The Restless Universe - Understanding X-Ray Astronomy in the Age of Chandra and Newton

Science.gov (United States)

Schlegel, Eric M.

2002-10-01

Carl Sagan once noted that there is only one generation that gets to see things for the first time. We are in the midst of such a time right now, standing on the threshold of discovery in the young and remarkable field of X-ray astronomy. In The Restless Universe , astronomer Eric Schlegel offers readers an informative survey of this cutting-edge science. Two major space observatories launched in the last few years--NASA's Chandra and the European Newton --are now orbiting the Earth, sending back a gold mine of data on the X-ray universe. Schlegel, who has worked on the Chandra project for seven years, describes the building and launching of this space-based X-ray observatory. But the book goes far beyond the story of Chandra . What Schlegel provides here is the background a nonscientist would need to grasp the present and follow the future of X-ray astronomy. He looks at the relatively brief history of the field, the hardware used to detect X-rays, the satellites--past, present, and future--that have been or will be flown to collect the data, the way astronomers interpret this data, and, perhaps most important, the insights we have already learned as well as speculations about what we may soon discover. And throughout the book, Schlegel conveys the excitement of looking at the universe from the perspective brought by these new observatories and the sharper view they deliver. Drawing on observations obtained from Chandra, Newton , and previous X-ray observatories, The Restless Universe gives a first look at an exciting field which significantly enriches our understanding of the universe.

Impacts of Chandra X-ray Observatory Public Communications and Engagement

Science.gov (United States)

Arcand, Kimberly K.; Watzke, Megan; Lestition, Kathleen; Edmonds, Peter

2015-01-01

The Chandra X-ray Observatory Center runs a multifaceted Public Communications & Engagement program encompassing press relations, public engagement, and education. Our goals include reaching a large and diverse audience of national and international scope, establishing direct connections and working relationships with the scientists whose research forms the basis for all products, creating peer-reviewed materials and activities that evolve from an integrated pipeline design and encourage users toward deeper engagement, and developing materials that target underserved audiences such as women, Spanish speakers, and the sight and hearing impaired. This talk will highlight some of the key features of our program, from the high quality curated digital presence to the cycle of research and evaluation that informs our practice at all points of the program creation. We will also discuss the main impacts of the program, from the tens of millions of participants reached through the establishment and sustainability of a network of science 'volunpeers.'

Chandra and RXTE studies of the X-ray/gamma-ray millisecond pulsar PSR J0218+4232

NARCIS (Netherlands)

Kuiper, L.; Hermsen, W.; Stappers, B.W.

2004-01-01

We report on high-resolution spatial and timing observations of the millisecond pulsar PSR J0218+4232 performed with the Chandra X-ray Observatory (CXO) and the Rossi X-ray Timing Explorer (RXTE). With these observations we were able to study: (a) the possible spatial extent at X-ray energies of the

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.

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.

CHANDRA X-RAY DETECTION OF THE ENIGMATIC FIELD STAR BP Psc

International Nuclear Information System (INIS)

Kastner, Joel H.; Montez, Rodolfo; Rodriguez, David; Zuckerman, B.; Perrin, Marshall D.; Grosso, Nicolas; Forveille, Thierry; Graham, James R.

2010-01-01

BP Psc is a remarkable emission-line field star that is orbited by a dusty disk and drives a parsec-scale system of jets. We report the detection by the Chandra X-ray Observatory of a weak X-ray point source coincident with the centroids of optical/IR and submillimeter continuum emission at BP Psc. As the star's photosphere is obscured throughout the visible and near-infrared, the Chandra X-ray source likely represents the first detection of BP Psc itself. The X-rays most likely originate with magnetic activity at BP Psc and hence can be attributed either to a stellar corona or to star-disk interactions. The log of the ratio of X-ray to bolometric luminosity, log(L X /L bol ), lies in the range -5.8 to -4.2. This is smaller than log(L X /L bol ) ratios typical of low-mass, pre-main sequence stars, but is well within the log(L X /L bol ) range observed for rapidly rotating (FK Com-type) G giant stars. Hence, the Chandra results favor an exotic model wherein the disk/jet system of BP Psc is the result of its very recently engulfing a companion star or a giant planet, as the primary star ascended the giant branch.

Chandra X-ray Center Science Data Systems Regression Testing of CIAO

Science.gov (United States)

Lee, N. P.; Karovska, M.; Galle, E. C.; Bonaventura, N. R.

2011-07-01

The Chandra Interactive Analysis of Observations (CIAO) is a software system developed for the analysis of Chandra X-ray Observatory observations. An important component of a successful CIAO release is the repeated testing of the tools across various platforms to ensure consistent and scientifically valid results. We describe the procedures of the scientific regression testing of CIAO and the enhancements made to the testing system to increase the efficiency of run time and result validation.

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).

Chandra and the VLT Jointly Investigate the Cosmic X-Ray Background

Science.gov (United States)

2001-03-01

Summary Important scientific advances often happen when complementary investigational techniques are brought together . In the present case, X-ray and optical/infrared observations with some of the world's foremost telescopes have provided the crucial information needed to solve a 40-year old cosmological riddle. Very detailed observations of a small field in the southern sky have recently been carried out, with the space-based NASA Chandra X-Ray Observatory as well as with several ground-based ESO telescopes, including the Very Large Telescope (VLT) at the Paranal Observatory (Chile). Together, they have provided the "deepest" combined view at X-ray and visual/infrared wavelengths ever obtained into the distant Universe. The concerted observational effort has already yielded significant scientific results. This is primarily due to the possibility to 'identify' most of the X-ray emitting objects detected by the Chandra X-ray Observatory on ground-based optical/infrared images and then to determine their nature and distance by means of detailed (spectral) observations with the VLT . In particular, there is now little doubt that the so-called 'X-ray background' , a seemingly diffuse short-wave radiation first detected in 1962, in fact originates in a vast number of powerful black holes residing in active nuclei of distant galaxies . Moreover, the present investigation has permitted to identify and study in some detail a prime example of a hitherto little known type of object, a distant, so-called 'Type II Quasar' , in which the central black hole is deeply embedded in surrounding gas and dust. These achievements are just the beginning of a most fruitful collaboration between "space" and "ground". It is yet another impressive demonstration of the rapid progress of modern astrophysics, due to the recent emergence of a new generation of extremely powerful instruments. PR Photo 09a/01 : Images of a small part of the Chandra Deep Field South , obtained with ESO telescopes

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

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

CHANDRA OBSERVATIONS OF SN 1987A: THE SOFT X-RAY LIGHT CURVE REVISITED

Energy Technology Data Exchange (ETDEWEB)

Helder, E. A.; Broos, P. S.; Burrows, D. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Dewey, D. [MIT Kavli Institute, Cambridge, MA 02139 (United States); Dwek, E. [Observational Cosmology Laboratory, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McCray, R. [JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309 (United States); Park, S. [Department of Physics, University of Texas at Arlington, Box 19059, Arlington, TX 76019 (United States); Racusin, J. L. [NASA, Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States); Zhekov, S. A. [Space Research and Technology Institute, Akad. G. Bonchev str., bl.1, Sofia 1113 (Bulgaria)

2013-02-10

We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by {approx}6 Multiplication-Sign 10{sup -13} erg s{sup -1} cm{sup -2} per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

Chandra Discovers X-ray Source at the Center of Our Galaxy

Science.gov (United States)

2000-01-01

Culminating 25 years of searching by astronomers, researchers at Massachusetts Institute of Technology say that a faint X-ray source, newly detected by NASA's Chandra X-ray Observatory, may be the long-sought X-ray emission from a known supermassive black hole at the center of our galaxy. Frederick K. Baganoff and colleagues from Pennsylvania State University, University Park, and the University of California, Los Angeles, will present their findings today in Atlanta at the 195th national meeting of the American Astronomical Society. Baganoff, lead scientist for the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer (ACIS) team's "Sagittarius A* and the Galactic Center" project and postdoctoral research associate at MIT, said that the precise positional coincidence between the new X-ray source and the radio position of a long-known source called Sagittarius A* "encourages us to believe that the two are the same." Sagittarius A* is a point-like, variable radio source at the center of our galaxy. It looks like a faint quasar and is believed to be powered by gaseous matter falling into a supermassive black hole with 2.6 million times the mass of our Sun. Chandra's remarkable detection of this X-ray source has placed astronomers within a couple of years of a coveted prize: measuring the spectrum of energy produced by Sagittarius A* to determine in detail how the supermassive black hole that powers it works. "The race to be the first to detect X-rays from Sagittarius A* is one of the hottest and longest-running in all of X-ray astronomy," Baganoff said. "Theorists are eager to hear the results of our observation so they can test their ideas." But now that an X-ray source close to Sagittarius A* has been found, it has taken researchers by surprise by being much fainter than expected. "There must be something unusual about the environment around this black hole that affects how it is fed and how the gravitational energy released from the infalling matter is

Initial Performance of the Attitude Control and Aspect Determination Subsystems on the Chandra Observatory

Science.gov (United States)

Cameron, R.; Aldcroft, T.; Podgorski, W. A.; Freeman, M. D.

2000-01-01

The aspect determination system of the Chandra X-ray Observatory plays a key role in realizing the full potential of Chandra's X-ray optics and detectors. We review the performance of the spacecraft hardware components and sub-systems, which provide information for both real time control of the attitude and attitude stability of the Chandra Observatory and also for more accurate post-facto attitude reconstruction. These flight components are comprised of the aspect camera (star tracker) and inertial reference units (gyros), plus the fiducial lights and fiducial transfer optics which provide an alignment null reference system for the science instruments and X-ray optics, together with associated thermal and structural components. Key performance measures will be presented for aspect camera focal plane data, gyro performance both during stable pointing and during maneuvers, alignment stability and mechanism repeatability.

Chandra Finds X-ray Star Bonanza in the Orion Nebula

Science.gov (United States)

2000-01-01

NASA's Chandra X-ray Observatory has resolved nearly a thousand faint X-ray-emitting stars in a single observation of young stars in the Orion Nebula. The discovery--the richest field of X-ray sources ever obtained in the history of X-ray astronomy--will be presented on Friday, January 14, at the 195th national meeting of the American Astronomical Society in Atlanta, Georgia. The Orion region is a dense congregation of about 2,000 very young stars formed during the past few million years. The discovery of such a wealth of X-ray stars in the closest massive star-forming region to Earth (only 1,500 light years away) is expected to have a profound impact on our understanding of star formation and evolution. "We've detected X-rays from so many fantastic objects, such as very young massive stars and stars so small that they may evolve into brown dwarfs," said Gordon Garmire, Evan Pugh Professor at Penn State University, University Park. "Chandra's superb angular resolution has resolved this dense cluster of stars with arcsecond accuracy and unsurpassed sensitivity." Garmire leads the team using Chandra's ACIS detector, the Advanced CCD Imaging Spectrometer, conceived and developed for NASA by Penn State University and the Massachusetts Institute of Technology. The brilliant Orion region has awed humankind for millennia. The most massive and brightest of these nascent stars are in the Orion Trapezium, which illuminates the Orion Nebula, also known as Messier 42. The Trapezium and its luminous gas can be seen with the unaided eye in the winter sky in the "sword" of the Orion constellation. Young stars, such as those found in Orion, are known to be much brighter in X-rays than middle-aged stars such as the Sun. The elevated X-ray emission is thought to arise from violent flares in strong magnetic fields near the surfaces of young stars. The Sun itself was probably thousands of times brighter in X-rays during its first few million years. Although the enhanced magnetic

The Cosmic History of Black Hole Accretion from Chandra X-ray Stacking

Science.gov (United States)

Treister, Ezequiel; Urry, C.; Schawinski, K.; Lee, N.; Natarajan, P.; Volonteri, M.; Sanders, D. B.

2012-05-01

In order to fully understand galaxy formation we need to know when in the cosmic history are black holes growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. We take advantage of the rich multi-wavelength data available in the Chandra Deep Field South (CDF-S), including the 4 Msec Chandra observations (the deepest X-ray data to date), in order to measure the amount of black hole accretion as a function of cosmic history, from z 0 to z 6. We obtain stacked rest-frame X-ray spectra for samples of galaxies binned in terms of their IR luminosity, stellar mass and other galaxy properties. We find that the AGN fraction and their typical luminosities, and thus black hole accretion rates, increase with IR luminosity and stellar mass. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations. We find evidence for a strong connection between significant black hole growth events and major galaxy mergers from z 0 to z 3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. E.T. and K.S. gratefully acknowledges the support provided by NASA through Chandra Postdoctoral Fellowship Award Numbers PF8-90055 and PF9-00069, respectively issued by the Chandra X-ray Observatory Center. E.T. also thanks support by NASA through Chandra Award SP1-12005X Center of Excellence in Astrophysics and Associated Technologies (PFB 06). C. M. Urry acknowledges support from NSF Grants AST-0407295, AST-0449678, AST-0807570, and Yale University.

A Chandra High-Resolution X-ray Image of Centaurus A.

Science.gov (United States)

Kraft; Forman; Jones; Kenter; Murray; Aldcroft; Elvis; Evans; Fabbiano; Isobe; Jerius; Karovska; Kim; Prestwich; Primini; Schwartz; Schreier; Vikhlinin

2000-03-01

We present first results from a Chandra X-Ray Observatory observation of the radio galaxy Centaurus A with the High-Resolution Camera. All previously reported major sources of X-ray emission including the bright nucleus, the jet, individual point sources, and diffuse emission are resolved or detected. The spatial resolution of this observation is better than 1&arcsec; in the center of the field of view and allows us to resolve X-ray features of this galaxy not previously seen. In particular, we resolve individual knots of emission in the inner jet and diffuse emission between the knots. All of the knots are diffuse at the 1&arcsec; level, and several exhibit complex spatial structure. We find the nucleus to be extended by a few tenths of an arcsecond. Our image also suggests the presence of an X-ray counterjet. Weak X-ray emission from the southwest radio lobe is also seen, and we detect 63 pointlike galactic sources (probably X-ray binaries and supernova remnants) above a luminosity limit of approximately 1.7x1037 ergs s-1.

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.

Chandra X-ray Data Analysis in Educational Environments

Science.gov (United States)

Matilsky, T.; Etkina, E.; Lestition, K.; Mandel, E.; Joye, W.

2004-12-01

Recent progress in both software and remote connectivity capabilities have made it possible for authentic data analysis tasks to be presented in a wide range of educational venues. No longer are precollege teachers and students, and interested members of the public limited by their lack of access to the scientific workstations and UNIX-based imaging and analytical software used by the research community. Through a suite of programs that couples a simplified graphical user interface using the "DS9" imaging software with a "virtual observatory" capability that processes the analytical algorithms used by X-ray astronomers, we can access archived Chandra observations and generate images, as well as light curves, energy spectra, power spectra and other common examples of science tasks. The system connects to a remote UNIX server, but the user may be sited on a PC or Mac platform. Furthermore, the use of VNC (a remote desktop display environment) allows a teacher to view, comment on and debug any analysis task in real time, from anywhere in the world, and across any computer platform. This makes these programs especially useful in distance learning settings. We have developed, tested and used these capabilities in a wide variety of educational arenas, from 4 week intensive courses in X-ray astronomy research techniques for precollege students and teachers, to one day teacher enrichment workshops, to modules of classroom activities suitable for precollege grade levels, using a variety of cosmic X-ray sources. Examples using archived Chandra observations will be presented demonstrating the flexibility and usefulness of these resources.

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

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.

THE X-RAY FLUX DISTRIBUTION OF SAGITTARIUS A* AS SEEN BY CHANDRA

International Nuclear Information System (INIS)

Neilsen, J.; Anton Pannekoek, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands))" data-affiliation=" (Astronomical Institute, Anton Pannekoek, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands))" >Markoff, S.; Nowak, M. A.; Baganoff, F. K.; Dexter, J.; Witzel, G.; Barrière, N.; Li, Y.; Degenaar, N.; Fragile, P. C.; Gammie, C.; Goldwurm, A.; Grosso, N.; Haggard, D.

2015-01-01

We present a statistical analysis of the X-ray flux distribution of Sgr A* from the Chandra X-Ray Observatory's 3 Ms Sgr A* X-ray Visionary Project in 2012. Our analysis indicates that the observed X-ray flux distribution can be decomposed into a steady quiescent component, represented by a Poisson process with rate Q = (5.24 ± 0.08) × 10 –3  counts s –1 , and a variable component, represented by a power law process (dN/dF∝F –ξ , ξ=1.92 −0.02 +0.03 ). This slope matches our recently reported distribution of flare luminosities. The variability may also be described by a log-normal process with a median unabsorbed 2-8 keV flux of 1.8 −0.6 +0.8 ×10 −14  erg s –1  cm –2 and a shape parameter σ = 2.4 ± 0.2, but the power law provides a superior description of the data. In this decomposition of the flux distribution, all of the intrinsic X-ray variability of Sgr A* (spanning at least three orders of magnitude in flux) can be attributed to flaring activity, likely in the inner accretion flow. We confirm that at the faint end, the variable component contributes ∼10% of the apparent quiescent flux, as previously indicated by our statistical analysis of X-ray flares in these Chandra observations. Our flux distribution provides a new and important observational constraint on theoretical models of Sgr A*, and we use simple radiation models to explore the extent to which a statistical comparison of the X-ray and infrared can provide insights into the physics of the X-ray emission mechanism

THE X-RAY FLUX DISTRIBUTION OF SAGITTARIUS A* AS SEEN BY CHANDRA

Energy Technology Data Exchange (ETDEWEB)

Neilsen, J. [Department of Astronomy, Boston University, Boston, MA 02215 (United States); Markoff, S. [Astronomical Institute, " Anton Pannekoek," University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Nowak, M. A.; Baganoff, F. K. [MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Dexter, J. [Department of Astronomy, Hearst Field Annex, University of California, Berkeley, CA 94720-3411 (United States); Witzel, G. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Barrière, N. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Li, Y. [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China); Degenaar, N. [Institute of Astronomy, University of Cambridge, Cambridge, CB3 OHA (United Kingdom); Fragile, P. C. [Department of Physics and Astronomy, College of Charleston, Charleston, SC 29424 (United States); Gammie, C. [Department of Astronomy, University of Illinois Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Goldwurm, A. [AstroParticule et Cosmologie (APC), Université Paris 7 Denis Diderot, F-75205 Paris cedex 13 (France); Grosso, N. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Haggard, D., E-mail: jneilsen@space.mit.edu [Department of Physics and Astronomy, AC# 2244, Amherst College, Amherst, MA 01002 (United States)

2015-02-01

We present a statistical analysis of the X-ray flux distribution of Sgr A* from the Chandra X-Ray Observatory's 3 Ms Sgr A* X-ray Visionary Project in 2012. Our analysis indicates that the observed X-ray flux distribution can be decomposed into a steady quiescent component, represented by a Poisson process with rate Q = (5.24 ± 0.08) × 10{sup –3} counts s{sup –1}, and a variable component, represented by a power law process (dN/dF∝F {sup –ξ}, ξ=1.92{sub −0.02}{sup +0.03}). This slope matches our recently reported distribution of flare luminosities. The variability may also be described by a log-normal process with a median unabsorbed 2-8 keV flux of 1.8{sub −0.6}{sup +0.8}×10{sup −14} erg s{sup –1} cm{sup –2} and a shape parameter σ = 2.4 ± 0.2, but the power law provides a superior description of the data. In this decomposition of the flux distribution, all of the intrinsic X-ray variability of Sgr A* (spanning at least three orders of magnitude in flux) can be attributed to flaring activity, likely in the inner accretion flow. We confirm that at the faint end, the variable component contributes ∼10% of the apparent quiescent flux, as previously indicated by our statistical analysis of X-ray flares in these Chandra observations. Our flux distribution provides a new and important observational constraint on theoretical models of Sgr A*, and we use simple radiation models to explore the extent to which a statistical comparison of the X-ray and infrared can provide insights into the physics of the X-ray emission mechanism.

Most powerful X-ray telescope marks third anniversary

Science.gov (United States)

2002-08-01

A black hole gobbles up matter in our own Milky Way Galaxy. A hot spot of X-rays pulsates from near Jupiter's poles. An intergalactic web of hot gas, hidden from view since the time galaxies formed, is finally revealed. These scenarios sound like science fiction - but to those familiar with the latest developments in X-ray astronomy, they are just a few of the real-life discoveries made by NASA's Chandra X-ray Observatory during its third year of operation. "Within the last year, Chandra has revealed another series of never-before-seen phenomena in our galaxy and beyond," said Chandra project scientist Dr. Martin Weisskopf of NASA's Marshall Space Flight Center in Huntsville, Ala. "When you combine recent discoveries with the secrets revealed during the observatory's first two years in orbit, it's amazing how much Chandra has told us about the universe in a relatively short period of time." One such discovery was an unprecedented view of a supermassive black hole devouring material in the Milky Way Galaxy - a spectacle witnessed for the first time when Chandra observed a rapid X-ray flare emitted from the direction of the black hole residing at our galaxy's center. In a just few minutes, Sagittarius A, a source of radio emission believed to be associated with the black hole, became 45 times brighter in X-rays, before declining to pre-flare levels a few hours later, offering astronomers a never-before-seen view of the energetic processes surrounding this supermassive black hole. "When we launched the Chandra Observatory, we attempted to explain its amazing capabilities in Earthly terms, such as the fact it can 'see' so well, it's like someone reading the letters of a stop sign 12 miles away," said Chandra Program Manager Tony Lavoie of the Marshall Center. "But now that the observatory has been in orbit for three years, we have unearthly proof of the technological marvel Chandra really is. Not only has it continued to operate smoothly and efficiently, it has

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.

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

Adaptive grazing incidence optics for the next generation of x-ray observatories

Science.gov (United States)

Lillie, C.; Pearson, D.; Plinta, A.; Metro, B.; Lintz, E.; Shropshire, D.; Danner, R.

2010-09-01

Advances in X-ray astronomy require high spatial resolution and large collecting area. Unfortunately, X-ray telescopes with grazing incidence mirrors require hundreds of concentric mirror pairs to obtain the necessary collecting area, and these mirrors must be thin shells packed tightly together... They must also be light enough to be placed in orbit with existing launch vehicles, and able to be fabricated by the thousands for an affordable cost. The current state of the art in X-ray observatories is represented by NASA's Chandra X-ray observatory with 0.5 arc-second resolution, but only 400 cm2 of collecting area, and by ESA's XMM-Newton observatory with 4,300 cm2 of collecting area but only 15 arc-second resolution. The joint NASA/ESA/JAXA International X-ray Observatory (IXO), with {15,000 cm2 of collecting area and 5 arc-second resolution which is currently in the early study phase, is pushing the limits of passive mirror technology. The Generation-X mission is one of the Advanced Strategic Mission Concepts that NASA is considering for development in the post-2020 period. As currently conceived, Gen-X would be a follow-on to IXO with a collecting area >= 50 m2, a 60-m focal length and 0.1 arc-second spatial resolution. Gen-X would be launched in {2030 with a heavy lift Launch Vehicle to an L2 orbit. Active figure control will be necessary to meet the challenging requirements of the Gen-X optics. In this paper we present our adaptive grazing incidence mirror design and the results from laboratory tests of a prototype mirror.

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

Optics Developments for X-Ray Astronomy

Science.gov (United States)

Ramsey, Brian

2014-01-01

X-ray optics has revolutionized x-ray astronomy. The degree of background suppression that these afford, have led to a tremendous increase in sensitivity. The current Chandra observatory has the same collecting area (approx. 10(exp 3)sq cm) as the non-imaging UHURU observatory, the first x-ray observatory which launched in 1970, but has 5 orders of magnitude more sensitivity due to its focusing optics. In addition, its 0.5 arcsec angular resolution has revealed a wealth of structure in many cosmic x-ray sources. The Chandra observatory achieved its resolution by using relatively thick pieces of Zerodur glass, which were meticulously figured and polished to form the four-shell nested array. The resulting optical assembly weighed around 1600 kg, and cost approximately $0.5B. The challenge for future x-ray astronomy missions is to greatly increase the collecting area (by one or more orders of magnitude) while maintaining high angular resolution, and all within realistic mass and budget constraints. A review of the current status of US optics for x-ray astronomy will be provided along with the challenges for future developments.

Second Chandra Instrument Activated August 28

Science.gov (United States)

1999-08-01

Cambridge, MA--NASA's Chandra X-ray Observatory opened a new era in astronomy Saturday, August 28, by making the most precise measurements ever recorded of the energy output from the 10 million degree corona of a star. Last weekend's observations came after the successful activation of an instrument developed by MIT that will allow a one-thousand-fold improvement in the capability to measure X-ray spectra from space. The new measurements, made with the High Energy Transmission Grating Spectrometer, join spectacular images taken last week by Chandra of the aftermath of a gigantic stellar explosion. The spectrometer is one of four key instruments aboard Chandra, and the second to be activated. The others will be turned on over the next two weeks. The spectrometer activated yesterday spreads the X-rays from Chandra's mirrors into a spectrum, much as a prism spreads light into its colors. The spectrum then can be read by Chandra's imaging detectors like a kind of cosmic bar code from which scientists can deduce the chemical composition and temperature of the corona. A corona is a region of hot gas and magnetic loops that extend hundreds of thousands of miles above the star's visible surface and is best studied with X-rays. "The success of the new spectrometer is definitely a major milestone for modern astronomy," said MIT Professor Claude R. Canizares, principal investigator for the instrument and associate director of the Chandra X-ray Observatory Center (CXC). "Within the first hour we had obtained the best X-ray spectrum ever recorded for a celestial source. We can already see unexpected features that will teach us new things about stars and about matter at high temperatures." The spectrometer measured X-rays from the star Capella, which is 40 light years away in the constellation Auriga. Capella is actually two stars orbiting one another and possibly interacting in ways that pump extra heat into the corona, which appears more active than that of the Sun. How a star

X-ray Optics Development at MSFC

Science.gov (United States)

Sharma, Dharma P.

2017-01-01

Development of high resolution focusing telescopes has led to a tremendous leap in sensitivity, revolutionizing observational X-ray astronomy. High sensitivity and high spatial resolution X-ray observations have been possible due to use of grazing incidence optics (paraboloid/hyperboloid) coupled with high spatial resolution and high efficiency detectors/imagers. The best X-ray telescope flown so far is mounted onboard Chandra observatory launched on July 23,1999. The telescope has a spatial resolution of 0.5 arc seconds with compatible imaging instruments in the energy range of 0.1 to 10 keV. The Chandra observatory has been responsible for a large number of discoveries and has provided X-ray insights on a large number of celestial objects including stars, supernova remnants, pulsars, magnetars, black holes, active galactic nuclei, galaxies, clusters and our own solar system.

Early Chandra X-ray Observations of Eta Carinae

OpenAIRE

Seward, F. D.; Butt, Y. M.; Karovska, M.; Schlegel, A. Prestwich. E. M.; Corcoran, M.

2001-01-01

Sub-arcsecond resolution Chandra observations of Eta Carinae reveal a 40 arcsec X 70 arcsec ring or partial shell of X-ray emission surrounding an unresolved, bright, central source. The spectrum of the central source is strongly absorbed and can be fit with a high-temperature thermal continuum and emission lines. The surrounding shell is well outside the optical/IR bipolar nebula and is coincident with the Outer Shell of Eta Carinae. The X-ray spectrum of the Shell is much softer than that o...

NASA X-Ray Observatory Completes Tests Under Harsh Simulated Space Conditions

Science.gov (United States)

1998-07-01

, the telescope's mirrors were built by Raytheon Optical Systems Inc., Danbury, Conn. The mirrors were coated by Optical Coating Laboratory, Inc., Santa Rosa, Calif., and assembled by EastmanKodak Co., Rochester, N.Y. The Advanced X-ray Astrophysics Facility Charge-Coupled Device Imaging Spectrometer was developed by Pennsylvania State University, University Park, Pa., and the Massachusetts Institute of Technology (MIT), Cambridge. One diffraction grating was developed by MIT, the other by the Space Research Organization Netherlands, Utrecht, Netherlands, in collaboration with the Max Planck Institute, Garching, Germany. The High Resolution Camera was built by the Smithsonian Astrophysical Observatory. Ball Aerospace & Technologies Corporation of Boulder, Colo., developed the aspect camera and the Science Instrument Module. Note to editors: Digital images to accompany this release are available via the World Wide Web at the following URL: http://chandra.harvard.edu/press/images.html

Initial Performance of the Aspect System on the Chandra Observatory: Post-Facto Aspect Reconstruction

Science.gov (United States)

Aldcroft, T.; Karovska, M.; Cresitello-Dittmar, M.; Cameron, R.

2000-01-01

The aspect system of the Chandra Observatory plays a key role in realizing the full potential of Chandra's x-ray optics and detectors. To achieve the highest spatial and spectral resolution (for grating observations), an accurate post-facto time history of the spacecraft attitude and internal alignment is needed. The CXC has developed a suite of tools which process sensor data from the aspect camera assembly and gyroscopes, and produce the spacecraft aspect solution. In this poster, the design of the aspect pipeline software is briefly described, followed by details of aspect system performance during the first eight months of flight. The two key metrics of aspect performance are: image reconstruction accuracy, which measures the x-ray image blurring introduced by aspect; and celestial location, which is the accuracy of detected source positions in absolute sky coordinates.

Chandra X-ray Observations of Jovian Low-latitude Emissions: Morphological, Temporal, and Spectral Characteristics

Science.gov (United States)

Bhardwaj, Anil; Elsner, Ronald F.; Gladstone, G. Randall; Cravens, Thomas E.; Waiate J. Hunter, Jr.; Branduardi-Raymont, Graziella; Ford, Peter

2004-01-01

Chandra observed X-rays from Jupiter during 24-26 February 2003 for about 40 hours with the ACIS-S and HRC-I instruments. The analysis of Jovian low-latitude "disk" Xray emissions are presented and compared with the high-latitude "auroral" emissions. We report the first Chandra ACIS-S measured X-ray spectrum (0.3-2 keV) of Jupiter's low-latitude disk The disk X-ray emission is harder and extends to higher energies than the auroral spectrum. The temporal variation in the Jovian disk X-rays is on an average consistent with those in the solar X-rays observed by GOES, and TIMED/SSE. Contrary to the auroral X-rays, the disk emissions are uniformly distributed over Jupiter; no indication of longitudinal dependence or correlation with surface magneh field strength is visible. Also, unlike the approx. 40 +/- 20 min periodic oscillations seen in the auroral X-ray emissions, the disk emissions do not show any periodic oscillations. The disk spectrum seems to be consistent with resonant and fluorescent scattering of solar X-rays by the Jovian upper atmosphere. Jupiter's disk is found to be about 50% dimmer in soft X-rays in February 2003 compared that in December 2000, which is consistent with the decrease in solar activity. No evidence of lightning-induced X-rays is seen in the Chandra X-ray data. The Jovian disk spectra observed with Chandra-ACIS is stronger than that observed with XMM-Newton two months later during April 28-29, 2003. The XMM-Newton Xray image of Jupiter shows evidence of limb darkening on the anti-sunward side as seen from Earth, as well as an asymmetry with respect to the subsolar point: suggesting a solar driven process.

X-Ray Optics: Past, Present, and Future

Science.gov (United States)

Zhang, William W.

2010-01-01

X-ray astronomy started with a small collimated proportional counter atop a rocket in the early 1960s. It was immediately recognized that focusing X-ray optics would drastically improve both source location accuracy and source detection sensitivity. In the past 5 decades, X-ray astronomy has made significant strides in achieving better angular resolution, large photon collection area, and better spectral and timing resolutions, culminating in the three currently operating X-ray observatories: Chandra, XMM/Newton, and Suzaku. In this talk I will give a brief history of X-ray optics, concentrating on the characteristics of the optics of these three observatories. Then I will discuss current X-ray mirror technologies being developed in several institutions. I will end with a discussion of the optics for the International X-ray Observatory that I have been developing at Goddard Space Flight Center.

Deepest X-Rays Ever Reveal universe Teeming With Black Holes

Science.gov (United States)

2001-03-01

For the first time, astronomers believe they have proof black holes of all sizes once ruled the universe. NASA's Chandra X-ray Observatory provided the deepest X-ray images ever recorded, and those pictures deliver a novel look at the past 12 billion years of black holes. Two independent teams of astronomers today presented images that contain the faintest X-ray sources ever detected, which include an abundance of active super massive black holes. "The Chandra data show us that giant black holes were much more active in the past than at present," said Riccardo Giacconi, of Johns Hopkins University and Associated Universities, Inc., Washington, DC. The exposure is known as "Chandra Deep Field South" since it is located in the Southern Hemisphere constellation of Fornax. "In this million-second image, we also detect relatively faint X-ray emission from galaxies, groups, and clusters of galaxies". The images, known as Chandra Deep Fields, were obtained during many long exposures over the course of more than a year. Data from the Chandra Deep Field South will be placed in a public archive for scientists beginning today. "For the first time, we are able to use X-rays to look back to a time when normal galaxies were several billion years younger," said Ann Hornschemeier, Pennsylvania State University, University Park. The group’s 500,000-second exposure included the Hubble Deep Field North, allowing scientists the opportunity to combine the power of Chandra and the Hubble Space Telescope, two of NASA's Great Observatories. The Penn State team recently acquired an additional 500,000 seconds of data, creating another one-million-second Chandra Deep Field, located in the constellation of Ursa Major. Chandra Deep Field North/Hubble Deep Field North Press Image and Caption The images are called Chandra Deep Fields because they are comparable to the famous Hubble Deep Field in being able to see further and fainter objects than any image of the universe taken at X-ray

Compton Gamma-Ray Observatory

Science.gov (United States)

1991-01-01

This photograph shows the Compton Gamma-Ray Observatory (GRO) being deployed by the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-37 mission in April 1991. The GRO reentered Earth atmosphere and ended its successful mission in June 2000. For nearly 9 years, the GRO Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center (MSFC), kept an unblinking watch on the universe to alert scientists to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of stars, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in the BATSE science program.

Chandra X-ray Time-Domain Study of Alpha Centauri AB, Procyon, and their Environs

Science.gov (United States)

Ayres, Thomas R.

2018-06-01

For more than a decade, Chandra X-ray Observatory has been monitoring the central AB binary (G2V+K1V) of the α Centauri triple system with semi-annual pointings, using the High-Resolution Camera. This study has been extended in recent years to the mid-F subgiant, Procyon. The main objective is to follow the coronal (T~1MK) activity variations of the three stars, analogous to the Sun's 11-year sunspot cycle. Tentative periods of 20 yr and 8 yr have been deduced for α Cen A and B, respectively; but so far Procyon has shown only a slow, very modest decline in count rate, which could well reflect a slight instrumental degradation rather than intrinsic behavior. The negligible high-energy variability of Procyon sits in stark contrast to the dramatic factor of several to ten changes in the X-ray luminosities of α Cen AB and the Sun over their respective cycles. Further, although sunlike α Cen A has been observed by successive generations of X-ray observatories for nearly four decades, albeit sporadically, there are key gaps in the coverage that affect the determination of the cycle period. In fact, the most recent pointings suggest a downturn in A's count rate that might be signaling a shorter, more solar-like cycle following a delayed minimum in the 2005--2010 time frame (perhaps an exaggerated version of the extended solar minimum between recent Cycles 23 and 24). Beyond the coronal cycles of the three stars, the sequence of periodic X-ray images represents a unique time-domain history concerning steady as well as variable sources in the two 30'x30' fields. The most conspicuous of the variable objects -- in the α Cen field -- will be described here.

Lunar Prospecting With Chandra

Science.gov (United States)

2003-09-01

Observations of the bright side of the Moon with NASA's Chandra X-ray Observatory have detected oxygen, magnesium, aluminum and silicon over a large area of the lunar surface. The abundance and distribution of those elements will help to determine how the Moon was formed. "We see X-rays from these elements directly, independent of assumptions about the mineralogy and other complications," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., at a press conference at the "Four Years with Chandra" symposium in Huntsville, Alabama. "We have Moon samples from the six widely-space Apollo landing sites, but remote sensing with Chandra can cover a much wider area," continued Drake. "It's the next best thing to being there, and it's very fast and cost-effective." The lunar X-rays are caused by fluorescence, a process similar to the way that light is produced in fluorescent lamps. Solar X-rays bombard the surface of the Moon, knock electrons out of the inner parts of the atoms, putting them in a highly unstable state. Almost immediately, other electrons rush to fill the gaps, and in the process convert their energy into the fluorescent X-rays seen by Chandra. According to the currently popular "giant impact" theory for the formation of the Moon, a body about the size of Mars collided with the Earth about 4.5 billion years ago. This impact flung molten debris from the mantle of both the Earth and the impactor into orbit around the Earth. Over the course of tens of millions of years, the debris stuck together to form the Moon. By measuring the amounts of aluminum and other elements over a wide area of the Moon and comparing them to the Earth's mantle, Drake and his colleagues plan to help test the giant impact hypothesis. "One early result," quipped Drake, "is that there is no evidence for large amounts of calcium, so cheese is not a major constituent of the Moon." Illustration of Earth's Geocorona Illustration of Earth's Geocorona The same

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.

PSR J2124-3358: A Bow Shock Nebula with an X-ray Tail

Science.gov (United States)

Chatterjee, S.; Gaensler, B. M.; Vigelius, M.; Cordes, J. M.; Arzoumanian, Z.; Stappers, B.; Ghavamian, P.; Melatos, A.

2005-12-01

As neutron stars move supersonically through the interstellar medium, their relativistic winds are confined by the ram pressure of the interstellar medium. The outer shocked layers may emit in Hα , producing a visible bow shock nebula, while the confined relativistic wind may produce radio or X-ray emission. The Hα bow shock nebula powered by the recycled pulsar J2124-3358 is asymmetric about the velocity vector and shows a marked kink. In recent observations with the Chandra X-ray Observatory, we have detected a long, curved X-ray tail associated with the pulsar. The tail is not aligned with the pulsar velocity, but is confined within the optical bow shock. The X-ray spectrum of the tail is well-fit by a power law, consistent with synchrotron emission from the wind termination shock and the post-shock flow. The presence of Hα and X-ray emission allows us to trace both the external ambient medium and the confined wind. In magnetohydrodynamic simulations, we verify that a bulk flow and non-uniformities in the ambient medium can produce the observed shape of the nebula, possibly in combination with an anisotropic pulsar wind. Support for this work was provided by the National Aeronautics and Space Administration through Chandra Award Number GO5-6075X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060.

CHANDRA, KECK, AND VLA OBSERVATIONS OF THE CRAB NEBULA DURING THE 2011-APRIL GAMMA-RAY FLARE

Energy Technology Data Exchange (ETDEWEB)

Weisskopf, Martin C.; Tennant, Allyn F.; O' Dell, Stephen L. [NASA Marshall Space Flight Center, Astrophysics Office (ZP12), Huntsville, AL 35812 (United States); Arons, Jonathan [Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); Blandford, Roger; Funk, Stefan; Romani, Roger W. [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); Buehler, Rolf [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Caraveo, Patrizia; De Luca, Andrea [INAF-IASF Milano, via E. Bassini 15, I-20133 Milano (Italy); Cheung, Chi C. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Costa, Enrico [INFN Roma Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Ferrigno, Carlo [ISDC, Data Center for Astrophysics of the University of Geneva, chemin d' cogia 16, CH-1290 Versoix (Switzerland); Fu, Hai [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Habermehl, Moritz; Horns, Dieter [Institut fuer Experimentalphysik, Universitaet Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany); Linford, Justin D. [Department of Physics and Astronomy, University of New Mexico, MSC07 4220, Albuquerque, NM 87131-0001 (United States); Lobanov, Andrei [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Max, Claire [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Mignani, Roberto [Mullard Space Science Laboratory, University College London, Holmbury St. Mary Dorking, Surrey RH5 6NT (United Kingdom); and others

2013-03-01

We present results from our analysis of Chandra X-Ray Observatory, W. M. Keck Observatory, and Karl G. Jansky Very Large Array (VLA) images of the Crab Nebula that were contemporaneous with the {gamma}-ray flare of 2011 April. Despite hints in the X-ray data, we find no evidence for statistically significant variations that pinpoint the specific location of the flares within the Nebula. The Keck observations extend this conclusion to the 'inner knot', i.e., the feature within an arcsecond of the pulsar. The VLA observations support this conclusion. We also discuss theoretical implications of the {gamma}-ray flares and suggest that the most dramatic {gamma}-ray flares are due to radiation-reaction-limited synchrotron emission associated with sudden, dissipative changes in the current system sustained by the central pulsar.

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

Energy Technology Data Exchange (ETDEWEB)

Hong, JaeSub; Antoniou, Vallia; Zezas, Andreas; Drake, Jeremy J.; Plucinsky, Paul P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Haberl, Frank [Max-Planck-Institut für extraterrestrische Physik, Giessenbach straße, D-85748 Garching (Germany); Sasaki, Manami [Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstrasse 7, 96049 Bamberg (Germany); Laycock, Silas, E-mail: jaesub@head.cfa.harvard.edu [Department of Physics, University of Massachusetts Lowell, MA 01854 (United States)

2017-09-20

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 deg{sup 2} 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 {sub X} ) of the pulsars ranges from 10{sup 34} to 10{sup 37} erg s{sup −1} at 60 kpc. All of the Chandra sources with L {sub X} ≳ 4 × 10{sup 35} erg s{sup −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).

Chandra Images Provide New Vision of Cosmic Explosions

Science.gov (United States)

1999-09-01

Images from NASA's Chandra X-ray Observatory released today reveal previously unobserved features in the remnants of three different supernova explosions. Two of the remnants G21.5-0.9 and PSR 0540-69 show dramatic details of the prodigious production of energetic particles by a rapidly rotating, highly magnetized neutron star, as well as the enormous shell structures produced by the explosions. The image of the third remnant, E0102-72, reveals puzzling spoke-like structures in its interior. G21.5-0.9, in the constellation of Scutum, is about 16,000 light years (1 light year = 6 trillion miles) from Earth. Chandra's image shows a bright nebula surrounded by a much larger diffuse cloud. Inside the inner nebula is a bright central source that is thought to be a rapidly rotating highly magnetized neutron star. A rotating neutron star acts like a powerful generator, creating intense electric voltages that accelerate electrons to speeds close to the speed of light. The total output of this generator is greater than a thousand suns. The fluffy appearance of the central nebula is thought to be due to magnetic field lines which constrain the motions of the high-energy electrons. "It's a remarkable image," said Dr. Patrick Slane of the Harvard-Smithsonian Center for Astrophysics. "Neither the inner core nor the outer shell has ever been seen before." "It is as though we have a set of Russian dolls, with structures embedded within structures," said Professor Gordon Garmire of Penn State University, and principal investigator of the Advanced CCD Imaging Spectrometer, the X-ray camera that was used to make two of the images. NASA's project scientist, Dr. Martin Weisskopf of the Marshall Space Flight Center said, "Chandra's capability to provide surprises and insights continues." PSR 0540-69 PSR 0540-69 The existence of a rotating neutron star, or pulsar, in the center of G21.5-0.9 is inferred from the appearance of the nebula and the energy distribution of X-rays and radio

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.

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.

X-ray optics developments at ESA

DEFF Research Database (Denmark)

Bavdaz, M.; Wille, E.; Wallace, K.

2013-01-01

Future high energy astrophysics missions will require high performance novel X-ray optics to explore the Universe beyond the limits of the currently operating Chandra and Newton observatories. Innovative optics technologies are therefore being developed and matured by the European Space Agency (ESA......) in collaboration with research institutions and industry, enabling leading-edge future science missions. Silicon Pore Optics (SPO) [1 to 21] and Slumped Glass Optics (SGO) [22 to 29] are lightweight high performance X-ray optics technologies being developed in Europe, driven by applications in observatory class...... reflective coatings [30 to 35]. In addition, the progress with the X-ray test facilities and associated beam-lines is discussed [36]. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only....

Planetary Protection: X-ray Super-Flares Aid Formation of "Solar Systems"

Science.gov (United States)

2005-05-01

New results from NASA's Chandra X-ray Observatory imply that X-ray super-flares torched the young Solar System. Such flares likely affected the planet-forming disk around the early Sun, and may have enhanced the survival chances of Earth. By focusing on the Orion Nebula almost continuously for 13 days, a team of scientists used Chandra to obtain the deepest X-ray observation ever taken of this or any star cluster. The Orion Nebula is the nearest rich stellar nursery, located just 1,500 light years away. These data provide an unparalleled view of 1400 young stars, 30 of which are prototypes of the early Sun. The scientists discovered that these young suns erupt in enormous flares that dwarf - in energy, size, and frequency -- anything seen from the Sun today. Illustration of Large Flares Illustration of Large Flares "We don't have a time machine to see how the young Sun behaved, but the next best thing is to observe Sun-like stars in Orion," said Scott Wolk of Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "We are getting a unique look at stars between one and 10 million years old - a time when planets form." A key result is that the more violent stars produce flares that are a hundred times as energetic as the more docile ones. This difference may specifically affect the fate of planets that are relatively small and rocky, like the Earth. "Big X-ray flares could lead to planetary systems like ours where Earth is a safe distance from the Sun," said Eric Feigelson of Penn State University in University Park, and principal investigator for the international Chandra Orion Ultradeep Project. "Stars with smaller flares, on the other hand, might end up with Earth-like planets plummeting into the star." Animation of X-ray Flares from a Young Sun Animation of X-ray Flares from a "Young Sun" According to recent theoretical work, X-ray flares can create turbulence when they strike planet-forming disks, and this affects the position of rocky planets as they

Chandra Independently Determines Hubble Constant

Science.gov (United States)

2006-08-01

A critically important number that specifies the expansion rate of the Universe, the so-called Hubble constant, has been independently determined using NASA's Chandra X-ray Observatory. This new value matches recent measurements using other methods and extends their validity to greater distances, thus allowing astronomers to probe earlier epochs in the evolution of the Universe. "The reason this result is so significant is that we need the Hubble constant to tell us the size of the Universe, its age, and how much matter it contains," said Max Bonamente from the University of Alabama in Huntsville and NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., lead author on the paper describing the results. "Astronomers absolutely need to trust this number because we use it for countless calculations." Illustration of Sunyaev-Zeldovich Effect Illustration of Sunyaev-Zeldovich Effect The Hubble constant is calculated by measuring the speed at which objects are moving away from us and dividing by their distance. Most of the previous attempts to determine the Hubble constant have involved using a multi-step, or distance ladder, approach in which the distance to nearby galaxies is used as the basis for determining greater distances. The most common approach has been to use a well-studied type of pulsating star known as a Cepheid variable, in conjunction with more distant supernovae to trace distances across the Universe. Scientists using this method and observations from the Hubble Space Telescope were able to measure the Hubble constant to within 10%. However, only independent checks would give them the confidence they desired, considering that much of our understanding of the Universe hangs in the balance. Chandra X-ray Image of MACS J1149.5+223 Chandra X-ray Image of MACS J1149.5+223 By combining X-ray data from Chandra with radio observations of galaxy clusters, the team determined the distances to 38 galaxy clusters ranging from 1.4 billion to 9.3 billion

Adjustable Grazing-Incidence X-Ray Optics

Science.gov (United States)

O'Dell, Stephen L.; Reid, Paul B.

2015-01-01

With its unique subarcsecond imaging performance, NASA's Chandra X-ray Observatory illustrates the importance of fine angular resolution for x-ray astronomy. Indeed, the future of x-ray astronomy relies upon x-ray telescopes with comparable angular resolution but larger aperture areas. Combined with the special requirements of nested grazing-incidence optics, mass, and envelope constraints of space-borne telescopes render such advances technologically and programmatically challenging. The goal of this technology research is to enable the cost-effective fabrication of large-area, lightweight grazing-incidence x-ray optics with subarcsecond resolution. Toward this end, the project is developing active x-ray optics using slumped-glass mirrors with thin-film piezoelectric arrays for correction of intrinsic or mount-induced distortions.

THE PLERIONIC SUPERNOVA REMNANT G21.5-0.9 POWERED BY PSR J1833-1034: NEW SPECTROSCOPIC AND IMAGING RESULTS REVEALED WITH THE CHANDRA X-RAY OBSERVATORY

International Nuclear Information System (INIS)

Matheson, Heather; Safi-Harb, Samar

2010-01-01

In 1999, the Chandra X-ray Observatory revealed a 150'' radius halo surrounding the 40'' radius pulsar wind nebula (PWN) G21.5-0.9. A 2005 imaging study of G21.5-0.9 showed that the halo is limb-brightened and suggested that this feature is a candidate for the long-sought supernova remnant (SNR) shell. We present a spectral analysis of SNR G21.5-0.9, using the longest effective observation to date (578.6 ks with the Advanced CCD Imaging Spectrometer (ACIS) and 278.4 ks with the High-Resolution Camera (HRC)) to study unresolved questions about the spectral nature of remnant features, such as the limb brightening of the X-ray halo and the bright knot in the northern part of the halo. The Chandra analysis favors the non-thermal interpretation of the limb. Its spectrum is fit well with a power-law model with a photon index Γ = 2.13 (1.94-2.33) and a luminosity of L x (0.5-8 keV) = (2.3 ± 0.6) x 10 33 erg s -1 (at an assumed distance of 5.0 kpc). An srcut model was also used to fit the spectrum between the radio and X-ray energies. While the absence of a shell in the radio still prohibits constraining the spectrum at radio wavelengths, we assume a range of spectral indices to infer the 1 GHz flux density and the rolloff frequency of the synchrotron spectrum in X-rays and find that the maximum energy to which electrons are accelerated at the shock ranges from ∼60 to 130 TeV (B/10 μG) -1/2 , where B is the magnetic field in units of μG. For the northern knot, we constrain previous models and find that a two-component power-law (or srcut) + pshock model provides an adequate fit, with the pshock model requiring a very low ionization timescale and solar abundances for Mg and Si. Our spectroscopic study of PSR J1833-1034, the highly energetic pulsar powering G21.5-0.9, shows that its spectrum is dominated by hard non-thermal X-ray emission with some evidence of a thermal component that represents ∼9% of the observed non-thermal emission and that suggests non

Infrared Counterparts to Chandra X-Ray Sources in the Antennae

Science.gov (United States)

Clark, D. M.; Eikenberry, S. S.; Brandl, B. R.; Wilson, J. C.; Carson, J. C.; Henderson, C. P.; Hayward, T. L.; Barry, D. J.; Ptak, A. F.; Colbert, E. J. M.

