

  12. The inactive X chromosome in the human female is enriched in 5 ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 82; Issue 1-2. The inactive X chromosome in the human female is enriched in 5-methylcytosine to an unusual degree and appears to contain more of this modified nucleotide than the remainder of the genome. Deepti D. Deobagkar H. Sharat Chandra. Volume 82 Issue 1-2 ...

  13. Sumathi Rao | Speakers | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Sumathi Rao. Sumathi Rao. Harish-Chandra Research Institute, Allahabad. Sumathi Rao received her PhD from the State University of New York at Stony Brook in 1983 in particle physics. She joined the Institute of Physics in Bhubaneswar in 1987, after postdoctoral jobs at Fermi Lab and at the University of Wisconsin in ...

  14. 104 Swinging in Imaginary Time

    Indian Academy of Sciences (India)

    IAS Admin

    104. Swinging in Imaginary Time. More on the Not-So-Simple Pendulum. Cihan Saclioglu. 116. Madhava, Gregory, Leibnitz, and Sums of Two. Squares. Shailesh A Shirali. 124. Electronic Effects in the Cyclocondensation of Benzil. G Nagendrappa. 131. Systems Biology. Karthik Raman and Nagasuma Chandra. 154.

  15. VizieR Online Data Catalog: Observed sample of z~0.7 massive galaxies (Gallazzi+, 2014)

    Science.gov (United States)

    Gallazzi, A.; Bell, E. F.; Zibetti, S.; Brinchmann, J.; Kelson, D. D.

    2017-07-01

    The sample has been selected from the COMBO-17 catalog of the Extended Chandra Deep Field South (E-CDFS) survey (Wolf et al. 2004A&A...421..913W, Cat. II/253; see also Section 2.4.1) to have photometric redshift (or spectroscopic when available) in the range 0.65=designed. (1 data file).

  16. Journal of Biosciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Clipboard: Putting T cells to sleep: a new paradigm for immune evasion by persistent viruses · Shweta Dubey Shahid Jameel · More Details Fulltext PDF. Volume 33 Issue 4 November 2008 pp 451-464. Molecular biology and pathogenesis of hepatitis E virus · Vivek Chandra Shikha Taneja Manjula Kalia Shahid Jameel.

  17. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. S Prakash. Articles written in Bulletin of Materials Science. Volume 30 Issue 4 August 2007 pp 309-314 Biomaterials. Characteristics of porous zirconia coated with hydroxyapatite as human bones · V V Narulkar S Prakash K Chandra · More Details Abstract Fulltext PDF.

  18. Chemosensory processing in the fruit fly, Drosophila melanogaster ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Biosciences; Volume 30; Issue 5. Chemosensory processing in the fruit fly, ... B C Chandra1 Sandeep Singh2. Department of Biological, Chemical and Physical Sciences, Roosevelt University, Chicago, IL 60605, USA; Department of Entomology, Ohio State University, Columbus, OH 43210, USA ...

  19. Relation between spectroscopic constants with limited Dunham ...

    Indian Academy of Sciences (India)

    Statement of Kaur and Mahajan [1] about the definition of used by Chandra [2] is not correct. Even if we take = w 2 2 r e 2 / 2 D e , the relation between and (=8ωe/) is obtained as = 4.21452856G, provided the vibrational energy of a diatomic molecule is expressed in terms of limited Dunham coefficients, ...

  20. Supporting Information.pdf

    Indian Academy of Sciences (India)

    Administrator

    Supporting information. Excited State Dynamics of 9,9´-Bianthryl in Room Temperature Ionic Liquids as. Revealed by Picosecond Time-Resolved Fluorescence Study. Dinesh Chandra Khara, Aniruddha Paul, K. Santhosh and Anunay Samanta*. School of Chemistry, University of Hyderabad, Hyderabad 500046, India.

  1. Associateship | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Fellowship; Associateship. Associate Profile. Period: 2015–2018. Prabhu, Dr Ramappa Ph.D. (Kuvempu). Date of birth: 10 June 1981. Specialization: Quantum Information Theory, Many-Body Physics, Quantum Optics Address: Harish Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019, U.P.