2007-03-01

We use deep J (1.25 μm) and Ks (2.15 μm) images of the Antennae (NGC 4038/4039) obtained with the Wide-field InfraRed Camera on the Palomar 200 inch (5 m) telescope, together with the Chandra X-ray source list of Zezas and coworkers to search for infrared counterparts to X-ray point sources. We establish an X-ray/IR astrometric frame tie with ~0.5" rms residuals over a ~4.3' field. We find 13 ``strong'' IR counterparts brighter than Ks=17.8 mag and 99.9% confidence level that IR counterparts to X-ray sources are ΔMKs~1.2 mag more luminous than average non-X-ray clusters. We also note that the X-ray/IR matches are concentrated in the spiral arms and ``overlap'' regions of the Antennae. This implies that these X-ray sources lie in the most ``super'' of the Antennae's super star clusters, and thus trace the recent massive star formation history here. Based on the NH inferred from the X-ray sources without IR counterparts, we determine that the absence of most of the ``missing'' IR counterparts is not due to extinction, but that these sources are intrinsically less luminous in the IR, implying that they trace a different (possibly older) stellar population. We find no clear correlation between X-ray luminosity classes and IR properties of the sources, although small-number statistics hamper this analysis.

Chandra reveals a black hole X-ray binary within the ultraluminous supernova remnant MF 16

Science.gov (United States)

Roberts, T. P.; Colbert, E. J. M.

2003-06-01

We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraordinary X-ray luminosity of the MF 16 supernova remnant actually arises in a black hole X-ray binary. This conclusion is drawn from the point-like nature of the X-ray source, its X-ray spectrum closely resembling the spectrum of other ultraluminous X-ray sources thought to be black hole X-ray binary systems, and the detection of rapid hard X-ray variability from the source. We briefly discuss the nature of the hard X-ray variability, and the origin of the extreme radio and optical luminosity of MF 16 in light of this identification.

CHANDRA OBSERVATIONS OF A 1.9 kpc SEPARATION DOUBLE X-RAY SOURCE IN A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS GALAXY AT z = 0.16

International Nuclear Information System (INIS)

Comerford, Julia M.; Pooley, David; Gerke, Brian F.; Madejski, Greg M.

2011-01-01

We report Chandra observations of a double X-ray source in the z = 0.1569 galaxy SDSS J171544.05+600835.7. The galaxy was initially identified as a dual active galactic nucleus (AGN) candidate based on the double-peaked [O III] λ5007 emission lines, with a line-of-sight velocity separation of 350 km s -1 , in its Sloan Digital Sky Survey spectrum. We used the Kast Spectrograph at Lick Observatory to obtain two long-slit spectra of the galaxy at two different position angles, which reveal that the two Type 2 AGN emission components have not only a velocity offset, but also a projected spatial offset of 1.9 h -1 70 kpc on the sky. Chandra/ACIS observations of two X-ray sources with the same spatial offset and orientation as the optical emission suggest that the galaxy most likely contains Compton-thick dual AGNs, although the observations could also be explained by AGN jets. Deeper X-ray observations that reveal Fe K lines, if present, would distinguish between the two scenarios. The observations of a double X-ray source in SDSS J171544.05+600835.7 are a proof of concept for a new, systematic detection method that selects promising dual AGN candidates from ground-based spectroscopy that exhibits both velocity and spatial offsets in the AGN emission features.

Chandra observations of Jupiter's X-ray Aurora during Juno upstream and apojove intervals

Science.gov (United States)

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

2017-12-01

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. These campaigns were planned following the Juno orbit correction to capitalise on the opportunity to image the X-ray emission while Juno was orbiting close to the expected position of the magnetopause. Previous work has suggested that the auroral X-ray emissions map close to the magnetopause boundary [e.g. Vogt et al., 2015; Kimura et al., 2016; Dunn et al., 2016] and thus in situ spacecraft coverage in this region combined with remote observation of the X-rays afford the chance to constrain the drivers of these energetic emissions and determine if they originate on open or closed field lines. We aim to examine possible drivers of X-ray emission including reconnection and the Kelvin-Helmholtz instability and to explore the role of the solar wind in controlling the emissions. 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 ks 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.

Discovery of X-Ray Emission from the Crab Pulsar at Pulse Minimum

Science.gov (United States)

Tennant, Allyn F.; Becker, Werner; Juda, Michael; Elsner, Ronald F.; Kolodziejczak, Jeffery J.; Murray, Stephen S.; ODell, Stephen L.; Paerels, Frits; Swartz, Douglas A.

2001-01-01

The Chandra X-Ray Observatory observed the Crab pulsar using the Low-Energy Transmission Grating with the High-Resolution Camera. Time-resolved zeroth-order images reveal that the pulsar emits X-rays at all pulse phases. Analysis of the flux at minimum - most likely non-thermal in origin - places an upper limit (T(sub infinity) < 2.1 MK) on the surface temperature of the underlying neutron star. In addition, analysis of the pulse profile establishes that the error in the Chandra-determined absolute time is quite small, -0.2 +/- 0.1 ms.

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.

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.

A CHANDRA SURVEY OF THE X-RAY PROPERTIES OF BROAD ABSORPTION LINE RADIO-LOUD QUASARS

International Nuclear Information System (INIS)

Miller, B. P.; Brandt, W. N.; Garmire, G. P.; Gibson, R. R.; Shemmer, O.

2009-01-01

This work presents the results of a Chandra study of 21 broad absorption line (BAL) radio-loud quasars (RLQs). We conducted a Chandra snapshot survey of 12 bright BAL RLQs selected from Sloan Digital Sky Survey Data/Faint Images of the Radio Sky data and possessing a wide range of radio and C IV absorption properties. Optical spectra were obtained nearly contemporaneously with the Hobby-Eberly Telescope; no strong flux or BAL variability was seen between epochs. In addition to the snapshot targets, we include in our sample nine additional BAL RLQs possessing archival Chandra coverage. We compare the properties of (predominantly high-ionization) BAL RLQs to those of non-BAL RLQs as well as to BAL radio-quiet quasars (RQQs) and non-BAL RQQs for context. All 12 snapshots and 8/9 archival BAL RLQs are detected, with observed X-ray luminosities less than those of non-BAL RLQs having comparable optical/UV luminosities by typical factors of 4.1-8.5. (BAL RLQs are also X-ray weak by typical factors of 2.0-4.5 relative to non-BAL RLQs having both comparable optical/UV and radio luminosities.) However, BAL RLQs are not as X-ray weak relative to non-BAL RLQs as are BAL RQQs relative to non-BAL RQQs. While some BAL RLQs have harder X-ray spectra than typical non-BAL RLQs, some have hardness ratios consistent with those of non-BAL RLQs, and there does not appear to be a correlation between X-ray weakness and spectral hardness, in contrast to the situation for BAL RQQs. RLQs are expected to have X-ray continuum contributions from both accretion-disk corona and small-scale jet emission. While the entire X-ray continuum in BAL RLQs cannot be obscured to the same degree as in BAL RQQs, we calculate that the jet is likely partially covered in many BAL RLQs. We comment briefly on implications for geometries and source ages in BAL RLQs.

Cometary X-rays - the View After the First Chandra Cycle

Science.gov (United States)

Lisse, Carey M.

2001-09-01

The unexpected discovery of x-ray emission from Comet Hyakutake in March 1996 (Lisse et al. 1996) has produced a number of questions about the physical mechanism producing the radiation. The original detection and subsequent observations (Dennerl et al. 1997, Mumma et al. 1997, Krasnopolsky et al. 1998, Owens et al. 1998, Lisse et al. 1999) have shown that the very soft (best fit thermal bremsstrahlung model kT 0.2 keV) emission is due to an interaction between the solar wind and the comet's atmosphere. Using the results from the 15 comets detected to date in x-rays, we report on the latest results on cometary x-ray emission, including new results from Chandra and XMM. As-observed morphologies, spectra, and light curves will be discussed. Our emphasis will be on understanding the physical mechanism producing the emission, and using this to determine the nature of the cometary coma, the structure of the solar wind in the heliosphere, and the source of the local soft x-ray background. This work has been graciously supported by grants from the NASA Planetary Astronomy and Astrophysical Data Programs.

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.; 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,

Simultaneous Chandra and VLA Observations of the Transitional Millisecond Pulsar PSR J1023+0038: Anti-correlated X-Ray and Radio Variability

Science.gov (United States)

Bogdanov, Slavko; Deller, Adam T.; Miller-Jones, James C. A.; Archibald, Anne M.; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D’Angelo, Caroline

2018-03-01

We present coordinated Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations of the transitional millisecond pulsar PSR J1023+0038 in its low-luminosity accreting state. The unprecedented five hours of strictly simultaneous X-ray and radio continuum coverage for the first time unambiguously show a highly reproducible, anti-correlated variability pattern. The characteristic switches from the X-ray high mode into a low mode are always accompanied by a radio brightening with a duration that closely matches the X-ray low mode interval. This behavior cannot be explained by a canonical inflow/outflow accretion model where the radiated emission and the jet luminosity are powered by, and positively correlated with, the available accretion energy. We interpret this phenomenology as alternating episodes of low-level accretion onto the neutron star during the X-ray high mode that are interrupted by rapid ejections of plasma by the active rotation-powered pulsar, possibly initiated by a reconfiguration of the pulsar magnetosphere, that cause a transition to a less X-ray luminous mode. The observed anti-correlation between radio and X-ray luminosity has an additional consequence: transitional MSPs can make excursions into a region of the radio/X-ray luminosity plane previously thought to be occupied solely by black hole X-ray binary sources. This complicates the use of this luminosity relation for identifying candidate black holes, suggesting the need for additional discriminants when attempting to establish the true nature of the accretor.

SERENDIPITOUS DETECTION OF X-RAY EMISSION FROM THE HOT BORN-AGAIN CENTRAL STAR OF THE PLANETARY NEBULA K 1-16

Energy Technology Data Exchange (ETDEWEB)

Montez, Rodolfo Jr. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Kastner, Joel H., E-mail: rodolfo.montez.jr@gmail.com, E-mail: jhk@cis.rit.edu [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

2013-03-20

We report the serendipitous detection of point-like X-ray emission from the hot, PG1159-type central star of the planetary nebula (CSPN) K 1-16 by the XMM-Newton and Chandra X-Ray Observatories. The CSPN lies superimposed on a galaxy cluster that includes an X-ray-bright quasar, but we have successfully isolated the CSPN X-ray emission from the strong diffuse background contributed by the quasar and intracluster gas. We have modeled the XMM-Newton and Chandra X-ray data, taking advantage of the contrasting detection efficiencies of the two observatories to better constrain the low-energy spectral response of Chandra's Advanced CCD Imaging Spectrometer. We find that the CSPN X-ray spectrum is well characterized by the combination of a non-local thermodynamic equilibrium model atmosphere with T{sub *} {approx} 135 kK and a carbon-rich, optically thin thermal plasma with T{sub X} {approx} 1 MK. These results for X-ray emission from the K 1-16 CSPN, combined with those obtained for other PG1159-type objects, lend support to the 'born-again' scenario for Wolf-Rayet and PG1159 CSPNe, wherein a late helium shell flash dredges up carbon-rich intershell material and ejects this material into the circumstellar environment.

CHANDRA ACIS SURVEY OF X-RAY POINT SOURCES: THE SOURCE CATALOG

Energy Technology Data Exchange (ETDEWEB)

Wang, Song; Liu, Jifeng; Qiu, Yanli; Bai, Yu; Yang, Huiqin; Guo, Jincheng; Zhang, Peng, E-mail: jfliu@bao.ac.cn, E-mail: songw@bao.ac.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2016-06-01

The Chandra archival data is a valuable resource for various studies on different X-ray astronomy topics. In this paper, we utilize this wealth of information and present a uniformly processed data set, which can be used to address a wide range of scientific questions. The data analysis procedures are applied to 10,029 Advanced CCD Imaging Spectrometer observations, which produces 363,530 source detections belonging to 217,828 distinct X-ray sources. This number is twice the size of the Chandra Source Catalog (Version 1.1). The catalogs in this paper provide abundant estimates of the detected X-ray source properties, including source positions, counts, colors, fluxes, luminosities, variability statistics, etc. Cross-correlation of these objects with galaxies shows that 17,828 sources are located within the D {sub 25} isophotes of 1110 galaxies, and 7504 sources are located between the D {sub 25} and 2 D {sub 25} isophotes of 910 galaxies. Contamination analysis with the log N –log S relation indicates that 51.3% of objects within 2 D {sub 25} isophotes are truly relevant to galaxies, and the “net” source fraction increases to 58.9%, 67.3%, and 69.1% for sources with luminosities above 10{sup 37}, 10{sup 38}, and 10{sup 39} erg s{sup −1}, respectively. Among the possible scientific uses of this catalog, we discuss the possibility of studying intra-observation variability, inter-observation variability, and supersoft sources (SSSs). About 17,092 detected sources above 10 counts are classified as variable in individual observation with the Kolmogorov–Smirnov (K–S) criterion ( P {sub K–S} < 0.01). There are 99,647 sources observed more than once and 11,843 sources observed 10 times or more, offering us a wealth of data with which to explore the long-term variability. There are 1638 individual objects (∼2350 detections) classified as SSSs. As a quite interesting subclass, detailed studies on X-ray spectra and optical spectroscopic follow-up are needed to

Rejuvenation of the Innocent Bystander: Results from a Pilot X-ray Study of Dwarf Carbon Stars

Science.gov (United States)

Mazzoni, Fernando; Montez, Rodolfo; Green, Paul

2018-01-01

We present the results of a pilot study by the Chandra X-ray Observatory of X-ray emission from dwarf Carbon (dC) stars. Carbon stars were thought to be exclusively AGB stars but main sequence dwarfs showing carbon molecular bands appear to be the dominant variety. The existence of dC stars is surprising since dwarf stars cannot intrinsically produce carbon as an AGB star can. It is hypothesized that dC stars are polluted by an evolved companion star. Evidence of past pollution can appear in X-ray emission where increased coronal activity (“spin-up”) or mass accretion via a disk can be detected. Using the Chandra X-ray Observatory we detected X-ray photons in the vicinity of all the dC stars in our a pilot sample. For each detection we characterized the X-ray emission and compared to the emission expected from potential emission scenarios. Although the process that produces the X-ray emission from dC stars is presently unclear and our pilot sample is small, our results suggest that X-ray emission might be a universal characteristic of dC stars. Further examination of the X-ray emission plus future X-ray and multiwavelength observations will help us better understand the nature of these intriguing stars.

Chandra Looks Over a Cosmic Four-Leaf Clover

Science.gov (United States)

2004-07-01

A careful analysis of observations by NASA's Chandra X-ray Observatory of a rare quadruple quasar has uncovered evidence that possibly a single star in a foreground galaxy magnified X-rays coming from the quasar. This discovery gives astronomers a new and extremely precise probe of the gas flow around the supermassive black hole that powers the quasar. "If our interpretation is correct, then we are seeing details around this black hole that are 50,000 times smaller than either the Hubble Space Telescope or Chandra could see under ordinary circumstances," said George Chartas of Penn State University in University Park, and lead author of a recent article on the Cloverleaf quasar in The Astrophysical Journal. The Cloverleaf quasar is a single object about 11 billion light years from Earth that appears as four images produced by a process known as gravitational lensing. If one or more galaxies lie along the line of sight to a more distant quasar, the gravitational field of the intervening galaxies can bend and magnify the light from the quasar and produce multiple images of it. The four images of the Cloverleaf quasar have been produced by one or more intervening galaxies. Cloverleaf Quasar Chandra X-ray Image of the Cloverleaf quasar One of the images (A), in the Cloverleaf is brighter than the others in both optical and X-ray light. Chartas and his colleagues found the relative brightness of this image was greater in X-ray than in optical light. The X-rays from iron atoms were also enhanced relative to X-rays at lower energies. Since the amount of brightening due to gravitational lensing does not vary with the wavelength, this means that an additional object has magnified the X-rays. The increased magnification of the X-ray light can be explained by gravitational microlensing, an effect which has been used to search for compact stars and planets in our galaxy. Microlensing occurs when a star or a multiple star system passes in front of light from a background object

Chandra Sees Remarkable Eclipse of Black Hole

Science.gov (United States)

2007-04-01

A remarkable eclipse of a supermassive black hole and the hot gas disk around it has been observed with NASA's Chandra X-ray Observatory. This eclipse has allowed two key predictions about the effects of supermassive black holes to be tested. Just as eclipses of the Sun and moon give astronomers rare opportunities to learn about those objects, an alignment in a nearby galaxy has provided a rare opportunity to investigate a supermassive black hole. Illustrations of Black Hole Eclipse Illustrations of Black Hole Eclipse The supermassive black hole is located in NGC 1365, a galaxy 60 million light years from Earth. It contains a so called active galactic nucleus, or AGN. Scientists believe that the black hole at the center of the AGN is fed by a steady stream of material, presumably in the form of a disk. Material just about to fall into a black hole should be heated to millions of degrees before passing over the event horizon, or point of no return. The disk of gas around the central black hole in NGC 1365 produces copious X-rays but is much too small to resolve directly with a telescope. However, the disk was eclipsed by an intervening cloud, so observation of the time taken for the disk to go in and out of eclipse allowed scientists to estimate the size of the disk. Black Hole Animation Black Hole Animation "For years we've been struggling to confirm the size of this X-ray structure," said Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass, and the Italian Institute of Astronomy (INAF). "This serendipitous eclipse enabled us to make this breakthrough." The Chandra team directly measured the size of the X-ray source as about seven times the distance between the Sun and the Earth. That means the source of X-rays is about 2 billion times smaller than the host galaxy and only about 10 times larger than the estimated size of the black hole's event horizon, consistent with theoretical predictions. Chandra X-ray Image of NGC 1365

Laboratory simulation of charge exchange-produced X-ray emission from comets.

Science.gov (United States)

Beiersdorfer, P; Boyce, K R; Brown, G V; Chen, H; Kahn, S M; Kelley, R L; May, M; Olson, R E; Porter, F S; Stahle, C K; Tillotson, W A

2003-06-06

In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory.

NASA's Great Observatories Celebrate the International Year of Astronomy

Science.gov (United States)

2009-01-01

[figure removed for brevity, see original site] Click on the image for larger version In 1609, Galileo improved the newly invented telescope, turned it toward the heavens, and revolutionized our view of the universe. In celebration of the 400th anniversary of this milestone, 2009 has been designated as the International Year of Astronomy. Today, NASA's Great Observatories are continuing Galileo's legacy with stunning images and breakthrough science from the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory. While Galileo observed the sky using visible light seen by the human eye, technology now allows us to observe in many wavelengths, including Spitzer's infrared view and Chandra's view in X-rays. Each wavelength region shows different aspects of celestial objects and often reveals new objects that could not otherwise be studied. This image of the spiral galaxy Messier 101 is a composite of views from Spitzer, Hubble, and Chandra. The red color shows Spitzer's view in infrared light. It highlights the heat emitted by dust lanes in the galaxy where stars can form. The yellow color is Hubble's view in visible light. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes. The blue color shows Chandra's view in X-ray light. Sources of X-rays include million-degree gas, exploded stars, and material colliding around black holes. Such composite images allow astronomers to see how features seen in one wavelength match up with those seen in another wavelength. It's like seeing with a camera, night vision goggles, and X-ray vision all at once. In the four centuries since Galileo, astronomy has changed dramatically. Yet our curiosity and quest for knowledge remain the same. So, too, does our wonder at the splendor of the universe. The International Year of Astronomy Great Observatories Image Unveiling is supported by the NASA Science Mission Directorate Astrophysics Division. The project is a

Cometary X-ray Emission: the View After the First Chandra Observations

Science.gov (United States)

Lisse, C. M.

2002-01-01

The unexpected discovery of x-ray emission from Comet Hyakutake in March 1996 (Lisse et al. 1996) has produced a number of questions about the physical mechanism producing the radiation. The original detection and subsequent observations (Dennerl et al. 1997, Mumma et al. 1997, Krasnopolsky et al. 1998, Owens et al. 1998, Lisse et al. 1999) have shown that the very soft (best fit thermal bremsstrahlung model kT ~ 0.2 keV) emission is due to an interaction between the solar wind and the comet's atmosphere. Using the results from the 15 comets detected to date in x-rays, we report on the latest results on cometary x-ray emission, including new results from Chandra and XMM. As-observed morphologies, spectra, and light curves will be discussed. Our emphasis will be on understanding the physical mechanism producing the emission, and using this to determine the nature of the cometary coma, the structure of the solar wind in the heliosphere, and the source of the local soft x-ray background. This work has been graciously supported by grants from the NASA Planetary Astronomy and Astrophysical Data Programs.

THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

Energy Technology Data Exchange (ETDEWEB)

Weisskopf, Martin C.; Elsner, Ronald F.; O' Dell, Stephen L.; Tennant, Allyn F. [NASA Marshall Space Flight Center, Space Science Office, VP62, Huntsville, AL 35812 (United States); Romani, Roger W. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Razzano, Massimiliano [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Belfiore, Andrea; Saz Parkinson, Pablo; Ziegler, Marcus; Dormody, Michael [Santa Cruz Institute for Particle Physics, Department of Physics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Ray, Paul S. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kerr, Matthew [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States); Harding, Alice [Astrophysics Science Division, NASA Goddard Space Flight Center, Code 663, Greenbelt, MD 20771 (United States); Swartz, Douglas A. [Universities Space Research Association, NASA Marshall Space Flight Center, Space Science Office, VP62, Huntsville, AL 35812 (United States); Carraminana, Alberto [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, Tonantzintla, Puebla 72840 (Mexico); Becker, Werner; Kanbach, Gottfried [Max-Planck-Institut fuer extraterrestrische Physik, 85741 Garching bei Muenchen (Germany); De Luca, Andrea [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy); Thompson, David J. [Astroparticle Physics Laboratory, NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States)

2011-12-10

We report the probable identification of the X-ray counterpart to the {gamma}-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20{sup h}21{sup m}30.{sup s}733, decl. +40 Degree-Sign 26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to {gamma}-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.

THE IDENTIFICATION OF THE X-RAY COUNTERPART TO PSR J2021+4026

International Nuclear Information System (INIS)

Weisskopf, Martin C.; Elsner, Ronald F.; O'Dell, Stephen L.; Tennant, Allyn F.; Romani, Roger W.; Razzano, Massimiliano; Belfiore, Andrea; Saz Parkinson, Pablo; Ziegler, Marcus; Dormody, Michael; Ray, Paul S.; Kerr, Matthew; Harding, Alice; Swartz, Douglas A.; Carramiñana, Alberto; Becker, Werner; Kanbach, Gottfried; De Luca, Andrea; Thompson, David J.

2011-01-01

We report the probable identification of the X-ray counterpart to the γ-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20 h 21 m 30. s 733, decl. +40°26'46.''04 (J2000) with an estimated uncertainty of 1.''3 combined statistical and systematic error. Moreover, both the X-ray to γ-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' > 23.0 mag and r' > 25.2 mag. The source exhibits an X-ray spectrum with most likely both a power law and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.

Development Roadmap for an Adjustable X-Ray Optics Observatory

Science.gov (United States)

Schwartz, Dan; Brissenden, R.; Bookbinder, J.; Davis, W.; Forman, W.; Freeman, M.; O'Dell, S.; Ramsey, B.; Reid, P.; Romaine, S.;

X-Ray Outburst from Young Star in McNeil's Nebula

Science.gov (United States)

2004-07-01

Observations with NASA's Chandra X-ray Observatory captured an X-ray outburst from a young star, revealing a probable scenario for the intermittent brightening of the recently discovered McNeil's Nebula. It appears the interaction between the young star's magnetic field and an orbiting disk of gas can cause dramatic, episodic increases in the light from the star and disk, illuminating the surrounding gas. "The story of McNeil's Nebula is a wonderful example of the importance of serendipity in science," said Joel Kastner of the Rochester Institute of Technology in Rochester, New York, lead author of a paper in the July 22 issue of Nature describing the X-ray results. "Visible-light images were made of this region several months before Jay McNeil made his discovery, so it could be determined approximately when and by how much the star flared up to produce McNeil's Nebula." The small nebula, which lies in the constellation Orion about 1300 light years from Earth, was discovered with a 3-inch telescope by McNeil, an amateur astronomer from Paducah, Kentucky, in January 2004. In November 2002, a team led by Ted Simon of the Institute for Astronomy in Hawaii had observed the star-rich region with Chandra in search of young, X-ray emitting stars, and had detected several objects. Optical and infrared astronomers had, as part of independent surveys, also observed the region about a year later, in 2003. After the announcement of McNeil's discovery, optical, infrared and X-ray astronomers rushed to observe the region again. They found that a young star buried in the nebula had flared up, and was illuminating the nebula. This star was coincident with one of the X-ray sources discovered earlier by Simon. Chandra observations obtained by Kastner's group just after the optical outburst showed that the source had brightened fifty-fold in X-rays when compared to Simon's earlier observation. The visible-light eruption provides evidence that the cause of the X-ray outburst is the

The Einstein Observatory stellar X-ray database

International Nuclear Information System (INIS)

Harnden, F.R. Jr.; Sciortino, S.; Micela, G.; Maggio, A.; Schmitt, J.H.M.M.

1990-01-01

We present the motivation for and methodology followed in constructing the Einstein Observatory Stellar X-ray Database from a uniform analysis of nearly 4000 Imaging Proportional Counter fields obtained during the life of this mission. This project has been implemented using the INGRES database system, so that statistical analyses of the properties of detected X-ray sources are relatively easily and flexibly accomplished. Some illustrative examples will furnish a general view both of the kind and amount of the archived information and of the statistical approach used in analyzing the global properties of the data. (author)

Deconvolving the Nucleus of Centaurus A Using Chandra PSF Library

Science.gov (United States)

Karovska, Margarita

2000-01-01

Centaurus A (NGC 5128) is a giant early-type galaxy containing the nearest (at 3.5 Mpc) radio-bright Active Galactic Nucleus (AGN). Cen A was observed with the High Resolution Camera (HRC) on the Chandra X-ray Observatory on several occasions since the launch in July 1999. The high-angular resolution (less than 0.5 arcsecond) Chandra/HRC images reveal X ray multi-scale structures in this object with unprecedented detail and clarity, including the bright nucleus believed to be associated with a supermassive black hole. We explored the spatial extent of the Cen A nucleus using deconvolution techniques on the full resolution Chandra images. Model point spread functions (PSFs) were derived from the standard Chandra raytrace PSF library as well as unresolved point sources observed with Chandra. The deconvolved images show that the Cen A nucleus is resolved and asymmetric. We discuss several possible causes of this extended emission and of the asymmetries.

The Large Observatory For x-ray Timing

DEFF Research Database (Denmark)

Feroci, M.; Herder, J. W. den; Bozzo, E.

2014-01-01

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final down-selection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study th...

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.

The Wide Field Imager of the International X-ray Observatory

Energy Technology Data Exchange (ETDEWEB)

Stefanescu, A., E-mail: astefan@hll.mpg.d [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany); Johannes Gutenberg-Universitaet, Inst. f. anorganische und analytische Chemie, 55099 Mainz (Germany); Bautz, M.W. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 (United States); Burrows, D.N. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Bombelli, L.; Fiorini, C. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, Milano (Italy); INFN Sezione di Milano, Milano (Italy); Fraser, G. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Heinzinger, K. [PNSensor GmbH, Roemerstr. 28, 80803 Muenchen (Germany); Herrmann, S. [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany); Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstr., 85748 Garching (Germany); Kuster, M. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Schlossgartenstr. 9, 64289 Darmstadt (Germany); Lauf, T. [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany); Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstr., 85748 Garching (Germany); Lechner, P. [PNSensor GmbH, Roemerstr. 28, 80803 Muenchen (Germany); Lutz, G. [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany); Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Majewski, P. [PNSensor GmbH, Roemerstr. 28, 80803 Muenchen (Germany); Meuris, A. [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany); Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstr., 85748 Garching (Germany); Murray, S.S. [Harvard/Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

2010-12-11

The International X-ray Observatory (IXO) will be a joint X-ray observatory mission by ESA, NASA and JAXA. It will have a large effective area (3 m{sup 2} at 1.25 keV) grazing incidence mirror system with good angular resolution (5 arcsec at 0.1-10 keV) and will feature a comprehensive suite of scientific instruments: an X-ray Microcalorimeter Spectrometer, a High Time Resolution Spectrometer, an X-ray Polarimeter, an X-ray Grating Spectrometer, a Hard X-ray Imager and a Wide-Field Imager. The Wide Field Imager (WFI) has a field-of-view of 18 ftx18 ft. It will be sensitive between 0.1 and 15 keV, offer the full angular resolution of the mirrors and good energy resolution. The WFI will be implemented as a 6 in. wafer-scale monolithical array of 1024x1024 pixels of 100x100{mu}m{sup 2} size. The DEpleted P-channel Field-Effect Transistors (DEPFET) forming the individual pixels are devices combining the functionalities of both detector and amplifier. Signal electrons are collected in a potential well below the transistor's gate, modulating the transistor current. Even when the device is powered off, the signal charge is collected and kept in the potential well below the gate until it is explicitly cleared. This makes flexible and fast readout modes possible.

Chandra Observations of Neutron Stars: An Overview

Science.gov (United States)

Weisskopf, Martin C.; Karovska, M.; Pavlov, G. G.; Zavlin, V. E.; Clarke, Tracy

2006-01-01

We present a brief review of Chandra X-ray Observatory observations of 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 an admittedly biased and overly brief overview of these observations, highlighting some new discoveries made possible by the Observatory's unique capabilities. We also include our analysis of recent multiwavelength observations of the putative pulsar and its pulsar-wind nebula in the IC 443 SNR.

Jet Power and Black Hole Assortment Revealed in New Chandra Image

Science.gov (United States)

2008-01-01

acceleration in this part of the jet is unknown. Hundreds of point-like sources are also seen in the Chandra image. Many of these are X-ray binaries that contain a stellar-mass black hole and a companion star in orbit around one another. Determining the population and properties of these black holes should help scientists better understand the evolution of massive stars and the formation of black holes. Another surprise was the detection of two particularly bright X-ray binaries. These sources may contain stellar mass black holes that are unusually massive, and this Chandra observation might have caught them gobbling up material at a high rate. In this image, low-energy X-rays are colored red, intermediate-energy X-rays are green, and the highest-energy X-rays detected by Chandra are blue. The dark green and blue bands running almost perpendicular to the jet are dust lanes that absorb X-rays. This dust lane was created when Centaurus A merged with another galaxy perhaps 100 million years ago. This research was presented at the American Astronomical Society meeting on January 9th by Gregory Sivakoff (The Ohio State University). Other team members include Ralph Kraft (Harvard-Smithsonian Center for Astrophysics), Martin Hardcastle (University of Hertfordshire), Diana Worrall (University of Bristol), and Andres Jordan (Smithsonian Astrophysical Observatory). NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Active x-ray optics for high resolution space telescopes

Science.gov (United States)

Doel, Peter; Atkins, Carolyn; Brooks, D.; Feldman, Charlotte; Willingale, Richard; Button, Tim; Rodriguez Sanmartin, Daniel; Meggs, Carl; James, Ady; Willis, Graham; Smith, Andy

2017-11-01

The Smart X-ray Optics (SXO) Basic Technology project started in April 2006 and will end in October 2010. The aim is to develop new technologies in the field of X-ray focusing, in particular the application of active and adaptive optics. While very major advances have been made in active/adaptive astronomical optics for visible light, little was previously achieved for X-ray optics where the technological challenges differ because of the much shorter wavelengths involved. The field of X-ray astronomy has been characterized by the development and launch of ever larger observatories with the culmination in the European Space Agency's XMM-Newton and NASA's Chandra missions which are currently operational. XMM-Newton uses a multi-nested structure to provide modest angular resolution ( 10 arcsec) but large effective area, while Chandra sacrifices effective area to achieve the optical stability necessary to provide sub-arc second resolution. Currently the European Space Agency (ESA) is engaged in studies of the next generation of X-ray space observatories, with the aim of producing telescopes with increased sensitivity and resolution. To achieve these aims several telescopes have been proposed, for example ESA and NASA's combined International X-ray Observatory (IXO), aimed at spectroscopy, and NASA's Generation-X. In the field of X-ray astronomy sub 0.2 arcsecond resolution with high efficiency would be very exciting. Such resolution is unlikely to be achieved by anything other than an active system. The benefits of a such a high resolution would be important for a range of astrophysics subjects, for example the potential angular resolution offered by active X-ray optics could provide unprecedented structural imaging detail of the Solar Wind bowshock interaction of comets, planets and similar objects and auroral phenomena throughout the Solar system using an observing platform in low Earth orbit. A major aim of the SXO project was to investigate the production of thin

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.

CHANDRA ACIS SURVEY OF X-RAY POINT SOURCES IN NEARBY GALAXIES. II. X-RAY LUMINOSITY FUNCTIONS AND ULTRALUMINOUS X-RAY SOURCES

Energy Technology Data Exchange (ETDEWEB)

Wang, Song; Qiu, Yanli; Liu, Jifeng [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Bregman, Joel N., E-mail: songw@bao.ac.cn, E-mail: jfliu@bao.ac.cn [University of Michigan, Ann Arbor, MI 48109 (United States)

2016-09-20

Based on the recently completed Chandra /ACIS survey of X-ray point sources in nearby galaxies, we study the X-ray luminosity functions (XLFs) for X-ray point sources in different types of galaxies and the statistical properties of ultraluminous X-ray sources (ULXs). Uniform procedures are developed to compute the detection threshold, to estimate the foreground/background contamination, and to calculate the XLFs for individual galaxies and groups of galaxies, resulting in an XLF library of 343 galaxies of different types. With the large number of surveyed galaxies, we have studied the XLFs and ULX properties across different host galaxy types, and confirm with good statistics that the XLF slope flattens from lenticular ( α ∼ 1.50 ± 0.07) to elliptical (∼1.21 ± 0.02), to spirals (∼0.80 ± 0.02), to peculiars (∼0.55 ± 0.30), and to irregulars (∼0.26 ± 0.10). The XLF break dividing the neutron star and black hole binaries is also confirmed, albeit at quite different break luminosities for different types of galaxies. A radial dependency is found for ellipticals, with a flatter XLF slope for sources located between D {sub 25} and 2 D {sub 25}, suggesting the XLF slopes in the outer region of early-type galaxies are dominated by low-mass X-ray binaries in globular clusters. This study shows that the ULX rate in early-type galaxies is 0.24 ± 0.05 ULXs per surveyed galaxy, on a 5 σ confidence level. The XLF for ULXs in late-type galaxies extends smoothly until it drops abruptly around 4 × 10{sup 40} erg s{sup −1}, and this break may suggest a mild boundary between the stellar black hole population possibly including 30 M {sub ⊙} black holes with super-Eddington radiation and intermediate mass black holes.

Middle Tier Services Accessing the Chandra X-Ray Center Data Archive

Science.gov (United States)

Patz, A.; Harbo, P.; Moran, J.; van Stone, D.; Zografou, P.

The Chandra Data Archive team at the Chandra X-ray Center has developed middle tier services that are used by both our search and retrieval applications to uniformly access our data repository. Accessible through an HTTP URL interface, these services can be called by our J2EE web application (WebChaser) and our Java Swing application (Chaser), as well as any other HTTP client. Programs can call the services to retrieve observation data such as a single FITS file, a proposal abstract or a detailed report of observation parameters. Having a central interface to the archive, shared by client applications, facilitates code reusability and easier maintenance. These middle tier services have been written in Java and packaged into a single J2EE application called the Search and Retrieval (SR) Services. The package consists of a web application front-end and an Enterprise Java Beans back-end. This paper describes the design and use of the SR Services.

The galactic luminous supersoft X-ray source RXJ0925.7-4758 / MR ...

Indian Academy of Sciences (India)

Nandita Prodhani

2018-01-30

Jan 30, 2018 ... White dwarf; luminous supersoft X-ray source; luminosity; absorption edge. PACS Nos 97.80.Jp; 97.10.Ri; 98.35.Mp; 97.80.Fk. 1. Introduction. For the last few decades, Einstein observatory, Roent- gen Satellite (ROSAT), ASCA, CHANDRA, XMM-. Newton, SWIFT, SUZAKU and other ingenious devices.

X-Ray Snapshots Capture the First Cries of Baby Stars

Science.gov (United States)

2000-11-01

CXC PR: 00-27 Stars, like babies, make quite a fuss in their first days after birth. Astronomers using the Chandra X-ray Observatory have discovered that protostars--stars in their youngest, "neonatal" stage--are marked by powerful X rays from plasma ten times hotter and 100 to 100,000 times brighter than the flares on our Sun. This is all long before their nuclear furnaces of hydrogen even ignite, the mark of stellar maturity. The X-ray flares have also provided the closest look yet at the youngest stars in the universe, never before detected because they are hidden within dust and molecular clouds that filter all other types of light. Yohko Tsuboi of the Pennsylvania State University (Penn State) presents these findings today in a press conference at the meeting of the High Energy Astrophysics Division of the American Astronomical Society in Honolulu, Hawaii. "We peered at newborn stars deeply embedded in their cradle and found that their crying is much more tumultuous than we expected," said Tsuboi. "With Chandra, we now have a new tool to examine protostars, which have been impossible to gain access to in any other wavelength." Protostars located in the rho-Ophiuchi molecular cloud Protostars located in the rho-Ophiuchi molecular cloud 1 square light years field X-ray image around rho Ophiuchi molecular cloud core. Red colorrepresents less absorbed X rays, while blue represents absorbed X rays. Lightcurves for each sources are also shown. Tsuboi and her collaborators looked at the two youngest types of protostars: Class-0 (zero) protostars, about 10,000 years old; and Class-I protostars, about 100,000 years old. In human terms, these protostars are like one-hour-old and 10-hour-old babies, respectively. The transition from one class to another is marked by changes in the protostar's infrared spectrum as the gas and dust envelope diminishes. The envelope has been well studied by infrared and radio astronomers. Protostars themselves and their most extreme

Chandra Discovers Light Echo from the Milky Way's Black Hole

Science.gov (United States)

2007-01-01

Like cold case investigators, astronomers have used NASA's Chandra X-ray Observatory to uncover evidence of a powerful outburst from the giant black hole at the Milky Way's center. A light echo was produced when X-ray light generated by gas falling into the Milky Way's supermassive black hole, known as Sagittarius A* (pronounced "A-star"), was reflected off gas clouds near the black hole. While the primary X-rays from the outburst would have reached Earth about 50 years ago, the reflected X-rays took a longer path and arrived in time to be recorded by Chandra. Variability in Chandra Images of Light Echo Variability in Chandra Images of Light Echo "This dramatic event happened before we had satellites in space that could detect it," said Michael Muno of the California Institute of Technology in Pasadena. "So, it's remarkable that we can use Chandra to dig into the past and see this monster black hole's capacity for destruction." Previously, scientists have used Chandra to directly detect smaller and more recent outbursts from the black hole. This latest outburst revealed by the X-ray echo was about 1,000 times brighter and lasted well over 1,000 times longer than any of the recent outbursts observed by Chandra. Theory predicts that an outburst from Sagittarius A* would cause X-ray emission from the clouds to vary in both intensity and shape. Muno and his team found these changes for the first time, thus ruling out other interpretations. The latest results corroborate other independent, but indirect, evidence for light echoes generated by the black hole in the more distant past. Illustrations of Light Echo Illustrations of Light Echo Scientists have long known that Sagittarius A*, with a mass of about 3 million suns, lurked at the center for Milky Way. However, the black hole is incredibly faint at all wavelengths, especially in X-rays. "This faintness implies that stars and gas rarely get close enough to the black hole to be in any danger," said co-author Frederick

Chandra X-Rays from the Redshift 7.54 Quasar ULAS J1342+0928

Science.gov (United States)

Bañados, Eduardo; Connor, Thomas; Stern, Daniel; Mulchaey, John; Fan, Xiaohui; Decarli, Roberto; Farina, Emanuele P.; Mazzucchelli, Chiara; Venemans, Bram P.; Walter, Fabian; Wang, Feige; Yang, Jinyi

2018-04-01

We present a 45 ks Chandra observation of the quasar ULAS J1342+0928 at z = 7.54. We detect {14.0}-3.7+4.8 counts from the quasar in the observed-frame energy range 0.5–7.0 keV (6σ detection), representing the most distant non-transient astronomical source identified in X-rays to date. The present data are sufficient only to infer rough constraints on the spectral parameters. We find an X-ray hardness ratio of { \\mathcal H }{ \\mathcal R }=-{0.51}-0.28+0.26 between the 0.5–2.0 keV and 2.0–7.0 keV ranges and derive a power-law photon index of {{Γ }}={1.95}-0.53+0.55. Assuming a typical value for high-redshift quasars of Γ = 1.9, ULAS J1342+0928 has a 2–10 keV rest-frame X-ray luminosity of {L}2-10={11.6}-3.5+4.3× {10}44 {erg} {{{s}}}-1. Its X-ray-to-optical power-law slope is {α }OX}=-{1.67}-0.10+0.16, consistent with the general trend indicating that the X-ray emission in the most bolometrically powerful quasars is weaker relative to their optical emission.

Chandra Reviews Black Hole Musical: Epic But Off-Key

Science.gov (United States)

2006-10-01

A gigantic sonic boom generated by a supermassive black hole has been found with NASA's Chandra X-ray Observatory, along with evidence for a cacophony of deep sound. This discovery was made by using data from the longest X-ray observation ever of M87, a nearby giant elliptical galaxy. M87 is centrally located in the Virgo cluster of galaxies and is known to harbor one of the Universe's most massive black holes. Scientists detected loops and rings in the hot, X-ray emitting gas that permeates the cluster and surrounds the galaxy. These loops provide evidence for periodic eruptions that occurred near the supermassive black hole, and that generate changes in pressure, or pressure waves, in the cluster gas that manifested themselves as sound. Chandra Low Energy X-ray Images of M87 Chandra Low Energy X-ray Images of M87 "We can tell that many deep and different sounds have been rumbling through this cluster for most of the lifetime of the Universe," said William Forman of the Harvard-Smithsonian Center for Astrophysics (CfA). The outbursts in M87, which happen every few million years, prevent the huge reservoir of gas in the cluster from cooling and forming many new stars. Without these outbursts and resultant heating, M87 would not be the elliptical galaxy it is today. "If this black hole wasn't making all of this noise, M87 could have been a completely different type of galaxy," said team member Paul Nulsen, also of the CfA, "possibly a huge spiral galaxy about 30 times brighter than the Milky Way." Chandra High Energy X-ray Image of M87 Chandra High Energy X-ray Image of M87 The outbursts result when material falls toward the black hole. While most of the matter is swallowed, some of it was violently ejected in jets. These jets are launched from regions close to the black hole (neither light nor sound can escape from the black hole itself) and push into the cluster's gas, generating cavities and sound which then propagate outwards. Chandra's M87 observations also

An X-ray Expansion and Proper Motion Study of the Magellanic Cloud Supernova Remnant J0509-6731 with the Chandra X-ray Observatory

Science.gov (United States)

Roper, Quentin; Filipovi, Miroslav; Allen, Glenn E.; Sano, Hidetoshi; Park, Laurence; Pannuti, Thomas G.; Sasaki, Manami; Haberl, Frank; Kavanagh, Patrick J.; Yamane, Yumiko; Yoshiike, Satoshi; Fujii, Kosuke; Fukui, Yasuo; Seitenzahl, Ivo R.

2018-05-01

Using archival Chandra data consisting of a total of 78.46 ksec over two epochs seven years apart, we have measured the expansion of the young (˜400 years old) type Ia Large Magellanic Cloud supernova remnant (SNR) J0509-6731. In addition, we use radial brightness profile matching to detect proper-motion expansion of this SNR, and estimate an speed of 7 500±1 700 km s-1. This is one of the only proper motion studies of extragalactic SNRs expansion that is able to derive an expansion velocity, and one of only two such studies of an extragalactic SNR to yield positive results in the X-rays. We find that this expansion velocity is consistent with an optical expansion study on this object. In addition, we examine the medium into which the SNR is expanding by examining the CO and neutral H I gas using radio data obtained from Mopra, the Australia Telescope Compact Array and Parkes radio telescopes. We also briefly compare this result with a recent radio survey, and find that our results predict a radio spectral index α of -0.67±0.07. This value is consistent with high frequency radio observations of MCSNR J0509-6731.

X-ray observations of solar flares with the Einstein Observatory

International Nuclear Information System (INIS)

Schmitt, J.H.M.M.; Fink, H.; Harnden, F.R. Jr.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA)

1987-01-01

The first Einstein Observatory Imaging Proportional Counter (IPC) observations of solar flares are presented. These flares were detected in scattered X-ray light when the X-ray telescope was pointed at the sunlit earth. The propagation and scattering of solar X-rays in the earth's atmosphere are discussed in order to be able to deduce the solar X-ray flux incident on top of the atmosphere from scattered X-ray intensity measurements. After this correction, the scattered X-ray data are interpreted as full-disk observations of the sun obtained with the same instrumentation used for observations of flares on other stars. Employing the same data analysis and interpretation techniques, extremely good agreement is found between the physical flare parameters deduced from IPC observations and known properties of compact loop flares. This agreement demonstrates that flare observations with the IPC can reveal physical parameters such as temperature and density quite accurately in the solar case and therefore suggests that the interpretations of stellar X-ray flare observations are on a physically sound basis. 26 references

Silicon pore optics for the international x-ray observatory

Science.gov (United States)

Wille, E.; Wallace, K.; Bavdaz, M.; Collon, M. J.; Günther, R.; Ackermann, M.; Beijersbergen, M. W.; Riekerink, M. O.; Blom, M.; Lansdorp, B.; de Vreede, L.

2017-11-01

Lightweight X-ray Wolter optics with a high angular resolution will enable the next generation of X-ray telescopes in space. The International X-ray Observatory (IXO) requires a mirror assembly of 3 m2 effective area (at 1.5 keV) and an angular resolution of 5 arcsec. These specifications can only be achieved with a novel technology like Silicon Pore Optics, which is developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor industry. We present the manufacturing process ranging from single mirror plates towards complete focusing mirror modules mounted in flight configuration. The performance of the mirror modules is tested using X-ray pencil beams or full X-ray illumination. In 2009, an angular resolution of 9 arcsec was achieved, demonstrating the improvement of the technology compared to 17 arcsec in 2007. Further development activities of Silicon Pore Optics concentrate on ruggedizing the mounting system and performing environmental tests, integrating baffles into the mirror modules and assessing the mass production.

Technology Requirements For a Square-Meter, Arcsecond-Resolution Telescope for X-Rays: The SMART-X Mission

Science.gov (United States)

Schwartz, Daniel A.; Allured, Ryan; Bookbinder, Jay; Cotroneo, Vincenzo; Forman, William; Freeman, Mark; McMuldroch, Stuart; Reid, Paul; Tananbaum, Harvey; Vikhlinin, Alexey;

CHANDRA DETECTION OF X-RAY EMISSION FROM ULTRACOMPACT DWARF GALAXIES AND EXTENDED STAR CLUSTERS

International Nuclear Information System (INIS)

Hou, Meicun; Li, Zhiyuan

2016-01-01

We have conducted a systematic study of X-ray emission from ultracompact dwarf (UCD) galaxies and extended star clusters (ESCs), based on archival Chandra observations. Among a sample of 511 UCDs and ESCs complied from the literature, 17 X-ray counterparts with 0.5–8 keV luminosities above ∼5 × 10 36 erg s −1 are identified, which are distributed in eight early-type host galaxies. To facilitate comparison, we also identify X-ray counterparts of 360 globular clusters (GCs) distributed in four of the eight galaxies. The X-ray properties of the UCDs and ESCs are found to be broadly similar to those of the GCs. The incidence rate of X-ray-detected UCDs and ESCs, 3.3% ± 0.8%, while lower than that of the X-ray-detected GCs (7.0% ± 0.4%), is substantially higher than expected from the field populations of external galaxies. A stacking analysis of the individually undetected UCDs/ESCs further reveals significant X-ray signals, which corresponds to an equivalent 0.5–8 keV luminosity of ∼4 × 10 35 erg s −1 per source. Taken together, these provide strong evidence that the X-ray emission from UCDs and ESCs is dominated by low-mass X-ray binaries having formed from stellar dynamical interactions, consistent with the stellar populations in these dense systems being predominantly old. For the most massive UCDs, there remains the possibility that a putative central massive black hole gives rise to the observed X-ray emission

CHANDRA DETECTION OF X-RAY EMISSION FROM ULTRACOMPACT DWARF GALAXIES AND EXTENDED STAR CLUSTERS

Energy Technology Data Exchange (ETDEWEB)

Hou, Meicun; Li, Zhiyuan, E-mail: lizy@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210046 (China)

2016-03-10

We have conducted a systematic study of X-ray emission from ultracompact dwarf (UCD) galaxies and extended star clusters (ESCs), based on archival Chandra observations. Among a sample of 511 UCDs and ESCs complied from the literature, 17 X-ray counterparts with 0.5–8 keV luminosities above ∼5 × 10{sup 36} erg s{sup −1} are identified, which are distributed in eight early-type host galaxies. To facilitate comparison, we also identify X-ray counterparts of 360 globular clusters (GCs) distributed in four of the eight galaxies. The X-ray properties of the UCDs and ESCs are found to be broadly similar to those of the GCs. The incidence rate of X-ray-detected UCDs and ESCs, 3.3% ± 0.8%, while lower than that of the X-ray-detected GCs (7.0% ± 0.4%), is substantially higher than expected from the field populations of external galaxies. A stacking analysis of the individually undetected UCDs/ESCs further reveals significant X-ray signals, which corresponds to an equivalent 0.5–8 keV luminosity of ∼4 × 10{sup 35} erg s{sup −1} per source. Taken together, these provide strong evidence that the X-ray emission from UCDs and ESCs is dominated by low-mass X-ray binaries having formed from stellar dynamical interactions, consistent with the stellar populations in these dense systems being predominantly old. For the most massive UCDs, there remains the possibility that a putative central massive black hole gives rise to the observed X-ray emission.

Technology Requirements for a Square Meter, Arcsecond Resolution Telescope for X-Rays: The SMART-X Mission

Science.gov (United States)

Schwartz, Daniel A.; Allured, Ryan; Bookbinder, Jay A.; Cotroneo, Vincenzo; Forman, William R.; Freeman, Mark D.; McMuldroch, Stuart; Reid, Paul B.; Tananbaum, Harvey; Vikhlinin, Alexey A.;

Atomic Physics Measurements in Support of X-ray Astronomy

Science.gov (United States)

Beiersdorfer, Peter; Brown, G. V.; Kelley, R. E.; Kilbourne, C. A.; Leutenegger, M.; Porter, F. S.; Obst, M.; Lepson, J. K.; Desai, P.; Gu, M. F.

2010-10-01

X-ray astronomy has been a voracious consumer of atomic data, especially after the launch of the Chandra and XMM-Newton X-ray Observatories, which have produced very high-resolution grating spectra of point sources. One of the important issues has been to understand the physics underlying the Fe L-shell spectra, and the Fe XVII spectrum in particular. A lot of progress has been made, including measurements of the electron-impact and resonance excitation cross sections, which now provides a rather clear picture of the production mechanism of the Fe XVII spectrum. Recent measurements of the radiative rates provide additional information on the deexcitation channels, while investigations of dielectronic satellite transitions provide a measure of the electron temperature. Many questions, however, still remain. Work at LLNL was performed under the auspices of DOE under contract DE-AC53-07NA27344 and supported by NASA's APRA program under contracts NNH07AF81I and NNG06WF08I. Part of this work was supported by Chandra Cycle 10 Award AR9-0002X.

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.

Chandra X-ray observations of the hyper-luminous infrared galaxy IRAS F15307+3252

Science.gov (United States)

Hlavacek-Larrondo, J.; Gandhi, P.; Hogan, M. T.; Gendron-Marsolais, M.-L.; Edge, A. C.; Fabian, A. C.; Russell, H. R.; Iwasawa, K.; Mezcua, M.

2017-01-01

Hyper-luminous infrared galaxies (HyLIRGs) lie at the extreme luminosity end of the IR galaxy population with LIR > 1013 L⊙. They are thought to be closer counterparts of the more distant sub-millimeter galaxies, and should therefore be optimal targets to study the most massive systems in formation. We present deep Chandra observations of IRAS F15307+3252 (100 ks), a classical HyLIRG located at z = 0.93 and hosting a radio-loud AGN (L1.4 GHz ˜ 3.5 × 1025 W Hz-1). The Chandra images reveal the presence of extended (r = 160 kpc), asymmetric X-ray emission in the soft 0.3-2.0 keV band that has no radio counterpart. We therefore argue that the emission is of thermal origin originating from a hot intragroup or intracluster medium virializing in the potential. We find that the temperature (˜2 keV) and bolometric X-ray luminosity (˜3 × 1043 erg s-1) of the gas follow the expected LX-ray-T correlation for groups and clusters, and that the gas has a remarkably short cooling time of 1.2 Gyr. In addition, VLA radio observations reveal that the galaxy hosts an unresolved compact steep-spectrum (CSS) source, most likely indicating the presence of a young radio source similar to 3C186. We also confirm that the nucleus is dominated by a redshifted 6.4 keV Fe Kα line, strongly suggesting that the AGN is Compton-thick. Finally, Hubble images reveal an overdensity of galaxies and sub-structure in the galaxy that correlates with soft X-ray emission. This could be a snapshot view of on-going groupings expected in a growing cluster environment. IRAS F15307+3252 might therefore be a rare example of a group in the process of transforming into a cluster.

Stellar Forensics with Striking Image from Chandra

Science.gov (United States)

2007-10-01

A spectacular new image shows how complex a star's afterlife can be. By studying the details of this image made from a long observation by NASA's Chandra X-ray Observatory, astronomers can better understand how some stars die and disperse elements like oxygen into the next generation of stars and planets. At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. The image shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen, other elements such as neon and silicon that were forged in the star before it exploded. Hard X-ray Image of G292.0+1.8 Hard X-ray Image of G292.0+1.8 "We are finding that, just like snowflakes, each supernova remnant is complicated and beautiful in its own way," said Sangwook Park of Penn State who led the work, released in conjunction with the "8 Years of Chandra" symposium in Huntsville, Ala. The new, deep Chandra image - equaling nearly 6 days worth of observing time - shows an incredibly complex structure. Understanding the details of G292.0+1.8 is especially important because astronomers have considered it to be a "textbook" case of a supernova created by the death of a massive star. Chandra X-ray Image of G292.0+1.8 Chandra X-ray Image of G292.0+1.8 By mapping the distribution of X-rays in different energy bands, the Chandra image traces the distribution of chemical elements ejected in the supernova. The results imply that the explosion was not symmetrical. For example, blue (silicon and sulfur) and green (magnesium) are seen strongly in the upper right, while yellow and orange (oxygen) dominate the lower left. These elements light up at different temperatures, indicating that the temperature is higher in the upper right portion of G292.0+1.8. Slightly below and to the left of the center of G292.0+1.8 is a pulsar, a dense, rapidly rotating neutron star that remained behind after the original star

A high spatial resolution X-ray and Hα study of hot gas in the halos of star-forming disk galaxies -- testing feedback models

Science.gov (United States)

Strickland, D. K.; Heckman, T. M.; Colbert, E. J. M.; Hoopes, C. G.; Weaver, K. A.

2002-12-01

We present arcsecond resolution Chandra X-ray and ground-based optical Hα imaging of a sample of ten edge-on star-forming disk galaxies (seven starburst and three ``normal'' spiral galaxies), a sample which covers the full range of star-formation intensity found in disk galaxies. The X-ray observations make use of the unprecented spatial resolution of the Chandra X-ray observatory to robustly remove X-ray emission from point sources, and hence obtain the X-ray properties of the diffuse thermal emission alone. This data has been combined with existing, comparable-resolution, ground-based Hα imaging. We compare these empirically-derived diffuse X-ray properties with various models for the generation of hot gas in the halos of star-forming galaxies: supernova feedback-based models (starburst-driven winds, galactic fountains), cosmologically-motivated accretion of the IGM and AGN-driven winds. SN feedback models best explain the observed diffuse X-ray emission. We then use the data to test basic, but fundamental, aspects of wind and fountain theories, e.g. the critical energy required for disk "break-out." DKS is supported by NASA through Chandra Postdoctoral Fellowship Award Number PF0-10012.

NASA's Chandra Finds Black Holes Are "Green"

Science.gov (United States)

2006-04-01

Black holes are the most fuel efficient engines in the Universe, according to a new study using NASA's Chandra X-ray Observatory. By making the first direct estimate of how efficient or "green" black holes are, this work gives insight into how black holes generate energy and affect their environment. The new Chandra finding shows that most of the energy released by matter falling toward a supermassive black hole is in the form of high-energy jets traveling at near the speed of light away from the black hole. This is an important step in understanding how such jets can be launched from magnetized disks of gas near the event horizon of a black hole. Illustration of Fuel for a Black Hole Engine Illustration of Fuel for a Black Hole Engine "Just as with cars, it's critical to know the fuel efficiency of black holes," said lead author Steve Allen of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University, and the Stanford Linear Accelerator Center. "Without this information, we cannot figure out what is going on under the hood, so to speak, or what the engine can do." Allen and his team used Chandra to study nine supermassive black holes at the centers of elliptical galaxies. These black holes are relatively old and generate much less radiation than quasars, rapidly growing supermassive black holes seen in the early Universe. The surprise came when the Chandra results showed that these "quiet" black holes are all producing much more energy in jets of high-energy particles than in visible light or X-rays. These jets create huge bubbles, or cavities, in the hot gas in the galaxies. Animation of Black Hole in Elliptical Galaxy Animation of Black Hole in Elliptical Galaxy The efficiency of the black hole energy-production was calculated in two steps: first Chandra images of the inner regions of the galaxies were used to estimate how much fuel is available for the black hole; then Chandra images were used to estimate the power required to produce

Chandra Source Catalog: Background Determination and Source Detection

Science.gov (United States)

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

2009-01-01

The Chandra Source Catalog (CSC) is a major project in which all of the pointed imaging observations taken by the Chandra X-Ray Observatory will used to generate the most extensive X-ray source catalog produced to date. Early in the development of the CSC it was recognized that the ability to estimate local background levels in an automated fashion would be critical for essential CSC tasks such as source detection, photometry, sensitivity estimates, and source characterization. We present a discussion of how such background maps are created directly from the Chandra data and how they are used in source detection. The general background for Chandra observations is rather smoothly varying, containing only low spatial frequency components. However, in the case of ACIS data, a high spatial frequency component is added that is due to the readout streaks of the CCD chips. We discuss how these components can be estimated reliably using the Chandra data and what limitations and caveats should be considered in their use. We will discuss the source detection algorithm used for the CSC and the effects of the background images on the detection results. We will also touch on some the Catalog Inclusion and Quality Assurance criteria applied to the source detection results. This work is supported by NASA contract NAS8-03060 (CXC).

Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

Science.gov (United States)

Weisskopf, Martin C.; Hester, J. Jeff; Tennant, Allyn F.; Elsner, Ronald F.; Schulz, Norbert S.; Marshall, Herman L.; Karovska, Margarita; Nichols, Joy S.; Swartz, Douglas A.; Kolodziejczak, Jeffery J.

2000-01-01

The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced Charge Coupled Devices (CCD) Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula.

Science.gov (United States)

Weisskopf; Hester; Tennant; Elsner; Schulz; Marshall; Karovska; Nichols; Swartz; Kolodziejczak; O'Dell

2000-06-20

The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

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.

ON NEUTRAL ABSORPTION AND SPECTRAL EVOLUTION IN X-RAY BINARIES

International Nuclear Information System (INIS)

Miller, J. M.; Cackett, E. M.; Reis, R. C.

2009-01-01

Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low-energy portion of the spectrum should be attributed to evolution in the source, or instead to evolution in neutral photoelectric absorption. Dispersive spectrometers make it possible to address this problem. We have analyzed a small but diverse set of X-ray binaries observed with the Chandra High Energy Transmission Grating Spectrometer across a range in luminosity and different spectral states. The column density in individual photoelectric absorption edges remains constant with luminosity, both within and across source spectral states. This finding suggests that absorption in the interstellar medium strongly dominates the neutral column density observed in spectra of X-ray binaries. Consequently, evolution in the low-energy spectrum of X-ray binaries should properly be attributed to evolution in the source spectrum. We discuss our results in the context of X-ray binary spectroscopy with current and future X-ray missions.

Spectacular X-ray Jet Points Toward Cosmic Energy Booster

Science.gov (United States)

2000-06-01

NASA's Chandra X-ray Observatory has revealed a spectacular luminous spike of X rays that emanates from the vicinity of a giant black hole in the center of the radio galaxy Pictor A. The spike, or jet, is due to a beam of particles that streaks across hundreds of thousands of light years of intergalactic space toward a brilliant X-ray hot spot that marks its end point. Pictor A Image Press Image and Caption The hot spot is at least 800 thousand light years (8 times the diameter of our Milky Way galaxy) away from where the jet originates. It is thought to represent the advancing head of the jet, which brightens conspicuously where it plows into the tenuous gas of intergalactic space. The jet, powered by the giant black hole, originates from a region of space no bigger than the solar system. "Both the brightness and the spectrum of the X rays are very different from what theory predicts," Professor Andrew Wilson reported today at the 196th national meeting of the American Astronomical Society in Rochester, New York. Wilson, of the University of Maryland, College Park, along with Dr. Patrick Shopbell and Dr. Andrew Young, also of the University of Maryland, are submitting an article on this research to the Astrophysical Journal. "The Chandra observations are telling us that something out there is producing many more high-energy particles than we expected," said Wilson. One possible explanation for the X rays is that shock waves along the side and head of the X-ray jet are accelerating electrons and possibly protons to speeds close to that of light. In the process the electrons are boosted to energies as high as 100 million times their own rest mass energy. These electrons lose their energy rapidly as they produce X rays, so this could be the first direct evidence of this process so far outside a galaxy. The hot spot has been seen with optical and radio telescopes. Radio telescopes have also observed a faint jet. Jets are thought to be produced by the extreme

The Chandra Source Catalog: Background Determination and Source Detection

Science.gov (United States)

McCollough, Michael; Rots, Arnold; Primini, Francis A.; Evans, Ian N.; Glotfelty, Kenny J.; Hain, Roger; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Davis, John E.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Danny G. Gibbs, II; Grier, John D.; Hall, Diane M.; Harbo, Peter N.; He, Xiang Qun (Helen); Houck, John C.; Karovska, Margarita; Kashyap, Vinay L.; Lauer, Jennifer; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph B.; Mitschang, Arik W.; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Nowak, Michael A.; Plummer, David A.; Refsdal, Brian L.; Siemiginowska, Aneta L.; Sundheim, Beth A.; Tibbetts, Michael S.; van Stone, David W.; Winkelman, Sherry L.; Zografou, Panagoula

2009-09-01

The Chandra Source Catalog (CSC) is a major project in which all of the pointed imaging observations taken by the Chandra X-Ray Observatory are used to generate one of the most extensive X-ray source catalog produced to date. Early in the development of the CSC it was recognized that the ability to estimate local background levels in an automated fashion would be critical for essential CSC tasks such as source detection, photometry, sensitivity estimates, and source characterization. We present a discussion of how such background maps are created directly from the Chandra data and how they are used in source detection. The general background for Chandra observations is rather smoothly varying, containing only low spatial frequency components. However, in the case of ACIS data, a high spatial frequency component is added that is due to the readout streaks of the CCD chips. We discuss how these components can be estimated reliably using the Chandra data and what limitations and caveats should be considered in their use. We will discuss the source detection algorithm used for the CSC and the effects of the background images on the detection results. We will also touch on some the Catalog Inclusion and Quality Assurance criteria applied to the source detection results. This work is supported by NASA contract NAS8-03060 (CXC).

Chandra ACIS-S imaging spectroscopy of anomalously faint X-ray emission from Comet 103P/Hartley 2 during the EPOXI encounter

Science.gov (United States)

Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Dennerl, K.; Bodewits, D.; Combi, M. R.; Lepri, S. T.; Zurbuchen, T. H.; Li, J. Y.; Dello-Russo, N.; Belton, M. J. S.; Knight, M. M.

2013-02-01

We present results from the Chandra X-ray Observatory's characterization of the X-ray emission from Comet 103P/Hartley 2, in support of NASA's Deep Impact Extended close flyby of the comet on 04 November 2010. The comet was observed 4 times for a total on target time of ˜60 ks between the 17th of October and 16th of November 2010, with two of the visits occurring during the EPOXI close approach on 04 November and 05 November 2010. X-ray emission from 103P was qualitatively similar to that observed for collisionally thin Comets 2P/Encke (Lisse, C.M. et al. [2005]. Astrophys. J. 635, 1329-1347) and 9P/Tempel 1 (Lisse, C.M. et al. [2007]. Icarus 190, 391-405). Emission morphology offset sunward but asymmetrical from the nucleus and emission lines produced by charge exchange between highly stripped C, N, and O solar wind minor ions and coma neutral gas species were found. The comet was very under-luminous in the X-ray at all times, representing the 3rd faintest comet ever detected (LX = 1.1 ± 0.3 × 1014 erg s-1). The coma was collisionally thin to the solar wind at all times, allowing solar wind ions to flow into the inner coma and interact with the densest neutral coma gas. Localization of the X-ray emission in the regions of the major rotating gas jets was observed, consistent with the major source of cometary neutral gas species being icy coma dust particles. Variable spectral features due to changing solar wind flux densities and charge states were also seen. Modeling of the Chandra observations from the first three visits using observed gas production rates and ACE solar wind ion fluxes with a charge exchange mechanism for the emission is consistent with the temporal and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma. The X-ray emission during the 4th visit on 16 November 2010 is similar to the unusual behavior seen for Comet 17P/Holmes in 2007 (Christian, D.J. et

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.

X-ray studies of quasars with the Einstein observatory. II

International Nuclear Information System (INIS)

Zamorani, G.; Henry, J.P.; Maccacaro, T.; Tananbaum, H.; Soltan, A.; Avni, Y.; Liebert, J.; Stocke, J.; Strittmatter, P.A.; Weymann, R.J.; Smith, M.G.; Condon, J.J.

1981-01-01

Using the Einstein Observatory, we have carried out X-ray observations of 107 quasars and have detected 79. From the analysis of this sample of objects we find a correlation between optical emission and X-ray emission. Our data for radio-loud quasars also show a correlation between radio emission and X-ray emission. For a given optical luminosity, the average X-ray emission of radio-loud quasars is approx.3 times higher than that of ratio-quiet quasars. In addition, our data suggest that the radio of X-ray to optical luminosity is decreasing with increasing redshift and/or optical luminosity. Taking into account the differences in X-ray luminosity between radio-loud and radio-quiet quasars, and between low-redshift and high-redshift quasars, we estimate that approx.30% of the observed X-ray background is contributed by quasars brighter than m/sub B/roughly-equal20, while much of the remainder can be contributed by still fainter quasars. Our data also imply that the optical log N--m/sub B/ relation for quasars cannot be extrapolated much beyond m/sub B/roughly-equal20 with the steep slope used to characterize optical source counts at brighter magnitudes. This situation supports the picture in which luminosity evolution, rather than pure density evolution, describes the quasar behavior as a function of redshift. We briefly discuss the observed correlation of X-ray luminosity with radio luminosity in the context of current quasar models

The LOFT (Large Observatory for X-ray Timing) background simulations

DEFF Research Database (Denmark)

Campana, R.; Feroci, M.; Del Monte, E.

2012-01-01

The Large Observatory For X-ray Timing (LOFT) is an innovative medium-class mission selected for an assessment phase in the framework of the ESA M3 Cosmic Vision call. LOFT is intended to answer fundamental questions about the behavior of matter in theh very strong gravitational and magnetic fields...

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

NASA's Great Observatories Celebrate the International Year of Astronomy With a National Unveiling of Spectacular Images

Science.gov (United States)

2009-02-01

In 1609, Galileo first turned his telescope to the heavens and gave birth to modern astronomy. To commemorate four hundred years of exploring the universe, 2009 is designated the International Year of Astronomy. NASA's Great Observatories - the Hubble Space Telescope, Spitzer Space Telescope, and Chandra X-ray Observatory - are marking the occasion with the release of a suite of images at over 100 planetariums, museums, nature centers, and schools across the country in conjunction with Galileo's birthday on February 15. The selected sites will unveil a large 9-square-foot print of the spiral galaxy Messier 101 that combines the optical view of Hubble, the infrared view of Spitzer, and the X-ray view of Chandra into one multi-wavelength picture. "It's like using your eyes, night vision goggles, and X-ray vision all at the same time," says Dr. Hashima Hasan, lead scientist for the International Year of Astronomy at NASA Headquarters in Washington. Cas A animation Chandra X-ray Image of M101 Participating institutions also will display a matched trio of Hubble, Spitzer, and Chandra images of Messier 101. Each image shows a different wavelength view of the galaxy that illustrates not only the different science uncovered by each observatory, but also just how far astronomy has come since Galileo. Messier 101 is a face-on spiral galaxy about 22 million light-years away in the constellation Ursa Major. It is in many ways similar to, but larger than, our own Milky Way galaxy. Hubble's visible light view shows off the swirls of bright stars and glowing gas that give the galaxy its nickname the Pinwheel Galaxy. In contrast, Spitzer's infrared-light image sees into the spiral arms and reveals the glow of dust lanes where dense clouds can collapse to form new stars. Chandra's X-ray picture uncovers the high-energy features in the galaxy, such as remnants of exploded stars or matter zooming around black holes. The juxtaposition of observations from these three telescopes

X-ray Outburst in Mira A

OpenAIRE

Karovska, M.; Schlegel, E.; Hack, W.; Wood, B.

2005-01-01

We report here the Chandra ACIS-S detection of a bright soft X-ray transient in the Mira AB interacting symbiotic-like binary. We resolved the system for the first time in the X-rays. Using Chandra and HST images we determined that the unprecedented outburst is likely associated with the cool AGB star (Mira A), the prototype of Mira-type variables. X-rays have never before been detected from an AGB star, and the recent activity signals that the system is undergoing dramatic changes. The total...

Solar and Stellar X-ray Cycles

Science.gov (United States)

Martens, P. C. H.; SADE Team

2004-05-01

Stern et al. have shown that Yohkoh-SXT full disk X-ray irradiance shows an 11 year cycle with an max/min amplitude ratio of a factor 30. Similar cyclic X-ray variation in Sun-like stars observed by ROSAT and its predecessors is observed in only a few cases and limited to a factor two or three. We will show, by means of detailed bandpass comparisons, that this discrepancy cannot be ascribed to the differences in energy response between SXT and the stellar soft X-ray detectors. Is the Sun exceptional? After centuries of geocentric and heliocentric worldviews we find this a difficult proposition to entertain. But perhaps the Sun is a member of a small class of late-type stars with large amplitudes in their X-ray cycles. The stellar X-ray observations listed in the HEASARC catalog are too sparse to verify this hypothesis. To resolve these and related questions we have proposed a small low-cost stellar X-ray spectroscopic imager originally called SADE to obtain regular time series from late and early-type stars and accretion disks. This instrument is complimentary to the much more advanced Chandra and XMM-Newton observatories, and allows them to focus on those sources that require their full spatial and spectral resolution. We will describe the basic design and spectroscopic capability of SADE and show it meets the mission requirements.

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

X-ray Fluorescence Spectroscopy: the Potential of Astrophysics-developed Techniques

Science.gov (United States)

Elvis, M.; Allen, B.; Hong, J.; Grindlay, J.; Kraft, R.; Binzel, R. P.; Masterton, R.

2012-12-01

X-ray fluorescence from the surface of airless bodies has been studied since the Apollo X-ray fluorescence experiment mapped parts of the lunar surface in 1971-1972. That experiment used a collimated proportional counter with a resolving power of ~1 and a beam size of ~1degree. Filters separated only Mg, Al and SI lines. We review progress in X-ray detectors and imaging for astrophysics and show how these advances enable much more powerful use of X-ray fluorescence for the study of airless bodies. Astrophysics X-ray instrumentation has developed enormously since 1972. Low noise, high quantum efficiency, X-ray CCDs have flown on ASCA, XMM-Newton, the Chandra X-ray Observatory, Swift and Suzaku, and are the workhorses of X-ray astronomy. They normally span 0.5 to ~8 keV with an energy resolution of ~100 eV. New developments in silicon based detectors, especially individual pixel addressable devices, such as CMOS detectors, can withstand many orders of magnitude more radiation than conventional CCDs before degradation. The capability of high read rates provides dynamic range and temporal resolution. Additionally, the rapid read rates minimize shot noise from thermal dark current and optical light. CMOS detectors can therefore run at warmer temperatures and with ultra-thin optical blocking filters. Thin OBFs mean near unity quantum efficiency below 1 keV, thus maximizing response at the C and O lines.such as CMOS detectors, promise advances. X-ray imaging has advanced similarly far. Two types of imager are now available: specular reflection and coded apertures. X-ray mirrors have been flown on the Einstein Observatory, XMM-Newton, Chandra and others. However, as X-ray reflection only occurs at small (~1degree) incidence angles, which then requires long focal lengths (meters), mirrors are not usually practical for planetary missions. Moreover the field of view of X-ray mirrors is comparable to the incident angle, so can only image relatively small regions. More useful

Lightweight and High-Resolution Single Crystal Silicon Optics for X-ray Astronomy

Science.gov (United States)

Zhang, William W.; Biskach, Michael P.; Chan, Kai-Wing; Mazzarella, James R.; McClelland, Ryan S.; Riveros, Raul E.; Saha, Timo T.; Solly, Peter M.

2016-01-01

We describe an approach to building mirror assemblies for next generation X-ray telescopes. It incorporates knowledge and lessons learned from building existing telescopes, including Chandra, XMM-Newton, Suzaku, and NuSTAR, as well as from our direct experience of the last 15 years developing mirror technology for the Constellation-X and International X-ray Observatory mission concepts. This approach combines single crystal silicon and precision polishing, thus has the potential of achieving the highest possible angular resolution with the least possible mass. Moreover, it is simple, consisting of several technical elements that can be developed independently in parallel. Lastly, it is highly amenable to mass production, therefore enabling the making of telescopes of very large photon collecting areas.

TGCat : THE CHANDRA TRANSMISSION GRATING DATA CATALOG AND ARCHIVE

International Nuclear Information System (INIS)

Huenemoerder, David P.; Dewey, Daniel; Nowak, Michael A.; Schulz, Norbert S.; Davis, John E.; Houck, John C.; Marshall, Herman L.; Noble, Michael S.; Canizares, Claude R.; Mitschang, Arik; Nichols, Joy S.; Morgan, Doug

2011-01-01

The Chandra Transmission Grating Data Archive and Catalog (TGCat) provides easy access to analysis-ready products, specifically, high-resolution X-ray count spectra and their corresponding calibrations. The web interface makes it easy to find observations of a particular object, type of object, or type of observation; to quickly assess the quality and potential usefulness of the spectra from pre-computed summary plots; or to customize a view with an interactive plotter, optionally combining spectra over multiple orders or observations. Data and responses can be downloaded as a package or as individual files, and the query results themselves can be retrieved as ASCII or Virtual Observatory tables. Portable reprocessing scripts used to create the archive and which use the Chandra X-ray Center's (CXC's) software and other publicly available software are also available, facilitating standard or customized reprocessing from Level 1 CXC archival data to spectra and responses with minimal user interaction.

Chandra Observations of M31 and their Implications for its ISM

Science.gov (United States)

Primini, F.; Garcia, M.; Murray, S.; Forman, W.; Jones, C.; McClintock, J.

2000-01-01

As part of the Chandra X-ray Observatory's Survey/Monitoring Program of M31, we have been regularly observing the bulge amd inner disk of M31 for nearly 1 year, using both the HRC and ACIS Instruments. We present results from our program th it are of interest to the study of the ISM in M31. In particular, spectral analysis of bright, unresolved x-ray sources in the bulge reveals the presence of significant local x-ray extinction (N(sub H) is about 2 x 10(exp 21)/square cm), and we will attempt to map out this extinction, Further, we find that diffuse emission accounts for a significant fraction of the overall x-ray flux from the bulge. Finally, our search for x-ray counterparts to supernova remnants in M31 yields surprisingly few candidates.

Chandra Adds to Story of the Way We Were

Science.gov (United States)

2003-05-01

Data from NASA's Chandra X-ray Observatory have enabled astronomers to use a new way to determine if a young star is surrounded by a planet-forming disk like our early Sun. These results suggest that disks around young stars can evolve rapidly to form planets, or they can be disrupted by close encounters with other stars. Chandra observed two young star systems, TW Hydrae and HD 98800, both of which are in the TW Hydrae Association, a loose cluster of 10 million-year-old stars. Observations at infrared and other wavelengths have shown that several stars in the TW Hydrae Association are surrounded by disks of dust and gas. At a distance of about 180 light years from Earth, these systems are among the nearest analogs to the early solar nebula from which Earth formed. "X-rays give us an excellent new way to probe the disks around stars," said Joel Kastner of the Rochester Institute of Technology in Rochester, NY during a press conference today in Nashville, Tenn. at a meeting of the American Astronomical Society. "They can tell us whether a disk is very near to its parent star and dumping matter onto it, or whether such activity has ceased to be important. In the latter case, presumably the disk has been assimilated into larger bodies - perhaps planets--or disrupted." TW Hydrae and HD 98800A Chandra 0th Order Image of HD98800 Kastner and his colleagues found examples of each type of behavior in their study. One star, TW Hydrae, namesake of the TW Hydrae Association, exhibited features in its X-ray spectrum that provide strong, new evidence that matter is accreting onto the star from a circumstellar disk. They concluded that matter is guided by the star's magnetic field onto one or more hot spots on the surface of the star. In contrast, Chandra observations of the young multiple star system HD 98800 revealed that its brightest star, HD 98800A, is producing X-rays much as the Sun does, from a hot upper atmosphere or corona. HD 98800 is a complex multiple-star system

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

Constellation X-Ray Observatory Unlocking the Mysteries of Black Holes, Dark Matter and Life Cycles of Matter in the Universe

Science.gov (United States)

Weaver, Kim; Wanjek, Christopher

2004-01-01

This document provides an overview of the Contellation X-Ray Observatory and its mission. The observatory consists of four x-ray telescopes borne on a satellite constellation at the Earth-Sun L2 point.

Observational Trends of Cometary X-ray Emission

Science.gov (United States)

Lisse, C. M.

2001-05-01

The unexpected discovery of x-ray emission from Comet Hyakutake in March 1996 (Lisse et al. 1996) has produced a number of questions about the physical mechanism producing the radiation. The original detection and subsequent observations (Dennerl et al. 1997, Mumma et al. 1997, Krasnopolsky et al. 1998, Owens et al. 1998, Lisse et al. 1999, Lisse et a. 2001, Dennerl et al. 2001) have shown that the very soft (best fit thermal bremsstrahlung model kT = 0.23 keV) emission is due to an interaction between the solar wind and the comet's atmosphere. Using the results from the more than 15 comets detected to date in x-rays, we report on the latest results on cometary x-ray emission. Our emphasis will be on understanding the physical mechanism producing the emission, and using this to determine the nature of the cometary coma and solar wind flux. As-observed morphologies, spectra, and light curves will be discussed. We also report on the status of current cometary observations using the new powerful x-ray observatories Chandra and XMM. This work has been graciously supported by grants from the NASA Planetary Astronomy and Astrophysical Data Programs.

High resolution X-ray spectroscopy from the Einstein Observatory

International Nuclear Information System (INIS)

Winkler, P.F.; Canizares, C.R.; Clark, G.W.; Markert, T.H.; Berg, C.; Jernigan, J.G.; Schattenberg, M.L.; Massachusetts Inst. of Tech., Cambridge

1980-01-01

This paper is devoted to a discussion of some results which we have recently obtained from the fourth of the principal intruments on board the Einstein Observatory: M.I.T.'s Focal Plane Crystal Spectrometer (FPCS). We shall begin whith a few general remarks about X-ray spectroscopy, followed by a brief description of the FPCS instrument. The results we present here deal primarily with supernova remnants (SNRs): Puppis A and Cas A in the Galaxy, and N132D and N63A in the Large Magellanic Cloud. In addition we shall briefly discuss a member of the other class of thermal X-ray source under discussion at present; namely, to report our detection of oxygen emission from the vicinity of M87 in the Virgo Cluster. (orig.)

XMM-Newton X-ray Observatory Guest Observer program (AO-1) at CASA

Science.gov (United States)

Skinner, Stephen L.

2003-01-01

In this research program, we obtained and analyzed X-ray observations of the Wolf-Rayet (WR) star WR 110 (HD 165688) using the XMM-Newton space-based observatory. Radio observations were also obtained using the Very Large Array (VLA) radio telescope located in New Mexico and operated by the Natl. Radio Astronomy Observatory (NRAO). This star was targeted for observations primarily because it is believed to be a single WR star without a companion. Single WR stars are thought to emit X-rays from cool plasma in shocks distributed throughout their powerful stellar winds. However, there has been little observational work done to test this idea since single WR stars are relatively weak X-ray sources and have been difficult to detect with previous generation telescopes. The launch of XMM-Newton provides a new telescope that is much more sensitive than its predecessors, allowing single WR stars to be studied in detail for the first time. X-ray emission was clearly detected from WR 110. Analysis of its spectrum yields a surprising result. Its X-ray emitting plasma is distributed over a range of temperatures and is dominated by relatively cool plasma with a characteristic temperature T is approximately 6 million K. Such plasma can be explained by existing theoretical wind shock models. However, the spectrum also shows hotter plasma whose temperature is uncertain but is thought to be in excess of T approximately 30 million K. The origin of this hotter plasma is yet unknown, but possible mechanisms are identified

Optical and X-ray studies of Compact X-ray Binaries in NGC 5904

Science.gov (United States)

Bhalotia, Vanshree; Beck-Winchatz, Bernhard

2018-06-01

Due to their high stellar densities, globular cluster systems trigger various dynamical interactions, such as the formation of compact X-ray binaries. Stellar collisional frequencies have been correlated to the number of X-ray sources detected in various clusters and we hope to measure this correlation for NGC 5904. Optical fluxes of sources from archival HST images of NGC 5904 have been measured using a DOLPHOT PSF photometry in the UV, optical and near-infrared. We developed a data analysis pipeline to process the fluxes of tens of thousands of objects using awk, python and DOLPHOT. We plot color magnitude diagrams in different photometric bands in order to identify outliers that could be X-ray binaries, since they do not evolve the same way as singular stars. Aligning previously measured astrometric data for X-ray sources in NGC 5904 from Chandra with archival astrometric data from HST will filter out the outlier objects that are not X-ray producing, and provide a sample of compact binary systems that are responsible for X-ray emission in NGC 5904. Furthermore, previously measured X-ray fluxes of NGC 5904 from Chandra have also been used to measure the X-ray to optical flux ratio and identify the types of compact X-ray binaries responsible for the X-ray emissions in NGC 5904. We gratefully acknowledge the support from the Illinois Space Grant Consortium.

Monitoring and Detecting X-ray Transients with the Swift Observatory

Science.gov (United States)

Markwardt, Craig

2002-01-01

Swift is a multi-wavelength observatory specifically designed to detect transients sources in the gamma-ray energy band 15-200 keV. The primary goals of the mission involve gamma ray burst (GRB) astronomy, namely to determine the origin of GRBs and their afterglows, and use bursts to probe the early Universe. However, Swift will also discover new X-ray transient sources, and it will be possible to bring Swift's considerable multi-wavelength capabilities to bear on these sources, and those discovered by other means. The Burst Alert Telescope (BAT) is a coded mask instrument sensitive to 15-200 keV gamma rays, and has a field of view which covers approximately 1/8th of the sky in a single pointing. Over a typical observing day, the almost the entire sky will be observed and monitored for new transient sources. Sources will be detected within several hours of observation. The two narrow field instruments, the X-ray Telescope and Ultra-Violet Optical Telescope, can provide sensitive simultaneous imaging and spectroscopy observations in the optical through soft X-ray bands. The Swift science operations team will entertain requests for targets of opportunity for sources which are astrophysically significant. Swift will be ideally suited for the detection of transients which produce hard X-rays, such as black hole binaries and some neutron star systems.

Observation of X-ray lines from a gamma-ray burst (GRB991216): evidence of moving ejecta from the progenitor.

Science.gov (United States)

Piro, L; Garmire, G; Garcia, M; Stratta, G; Costa, E; Feroci, M; Mészáros, P; Vietri, M; Bradt, H; Frail, D; Frontera, F; Halpern, J; Heise, J; Hurley, K; Kawai, N; Kippen, R M; Marshall, F; Murakami, T; Sokolov, V V; Takeshima, T; Yoshida, A

2000-11-03

We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion.

CHANDRA AND XMM-NEWTON X-RAY OBSERVATIONS OF THE HYPERACTIVE T TAURI STAR RY TAU

Energy Technology Data Exchange (ETDEWEB)

Skinner, Stephen L. [Center for Astrophysics and Space Astronomy (CASA), Univ. of Colorado, Boulder, CO 80309-0389 (United States); Audard, Marc [Dept. of Astronomy, University of Geneva, Ch. d’Ecogia 16, CH-1290 Versoix (Switzerland); Güdel, Manuel, E-mail: stephen.skinner@colorado.edu, E-mail: marc.audard@unige.ch, E-mail: manuel.guedel@univie.ac.at [Dept. of Astrophysics, Univ. of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria)

2016-07-20

We present results of pointed X-ray observations of the accreting jet-driving T Tauri star RY Tau using Chandra and XMM-Newton . We obtained high-resolution grating spectra and excellent-quality CCD spectra and light curves with the objective of identifying the physical mechanisms underlying RY Tau’s bright X-ray emission. Grating spectra reveal numerous emission lines spanning a broad range of temperature superimposed on a hot continuum. The X-ray emission measure distribution is dominated by very hot plasma at T {sub hot} ∼ 50 MK, but higher temperatures were present during flares. A weaker cool plasma component is also present as revealed by low-temperature lines such as O viii. X-ray light curves show complex variability consisting of short-duration (∼hours) superhot flares accompanied by fluorescent Fe emission at 6.4 keV superimposed on a slowly varying (∼one day) component that may be tied to stellar rotation. The hot flaring component is undoubtedly of magnetic (e.g., coronal) origin. Soft- and hard-band light curves undergo similar slow variability implying that at least some of the cool plasma shares a common magnetic origin with the hot plasma. Any contribution to the X-ray emission from cool shocked plasma is small compared to the dominant hot component but production of individual low-temperature lines such as O viii in an accretion shock is not ruled out.

Chandra Captures Venus In A Whole New Light

Science.gov (United States)

2001-11-01

Scientists have captured the first X-ray view of Venus using NASA's Chandra X-ray Observatory. The observations provide new information about the atmosphere of Venus and open a new window for examining Earth's sister planet. Venus in X-rays looks similar to Venus in visible light, but there are important differences. The optically visible Venus is due to the reflection of sunlight and, for the relative positions of Venus, Earth and Sun during these observations, shows a uniform half-crescent that is brightest toward the middle. The X-ray Venus is slightly less than a half-crescent and brighter on the limbs. The differences are due to the processes by which Venus shines in visible and X-ray light. The X-rays from Venus are produced by fluorescence, rather than reflection. Solar X-rays bombard the atmosphere of Venus, knock electrons out of the inner parts of the atoms, and excite the atoms to a higher energy level. The atoms almost immediately return to their lower energy state with the emission of a fluorescent X-ray. A similar process involving ultraviolet light produces the visible light from fluorescent lamps. For Venus, most of the fluorescent X-rays come from oxygen and carbon atoms between 120 and 140 kilometers (74 to 87 miles) above the planet's surface. In contrast, the optical light is reflected from clouds at a height of 50 to 70 kilometers (31 to 43 miles). As a result, Venus' Sun-lit hemisphere appears surrounded by an almost-transparent luminous shell in X-rays. Venus looks brightest at the limb since more luminous material is there. Venus X-ray/Optical Composite of Venus Credit: Xray: NASA/CXC/MPE/K.Dennerl et al., Optical: Konrad Dennerl "This opens up the exciting possibility of using X-ray observations to study regions of the atmosphere of Venus that are difficult to investigate by other means," said Konrad Dennerl of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, leader of an international team of scientists that

From EXOSAT to the High Energy Astrophysics Science Archive (HEASARC): X-ray Astronomy Comes of Age

Science.gov (United States)

White, Nicholas E.

2012-01-01

In May 1983 the European Space Agency launched EXOSAT, its first X-ray astronomy observatory. Even though it lasted only 3 short years, this mission brought not only new capabilities that resulted in unexpected discoveries, but also a pioneering approach to operations and archiving that changed X-ray astronomy from observations led by small instrument teams, to an observatory approach open to the entire community through a guest observer program. The community use of the observatory was supported by a small dedicated team of scientists, the precursor to the data center activities created to support e.g. Chandra and XMM-Newton. The new science capabilities of EX OS AT included a 90 hr highly eccentric high earth orbit that allow unprecedented continuous coverage of sources as well as direct communication with the satellite that allowed real time decisions to respond to unexpected events through targets of opportunity. The advantages of this orbit demonstrated by EXOSAT resulted in Chandra and XMM-Newton selecting similar orbits. The three instruments on board the EXOSAT observatory were complementary, designed to give complete coverage over a wide energy band pass of 0.05-50 keY. An onboard processor could be programmed to give multiple data modes that could be optimized in response to science discoveries: These new capabilities resulted in many new discoveries including the first comprehensive study of AGN variability, new orbital periods in X-ray binaries and cataclysmic variables, new black holes, quasi-periodic oscillations from neutron stars and black holes and broad band X-ray spectroscopy. The EXOSAT team generated a well-organized database accessible worldwide over the nascent internet, allowing remote selection of data products, making samples and undertaking surveys from the data. The HEASARC was established by NASA at Goddard Space Flight Center in 1990 as the repository of NASA X-ray and Gamma-ray data. The proven EXOSAT database system became the core

REVISITING THE SHORT-TERM X-RAY SPECTRAL VARIABILITY OF NGC 4151 WITH CHANDRA

International Nuclear Information System (INIS)

Wang Junfeng; Fabbiano, G.; Elvis, M.; Zezas, A.; Karovska, M.; Risaliti, G.

2010-01-01

We present new X-ray spectral data for the Seyfert 1 nucleus in NGC 4151 observed with Chandra for ∼200 ks. A significant ACIS pileup is present, resulting in a nonlinear count rate variation during the observation. With pileup corrected spectral fitting, we are able to recover the spectral parameters and find consistency with those derived from unpiled events in the ACIS readout streak and outer region from the bright nucleus. The absorption corrected 2-10 keV flux of the nucleus varied between 6 x 10 -11 erg s -1 cm -2 and 10 -10 erg s -1 cm -2 (L 2-10 k eV ∼ 1.3-2.1 x 10 42 erg s -1 ). Similar to earlier Chandra studies of NGC 4151 at a historical low state, the photon indices derived from the same absorbed power-law model are Γ ∼ 0.7-0.9. However, we show that Γ is highly dependent on the adopted spectral models. Fitting the power-law continuum with a Compton reflection component gives Γ ∼ 1.1. By including passage of non-uniform X-ray obscuring clouds, we can reproduce the apparent flat spectral states with Γ ∼ 1.7, typical for Seyfert 1 active galactic nuclei. The same model also fits the hard spectra from previous ASCA 'long look' observation of NGC 4151 in the lowest flux state. The spectral variability during our observation can be interpreted as variations in intrinsic soft continuum flux relative to a Compton reflection component that is from distant cold material and constant on short timescale, or variations of partially covering absorber in the line of sight toward the nucleus. An ionized absorber model with ionization parameter log ξ ∼ 0.8-1.1 can also fit the low-resolution ACIS spectra. If the partial covering model is correct, adopting a black hole mass M BH ∼4.6x10 7 M sun we constrain the distance of the obscuring cloud from the central black hole to be r ∼< 9 lt-day, consistent with the size of the broad emission line region of NGC 4151 from optical reverberation mapping.

TRACING THE LOWEST PROPELLER LINE IN MAGELLANIC HIGH-MASS X-RAY BINARIES

Energy Technology Data Exchange (ETDEWEB)

Christodoulou, Dimitris M.; Laycock, Silas G. T.; Yang, Jun; Fingerman, Samuel, E-mail: dimitris_christodoulou@uml.edu, E-mail: silas_laycock@uml.edu, E-mail: jun_yang@uml.edu, E-mail: fingerman.samuel@gmail.com [Lowell Center for Space Science and Technology, 600 Suffolk Street, Lowell, MA 01854 (United States)

2016-09-20

We have combined the published observations of high-mass X-ray binary (HMXB) pulsars in the Magellanic Clouds with a new processing of the complete archival data sets from the XMM-Newton and Chandra observatories in an attempt to trace the lowest propeller line below which accretion to polar caps is inhibited by the centrifugal force and the pulsations from the most weakly magnetized pulsars cease. Previously published data reveal that some of the faster-spinning pulsars with spin periods of P {sub S} < 12 s, detected at relatively low X-ray luminosities L {sub X} , appear to define such a line in the P {sub S} – L {sub X} diagram, characterized by a magnetic moment of μ = 3 × 10{sup 29} G cm{sup 3}. This value implies the presence of surface magnetic fields of B ≥ 3 × 10{sup 11} G in the compact objects of this class. Only a few quiescent HMXBs are found below the propeller line: LXP4.40 and SXP4.78, for which XMM-Newton and Chandra null detections respectively placed firm upper limits on their X-ray fluxes in deep quiescence; and A0538-66, for which many sub-Eddington detections have never measured any pulsations. On the other hand, the data from the XMM-Newton and Chandra archives show clearly that, during routine observation cycles, several sources have been detected below the propeller line in extremely faint, nonpulsating states that can be understood as the result of weak magnetospheric emission when accretion to the poles is centrifugally stalled or severely diminished. We also pay attention to the anomalous X-ray pulsar CXOU J010043.1-721134 that was reported in HMXB surveys. Its pulsations and locations near and above the propeller line indicate that this pulsar could be accreting from a fossil disk.

Monitoring variable X-ray sources in nearby galaxies

Science.gov (United States)

Kong, A. K. H.

2010-12-01

In the last decade, it has been possible to monitor variable X-ray sources in nearby galaxies. In particular, since the launch of Chandra, M31 has been regularly observed. It is perhaps the only nearby galaxy which is observed by an X-ray telescope regularly throughout operation. With 10 years of observations, the center of M31 has been observed with Chandra for nearly 1 Msec and the X-ray skies of M31 consist of many transients and variables. Furthermore, the X-ray Telescope of Swift has been monitoring several ultraluminous X-ray sources in nearby galaxies regularly. Not only can we detect long-term X-ray variability, we can also find spectral variation as well as possible orbital period. In this talk, I will review some of the important Chandra and Swift monitoring observations of nearby galaxies in the past 10 years. I will also present a "high-definition" movie of M31 and discuss the possibility of detecting luminous transients in M31 with MAXI.

Black Hole Paradox Solved By NASA's Chandra

Science.gov (United States)

2006-06-01

Black holes are lighting up the Universe, and now astronomers may finally know how. New data from NASA's Chandra X-ray Observatory show for the first time that powerful magnetic fields are the key to these brilliant and startling light shows. It is estimated that up to a quarter of the total radiation in the Universe emitted since the Big Bang comes from material falling towards supermassive black holes, including those powering quasars, the brightest known objects. For decades, scientists have struggled to understand how black holes, the darkest objects in the Universe, can be responsible for such prodigious amounts of radiation. Animation of a Black Hole Pulling Matter from Companion Star Animation of a Black Hole Pulling Matter from Companion Star New X-ray data from Chandra give the first clear explanation for what drives this process: magnetic fields. Chandra observed a black hole system in our galaxy, known as GRO J1655-40 (J1655, for short), where a black hole was pulling material from a companion star into a disk. "By intergalactic standards J1655 is in our backyard, so we can use it as a scale model to understand how all black holes work, including the monsters found in quasars," said Jon M. Miller of the University of Michigan, Ann Arbor, whose paper on these results appears in this week's issue of Nature. Gravity alone is not enough to cause gas in a disk around a black hole to lose energy and fall onto the black hole at the rates required by observations. The gas must lose some of its orbital angular momentum, either through friction or a wind, before it can spiral inward. Without such effects, matter could remain in orbit around a black hole for a very long time. Illustration of Magnetic Fields in GRO J1655-40 Illustration of Magnetic Fields in GRO J1655-40 Scientists have long thought that magnetic turbulence could generate friction in a gaseous disk and drive a wind from the disk that carries angular momentum outward allowing the gas to fall inward

High Resolution, Non-Dispersive X-Ray Calorimeter Spectrometers on EBITs and Orbiting Observatories

Science.gov (United States)

Porter, Frederick S.

2010-01-01

X-ray spectroscopy is the primary tool for performing atomic physics with Electron beam ion trap (EBITs). X-ray instruments have generally fallen into two general categories, 1) dispersive instruments with very high spectral resolving powers but limited spectral range, limited count rates, and require an entrance slit, generally, for EBITs, defined by the electron beam itself, and 2) non-dispersive solid-state detectors with much lower spectral resolving powers but that have a broad dynamic range, high count rate ability and do not require a slit. Both of these approaches have compromises that limit the type and efficiency of measurements that can be performed. In 1984 NASA initiated a program to produce a non-dispersive instrument with high spectral resolving power for x-ray astrophysics based on the cryogenic x-ray calorimeter. This program produced the XRS non-dispersive spectrometers on the Astro-E, Astro-E2 (Suzaku) orbiting observatories, the SXS instrument on the Astro-H observatory, and the planned XMS instrument on the International X-ray Observatory. Complimenting these spaceflight programs, a permanent high-resolution x-ray calorimeter spectrometer, the XRS/EBIT, was installed on the LLNL EBIT in 2000. This unique instrument was upgraded to a spectral resolving power of 1000 at 6 keV in 2003 and replaced by a nearly autonomous production-class spectrometer, the EBIT Calorimeter Spectrometer (ECS), in 2007. The ECS spectrometer has a simultaneous bandpass from 0.07 to over 100 keV with a spectral resolving power of 1300 at 6 keV with unit quantum efficiency, and 1900 at 60 keV with a quantum efficiency of 30%. X-ray calorimeters are event based, single photon spectrometers with event time tagging to better than 10 us. We are currently developing a follow-on instrument based on a newer generation of x-ray calorimeters with a spectral resolving power of 3000 at 6 keV, and improved timing and measurement cadence. The unique capabilities of the x-ray

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

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

A Chandra Survey of Milky Way Globular Clusters. I. Emissivity and Abundance of Weak X-Ray Sources

Science.gov (United States)

Cheng, Zhongqun; Li, Zhiyuan; Xu, Xiaojie; Li, Xiangdong

2018-05-01

Based on archival Chandra data, we have carried out an X-ray survey of 69, or nearly half the known population of, Milky Way globular clusters (GCs), focusing on weak X-ray sources, mainly cataclysmic variables (CVs) and coronally active binaries (ABs). Using the cumulative X-ray luminosity per unit stellar mass (i.e., X-ray emissivity) as a proxy of the source abundance, we demonstrate a paucity (lower by 41% ± 27% on average) of weak X-ray sources in most GCs relative to the field, which is represented by the Solar Neighborhood and Local Group dwarf elliptical galaxies. We also revisit the mutual correlations among the cumulative X-ray luminosity (L X), cluster mass (M), and stellar encounter rate (Γ), finding {L}{{X}}\\propto {M}0.74+/- 0.13, {L}{{X}}\\propto {{{Γ }}}0.67+/- 0.07 and {{Γ }}\\propto {M}1.28+/- 0.17. The three quantities can further be expressed as {L}{{X}}\\propto {M}0.64+/- 0.12 {{{Γ }}}0.19+/- 0.07, which indicates that the dynamical formation of CVs and ABs through stellar encounters in GCs is less dominant than previously suggested, and that the primordial formation channel has a substantial contribution. Taking these aspects together, we suggest that a large fraction of primordial, soft binaries have been disrupted in binary–single or binary–binary stellar interactions before they could otherwise evolve into X-ray-emitting close binaries, whereas the same interactions also have led to the formation of new close binaries. No significant correlations between {L}{{X}}/{L}K and cluster properties, including dynamical age, metallicity, and structural parameters, are found.