  2. WEST AFRICAN JOURNAL OF MEDICINE

    African Journals Online (AJOL)

    user1

    2012-07-04

    Jul 4, 2012 ... Karayalcin F, Rosner F, Kim KY,. Chandra P, Aballi AJ. Sickle cell anaemia. – clinical manifestations in 100 patients and review of the literature. Am J Med. Sci 1975; 269: 51–68. 8. Elbashier AM, Badu GA. Pattern of bacteriuria in patients with sickle cell disease in Qatif Central Hospital. Saudi. Med J. 1991 ...

  3. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    pp 447-463. Modelling, analysis, and acceleration of a printed circuit board fabrication process · K S Aithal Y Narahari E Manjunath · More Details Abstract Fulltext PDF ... pp 485-494. Application of chaotic noise reduction techniques to chaotic data trained by ANN · C Chandra Shekara Bhat M R Kaimal T R Ramamohan.

  4. Browse Title Index

    African Journals Online (AJOL)

    Items 9151 - 9200 of 11090 ... Bengyella Louis, Roy Pranab, Sayanika Devi Waikhom, Narayan Chandra Talukdar. Vol 6, No 3 (2007), Rep-PCR reveals a high genetic homogeneity among Ugandan isolates of Xanthomonas campestris pv musacearum, Abstract PDF. V Aritua, A Nanyonjo, F Kumakech, W Tushemereirwe.

  5. Browse Author Index

    African Journals Online (AJOL)

    Talukdar, Narayan Chandra · Tam, MN · Tamayo-Cortés, J · Tamayo-Ordoñez, M · Tambani, T · Tambekar, DH · Tamboura, H · Tamboura, H. H. · Tambunan, USF · Tambunan, Usman Sumo Friend · Tambunan, Usman Sumo Friend · Tamer, UA 28401 - 28450 of 33376 Items  ...

  6. African Journal of Biotechnology - Vol 12, No 8 (2013)

    African Journals Online (AJOL)

    Report of foliar necrosis of potato caused by Cochliobolus lunatus in India. Bengyella Louis, Roy Pranab, Sayanika Devi Waikhom, Narayan Chandra Talukdar. Larvicidal activity of clove (Eugenia caryophyllata) extracts and eugenol against Aedes aegypti and Anopheles darlingi · EMAIL FREE FULL TEXT EMAIL FREE ...

  7. Browse Title Index

    African Journals Online (AJOL)

    Items 7901 - 7950 of 11090 ... ... Xi-Ping Deng, Sang-Soo Kwak. Vol 11, No 47 (2012), Overcoming heat shock protein inhibition at critical temperature vital for survival in Solanum tuberosum L. in vivo condition, Abstract PDF. Bengyella Louis, Pranab Roy, Tamgue Ousman, Sayanika Waikhom Devi, Narayan Chandra Talukdar.

  8. African Journal of Biotechnology - Vol 11, No 47 (2012)

    African Journals Online (AJOL)

    ... protein inhibition at critical temperature vital for survival in Solanum tuberosum L. in vivo condition · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Bengyella Louis, Pranab Roy, Tamgue Ousman, Sayanika Waikhom Devi, Narayan Chandra Talukdar, 10769-10774 ...

  9. Report of foliar necrosis of potato caused by Cochliobolus lunatus in ...

    African Journals Online (AJOL)

    Report of foliar necrosis of potato caused by Cochliobolus lunatus in India. Bengyella Louis, Roy Pranab, Sayanika Devi Waikhom, Narayan Chandra Talukdar. Abstract. During the winter season of 2011, Cochliobolus lunatus was isolated from necrotized leaves of potato in potato plantations of Burdwan District, West ...

  10. TreePM: A Code for Cosmological N-Body Simulations

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Chandra Research Institute, Chhatnag Road, Jhunsi,. Allahabad 211 019, India. e-mail: jasjeet@mri.ernet.in. Received 2002 June 13; accepted 2002 November 14. Abstract. We describe the TreePM method for carrying out large N-Body simulations ...