NASA's Chandra Reveals Origin of Key Cosmic Explosions

Science.gov (United States)

2010-02-01

WASHINGTON -- New findings from NASA's Chandra X-ray Observatory have provided a major advance in understanding a type of supernova critical for studying the dark energy that astronomers think pervades the universe. The results show mergers of two dense stellar remnants are the likely cause of many of the supernovae that have been used to measure the accelerated expansion of the universe. These supernovae, called Type Ia, serve as cosmic mile markers to measure expansion of the universe because they can be seen at large distances, and they follow a reliable pattern of brightness. However, until now, scientists have been unsure what actually causes the explosions. "These are such critical objects in understanding the universe," said Marat Gilfanov of the Max Planck Institute for Astrophysics in Germany and lead author of the study that appears in the Feb. 18 edition of the journal Nature. "It was a major embarrassment that we did not know how they worked. Now we are beginning to understand what lights the fuse of these explosions." Most scientists agree a Type Ia supernova occurs when a white dwarf star -- a collapsed remnant of an elderly star -- exceeds its weight limit, becomes unstable and explodes. Scientists have identified two main possibilities for pushing the white dwarf over the edge: two white dwarfs merging or accretion, a process in which the white dwarf pulls material from a sun-like companion star until it exceeds its weight limit. "Our results suggest the supernovae in the galaxies we studied almost all come from two white dwarfs merging," said co-author Akos Bogdan, also of Max Planck. "This is probably not what many astronomers would expect." The difference between these two scenarios may have implications for how these supernovae can be used as "standard candles" -- objects of a known brightness -- to track vast cosmic distances. Because white dwarfs can come in a range of masses, the merger of two could result in explosions that vary somewhat in

CHANDRA CHARACTERIZATION OF X-RAY EMISSION IN THE YOUNG F-STAR BINARY SYSTEM HD 113766

International Nuclear Information System (INIS)

Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Günther, H. M.; Chen, C. H.; Grady, C. A.

2017-01-01

Using Chandra , we have obtained imaging X-ray spectroscopy of the 10–16 Myr old F-star binary HD 113766. We individually resolve the 1.″4 separation binary components for the first time in the X-ray and find a total 0.3–2.0 keV luminosity of 2.2 × 10 29 erg s −1 , consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only ∼10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or substellar member of HD 113766 with L x  > 6 × 10 25 erg s −1 within 2′ of the binary pair. The ratio of the two stars’ X-ray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. The emission is soft for both stars, kT Apec  = 0.30–0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks, which we rule out. A possible 2.8 ± 0.15 (2 σ ) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and of unknown provenance. Stellar wind drag models corresponding to L x  ∼ 2 × 10 29 erg s −1 argue for a 1 mm dust particle lifetime around HD 113766B of only ∼90,0000 years, suggesting that dust around HD 113766B is quickly removed, whereas 1 mm sized dust around HD 113766A can survive for >1.5 × 10 6 years. At 10 28 –10 29 erg s −1 X-ray luminosity, astrobiologically important effects, like dust warming and X-ray photolytic organic synthesis, are likely for any circumstellar material in the HD 113766 systems.

DETECTING THE WARM-HOT INTERGALACTIC MEDIUM THROUGH X-RAY ABSORPTION LINES

Energy Technology Data Exchange (ETDEWEB)

Yao Yangsen; Shull, J. Michael; Cash, Webster [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Wang, Q. Daniel, E-mail: yaoys@colorado.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

2012-02-20

The warm-hot intergalactic medium (WHIM) at temperatures 10{sup 5}-10{sup 7} K is believed to contain 30%-50% of the baryons in the local universe. However, all current X-ray detections of the WHIM at redshifts z > 0 are of low statistical significance ({approx}< 3{sigma}) and/or controversial. In this work, we aim to establish the detection limits of current X-ray observatories and explore requirements for next-generation X-ray telescopes for studying the WHIM through X-ray absorption lines. We analyze all available grating observations of Mrk 421 and obtain spectra with signal-to-noise ratios (S/Ns) of {approx}90 and 190 per 50 mA spectral bin from Chandra and XMM-Newton observations, respectively. Although these spectra are two of the best ever collected with Chandra and XMM-Newton, we cannot confirm the two WHIM systems reported by Nicastro et al. in 2005. Our bootstrap simulations indicate that spectra with such high S/N cannot constrain the WHIM with O VII column densities N{sub Ovii}{approx}10{sup 15} cm{sup -2} (corresponding to an equivalent width of 2.5 mA for a Doppler velocity of 50 km s{sup -1}) at {approx}> 3{sigma} significance level. The simulation results also suggest that it would take >60 Ms for Chandra and 140 Ms for XMM-Newton to measure the N{sub Ovii} at {>=}4{sigma} from a spectrum of a background QSO with flux of {approx}0.2 mCrab (1 Crab = 2 Multiplication-Sign 10{sup -8} erg s{sup -1} cm{sup -2} at 0.5-2 keV). Future X-ray spectrographs need to be equipped with spectral resolution R {approx} 4000 and effective area A {>=} 100 cm{sup 2} to accomplish the similar constraints with an exposure time of {approx}2 Ms and would require {approx}11 Ms to survey the 15 QSOs with flux {approx}> 0.2 mCrab along which clear intergalactic O VI absorbers have been detected.

Chandra's X-ray Vision

Indian Academy of Sciences (India)

1999-07-23

Jul 23, 1999 ... CXO is 13.8 metres long and its solar arrays have a wingspan of. 19.5 metres as shown in ... the Universe (for example, coronae of stars, matter ejected from .... The telescope system and the scientific instruments were put through ..... solve the puzzle about the origin of cosmic X-ray background- one of the ...

Young Star Cluster Found Aglow With Mysterious X-Ray Cloud

Science.gov (United States)

2002-12-01

A mysterious cloud of high-energy electrons enveloping a young cluster of stars has been discovered by astronomers using NASA's Chandra X-ray Observatory. These extremely high-energy particles could cause dramatic changes in the chemistry of the disks that will eventually form planets around stars in the cluster. Known as RCW 38, the star cluster covers a region about 5 light years across. It contains thousands of stars formed less than a million years ago and appears to be forming new stars even today. The crowded environment of a star cluster is thought to be conducive to the production of hot gas, but not high-energy particles. Such particles are typically produced by exploding stars, or in the strong magnetic fields around neutron stars or black holes, none of which is evident in RCW 38. "The RCW 38 observation doesn't agree with the conventional picture," said Scott Wolk of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, lead author of an Astrophysical Journal Letters paper describing the Chandra observation. "The data show that somehow extremely high-energy electrons are being produced there, although it is not clear how." RCW 38 RCW 38 X-ray, Radio, Infrared Composite Electrons accelerated to energies of trillions of volts are required to account for the observed X-ray spectrum of the gas cloud surrounding the ensemble of stars, which shows an excess of high-energy X-rays. As these electrons move in the magnetic field that threads the cluster, they produce X-rays. One possible origin for the high-energy electrons is a previously undetected supernova that occurred in the cluster. Although direct evidence for the supernova could have faded away thousands of years ago, a shock wave or a rapidly rotating neutron star produced by the outburst could be acting in concert with stellar winds to produce the high-energy electrons. "Regardless of the origin of the energetic electrons," said Wolk, "their presence would change the chemistry of proto

X-ray reflection in oxygen-rich accretion discs of ultracompact X-ray binaries

DEFF Research Database (Denmark)

Madej, O. K.; Garcia, Jeronimo; Jonker, P. G.

2014-01-01

We present spectroscopic X-ray data of two candidate ultracompact X-ray binaries (UCXBs): 4U 0614+091 and 4U 1543-624. We confirm the presence of a broad O viii Ly alpha reflection line (at a parts per thousand 18 angstrom) using XMM-Newton and Chandra observations obtained in 2012 and 2013. The ...

NASA's Great Observatories Celebrate International Year of Astronomy

Science.gov (United States)

2009-11-01

A never-before-seen view of the turbulent heart of our Milky Way galaxy is being unveiled by NASA on Nov. 10. This event will commemorate the 400 years since Galileo first turned his telescope to the heavens in 1609. In celebration of this International Year of Astronomy, NASA is releasing images of the galactic center region as seen by its Great Observatories to more than 150 planetariums, museums, nature centers, libraries, and schools across the country. The sites will unveil a giant, 6-foot-by-3-foot print of the bustling hub of our galaxy that combines a near-infrared view from the Hubble Space Telescope, an infrared view from the Spitzer Space Telescope, and an X-ray view from the Chandra X-ray Observatory into one multiwavelength picture. Experts from all three observatories carefully assembled the final image from large mosaic photo surveys taken by each telescope. This composite image provides one of the most detailed views ever of our galaxy's mysterious core. Participating institutions also will display a matched trio of Hubble, Spitzer, and Chandra images of the Milky Way's center on a second large panel measuring 3 feet by 4 feet. Each image shows the telescope's different wavelength view of the galactic center region, illustrating not only the unique science each observatory conducts, but also how far astronomy has come since Galileo. The composite image features the spectacle of stellar evolution: from vibrant regions of star birth, to young hot stars, to old cool stars, to seething remnants of stellar death called black holes. This activity occurs against a fiery backdrop in the crowded, hostile environment of the galaxy's core, the center of which is dominated by a supermassive black hole nearly four million times more massive than our Sun. Permeating the region is a diffuse blue haze of X-ray light from gas that has been heated to millions of degrees by outflows from the supermassive black hole as well as by winds from massive stars and by stellar

The radio-X-ray relation as a star formation indicator: results from the Very Large Array-Extended Chandra Deep Field-South

Science.gov (United States)

Vattakunnel, S.; Tozzi, P.; Matteucci, F.; Padovani, P.; Miller, N.; Bonzini, M.; Mainieri, V.; Paolillo, M.; Vincoletto, L.; Brandt, W. N.; Luo, B.; Kellermann, K. I.; Xue, Y. Q.

2012-03-01

In order to trace the instantaneous star formation rate (SFR) at high redshift, and thus help in understanding the relation between the different emission mechanisms related to star formation, we combine the recent 4-Ms Chandra X-ray data and the deep Very Large Array radio data in the Extended Chandra Deep Field-South region. We find 268 sources detected both in the X-ray and radio bands. The availability of redshifts for ˜95 per cent of the sources in our sample allows us to derive reliable luminosity estimates and the intrinsic properties from X-ray analysis for the majority of the objects. With the aim of selecting sources powered by star formation in both bands, we adopt classification criteria based on X-ray and radio data, exploiting the X-ray spectral features and time variability, taking advantage of observations scattered across more than 10 years. We identify 43 objects consistent with being powered by star formation. We also add another 111 and 70 star-forming candidates detected only in the radio and X-ray bands, respectively. We find a clear linear correlation between radio and X-ray luminosity in star-forming galaxies over three orders of magnitude and up to z˜ 1.5. We also measure a significant scatter of the order of 0.4 dex, higher than that observed at low redshift, implying an intrinsic scatter component. The correlation is consistent with that measured locally, and no evolution with redshift is observed. Using a locally calibrated relation between the SFR and the radio luminosity, we investigate the LX(2-10 keV)-SFR relation at high redshift. The comparison of the SFR measured in our sample with some theoretical models for the Milky Way and M31, two typical spiral galaxies, indicates that, with current data, we can trace typical spirals only at z≤ 0.2, and strong starburst galaxies with SFRs as high as ˜100 M⊙ yr-1, up to z˜ 1.5.

Using the Chandra Source-Finding Algorithm to Automatically Identify Solar X-ray Bright Points

Science.gov (United States)

Adams, Mitzi L.; Tennant, A.; Cirtain, J. M.

2009-01-01

This poster details a technique of bright point identification that is used to find sources in Chandra X-ray data. The algorithm, part of a program called LEXTRCT, searches for regions of a given size that are above a minimum signal to noise ratio. The algorithm allows selected pixels to be excluded from the source-finding, thus allowing exclusion of saturated pixels (from flares and/or active regions). For Chandra data the noise is determined by photon counting statistics, whereas solar telescopes typically integrate a flux. Thus the calculated signal-to-noise ratio is incorrect, but we find we can scale the number to get reasonable results. For example, Nakakubo and Hara (1998) find 297 bright points in a September 11, 1996 Yohkoh image; with judicious selection of signal-to-noise ratio, our algorithm finds 300 sources. To further assess the efficacy of the algorithm, we analyze a SOHO/EIT image (195 Angstroms) and compare results with those published in the literature (McIntosh and Gurman, 2005). Finally, we analyze three sets of data from Hinode, representing different parts of the decline to minimum of the solar cycle.

PROBING X-RAY ABSORPTION AND OPTICAL EXTINCTION IN THE INTERSTELLAR MEDIUM USING CHANDRA OBSERVATIONS OF SUPERNOVA REMNANTS

Energy Technology Data Exchange (ETDEWEB)

Foight, Dillon R.; Slane, Patrick O. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Güver, Tolga [Istanbul University, Science Faculty, Department of Astronomy and Space Sciences, Beyazıt, 34119, Istanbul (Turkey); Özel, Feryal [Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

2016-07-20

We present a comprehensive study of interstellar X-ray extinction using the extensive Chandra supernova remnant (SNR) archive and use our results to refine the empirical relation between the hydrogen column density and optical extinction. In our analysis, we make use of the large, uniform data sample to assess various systematic uncertainties in the measurement of the interstellar X-ray absorption. Specifically, we address systematic uncertainties that originate from (i) the emission models used to fit SNR spectra; (ii) the spatial variations within individual remnants; (iii) the physical conditions of the remnant such as composition, temperature, and non-equilibrium regions; and (iv) the model used for the absorption of X-rays in the interstellar medium. Using a Bayesian framework to quantify these systematic uncertainties, and combining the resulting hydrogen column density measurements with the measurements of optical extinction toward the same remnants, we find the empirical relation N {sub H} = (2.87 ± 0.12) × 10{sup 21} A {sub V} cm{sup 2}, which is significantly higher than the previous measurements.

Anti-correlated X-ray and Radio Variability in the Transitional Millisecond Pulsar PSR J1023+0038

Science.gov (United States)

Bogdanov, Slavko; Deller, Adam; Miller-Jones, James; Archibald, Anne; Hessels, Jason W. T.; Jaodand, Amruta; Patruno, Alessandro; Bassa, Cees; D'Angelo, Caroline

2018-01-01

The PSR J1023+0038 binary system hosts a 1.69-ms neutron star and a low-mass, main-sequence-like star. The system underwent a transformation from a rotation-powered to a low-luminosity accreting state in 2013 June, in which it has remained since. We present an unprecedented set of strictly simultaneous Chandra X-ray Observatory and Karl G. Jansky Very Large Array observations, which for the first time reveal a highly reproducible, anti-correlated variability pattern. Rapid declines in X-ray flux are always accompanied by a radio brightening with duration that closely matches the low X-ray flux mode intervals. We discuss these findings in the context of accretion and jet outflow physics and their implications for using the radio/X-ray luminosity plane to distinguish low-luminosity candidate black hole binary systems from accreting transitional millisecond pulsars.

Op. No A4495 Columbia, STS-93 Chandra - Breakfast, Suiting, and Walkout

Science.gov (United States)

1999-01-01

The primary objective of the STS-93 mission was to deploy the Advanced X-ray Astrophysical Facility, which had been renamed the Chandra X-ray Observatory in honor of the late Indian-American Nobel Laureate Subrahmanyan Chandrasekhar. The mission was launched at 12:31 on July 23, 1999 onboard the space shuttle Columbia. The mission was led by Commander Eileen Collins. The crew was Pilot Jeff Ashby and Mission Specialists Cady Coleman, Steve Hawley and Michel Tognini from the Centre National d'Etudes Spatiales (CNES). This videotape shows the astronauts after breakfast getting into spacesuits, walking out to board the bus, and boarding the bus prior to launch.

Einstein Observatory magnitude-limited X-ray survey of late-type giant and supergiant stars

Science.gov (United States)

Maggio, A.; Vaiana, G. S.; Haisch, B. M.; Stern, R. A.; Bookbinder, J.

1990-01-01

Results are presented of an extensive X-ray survey of 380 giant and supergiant stars of spectral types from F to M, carried out with the Einstein Observatory. It was found that the observed F giants or subgiants (slightly evolved stars with a mass M less than about 2 solar masses) are X-ray emitters at the same level of main-sequence stars of similar spectral type. The G giants show a range of emissions more than 3 orders of magnitude wide; some single G giants exist with X-ray luminosities comparable to RS CVn systems, while some nearby large G giants have upper limits on the X-ray emission below typical solar values. The K giants have an observed X-ray emission level significantly lower than F and F giants. None of the 29 M giants were detected, except for one spectroscopic binary.

NuSTAR Hard X-Ray Survey of the Galactic Center Region. II. X-Ray Point Sources

DEFF Research Database (Denmark)

Hong, JaeSub; Mori, Kaya; Hailey, Charles J.

2016-01-01

persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr. A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra...

Assembly of NASA's Most Powerful X-Ray Telescope Completed

Science.gov (United States)

1998-03-01

holes, many of which are invisible to us now. We may even see the processes that create the elements found here on Earth." Assembly of the observatory began in 1997 with the arrival of the high resolution mirror assembly at TRW Space and Electronics Group. In August 1997, the telescope's optical bench was mated with the mirrors, followed by integration of the telescope with the spacecraft in October. In February 1998, the observatory's science instrument module was mated to the top of the telescope. The complete observatory is 45 feet long, has a solar array wing span 64 feet wide, and weighs more than 5 tons. Using glass purchased from Schott Glaswerke, Mainz, Germany, the telescope's mirrors were built by Raytheon Optical Systems Inc., Danbury, Conn. The mirrors were coated by Optical Coating Laboratory Inc., Santa Rosa, Calif.; and assembled by Eastman-Kodak Co., Rochester, N.Y. The observatory's charged coupled device imaging spectrometer was developed by Pennsylvania State University at University Park, and the Massachusetts Institute of Technology (MIT), at Cambridge. One diffraction grating was developed by MIT, the other by the Space Research Organization Netherlands, Utrecht, in collaboration with the Max Planck Institute, Garching, Germany. The high resolution camera instrument was built by the Smithsonian Astrophysical Observatory. Ball Aerospace & Technologies Corporation of Boulder, Colo., developed the science instrument module. The Advanced X-ray Astrophysics Facility program is managed by the Marshall Center for the Office of Space Science, NASA Headquarters, Washington, D.C. The Smithsonian Astrophysical Observatory in Cambridge, Mass., will operate the observatory for NASA. NOTE TO EDITORS: A photo of the integrated telescope is available via the World Wide Web at URL: http://chandra.harvard.edu/press/images.html Prepared by John Bryk

A CHANDRA PERSPECTIVE ON GALAXY-WIDE X-RAY BINARY EMISSION AND ITS CORRELATION WITH STAR FORMATION RATE AND STELLAR MASS: NEW RESULTS FROM LUMINOUS INFRARED GALAXIES

International Nuclear Information System (INIS)

Lehmer, B. D.; Jenkins, L. P.; Alexander, D. M.; Goulding, A. D.; Roberts, T. P.; Bauer, F. E.; Brandt, W. N.; Ptak, A.

2010-01-01

We present new Chandra observations that complete a sample of seventeen (17) luminous infrared galaxies (LIRGs) with D H ∼ 20 cm -2 . The LIRGs in our sample have total infrared (8-1000 μm) luminosities in the range of L IR ∼ (1-8) x 10 11 L sun . The high-resolution imaging and X-ray spectral information from our Chandra observations allow us to measure separately X-ray contributions from active galactic nuclei and normal galaxy processes (e.g., X-ray binaries and hot gas). We utilized total infrared plus UV luminosities to estimate star formation rates (SFRs) and K-band luminosities and optical colors to estimate stellar masses (M * ) for the sample. Under the assumption that the galaxy-wide 2-10 keV luminosity (L gal HX ) traces the combined emission from high-mass X-ray binaries (HMXBs) and low-mass X-ray binaries, and that the power output from these components is linearly correlated with SFR and M * , respectively, we constrain the relation L gal HX = αM * + βSFR. To achieve this, we construct a Chandra-based data set composed of our new LIRG sample combined with additional samples of less actively star-forming normal galaxies and more powerful LIRGs and ultraluminous infrared galaxies (ULIRGs) from the literature. Using these data, we measure best-fit values of α = (9.05 ± 0.37) x 10 28 erg s -1 M -1 sun and β = (1.62 ± 0.22) x 10 39 erg s -1 (M sun yr -1 ) -1 . This scaling provides a more physically meaningful estimate of L gal HX , with ∼0.1-0.2 dex less scatter, than a direct linear scaling with SFR. Our results suggest that HMXBs dominate the galaxy-wide X-ray emission for galaxies with SFR/M * ∼>5.9 x 10 -11 yr -1 , a factor of ∼2.9 times lower than previous estimates. We find that several of the most powerful LIRGs and ULIRGs, with SFR/M * ∼> 10 -9 yr -1 , appear to be X-ray underluminous with respect to our best-fit relation. We argue that these galaxies are likely to contain X-ray binaries residing in compact star-forming regions

CHANDRA CHARACTERIZATION OF X-RAY EMISSION IN THE YOUNG F-STAR BINARY SYSTEM HD 113766

Energy Technology Data Exchange (ETDEWEB)

Lisse, C. M. [Planetary Exploration Branch, Space Exploration Sector, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Christian, D. J. [Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330 (United States); Wolk, S. J. [Chandra X-ray Center, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Günther, H. M. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, NE83-569, Cambridge, MA 02139 (United States); Chen, C. H. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Grady, C. A., E-mail: carey.lisse@jhuapl.edu, E-mail: damian.christian@csun.edu, E-mail: swolk@cfa.harvard.edu, E-mail: hgunther@mit.edu, E-mail: cchen@stsci.edu, E-mail: carol.a.grady@nasa.gov [Eureka Scientific and Goddard Space Flight Center, Code 667, NASA-GSFC, Greenbelt, MD 20771 (United States)

2017-02-01

Using Chandra , we have obtained imaging X-ray spectroscopy of the 10–16 Myr old F-star binary HD 113766. We individually resolve the 1.″4 separation binary components for the first time in the X-ray and find a total 0.3–2.0 keV luminosity of 2.2 × 10{sup 29} erg s{sup −1}, consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only ∼10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or substellar member of HD 113766 with L {sub x} > 6 × 10{sup 25} erg s{sup −1} within 2′ of the binary pair. The ratio of the two stars’ X-ray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. The emission is soft for both stars, kT {sub Apec} = 0.30–0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks, which we rule out. A possible 2.8 ± 0.15 (2 σ ) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and of unknown provenance. Stellar wind drag models corresponding to L {sub x} ∼ 2 × 10{sup 29} erg s{sup −1} argue for a 1 mm dust particle lifetime around HD 113766B of only ∼90,0000 years, suggesting that dust around HD 113766B is quickly removed, whereas 1 mm sized dust around HD 113766A can survive for >1.5 × 10{sup 6} years. At 10{sup 28}–10{sup 29} erg s{sup −1} X-ray luminosity, astrobiologically important effects, like dust warming and X-ray photolytic organic synthesis, are likely for any circumstellar material in the HD 113766 systems.

Examining the X-ray Properties of Lenticular Galaxies: Rollins S0 X-ray Sample (RS0X)

Science.gov (United States)

Fuse, Christopher R.; Malespina, Alysa

2017-01-01

Lenticular galaxies represent a complex morphology in which many questions remain. The S0 morphology possesses spiral galaxy attributes, such as a disk, while also displaying the luminosity and old stellar population indicative of an elliptical galaxy. The proposed formation mechanisms for lenticulars are also varied, with the absence of gas suggesting a faded spiral and the high masses and luminosities implying a merger formation. The star formation and high-energy emission from a sample of S0s will be used to better understand the properties and formation mechanisms of this unique subset of galaxies.We use the Chandra X-ray Observatory archives cycle 1 - 16 to identify a sample of seventeen lenticular galaxies residing in a variety of environments. Data was analyzed using the CIAO software to produce true color images, radial profiles of the halo gas, gas contours, as well as determine the X-ray luminosities of the point sources and gas.The X-ray gas temperature of the sample S0s varied over a narrow range between 0.61 and 0.96 keV, with one outlier, NGC 4382 at 2.0 keV. The X-ray luminosity of the halo gas varies by four dex. The gas temperatures and X-ray luminosities do not vary by environment, with the majority of sample S0s displaying values of typical elliptical galaxies. The S0 sample is X-ray under-luminous relative to the optical luminosity as compared to the sample of early-type galaxies of Ellis & O’Sullivan (2006).The halo gas exhibited some distinct morphological features, such as multiple X-ray peaks, which may indicate a merger event, and highly concentrated gas, suggesting limited gravitational disturbance. Isolated S0, NGC 4406, displays an asymmetric halo, which could be interpreted as gas stripping. An isolated lenticular experiencing gas redistribution due to gravitational perturbation or a cluster-like medium could be interpreted as NGC 4406 forming in a higher galactic density environment than the field.

Chandra Sees Wealth Of Black Holes In Star-Forming Galaxies

Science.gov (United States)

2001-06-01

NASA's Chandra X-ray Observatory has found new populations of suspected mid-mass black holes in several starburst galaxies, where stars form and explode at an unusually high rate. Although a few of these objects had been found previously, this is the first time they have been detected in such large numbers and could help explain their relationship to star formation and the production of even more massive black holes. At the 198th meeting of the American Astronomical Society in Pasadena, California, three independent teams of scientists reported finding dozens of X-ray sources in galaxies aglow with star formation. These X-ray objects appear point-like and are ten to a thousand times more luminous in X-rays than similar sources found in our Milky Way and the M81 galaxy. "Chandra gives us the ability to study the populations of individual bright X-ray sources in nearby galaxies in extraordinary detail," said Andreas Zezas, lead author from the Harvard-Smithsonian Center for Astrophysics team that observed The Antennae, a pair of colliding galaxies, and M82, a well-known starburst galaxy. "This allows us to build on earlier detections of these objects and better understand their relationship to starburst galaxies." Antennae-True Color Image True Color Image of Antennae Credit: NASA/SAO/G.Fabbiano et al. Press Image and Caption Kimberly Weaver, of NASA's Goddard Space Flight Center in Greenbelt, MD, lead scientist of the team that studied the starburst galaxy NGC 253, discussed the importance of the unusual concentration of these very luminous X-ray sources near the center of that galaxy. Four sources, which are tens to thousands of times more massive than the Sun, are located within 3,000 light years of the galaxy core. "This may imply that these black holes are gravitating toward the center of the galaxy where they could coalesce to form a single supermassive black hole," Weaver suggested. "It could be that this starburst galaxy is transforming itself into a quasar

CHANDRA HIGH-ENERGY TRANSMISSION GRATING SPECTRUM OF AE AQUARII

International Nuclear Information System (INIS)

Mauche, Christopher W.

2009-01-01

The nova-like cataclysmic binary AE Aqr, which is currently understood to be a former supersoft X-ray binary and current magnetic propeller, was observed for over two binary orbits (78 ks) in 2005 August with the High-Energy Transmission Grating (HETG) on board the Chandra X-ray Observatory. The long, uninterrupted Chandra observation provides a wealth of details concerning the X-ray emission of AE Aqr, many of which are new and unique to the HETG. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy from σ ∼ 1 eV (510 km s -1 ) for O VIII to σ ∼ 5.5 eV (820 km s -1 ) for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K) = 7.16, has a width σ = 0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d = 100 pc, the total emission measure EM = 8.0 x 10 53 cm -3 and the 0.5-10 keV luminosity L X = 1.1 x 10 31 erg s -1 . Second, based on the f/(i + r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the Heα triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spectrometer spectrum and those of O VII, Ne IX, Mg XI, and Si XIII in the Chandra HETG spectrum, either the electron density of the plasma increases with temperature by over three orders of magnitude, from n e ∼ 6 x 10 10 cm -3 for N VI [log T(K) ∼ 6] to n e ∼ 1 x 10 14 cm -3 for Si XIII [log T(K) ∼ 7], and/or the plasma is significantly affected by photoexcitation. Third, the radial velocity of the X-ray emission lines varies on the white dwarf spin phase, with two oscillations per spin cycle and an amplitude K ∼ 160 km s -1 . These results appear to be inconsistent with the recent models of Itoh et al., Ikhsanov, and

Normal Spiral Galaxies Really Do Have Hot Gas in Their Halos: Chandra Observations of NGC 4013 and NGC 4217.

Science.gov (United States)

Strickland, D. K.; Colbert, E. J. M.; Heckman, T. M.; Hoopes, C. G.; Howk, J. C.; Rand, R. J.

2004-08-01

Although soft X-ray emission from million degree plasma has long been observed in the halos of starburst galaxies known to have supernova-driven galactic superwinds, X-ray observations have generally failed to detect hot halos around normal spiral galaxies. Indeed, the Milky Way and NGC 891 have historically been the only genuinely "normal" spiral galaxies with unambiguous X-ray halo detections, until now. Here we report on deep observations of NGC 4013 and NGC 4217, two Milky-Way-mass spiral galaxies with star formation rates per unit area similar to the Milky Way and NGC 891, using the Chandra X-ray observatory. Preliminary investigation of the observations clearly show extra-planar diffuse X-ray emission extending several kpc into the halo of NGC 4013. We will present the results of these observations, compare them to the non-detections of hot gas around normal spirals, and relate them to galactic fountain and IGM accretion based models for hot halos. DKS acknowledges funding from NASA through the Smithsonian Astrophysical Observatory. grant G045095X.

X-rays Provide a New Way to Investigate Exploding Stars

Science.gov (United States)

2007-05-01

The European Space Agency's X-ray observatory XMM-Newton has revealed a new class of exploding stars - where the X-ray emission 'lives fast and dies young'. The identification of this particular class of explosion gives astronomers a valuable new constraint to help them understand stellar explosions. Exploding stars called novae remain a puzzle to astronomers. "Modelling these outbursts is very difficult," says Wolfgang Pietsch, Max Planck Institut für Extraterrestrische Physik. Now, ESA's XMM-Newton and NASA's Chandra have provided valuable information about when individual novae emit X-rays. Between July 2004 and February 2005, the X-ray observatories watched the heart of the nearby Andromeda Galaxy, known to astronomers as M31. During that time, Pietsch and his colleagues monitored novae, looking for the X-rays. X-ray Image of Andromeda Galaxy (M31) Chandra X-ray Image of Andromeda Galaxy (M31) They detected that eleven out of the 34 novae that had exploded in the galaxy during the previous year were shining X-rays into space. "X-rays are an important window onto novae. They show the atmosphere of the white dwarf," says Pietsch. White dwarfs are hot stellar corpses left behind after the rest of the star has been ejected into space. A typical white dwarf contains about the mass of the Sun, in a spherical volume little bigger than the Earth. It has a strong pull of gravity and, if it is in orbit around a normal star, can rip gas from it. This material builds up on the surface of the white dwarf until it reaches sufficient density to nuclear detonate. The resultant explosion creates a nova. However, these particular events are not strong enough to destroy the underlying white dwarf. The X-ray emission becomes visible some time after the detonation, when the matter ejected by the nova thins out enough to allow astronomers to peer down to the nuclear burning white dwarf atmosphere beneath. At the end of the process, the X-ray emission stops when the fuel is

The Ultracompact Nature of the Black Hole Candidate X-Ray Binary 47 Tuc X9

Science.gov (United States)

Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, J.;

The complete Einstein Observatory X-ray survey of the Orion Nebula region.

Science.gov (United States)

Gagne, Marc; Caillault, Jean-Pierre

1994-01-01

We have analyzed archival Einstein Observatory images of a roughly 4.5 square degree region centered on the Orion Nebula. In all, 245 distinct X-ray sources have been detected in six High Resolution Imager (HRI) and 17 Imaging Proportional Counter (IPC) observations. An optical database of over 2700 stars has been assembled to search for candidate counterparts to the X-ray sources. Roughly half the X-ray sources are identified with a single Orion Nebula cluster member. The 10 main-sequence O6-B5 cluster stars detected in Orion have X-ray activity levels comparable to field O and B stars. X-ray emission has also been detected in the direction of four main-sequence late-B and early-A type stars. Since the mechanisms producing X-rays in late-type coronae and early-type winds cannot operate in the late-B and early-A type atmospheres, we argue that the observed X-rays, with L(sub X) approximately = 3 x 10(exp 30) ergs/s, are probably produced in the coronae of unseen late-type binary companions. Over 100 X-ray sources have been associated with late-type pre-main sequence stars. The upper envelope of X-ray activity rises sharply from mid-F to late-G, with L(sub x)/L(sub bol) in the range 10(exp -4) to 2 x 10(exp -3) for stars later than approximately G7. We have looked for variability of the late-type cluster members on timescales of a day to a year and find that 1/4 of the stars show significantly variable X-ray emission. A handful of the late-type stars have published rotational periods and spectroscopic rotational velocities; however, we see no correlation between X-ray activity and rotation. Thus, for this sample of pre-main-sequence stars, the large dispersion in X-ray activity does not appear to be caused by the dispersion in rotation, in contrast with results obtained for low-mass main-sequence stars in the Pleiades and pre-main-sequence stars in Taurus-Auriga.

X-Ray Scaling Relations of Early-type Galaxies

Science.gov (United States)

Babyk, Iu. V.; McNamara, B. R.; Nulsen, P. E. J.; Hogan, M. T.; Vantyghem, A. N.; Russell, H. R.; Pulido, F. A.; Edge, A. C.

2018-04-01

X-ray luminosity, temperature, gas mass, total mass, and their scaling relations are derived for 94 early-type galaxies (ETGs) using archival Chandra X-ray Observatory observations. Consistent with earlier studies, the scaling relations, L X ∝ T 4.5±0.2, M ∝ T 2.4±0.2, and L X ∝ M 2.8±0.3, are significantly steeper than expected from self-similarity. This steepening indicates that their atmospheres are heated above the level expected from gravitational infall alone. Energetic feedback from nuclear black holes and supernova explosions are likely heating agents. The tight L X –T correlation for low-luminosity systems (i.e., below 1040 erg s‑1) are at variance with hydrodynamical simulations, which generally predict higher temperatures for low-luminosity galaxies. We also investigate the relationship between total mass and pressure, Y X = M g × T, finding M\\propto {Y}X0.45+/- 0.04. We explore the gas mass to total mass fraction in ETGs and find a range of 0.1%–1.0%. We find no correlation between the gas-to-total mass fraction with temperature or total mass. Higher stellar velocity dispersions and higher metallicities are found in hotter, brighter, and more massive atmospheres. X-ray core radii derived from β-model fitting are used to characterize the degree of core and cuspiness of hot atmospheres.

HST/ACS IMAGING OF OMEGA CENTAURI: OPTICAL COUNTERPARTS OF CHANDRA X-RAY SOURCES

International Nuclear Information System (INIS)

Cool, Adrienne M.; Arias, Tersi; Brochmann, Michelle; Dorfman, Jason; Gafford, April; White, Vivian; Haggard, Daryl; Anderson, Jay

2013-01-01

We present results of a search for optical counterparts of X-ray sources in and toward the globular cluster Omega Centauri (NGC 5139) using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The ACS data consist of a mosaic of Wide Field Channel images obtained using F625W, F435W, and F658N filters; with nine pointings we cover the central ∼10' × 10' of the cluster and encompass 109 known Chandra sources. We find promising optical counterparts for 59 of the sources, ∼40 of which are likely to be associated with the cluster. These include 27 candidate cataclysmic variables (CVs), 24 of which are reported here for the first time. Fourteen of the CV candidates are very faint, with absolute magnitudes in the range M 625 =10.4-12.6, making them comparable in brightness to field CVs near the period minimum discovered in the Sloan Digital Sky Survey. Additional optical counterparts include three BY Dra candidates, a possible blue straggler, and a previously reported quiescent low-mass X-ray binary. We also identify 3 foreground stars and 11 probable active galactic nuclei. Finally, we report the discovery of a group of seven stars whose X-ray properties are suggestive of magnetically active binaries, and whose optical counterparts lie on or very near the metal-rich anomalous giant and subgiant branches in ω Cen. If the apparent association between these seven stars and the RGB/SGB-a stars is real, then the frequency of X-ray sources in this metal-rich population is enhanced by a factor of at least five relative to the other giant and subgiant populations in the cluster. If these stars are not members of the metal-rich population, then they bring the total number of red stragglers (also known as sub-subgiants) that have been identified in ω to Cen 20, the largest number yet known in any globular cluster.

HST/ACS Imaging of Omega Centauri: Optical Counterparts of Chandra X-Ray Sources

Science.gov (United States)

Cool, Adrienne M.; Haggard, Daryl; Arias, Tersi; Brochmann, Michelle; Dorfman, Jason; Gafford, April; White, Vivian; Anderson, Jay

2013-02-01

We present results of a search for optical counterparts of X-ray sources in and toward the globular cluster Omega Centauri (NGC 5139) using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The ACS data consist of a mosaic of Wide Field Channel images obtained using F625W, F435W, and F658N filters; with nine pointings we cover the central ~10' × 10' of the cluster and encompass 109 known Chandra sources. We find promising optical counterparts for 59 of the sources, ~40 of which are likely to be associated with the cluster. These include 27 candidate cataclysmic variables (CVs), 24 of which are reported here for the first time. Fourteen of the CV candidates are very faint, with absolute magnitudes in the range M 625 =10.4-12.6, making them comparable in brightness to field CVs near the period minimum discovered in the Sloan Digital Sky Survey. Additional optical counterparts include three BY Dra candidates, a possible blue straggler, and a previously reported quiescent low-mass X-ray binary. We also identify 3 foreground stars and 11 probable active galactic nuclei. Finally, we report the discovery of a group of seven stars whose X-ray properties are suggestive of magnetically active binaries, and whose optical counterparts lie on or very near the metal-rich anomalous giant and subgiant branches in ω Cen. If the apparent association between these seven stars and the RGB/SGB-a stars is real, then the frequency of X-ray sources in this metal-rich population is enhanced by a factor of at least five relative to the other giant and subgiant populations in the cluster. If these stars are not members of the metal-rich population, then they bring the total number of red stragglers (also known as sub-subgiants) that have been identified in ω to Cen 20, the largest number yet known in any globular cluster.

The Advanced X-ray Spectroscopy and Imaging Observatory (AXSIO)

Science.gov (United States)

White, Nicholas E.; Bookbinder, Jay; Petre, Robert; Smith, Randall; Ptak, Andrew; Tananbaum, Harvey; Garcia, Michael

2012-01-01

Following recommendations from the 2010 "New Worlds, New Horizons" (NWNH) report, the Advanced X-ray Spectroscopy and Imaging Observatory (AXSIO) concept streamlines the International X-ray Observatory (IXO) mission to concentrate on the science objectives that are enabled by high-resolution spectroscopic capabilities. AXSIO will trace orbits close to the event horizon of black holes, measure black hole spin for tens of supermassive black holes (SMBH), use spectroscopy to characterize outflows and the environment of AGN during their peak activity, observe 5MBH out to redshift z=6, map bulk motions and turbulence in galaxy clusters, find the missing baryons in the cosmic web using background quasars, and observe the process of cosmic feedback where black holes and supernovae inject energy on galactic and intergalactic scales. These measurements are enabled by a 0.9 sq m collecting area at 1.25 keV, a micro calorimeter array providing high-resolution spectroscopic imaging and a deployable high efficiency grating spectrometer. AXSIO delivers a 30-fold increase in effective area for high resolution spectroscopy. The key simplifications are guided by recommendations in the NWNH panel report include a reduction in focal length from 20m to 10m, eliminating the extendable optical bench, and a reduction in the instrument complement from six to two, avoiding a movable instrument platform. A focus on spectroscopic science allows the spatial resolution requirement to be relaxed to 10 arc sec (with a 5 arc sec goal). These simplifications decrease the total mission cost to under the $2B cost to NASA recommended by NWNH. AXSIO will be available to the entire astronomical community with observing allocations based on peer-review.

X-ray Discovery Points to Location of Missing Matter

Science.gov (United States)

2010-05-01

Using observations with NASA's Chandra X-ray Observatory and ESA's XMM-Newton, astronomers have announced a robust detection of a vast reservoir of intergalactic gas about 400 million light years from Earth. This discovery is the strongest evidence yet that the "missing matter" in the nearby Universe is located in an enormous web of hot, diffuse gas. This missing matter — which is different from dark matter -- is composed of baryons, the particles, such as protons and neutrons, that are found on the Earth, in stars, gas, galaxies, and so on. A variety of measurements of distant gas clouds and galaxies have provided a good estimate of the amount of this "normal matter" present when the universe was only a few billion years old. However, an inventory of the much older, nearby universe has turned up only about half as much normal matter, an embarrassingly large shortfall. The mystery then is where does this missing matter reside in the nearby Universe? This latest work supports predictions that it is mostly found in a web of hot, diffuse gas known as the Warm-Hot Intergalactic Medium (WHIM). Scientists think the WHIM is material left over after the formation of galaxies, which was later enriched by elements blown out of galaxies. "Evidence for the WHIM is really difficult to find because this stuff is so diffuse and easy to see right through," said Taotao Fang of the University of California at Irvine and lead author of the latest study. "This differs from many areas of astronomy where we struggle to see through obscuring material." To look for the WHIM, the researchers examined X-ray observations of a rapidly growing supermassive black hole known as an active galactic nucleus, or AGN. This AGN, which is about two billion light years away, generates immense amounts of X-ray light as it pulls matter inwards. Lying along the line of sight to this AGN, at a distance of about 400 million light years, is the so-called Sculptor Wall. This "wall", which is a large diffuse

Intraday X-Ray Variability of QSOs/AGN Using the Chandra Archives

Science.gov (United States)

Tartamella, C.; Busche, J.

2005-05-01

X-ray variability is a common characteristic of Active Galactic Nuclei (AGN), and it can be used to probe the nuclear region at short time scales. Quantitative analysis of this variability has been difficult due to low signal-to-noise ratios and short time baselines, but serendipitous Chandra data acquired within the last six years have opened the door to such analysis. Cross-correlation of the Chandra archives with QSO/AGN catalogs on NASA's HEASARC website (e.g. Veron, Sloan) yields a sample of 50+ objects that satisfy the following criteria: absolute magnitude M≤ -22.5, proper time baselines greater than 2 hours, and count rates leading to 10% error bars for 8+ flux points on the light curve. The sample includes a range of red-shifts, magnitudes, and type (e.g. radio loud, radio quiet), and hence may yield empirical clues about luminosity or evolutionary trends. As a beginning of such analysis, we present 11 light curves for 9 objects for which the exposure time was greater than 10 hours. The variability was analyzed using three different statistical methods. The Kolmogorov-Smirnov (KS) test proved to be impractical because of the unavoidably small number of data points and the simplistic nature of the test. A χ2 test indicated in most cases that there were significant departures from constant brightness (as expected). Autocorrelation plots were also generated for each light curve. With more work and a larger sample size, these plots can be used to identify any trends in the lightcurve such as whether the variability is stochastic or periodic in nature. This test was useful even with the small number of datapoints available. In future work, more sophisticated analyses based on Fourier series, power density spectra, or wavelets are likely to yield more meaningful and useful results.

Subluminous X-ray binaries

NARCIS (Netherlands)

Armas Padilla, M.

2013-01-01

The discovery of the first X-ray binary, Scorpius X-1, by Giacconi et al. (1962), marked the birth of X-ray astronomy. Following that discovery, many additional X-ray sources where found with the first generation of X-ray rockets and observatories (e.g., UHURU and Einstein). The short-timescale

A Catalog of Candidate Intermediate-Luminosity X-Ray Objects

Science.gov (United States)

Colbert, E. J. M.; Ptak, A. F.

2002-11-01

ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray point sources in galaxies other than our own. X-ray observations of normal galaxies with ROSAT and Chandra have revealed that off-nuclear, compact, intermediate-luminosity (LX[2-10keV]>=1039.0 ergs s-1) X-ray objects (IXOs, a.k.a. ULXs [ultraluminous X-ray sources]) are quite common. Here we present a catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the ROSAT HRI imaging data for galaxies with cz<=5000 km s-1 from the Third Reference Catalog of Bright Galaxies. We have defined the cutoff LX for IXOs so that it is well above the Eddington luminosity of a 1.4 Msolar black hole (1038.3 ergs s-1), so as not to confuse IXOs with ``normal'' black hole X-ray binaries. This catalog is intended to provide a baseline for follow-up work with Chandra and XMM-Newton, and with space- and ground-based survey work at wavelengths other than X-ray. We demonstrate that elliptical galaxies with IXOs have a larger number of IXOs per galaxy than nonelliptical galaxies with IXOs and note that they are not likely to be merely high-mass X-ray binaries with beamed X-ray emission, as may be the case for IXOs in starburst galaxies. Approximately half of the IXOs with multiple observations show X-ray variability, and many (19) of the IXOs have faint optical counterparts in DSS optical B-band images. Follow-up observations of these objects should be helpful in identifying their nature.

X-ray Arcs Tell The Tale Of Giant Eruption

Science.gov (United States)

2002-08-01

Long ago, a giant eruption occurred in a nearby galaxy and plunged it into turmoil. Now NASA's Chandra X-ray Observatory has revealed the remains of that explosion in the form of two enormous arcs of hot gas. This discovery can help astronomers better understand the cause and effect of violent outbursts from the vicinity of supermassive black holes in the centers of many so-called "active" galaxies. Scientists from the Harvard-Smithsonian Center for Astrophysics (CfA) report that two arc-like structures of multimillion-degree gas in the galaxy Centaurus A appear to be part of a ring 25,000 light years in diameter. The size and location of the ring suggest that it could have been produced in a titanic explosion that occurred about ten million years ago. A composite image of the galaxy made with radio (red and green), optical (yellow-orange), and X-ray data (blue) presents a stunning tableau of a tumultuous galaxy. A broad band of dust and cold gas is bisected at an angle by opposing jets of high-energy particles blasting away from the supermassive black hole in the nucleus. Lying in a plane perpendicular to the jets are the two large arcs of X-ray emitting hot gas. "Putting all the images together was the key to understanding what Chandra showed," said Margarita Karovska, lead author on a paper in the September 20, 2002, issue of The Astrophysical Journal. "Suddenly it all clicked in, as with a giant puzzle, and the images fit together to make a complete picture of the galaxy geometry that was not at all apparent before." The team proposes that the orientation of the arcs of hot gas perpendicular to the jet and the symmetry of the projected ring with respect to the center of the galaxy could be evidence that the ring is the result of a giant eruption in the nucleus of the galaxy 10 million years ago. This explosion may have produced a galaxy-sized shock wave that has been moving outward at speeds of a million miles per hour. The age of 10 million years for the

Revisiting the Short-term X-ray Spectral Variability of NGC 4151 with Chandra

Science.gov (United States)

Wang, Junfeng; Risaliti, G.; Fabbiano, G.; Elvis, M.; Zezas, A.; Karovska, M.

2010-05-01

We present new X-ray spectral data for the Seyfert 1 nucleus in NGC 4151 observed with Chandra for ~200 ks. A significant ACIS pileup is present, resulting in a nonlinear count rate variation during the observation. With pileup corrected spectral fitting, we are able to recover the spectral parameters and find consistency with those derived from unpiled events in the ACIS readout streak and outer region from the bright nucleus. The absorption corrected 2-10 keV flux of the nucleus varied between 6 × 10-11 erg s-1 cm-2 and 10-10 erg s-1 cm-2 (L 2-10 keV ~ 1.3-2.1 × 1042 erg s-1). Similar to earlier Chandra studies of NGC 4151 at a historical low state, the photon indices derived from the same absorbed power-law model are Γ ~ 0.7-0.9. However, we show that Γ is highly dependent on the adopted spectral models. Fitting the power-law continuum with a Compton reflection component gives Γ ~ 1.1. By including passage of non-uniform X-ray obscuring clouds, we can reproduce the apparent flat spectral states with Γ ~ 1.7, typical for Seyfert 1 active galactic nuclei. The same model also fits the hard spectra from previous ASCA "long look" observation of NGC 4151 in the lowest flux state. The spectral variability during our observation can be interpreted as variations in intrinsic soft continuum flux relative to a Compton reflection component that is from distant cold material and constant on short timescale, or variations of partially covering absorber in the line of sight toward the nucleus. An ionized absorber model with ionization parameter log ξ ~ 0.8-1.1 can also fit the low-resolution ACIS spectra. If the partial covering model is correct, adopting a black hole mass M_{BH}˜ 4.6× 10^7 M sun we constrain the distance of the obscuring cloud from the central black hole to be r <~ 9 lt-day, consistent with the size of the broad emission line region of NGC 4151 from optical reverberation mapping.

NASA Observatory Confirms Black Hole Limits

Science.gov (United States)

2005-02-01

The very largest black holes reach a certain point and then grow no more, according to the best survey to date of black holes made with NASA's Chandra X-ray Observatory. Scientists have also discovered many previously hidden black holes that are well below their weight limit. These new results corroborate recent theoretical work about how black holes and galaxies grow. The biggest black holes, those with at least 100 million times the mass of the Sun, ate voraciously during the early Universe. Nearly all of them ran out of 'food' billions of years ago and went onto a forced starvation diet. Focus on Black Holes in the Chandra Deep Field North Focus on Black Holes in the Chandra Deep Field North On the other hand, black holes between about 10 and 100 million solar masses followed a more controlled eating plan. Because they took smaller portions of their meals of gas and dust, they continue growing today. "Our data show that some supermassive black holes seem to binge, while others prefer to graze", said Amy Barger of the University of Wisconsin in Madison and the University of Hawaii, lead author of the paper describing the results in the latest issue of The Astronomical Journal (Feb 2005). "We now understand better than ever before how supermassive black holes grow." One revelation is that there is a strong connection between the growth of black holes and the birth of stars. Previously, astronomers had done careful studies of the birthrate of stars in galaxies, but didn't know as much about the black holes at their centers. DSS Optical Image of Lockman Hole DSS Optical Image of Lockman Hole "These galaxies lose material into their central black holes at the same time that they make their stars," said Barger. "So whatever mechanism governs star formation in galaxies also governs black hole growth." Astronomers have made an accurate census of both the biggest, active black holes in the distance, and the relatively smaller, calmer ones closer by. Now, for the first

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

alternative to CSCview, and will present the concept for an additional planned cone-search web-based interface.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.

Localization of the solar flare SF900610 in X-rays with the WATCH instrument of the GRANAT observatory

DEFF Research Database (Denmark)

Terekhov, O.V.; Kuzmin, A.G.; Shevchenko, A.V.

2002-01-01

-ray source do not coincide with the coordinates of the Ha-line flare. The X-ray source moved over the solar disk during the flare. This probably implies that, as the X-ray emission was generated, different parts of one loop or a system of magnetic loops dominated at different flare times.......During the solar flare of June 10, 1990, the WATCH instrument of the GRANAT space observatory obtained 110 localizations of the X-ray source in the X-ray range 8-20 keV. Its coordinates were measured with an accuracy of similar to2 arcmin at a 3sigma confidence level. The coordinates of the X...

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

for the first time. As a follow up to our initial study of its nuclear region, we present the first results concerning the full galaxy from simultaneous NuSTAR, Chandra, and Very Long Baseline Array monitoring of the local starburst galaxy NGC 253. Above ~10 keV, nearly all the emission is concentrated within...... is detected at E > 40 keV. We report upper limits on diffuse inverse Compton emission for a range of spatial models. For the most extended morphologies considered, these hard X-ray constraints disfavor a dominant inverse Compton component to explain the γ-ray emission detected with Fermi and H.E.S.S. If NGC...

From a Sounding Rocket per Year to an Observatory per Lifetime

Science.gov (United States)

Weisskopf, Martin C.

2013-01-01

I attempt to summarize the excitement of my role primarily in the early years of X-ray Astronomy. As a "second generation" X-ray astronomer, I was privileged to participate in the enormous advance of the field, both technically and astrophysically, that took place in the late 1960 s and 1970 s. The remainder of my career has concentrated on the design, construction, calibration, operation, and scientific maintenance of the "cathedral" that is the Chandra X-Ray Observatory. I contrast my early experiences with the current environment for the design and development of instrumentation, especially X-ray optics (which are absolutely essential for the development of the discipline). I express my concerns for the future of X-Ray astronomy and offer specific suggestions that I am hopeful will advance the discipline at a more effective and rapid pace.

X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

Directory of Open Access Journals (Sweden)

Kumiko Morihana

2014-12-01

Full Text Available We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE. We extracted 2,002 X-ray point sources in the Chandra Bulge Field (l =0°.113, b = 1°.424 down to ~10-14.8 ergscm-2s-1 in 2-8 keV band with the longest observation (900 ks of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard, B (soft and broad spectrum, and C (soft and peaked spectrum. In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

Heating the Primordial Soup: X-raying the Circumstellar Disk of T Cha

Science.gov (United States)

Principe, David; Huenemoerder, D.; Kastner, J. H.; Bessell, M. S.; Sacco, G.

2014-01-01

The classical T Tauri Star (cTTS) T Chamaeleontis (T Cha) presents a unique opportunity to probe pre-main sequence star-disk interactions and late-stage circumstellar disk evolution. T Cha is the only known example of a nearly edge-on, actively accreting star/disk system within ~110 pc, and furthermore may be orbited by a low-mass companion or massive planet that has cleared an inner hole in its disk. The star is characterized by strong variability in the optical 3 magnitudes in the V band) as well as large and variable extinction (AV in the range of 1-5). Like most cTTS, T Cha is also a luminous X-ray source. We present preliminary results of two observations (totaling 150 ks) of T Cha with Chandra’s HETGS. Our motivations are to (a) determine the intrinsic X-ray spectrum of T Cha, so as to establish whether its X-ray emission can be attributed to accretion shocks, coronal emission, or a combination; (b) investigate whether its X-ray flux exhibits modulation that may be related to the stellar rotational period 3.3 days); and (c) take advantage of the nearly-edge-on disk viewing geometry to model the spectrum of X-rays absorbed by the gaseous disk orbiting T Cha. These results will serve as much-needed input to models of magnetospheric accretion and irradiated, planet-forming disks. This research is supported via award number GO3-14022X to RIT issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS803060. Additional support is provided by National Science Foundation grant AST-1108950 to RIT.

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

VizieR Online Data Catalog: Intermediate-luminosity X-ray objects catalog (Colbert+, 2002)

Science.gov (United States)

Colbert, E. J. M.; Ptak, A. F.

2002-11-01

ROSAT, and now Chandra, X-ray images allow studies of extranuclear X-ray point sources in galaxies other than our own. X-ray observations of normal galaxies with ROSAT and Chandra have revealed that off-nuclear, compact, intermediate-luminosity (LX[2-10keV]>=1039erg/s) X-ray objects (IXOs, a.k.a. ULXs [ultraluminous X-ray sources]) are quite common. Here we present a catalog and finding charts for 87 IXOs in 54 galaxies, derived from all of the ROSAT HRI imaging data for galaxies with cz<=5000km/s from the Third Reference Catalog of Bright Galaxies. (2 data files).

Giant Rapid X-ray Flares in Extragalactic Globular Clusters

Science.gov (United States)

Irwin, Jimmy

2018-01-01

There is only one known class of non-destructive, highly energetic astrophysical object in the Universe whose energy emission varies by more than a factor of 100 on time scales of less than a minute -- soft gamma repeaters/anomalous X-ray pulsars, whose flares are believed to be caused by the energy release from the cracking of a neutron star's surface by very strong magnetic fields. All other known violent, rapid explosions, including gamma-ray bursts and supernovae, are believed to destroy the object in the process. Here, we report the discovery of a second class of non-destructive, highly energetic rapidly flaring X-ray object located within two nearby galaxies with fundamentally different properties than soft gamma repeaters/anomalous X-ray pulsars. One source is located within a suspected globular cluster of the host galaxy and flared one time, while the other source is located in either a globular cluster of the host galaxy or the core of a stripped dwarf companion galaxy that flared on six occasions over a seven year time span. When not flaring, the sources appear as normal accreting neutron star or black hole X-ray binaries, indicating that the flare event does not significantly disrupt the host system. While the nature of these sources is still unclear, the discovery of these sources in decade-old archival Chandra X-ray Observatory data illustrates the under-utilization of X-ray timing as a means to discover new classes of explosive events in the Universe.

THE X-RAY HALO OF CEN X-3

International Nuclear Information System (INIS)

Thompson, Thomas W. J.; Rothschild, Richard E.

2009-01-01

Using two Chandra observations, we have derived estimates of the dust distribution and distance to the eclipsing high-mass X-ray binary Cen X-3 using the energy-resolved dust-scattered X-ray halo. By comparing the observed X-ray halos in 200 eV bands from 2-5 keV to the halo profiles predicted by the Weingartner and Draine interstellar grain model, we find that the vast majority (∼ 70%) of the dust along the line of sight to the system is located within about 300 pc of the Sun, although the halo measurements are insensitive to dust very close to the source. One of the Chandra observations occurred during an egress from eclipse as the pulsar emerged from behind the mass-donating primary. By comparing model halo light curves during this transition to the halo measurements, a source distance of 5.7 ± 1.5 kpc (68% confidence level) is estimated, although we find this result depends on the distribution of dust on very small scales. Nevertheless, this value is marginally inconsistent with the commonly accepted distance to Cen X-3 of 8 kpc. We also find that the energy scaling of the scattering optical depth predicted by the Weingartner and Draine interstellar grain model does not accurately represent the results determined by X-ray halo studies of Cen X-3. Relative to the model, there appears to be less scattering at low energies or more scattering at high energies in Cen X-3.

CHANDRA DETECTION OF A NEW DIFFUSE X-RAY COMPONENT FROM THE GLOBULAR CLUSTER 47 TUCANAE

Energy Technology Data Exchange (ETDEWEB)

Wu, E. M. H.; Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Hui, C. Y. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Kong, A. K. H.; Tam, P. H. T. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Dogiel, V. A., E-mail: cyhui@cnu.ac.kr [I. E. Tamm Theoretical Physics Division of P. N. Lebedev Institute of Physics, Leninskii pr. 53, 119991 Moscow (Russian Federation)

2014-06-20

In re-analyzing the archival Chandra data of the globular cluster 47 Tucanae, we have detected a new diffuse X-ray emission feature within the half-mass radius of the cluster. The spectrum of the diffuse emission can be described by a power-law model plus a plasma component with photon index Γ ∼ 1.0 and plasma temperature kT ∼ 0.2 keV. While the thermal component is apparently uniform, the non-thermal contribution falls off exponentially from the core. The observed properties could possibly be explained in the context of multiple shocks resulting from the collisions among the stellar wind in the cluster and the inverse Compton scattering between the pulsar wind and the relic photons.

NARROW-LINE X-RAY-SELECTED GALAXIES IN THE CHANDRA -COSMOS FIELD. I. OPTICAL SPECTROSCOPIC CATALOG

Energy Technology Data Exchange (ETDEWEB)

Pons, E.; Watson, M. G. [University of Leicester, Leicester (United Kingdom); Elvis, M.; Civano, F. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

2016-04-20

The COSMOS survey is a large and deep survey with multiwavelength observations of sources from X-rays to the UV, allowing an extensive study of their properties. The central 0.9 deg{sup 2} of the COSMOS field have been observed by Chandra with a sensitivity up to 1.9 × 10{sup −16} erg cm{sup −2} s{sup −1} in the full (0.5–10 keV) band. Photometric and spectroscopic identification of the Chandra -COSMOS (C-COSMOS) sources is available from several catalogs and campaigns. Despite the fact that the C-COSMOS galaxies have a reliable spectroscopic redshift in addition to a spectroscopic classification, the emission-line properties of this sample have not yet been measured. We present here the creation of an emission-line catalog of 453 narrow-line sources from the C-COSMOS spectroscopic sample. We have performed spectral fitting for the more common lines in galaxies ([O ii] λ 3727, [Ne iii] λ 3869, H β , [O iii] λλ 4959, 5007, H α , and [N ii] λλ 6548, 6584). These data provide an optical classification for 151 (i.e., 33%) of the C-COSMOS narrow-line galaxies based on emission-line diagnostic diagrams.

Einstein pictures the x-ray sky

International Nuclear Information System (INIS)

Hartline, B.K.

1979-01-01

The second High Energy Astronomy Observatory (HEAO-2, Einstein) is revolutionizing x-ray astronomy just as its namesake revolutionized physics. Earlier x-ray observatories, including HEAO-1, were designed to scan the sky for x-ray emitters. With Einstein, the challenge has shifted from discovering x-ray sources to understanding the processes producing the x-rays. But having 500 times the sensitivity of previous detectors, Einstein makes more than its share of discoveries, too. For example, it sees distant quasars and clusters of galaxies that can barely be detected by the largest optical telescopes

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.

X-ray Point Source Populations in Spiral and Elliptical Galaxies

Science.gov (United States)

Colbert, E.; Heckman, T.; Weaver, K.; Strickland, D.

2002-01-01

The hard-X-ray luminosity of non-active galaxies has been known to be fairly well correlated with the total blue luminosity since the days of the Einstein satellite. However, the origin of this hard component was not well understood. Some possibilities that were considered included X-ray binaries, extended upscattered far-infrared light via the inverse-Compton process, extended hot 107 K gas (especially in ellipitical galaxies), or even an active nucleus. Chandra images of normal, elliptical and starburst galaxies now show that a significant amount of the total hard X-ray emission comes from individual point sources. We present here spatial and spectral analyses of the point sources in a small sample of Chandra obervations of starburst galaxies, and compare with Chandra point source analyses from comparison galaxies (elliptical, Seyfert and normal galaxies). We discuss possible relationships between the number and total hard luminosity of the X-ray point sources and various measures of the galaxy star formation rate, and discuss possible options for the numerous compact sources that are observed.

Dissecting Diffuse X-ray Emission in 30 Doradus with T-ReX

Science.gov (United States)

Townsley, Leisa K.; Broos, Patrick

2017-08-01

30 Doradus (the Tarantula Nebula) offers us a microscope on starburst astrophysics, having endured 25 Myrs of the birth and death of the most massive stars known. Across 30 Dor's 250-pc extent, stellar winds and supernovae have carved its ISM into an amazing display of arcs, pillars, and bubbles. For over 40 years, we have also known that 30 Dor is a bright X-ray emitter, so its familiar stars and cold ISM structures suffer irradiation by multi-million-degree plasmas. The 2-Ms Chandra X-ray Visionary Project ``The Tarantula -- Revealed by X-rays'' (T-ReX) exploits Chandra's fine spatial resolution and the ACIS-I field of view to study ISM interfaces on 1--10 pc scales across the entire 30 Dor complex. Here we give preliminary results from ongoing analyses of these data, focusing on the diffuse X-ray emission. Massive star winds and cavity supernovae over the millenia have contributed to a broad mix of X-ray-emitting plasmas and absorbing columns, showing that 30 Dor's hot ISM is just as complex and confusing as that seen at colder temperatures.

CORRELATION OF CHANDRA PHOTONS WITH THE RADIO GIANT PULSES FROM THE CRAB PULSAR

International Nuclear Information System (INIS)

Bilous, A. V.; McLaughlin, M. A.; Kondratiev, V. I.; Ransom, S. M.

2012-01-01

No apparent correlation was found between giant pulses (GPs) and X-ray photons from the Crab pulsar during 5.4 hr of simultaneous observations with the Green Bank Telescope at 1.5 GHz and Chandra X-Ray Observatory primarily in the energy range of 1.5-4.5 keV. During the Crab pulsar periods with GPs, the X-ray flux in radio emission phase windows does not change more than by ±10% for main pulse (MP) GPs and ±30% for interpulse (IP) GPs. During GPs themselves, the X-ray flux does not change by more than two times for MP GPs and five times for IP GPs. All limits quoted are compatible with 2σ fluctuations of the X-ray flux around the sets of false GPs with random arrival times. The results speak in favor of changes in plasma coherence as the origin of GPs. However, the results do not rule out variations in the rate of particle creation if the particles that emit coherent radio emission are mostly at the lowest Landau level.

Magnetically-coupled microcalorimeter arrays for x-ray astrophysics

Science.gov (United States)

Bandler, Simon

The "X-ray Surveyor" has been listed by NASA as one of the four major large mission concepts to be studied in the next Astrophysics Decadal Review in its preliminary list of large concepts. One of the key instruments on such a mission would be a very large format X-ray microcalorimeter array, with an array size of greater than 100 thousand pixels. Magnetically-coupled microcalorimeters (MCC) are one of the technologies with the greatest potential to meet the requirements of this mission, and this proposal is one to carry out research specifically to reach the goals of this vision. The "X-ray Surveyor" is a concept for a future mission that will make X-ray observations that are instrumental to understanding the quickly emerging population of galaxies and supermassive black holes at z ~10. The observations will trace the formation of galaxies and their assembly into large-scale structures starting from the earliest possible epochs. This mission would be observing baryons and large-scale physical processes outside of the very densest regions in the local Universe. This can be achieved with an X-ray observatory with similar angular resolution as Chandra but with significantly improved optic area and detector sensitivity. Chandra-scale angular resolution (1" or better) is essential in building more powerful, higher throughput observatories to avoid source confusion and remain photon-limited rather than background-limited. A prime consideration for the microcalorimeter camera on this type of mission is maintaining ~ 1 arcsec spatial resolution over the largest possible field of view, even if this means a slight trade-off against the spectral resolution. A uniform array of 1" pixels covering at least 5'x5' field of view is desired. To reduce the number of sensors read out, in geometries where extremely fine pitch (~50 microns) is desired, the most promising technologies are those in which a thermal sensor such an MCC can read out a sub-array of 20-25 individual 1'�

Searching for faint AGN in the CDFS: an X-ray (Chandra) vs optical variability (HST) comparison.

Science.gov (United States)

Georgantopoulos, I.; Pouliasis, E.; Bonanos, A.; Sokolovsky, K.; Yang, M.; Hatzidimitriou, D.; Bellas, I.; Gavras, P.; Spetsieri, Z.

2017-10-01

X-ray surveys are believed to be the most efficient way to detect AGN. Recently though, optical variability studies are claimed to probe even fainter AGN. We are presenting results from an HST study aimed to identify Active Galactic Nuclei (AGN) through optical variability selection in the CDFS.. This work is part of the 'Hubble Catalogue of Variables'project of ESA that aims to identify variable sources in the Hubble Source Catalogue.' In particular, we used Hubble Space Telescope (HST) z-band images taken over 5 epochs and performed aperture photometry to derive the lightcurves of the sources. Two statistical methods (standard deviation & interquartile range) resulting in a final sample of 175 variable AGN candidates, having removed the artifacts by visual inspection and known stars and supernovae. The fact that the majority of the sources are extended and variable indicates AGN activity. We compare the efficiency of the method by comparing with the 7Ms Chandra detections. Our work shows that the optical variability probes AGN at comparable redshifts but at deeper optical magnitudes. Our candidate AGN (non detected in X-rays) have luminosities of L_x<6×10^{40} erg/sec at z˜0.7 suggesting that these are associated with low luminosity Seyferts and LINERS.

Studies in the X-Ray Emission of Clusters of Galaxies and Other Topics

Science.gov (United States)

Vrtilek, Jan; Thronson, Harley (Technical Monitor)

2001-01-01

The paper discusses the following: (1) X-ray study of groups of galaxies with Chandra and XMM. (2) X-ray properties of point sources in Chandra deep fields. (3) Study of cluster substructure using wavelet techniques. (4) Combined study of galaxy clusters with X-ray and the S-Z effect. Groups of galaxies are the fundamental building blocks of large scale structure in the Universe. X-ray study of the intragroup medium offers a powerful approach to addressing some of the major questions that still remain about almost all aspects of groups: their ages, origins, importance of composition of various galaxy types, relations to clusters, and origin and enrichment of the intragroup gas. Long exposures with Chandra have opened new opportunities for the study of X-ray background. The presence of substructure within clusters of galaxies has substantial implications for our understanding of cluster evolution as well as fundamental questions in cosmology.

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.

CIAO: A Modern Data Analysis System for X-Ray Astronomy

Science.gov (United States)

Fruscione, Antonella

2017-08-01

It is now eighteen years after launch and Chandra continues to produce spectacular results!A portion of the success is to be attributed to the data analysis software CIAO (Chandra Interactive Analysis of Observations) that the Chandra X-Ray Center (CXC) continues to improve and release year after year.CIAO is downloaded more than 1200 times a year and it is used by a wide variety of users around the world: from novice to experienced X-ray astronomers, high school, undergraduate and graduate students, archival users (many new to X-ray or Chandra data), users with extensive resources and others from smaller countries and institutions.The scientific goals and kinds of datasets and analysis cover a wide range: observations spanning from days to years, different instrument configurations and different kinds of targets, from pointlike stars and quasars, to fuzzy galaxies and clusters, to moving solar objects. These different needs and goals require a variety of specialized software and careful and detailed documentation which is what the CIAO software provides. In general, we strive to build a software system which is easy for beginners, yet powerful for advanced users.The complexity of the Chandra data require a flexible data analysis system which provides an environment where the users can apply our tools, but can also explore and construct their own applications. The main purpose of this talk is to present CIAO as a modern data analysis system for X-ray data analysis.CIAO has grown tremendously over the years and we will highlight (a) the most recent advancements with a particular emphasis on the newly developed high-level scripts which simplify the analysis steps for the most common cases making CIAO more accessible to all users - including beginners and users who are not X-ray astronomy specialists, (b) the python-based Sherpa modelling and fitting application and the new stand-alone version openly developed and distributed on Github and (c) progress on methods to

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

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

Chandra X-ray Observatory - NASA's flagship X-ray telescope

Science.gov (United States)

Supernovas are some of the most dramatic events in the cosmos. These titanic events send shock waves rumbling of the most dramatic events in the cosmos. These titanic events send shock waves rumbling through

Revealing the nature of the ULX and X-ray population of the spiral galaxy NGC 4088

Energy Technology Data Exchange (ETDEWEB)

Mezcua, M. [Instituto de Astrofísica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Fabbiano, G. [Harvard-Smithsonian Center for Astrophysics (CfA), 60 Garden Street, Cambridge, MA 02138 (United States); Gladstone, J. C. [Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada); Farrell, S. A. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Soria, R., E-mail: mmezcua@iac.es [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)

2014-04-20

We present the first Chandra and Swift X-ray study of the spiral galaxy NGC 4088 and its ultraluminous X-ray source (ULX N4088-X1). We also report very long baseline interferometry (VLBI) observations at 1.6 and 5 GHz performed quasi-simultaneously with the Swift and Chandra observations, respectively. Fifteen X-ray sources are detected by Chandra within the D25 ellipse of NGC 4088, from which we derive the X-ray luminosity function (XLF) of this galaxy. We find the XLF is very similar to those of star-forming galaxies and estimate a star-formation rate of 4.5 M {sub ☉} yr{sup –1}. The Chandra detection of the ULX yields its most accurate X-ray position, which is spatially coincident with compact radio emission at 1.6 GHz. The ULX Chandra X-ray luminosity, L {sub 0.2-10.0} {sub keV} = 3.4 × 10{sup 39} erg s{sup –1}, indicates that N4088-X1 could be located at the high-luminosity end of the high-mass X-ray binary (HMXB) population of NGC 4088. The estimates of the black hole (BH) mass and ratio of radio to X-ray luminosity of N4088-X1 rule out a supermassive BH nature. The Swift X-ray spectrum of N4088-X1 is best described by a thermal Comptonization model and presents a statistically significant high-energy cutoff. We conclude that N4088-X1 is most likely a stellar remnant BH in an HMXB, probably fed by Roche lobe overflow, residing in a super-Eddington ultraluminous state. The 1.6 GHz VLBI source is consistent with radio emission from possible ballistic jet ejections in this state.

CHANDRA AND SUZAKU OBSERVATIONS OF THE Be/X-RAY STAR HD110432

International Nuclear Information System (INIS)

Torrejón, J. M.; Schulz, N. S.; Nowak, M. A.

2012-01-01

We present an analysis of a pointed 141 ks Chandra high-resolution transmission gratings observation of the Be X-ray emitting star HD110432, a prominent member of the γ Cas analogs. This observation represents the first high-resolution spectrum taken for this source as well as the longest uninterrupted observation of any γ Cas analog. The Chandra light curve shows a high variability but its analysis fails to detect any coherent periodicity up to a frequency of 0.05 Hz. Hardness ratio versus intensity analyses demonstrate that the relative contributions of the [1.5-3] Å, [3-6] Å, and [6-16] Å energy bands to the total flux change rapidly in the short term. The analysis of the Chandra High Energy Transmission Grating (HETG) spectrum shows that, to correctly describe the spectrum, three model components are needed. Two of those components are optically thin thermal plasmas of different temperatures (kT ≈ 8-9 and 0.2-0.3 keV, respectively) described by the models vmekal or bvapec. The Fe abundance in each of these two components appears equal within the errors and is slightly subsolar with Z ≈ 0.75 Z ☉ . The bvapec model better describes the Fe L transitions, although it cannot fit well the Na XI Lyα line at 10.02 Å, which appears to be overabundant. Two different models seem to describe well the third component. One possibility is a third hot optically thin thermal plasma at kT = 16-21 keV with an Fe abundance Z ≈ 0.3 Z ☉ , definitely smaller than for the other two thermal components. Furthermore, the bvapec model describes well the Fe K shell transitions because it accounts for the turbulence broadening of the Fe XXV and Fe XXVI lines with a v turb ≈ 1200 km s –1 . These two lines, contributed mainly by the hot thermal plasma, are significantly wider than the Fe Kα line whose FWHM ☉ , and a very hot second plasma with kT ≈ 33 keV or, alternatively, a power law with photon index of Γ = 1.58. In either case, each one of the two components

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

A Deep Chandra ACIS Study of NGC 4151. I. The X-ray Morphology of the 3 kpc Diameter Circum-nuclear Region and Relation to the Cold Interstellar Medium

Science.gov (United States)

Wang, Junfeng; Fabbiano, Giuseppina; Risaliti, Guido; Elvis, Martin; Karovska, Margarita; Zezas, Andreas; Mundell, Carole G.; Dumas, Gaelle; Schinnerer, Eva

2011-03-01

We report on the imaging analysis of ~200 ks sub-arcsecond resolution Chandra Advanced CCD Imaging Spectrometer (ACIS-S) observations of the nearby Seyfert 1 galaxy NGC 4151. Bright, structured soft X-ray emission is observed to extend from 30 pc to 1.3 kpc in the southwest from the nucleus, much farther than seen in earlier X-ray studies. The terminus of the northeastern X-ray emission is spatially coincident with a CO gas lane, where the outflow likely encounters dense gas in the host galactic disk. X-ray emission is also detected outside the boundaries of the ionization cone, which indicates that the gas there is not completely shielded from the nuclear continuum, as would be the case for a molecular torus collimating the bicone. In the central r < 200 pc region, the subpixel processing of the ACIS data recovers the morphological details on scales of <30 pc (<0farcs5) first discovered in Chandra High Resolution Camera images. The X-ray emission is more absorbed toward the boundaries of the ionization cone, as well as perpendicular to the bicone along the direction of a putative torus in NGC 4151. The innermost region where X-ray emission shows the highest hardness ratio is spatially coincident with the near-infrared-resolved H2 emission and dusty spirals we find in an Hubble Space Telescope V - H color image. The agreement between the observed H2 line flux and the value predicted from X-ray-irradiated molecular cloud models supports photo-excitation by X-rays from the active nucleus as the origin of the H2 line, although contribution from UV fluorescence or collisional excitation cannot be ruled out with current data. The discrepancy between the mass of cold molecular gas inferred from recent CO and near-infrared H2 observations may be explained by the anomalous CO abundance in this X-ray-dominated region. The total H2 mass derived from the X-ray observation agrees with the recent measurement by Storchi-Bergmann et al.

INNOVATIONS IN THE ANALYSIS OF CHANDRA-ACIS OBSERVATIONS

International Nuclear Information System (INIS)

Broos, Patrick S.; Townsley, Leisa K.; Feigelson, Eric D.; Getman, Konstantin V.; Garmire, Gordon P.; Bauer, Franz E.

2010-01-01

As members of the instrument team for the Advanced CCD Imaging Spectrometer (ACIS) on NASA's Chandra X-ray Observatory and as Chandra General Observers, we have developed a wide variety of data analysis methods that we believe are useful to the Chandra community, and have constructed a significant body of publicly available software (the ACIS Extract package) addressing important ACIS data and science analysis tasks. This paper seeks to describe these data analysis methods for two purposes: to document the data analysis work performed in our own science projects and to help other ACIS observers judge whether these methods may be useful in their own projects (regardless of what tools and procedures they choose to implement those methods). The ACIS data analysis recommendations we offer here address much of the workflow in a typical ACIS project, including data preparation, point source detection via both wavelet decomposition and image reconstruction, masking point sources, identification of diffuse structures, event extraction for both point and diffuse sources, merging extractions from multiple observations, nonparametric broadband photometry, analysis of low-count spectra, and automation of these tasks. Many of the innovations presented here arise from several, often interwoven, complications that are found in many Chandra projects: large numbers of point sources (hundreds to several thousand), faint point sources, misaligned multiple observations of an astronomical field, point source crowding, and scientifically relevant diffuse emission.

CALIBRATION OF THE NuSTAR HIGH-ENERGY FOCUSING X-RAY TELESCOPE

Energy Technology Data Exchange (ETDEWEB)

Madsen, Kristin K.; Harrison, Fiona A.; Grefenstette, Brian W.; Miyasaka, Hiromasa; Forster, Karl; Fuerst, Felix; Rana, Vikram; Walton, Dominic J. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Markwardt, Craig B. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); An, Hongjun [Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada); Bachetti, Matteo [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Kitaguchi, Takao [RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Bhalerao, Varun [Inter-University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India); Boggs, Steve; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektronvej 327, DK-2800 Lyngby (Denmark); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, NY 10027 (United States); Perri, Matteo; Puccetti, Simonetta [ASI Science Data Center, via Galileo Galilei, I-00044, Frascati (Italy); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); and others

2015-09-15

We present the calibration of the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray satellite. We used the Crab as the primary effective area calibrator and constructed a piece-wise linear spline function to modify the vignetting response. The achieved residuals for all off-axis angles and energies, compared to the assumed spectrum, are typically better than ±2% up to 40 keV and 5%–10% above due to limited counting statistics. An empirical adjustment to the theoretical two-dimensional point-spread function (PSF) was found using several strong point sources, and no increase of the PSF half-power diameter has been observed since the beginning of the mission. We report on the detector gain calibration, good to 60 eV for all grades, and discuss the timing capabilities of the observatory, which has an absolute timing of ±3 ms. Finally, we present cross-calibration results from two campaigns between all the major concurrent X-ray observatories (Chandra, Swift, Suzaku, and XMM-Newton), conducted in 2012 and 2013 on the sources 3C 273 and PKS 2155-304, and show that the differences in measured flux is within ∼10% for all instruments with respect to NuSTAR.

ORBITAL VARIATION OF THE X-RAY EMISSION FROM THE DOUBLE NEUTRON STAR BINARY J1537+1155

International Nuclear Information System (INIS)

Durant, Martin; Kargaltsev, Oleg; Volkov, Igor; Pavlov, George G.

2011-01-01

We observed the double neutron star binary (DNSB) containing PSR J1537+1155 (also known as B1534+12) with the Chandra X-Ray Observatory. This is one of the two DNSBs detected in X-rays and the only one where a hint of variability with orbital phase was found (in the previous Chandra observation). Our follow-up observation supports the earlier result: the distribution of photon arrival times with orbital phase again shows a deficit around apastron. The significance of the deficit in the combined data set exceeds 99%. Such an orbital light curve suggests that the X-ray emission is seen only when neutron star (NS) B passes through the equatorial pulsar wind of NS A. We describe statistical tests that we used to determine the significance of the deficit, and conclusions that can be drawn from its existence, such as interaction of the pulsar wind with the NS companion. We also provide better constrained spectral model parameters obtained from the joint spectral fits to the data from both observations. A power law successfully fits the data, with best-fit photon index Γ = 3.1 ± 0.4 and unabsorbed flux f = (3.2 ± 0.8) × 10 –15 erg s –1 cm –2 (0.3-8 keV range).

The Chandra Source Catalog: X-ray Aperture Photometry

Science.gov (United States)

Kashyap, Vinay; Primini, F. A.; Glotfelty, K. J.; Anderson, C. S.; Bonaventura, N. R.; Chen, J. C.; Davis, J. E.; Doe, S. M.; Evans, I. N.; Evans, J. D.; Fabbiano, G.; Galle, E. C.; Gibbs, D. G., II; Grier, J. D.; Hain, R.; Hall, D. M.; Harbo, P. N.; He, X.; Houck, J. C.; Karovska, M.; Lauer, J.; McCollough, M. L.; McDowell, J. C.; Miller, J. B.; Mitschang, A. W.; Morgan, D. L.; Nichols, J. S.; Nowak, M. A.; Plummer, D. A.; Refsdal, B. L.; Rots, A. H.; 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) represents a reanalysis of the entire ACIS and HRC imaging observations over the 9-year Chandra mission. We describe here the method by which fluxes are measured for detected sources. Source detection is carried out on a uniform basis, using the CIAO tool wavdetect. Source fluxes are estimated post-facto using a Bayesian method that accounts for background, spatial resolution effects, and contamination from nearby sources. We use gamma-function prior distributions, which could be either non-informative, or in case there exist previous observations of the same source, strongly informative. The current implementation is however limited to non-informative priors. The resulting posterior probability density functions allow us to report the flux and a robust credible range on it.

The Einstein Observatory Extended Medium-Sensitivity Survey. I - X-ray data and analysis

Science.gov (United States)

Gioia, I. M.; Maccacaro, T.; Schild, R. E.; Wolter, A.; Stocke, J. T.

1990-01-01

This paper presents the results of the analysis of the X-ray data and the optical identification for the Einstein Observatory Extended Medium-Sensitivity Survey (EMSS). The survey consists of 835 serendipitous sources detected at or above 4 times the rms level in 1435 imaging proportional counter fields with centers located away from the Galactic plane. Their limiting sensitivities are about (5-300) x 10 to the -14th ergs/sq cm sec in the 0.3-3.5-keV energy band. A total area of 778 square deg of the high-Galactic-latitude sky has been covered. The data have been analyzed using the REV1 processing system, which takes into account the nonuniformities of the detector. The resulting EMSS catalog of X-ray sources is a flux-limited and homogeneous sample of astronomical objects that can be used for statistical studies.

DISCOVERY OF X-RAY EMISSION FROM YOUNG SUNS IN THE SMALL MAGELLANIC CLOUD

International Nuclear Information System (INIS)

Oskinova, L. M.; Hainich, R.; Sun, W.; Chen, Y.; Evans, C. J.; Hénault-Brunet, V.; Chu, Y.-H.; Gruendl, R. A.; Gallagher, J. S. III; Guerrero, M. A.; Güdel, M.; Silich, S.; Nazé, Y.; Reyes-Iturbide, J.

2013-01-01

We report the discovery of extended X-ray emission within the young star cluster NGC 602a in the Wing of the Small Magellanic Cloud (SMC) based on observations obtained with the Chandra X-Ray Observatory. X-ray emission is detected from the cluster core area with the highest stellar density and from a dusty ridge surrounding the H II region. We use a census of massive stars in the cluster to demonstrate that a cluster wind or wind-blown bubble is unlikely to provide a significant contribution to the X-ray emission detected from the central area of the cluster. We therefore suggest that X-ray emission at the cluster core originates from an ensemble of low- and solar-mass pre-main-sequence (PMS) stars, each of which would be too weak in X-rays to be detected individually. We attribute the X-ray emission from the dusty ridge to the embedded tight cluster of the newborn stars known in this area from infrared studies. Assuming that the levels of X-ray activity in young stars in the low-metallicity environment of NGC 602a are comparable to their Galactic counterparts, then the detected spatial distribution, spectral properties, and level of X-ray emission are largely consistent with those expected from low- and solar-mass PMS stars and young stellar objects (YSOs). This is the first discovery of X-ray emission attributable to PMS stars and YSOs in the SMC, which suggests that the accretion and dynamo processes in young, low-mass objects in the SMC resemble those in the Galaxy.

Spectral state transitions of the Ultraluminous X-ray Source IC 342 X-1

Science.gov (United States)

Marlowe, H.; Kaaret, P.; Lang, C.; Feng, H.; Grisé, F.; Miller, N.; Cseh, D.; Corbel, S.; Mushotzky, R. F.

2014-10-01

We observed the Ultraluminous X-ray Source (ULX) IC 342 X-1 simultaneously in X-ray and radio with Chandra and the JVLA to investigate previously reported unresolved radio emission coincident with the ULX. The Chandra data reveal a spectrum that is much softer than observed previously and is well modelled by a thermal accretion disc spectrum. No significant radio emission above the rms noise level was observed within the region of the ULX, consistent with the interpretation as a thermal state though other states cannot be entirely ruled out with the current data. We estimate the mass of the black hole using the modelled inner disc temperature to be 30 M_{⊙} ≲ M√{cosi}≲ 200 M_{⊙} based on a Shakura-Sunyaev disc model. Through a study of the hardness and high-energy curvature of available X-ray observations, we find that the accretion state of X-1 is not determined by luminosity alone.

Exploring the X-Ray Universe

Science.gov (United States)

Seward, Frederick D.; Charles, Philip A.

1995-11-01

Exploring the X-Ray Universe describes the view of the stars and galaxies that is obtained through X-ray telescopes. X-rays, which are invisible to human sight, are created in the cores of active galaxies, in cataclysmic stellar explosions, and in streams of gas expelled by the Sun and stars. The window on the heavens used by the X-ray astronomers shows the great drama of cosmic violence on the grandest scale. This account of X-ray astronomy incorporates the latest findings from several observatories operating in space. These include the Einstein Observatory operated by NASA, and the EXOSAT satellite of the European Space Agency. The book covers the entire field, with chapters on stars, supernova remnants, normal and active galaxies, clusters of galaxies, the diffuse X-ray background, and much more. The authors review basic principles, include the necessary historical background, and explain exactly what we know from X-ray observations of the Universe.

New technology and techniques for x-ray mirror calibration at PANTER

Science.gov (United States)

Freyberg, Michael J.; Budau, Bernd; Burkert, Wolfgang; Friedrich, Peter; Hartner, Gisela; Misaki, Kazutami; Mühlegger, Martin

2008-07-01

The PANTER X-ray Test Facility has been utilized successfully for developing and calibrating X-ray astronomical instrumentation for observatories such as ROSAT, Chandra, XMM-Newton, Swift, etc. Future missions like eROSITA, SIMBOL-X, or XEUS require improved spatial resolution and broader energy band pass, both for optics and for cameras. Calibration campaigns at PANTER have made use of flight spare instrumentation for space applications; here we report on a new dedicated CCD camera for on-ground calibration, called TRoPIC. As the CCD is similar to ones used for eROSITA (pn-type, back-illuminated, 75 μm pixel size, frame store mode, 450 μm micron wafer thickness, etc.) it can serve as prototype for eROSITA camera development. New techniques enable and enhance the analysis of measurements of eROSITA shells or silicon pore optics. Specifically, we show how sub-pixel resolution can be utilized to improve spatial resolution and subsequently the characterization of of mirror shell quality and of point spread function parameters in particular, also relevant for position reconstruction of astronomical sources in orbit.

New insights into the X-ray properties of nearby barred spiral galaxy NGC 1672

Science.gov (United States)

Jenkins, L. P.; Brnadt, W. N.; Colbert, E. J. M.; Levan, A. J.; Roberts, T. P.; Ward, M. J.; Zezas, A.

2008-02-01

We present some preliminary results from new Chandra and XMM-Newton X-ray observations of the nearby barred spiral galaxy NGC1672. It shows dramatic nuclear and extra-nuclear star formation activity, including starburst regions located near each end of its strong bar, both of which host ultraluminous X-ray sources (ULXs). With the new high-spatial-resolution Chandra imaging, we show for the first time that NGC1672 possesses a faint ($L(X)~10^39 erg/s), hard central X-ray source surrounded by an X-ray bright circumnuclear starburst ring that dominates the X-ray emission in the region. The central source may represent low-level AGN activity, or alternatively the emission from X-ray binaries associated with star-formation in the nucleus.

X-RAY PROPERTIES OF INTERMEDIATE-MASS BLACK HOLES IN ACTIVE GALAXIES. II. X-RAY-BRIGHT ACCRETION AND POSSIBLE EVIDENCE FOR SLIM DISKS

International Nuclear Information System (INIS)

Desroches, Louis-Benoit; Greene, Jenny E.; Ho, Luis C.

2009-01-01

We present X-ray properties of optically selected intermediate-mass (∼10 5 -10 6 M sun ) black holes (BHs) in active galactic nuclei (AGNs), using data from the Chandra X-Ray Observatory. Our observations are a continuation of a pilot study by Greene and Ho. Of the eight objects observed, five are detected with X-ray luminosities in the range L 0.5-2keV = 10 41 -10 43 erg s -1 , consistent with the previously observed sample. Objects with enough counts to extract a spectrum are well fit by an absorbed power law. We continue to find a range of soft photon indices 1 s -Γ s , consistent with previous AGN studies, but generally flatter than other narrow-line Seyfert 1 active nuclei (NLS1s). The soft photon index correlates strongly with X-ray luminosity and Eddington ratio, but does not depend on BH mass. There is no justification for the inclusion of any additional components, such as a soft excess, although this may be a function of the relative inefficiency of detecting counts above 2 keV in these relatively shallow observations. As a whole, the X-ray-to-optical spectral slope α ox is flatter than in more massive systems, even other NLS1s. Only X-ray-selected NLS1s with very high Eddington ratios share a similar α ox . This is suggestive of a physical change in the accretion structure at low masses and at very high accretion rates, possibly due to the onset of slim disks. Although the detailed physical explanation for the X-ray loudness of these intermediate-mass BHs is not certain, it is very striking that targets selected on the basis of optical properties should be so distinctly offset in their broader spectral energy distributions.

Multiwavelength study of Chandra X-ray sources in the Antennae

Science.gov (United States)

Clark, D. M.; Eikenberry, S. S.; Brandl, B. R.; Wilson, J. C.; Carson, J. C.; Henderson, C. P.; Hayward, T. L.; Barry, D. J.; Ptak, A. F.; Colbert, E. J. M.

2011-01-01

We use Wide-field InfraRed Camera (WIRC) infrared (IR) images of the Antennae (NGC 4038/4039) together with the extensive catalogue of 120 X-ray point sources to search for counterpart candidates. Using our proven frame-tie technique, we find 38 X-ray sources with IR counterparts, almost doubling the number of IR counterparts to X-ray sources that we first identified. In our photometric analysis, we consider the 35 IR counterparts that are confirmed star clusters. We show that the clusters with X-ray sources tend to be brighter, Ks≈ 16 mag, with (J-Ks) = 1.1 mag. We then use archival Hubble Space Telescope (HST) images of the Antennae to search for optical counterparts to the X-ray point sources. We employ our previous IR-to-X-ray frame-tie as an intermediary to establish a precise optical-to-X-ray frame-tie with <0.6 arcsec rms positional uncertainty. Due to the high optical source density near the X-ray sources, we determine that we cannot reliably identify counterparts. Comparing the HST positions to the 35 identified IR star cluster counterparts, we find optical matches for 27 of these sources. Using Bruzual-Charlot spectral evolutionary models, we find that most clusters associated with an X-ray source are massive, and young, ˜ 106 yr.

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

Imaging X-ray astronomy

International Nuclear Information System (INIS)

Elvis, M.

1990-01-01

The launch of the High Energy Astrophysical Observatory, more appealingly called the Einstein Observatory, marked one of the most revolutionary steps taken in astrophysics this century. Its greater sensitivity compared with earlier satellites and its ability to make high spacial and spectral resolution observations transformed X-ray astronomy. This book is based on a Symposium held in Cambridge, Massachusetts, to celebrate a decade of Einstein Observatory's achievements. It discusses the contributions that this satellite has made to each area of modern astrophysics and the diversity of the ongoing work based on Einstein data. There is a guide to each of the main data bases now coming on-line to increase the availability and to preserve this valuable archive for the future. A review of NASA's next big X-ray mission, AXAF, and a visionary program for novel X-ray astronomy satellites by Riccardo Giacconi conclude this wide-ranging volume. (author)

Chandra Data Reveal Rapidly Whirling Black Holes

Science.gov (United States)

2008-01-01

A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly. The whirling of these giant black holes drives powerful jets that pump huge amounts of energy into their environment and affects galaxy growth. A team of scientists compared leading theories of jets produced by rotating supermassive black holes with Chandra data. A sampling of nine giant galaxies that exhibit large disturbances in their gaseous atmospheres showed that the central black holes in these galaxies must be spinning at near their maximum rates. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Erratic Black Hole Regulates Itself "We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light," said Rodrigo Nemmen, a visiting graduate student at Penn State University, and lead author of a paper on the new results presented at American Astronomical Society in Austin, Texas. The research reinforces other, less direct methods previously used which have indicated that some stellar and supermassive black holes are spinning rapidly. According to Einstein's theory, a rapidly spinning black hole makes space itself rotate. This effect, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet. Computer simulations by other authors have suggested that black holes may acquire their rapid spins when galaxies merge, and through the accretion of gas from their surroundings. "Extremely fast spin might be very common for large

ON THE X-RAY BALDWIN EFFECT IN ACTIVE GALACTIC NUCLEI OBSERVED BY THE CHANDRA HIGH-ENERGY GRATING

International Nuclear Information System (INIS)

Shu, X. W.; Wang, J. X.; Jiang, P.; Zhou, Y. Y.; Yaqoob, T.

2012-01-01

Using Chandra high-energy grating (HEG) observations of 32 active galactic nuclei (AGNs), we present a systematic study of the X-ray Baldwin effect (XBE; i.e., the anti-correlation between the narrow Fe Kα line equivalent width (EW) and X-ray continuum luminosity for AGN samples) with the highest spectral resolution currently available. We have previously reported an anti-correlation with EW∝L –0.22 2-10keV in an HEG sample, and the correlation is much weaker after averaging multiple observations of individual AGNs (EW∝L –0.13 2-10keV ). This indicates that rapid variation in the X-ray continuum plays an important role in producing the XBE, and such an effect should also be visible in individual AGNs. In this Letter, by normalizing the line EWs and continuum luminosities to the time-averaged values for each AGN in our sample with multiple HEG observations, we find a strong anti-correlation between EW and L X (EW/(EW)∝(L/(L)) –0.82±0.10 ), consistent with the XBE expected in an individual AGN if the narrow line flux remains constant while the continuum varies. This is first observational evidence that the Fe Kα line flux in a large sample of AGNs lacks a corresponding response to the continuum variation, supporting the fact that the narrow Fe-K line emission originates from a region far from the nucleus. We then performed Monte Carlo simulations to address whether the global XBE can be produced by X-ray continuum variation solely, and found that such an interpretation of the XBE cannot be ruled out statistically. One should thus be very cautious before drawing any scientific conclusion based on an observed XBE.

Chandra High Resolution Imaging of NGC 1365 and NGC 4151

Science.gov (United States)

Wang, Junfeng; Fabbiano, G.; Elvis, M.; Risaliti, G.; Karovska, M.; Zezas, A.; Mazzarella, J. M.; Lord, S.; Howell, J. H.; Mundell, C. G.

2010-07-01

We present Chandra high resolution imaging of the circumnuclear regions of two nearby active galaxies, namely the starburst/AGN composite Seyfert 1.8 NGC 1365 and the archetypal Seyfert 1 NGC 4151. In NGC 1365, the X-ray morphology shows a biconical soft X-ray-emission region extending ~5 kpc in projection from the nucleus, coincident with the optical high-excitation outflows. Chandra HRC imaging of the NGC 4151 nucleus resolves X-ray emission from the 4 arcsec radio jet and the narrow line region (NLR) clouds. Our results demonstrate the unique power of spatially resolved spectroscopy with Chandra, and support previous claims that frequent jet-ISM interaction may explain why jets in Seyfert galaxies appear small, slow, and thermally dominated.

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

Dark Matter Reality Check: Chandra Casts Cloud On Alternative Theory

Science.gov (United States)

2002-10-01

New evidence from NASA's Chandra X-ray Observatory challenges an alternative theory of gravity that eliminates the need for dark matter. The observation also narrows the field for competing forms of dark matter, the elusive material thought to be the dominant form of matter in the universe. An observation of the galaxy NGC 720 shows it is enveloped in a slightly flattened, or ellipsoidal cloud of hot gas that has an orientation different from that of the optical image of the galaxy. The flattening is too large to be explained by theories in which stars and gas are assumed to contain most of the mass in the galaxy. "The shape and orientation of the hot gas cloud require it to be confined by an egg-shaped dark matter halo," said David Buote of the University of California, Irvine, and lead author of a report on this research in the 2002 September 20 issue of The Astrophysical Journal. "This means that dark matter is not just an illusion due to a shortcoming of the standard theory of gravity - it is real." According to the generally accepted standard theory of gravity, the hot X-ray cloud would need an additional source of gravity - a halo of dark matter - to keep the hot gas from expanding away. The mass of dark matter required would be about five to ten times the mass of the stars in the galaxy. If the dark matter tracked the optical light from the stars in the galaxy, the hot X-ray cloud would be more round than it is. The flattened shape of the hot gas cloud requires a flattened dark matter halo. An alternative theory of gravity called MOND, for Modified Newtonian Dynamics, was proposed in 1983 by Mordecai Milgrom of the Weizmann Institute in Israel, and has remained viable over the years. MOND does away with the need for dark matter by modifying the theory where the acceleration produced by gravity is very small, such as the outskirts of galaxies. However, MOND cannot explain the Chandra observation of NGC 720. This is apparently the first dynamical evidence that

The X-Ray Luminosity Functions of Field Low-Mass X-Ray Binaries in Early-Type Galaxies: Evidence for a Stellar Age Dependence

Science.gov (United States)

Lehmer, B. D.; Berkeley, M.; Zezas, A.; Alexander, D. M.; Basu-Zych, A.; Bauer, F. E.; Brandt, W. N.; Fragos, T.; Hornschemeier, A. E.; Kalogera, V.;

Cosmological constraints from Chandra observations of galaxy clusters.

Science.gov (United States)

Allen, Steven W

2002-09-15

Chandra observations of rich, relaxed galaxy clusters allow the properties of the X-ray gas and the total gravitating mass to be determined precisely. Here, we present results for a sample of the most X-ray luminous, dynamically relaxed clusters known. We show that the Chandra data and independent gravitational lensing studies provide consistent answers on the mass distributions in the clusters. The mass profiles exhibit a form in good agreement with the predictions from numerical simulations. Combining Chandra results on the X-ray gas mass fractions in the clusters with independent measurements of the Hubble constant and the mean baryonic matter density in the Universe, we obtain a tight constraint on the mean total matter density of the Universe, Omega(m), and an interesting constraint on the cosmological constant, Omega(Lambda). We also describe the 'virial relations' linking the masses, X-ray temperatures and luminosities of galaxy clusters. These relations provide a key step in linking the observed number density and spatial distribution of clusters to the predictions from cosmological models. The Chandra data confirm the presence of a systematic offset of ca. 40% between the normalization of the observed mass-temperature relation and the predictions from standard simulations. This finding leads to a significant revision of the best-fit value of sigma(8) inferred from the observed temperature and luminosity functions of clusters.

The Chandra Source Catalog 2.0: Estimating Source Fluxes

Science.gov (United States)

Primini, Francis Anthony; Allen, Christopher E.; Miller, Joseph; 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.; 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.; Paxson, Charles; Plummer, David A.; Rots, Arnold H.; Siemiginowska, Aneta; Sundheim, Beth A.; Tibbetts, Michael; Van Stone, David W.; Zografou, Panagoula

2018-01-01

The Second Chandra Source Catalog (CSC2.0) will provide information on approximately 316,000 point or compact extended x-ray sources, derived from over 10,000 ACIS and HRC-I imaging observations available in the public archive at the end of 2014. As in the previous catalog release (CSC1.1), fluxes for these sources will be determined separately from source detection, using a Bayesian formalism that accounts for background, spatial resolution effects, and contamination from nearby sources. However, the CSC2.0 procedure differs from that used in CSC1.1 in three important aspects. First, for sources in crowded regions in which photometric apertures overlap, fluxes are determined jointly, using an extension of the CSC1.1 algorithm, as discussed in Primini & Kashyap (2014ApJ...796…24P). Second, an MCMC procedure is used to estimate marginalized posterior probability distributions for source fluxes. Finally, for sources observed in multiple observations, a Bayesian Blocks algorithm (Scargle, et al. 2013ApJ...764..167S) is used to group observations into blocks of constant source flux.In this poster we present details of the CSC2.0 photometry algorithms and illustrate their performance in actual CSC2.0 datasets.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.