  11. 18th Mid Year Meeting | Mid Year Meetings | Events

    Indian Academy of Sciences (India)

    Epidemiologic, clinical and laboratory aspects of hepatitis E, View presentation. 11.30-12.00, S. SATHEESH CHANDRA SHENOI, National Institute of Oceanography, Dona Paula, Goa Why is the Bay of Bengal warmer than the Arabian Sea? Role of ocean dynamics, View presentation. 12.00-12.30, SANDEEP SEN, Indian ...

  12. Genotoxicity Screening of Industrial Effluents using Onion bulbs ...

    African Journals Online (AJOL)

    Michael Horsfall

    hazards from a wide range of pollutants such as sewage effluents (Ukaegbu and Odeigah, 2009), leacheates (Bakare and Wale-Adeyemo, 2004,. Chandra et al., 2005) and chemicals (Seetharaman et al., 2004). Cytotoxicity and environmental pollution have been assessed by the in vivo onion (Allium cepa) root tip cell test ...

  13. Abid Kamran see Haneef Muhammad 117 Abirami K Vibrational ...

    Indian Academy of Sciences (India)

    Generalized Freud's equation and level densities with polynomial potential. 189. Bora Madhurjya P. Oscillation death in a coupled van der. Pol–Mathieu system. 677. Cabanzo Rafael see Guerrero Jáder. 987. Cai Bin see Zhang Sheng. 763. Cao Dongxu see Wu Ranchao. 727. Chandra Mani see Verma Mahendra K. 617.

  14. Fulltext PDF

    Indian Academy of Sciences (India)

    Bianchi Type-I Universe with wet dark fluid. T Singh and R Chaubey. 447–458. Anisotropic Bianchi-I universe with phantom field and cosmological con- stant. Bikash Chandra Paul and Dilip Paul. 1247–1257. Statistical Physics. Travelling wave-like solutions of the Zakharov–Kuznetsov equation with variable coefficients.

  15. Author Index

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Drake, S. A. see Pandey, J. C., 9. Duc, P.-A see Le Floc'h, E., 119. Garrett, M. A. see Gizani Nectaria, A. B., 89. Ghosh Pranab Probes of Cosmic Star Formation History, 107. Gizani Nectaria, A. B. The Multiwavelength Study of Two Unique Radio Galaxies,. 89. Holt, S. S. see Hwang, U., 81. Hwang, U. Chandra Observations ...

  16. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Proceedings of the International Conference on Physics and Astrophysics of Quark-Gluon Plasma - Part II. pp 864a-864b. Foreword · Bikash Chandra Sinha Dinesh Kumar Srivastava Yogendra Pathak Viyogi · More Details Fulltext PDF. pp 865-875. Gaseous tracking at linear hadron collider: Pushing the limits · A Sharma.

  17. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana. PALLAVIRAM SURE. Articles written in Sadhana. Volume 40 Issue 7 October 2015 pp 2111-2128. Weighted-noise threshold based channel estimation for OFDM systems · Pallaviram Sure Chandra Mohan Bhuma · More Details Abstract Fulltext PDF. Orthogonal frequency division multiplexing ...

  18. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Benchmarking and scaling studies of pseudospectral code Tarang for turbulence simulations · Mahendra K Verma Anando Chatterjee K Sandeep Reddy Rakesh K Yadav Supriyo Paul Mani Chandra Ravi Samtaney · More Details Abstract Fulltext PDF. Tarang is a general-purpose pseudospectral parallel code for ...

  19. Rotational quenching of H2CO by molecular hydrogen–Suggestion ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 88; Issue 1. Rotational quenching of H ... SURESH CHANDRA2. School of Studies in Physics, Jiwaji University, Gwalior 474 011, India; Amity Centre for Astronomy & Astrophysics, Amity Institute of Applied Sciences, Amity University, Sector-125, Noida 201 313, India ...