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

JOINT ANALYSIS OF X-RAY AND SUNYAEV-ZEL'DOVICH OBSERVATIONS OF GALAXY CLUSTERS USING AN ANALYTIC MODEL OF THE INTRACLUSTER MEDIUM

International Nuclear Information System (INIS)

Hasler, Nicole; Bulbul, Esra; Bonamente, Massimiliano; Landry, David; Carlstrom, John E.; Culverhouse, Thomas L.; Gralla, Megan; Greer, Christopher; Hennessy, Ryan; Leitch, Erik M.; Mantz, Adam; Marrone, Daniel P.; Plagge, Thomas; Hawkins, David; Lamb, James W.; Muchovej, Stephen; Joy, Marshall; Kolodziejczak, Jeffery; Miller, Amber; Mroczkowski, Tony

2012-01-01

We perform a joint analysis of X-ray and Sunyaev-Zel'dovich effect data using an analytic model that describes the gas properties of galaxy clusters. The joint analysis allows the measurement of the cluster gas mass fraction profile and Hubble constant independent of cosmological parameters. Weak cosmological priors are used to calculate the overdensity radius within which the gas mass fractions are reported. Such an analysis can provide direct constraints on the evolution of the cluster gas mass fraction with redshift. We validate the model and the joint analysis on high signal-to-noise data from the Chandra X-ray Observatory and the Sunyaev-Zel'dovich Array for two clusters, A2631 and A2204.

The universe in X-rays

CERN Document Server

Hasinger, Günther

2008-01-01

In the last 45 years, X-ray astronomy has become an integral part of modern astrophysics and cosmology. There is a wide range of astrophysical objects and phenomena, where X-rays provide crucial diagnostics. In particular they are well suited to study hot plasmas and matter under extreme physical conditions in compact objects. This book summarizes the present status of X-ray astronomy in terms of observational results and their astrophysical interpretation. It is written for students, astrophysicists as well a growing community of physicists interested in the field. An introduction including historical material is followed by chapters on X-ray astronomical instrumentation. The next two parts summarize in 17 chapters the present knowledge on various classes of X-ray sources in the galactic and extragalactic realm. While the X-ray astronomical highlights discussed in this book are mainly based on results from ROSAT, ASCA, RXTE, BeppoSAX, Chandra and XMM-Newton, a final chapter provides an outlook on observation...

Einstein Observatory survey of X-ray emission from solar-type stars - the late F and G dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Maggio, A.; Sciortino, S.; Vaiana, G.S.; Majer, P.; Bookbinder, J.

1987-04-01

Results of a volume-limited X-ray survey of stars of luminosity classes IV and V in the spectral range F7-G9 observed with the Einstein Observatory are presented. Using survival analysis techniques, the stellar X-ray luminosity function in the 0.15-4.0 keV energy band for both single and multiple sources. It is shown that the difference in X-ray luminosity between these two classes of sources is consistent with the superposition of individual components in multiple-component systems, whose X-ray properties are similar to those of the single-component sources. The X-ray emission of the stars in our sample is well correlated with their chromospheric CA II H-K line emission and with their projected equatorial rotational velocity. Comparison of the X-ray luminosity function constructed for the sample of the dG stars of the local population with the corresponding functions derived elsewhere for the Hyades, the Pleiades, and the Orion Ic open cluster confirms that the level of X-ray emission decreases with stellar age. 62 references.

Einstein Observatory survey of X-ray emission from solar-type stars - The late F and G dwarf stars

Science.gov (United States)

Maggio, A.; Sciortino, S.; Vaiana, G. S.; Majer, P.; Bookbinder, J.

1987-01-01

Results of a volume-limited X-ray survey of stars of luminosity classes IV and V in the spectral range F7-G9 observed with the Einstein Observatory are presented. Using survival analysis techniques, the stellar X-ray luminosity function in the 0.15-4.0 keV energy band for both single and multiple sources. It is shown that the difference in X-ray luminosity between these two classes of sources is consistent with the superposition of individual components in multiple-component systems, whose X-ray properties are similar to those of the single-component sources. The X-ray emission of the stars in our sample is well correlated with their chromospheric CA II H-K line emission and with their projected equatorial rotational velocity. Comparison of the X-ray luminosity function constructed for the sample of the dG stars of the local population with the corresponding functions derived elsewhere for the Hyades, the Pleiades, and the Orion Ic open cluster confirms that the level of X-ray emission decreases with stellar age.

The Frequency of Intrinsic X-Ray Weakness among Broad Absorption Line Quasars

Science.gov (United States)

Liu, Hezhen; Luo, B.; Brandt, W. N.; Gallagher, S. C.; Garmire, G. P.

2018-06-01

We present combined ≈14–37 ks Chandra observations of seven z = 1.6–2.7 broad absorption line (BAL) quasars selected from the Large Bright Quasar Survey (LBQS). These seven objects are high-ionization BAL (HiBAL) quasars, and they were undetected in the Chandra hard band (2–8 keV) in previous observations. The stacking analyses of previous Chandra observations suggested that these seven objects likely contain some candidates for intrinsically X-ray weak BAL quasars. With the new Chandra observations, six targets are detected. We calculate their effective power-law photon indices and hard-band flux weakness, and find that two objects, LBQS 1203+1530 and LBQS 1442–0011, show soft/steep spectral shapes ({{{Γ }}}eff}={2.2}-0.9+0.9 and {1.9}-0.8+0.9) and significant X-ray weakness in the hard band (by factors of ≈15 and 12). We conclude that the two HiBAL quasars are good candidates for intrinsically X-ray weak BAL quasars. The mid-infrared-to-ultraviolet spectral energy distributions of the two candidates are consistent with those of typical quasars. We constrain the fraction of intrinsically X-ray weak active galactic nuclei (AGNs) among HiBAL quasars to be ≈7%–10% (2/29–3/29), and we estimate it is ≈6%–23% (2/35–8/35) among the general BAL quasar population. Such a fraction is considerably larger than that among non-BAL quasars, and we suggest that intrinsically X-ray weak quasars are preferentially observed as BAL quasars. Intrinsically X-ray weak AGNs likely comprise a small minority of the luminous type 1 AGN population, and they should not affect significantly the completeness of these AGNs found in deep X-ray surveys.

Hydrostatic Chandra X-ray analysis of SPT-selected galaxy clusters - I. Evolution of profiles and core properties

Science.gov (United States)

Sanders, J. S.; Fabian, A. C.; Russell, H. R.; Walker, S. A.

2018-02-01

We analyse Chandra X-ray Observatory observations of a set of galaxy clusters selected by the South Pole Telescope using a new publicly available forward-modelling projection code, MBPROJ2, assuming hydrostatic equilibrium. By fitting a power law plus constant entropy model we find no evidence for a central entropy floor in the lowest entropy systems. A model of the underlying central entropy distribution shows a narrow peak close to zero entropy which accounts for 60 per cent of the systems, and a second broader peak around 130 keV cm2. We look for evolution over the 0.28-1.2 redshift range of the sample in density, pressure, entropy and cooling time at 0.015R500 and at 10 kpc radius. By modelling the evolution of the central quantities with a simple model, we find no evidence for a non-zero slope with redshift. In addition, a non-parametric sliding median shows no significant change. The fraction of cool-core clusters with central cooling times below 2 Gyr is consistent above and below z = 0.6 (˜30-40 per cent). Both by comparing the median thermodynamic profiles, centrally biased towards cool cores, in two redshift bins, and by modelling the evolution of the unbiased average profile as a function of redshift, we find no significant evolution beyond self-similar scaling in any of our examined quantities. Our average modelled radial density, entropy and cooling-time profiles appear as power laws with breaks around 0.2R500. The dispersion in these quantities rises inwards of this radius to around 0.4 dex, although some of this scatter can be fitted by a bimodal model.

Automated X-ray and Optical Analysis of the Virtual Observatory and Grid Computing

Science.gov (United States)

Ptak, A.; Krughoff, S.; Connolly, A.

2011-01-01

We are developing a system to combine the Web Enabled Source Identification with X-Matching (WESIX) web service, which emphasizes source detection on optical images,with the XAssist program that automates the analysis of X-ray data. XAssist is continuously processing archival X-ray data in several pipelines. We have established a workflow in which FITS images and/or (in the case of X ray data) an X-ray field can be input to WESIX. Intelligent services return available data (if requested fields have been processed) or submit job requests to a queue to be performed asynchronously. These services will be available via web services (for non-interactive use by Virtual Observatory portals and applications) and through web applications (written in the Django web application framework). We are adding web services for specific XAssist functionality such as determining .the exposure and limiting flux for a given position on the sky and extracting spectra and images for a given region. We are improving the queuing system in XAssist to allow for "watch lists" to be specified by users, and when X-ray fields in a user's watch list become publicly available they will be automatically added to the queue. XAssist is being expanded to be used as a survey planning 1001 when coupled with simulation software, including functionality for NuStar, eRosita, IXO, and the Wide Field Xray Telescope (WFXT), as part of an end to end simulation/analysis system. We are also investigating the possibility of a dedicated iPhone/iPad app for querying pipeline data, requesting processing, and administrative job control.

A Full Year's Chandra Exposure on Sloan Digital Sky Survey Quasars from the Chandra Multiwavelength Project

Science.gov (United States)

Green, Paul J.; Aldcroft, T. L.; Richards, G. T.; Barkhouse, W. A.; Constantin, A.; Haggard, D.; Karovska, M.; Kim, D.-W.; Kim, M.; Vikhlinin, A.; Anderson, S. F.; Mossman, A.; Kashyap, V.; Myers, A. D.; Silverman, J. D.; Wilkes, B. J.; Tananbaum, H.

2009-01-01

We study the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project. Our highest-confidence matched sample includes 1135 X-ray detected quasars in the redshift range 0.2 3, substantially expanding the known sample. We find no evidence for evolution out to z ~ 5 for either the X-ray photon index Γ or for the ratio of optical/UV to X-ray flux αox. About 10% of detected QSOs show best-fit intrinsic absorbing columns greater than 1022 cm-2, but the fraction might reach ~1/3 if most nondetections are absorbed. We confirm a significant correlation between αox and optical luminosity, but it flattens or disappears for fainter (MB gsim -23) active galactic nucleus (AGN) alone. We report significant hardening of Γ both toward higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in nonthermal X-ray emission, and our findings thereby strengthen analogies between Galactic black hole binaries and AGN. For uniformly selected subsamples of narrow-line Seyfert 1s and narrow absorption line QSOs, we find no evidence for unusual distributions of either αox or Γ.

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.;

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.

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.

JOINT ANALYSIS OF X-RAY AND SUNYAEV-ZEL'DOVICH OBSERVATIONS OF GALAXY CLUSTERS USING AN ANALYTIC MODEL OF THE INTRACLUSTER MEDIUM

Energy Technology Data Exchange (ETDEWEB)

Hasler, Nicole; Bulbul, Esra; Bonamente, Massimiliano; Landry, David [Department of Physics, University of Alabama, Huntsville, AL 35899 (United States); Carlstrom, John E.; Culverhouse, Thomas L.; Gralla, Megan; Greer, Christopher; Hennessy, Ryan; Leitch, Erik M.; Mantz, Adam; Marrone, Daniel P.; Plagge, Thomas [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Hawkins, David; Lamb, James W.; Muchovej, Stephen [Owens Valley Radio Observatory, California Institute of Technology, Big Pine, CA 93513 (United States); Joy, Marshall; Kolodziejczak, Jeffery [Space Science-VP62, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Miller, Amber [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Mroczkowski, Tony [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); and others

2012-04-01

We perform a joint analysis of X-ray and Sunyaev-Zel'dovich effect data using an analytic model that describes the gas properties of galaxy clusters. The joint analysis allows the measurement of the cluster gas mass fraction profile and Hubble constant independent of cosmological parameters. Weak cosmological priors are used to calculate the overdensity radius within which the gas mass fractions are reported. Such an analysis can provide direct constraints on the evolution of the cluster gas mass fraction with redshift. We validate the model and the joint analysis on high signal-to-noise data from the Chandra X-ray Observatory and the Sunyaev-Zel'dovich Array for two clusters, A2631 and A2204.

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.

M31 in the Chandra Era: A High Definition Movie of a Nearby Galaxy

Science.gov (United States)

Kong, Albert; di Stefano, Rosanne

2009-09-01

M31 has been a prime targets for all X-ray missions since the first detection in 1974. With its superb spatial resolution, Chandra is unique in resolving dense source regions and detecting faint sources. Since the launch of Chandra, M31 has been regularly observed. It is perhaps the only nearby galaxy which is observed by an X-ray telescope regularly throughout operation. With 10 years of observations, the center of M31 has been observed with Chandra for nearly 1 Msec. The X-ray skies of M31 not only consist of many transients and variables, globular cluster X-ray sources in M31 are also different from our Milky Way. They are in general more luminous and one of them may even host an intermediate-mass black hole. Supersoft and quasi-soft X-ray sources in M31 are the best kept secret to unlock the nature of the progenitor of Type Ia supernova. In this talk, I will review some of the important Chandra discoveries in M31 in the past 10 years.

Bayesian Multiscale Analysis of X-Ray Jet Features in High Redshift Quasars

Science.gov (United States)

McKeough, Kathryn; Siemiginowska, A.; Kashyap, V.; Stein, N.

2014-01-01

X-ray emission of powerful quasar jets may be a result of the inverse Compton (IC) process in which the Cosmic Microwave Background (CMB) photons gain energy by interactions with the jet’s relativistic electrons. However, there is no definite evidence that IC/CMB process is responsible for the observed X-ray emission of large scale jets. A step toward understanding the X-ray emission process is to study the Radio and X-ray morphologies of the jet. We implement a sophisticated Bayesian image analysis program, Low-count Image Reconstruction and Analysis (LIRA) (Esch et al. 2004; Conners & van Dyk 2007), to analyze jet features in 11 Chandra images of high redshift quasars (z ~ 2 - 4.8). Out of the 36 regions where knots are visible in the radio jets, nine showed detectable X-ray emission. We measured the ratios of the X-ray and radio luminosities of the detected features and found that they are consistent with the CMB radiation relationship. We derived a range of the bulk lorentz factor (Γ) for detected jet features under the CMB jet emission model. There is no discernible trend of Γ with redshift within the sample. The efficiency of the X-ray emission between the detected jet feature and the corresponding quasar also shows no correlation with redshift. This work is supported in part by the National Science Foundation REU and the Department of Defense ASSURE programs under NSF Grant no.1262851 and by the Smithsonian Institution, and by NASA Contract NAS8-39073 to the Chandra X-ray Center (CXC). This research has made use of data obtained from the Chandra Data Archive and Chandra Source Catalog, and software provided by the CXC in the application packages CIAO, ChIPS, and Sherpa. We thank Teddy Cheung for providing the VLA radio images. Connors, A., & van Dyk, D. A. 2007, Statistical Challenges in Modern Astronomy IV, 371, 101 Esch, D. N., Connors, A., Karovska, M., & van Dyk, D. A. 2004, ApJ, 610, 1213

A Comparison Between Spectral Properties of ULXs and Luminous X-ray Binaries

Science.gov (United States)

Berghea, C. T.; Colbert, E. J. M.; Roberts, T. P.

2004-05-01

What is special about the 1039 erg s-1 limit that is used to define the ULX class? We investigate this question by analyzing Chandra X-ray spectra of 71 X-ray bright point sources from nearby galaxies. Fifty-one of these sources are ULXs (LX(0.3-8.0 keV) ≥ 1039 erg s-1), and 20 sources (our comparison sample) are less-luminous X-ray binaries with LX(0.3-8.0 keV) = 1038-39 erg s-1. Our sample objects were selected from the Chandra archive to have ≥1000 counts and thus represent the highest quality spectra in the Chandra archives for extragalactic X-ray binaries and ULXs. We fit the spectra with one-component models (e.g., cold absorption with power-law, or cold absorption with multi-colored disk blackbody) and two-component models (e.g. absorption with both a power-law and a multi colored disk blackbody). A crude measure of the spectral states of the sources are determined observationally by calibrating the strength of the disk (blackbody) and coronal (power-law) components. These results are then use to determine if spectral properties of the ULXs are statistically distinct from those of the comparison objects, which are assumed to be ``normal'' black-hole X-ray binaries.

Characterization of the Optical and X-ray Properties of the Northwestern Wisps in the Crab Nebula

Science.gov (United States)

Weisskopf, M. C.; Bucciantini, N.; Idec, W.; Nillson, K.; Schweizer, T.; Tennant, A. F.; Zanin, R.

2013-01-01

We have studied the wisps to the northwest of the Crab pulsar as part of a multi-wavelength campaign in the visible and in X-rays. Optical observations were obtained using the Nordic Optical Telescope in La Palma and X-ray observations were made with the Chandra X-ray Observatory. The observing campaign took place from October 2010 until September 2012. About once per year we observe wisps forming and peeling off from (or near) the region commonly associated with the termination shock of the pulsar wind. We find that the exact locations of the northwestern wisps in the optical and in X-rays are similar but not coincident, with X-ray wisps preferentially located closer to the pulsar. This suggests that the optical and X-ray wisps are not produced by the same particle distribution. It is also interesting to note that the optical and radio wisps are also separated from each other (Bietenholz et al. 2004). Our measurements and their implications are interpreted in terms of a Doppler-boosted ring model that has its origin in MHD modeling. While the Doppler boosting factors inferred from the X-ray wisps are consistent with current MHD simulations of PWNe, the optical boosting factors are not, and typically exceed values from MHD simulations by about a factor of 4.

Advanced X-Ray Telescope Mirrors Provide Sharpest Focus Ever

Science.gov (United States)

1997-03-01

Performing beyond expectations, the high- resolution mirrors for NASA's most powerful orbiting X-ray telescope have successfully completed initial testing at Marshall Space Flight Center's X-ray Calibration Facility, Huntsville, AL. "We have the first ground test images ever generated by the telescope's mirror assembly, and they are as good as -- or better than -- expected," said Dr. Martin Weisskopf, Marshall's chief scientist for NASA's Advanced X-ray Astrophysics Facility (AXAF). The mirror assembly, four pairs of precisely shaped and aligned cylindrical mirrors, will form the heart of NASA's third great observatory. The X-ray telescope produces an image by directing incoming X-rays to detectors at a focal point some 30 feet beyond the telescope's mirrors. The greater the percentage of X-rays brought to focus and the smaller the size of the focal spot, the sharper the image. Tests show that on orbit, the mirror assembly of the Advanced X-ray Astrophysics Facility will be able to focus approximately 70 percent of X-rays from a source to a spot less than one-half arc second in radius. The telescope's resolution is equivalent to being able to read the text of a newspaper from half a mile away. "The telescope's focus is very clear, very sharp," said Weisskopf. "It will be able to show us details of very distant sources that we know are out there, but haven't been able to see clearly." In comparison, previous X-ray telescopes -- Einstein and Rosat -- were only capable of focusing X- rays to five arc seconds. The Advanced X-ray Telescope's resolving power is ten times greater. "Images from the new telescope will allow us to make major advances toward understanding how exploding stars create and disperse many of the elements necessary for new solar systems and for life itself," said Dr. Harvey Tananbaum, director of the Advanced X- ray Astrophysics Facility Science Center at the Smithsonian Astrophysical Observatory, in Cambridge, MA -- responsible for the telescope

Scientists Find X Rays from Stellar Winds That May Play Significant Role in Galactic Evolution

Science.gov (United States)

2001-09-01

Colorful star-forming regions that have captivated stargazers since the advent of the telescope 400 years ago contain gas thousands of times more energetic than previously recognized, powered by colliding stellar winds. This multimillion-degree gas radiated as X rays is one of the long-sought sources of energy and elements in the Milky Way galaxy's interstellar medium. A team led by Leisa Townsley, a senior research associate in astronomy and astrophysics at Penn State University, uncovered this wind phenomenon in the Rosette Nebula, a stellar nursery. With the Chandra X-ray Observatory, the team found that the most massive stars in the nebula produce winds that slam into each other, create violent shocks, and infuse the region with 6-million-degree gas. The findings are presented in Washington, D.C., today at a conference entitled "Two Years of Science with Chandra." "A ghostly glow of diffuse X-ray emission pervades the Rosette Nebula and perhaps many other similar star-forming regions throughout the Galaxy," said Townsley. "We now have a new view of the engine lighting the beautiful Rosette Nebula and new evidence for how the interstellar medium may be energized." Townsley and her colleagues created a striking X-ray panorama of the Rosette Molecular Cloud from four images with Chandra's Advanced CCD Imaging Spectrometer. This is a swath of the sky nearly 100 light years across sprayed with hundreds of X-ray-emitting young stars. In one corner of the Rosette Molecular Cloud lies the Rosette Nebula, called an "H II region" because the hydrogen gas there has been stripped of its electrons due to the strong ultraviolet radiation from its young stars. This region, about 5,000 light years away in the constellation Monoceros, the Unicorn, has long been a favorite among amateur astronomers. The wispy, colorful display is visible with small telescopes. The Chandra survey reveals, for the first time, 6-million-degree gas at the center of the Rosette Nebula, occupying a

X-ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest.

Science.gov (United States)

Otranto, Sebastian; Olson, Ronald; Beiersdorfer, Peter

2006-05-01

State selective nl-electron capture cross sections calculated using the classical trajectory Monte Carlo (CTMC) model are presented for highly charged ions with Z = 6-10 colliding with atoms and molecules. The energy dependence of the l-level populations is investigated. The calculated cross sections are compared with measurements made by Greenwood et al [1], using O^8+ and Ne^10+ on various targets at 3 keV/amu, and with recent x-ray emission cross sections measured with the EBIT machine at LLNL using O^8+ and Ne^9+,10+ on different targets at 10 eV/amu. We use the calculated cross sections to present an ab initio determination of the soft x-ray spectrum of comet C/Linear 1999 S4 that was observed on the Chandra X-ray Observatory [2]. [1] J. B. Greenwood, I. D. Williams, S. J. Smith and A. Chutjian, Phys. Rev. A 63, 062707 (2001). [2] C. M. Lisse, D. J. Christian, K. Dennerl, K. J. Meech, R. Petre, H. A. Weaver and S. J. Wolk, Science 292, 1343 (2001).

12 YEARS OF X-RAY VARIABILITY IN M31 GLOBULAR CLUSTERS, INCLUDING 8 BLACK HOLE CANDIDATES, AS SEEN BY CHANDRA

International Nuclear Information System (INIS)

Barnard, R.; Garcia, M.; Murray, S. S.

2012-01-01

We examined 134 Chandra observations of the population of X-ray sources associated with globular clusters (GCs) in the central region of M31. These are expected to be X-ray binary systems (XBs), consisting of a neutron star or black hole accreting material from a close companion. We created long-term light curves for these sources, correcting for background, interstellar absorption, and instrumental effects. We tested for variability by examining the goodness of fit for the best-fit constant intensity. We also created structure functions (SFs) for every object in our sample, the first time this technique has been applied to XBs. We found significant variability in 28 out of 34 GCs and GC candidates; the other 6 sources had 0.3-10 keV luminosities fainter than ∼2 × 10 36 erg s –1 , limiting our ability to detect similar variability. The SFs of XBs with 0.3-10 keV luminosities ∼2-50 × 10 36 erg s –1 generally showed considerably more variability than the published ensemble SF of active galactic nuclei (AGNs). Our brightest XBs were mostly consistent with the AGN SF; however, their 2-10 keV fluxes could be matched by <1 AGN per square degree. These encouraging results suggest that examining the long-term light curves of other X-ray sources in the field may provide an important distinction between X-ray binaries and background galaxies, as the X-ray emission spectra from these two classes of X-ray sources are similar. Additionally, we identify 3 new black hole candidates (BHCs) using additional XMM-Newton data, bringing the total number of M31 GC BHCs to 9, with 8 covered in this survey.

Chandra Finds Oxygen and Neon Ring in Ashes of Exploded Star

Science.gov (United States)

2000-01-01

NASA's Chandra X-ray Observatory has revealed an expanding ring-like structure of oxygen and neon that was hurled into space by the explosion of a massive star. The image of E0102-72 provides unprecedented details about the creation and dispersal of heavy elements necessary to form planets like Earth. The results were reported by Professor Claude Canizares of the Massachusetts Institute of Technology (MIT), Cambridge, at the 195th national meeting of the American Astronomical Society in Atlanta, Ga. Drs. Kathryn Flanagan, David Davis, and John Houck of MIT collaborated with Canizares in this investigation. E0102-72 is the remnant of a supernova explosion located in our neighbor galaxy, the Small Magellanic Cloud, nearly 200,000 light years away. It was created by the explosion of a star that was more than ten times as massive as our Sun. We are seeing the aftermath of the explosion a thousand or more years after the outburst. Shock waves are heating gas to temperatures of nearly 10 million degrees, so it glows with X-rays that are detected by Chandra's instruments. By using the High Energy Transmission Grating Spectrometer (HETG), astronomers were able to pinpoint the distribution of each chemical element individually and measure the velocities of different parts of the expanding ring. They also show the shock wave in a kind of "freeze-frame," revealing the progressive heating of the stellar matter as it plows into the surrounding gas. This is the first time such detailed X-ray information has ever been obtained for a supernova remnant, and should provide critical clues to the nature of supernovas. The grating spectrometer, which was built by an MIT team led by Canizares, spreads the X-rays according to their wavelength, giving distinct images of the object at specific wavelengths characteristic of each chemical element. Small wavelength shifts caused by the Doppler effect are used to measure the expansion velocities of each element independently. "We've been

Challenging the Forward Shock Model with the 80 Ms Follow up of the X-ray Afterglow of Gamma-Ray Burst 130427A

Directory of Open Access Journals (Sweden)

Massimiliano De Pasquale

2017-01-01

Full Text Available GRB 130427A was the most luminous gamma-ray burst detected in the last 30 years. With an isotropic energy output of 8.5 × 10 53 erg and redshift of 0.34, it combined very high energetics with a relative proximity to Earth in an unprecedented way. Sensitive X-ray observatories such as XMM-Newton and Chandra have detected the afterglow of this event for a record-breaking baseline longer than 80 million seconds. The light curve displays a simple power-law over more than three decades in time. In this presentation, we explore the consequences of this result for a few models put forward so far to interpret GRB 130427A, and more in general the implication of this outcome in the context of the standard forward shock model.

VizieR Online Data Catalog: ChaMP X-ray point source catalog (Kim+, 2007)

Science.gov (United States)

Kim, M.; Kim, D.-W.; Wilkes, B. J.; Green, P. J.; Kim, E.; Anderson, C. S.; Barkhouse, W. A.; Evans, N. R.; Ivezic, Z.; Karovska, M.; Kashyap, V. L.; Lee, M. G.; Maksym, P.; Mossman, A. E.; Silverman, J. D.; Tananbaum, H. D.

2009-01-01

We present the Chandra Multiwavelength Project (ChaMP) X-ray point source catalog with ~6800 X-ray sources detected in 149 Chandra observations covering ~10deg2. The full ChaMP catalog sample is 7 times larger than the initial published ChaMP catalog. The exposure time of the fields in our sample ranges from 0.9 to 124ks, corresponding to a deepest X-ray flux limit of f0.5-8.0=9x10-16ergs/cm2/s. The ChaMP X-ray data have been uniformly reduced and analyzed with ChaMP-specific pipelines and then carefully validated by visual inspection. The ChaMP catalog includes X-ray photometric data in eight different energy bands as well as X-ray spectral hardness ratios and colors. To best utilize the ChaMP catalog, we also present the source reliability, detection probability, and positional uncertainty. (10 data files).

Annealing bounds to prevent further Charge Transfer Inefficiency increase of the Chandra X-ray CCDs

Energy Technology Data Exchange (ETDEWEB)

Monmeyran, Corentin, E-mail: comonmey@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Patel, Neil S., E-mail: neilp@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Bautz, Mark W., E-mail: mwb@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Grant, Catherine E., E-mail: cgrant@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Prigozhin, Gregory Y., E-mail: gyp@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Agarwal, Anuradha, E-mail: anu@mit.edu [Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Kimerling, Lionel C., E-mail: lckim@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

2016-12-15

After the front-illuminated CCDs on board the X-ray telescope Chandra were damaged by radiation after launch, it was decided to anneal them in an effort to remove the defects introduced by the irradiation. The annealing led to an unexpected increase of the Charge Transfer Inefficiency (CTI). The performance degradation is attributed to point defect interactions in the devices. Specifically, the annealing at 30 °C activated the diffusion of the main interstitial defect in the device, the carbon interstitial, which led to its association with a substitutional impurity, ultimately resulting in a stable and electrically active defect state. Because the formation reaction of this carbon interstitial and substitutional impurity associate is diffusion limited, we recommend a higher upper bound for the annealing temperature and duration of any future CCD anneals, that of −50 °C for one day or −60 °C for a week, to prevent further CTI increase.

Development of the superconducting detectors and read-out for the X-IFU instrument on board of the X-ray observatory Athena

Energy Technology Data Exchange (ETDEWEB)

Gottardi, L., E-mail: l.gottardi@sron.nl [SRON Netherlands Institute for Space Research, Utrecht (Netherlands); Akamatsu, H.; Bruijn, M.P.; Hartog, R. den; Herder, J.-W. den; Jackson, B. [SRON Netherlands Institute for Space Research, Utrecht (Netherlands); Kiviranta, M. [VTT, Espoo (Finland); Kuur, J. van der; Weers, H. van [SRON Netherlands Institute for Space Research, Utrecht (Netherlands)

2016-07-11

The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3–12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum efficiency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-of-the art of the FDM read-out.

X-RAY PROPERTIES OF YOUNG EARLY-TYPE GALAXIES. I. X-RAY LUMINOSITY FUNCTION OF LOW-MASS X-RAY BINARIES

International Nuclear Information System (INIS)

Kim, Dong-Woo; Fabbiano, Giuseppina

2010-01-01

We have compared the combined X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXBs) detected in Chandra observations of young, post-merger elliptical galaxies with that of typical old elliptical galaxies. We find that the XLF of the 'young' sample does not present the prominent high-luminosity break at L X > 5 x 10 38 erg s -1 found in the old elliptical galaxy XLF. The 'young' and 'old' XLFs differ with a 3σ statistical significance (with a probability less than 0.2% that they derive from the same underlying parent distribution). Young elliptical galaxies host a larger fraction of luminous LMXBs (L X > 5 x 10 38 erg s -1 ) than old elliptical galaxies and the XLF of the young galaxy sample is intermediate between that of typical old elliptical galaxies and that of star-forming galaxies. This observational evidence may be related to the last major/minor mergers and the associated star formation.

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

Optical Counterparts for Low-Luminosity X-ray Sources in Omega Centauri

Science.gov (United States)

Cool, Adrienne

2002-07-01

We propose to use narrow-band HAlpha imaging with ACS to search for the optical counterparts of low-luminosity X-ray sources {Lx 2 x 10^30 - 5 x 10^32 erg/s} in the globular cluster Omega Centauri. With 9 WFC fields, we will cover the inner two core radii of the cluster, and encompass about 90 of the faint sources we have identified with Chandra. Approximately 30-50 of these sources should be cluster members, the remainder being mostly background galaxies plus a smaller number of foreground stars. This large population of low-Lx cluster X-ray sources is second only to the more than 100 faint sources recently discovered in 47 Tuc with Chandra {Grindlay et al. 2001a}, which have been identified as a mixture of cataclysmic variables, quiescent low-mass X-ray binaries, millisecond pulsars, and coronally active main-sequence binaries. Our Cycle 6 WFPC2 program successfully identified 2 of the 3 then-known faint X-ray sources in the core of Omega Cen using H-alpha imaging. We now propose to expand the areal coverage by a factor of about 18 to encompass the much larger number of sources that have since been discovered with Chandra. The extreme crowding in the central regions of Omega Cen requires the resolution of HST to obtain optical IDs. These identifications are key to making meaningful comparisons between the populations of faint X-ray sources in different clusters, in an effort to understand their origins and role in cluster dynamics.

THE CHANDRA VARIABLE GUIDE STAR CATALOG

International Nuclear Information System (INIS)

Nichols, Joy S.; Lauer, Jennifer L.; Morgan, Douglas L.; Sundheim, Beth A.; Henden, Arne A.; Huenemoerder, David P.; Martin, Eric

2010-01-01

Variable stars have been identified among the optical-wavelength light curves of guide stars used for pointing control of the Chandra X-ray Observatory. We present a catalog of these variable stars along with their light curves and ancillary data. Variability was detected to a lower limit of 0.02 mag amplitude in the 4000-10000 A range using the photometrically stable Aspect Camera on board the Chandra spacecraft. The Chandra Variable Guide Star Catalog (VGUIDE) contains 827 stars, of which 586 are classified as definitely variable and 241 are identified as possibly variable. Of the 586 definite variable stars, we believe 319 are new variable star identifications. Types of variables in the catalog include eclipsing binaries, pulsating stars, and rotating stars. The variability was detected during the course of normal verification of each Chandra pointing and results from analysis of over 75,000 guide star light curves from the Chandra mission. The VGUIDE catalog represents data from only about 9 years of the Chandra mission. Future releases of VGUIDE will include newly identified variable guide stars as the mission proceeds. An important advantage of the use of space data to identify and analyze variable stars is the relatively long observations that are available. The Chandra orbit allows for observations up to 2 days in length. Also, guide stars were often used multiple times for Chandra observations, so many of the stars in the VGUIDE catalog have multiple light curves available from various times in the mission. The catalog is presented as both online data associated with this paper and as a public Web interface. Light curves with data at the instrumental time resolution of about 2 s, overplotted with the data binned at 1 ks, can be viewed on the public Web interface and downloaded for further analysis. VGUIDE is a unique project using data collected during the mission that would otherwise be ignored. The stars available for use as Chandra guide stars are

A Deep X-ray Survey of the Globular Cluster Omega Centauri

Science.gov (United States)

Henleywillis, Simon; Cool, Adrienne M.; Haggard, Daryl; Heinke, Craig; Callanan, Paul; Zhao, Yue

2018-03-01

We identify 233 X-ray sources, of which 95 are new, in a 222 ks exposure of Omega Centauri with the Chandra X-ray Observatory's ACIS-I detector. The limiting unabsorbed flux in the core is fX(0.5-6.0 keV) ≃ 3×10-16 erg s-1 cm-2 (Lx ≃ 1×1030 erg s-1 at 5.2 kpc). We estimate that ˜60 ± 20 of these are cluster members, of which ˜30 lie within the core (rc = 155 arcsec), and another ˜30 between 1-2 core radii. We identify four new optical counterparts, for a total of 45 likely identifications. Probable cluster members include 18 cataclysmic variables (CVs) and CV candidates, one quiescent low-mass X-ray binary, four variable stars, and five stars that are either associated with ω Cen's anomalous red giant branch, or are sub-subgiants. We estimate that the cluster contains 40 ± 10 CVs with Lx > 1031 erg s-1, confirming that CVs are underabundant in ω Cen relative to the field. Intrinsic absorption is required to fit X-ray spectra of six of the nine brightest CVs, suggesting magnetic CVs, or high-inclination systems. Though no radio millisecond pulsars (MSPs) are currently known in ω Cen, more than 30 unidentified sources have luminosities and X-ray colours like those of MSPs found in other globular clusters; these could be responsible for the Fermi-detected gamma-ray emission from the cluster. Finally, we identify a CH star as the counterpart to the second-brightest X-ray source in the cluster and argue that it is a symbiotic star. This is the first such giant/white dwarf binary to be identified in a globular cluster.

X-ray astronomy

International Nuclear Information System (INIS)

Culhane, J.L.; Sanford, P.W.

1981-01-01

X-ray astronomy has been established as a powerful means of observing matter in its most extreme form. The energy liberated by sources discovered in our Galaxy has confirmed that collapsed stars of great density, and with intense gravitational fields, can be studied by making observations in the X-ray part of the electromagnetic spectrum. The astronomical objects which emit detectable X-rays include our own Sun and extend to quasars at the edge of the Universe. This book describes the history, techniques and results obtained in the first twenty-five years of exploration. Space rockets and satellites are essential for carrying the instruments above the Earth's atmosphere where it becomes possible to view the X-rays from stars and nebulae. The subject is covered in chapters, entitled: the birth of X-ray astronomy; the nature of X-radiation; X-rays from the Sun; solar-flare X-rays; X-rays from beyond the solar system; supernovae and their remnants; X-rays from binary stars; white dwarfs and neutron stars; black holes; X-rays from galaxies and quasars; clusters of galaxies; the observatories of the future. (author)

THE CHANDRA SOURCE CATALOG

International Nuclear Information System (INIS)

Evans, Ian N.; Primini, Francis A.; Glotfelty, Kenny J.; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G.; Grier, John D.; Hain, Roger M.; Harbo, Peter N.; He Xiangqun; Karovska, Margarita; Kashyap, Vinay L.; Davis, John E.; Houck, John C.; Hall, Diane M.

2010-01-01

The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed 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 first release of the CSC includes information about 94,676 distinct X-ray sources detected in a subset of public Advanced CCD Imaging Spectrometer imaging observations from roughly the first eight years of the Chandra mission. This release of the catalog includes point and compact sources with observed spatial extents ∼<30''. The catalog (1) provides access to the best estimates of the X-ray source properties for detected sources, with good scientific fidelity, and directly supports scientific analysis using the individual source data; (2) facilitates analysis of a wide range of statistical properties for classes of X-ray sources; and (3) provides efficient access to calibrated observational data and ancillary data products for individual X-ray sources, so that users can perform detailed further analysis using existing tools. The catalog includes real X-ray sources detected with flux estimates that are at least 3 times their estimated 1σ uncertainties in at least one energy band, while maintaining the number of spurious sources at a level of ∼<1 false source per field for a 100 ks observation. For each detected source, the CSC provides commonly tabulated quantities, including source position, extent, multi-band fluxes, hardness ratios, and variability statistics, derived from the observations in which the source is detected. In addition to these traditional catalog elements, for each X-ray source the CSC includes an extensive set of file-based data products that can be manipulated interactively, including source images, event lists, light curves, and spectra from each observation in which a

The Chandra Source Catalog

Science.gov (United States)

Evans, Ian N.; Primini, Francis A.; Glotfelty, Kenny J.; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Davis, John E.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G., II; Grier, John D.; Hain, Roger M.; Hall, Diane M.; Harbo, Peter N.; He, Xiangqun Helen; Houck, John C.; Karovska, Margarita; Kashyap, Vinay L.; Lauer, Jennifer; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph B.; Mitschang, Arik W.; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Nowak, Michael A.; Plummer, David A.; Refsdal, Brian L.; Rots, Arnold H.; Siemiginowska, Aneta; Sundheim, Beth A.; Tibbetts, Michael S.; Van Stone, David W.; Winkelman, Sherry L.; Zografou, Panagoula

2010-07-01

The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed 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 first release of the CSC includes information about 94,676 distinct X-ray sources detected in a subset of public Advanced CCD Imaging Spectrometer imaging observations from roughly the first eight years of the Chandra mission. This release of the catalog includes point and compact sources with observed spatial extents lsim30''. The catalog (1) provides access to the best estimates of the X-ray source properties for detected sources, with good scientific fidelity, and directly supports scientific analysis using the individual source data; (2) facilitates analysis of a wide range of statistical properties for classes of X-ray sources; and (3) provides efficient access to calibrated observational data and ancillary data products for individual X-ray sources, so that users can perform detailed further analysis using existing tools. The catalog includes real X-ray sources detected with flux estimates that are at least 3 times their estimated 1σ uncertainties in at least one energy band, while maintaining the number of spurious sources at a level of lsim1 false source per field for a 100 ks observation. For each detected source, the CSC provides commonly tabulated quantities, including source position, extent, multi-band fluxes, hardness ratios, and variability statistics, derived from the observations in which the source is detected. In addition to these traditional catalog elements, for each X-ray source the CSC includes an extensive set of file-based data products that can be manipulated interactively, including source images, event lists, light curves, and spectra from each observation in which a

Rapid X-Ray Variations of the Geminga Pulsar Wind Nebula

Energy Technology Data Exchange (ETDEWEB)

Hui, C. Y.; Lee, Jongsu [Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134 (Korea, Republic of); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China); Tam, P. H. T. [School of Physics and Astronomy, Sun Yat-Sen University, Guangzhou 510275 (China); Takata, J. [Institute of Particle Physics and Astronomy, Huazhong University of Science and Technology, Wuhan (China); Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Ryu, Dongsu, E-mail: cyhui@cnu.ac.kr [Department of Physics, UNIST, Ulsan 44919 (Korea, Republic of)

2017-09-10

A recent study by Posselt et al. reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using Chandra X-ray Observatory . In comparison with previous studies of this system, a number of new findings have been reported, and we found that these suggest the possible variabilities in various components of this PWN. This motivates us to carry out a dedicated search for the morphological and spectral variations of this complex nebula. We have discovered variabilities on timescales from a few days to a few months from different components of the nebula. The fastest change occurred in the circumstellar environment at a rate of 80% of the speed of light. One of the most spectacular results is the wiggling of a half light-year long tail as an extension of the jet, which is significantly bent by the ram pressure. The jet wiggling occurred at a rate of about 20% of the speed of light. This twisted structure could possibly be a result of a propagating torsional Alfv́en wave. We have also found evidence of spectral hardening along this tail for a period of about nine months.

BeppoSAX and Chandra Observations of SAX J0103.2-7209 = 2E 0101.5-7225: A New Persistent 345 Second X-Ray Pulsar in the Small Magellanic Cloud.

Science.gov (United States)

Israel; Campana; Covino; Dal Fiume D; Gaetz; Mereghetti; Oosterbroek; Orlandini; Parmar; Ricci; Stella

2000-03-10

We report the results of a 1998 July BeppoSAX observation of a field in the Small Magellanic Cloud which led to the discovery of approximately 345 s pulsations in the X-ray flux of SAX J0103.2-7209. The BeppoSAX X-ray spectrum is well fitted by an absorbed power law with a photon index of approximately 1.0 plus a blackbody component with kT=0.11 keV. The unabsorbed luminosity in the 2-10 keV energy range is approximately 1.2x1036 ergs s-1. In a very recent Chandra observation, the 345 s pulsations are also detected. The available period measurements provide a constant period derivative of -1.7 s yr-1 over the last 3 years, making SAX J0103.2-7209 one of the most rapidly spinning up X-ray pulsars known. The BeppoSAX position (30&arcsec; uncertainty radius) is consistent with that of the Einstein source 2E 0101.5-7225 and the ROSAT source RX J0103.2-7209. This source was detected at a luminosity level of a few times 1035-1036 ergs s-1 in all data sets of past X-ray missions since 1979. The ROSAT HRI and Chandra positions are consistent with that of a mV=14.8 Be spectral-type star already proposed as the likely optical counterpart of 2E 0101.5-7225. We briefly report and discuss photometric and spectroscopic data carried out at the ESO telescopes 2 days before the BeppoSAX observation. We conclude that SAX J0103.2-7209 and 2E 0101.5-7225 are the same source: a relatively young and persistent X-ray pulsar in the SMC.

X-Ray Properties of AGN in Brightest Cluster Galaxies. I. A Systematic Study of the Chandra Archive in the 0.2 < z < 0.3 and 0.55 < z < 0.75 Redshift Range

Science.gov (United States)

Yang, Lilan; Tozzi, Paolo; Yu, Heng; Lusso, Elisabeta; Gaspari, Massimo; Gilli, Roberto; Nardini, Emanuele; Risaliti, Guido

2018-05-01

We present a search for nuclear X-ray emission in the brightest cluster galaxies (BCGs) of a sample of groups and clusters of galaxies extracted from the Chandra archive. The exquisite angular resolution of Chandra allows us to obtain robust photometry at the position of the BCG, and to firmly identify unresolved X-ray emission when present, thanks to an accurate characterization of the extended emission at the BCG position. We consider two redshift bins (0.2 soft (0.5–2 keV) or hard (2–7 keV) band is detected only in 14 and 9 BCGs (∼18% of the total samples), respectively. The X-ray photometry shows that at least half of the BCGs have a high hardness ratio, compatible with significant intrinsic absorption. This is confirmed by the spectral analysis with a power-law model plus intrinsic absorption. We compute the fraction of X-ray bright BCGs above a given hard X-ray luminosity, considering only sources with positive photometry in the hard band (12/5 sources in the low/high-z sample).

Chandra Studies of Planets and Comets in the X-ray

Science.gov (United States)

Lisse, Carey; Bhardwaj, A.; Wolk, S. J.; Christian, D. J.; Dennerl, K.; Bodewits, D.; Zurbuchen, T. H.

2009-09-01

The discovery of high energy x-ray emission in 1996 from C/1996 B2 (Hyakutake) created a new class of solar system x-ray emitting objects [1]. Subsequent detections of the morphology, spectra, and time dependence of the x-rays from more than 20 comets have shown that the very soft (E Lisse et al., Science 274, 205 (1996)[2] R. Wegmann and K. Dennerl, A&A 430, L33 (2005)[3] D. Bodewits et al., A&A 469, 1183 (2007)[4] A. Bhardwaj et al., PSS 55, 1135 - 1189 (2007)

The Chandra HRC View of the Subarcsecond Structures in the Nuclear Region of NGC 1068

Science.gov (United States)

Wang, Junfeng; Fabbiano, Giuseppina; Karovska, Margarita; Elvis, Martin; Risaliti, Guido

2012-09-01

We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsec radius region of this galaxy. The HRC image resolves the narrow-line region into X-ray emission clumps matching bright emission-line clouds in the HST [OIII] λ5007 images and allows comparison with subarcsecond-scale radio jet for the first time. Two distinct X-ray knots are revealed at 1.3-1.4 arcsec northeast and southwest of the nucleus. Based on the combined X-ray, [O III], and radio continuum morphology, we identify the locations of intense radio jet-cloud interaction. The [O III] to soft X-ray ratios show that some of these clouds are strongly affected by shock heating, whereas in other locations the jet simply thrusts through with no signs of strong interaction. This is further strengthened by the presence of a kT ~ 1 keV collisionally ionized component in the ACIS spectrum of a shock-heated cloud HST-G. We estimate that the kinematic luminosity of the jet-driven shocks is 6 × 1038 erg s-1, a negligible fraction (10-4) of the estimated total jet power.

VizieR Online Data Catalog: Cool-core clusters with Chandra obs. (Andrade-Santos+, 2017)

Science.gov (United States)

Andrade-Santos, F.; Jones, C.; Forman, W. R.; Lovisari, L.; Vikhlinin, A.; van Weeren, R. J.; Murray, S. S.; Arnaud, M.; Pratt, G. W.; Democles, J.; Kraft, R.; Mazzotta, P.; Bohringer, H.; Chon, G.; Giacintucci, S.; Clarke, T. E.; Borgani, S.; David, L.; Douspis, M.; Pointecouteau, E.; Dahle, H.; Brown, S.; Aghanim, N.; Rasia, E.

2018-02-01

The main goal of this work is to compare the fraction of cool-core (CC) clusters in X-ray-selected and SZ-selected samples. The first catalog of 189 SZ clusters detected by the Planck mission was released in early 2011 (Planck Collaboration 2011, VIII/88/esz). A Chandra XVP (X-ray Visionary Program--PI: Jones) and HRC Guaranteed Time Observations (PI: Murray) combined to form the Chandra-Planck Legacy Program for Massive Clusters of Galaxies. For each of the 164 ESZ Planck clusters at z<=0.35, we obtained Chandra exposures sufficient to collect at least 10000 source counts. The X-ray sample used here is an extension of the Voevodkin & Vikhlinin (2004ApJ...601..610V) sample. This sample contains 100 clusters and has an effective redshift depth of z<0.3. All have Chandra observations. Of the 100 X-ray-selected clusters, 49 are also in the ESZ sample, and 47 are in the HIFLUGCS (Reiprich & Boehringer 2002ApJ...567..716R) catalog. (2 data files).

Searching for Exoplanet Effects on the X-ray Spectrum of τ Boo

Science.gov (United States)

Wood, Brian; Laming, J. Martin

2018-01-01

We study the X-ray spectrum of the exoplanet host star τ Boo A (F7 V), in order to explore the possibility that its very close-in, massive exoplanet (Porb=3.31 days, m sin i=3.9 MJ) may be affecting the coronal emissions of this star. The star was observed recently by Chandra/LETGS for 92 ksec in three pieces between 2017 February 27 and 2017 March 5; and was previously observed by XMM for 65 ksec in 2003 June 24. The new Chandra observations allow us to resolve τ Boo A from its stellar companion, τ Boo B (M2 V), for the first time. The companion accounts for 21% of the system's total X-ray emission at the time of the Chandra observation. Nevertheless, our measurements of τ Boo A emission measures and coronal abundances from Chandra are reasonably consistent with previous measurements from XMM by Maggio et al. (2011, A&A, 527, A144), in which τ Boo A and B are not resolved. Covering planetary orbital phases 0.21-0.31, 0.44-0.49, and 0.69-0.86, the Chandra data show that τ Boo A's coronal X-ray spectrum does not vary significantly with planetary orbital phase. However, our analysis suggests that coronal abundances for τ Boo A are somewhat anomalous, with a significantly weaker "FIP effect" compared to similar stars without close-in exoplanets, particularly π3 Ori (F6 V).