  20. S Chandrasekhar: His Life and Science

    Indian Academy of Sciences (India)

    Introduction. Subramanyan Chandrasekhar (or `Chandra' as he was generally known) was born at Lahore, the capital of the Punjab Province, in undivided India (and now in. Pakistan) on 19th October, 1910. He was a nephew of Sir C V Raman, who was the first Asian to get a science Nobel Prize in Physics in 1930.

  1. 2309-IJBCS-Article-Iwekumo Ebibofe Agbozu

    African Journals Online (AJOL)

    hp

    ground water. The knowledge of the composition of leachates is important to determine the dump sites that require immediate remediation attention and their ...... Acute Toxicity. Test of Leachates From Traditional And. Sustainable Landfills. Using. Luminescent Bacteria. Waste Manage., 26: 1148-1155. Singh A, Chandra S, ...

  2. Pati, Prof. Arun Kumar

    Indian Academy of Sciences (India)

    Specialization: Quantum Information Theory, Quantum Computing, Foundations of Quantum Theory Address: QIC Group, Physics Division, Harish Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad 211 019, U.P.. Contact: Office: (0532) 227 4391. Mobile: 87566 12314. Fax: (0532) 256 9576, (0532) 256 7444

  3. Dissociation energy of diatomic

    Indian Academy of Sciences (India)

    Suresh Chandra has started his comments on the presumption that we have used experimental data on De to evaluate it. This seems to be constructed on the basis of our inclusion of De experimental data in table 1 of our paper. We have not used experimental values of De as input for computations. As mentioned on page ...

  4. equatorial electrojet strength in the african sector during high and ...

    African Journals Online (AJOL)

    Preferred Customer

    Department of Geology and Geophysics, Faculty of Science, Addis Ababa University. PO Box 1176, Addis Ababa, Ethiopia, E-mail: hbeimnet@hotmail.com. ABSTRACT: The daily ..... Printing Press, Addis Ababa, Ethiopia. 2. Chandra, H., Sinha, H.S.S. and Rastogi, R.G. (2000). Equatorial electrojet studies from rocket and.

  5. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    High-Redshift Radio Galaxies from Deep Fields · C. H. Ishwara-Chandra S. K. Sirothia ... 4 December 2011 pp 613-614. Deep GMRT 150 MHz Observations of the DEEP2 Fields: Searching for High Red-Shift Radio Galaxies Revisited ... Articles are also visible in Web of Science immediately. All these have helped shorten ...

  6. DNA binding and cleavage activity of a structurally characterized Ni(II)

    Indian Academy of Sciences (India)

    SARAT CHANDRA KUMARa, ABHIJIT PALa, MERRY MITRAa ,. V M MANIKANDAMATHAVANb, CHIA -HER LINc, BALACHANDRAN UNNI NAIRb,* . and RAJARSHI GHOSHa,*. aDepartment of Chemistry, The University of Burdwan, Burdwan 713 104, India. bChemical Laboratory, Central Leather Research Institute, Adyar ...

  7. Fulltext PDF

    Indian Academy of Sciences (India)

    Sheela K Romasesha. 90 Indian Astronomy: An Introdudion. M S Sriram. 92 Trigonometric Delights. Shoilesh A Shirali. Front Cover. ':..~_. Bamboos. Back Cover. (Painting by Annapoorna Sitaram ). Acharya Prafulla Chandra Ray. (1861 - 1944). (Illustration by Anindya Das). DEPARTMENTS. Editorial. Chief Editor's Column.

  8. Editorial

    Indian Academy of Sciences (India)

    in painting an intimate portrait of his subject. There is in particular an extended and illuminating concluding dialogue between Chandra and Wali, where the former expresses himself very candidly on many issues pertinent to Indian science. One of his comments is worth recalling: " ... it is a remarkable thing that in the ...

  9. Chandrasekhar, Black Holes, and Singularities Roger Penrose

    Indian Academy of Sciences (India)

    Administrator

    Mathematical Institute, University of Oxford, Oxford 0X1 3LB, UK. 1. .... (Lifshitz and Khalatnikov had omitted a certain degree of freedom in their .... abled him to separate and decouple the equations. Chandra was a relative latecomer to the study of black holes. In his early work on white dwarf stars and the inevitability of their ...

  10. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana. T V SREENIVAS. Articles written in Sadhana. Volume 41 Issue 11 November 2016 pp 1245-1260. Optimum short-time polynomial regression for signal analysis · A SREENIVASA MURTHY CHANDRA SEKHAR SEELAMANTULA T V SREENIVAS · More Details Abstract Fulltext PDF. We propose ...

  11. What's New in Computers

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 6. What's New in Computers: Cryptocurrencies: An Introduction. Pramod Chandra P Bhatt. General Article Volume 19 Issue 6 June 2014 pp 549-569. Fulltext. Click here to view fulltext PDF. Permanent link:

  12. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Weighted-noise threshold based channel estimation for OFDM systems · Pallaviram Sure Chandra Mohan Bhuma · More Details Abstract Fulltext PDF. Orthogonal frequency division multiplexing (OFDM) technology is the key to evolving telecommunication standards including 3GPP-LTE Advanced and WiMAX. Reliability of ...

  13. Proceedings – Mathematical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    . Articles written in Proceedings – Mathematical Sciences. Volume 127 Issue 1 February 2017 pp 117-132 Research Article. On Pimsner-Popa bases · Keshab Chandra Bakshi · More Details Abstract Fulltext PDF. In this paper, we examine ...

  14. 11 Adekola, FA, Inyinbor, AA and Abdul Raheem, AMO

    African Journals Online (AJOL)

    Osondu

    2011-12-22

    Dec 22, 2011 ... carbonate, Fe-Mn oxide, organic matter and residual. All fractions were subsequently analyzed for lead ... smelting, fossil fuel combustion and various industrial activities. Many researchers (Chandra et ..... characterization, speciation and interraction studies of some pollutants in water and sediment.

  15. High Pressure Research on Materials

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 6. High Pressure Research on Materials - Production and Measurement of High Pressures in the Laboratory. P Ch Sahu N V Chandra Shekar. General Article Volume 12 Issue 6 June 2007 pp 10-23 ...

  16. Orbital apex syndrome caused by aspergilloma in an ...

    African Journals Online (AJOL)

    a disease of concern, as it is a leading cause of death in patients with haematological malignancies, those who are immuno compromised, and transplant .... sinus mycetoma with orbital involvement in a patient with. AIDS. Bildgebung 1995;62(3):199201. 7. Chandra P, Ahluwalia BK, Chugh TD. Primary orbital aspergilloma ...

  17. spectrophotometric methods for the microdetermination of ...

    African Journals Online (AJOL)

    Administrator

    Leonardo, P. (2009). Flow-injection spectrophotometric determination of tetracycline and doxycycline in pharmaceutical formulations using chloramine-T as oxidizing agent. Química. Nova, 32:1764-1769. Siva Chandra, Y.; Suryanarayana Rao, V. & Rama Murthy, P. S.. (1996). Determination of hostacycline and doxycycline ...

  18. Probes of Cosmic Star Formation History

    Indian Academy of Sciences (India)

    I summarize X-ray diagnostic studies of cosmic star formation history in terms of evolutionary schemes for X-ray binary evolution in normal galaxies with evolving star formation. Deep X-ray imaging studies by Chandra and XMM-Newton are now beginning to constrain both the X-ray luminosity evolution of galaxies and the ...

  19. Investigating the Nuclear Activity of Barred Spiral Galaxies: The Case of NGC 1672

    Science.gov (United States)

    2011-06-10

    source fluxes reliably, we have performed spectral fitting on each source using XSPEC v12. Detailed spectral fitting was performed on Chandra sources...count rate as observed in the ObsID 5932 data. The particle background spectra were then used as the “background” spectra within XSPEC , and the spectra

  20. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Volume 21 Issue 3-4 September-December 2000 pp 229-232 Session V – Vector Magnetic Fields, Prominences, CMEs & Flares. Analysis of the 9th November 1990 ... Extremely Energetic 4B/X17.2 Flare and Associated Phenomena · Wahab Uddin Ramesh Chandra ... 1 March 2015 pp 157-184. Solar Magnetic Flux Ropes.