Fermi Non-detections of Four X-Ray Jet Sources and Implications for the IC/CMB Mechanism

Science.gov (United States)

Breiding, Peter; Meyer, Eileen T.; Georganopoulos, Markos; Keenan, M. E.; DeNigris, N. S.; Hewitt, Jennifer

2017-11-01

Since its launch in 1999, the Chandra X-ray observatory has discovered several dozen X-ray jets associated with powerful quasars. In many cases, the X-ray spectrum is hard and appears to come from a second spectral component. The most popular explanation for the kpc-scale X-ray emission in these cases has been inverse-Compton (IC) scattering of Cosmic Microwave Background (CMB) photons by relativistic electrons in the jet (the IC/CMB model). Requiring the IC/CMB emission to reproduce the observed X-ray flux density inevitably predicts a high level of gamma-ray emission, which should be detectable with the Fermi Large Area Telescope (LAT). In previous work, we found that gamma-ray upper limits from the large-scale jets of 3C 273 and PKS 0637-752 violate the predictions of the IC/CMB model. Here, we present Fermi/LAT flux density upper limits for the X-ray jets of four additional sources: PKS 1136-135, PKS 1229-021, PKS 1354+195, and PKS 2209+080. We show that these limits violate the IC/CMB predictions at a very high significance level. We also present new Hubble Space Telescope observations of the quasar PKS 2209+080 showing a newly detected optical jet, and Atacama Large Millimeter/submillimeter Array band 3 and 6 observations of all four sources, which provide key constraints on the spectral shape that enable us to rule out the IC/CMB model.

EMISSION LINES BETWEEN 1 AND 2 keV IN COMETARY X-RAY SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Ewing, Ian; Christian, Damian J. [Department of Physics and Astronomy, California State University, 18111 Nordhoff Street, Northridge, CA 91330 (United States); Bodewits, Dennis [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Dennerl, Konrad [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85741 Garching Germany (Germany); Lisse, Carey M. [Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723 (United States); Wolk, Scott J., E-mail: ian.ewing.794@my.csun.edu, E-mail: daman.christian@csun.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-01-20

We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.

The Chandra Source Catalog 2.0: Calibrations

Science.gov (United States)

Graessle, Dale E.; Evans, Ian N.; Rots, Arnold H.; Allen, Christopher E.; Anderson, Craig S.; Budynkiewicz, Jamie A.; Burke, Douglas; Chen, Judy C.; Civano, Francesca Maria; D'Abrusco, Raffaele; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Gibbs, Danny G., II; Glotfelty, Kenny J.; 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.; 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; Siemiginowska, Aneta; Sundheim, Beth A.; Tibbetts, Michael; Van Stone, David W.; Zografou, Panagoula

2018-01-01

Among the many enhancements implemented for the release of Chandra Source Catalog (CSC) 2.0 are improvements in the processing calibration database (CalDB). We have included a thorough overhaul of the CalDB software used in the processing. The software system upgrade, called "CalDB version 4," allows for a more rational and consistent specification of flight configurations and calibration boundary conditions. Numerous improvements in the specific calibrations applied have also been added. Chandra's radiometric and detector response calibrations vary considerably with time, detector operating temperature, and position on the detector. The CalDB has been enhanced to provide the best calibrations possible to each observation over the fifteen-year period included in CSC 2.0. Calibration updates include an improved ACIS contamination model, as well as updated time-varying gain (i.e., photon energy) and quantum efficiency maps for ACIS and HRC-I. Additionally, improved corrections for the ACIS quantum efficiency losses due to CCD charge transfer inefficiency (CTI) have been added for each of the ten ACIS detectors. These CTI corrections are now time and temperature-dependent, allowing ACIS to maintain a 0.3% energy calibration accuracy over the 0.5-7.0 keV range for any ACIS source in the catalog. Radiometric calibration (effective area) accuracy is estimated at ~4% over that range. We include a few examples where improvements in the Chandra CalDB allow for improved data reduction and modeling for the new CSC.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.

X-ray binaries, part 1

International Nuclear Information System (INIS)

Hammerschlag-Hensberge, G.C.M.J.

1977-01-01

Optical observations of X-ray binaries and their interpretation are described. A number of early-type stars which are identified as companions of X-ray sources are photometrically and spectroscopically observed. The spectra were obtained with the coude spectrograph attached to the 1.5 m telescope of the European Southern Observatory, La Silla, Chile. Registrations of the spectra were made with the Faul-Coradi microphotometer of the Observatory at Utrecht. To study radial velocity variations, the positions of the spectral lines were measured with the Grant comparator of the University of Groningen

Chandra, NuSTAR and NICER Observations of MAXI J1535-571

Science.gov (United States)

Neilsen, Joseph; Cackett, Ed; Fabian, Andy; Gendreau, Keith C.; Miller, Jon M.; Pasham, Dheeraj; Remillard, Ron; Steiner, Jack; Uttley, Phil

2018-01-01

In September 2017, MAXI detected an outburst of a previously-unknown transient, MAXI J1535-571. Subsequent radio and X-ray monitoring indicated that the source is a strong black hole candidate. We began a series of monitoring observations with Chandra HETGS, NuSTAR, and NICER to track the evolution of the outburst. Together, these three observatories represent an incredible opportunity to study the geometry of the accretion flow (via continuum spectroscopy), its variation with accretion state (via spectral variability), and any associated outflows or mass ejections (via line spectroscopy). We will present our analysis of this bright outburst and discuss the physics of accretion and ejection in this new black hole candidate.

Adjustable Grazing Incidence X-ray Optics with 0.5 Arc Second Resolution

Science.gov (United States)

Reid, Paul

We seek to develop adjustable grazing incidence optics for x-ray astronomy. The goal of this development is thin, lightweight mirrors with angular resolution of 0.5 arc seconds, comparable to the Chandra X-ray Observatory. The new mirror design consists of thin segments of a Wolter-I grazing incidence mirror, with piezo-electric material deposited directly on the back surface of the mirror. Depositing a pattern of independently addressable electrodes on top of the piezoelectric material produces an array of independent piezo cells. Energizing a particular cell introduces a localized deformation in the mirror without the need for a reaction structure. By applying the appropriate voltage to the piezo cells, it is possible to correct mirror figure errors that result from mirror fabrication, gravity release, mounting, and thermal effects. Because the thin mirrors segments are lightweight, they can be densely nested to produce collecting area thirty times that of Chandra, on an affordably priced mission. This Supporting Technology program is a follow-on to an existing APRA program. In the existing program we demonstrated the first successful deposition of piezoelectric material on thermally formed glass substrates. We showed that the localized deformations produced by the piezo cells match finite element predictions, and the piezo cell adjustment range meets requirements necessary to achieve the desired figure correction. We have also shown through simulation that representative mirror figure errors can be corrected via modeled influence functions to achieve 0.5 arc sec imaging performance. This provides a firm foundation on which to develop further the technology. We will continue to optimize the deposition of thin piezoelectric films onto thermally formed glass and electroplated metal mirror segments to improve yield and manufacturability. We will deposit piezoelectric material onto conical mirror segments and demonstrate figure correction in agreement with prediction

The X-ray Variability of Eta Car, 1996-2010

Science.gov (United States)

Corcoran, Michael F.; Hamaguchi, K.; Gull, T.; Owocki, S.; Pittard, J.

2010-01-01

X-ray photometry in the 2-10 keY band of the the supermassive binary star Eta Car has been measured with the Rossi X-ray Timing Explorer from 1996-2010. The ingress to X-ray minimum is consistent with a period of 2024 days. The 2009 X-ray minimum began on January 162009 and showed an unexpectedly abrupt recovery starting after 12 Feb 2009. The X-ray colors become harder about half-way through all three minima and continue until flux recovery. The behavior of the fluxes and X-ray colors for the most recent X-ray minimum, along with Chandra high resolution grating spectra at key phases suggests a significant change in the inner wind of Eta Car, a possible indicator that the star is entering a new unstable phase of mass loss.

THE SPECTACULAR RADIO-NEAR-IR-X-RAY JET OF 3C 111: THE X-RAY EMISSION MECHANISM AND JET KINEMATICS

Energy Technology Data Exchange (ETDEWEB)

Clautice, Devon; Perlman, Eric S. [Department of Physics and Space Sciences, Florida Institute of Technology, 150 W. University Boulevard, Melbourne, FL 32901 (United States); Georganopoulos, Markos [Department of Physics, University of Maryland—Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Lister, Matthew L.; Hogan, Brandon [Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Tombesi, Francesco [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Cara, Mihai [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Marshall, Herman L. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Kazanas, Demos [NASA’s Goddard Space Flight Center, Astrophysics Science Division, Code 663, Greenbelt, MD 20771 (United States)

2016-08-01

Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma-rays and carry copious amounts of matter and energy from the sub-parsec central regions out to the kiloparsec and often megaparsec scale galaxy and cluster environs. While most spatially resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near-IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. We discuss new, deep Chandra and Hubble Space Telescope ( HST ) observations that reveal both near-IR and X-ray emission from several components of the 3C 111 jet, as well as both the northern and southern hotspots. Important differences are seen between the morphologies in the radio, X-ray, and near-IR bands. The long (over 100 kpc on each side), straight nature of this jet makes it an excellent prototype for future, deep observations, as it is one of the longest such features seen in the radio, near-IR/optical, and X-ray bands. Several independent lines of evidence, including the X-ray and broadband spectral shape as well as the implied velocity of the approaching hotspot, lead us to strongly disfavor the EC/CMB model and instead favor a two-component synchrotron model to explain the observed X-ray emission for several jet components. Future observations with NuSTAR , HST , and Chandra will allow us to further constrain the emission mechanisms.

Tidal disruption of stars by supermassive black holes: The X-ray view

Directory of Open Access Journals (Sweden)

Komossa S.

2012-12-01

Full Text Available The tidal disruption of stars by supermassive black holes produces luminous soft X-ray accretion flares in otherwise inactive galaxies. First events have been discovered in X-rays with the ROSAT observatory, and have more recently been detected with XMM-Newton, Chandra and Swift, and at other wavelengths. In X-rays, they typically appear as very soft, exceptionally luminous outbursts of radiation, which decline consistent with L ∝ t−5/3 on the timescale of months to years. They reach total amplitudes of decline up to factors 1000–6000 more than a decade after their initial high-states, and in low-state, their host galaxies are essentially X-ray inactive, optically inactive, and radio inactive. X-ray luminous tidal disruption events (TDEs represent a powerful new probe of accretion physics near the event horizon, and of relativistic effects. TDEs offer a new way of estimating black hole spin, and they are signposts of supermassive binary black holes and recoiling black holes. Once discovered in the thousands in upcoming sky surveys, their rates will probe stellar dynamics in distant galaxies, and they will uncover the – so far elusive – population of intermediate mass black holes in the universe, if they do exist. Further, the reprocessing of the flare into IR, optical and UV emission lines provides us with multiple new diagnostics of the properties of any gaseous material in the vicinity of the black hole (including the disrupted star itself and in the host galaxy. First candidate events of this kind have been reported recently.

A Comprehensive Spectral Analysis of the X-Ray Pulsar 4U 1907+09 from Two Observations with the Suzaku X-Ray Observatory

Science.gov (United States)

Rivers, Elizabeth; Markowitz, Alex; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Furst, Felix; Suchy, Slawomir; Kreykenbohm, Ingo; Wilms, Jorn; Rothschild, Richard

2009-01-01

We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku observatory, The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx. 19 keV. Additionally, using the narrow CCD response of Suzaku near 6 ke V allows us to study in detail the Fe K bandpass and to quantify the Fe Kp line for this source for the first time. The source is absorbed by fully-covering material along the line of sight with a column density of N(sub H) approx. 2 x 10(exp 22)/sq cm, consistent with a wind accreting geometry, and a high Fe abundance (approx. 3 - 4 x solar). Time and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in NH along the line of sight, perhaps indicating clumpiness in the stellar wind

FINDING FOSSIL GROUPS: OPTICAL IDENTIFICATION AND X-RAY CONFIRMATION

Energy Technology Data Exchange (ETDEWEB)

Miller, Eric D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Rykoff, Eli S. [E.O. Lawrence Berkeley National Lab, 1 Cyclotron Rd., Berkeley, CA 94720 (United States); Dupke, Renato A. [Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109 (United States); Mendes de Oliveira, Claudia; Proctor, Robert N. [Departamento de Astronomia, Instituto de Astronomia, Geofisica e Ciencias Atmosfericas da Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-090 Sao Paulo (Brazil); Lopes de Oliveira, Raimundo [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, 13560-970 Sao Carlos, SP (Brazil); Garmire, Gordon P. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Koester, Benjamin P. [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States); McKay, Timothy A., E-mail: milleric@mit.edu [Department of Physics, University of Michigan, 450 Church St., Ann Arbor, MI 48109 (United States)

2012-03-10

We report the discovery of 12 new fossil groups (FGs) of galaxies, systems dominated by a single giant elliptical galaxy and cluster-scale gravitational potential, but lacking the population of bright galaxies typically seen in galaxy clusters. These FGs, selected from the maxBCG optical cluster catalog, were detected in snapshot observations with the Chandra X-ray Observatory. We detail the highly successful selection method, with an 80% success rate in identifying 12 FGs from our target sample of 15 candidates. For 11 of the systems, we determine the X-ray luminosity, temperature, and hydrostatic mass, which do not deviate significantly from expectations for normal systems, spanning a range typical of rich groups and poor clusters of galaxies. A small number of detected FGs are morphologically irregular, possibly due to past mergers, interaction of the intra-group medium with a central active galactic nucleus (AGN), or superposition of multiple massive halos. Two-thirds of the X-ray-detected FGs exhibit X-ray emission associated with the central brightest cluster galaxy (BCG), although we are unable to distinguish between AGN and extended thermal galaxy emission using the current data. This sample representing a large increase in the number of known FGs, will be invaluable for future planned observations to determine FG temperature, gas density, metal abundance, and mass distributions, and to compare to normal (non-fossil) systems. Finally, the presence of a population of galaxy-poor systems may bias mass function determinations that measure richness from galaxy counts. When used to constrain power spectrum normalization and {Omega}{sub m}, these biased mass functions may in turn bias these results.

Statistical Characterization of the Chandra Source Catalog

Science.gov (United States)

Primini, Francis A.; Houck, John C.; Davis, John E.; Nowak, Michael A.; Evans, Ian N.; Glotfelty, Kenny J.; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G.; Grier, John D.; Hain, Roger M.; Hall, Diane M.; Harbo, Peter N.; He, Xiangqun Helen; Karovska, Margarita; Kashyap, Vinay L.; Lauer, Jennifer; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph B.; Mitschang, Arik W.; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Plummer, David A.; Refsdal, Brian L.; Rots, Arnold H.; Siemiginowska, Aneta; Sundheim, Beth A.; Tibbetts, Michael S.; Van Stone, David W.; Winkelman, Sherry L.; Zografou, Panagoula

2011-06-01

The first release of the Chandra Source Catalog (CSC) contains ~95,000 X-ray sources in a total area of 0.75% of the entire sky, using data from ~3900 separate ACIS observations of a multitude of different types of X-ray sources. In order to maximize the scientific benefit of such a large, heterogeneous data set, careful characterization of the statistical properties of the catalog, i.e., completeness, sensitivity, false source rate, and accuracy of source properties, is required. Characterization efforts of other large Chandra catalogs, such as the ChaMP Point Source Catalog or the 2 Mega-second Deep Field Surveys, while informative, cannot serve this purpose, since the CSC analysis procedures are significantly different and the range of allowable data is much less restrictive. We describe here the characterization process for the CSC. This process includes both a comparison of real CSC results with those of other, deeper Chandra catalogs of the same targets and extensive simulations of blank-sky and point-source populations.

The Einstein Observatory catalog of IPC x ray sources. Volume 1E: Documentation

Science.gov (United States)

Harris, D. E.; Forman, W.; Gioia, I. M.; Hale, J. A.; Harnden, F. R., Jr.; Jones, C.; Karakashian, T.; Maccacaro, T.; Mcsweeney, J. D.; Primini, F. A.

1993-01-01

The Einstein Observatory (HEAO-2, launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics, which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images. The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentation describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers, and data useful for calculating upper limits and fluxes.

Formation and Evolution of X-ray Binaries

Science.gov (United States)

Fragkos, Anastasios

X-ray binaries - mass-transferring binary stellar systems with compact object accretors - are unique astrophysical laboratories. They carry information about many complex physical processes such as star formation, compact object formation, and evolution of interacting binaries. My thesis work involves the study of the formation and evolution of Galactic and extra-galacticX-ray binaries using both detailed and realistic simulation tools, and population synthesis techniques. I applied an innovative analysis method that allows the reconstruction of the full evolutionary history of known black hole X-ray binaries back to the time of compact object formation. This analysis takes into account all the available observationally determined properties of a system, and models in detail four of its evolutionary evolutionary phases: mass transfer through the ongoing X-ray phase, tidal evolution before the onset of Roche-lobe overflow, motion through the Galactic potential after the formation of the black hole, and binary orbital dynamics at the time of core collapse. Motivated by deep extra-galactic Chandra survey observations, I worked on population synthesis models of low-mass X-ray binaries in the two elliptical galaxies NGC3379 and NGC4278. These simulations were targeted at understanding the origin of the shape and normalization of the observed X-ray luminosity functions. In a follow up study, I proposed a physically motivated prescription for the modeling of transient neutron star low-mass X-ray binary properties, such as duty cycle, outburst duration and recurrence time. This prescription enabled the direct comparison of transient low-mass X-ray binary population synthesis models to the Chandra X-ray survey of the two ellipticals NGC3379 and NGC4278. Finally, I worked on population synthesismodels of black holeX-ray binaries in the MilkyWay. This work was motivated by recent developments in observational techniques for the measurement of black hole spin magnitudes in

Detecting edges in the X-ray surface brightness of galaxy clusters

Science.gov (United States)

Sanders, J. S.; Fabian, A. C.; Russell, H. R.; Walker, S. A.; Blundell, K. M.

2016-08-01

The effects of many physical processes in the intracluster medium of galaxy clusters imprint themselves in X-ray surface brightness images. It is therefore important to choose optimal methods for extracting information from and enhancing the interpretability of such images. We describe in detail a gradient filtering edge detection method that we previously applied to images of the Centaurus cluster of galaxies. The Gaussian gradient filter measures the gradient in the surface brightness distribution on particular spatial scales. We apply this filter on different scales to Chandra X-ray observatory images of two clusters with active galactic nucleus feedback, the Perseus cluster and M 87, and a merging system, A 3667. By combining filtered images on different scales using radial filters spectacular images of the edges in a cluster are produced. We describe how to assess the significance of features in filtered images. We find the gradient filtering technique to have significant advantages for detecting many kinds of features compared to other analysis techniques, such as unsharp masking. Filtering cluster images in this way in a hard energy band allows shocks to be detected.

New Constraints on the Geometry and Kinematics of Matter Surrounding the Accretion Flow in X-Ray Binaries from Chandra High-energy Transmission Grating X-Ray Spectroscopy

Science.gov (United States)

Tzanavaris, P.; Yaqoob, T.

2018-03-01

The narrow, neutral Fe Kα fluorescence emission line in X-ray binaries (XRBs) is a powerful probe of the geometry, kinematics, and Fe abundance of matter around the accretion flow. In a recent study it has been claimed, using Chandra High-Energy Transmission Grating (HETG) spectra for a sample of XRBs, that the circumnuclear material is consistent with a solar-abundance, uniform, spherical distribution. It was also claimed that the Fe Kα line was unresolved in all cases by the HETG. However, these conclusions were based on ad hoc models that did not attempt to relate the global column density to the Fe Kα line emission. We revisit the sample and test a self-consistent model of a uniform, spherical X-ray reprocessor against HETG spectra from 56 observations of 14 Galactic XRBs. We find that the model is ruled out in 13/14 sources because a variable Fe abundance is required. In two sources a spherical distribution is viable, but with nonsolar Fe abundance. We also applied a solar-abundance Compton-thick reflection model, which can account for the spectra that are inconsistent with a spherical model, but spectra with a broader bandpass are required to better constrain model parameters. We also robustly measured the velocity width of the Fe Kα line and found FWHM values of up to ∼5000 km s‑1. Only in some spectra was the Fe Kα line unresolved by the HETG.

New Constraints on the Geometry and Kinematics of Matter Surrounding the Accretion Flow in X-Ray Binaries from Chandra High-Energy Transmission Grating X-Ray Spectroscopy

Science.gov (United States)

Tzanavaris, P.; Yaqoob, T.

2018-01-01

The narrow, neutral Fe Ka fluorescence emission line in X-ray binaries (XRBs) is a powerful probe of the geometry, kinematics, and Fe abundance of matter around the accretion flow. In a recent study it has been claimed, using Chandra High-Energy Transmission Grating (HETG) spectra for a sample of XRBs, that the circumnuclear material is consistent with a solar-abundance, uniform, spherical distribution. It was also claimed that the Fe Ka line was unresolved in all cases by the HETG. However, these conclusions were based on ad hoc models that did not attempt to relate the global column density to the Fe Ka line emission. We revisit the sample and test a self-consistent model of a uniform, spherical X-ray reprocessor against HETG spectra from 56 observations of 14 Galactic XRBs. We find that the model is ruled out in 13/14 sources because a variable Fe abundance is required. In two sources a spherical distribution is viable, but with nonsolar Fe abundance. We also applied a solar-abundance Compton-thick reflection model, which can account for the spectra that are inconsistent with a spherical model, but spectra with a broader bandpass are required to better constrain model parameters. We also robustly measured the velocity width of the Fe Ka line and found FWHM values of up to approx. 5000 km/s. Only in some spectra was the Fe Ka line unresolved by the HETG.

Coronal Physics and the Chandra Emission Line Project

Science.gov (United States)

Brickhouse, N. S.; Drake, J. J.

2000-01-01

With the launch of the Chandra X-ray Observatory, high resolution X-ray spectroscopy of cosmic sources has begun. Early, deep observations of three stellar coronal sources Capella, Procyon, and HR 1099 are providing not only invaluable calibration data, but also benchmarks for plasma spectral models. These models are needed to interpret data from stellar coronae, galaxies and clusters of galaxies, supernova, remnants and other astrophysical sources. They have been called into question in recent years as problems with understanding low resolution ASCA and moderate resolution Extreme Ultraviolet Explorer Satellite (EUVE) data have arisen. The Emission Line Project is a collaborative effort, to improve the models, with Phase I being the comparison of models with observed spectra of Capella, Procyon, and HR 1099. Goals of these comparisons are (1) to determine and verify accurate and robust diagnostics and (2) to identify and prioritize issues in fundamental spectroscopy which will require further theoretical and/or laboratory work. A critical issue in exploiting the coronal data for these purposes is to understand the extent, to which common simplifying assumptions (coronal equilibrium, negligible optical depth) apply. We will discuss recent, advances in our understanding of stellar coronae, in this context.

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

XAssist: A System for the Automation of X-ray Astrophysics Analysis

Science.gov (United States)

Ptak, A.

2004-08-01

XAssist is a NASA AISR-funded project for the automation of X-ray astrophysics. It is capable of data reprocessing, source detection, and preliminary spatial, temporal and spectral analysis for each source with sufficient counts. The bulk of the system is written in Python, which in turn drives underlying software (CIAO for Chandra data, etc.). Future work will include a GUI (mainly for beginners and status monitoring) and the exposure of at least some functionality as web services. The latter will help XAssist to eventually become part of the VO, making advanced queries possible, such as determining the X-ray fluxes of counterparts to HST or SDSS sources (including the use of unpublished X-ray data), and add the ability of ``on-the-fly'' X-ray processing. Pipelines are running on Chandra and XMM-Newton observations of galaxies to demonstrate XAssist's capabilities, and the results are available online (in real time) at http://www.xassist.org. XAssist itself as well as various associated projects are available for download.

X-RAY AND RADIO EMISSION FROM TYPE IIn SUPERNOVA SN 2010jl

Energy Technology Data Exchange (ETDEWEB)

Chandra, Poonam [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Pune 411 007 (India); Chevalier, Roger A. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Chugai, Nikolai [Institute of Astronomy of Russian Academy of Sciences, Pyatnitskaya St. 48, 109017 Moscow (Russian Federation); Fransson, Claes [Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden); Soderberg, Alicia M., E-mail: poonam@ncra.tifr.res.in [Smithsonian Astrophysical Observatory, 60 Garden St., MS-20, Cambridge, MA 02138 (United States)

2015-09-01

We present all X-ray and radio observations of the Type IIn supernova SN 2010jl. The X-ray observations cover a period up to day 1500 with Chandra, XMM-Newton, NuSTAR, and Swift-X-ray Telescope (XRT). The Chandra observations after 2012 June, the XMM-Newton observation in 2013 November, and most of the Swift-XRT observations until 2014 December are presented for the first time. All the spectra can be fitted by an absorbed hot thermal model except for Chandra spectra on 2011 October and 2012 June when an additional component is needed. Although the origin of this component is uncertain, it is spatially coincident with the supernova and occurs when there are changes to the supernova spectrum in the energy range close to that of the extra component, indicating that the emission is related to the supernova. The X-ray light curve shows an initial plateau followed by a steep drop starting at day ∼300. We attribute the drop to a decrease in the circumstellar density. The column density to the X-ray emission drops rapidly with time, showing that the absorption is in the vicinity of the supernova. We also present Very Large Array radio observations of SN 2010jl. Radio emission was detected from SN 2010jl from day 570 onwards. The radio light curves and spectra suggest that the radio luminosity was close to its maximum at the first detection. The velocity of the shocked ejecta derived assuming synchrotron self-absorption is much less than that estimated from the optical and X-ray observations, suggesting that free–free absorption dominates.

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.

THE CHANDRA HRC VIEW OF THE SUBARCSECOND STRUCTURES IN THE NUCLEAR REGION OF NGC 1068

Energy Technology Data Exchange (ETDEWEB)

Wang Junfeng; Fabbiano, Giuseppina; Karovska, Margarita; Elvis, Martin; Risaliti, Guido, E-mail: juwang@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2012-09-10

We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsec radius region of this galaxy. The HRC image resolves the narrow-line region into X-ray emission clumps matching bright emission-line clouds in the HST [OIII] {lambda}5007 images and allows comparison with subarcsecond-scale radio jet for the first time. Two distinct X-ray knots are revealed at 1.3-1.4 arcsec northeast and southwest of the nucleus. Based on the combined X-ray, [O III], and radio continuum morphology, we identify the locations of intense radio jet-cloud interaction. The [O III] to soft X-ray ratios show that some of these clouds are strongly affected by shock heating, whereas in other locations the jet simply thrusts through with no signs of strong interaction. This is further strengthened by the presence of a kT {approx} 1 keV collisionally ionized component in the ACIS spectrum of a shock-heated cloud HST-G. We estimate that the kinematic luminosity of the jet-driven shocks is 6 Multiplication-Sign 10{sup 38} erg s{sup -1}, a negligible fraction (10{sup -4}) of the estimated total jet power.

THE CHANDRA HRC VIEW OF THE SUBARCSECOND STRUCTURES IN THE NUCLEAR REGION OF NGC 1068

International Nuclear Information System (INIS)

Wang Junfeng; Fabbiano, Giuseppina; Karovska, Margarita; Elvis, Martin; Risaliti, Guido

2012-01-01

We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsec radius region of this galaxy. The HRC image resolves the narrow-line region into X-ray emission clumps matching bright emission-line clouds in the HST [OIII] λ5007 images and allows comparison with subarcsecond-scale radio jet for the first time. Two distinct X-ray knots are revealed at 1.3-1.4 arcsec northeast and southwest of the nucleus. Based on the combined X-ray, [O III], and radio continuum morphology, we identify the locations of intense radio jet-cloud interaction. The [O III] to soft X-ray ratios show that some of these clouds are strongly affected by shock heating, whereas in other locations the jet simply thrusts through with no signs of strong interaction. This is further strengthened by the presence of a kT ∼ 1 keV collisionally ionized component in the ACIS spectrum of a shock-heated cloud HST-G. We estimate that the kinematic luminosity of the jet-driven shocks is 6 × 10 38 erg s –1 , a negligible fraction (10 –4 ) of the estimated total jet power.

X-ray counterpart candidates for six new γ-ray pulsars

Science.gov (United States)

Zyuzin, Dmitry A.; Karpova, Anna V.; Shibanov, Yuriy A.

2018-05-01

Using archival X-ray data, we have found point-like X-ray counterpart candidates positionally coincident with six γ-ray pulsars discovered recently in the Fermi Gamma-ray Space Telescope data by the Einstein@Home project. The candidates for PSRs J0002+6216, J0554+3107, J1844-0346, and J1105-6037 are detected with Swift, and those for PSRs J0359+5414 and J2017+3625 are detected with Chandra. Despite a low count statistics for some candidates, assuming plausible constraints on the absorbing column density towards the pulsars, we show that X-ray spectral properties for all of them are consistent with those observed for other pulsars. J0359+5414 is the most reliably identified object. We detect a nebula around it, whose spectrum and extent suggest that this is a pulsar wind nebula powered by the pulsar. Associations of J0002+6216 and J1844-0346 with supernova remnants CTB 1 and G28.6-0.1 are proposed.

X-ray astronomy

International Nuclear Information System (INIS)

Giacconi, R.; Setti, G.

1980-01-01

This book contains the lectures, and the most important seminars held at the NATO meeting on X-Ray astronomy in Erice, July 1979. The meeting was an opportune forum to discuss the results of the first 8-months of operation of the X-ray satellite, HEAO-2 (Einstein Observatory) which was launched at the end of 1978. Besides surveying these results, the meeting covered extragalactic astronomy, including the relevant observations obtained in other portions of the electromagnetic spectrum (ultra-violet, optical, infrared and radio). The discussion on galactic X-ray sources essentially covered classical binaries, globular clusters and bursters and its significance to extragalactic sources and to high energy astrophysics was borne in mind. (orig.)

X-ray pulsars in nearby irregular galaxies

Science.gov (United States)

Yang, Jun

2018-01-01

The Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC) and Irregular Galaxy IC 10 are valuable laboratories to study the physical, temporal and statistical properties of the X-ray pulsar population with multi-satellite observations, in order to probe fundamental physics. The known distance of these galaxies can help us easily categorize the luminosity of the pulsars and their age difference can be helpful for for studying the origin and evolution of compact objects. Therefore, a complete archive of 116 XMM-Newton PN, 151 Chandra (Advanced CCD Imaging Spectrometer) ACIS, and 952 RXTE PCA observations for the pulsars in the Small Magellanic Cloud (SMC) were collected and analyzed, along with 42 XMM-Newton and 30 Chandra observations for the Large Magellanic Cloud, spanning 1997-2014. From a sample of 67 SMC pulsars we generate a suite of products for each pulsar detection: spin period, flux, event list, high time-resolution light-curve, pulse-profile, periodogram, and X-ray spectrum. Combining all three satellites, I generated complete histories of the spin periods, pulse amplitudes, pulsed fractions and X-ray luminosities. Many of the pulsars show variations in pulse period due to the combination of orbital motion and accretion torques. Long-term spin-up/down trends are seen in 28/25 pulsars respectively, pointing to sustained transfer of mass and angular momentum to the neutron star on decadal timescales. The distributions of pulse detection and flux as functions of spin period provide interesting findings: mapping boundaries of accretion-driven X-ray luminosity, and showing that fast pulsars (P<10 s) are rarely detected, which yet are more prone to giant outbursts. In parallel we compare the observed pulse profiles to our general relativity (GR) model of X-ray emission in order to constrain the physical parameters of the pulsars.In addition, we conduct a search for optical counterparts to X-ray sources in the local dwarf galaxy IC 10 to form a comparison

Characterizing Intermediate-Mass, Pre-Main-Sequence Stars via X-Ray Emision

Science.gov (United States)

Haze Nunez, Evan; Povich, Matthew Samuel; Binder, Breanna Arlene; Broos, Patrick; Townsley, Leisa K.

2018-01-01

The X-ray emission from intermediate-mass, pre-main-sequence stars (IMPS) can provide useful constraints on the ages of very young (${getting power from the gravitational contraction of the star. Main-sequence late-B and A-type stars are not expected to be strong X-ray emitters, because they lack the both strong winds of more massive stars and the magneto-coronal activity of lower-mass stars. There is, however, mounting evidence that IMPS are powerful intrinsic x-ray emitters during their convection-dominated early evolution, before the development and rapid growth of a radiation zone. We present our prime candidates for intrinsic, coronal X-ray emission from IMPS identified in the Chandra Carina Complex Project. The Carina massive star-forming complex is of special interest due to the wide variation of star formation stages within the region. Candidate IMPS were identified using infrared spectral energy distribution (SED) models. X-ray properties, including thermal plasma temperatures and absorption-corrected fluxes, were derived from XSPEC fits performed using absorption ($N_{H}$) constrained by the extinction values returned by the infrared SED fits. We find that IMPS have systematically higher X-ray luminosities compared to their lower-mass cousins, the TTauri stars.This work is supported by the National Science Foundation under grant CAREER-1454334 and by NASA through Chandra Award 18200040.

An X-ray and infrared survey of the Lynds 1228 cloud core

Energy Technology Data Exchange (ETDEWEB)

Skinner, Stephen L. [CASA, University of Colorado, Boulder, CO 80309-0389 (United States); Rebull, Luisa [Spitzer Science Center/Caltech, M/S 220-6, 1200 East California Blvd., Pasadena, CA 91125 (United States); Güdel, Manuel, E-mail: stephen.skinner@colorado.edu, E-mail: rebull@ipac.caltech.edu, E-mail: manuel.guedel@univie.ac.at [Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria)

2014-04-01

The nearby Lynds 1228 (L1228) dark cloud at a distance of ∼200 pc is known to harbor several young stars including the driving sources of the giant HH 199 and HH 200 Herbig-Haro (HH) outflows. L1228 has previously been studied at optical, infrared, and radio wavelengths but not in X-rays. We present results of a sensitive 37 ks Chandra ACIS-I X-ray observation of the L1228 core region. Chandra detected 60 X-ray sources, most of which are faint (<40 counts) and non-variable. Infrared counterparts were identified for 53 of the 60 X-ray sources using archival data from the Two Micron All-Sky Survey, the Spitzer Space Telescope, and the Wide-field Infrared Survey Explorer. Object classes were assigned using mid-IR colors for those objects with complete photometry, most of which were found to have colors consistent with extragalactic background sources. Seven young stellar object candidates were identified including the class I protostar HH 200-IRS which was detected as a faint hard X-ray source. No X-ray emission was detected from the luminous protostar HH 199-IRS. We summarize the X-ray and infrared properties of the detected sources and provide IR spectral energy distribution modeling of high-interest objects including the protostars driving the HH outflows.

On the Binary Nature of Massive Blue Hypergiants: High-resolution X-Ray Spectroscopy Suggests That Cyg OB2 12 is a Colliding Wind Binary

Energy Technology Data Exchange (ETDEWEB)

Oskinova, L. M.; Hamann, W.-R.; Shenar, T.; Sander, A. A. C.; Todt, H.; Hainich, R. [Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam (Germany); Huenemoerder, D. P. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States); Ignace, R., E-mail: lida@astro.physik.uni-potsdam.de [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37663 (United States)

2017-08-10

The blue hypergiant Cyg OB2 12 (B3Ia{sup +}) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xiv and Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well-fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2 12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-ray sources. We suggest that our new Chandra observations of Cyg OB2 12 can be best explained if Cyg OB2 12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2 12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companions.

STATISTICAL CHARACTERIZATION OF THE CHANDRA SOURCE CATALOG

International Nuclear Information System (INIS)

Primini, Francis A.; Evans, Ian N.; Glotfelty, Kenny J.; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G.; Grier, John D.; Hain, Roger M.; Harbo, Peter N.; He Xiangqun; Karovska, Margarita; Houck, John C.; Davis, John E.; Nowak, Michael A.; Hall, Diane M.

2011-01-01

The first release of the Chandra Source Catalog (CSC) contains ∼95,000 X-ray sources in a total area of 0.75% of the entire sky, using data from ∼3900 separate ACIS observations of a multitude of different types of X-ray sources. In order to maximize the scientific benefit of such a large, heterogeneous data set, careful characterization of the statistical properties of the catalog, i.e., completeness, sensitivity, false source rate, and accuracy of source properties, is required. Characterization efforts of other large Chandra catalogs, such as the ChaMP Point Source Catalog or the 2 Mega-second Deep Field Surveys, while informative, cannot serve this purpose, since the CSC analysis procedures are significantly different and the range of allowable data is much less restrictive. We describe here the characterization process for the CSC. This process includes both a comparison of real CSC results with those of other, deeper Chandra catalogs of the same targets and extensive simulations of blank-sky and point-source populations.

X-ray Modeling of Classical Novae

Science.gov (United States)

Nemeth, Peter

2010-01-01

It has been observed and theoretically supported in the last decade that the peak of the spectral energy distribution of classical novae gradually shifts to higher energies at constant bolometric luminosity after a nova event. For this reason, comprehensive evolutionary studies require spectral analysis in multiple spectral bands. After a nova explosion, the white dwarf can maintain stable surface hydrogen burning, the duration of which strongly correlates with the white dwarf mass. During this stage the peak of the luminosity is in the soft X-ray band (15 - 60 Angstroms). By extending the modeling range of TLUSTY/SYNSPEC, I analyse the luminosity and abundance evolution of classical novae. Model atoms required for this work were built using atomic data from NIST/ASD and TOPBASE. The accurate but incomplete set of energy levels and radiative transitions in NIST were completed with calculated data from TOPBASE. Synthetic spectra were then compared to observed data to derive stellar parameters. I show the capabilities and validity of this project on the example of V4743 Sgr. This nova was observed with both Chandra and XMM-Newton observatories and has already been modeled by several scientific groups (PHOENIX, TMAP).

New Insights Into The X-ray Properties Of NGC 1672

Science.gov (United States)

Jenkins, Leigh; Roberts, T.; Brandt, N.; Colbert, E.; Levan, A.; Zezas, A.; Ward, M.

2006-09-01

We present the first results of new Chandra and XMM-Newton X-ray observations of the barred spiral galaxy NGC1672. Previously classified as a Seyfert galaxy, the new combined X-ray imaging and spectral information provides evidence that the nucleus of the galaxy may be almost entirely starburst in nature, presumably triggered and sustained by gas and dust driven to the central region along the galactic bar.

An X-ray perspective on a gamma-ray mission

DEFF Research Database (Denmark)

Lund, Niels

2003-01-01

The most recent astrophysics mission of ESA is INTEGRAL, a mission dedicated to gamma-ray astronomy (Winkler et al. 2003). INTEGRAL carries two gamma-ray instruments: the imager, IBIS, and the spectrometer, SPI, and in addition an optical monitor, OMC, and an X-ray monitor, JEM-X. INTEGRAL is an ...... is an observatory mission with 70% of the observation time available to the general astronomical community through a peer-reviewed selection process. This paper describes the INTEGRAL mission primarily as seen from the JEM-X perspective....

Characterizing the X-ray Emission in Small Magellanic Cloud Supernova Remnants

Science.gov (United States)

Man, Nicole; Auchettl, Katie; Lopez, Laura

2018-01-01

The Small Magellanic Cloud is a close, metal-poor galaxy with active star formation, and it has a diverse population of 24 supernova remnants (SNRs) that have been identified at several wavelengths. Past work has characterized the X-ray emission in these sources separately and aimed to constrain their explosive origins from observations with Chandra and XMM-Newton. Three SNRs have possible evidence for Type Ia explosions based on strong Fe-L emission in their X-ray spectra, although the environments and intermediate-mass element abundances are more consistent with those of core-collapse SNe. In this poster, we analyze the archival Chandra and XMM-Newton observations of the SMC SNR sample, and we model the sources' X-ray spectra in a systematic way to derive the plasma properties and to constrain the nature of the explosions. In one SNR, we note the presence of an X-ray binary near the source's geometric center, suggesting the compact object was produced in the SN explosion. As one of only three SNRs known in the Local Group to host a binary system, this source is worthy of follow-up investigations to probe explosions of massive stars in binary systems.

A Search for Optical Counterparts of Chandra Sources in Omega Centauri using ACS

Science.gov (United States)

Haggard, D.; Fuller, A. D.; Dorfman, J. L.; Cool, A. M.; Anderson, J.; Edmonds, P. D.; Davies, M. B.

2002-12-01

The globular cluster Omega Centauri, with its high mass and large, moderate density core, is of interest both for its population of primordial binaries and for the large number of tidal-capture and/or exchange-collision binaries it may harbor. We have obtained a 3x3 mosaic of Wide Field Camera pointings with HST's Advanced Camera for Surveys, covering a 10'x10' field out to the cluster's half-mass radius. Containing ~1.7 million detected stars, the resulting mosaic represents the most complete image of Omega Cen yet obtained. Here we report preliminary findings of a search in these data for optical counterparts to more than 100 faint X-ray sources (Lx ~ 2 x 1030 - 5 x 1032 erg-s-1) detected in our prior study of Omega Cen using the Chandra X-ray Observatory. Cluster X-ray sources are likely to consist primarily of accreting binary stars and close detached binaries with active coronae. Significant numbers of active galaxies in the background are also expected to be present. Using B, R, and H-alpha images, we are searching for optical counterparts that are H-alpha-bright and blue, as signatures of accretion in cataclysmic variables and/or quiescent low-mass X-ray binaries. Active binaries (e.g., BY Draconis stars) may appear as weaker H-alpha emitters lying on or slightly redward of the main sequence. This work is supported by NASA grant GO-9442 from the Space Telescope Science Institute.

THE REFINED SHOCK VELOCITY OF THE X-RAY FILAMENTS IN THE RCW 86 NORTHEAST RIM

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, Hiroya; Castro, Daniel; Williams, Brian J.; Petre, Robert [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Katsuda, Satoru [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Lopez, Laura A. [Department of Astronomy and Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States); Slane, Patrick O.; Smith, Randall K., E-mail: hiroya.yamaguchi@nasa.gov [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-03-20

A precise measurement of shock velocities is crucial for constraining the mechanism and efficiency of cosmic-ray (CR) acceleration at supernova remnant (SNR) shock fronts. The northeastern rim of the SNR RCW 86 is thought to be a particularly efficient CR acceleration site, owing to the recent result in which an extremely high shock velocity of ∼6000 km s{sup −1} was claimed. Here, we revisit the same SNR rim with the Chandra X-ray Observatory, 11 years after the first observation. This longer baseline than previously available allows us to determine a more accurate proper motion of the nonthermal X-ray filament, revealing a much lower velocity of 3000 ± 340 km s{sup −1} (and even slower at a brighter region). Although the value has dropped to one-half of that from the previous X-ray measurement, it is still higher than the mean velocity of the Hα filaments in this region (∼1200 km s{sup −1}). This discrepancy implies that the filaments bright in nonthermal X-rays and Hα emission trace different velocity components, and thus a CR pressure constrained by combining the X-ray kinematics and the Hα spectroscopy can easily be overestimated. We also measure the proper motion of the thermal X-ray filament immediately to the south of the nonthermal one. The inferred velocity (720 ± 360 km s{sup −1}) is significantly lower than that of the nonthermal filament, suggesting the presence of denser ambient material, possibly a wall formed by a wind from the progenitor, which has drastically slowed down the shock.

Planetary X-ray studies: past, present and future

Science.gov (United States)

Branduardi-Raymont, Graziella

2016-07-01

Our solar system is a fascinating physics laboratory and X-ray observations are now firmly established as a powerful diagnostic tool of the multiple processes taking place in it. The science that X-rays reveal encompasses solar, space plasma and planetary physics, and the response of bodies in the solar system to the impact of the Sun's activity. This talk will review what we know from past observations and what we expect to learn in the short, medium and long term. Observations with Chandra and XMM-Newton have demonstrated that the origin of Jupiter's bright soft X-ray aurorae lies in the Charge eXchange (CX) process, likely to involve the interaction with atmospheric neutrals of local magnetospheric ions, as well as those carried in the solar wind. At higher energies electron bremsstrahlung is thought to be the X-ray emitting mechanism, while the whole planetary disk acts as a mirror for the solar X-ray flux via Thomson and fluorescent scattering. This 'X-ray mirror' phenomenon is all that is observed from Saturn's disk, which otherwise lacks X-ray auroral features. The Earth's X-ray aurora is bright and variable and mostly due to electron bremsstrahlung and line emission from atmospheric species. Un-magnetised planets, Venus and Mars, do not show X-ray aurorae but display the interesting combination of mirroring the solar X-ray flux and producing X-rays by Solar Wind Charge eXchange (SWCX) in their exospheres. These processes respond to different solar stimulation (photons and solar wind plasma respectively) hence their relative contributions are seen to vary according to the Sun's output. Present and future of planetary X-ray studies are very bright. We are preparing for the arrival of the Juno mission at Jupiter this summer and for coordinated observations with Chandra and XMM-Newton on the approach and later during Juno's orbital phase. These will allow direct correlation of the local plasma conditions with the X-ray emissions and the establishment of the

X-RAY EMISSION FROM THE DOUBLE-BINARY OB-STAR SYSTEM QZ CAR (HD 93206)

International Nuclear Information System (INIS)

Parkin, E. R.; Naze, Y.; Rauw, G.; Broos, P. S.; Townsley, L. K.; Pittard, J. M.; Moffat, A. F. J.; Oskinova, L. M.; Waldron, W. L.

2011-01-01

X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P A = 21 days) and B (O8 III+o9 v, P B = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT ≅ 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of ≅0.2 x 10 22 cm -2 . Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of ≅7 x 10 -13 erg s -1 cm -2 , do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III + o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B.

Interstellar Abundances Toward X Per, Revisited

Science.gov (United States)

Valencic, Lynne A.; Smith, Randall K.

2014-01-01

The nearby X-ray binary X Per (HD 24534) provides a useful beacon with which to measure elemental abundances in the local ISM. We examine absorption features of 0, Mg, and Si along this line of sight using spectra from the Chandra Observatory's LETG/ ACIS-S and XMM-Newton's RGS instruments. In general, we find that the abundances and their ratios are similar to those of young F and G stars and the most recent solar values. We compare our results with abundances required by dust grain models.

A DEEP CHANDRA ACIS STUDY OF NGC 4151. I. THE X-RAY MORPHOLOGY OF THE 3 kpc DIAMETER CIRCUM-NUCLEAR REGION AND RELATION TO THE COLD INTERSTELLAR MEDIUM

International Nuclear Information System (INIS)

Wang Junfeng; Fabbiano, Giuseppina; Risaliti, Guido; Elvis, Martin; Karovska, Margarita; Zezas, Andreas; Mundell, Carole G.; Dumas, Gaelle; Schinnerer, Eva

2011-01-01

We report on the imaging analysis of ∼200 ks sub-arcsecond resolution Chandra Advanced CCD Imaging Spectrometer (ACIS-S) observations of the nearby Seyfert 1 galaxy NGC 4151. Bright, structured soft X-ray emission is observed to extend from 30 pc to 1.3 kpc in the southwest from the nucleus, much farther than seen in earlier X-ray studies. The terminus of the northeastern X-ray emission is spatially coincident with a CO gas lane, where the outflow likely encounters dense gas in the host galactic disk. X-ray emission is also detected outside the boundaries of the ionization cone, which indicates that the gas there is not completely shielded from the nuclear continuum, as would be the case for a molecular torus collimating the bicone. In the central r 2 emission and dusty spirals we find in an Hubble Space Telescope V - H color image. The agreement between the observed H 2 line flux and the value predicted from X-ray-irradiated molecular cloud models supports photo-excitation by X-rays from the active nucleus as the origin of the H 2 line, although contribution from UV fluorescence or collisional excitation cannot be ruled out with current data. The discrepancy between the mass of cold molecular gas inferred from recent CO and near-infrared H 2 observations may be explained by the anomalous CO abundance in this X-ray-dominated region. The total H 2 mass derived from the X-ray observation agrees with the recent measurement by Storchi-Bergmann et al.

THE NATURE OF THE BRIGHT ULX X-2 IN NGC 3921: A CHANDRA POSITION AND HST CANDIDATE COUNTERPART

Energy Technology Data Exchange (ETDEWEB)

Jonker, P. G.; Heida, M.; Torres, M. A. P.; Ratti, E. M. [SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Miller-Jones, J. C. A. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Fabian, A. C.; Walton, D. J. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Miniutti, G. [Centro de Astrobiologia (CSIC-INTA), Departamento de Astrofisica, ESA, P.O. Box 78, E-28691 Villanueva de la Canada, Madrid (Spain); Roberts, T. P., E-mail: p.jonker@sron.nl [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

2012-10-10

We report on Chandra observations of the bright ultraluminous X-ray (ULX) source in NGC 3921. Previous XMM-Newton observations reported in the literature show the presence of a bright ULX at a 0.5-10 keV luminosity of 2 Multiplication-Sign 10{sup 40} erg s{sup -1}. Our Chandra observation finds the source at a lower luminosity of Almost-Equal-To 8 Multiplication-Sign 10{sup 39} erg s{sup -1}; furthermore, we provide a Chandra position of the ULX accurate to 0.''7 at 90% confidence. The X-ray variability makes it unlikely that the high luminosity is caused by several separate X-ray sources. In three epochs of archival Hubble Space Telescope observations, we find a candidate counterpart to the ULX. There is direct evidence for variability between the two epochs of WFPC2 F814W observations with the observation obtained in 2000 showing a brighter source. Furthermore, converting the 1994 F336W and 2000 F300W WFPC2 and the 2010 F336W WFC3 observations to the Johnson U-band filter assuming a spectral type of O7I, we find evidence for a brightening of the U-band light in 2000. Using the higher resolution WFC3 observations, we resolve the candidate counterpart into two sources of similar color. We discuss the nature of the ULX and the probable association with the optical counterpart(s). Finally, we investigate a potential new explanation for some (bright) ULXs as the decaying stages of flares caused by the tidal disruption of a star by a recoiled supermassive black hole. However, we find that there should be at most only one of such systems within z = 0.08.

RADIO-QUIET AND RADIO-LOUD PULSARS: SIMILAR IN GAMMA-RAYS BUT DIFFERENT IN X-RAYS

Energy Technology Data Exchange (ETDEWEB)

Marelli, M.; Mignani, R. P.; Luca, A. De; Salvetti, D. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133, Milano (Italy); Parkinson, P. M. Saz [Santa Cruz Institute for Particle Physics, Department of Physics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Hartog, P. R. Den [Stanford University HEPL/KIPAC, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Wolff, M. T., E-mail: marelli@iasf-milano.inaf.it [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

2015-04-01

We present new Chandra and XMM-Newton observations of a sample of eight radio-quiet (RQ) γ-ray pulsars detected by the Fermi Large Area Telescope. For all eight pulsars we identify the X-ray counterpart, based on the X-ray source localization and the best position obtained from γ-ray pulsar timing. For PSR J2030+4415 we found evidence for a ∼10″-long pulsar wind nebula. Our new results consolidate the work from Marelli et al. and confirm that, on average, the γ-ray-to-X-ray flux ratios (F{sub γ}/F{sub X}) of RQ pulsars are higher than for the radio-loud (RL) ones. Furthermore, while the F{sub γ}/F{sub X} distribution features a single peak for the RQ pulsars, the distribution is more dispersed for the RL ones, possibly showing two peaks. We discuss possible implications of these different distributions based on current models for pulsar X-ray emission.

A soft X-ray image of the Moon

International Nuclear Information System (INIS)

Schmitt, J.H.M.M.; Aschenbach, B.; Hasinger, G.; Pfeffermann, E.; Predehl, P.; Truemper, J.; Snowden, S.L.; Wisconsin Univ., Madison, WI

1991-01-01

A soft X-ray image of the Moon obtained by the Roentgen Observatory Satellite ROSAT clearly shows a sunlit crescent, demonstrating that the Moon's X-ray luminosity arises from backscattering of solar X-rays. The Moon's optically dark side is also X-ray dark, and casts a distinct shadow on the diffuse cosmic X-ray background. Unexpectedly, the dark side seems to emit X-rays at a level about one per cent that of the bright side; this emission very probably results from energetic solar-wind electrons striking the Moon's surface. (author)

THE CHANDRA COSMOS LEGACY SURVEY: OPTICAL/IR IDENTIFICATIONS

International Nuclear Information System (INIS)

Marchesi, S.; Civano, F.; Urry, C. M.; Elvis, M.; Salvato, M.; Brusa, M.; Lanzuisi, G.; Vignali, C.; Comastri, A.; Gilli, R.; Zamorani, G.; Cappelluti, N.; Hasinger, G.; Miyaji, T.; Treister, E.; Allevato, V.; Finoguenov, A.; Cardamone, C.; Griffiths, R. E.; Karim, A.

2016-01-01

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 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

An extended X-ray low state from Hercules X-1

International Nuclear Information System (INIS)

Parmar, A.N.; White, N.E.; Barr, P.; Pietsch, W.; Truemper, J.; Voges, W.; McKechnie, S.

1985-01-01

Hercules X-1 exhibits a 35-day cycle in its X-ray intensity in addition to its pulsar rotational and orbital periodicities of 1.24s and 1.7 days respectively. The authors report here observations made with the EXOSAT Observatory between 1983 June and August that failed to detect the expected 35-day variation in X-ray intensity, although low-level extended X-ray emission was seen. The EXOSAT observations suggest that a temporary change in the disk structure may have occurred such that the disk was in the line of sight throughout. (author)

The Origin of the Extra-nuclear X-ray Emission in the Seyfert Galaxy NGC 2992

Science.gov (United States)

Colbert, E. J. M.; Strickland, D. K.; Veilleux, S.; Weaver, K. A.

2004-12-01

We present an analysis of a Chandra ACIS observation of the edge-on Seyfert galaxy NGC 2992. We find extended X-ray emission with Lx(total) in excess of 10**40 erg/s. The brightest nebula is positioned a few 100 pc from the X-ray core, and is spatially coincident with optical line and radio emission. This emission nebula may be energized by the AGN, as opposed to a nuclear starburst. The expected kpc-scale X-ray emission due to a starburst-driven wind is larger than a few 10**39 erg/s, and we present large-scale X-ray emission that may be associated with such an outflow. The extra-nuclear emission has a very soft spectrum. Chandra and XMM spectra of the total nuclear region show a very prominent ``soft excess'' below 2-3 keV. We shall discuss the spectral properties of this soft excess, and will compare with the results from the spatial analysis, and with AGN and starburst models for extranuclear X-ray nebulae.

X-ray Transients in M31

Science.gov (United States)

Kong, A. K. H.; Garcia, M. R.; Primini, F. A.; Murray, S. S.; McClintock, J. E.

2002-06-01

A bright X-ray transient was detected by Chandra on 2002 June 2 with a series of 5 HRC-I snapshots. The new source CXOU J004154.6+405648 (R.A.=00h41m54s.64, Dec.=+40d56m48s.0, +/- 1", J2000) is discovered at a luminosity (0.3-10 keV) of 1.5 x 1038 erg/s (assuming an absorbed power-law model with photon index = 2 and NH = 1021 cm-2 at a distance of 780 kpc).

Chandra Observations of Extended X-Ray Emission in ARP 220

Science.gov (United States)

McDowell, J. C.; Clements, D. L.; Lamb, S. A.; Shaked, S.; Hearn, N. C.; Colina, L.; Mundell, C.; Borne, K.; Baker, A. C.; Arribas, S.

2003-01-01

We resolve the extended X-ray emission from the prototypical ultraluminous infrared galaxy Arp 220. Extended, faint, edge-brightened, soft X-ray lobes outside the optical galaxy are observed to a distance of 1CL 15 kpc on each side of the nuclear region. Bright plumes inside the optical isophotes coincide with the optical line emission and extend 1 1 kpc from end to end across the nucleus. The data for the plumes cannot be fitted by a single-temperature plasma and display a range of temperatures from 0.2 to 1 keV. The plumes emerge from bright, diffuse circumnuclear emission in the inner 3 kpc centered on the Ha peak, which is displaced from the radio nuclei. There is a close morphological correspondence between the Ha and soft X-ray emission on all spatial scales. We interpret the plumes as a starburst-driven superwind and discuss two interpretations of the emission from the lobes in the context of simulations of the merger dynamics of Arp 220.

NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion

Science.gov (United States)

2005-10-01

Intricate wisps of glowing gas float amid a myriad of stars in this image created by combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory. The gas is a supernova remnant, cataloged as N132D, ejected from the explosion of a massive star that occurred some 3,000 years ago. This titanic explosion took place in the Large Magellanic Cloud, a nearby neighbor galaxy of our own Milky Way. The complex structure of N132D is due to the expanding supersonic shock wave from the explosion impacting the interstellar gas of the LMC. Deep within the remnant, the Hubble visible light image reveals a crescent-shaped cloud of pink emission from hydrogen gas, and soft purple wisps that correspond to regions of glowing oxygen emission. A dense background of colorful stars in the LMC is also shown in the Hubble image. The large horseshoe-shaped gas cloud on the left-hand side of the remnant is glowing in X-rays, as imaged by Chandra. In order to emit X-rays, the gas must have been heated to a temperature of about 18 million degrees Fahrenheit (10 million degrees Celsius). A supernova-generated shock wave traveling at a velocity of more than four million miles per hour (2,000 kilometers per second) is continuing to propagate through the low-density medium today. The shock front where the material from the supernova collides with ambient interstellar material in the LMC is responsible for these high temperatures. Chandra image of N132D Chandra image of N132D, 2002 It is estimated that the star that exploded as a supernova to produce the N132D remnant was 10 to 15 times more massive than our own Sun. As fast-moving ejecta from the explosion slam into the cool, dense interstellar clouds in the LMC, complex shock fronts are created. A supernova remnant like N132D provides a rare opportunity for direct observation of stellar material, because it is made of gas that was recently hidden deep inside a star. Thus it provides information on stellar evolution and the

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

Toward Adaptive X-Ray Telescopes

Science.gov (United States)

O'Dell, Stephen L.; Atkins, Carolyn; Button, Tim W.; Cotroneo, Vincenzo; Davis, William N.; Doel, Peer; Feldman, Charlotte H.; Freeman, Mark D.; Gubarev, Mikhail V.; Kolodziejczak, Jeffrey J.;

Weak Hard X-Ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-Ray Weakness

DEFF Research Database (Denmark)

Luo, B.; Brandt, W. N.; Alexander, D. M.

2014-01-01

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z 330 times weaker than...... expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL...... quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three...

Chandra Source Catalog: User Interface

Science.gov (United States)

Bonaventura, Nina; Evans, Ian N.; Rots, Arnold H.; Tibbetts, Michael S.; van Stone, David W.; Zografou, Panagoula; Primini, Francis A.; Glotfelty, Kenny J.; Anderson, Craig S.; Chen, Judy C.; Davis, John E.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G., II; Grier, John D.; Hain, Roger; Hall, Diane M.; Harbo, Peter N.; He, Helen; Houck, John C.; Karovska, Margarita; Kashyap, Vinay L.; Lauer, Jennifer; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph B.; Mitschang, Arik W.; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Nowak, Michael A.; Plummer, David A.; Refsdal, Brian L.; Siemiginowska, Aneta L.; Sundheim, Beth A.; Winkelman, Sherry L.

2009-09-01

The Chandra Source Catalog (CSC) is intended to be the definitive catalog of all X-ray sources detected by Chandra. For each source, the CSC provides positions and multi-band fluxes, as well as derived spatial, spectral, and temporal source properties. Full-field and source region data products are also available, including images, photon event lists, light curves, and spectra. The Chandra X-ray Center CSC website (http://cxc.harvard.edu/csc/) is the place to visit for high-level descriptions of each source property and data product included in the catalog, along with other useful information, such as step-by-step catalog tutorials, answers to FAQs, and a thorough summary of the catalog statistical characterization. Eight categories of detailed catalog documents may be accessed from the navigation bar on most of the 50+ CSC pages; these categories are: About the Catalog, Creating the Catalog, Using the Catalog, Catalog Columns, Column Descriptions, Documents, Conferences, and Useful Links. There are also prominent links to CSCview, the CSC data access GUI, and related help documentation, as well as a tutorial for using the new CSC/Google Earth interface. Catalog source properties are presented in seven scientific categories, within two table views: the Master Source and Source Observations tables. Each X-ray source has one ``master source'' entry and one or more ``source observation'' entries, the details of which are documented on the CSC ``Catalog Columns'' pages. The master source properties represent the best estimates of the properties of a source; these are extensively described on the following pages of the website: Position and Position Errors, Source Flags, Source Extent and Errors, Source Fluxes, Source Significance, Spectral Properties, and Source Variability. The eight tutorials (``threads'') available on the website serve as a collective guide for accessing, understanding, and manipulating the source properties and data products provided by the catalog.

X-Ray Observations of Magnetar SGR 0501+4516 from Outburst to Quiescence

Science.gov (United States)

Mong, Y.-L.; Ng, C.-Y.

2018-01-01

Magnetars are neutron stars having extreme magnetic field strengths. Study of their emission properties in quiescent state can help understand effects of a strong magnetic field on neutron stars. SGR 0501+4516 is a magnetar that was discovered in 2008 during an outburst, which has recently returned to quiescence. We report its spectral and timing properties measured with new and archival observations from the Chandra X-ray Observatory, XMM-Newton, and Suzaku. We found that the quiescent spectrum is best fit by a power-law plus two blackbody model, with temperatures of kT low ∼ 0.26 keV and kT high ∼ 0.62 keV. We interpret these two blackbody components as emission from a hotspot and the entire surface. The hotspot radius shrunk from 1.4 km to 0.49 km since the outburst, and there was a significant correlation between its area and the X-ray luminosity, which agrees well with the prediction by the twisted magnetosphere model. We applied the two-temperature spectral model to all magnetars in quiescence and found that it could be a common feature among the population. Moreover, the temperature of the cooler blackbody shows a general trend with the magnetar field strength, which supports the simple scenario of heating by magnetic field decay.

A SEARCH FOR X-RAY EMISSION FROM COLLIDING MAGNETOSPHERES IN YOUNG ECCENTRIC STELLAR BINARIES

Energy Technology Data Exchange (ETDEWEB)

Getman, Konstantin V.; Broos, Patrick S. [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Kóspál, Ágnes [Konkoly Observatory, Research Center for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Salter, Demerese M. [Department of Astronomy and Laboratory for Millimeter-Wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Garmire, Gordon P. [Huntingdon Institute for X-ray Astronomy, LLC, 10677 Franks Road, Huntingdon, PA 16652 (United States)

2016-12-01

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged sample of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ∼2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.

The kinematics and chemical stratification of the type Ia supernova remnant 0519-69.0 : an XMM-Newton and Chandra study

NARCIS (Netherlands)

Kosenko, D.; Helder, E.A.; Vink, J.

2010-01-01

We present a detailed analysis of the XMM-Newton and Chandra X-ray data of the young type Ia supernova remnant SNR 0519-69.0, which is situated in the Large Magellanic Cloud. We used data from both the Chandra ACIS and XMM-Newton EPIC MOS instruments, and high resolution X-ray spectra obtained with

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.

Benchmarking transition energies and emission strengths for X-ray astrophysics with measurements at the Livermore EBITs

Energy Technology Data Exchange (ETDEWEB)

Hell, Natalie [Friedrich Alexander Univ., Erlangen (Germany)

2017-03-15

K-shell transitions in astrophysically abundant metals and L-shell transitions in Fe group elements show characteristic signatures in the soft X-ray spectrum in the energy range 0.1–10 keV. These signatures have great diagnostic value for plasma parameters such as electron and ion temperatures and densities, and can thus help understand the physics controlling the energetic processes in astrophysical sources. This diagnostic power increases with advances in spectral resolution and effective area of the employed X-ray observatories. However, to make optimal use of the diagnostic potential – whether through global spectral modeling or through diagnostics from local modeling of individual lines – the underlying atomic physics has to be complete and well known. With the next generation of soft X-ray observatories featuring micro-calorimeters such as the SXS on Astro- H/Hitomi and the X-IFU on Athena, broadband high-resolution spectroscopy with large effective area will become more commonly available in the next decade. With these spectrometers, the accuracy of the plasma parameters derived from spectral modeling will be limited by the uncertainty of the reference atomic data rather than by instrumental factors, as is sometimes already the case for the high-resolution grating observations with Chandra-HETG and XMM-Newton-RGS. To take full advantage of the measured spectra, assessment of the accuracy of and improvements to the available atomic reference data are therefore important. Dedicated measurements in the laboratory are essential to benchmark the theoretical calculations providing the bulk of the reference data used in astrophysics. Experiments at the Lawrence Livermore National Laboratory electron beam ion traps (EBIT-I and SuperEBIT) have a long history of providing this service. In this work, I present new measurements of transition energies and absolute electron impact excitation cross sections geared towards currently open atomic physics data needs.

News on the X-ray emission from hot subdwarf stars

Directory of Open Access Journals (Sweden)

Palombara Nicola La

2017-12-01

Full Text Available In latest years, the high sensitivity of the instruments on-board the XMM-Newton and Chandra satellites allowed us to explore the properties of the X-ray emission from hot subdwarf stars. The small but growing sample of X-ray detected hot subdwarfs includes binary systems, in which the X-ray emission is due to wind accretion onto a compact companion (white dwarf or neutron star, as well as isolated sdO stars, in which X-rays are probably due to shock instabilities in the wind. X-ray observations of these low-mass stars provide information which can be useful for our understanding of the weak winds of this type of stars and can lead to the discovery of particularly interesting binary systems. Here we report the most recent results we have recently obtained in this research area.

ESA's X-ray space observatory XMM takes first pictures

Science.gov (United States)

2000-02-01

functioning of the observatory. The Optical Monitor also simultaneously viewed the same regions. One RGS spectrometer obtained its first spectra on 25 January; the other will be commissioned at the start of February. This initial series of short and long duration exposures have delighted the Project management team and the scientists even more. First analyses confirm that the spacecraft is extremely stable, the XMM telescopes are focusing perfectly, and the EPIC cameras, Optical Monitor and RGS spectrometers are working exactly as expected. The Science Operations Centre infrastructure, processing and archiving the science data telemetry from the spacecraft, is also performing well. Initial inspection of the first commissioning images immediately showed some unique X-ray views of several celestial objects, to be presented on 9 February. The occasion will give Principal Investigators and Project management the opportunity to comment on the pictures and the excellent start of the XMM mission. The Calibration and Performance Verification phase for XMM's science instruments is to begin on 3 March, with routine science operations starting in June. Press is invited to attend to the press conference that will be held at the Villafranca/ Madrid- Vilspa facility (ESA's Satellite Tracking Station) Apartado 50727, E-2 080 MADRID, Spain. The press event will be broadcast to the other ESA establishments: ESA Headquarters, Paris; ESA/ ESTEC (Space Expo), Noordwijk, the Netherlands; ESA/ESOC, Darmstadt, Germany and ESA/ESRIN, Frascati, Italy. Media representatives wishing to attend the event are kindly requested to fill out the attached reply from and fax it back to the establishment of their choice.

DISCOVERY OF X-RAY EMISSION FROM AND DISTANCE TO THE SUPERNOVA REMNANT G84.2-0.8

Energy Technology Data Exchange (ETDEWEB)

Leahy, Denis A.; Green, Kaylie S., E-mail: leahy@ucalgary.ca, E-mail: ksgreen@ucalgary.ca [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, T2N 1N4 (Canada)

2012-11-20

We analyze X-ray and radio observations of the supernova remnant G84.2-0.8. 1420 MHz atomic hydrogen (H I) line and radio continuum data yield H I absorption spectra and a new H I absorption distance of 5.8-6.2 kpc. Archival X-ray observations from ROSAT and Chandra which cover the area including G84.2-0.8 are analyzed to show extended X-ray emission from G84.2-0.8. Fits to X-ray spectra from Chandra, with the new H I distance of 5.8-6.2 kpc, are used to determine the Sedov parameters of the supernova remnant. G84.2-0.8 is large (16-18 pc radius), middle aged ({approx}9000 yr), expanding in low-density interstellar medium (0.02 cm{sup -3}), and consistent with a low explosion energy (0.8-6.5 Multiplication-Sign 10{sup 50} erg).

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.;

X-rays from stars

Science.gov (United States)

Güdel, Manuel

2004-07-01

Spectroscopic studies available from Chandra and XMM-Newton play a pivotal part in the understanding of the physical processes in stellar (magnetic and non-magnetic) atmospheres. It is now routinely possible to derive densities and to study the influence of ultraviolet radiation fields, both of which can be used to infer the geometry of the radiating sources. Line profiles provide important information on bulk mass motions and attenuation by neutral matter, e.g. in stellar winds. The increased sensitivity has revealed new types of X-ray sources in systems that were thought to be unlikely places for X-rays: flaring brown dwarfs, including rather old, non-accreting objects, and terminal shocks in jets of young stars are important examples. New clues concerning the role of stellar high-energy processes in the modification of the stellar environment (ionization, spallation, etc.) contribute significantly to our understanding of the "astro-ecology" in forming planetary systems. Technological limitations are evident. The spectral resolution has not reached the level where bulk mass motions in cool stars become easily measurable. Higher resolution would also be important to perform X-ray "Doppler imaging" in order to reconstruct the 3-D distribution of the X-ray sources around a rotating star. Higher sensitivity will be required to perform high-resolution spectroscopy of weak sources such as brown dwarfs or embedded pre-main-sequence sources. A new generation of satellites such as Constellation-X or XEUS should pursue these goals.

The LOFT perspective on neutron star thermonuclear bursts: White paper in support of the mission concept of the large observatory for X-ray timing

Energy Technology Data Exchange (ETDEWEB)

in' t Zand, J. J.M. [SRON Netherlands Institute for Space Research, Utrecht (The Netherlands); Malone, Christopher M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Altamirano, D. [Univ. of Southampton, Southampton (United Kingdom); Ballantyne, D. R. [Georgia Inst. of Technology, Atlanta, GA (United States); Bhattacharyya, S. [Tata Institute of Fundamental Research, Mumbai (India); Brown, E. F. [Michigan State Univ., East Lansing, MI (United States); Cavecchi, Y. [Univ. of Amsterdam, Amsterdam (The Netherlands); Chakrabarty, D. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Chenevez, J. [Technical Univ. of Denmark, Lyngby (Denmark); Cumming, A. [McGill Univ., Montreal, QC (Canada); Degenaar, N. [Univ. of Cambridge, Cambridge (United Kingdom); Falanga, M. [International Space Science Institute, Bern (Switzerland); Galloway, D. K. [Monash Univ., VIC (Australia); Heger, A. [Monash Univ., VIC (Australia); Jose, J. [Univ. Politecnica de Catalunya, Barcelona (Spain); Institut d' Estudis Espacials de Catalunya, Barcelona (Spain); Keek, L. [Georgia Institute of Technology, Atlanta, GA (United States); Linares, M. [Univ. de La Laguna, Tenerife (Spain); Mahmoodifar, S. [Univ. of Maryland, College Park, MD (United States); Mendez, M. [Univ. of Groningen, Groningen (The Netherlands); Miller, M. C. [Univ. of Maryland, College Park, MD (United States); Paerels, F. B. S. [Columbia Astrophysics Lab., New York, NY (United States); Poutanen, J. [Univ. of Turku, Piikkio (Finland); Rozanska, A. [N. Copernicus Astronomical Center PAS, Warsaw (Poland); Schatz, H. [National Superconducting Cyclotron Laboratory at Michigan State University; Serino, M. [Institute of Physical and Chemical Research (RIKEN); Strohmayer, T. E. [NASA' s Goddard Space Flight Center, Greenbelt, MD (United States); Suleimanov, V. F. [Univ. Tubingen, Tubingen (Germany); Thielemann, F. -K. [Univ. Basel, Basel (Switzerland); Watts, A. L. [Univ. of Amsterdam, Amsterdam (The Netherlands); Weinberg, N. N. [Massachusetts Institute of Technology, Cambridge, MA (United States); Woosley, S. E. [Univ. of California, Santa Cruz, CA (United States); Yu, W. [Chinese Academy of Sciences (CAS), Shanghai (China); Zhang, S. [Institute of High-Energy Physics, Beijing (China); Zingale, M. [Stony Brook Univ., Stony Brook, NY (United States)

2015-01-14

The Large Area Detector (LAD) on the Large Observatory For X-ray Timing ( LOFT ), with a 8.5 m 2 photon- collecting area in the 2–30 keV bandpass at CCD-class spectral resolving power (λ/Δλ = 10 – 100), is designed for optimum performance on bright X-ray sources. Thus, it is well-suited to study thermonuclear X-ray bursts from Galactic neutron stars. These bursts will typically yield 2 x 10⁵ photon detections per second in the LAD, which is at least 15 times more than with any other instrument past, current or anticipated. The Wide Field Monitor (WFM) foreseen for LOFT uniquely combines 2–50 keV imaging with large (30%) prompt sky coverage. This will enable the detection of tens of thousands of thermonuclear X-ray bursts during a 3-yr mission, including tens of superbursts. Both numbers are similar or more than the current database gathered in 50 years of X-ray astronomy.

A HIGH FIDELITY SAMPLE OF COLD FRONT CLUSTERS FROM THE CHANDRA ARCHIVE

International Nuclear Information System (INIS)

Owers, Matt S.; Nulsen, Paul E. J.; Markevitch, Maxim; Couch, Warrick J.

2009-01-01

This paper presents a sample of 'cold front' clusters selected from the Chandra archive. The clusters are selected based purely on the existence of surface brightness edges in their Chandra images which are modeled as density jumps. A combination of the derived density and temperature jumps across the fronts is used to select nine robust examples of cold front clusters: 1ES0657 - 558, Abell 1201, Abell 1758N, MS1455.0+2232, Abell 2069, Abell 2142, Abell 2163, RXJ1720.1+2638, and Abell 3667. This sample is the subject of an ongoing study aimed at relating cold fronts to cluster merger activity, and understanding how the merging environment affects the cluster constituents. Here, temperature maps are presented along with the Chandra X-ray images. A dichotomy is found in the sample in that there exists a subsample of cold front clusters which are clearly mergers based on their X-ray morphologies, and a second subsample of clusters which harbor cold fronts, but have surprisingly relaxed X-ray morphologies, and minimal evidence for merger activity at other wavelengths. For this second subsample, the existence of a cold front provides the sole evidence for merger activity at X-ray wavelengths. We discuss how cold fronts can provide additional information which may be used to constrain merger histories, and also the possibility of using cold fronts to distinguish major and minor mergers.

Complex Structure of Galaxy Cluster Abell 1689: Evidence for a Merger from X-Ray Data?

Energy Technology Data Exchange (ETDEWEB)

Andersson, K

2004-01-29

Abell 1689 is a galaxy cluster at z = 0:183 where previous measurements of its mass using various techniques gave discrepant results. We present a new detailed measurement of the mass with the data based on X-ray observations with the European Photon Imaging Camera aboard the XMM-Newton Observatory, determined by using an unparameterized deprojection technique. Fitting the total mass profile to a Navarro-Frenk-White model yields halo concentration c = 7.2{sub -2.4}{sup +1.6} and r{sub 200} = 1.13 {+-} 0.21 h{sup -1} Mpc, corresponding to a mass which is less than half of what is found from gravitational lensing. Adding to the evidence of substructure from optical observations, X-ray analysis shows a highly asymmetric temperature profile and a non-uniform redshift distribution implying large scale relative motion of the gas. A lower than expected gas mass fraction f{sub gas} = 0.072 {+-} 0.008 (for a flat {Lambda}CDM cosmology) suggests a complex spatial and/or dynamical structure. We also find no signs of any additional absorbing component previously reported on the basis of the Chandra data, confirming the XMM low energy response using data from ROSAT.

IDENTIFYING THE LOCATION IN THE HOST GALAXY OF THE SHORT GRB 111117A WITH THE CHANDRA SUBARCSECOND POSITION

Energy Technology Data Exchange (ETDEWEB)

Sakamoto, T.; Troja, E. [Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Aoki, K. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Guiriec, S.; Barthelmy, S. D. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Im, M.; Jeon, Y. [Center for the Exploration of the Origin of the Universe (CEOU), Department of Physics and Astronomy, Seoul National University, Seoul, 151-747 (Korea, Republic of); Leloudas, G.; Malesani, D.; De Ugarte Postigo, A.; Andersen, M. I. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Melandri, A.; D' Avanzo, P. [INAF-Osservatorio Astronomico di Brera, via Bianchi 46, I-23807 Merate (Italy); Urata, Y. [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Xu, D. [Department of Particle Physics and Astronomy, The Weizmann Institute of Science, Rehovot 76100 (Israel); Gorosabel, J.; Sanchez-Ramirez, R. [Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Bai, J. [Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming, Yunnan Province, 650011 (China); Briggs, M. S. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Foley, S. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); and others

2013-03-20

We present our successful Chandra program designed to identify, with subarcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, though no optical afterglow was found in deep optical observations. The host galaxy was clearly detected in the optical and near-infrared band, with the best photometric redshift of z=1.31{sub -0.23}{sup +0.46} (90% confidence), making it one of the highest known short gamma-ray burst (GRB) redshifts. Furthermore, we see an offset of 1.0 {+-} 0.2 arcsec, which corresponds to 8.4 {+-} 1.7 kpc, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining subarcsecond X-ray localizations of short GRB afterglows to study GRB environments.

Weak hard X-ray emission from broad absorption line quasars: evidence for intrinsic X-ray weakness

International Nuclear Information System (INIS)

Luo, B.; Brandt, W. N.; Scott, A. E.; Alexander, D. M.; Gandhi, P.; Stern, D.; Teng, S. H.; Arévalo, P.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Ogle, P.; Puccetti, S.; Saez, C.

2014-01-01

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z < 1.3. However, their rest-frame ≈2 keV luminosities are 14 to >330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index (Γ eff ≈ 1.8) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with <10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (≳ 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

A High Definition View of AGN Feedback: Chandra Imaging of Nearby Seyfert Galaxies

Science.gov (United States)

Wang, Junfeng; Fabbiano, G.; Risaliti, G.; Elvis, M.; Karovska, M.; Zezas, A.; Mundell, C. G.

2010-03-01

To improve the physics of AGN feedback, it is crucial to evaluate the true role of outflows on galaxy evolution observationally. I will present new results from Chandra spectral imaging of nearby Seyfert galaxies, which offer unique opportunities to examine feedback in action in much greater detail than at high redshift. Exploiting Chandra's highest possible resolution, we are able to study structures in NGC 4151 on spatial scales of 0.5 arcsec (30 pc), showing an extended X-ray morphology overall consistent with the optical NLR. We find that most of the NLR clouds in NGC 4151 have [OIII] to soft X-ray ratio consistent with the values observed in NLRs of some Seyfert 2 galaxies, which indicates a uniform ionization parameter even at large radii. We examine various X-ray emission mechanisms of the radio jet and consider thermal emission from interaction between radio outflow and the NLR clouds the most probable origin for the X-ray emission associated with the jet.

On the origin of highly ionized X-ray absorbers detected in the galactic X-ray binaries

International Nuclear Information System (INIS)

Luo, Yang; Fang, Taotao

2014-01-01

X-ray observations of the Galactic X-ray binaries (XRBs) revealed numerous highly ionized metal absorption lines. However, it is unclear whether such lines are produced by the hot interstellar medium (ISM) or the circumstellar medium intrinsic to the binaries. Here we present a Chandra X-ray absorption line study of 28 observations of 12 XRBs, with a focus on the Ne IX and Fe XVII lines. We report the first detections of these lines in a significant amount of observations. We do not find a significant dependence of the line equivalent width on the distance of the XRBs, but we do see a weak dependence on the source X-ray luminosity. We also find 2 out of 12 selected targets show strong temporal variation of the Ne IX absorbers. While the line ratio between the two ion species suggests a temperature consistent with the previous predictions of the ISM, comparing with two theoretical models of the ISM shows the observed column densities are significantly higher than predictions. On the other hand, photoionization by the XRBs provides a reasonably good fit to the data. Our findings suggest that a significant fraction of these X-ray absorbers may originate in the hot gas intrinsic to the XRBs, and that the ISM makes small, if not negligible, contribution. We briefly discuss the implications to the study of the Milky Way hot gas content.

A Multiwavelength Exploration of the Grand Design Spiral M83: Diffuse X-ray Emission

Science.gov (United States)

Kuntz, K. D.; Long, K. S.; Blair, W. P.; Plucinsky, P. P.; Soria, R.; Winkler, P. F.

2013-01-01

We have obtained a series of deep X-ray images of the nearby galaxy M83, with a total exposure 729 ksec with the Chandra ACIS-S array. Since the bulk of the X-ray emitting disk falls within the BI chip, these observations allow a detailed study of the soft diffuse emission in the disk. Most of the diffuse emission is related to star-formation regions and must be powered by supernovae and stellar winds, though the amount of emission due to identifiable SNR is only a few percent. The relation between the spectral shape and surface brightness that was seen in M101 suggests that the properties of the X-ray emission in spiral disks are shaped by the local hot gas production rate (traced by the local star-formation rate) or the disk mid-plane pressure, but it is unclear which physical mechanism dominates. To illuminate this problem, we will compare M83 with the previous Chandra studies of M101 and M33.

Lifting the veil on the X-ray universe

Science.gov (United States)

1999-11-01

detected during rocket-borne experiments. Satellites have since conducted more extensive surveys. The first satellite dedicated to X-ray astronomy was Uhuru. Launched in 1970 it mapped the sky identifying 339 sources. Several others were to follow, including Einstein which carried grazing incidence mirrors and detectors capable of recording images of cosmic X-ray sources. Einstein studied more than ten thousand sources. EXOSAT (1983-1986) was the European Space Agency's first X-ray observatory mission. Placed on a highly eccentric orbit reaching out 191 700 km from Earth, it allowed very long observations above the radiation belts and greatly enlarged our understanding of many classes of X-ray sources. The German/US/UK ROSAT launched in 1990 was another big step forwards. Until its recent switch off it carried out a complete sky survey identifying 100 000 X-ray sources. XMM will be opening up a golden age of X-ray astronomy alongside two other major missions. Launched in July 1999, Chandra is the third of NASA's Great Observatories. It is exploring X-rays from space with images 25 times sharper than previously obtained. ASTRO-E is Japan's fifth X-ray astronomy mission and is due to be launched early in 2000. Europe has already begun studying a next generation X-ray astrophysics facility, XEUS. By making use of the International Space Station and by ensuring significant potential for growth and evolution, XEUS will offer vastly expanded capabilities allowing the study of the very first black holes created when the Universe was just a few percent of its present age.

Small Pixel Hybrid CMOS X-ray Detectors

Science.gov (United States)

Hull, Samuel; Bray, Evan; Burrows, David N.; Chattopadhyay, Tanmoy; Falcone, Abraham; Kern, Matthew; McQuaide, Maria; Wages, Mitchell

2018-01-01

Concepts for future space-based X-ray observatories call for a large effective area and high angular resolution instrument to enable precision X-ray astronomy at high redshift and low luminosity. Hybrid CMOS detectors are well suited for such high throughput instruments, and the Penn State X-ray detector lab, in collaboration with Teledyne Imaging Sensors, has recently developed new small pixel hybrid CMOS X-ray detectors. These prototype 128x128 pixel devices have 12.5 micron pixel pitch, 200 micron fully depleted depth, and include crosstalk eliminating CTIA amplifiers and in-pixel correlated double sampling (CDS) capability. We report on characteristics of these new detectors, including the best read noise ever measured for an X-ray hybrid CMOS detector, 5.67 e- (RMS).

Deep Chandra Observations of ESO 428-G014. II. Spectral Properties and Morphology of the Large-scale Extended X-Ray Emission

Science.gov (United States)

Fabbiano, G.; Paggi, A.; Karovska, M.; Elvis, M.; Maksym, W. P.; Risaliti, G.; Wang, Junfeng

2018-03-01

We present a deep Chandra spectral and spatial study of the kpc-scale diffuse X-ray emission of the Compton-thick (CT) active galactic nucleus (AGN) ESO 428-G014. The entire spectrum is best fit with composite photoionization + thermal models. The diffuse emission is more extended at lower energies (<3 keV). The smaller extent of the hard continuum and Fe Kα profiles implies that the optically thicker clouds responsible for this scattering may be relatively more prevalent closer to the nucleus. These clouds must not prevent soft ionizing X-rays from the AGN escaping to larger radii, in order to have photoionized ISM at larger radii. This suggests that at smaller radii, there may be a larger population of molecular clouds to scatter the hard X-rays, as in the Milky Way. The diffuse emission is also significantly extended in the cross-cone direction, where the AGN emission would be mostly obscured by the torus in the standard AGN model. Our results suggest that the transmission of the obscuring region in the cross-cone direction is ∼10% of that in the cone direction. In the 0.3–1.5 keV band, the ratio of cross-cone to cone photons increases to ∼84%, suggesting an additional soft diffuse emission component disjoint from the AGN. This could be due to hot ISM trapped in the potential of the galaxy. The luminosity of this component, ∼5 × 1038 erg s‑1, is roughly consistent with the thermal component suggested by the spectral fits in the 170–900 pc annulus.

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.

A multiwavelength study of SXP 1062, the long-period X-ray pulsar associated with a supernova remnant

Science.gov (United States)

González-Galán, A.; Oskinova, L. M.; Popov, S. B.; Haberl, F.; Kühnel, M.; Gallagher, J.; Schurch, M. P. E.; Guerrero, M. A.

2018-04-01

SXP 1062 is a Be X-ray binary (BeXB) located in the Small Magellanic Cloud. It hosts a long-period X-ray pulsar and is likely associated with the supernova remnant MCSNR J0127-7332. In this work we present a multiwavelength view on SXP 1062 in different luminosity regimes. We consider monitoring campaigns in optical (OGLE survey) and X-ray (Swift telescope). During these campaigns a tight coincidence of X-ray and optical outbursts is observed. We interpret this as typical Type I outbursts as often detected in BeXBs at periastron passage of the neutron star (NS). To study different X-ray luminosity regimes in depth, during the source quiescence we observed it with XMM-Newton while Chandra observations followed an X-ray outburst. Nearly simultaneously with Chandra observations in X-rays, in optical the RSS/SALT telescope obtained spectra of SXP 1062. On the basis of our multiwavelength campaign we propose a simple scenario where the disc of the Be star is observed face-on, while the orbit of the NS is inclined with respect to the disc. According to the model of quasi-spherical settling accretion our estimation of the magnetic field of the pulsar in SXP 1062 does not require an extremely strong magnetic field at the present time.

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.

The simulated spectrum of the OGRE X-ray EM-CCD camera system

Science.gov (United States)

Lewis, M.; Soman, M.; Holland, A.; Lumb, D.; Tutt, J.; McEntaffer, R.; Schultz, T.; Holland, K.

2017-12-01

The X-ray astronomical telescopes in use today, such as Chandra and XMM-Newton, use X-ray grating spectrometers to probe the high energy physics of the Universe. These instruments typically use reflective optics for focussing onto gratings that disperse incident X-rays across a detector, often a Charge-Coupled Device (CCD). The X-ray energy is determined from the position that it was detected on the CCD. Improved technology for the next generation of X-ray grating spectrometers has been developed and will be tested on a sounding rocket experiment known as the Off-plane Grating Rocket Experiment (OGRE). OGRE aims to capture the highest resolution soft X-ray spectrum of Capella, a well-known astronomical X-ray source, during an observation period lasting between 3 and 6 minutes whilst proving the performance and suitability of three key components. These three components consist of a telescope made from silicon mirrors, gold coated silicon X-ray diffraction gratings and a camera that comprises of four Electron-Multiplying (EM)-CCDs that will be arranged to observe the soft X-rays dispersed by the gratings. EM-CCDs have an architecture similar to standard CCDs, with the addition of an EM gain register where the electron signal is amplified so that the effective signal-to-noise ratio of the imager is improved. The devices also have incredibly favourable Quantum Efficiency values for detecting soft X-ray photons. On OGRE, this improved detector performance allows for easier identification of low energy X-rays and fast readouts due to the amplified signal charge making readout noise almost negligible. A simulation that applies the OGRE instrument performance to the Capella soft X-ray spectrum has been developed that allows the distribution of X-rays onto the EM-CCDs to be predicted. A proposed optical model is also discussed which would enable the missions minimum success criteria's photon count requirement to have a high chance of being met with the shortest possible

Identification of Hard X-ray Sources in Galactic Globular Clusters: Simbol-X Simulations

Science.gov (United States)

Servillat, M.

2009-05-01

Globular clusters harbour an excess of X-ray sources compared to the number of X-ray sources in the Galactic plane. It has been proposed that many of these X-ray sources are cataclysmic variables that have an intermediate magnetic field, i.e. intermediate polars, which remains to be confirmed and understood. We present here several methods to identify intermediate polars in globular clusters from multiwavelength analysis. First, we report on XMM-Newton, Chandra and HST observations of the very dense Galactic globular cluster NGC 2808. By comparing UV and X-ray properties of the cataclysmic variable candidates, the fraction of intermediate polars in this cluster can be estimated. We also present the optical spectra of two cataclysmic variables in the globular cluster M 22. The HeII (4868 Å) emission line in these spectra could be related to the presence of a magnetic field in these objects. Simulations of Simbol-X observations indicate that the angular resolution is sufficient to study X-ray sources in the core of close, less dense globular clusters, such as M 22. The sensitivity of Simbol-X in an extended energy band up to 80 keV will allow us to discriminate between hard X-ray sources (such as magnetic cataclysmic variables) and soft X-ray sources (such as chromospherically active binaries).

Chandra resolves the T Tauri binary system RW Aur

Energy Technology Data Exchange (ETDEWEB)

Skinner, Stephen L. [CASA, University of Colorado, Boulder, CO 80309-0389 (United States); Güdel, Manuel, E-mail: stephen.skinner@colorado.edu, E-mail: manuel.guedel@univie.ac.at [Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria)

2014-06-20

RW Aur is a multiple T Tauri system consisting of an early-K type primary (A) and a K5 companion (B) at a separation of 1.''4. RW Aur A drives a bipolar optical jet that is well characterized optically. We present results of a sensitive Chandra observation whose primary objective was to search for evidence of soft extended X-ray emission along the jet, as has been seen for a few other nearby T Tauri stars. The binary is clearly resolved by Chandra and both stars are detected as X-ray sources. The X-ray spectra of both stars reveal evidence for cool and hot plasma. Surprisingly, the X-ray luminosity of the less-massive secondary is at least twice that of the primary and is variable. The disparity is attributed to the primary whose X-ray luminosity is at the low end of the range for classical T Tauri stars of similar mass based on established correlations. Deconvolved soft-band images show evidence for slight outward elongation of the source structure of RW Aur A along the blueshifted jet axis inside the central arcsecond. In addition, a faint X-ray emission peak is present on the redshifted axis at an offset of 1.''2 ± 0.''2 from the star. Deprojected jet speeds determined from previous optical studies are too low to explain this faint emission peak as shock-heated jet plasma. Thus, unless flow speeds in the redshifted jet have been underestimated, other mechanisms such as magnetic jet heating may be involved.

SMART-X: Square Meter, Arcsecond Resolution Telescope for X-rays

Science.gov (United States)

Vikhlinin, Alexey; SMART-X Collaboration

2013-04-01

SMART-X is a concept for a next-generation X-ray observatory with large-area, 0.5" angular resolution grazing incidence adjustable X-ray mirrors, high-throughput critical angle transmission gratings, and X-ray microcalorimeter and CMOS-based imager in the focal plane. High angular resolution is enabled by new technology based on controlling the shape of mirror segments using thin film piezo actuators deposited on the back surface. Science applications include observations of growth of supermassive black holes since redshifts of ~10, ultra-deep surveys over 10's of square degrees, galaxy assembly at z=2-3, as well as new opportunities in the high-resolution X-ray spectroscopy and time domains. We also review the progress in technology development, tests, and mission design over the past year.

The X-ray imager on AXO

DEFF Research Database (Denmark)

Budtz-Jørgensen, Carl; Kuvvetli, Irfan; Westergaard, Niels Jørgen Stenfeldt

2001-01-01

DSRI has initiated a development program of CZT X-ray and gamma-ray detectors employing strip readout techniques. A dramatic improvement of the energy response was found operating the detectors as the so-called drift detectors. For the electronic readout, modern ASIC chips were investigated....... Modular design and the low-power electronics will make large area detectors using the drift strip method feasible. The performance of a prototype CZT system will be presented and discussed. One such detector system has been proposed for future space missions: the X-Ray Imager (XRI) on the Atmospheric X-ray...... Observatory (AXO), which is a mission proposed to the Danish Small Satellite Program and is dedicated to observations of X-ray generating processes in the Earth's atmosphere. Of special interest will be simultaneous optical and X-ray observations of sprites that are flashes appearing directly above an active...

Pixel detectors for x-ray imaging spectroscopy in space

International Nuclear Information System (INIS)

Treis, J; Andritschke, R; Hartmann, R; Herrmann, S; Holl, P; Lauf, T; Lechner, P; Lutz, G; Meidinger, N; Porro, M; Richter, R H; Schopper, F; Soltau, H; Strueder, L

2009-01-01

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 x 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

Pixel detectors for x-ray imaging spectroscopy in space

Energy Technology Data Exchange (ETDEWEB)

Treis, J; Andritschke, R; Hartmann, R; Herrmann, S; Holl, P; Lauf, T; Lechner, P; Lutz, G; Meidinger, N; Porro, M; Richter, R H; Schopper, F; Soltau, H; Strueder, L [MPI Semiconductor Laboratory, Otto-Hahn-Ring 6, D-81739 Munich (Germany)], E-mail: jft@hll.mpg.de

2009-03-15

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 x 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

The Chandra Source Catalog: Storage and Interfaces

Science.gov (United States)

van Stone, David; Harbo, Peter N.; Tibbetts, Michael S.; Zografou, Panagoula; Evans, Ian N.; Primini, Francis A.; Glotfelty, Kenny J.; Anderson, Craig S.; Bonaventura, Nina R.; Chen, Judy C.; Davis, John E.; Doe, Stephen M.; Evans, Janet D.; Fabbiano, Giuseppina; Galle, Elizabeth C.; Gibbs, Danny G., II; Grier, John D.; Hain, Roger; Hall, Diane M.; He, Xiang Qun (Helen); Houck, John C.; Karovska, Margarita; Kashyap, Vinay L.; Lauer, Jennifer; McCollough, Michael L.; McDowell, Jonathan C.; Miller, Joseph B.; Mitschang, Arik W.; Morgan, Douglas L.; Mossman, Amy E.; Nichols, Joy S.; Nowak, Michael A.; Plummer, David A.; Refsdal, Brian L.; Rots, Arnold H.; Siemiginowska, Aneta L.; Sundheim, Beth A.; Winkelman, Sherry L.

2009-09-01

The Chandra Source Catalog (CSC) is part of the Chandra Data Archive (CDA) at the Chandra X-ray Center. The catalog contains source properties and associated data objects such as images, spectra, and lightcurves. The source properties are stored in relational databases and the data objects are stored in files with their metadata stored in databases. The CDA supports different versions of the catalog: multiple fixed release versions and a live database version. There are several interfaces to the catalog: CSCview, a graphical interface for building and submitting queries and for retrieving data objects; a command-line interface for property and source searches using ADQL; and VO-compliant services discoverable though the VO registry. This poster describes the structure of the catalog and provides an overview of the interfaces.

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.

Observations of EUV and X-ray Emission from Comets

Science.gov (United States)

Lisse, C.

The unexpected discovery of x-ray emission from Comet Hyakutake in March 1996 (Lisse et al. 1996) produced a number of questions about the physical mechanism producing the radiation. The original detection and subsequent observations have shown that the very soft (best fit thermal bremsstrahlung model kT0.2 keV) emission is due to an interaction between the solar wind and the comet's atmosphere. Using the results from the more than 15 comets detected to date in x-rays, I report here on the latest results on cometary x-ray emission, including new results from Chandra, and show that charge exchange between highly ionized minor ions in the solar wind and neutral gases in the cometary coma is the most likely operative mechanism. I then use this result to study a number of problems of astrophysical interest: the nature of the cometary coma, other possible sources of x-ray emission in the solar system, the structure of the solar wind in the heliosphere, and the source of the local x-ray background.

A Spectral Analysis of the X-Ray Pulsar 4U 1907+09 obtained at thePeriastron Passage with the XMM-Newton Observatory

NARCIS (Netherlands)

Balman, Solen; Mendez, Mariano; Diaz Trigo, Maria; Inam, Cagdas; Baykal, Altan

2010-01-01

We present results from a 20 ksec observation of the wind-accreting X-ray pulsar 4U 1907+09 obtained using the XMM-Newton Observatory at the periastron passage. The XMM-Newton spectrum allows us to study the continuum emission and the emission line at 6.4 keV with the high sensitivity and

A hybrid concept (segmented plus monolithic fused silica shells) for a high-throughput and high-angular resolution x-ray mission (Lynx/X-Ray Surveyor like)

Science.gov (United States)

Basso, Stefano; Civitani, Marta; Pareschi, Giovanni; Parodi, Giancarlo

2017-09-01

Lynx is a large area and high angular resolution X-ray mission being studied by NASA to be presented to the next Decadal Survey for the implementation in the next decade. It aims to realize an X-ray telescope with the effective area similar to Athena (2 m2 at 1 keV) but with the same angular resolution of Chandra and a much larger Field Of View (up 20 arcmin x 20 arcmin). The science of X-ray Surveyor requires a large-throughput mirror assembly with sub-arcsec angular resolution. These future X-ray mirrors have a set of requirements which, collectively, represents very substantial advances over any currently in operation or planned for missions other than X-ray Surveyor. Of particular importance is achieving low mass per unit collecting area, while maintaining Chandra like angular resolution. Among the possible solutions under study, the direct polishing of both thin monolithic pseudo-cylindrical shells and segments made of fused silica are being considered as viable solutions for the implementation of the mirrors. Fused silica has very good thermomechanical parameters (including a very low CTE), making the material particularly well suited for for the production of the Lynx mirrors. It should be noted that the use of close shells is also very attractive, since the operations for the integration of the shells will be greatly simplified and the area lost due to the vignetting from the interfacing structures minimized even if the management of such big (diameter of 3 m) and thin shells have to be demonstrated. In this paper we will discuss a possible basic layout for a full shell mirror and a hybrid concept (segmented plus monolithic shells made of fused silica) as a second solution, for the Lynx/XRS telescope, discussing preliminary results in terms of optical and mechanical performance.

Pixel detectors for x-ray imaging spectroscopy in space

Science.gov (United States)

Treis, J.; Andritschke, R.; Hartmann, R.; Herrmann, S.; Holl, P.; Lauf, T.; Lechner, P.; Lutz, G.; Meidinger, N.; Porro, M.; Richter, R. H.; Schopper, F.; Soltau, H.; Strüder, L.

2009-03-01

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 × 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

X-RAY STUDIES OF THE BLACK WIDOW PULSAR PSR B1957+20

International Nuclear Information System (INIS)

Huang, R. H. H.; Kong, A. K. H.; Takata, J.; Cheng, K. S.; Hui, C. Y.; Lin, L. C. C.

2012-01-01

We report on Chandra observations of the black widow pulsar, PSR B1957+20. Evidence for a binary-phase dependence of the X-ray emission from the pulsar is found with a deep observation. The binary-phase-resolved spectral analysis reveals non-thermal X-ray emission of PSR B1957+20, confirming the results of previous studies. This suggests that the X-rays are mostly due to intra-binary shock emission, which is strongest when the pulsar wind interacts with the ablated material from the companion star. The geometry of the peak emission is determined in our study. The marginal softening of the spectrum of the non-thermal X-ray tail may indicate that particles injected at the termination shock are dominated by synchrotron cooling.

X-rays from Wolf-Rayet stars observed by the Einstein observatory

International Nuclear Information System (INIS)

Sanders, W.T.; Cassinelli, J.P.; Hucht, K.A. van der

1982-01-01

Preliminary results of three X-ray surveys are presented. Out of a sample of 20 stars, X-rays were detected from four Wolf-Rayet stars and two O8f + stars. The detected stars have about the same mean value as O stars for the X-ray to total luminosity ratio, Lsub(x)/L = 10 -7 , but exhibit a much larger variation about the mean. The spectral energy distributions are also found to be like that of O stars in that they do not exhibit large attenuation of X-rays softer than 1 keV. This indicates that for both the O stars and WR stars much of the X-ray emission is coming from hot wisps or shocks in the outer regions of the winds and not from a thin source at the base of the wind. The general spectral shape and flux level place severe restrictions on models that attribute the lack of hydrogen emission lines to extremely high temperatures of the gas in the wind. (Auth.)

Some observational aspects of compact galactic X-ray sources

International Nuclear Information System (INIS)