Download or read book XMM Newton Observations of Ultraluminous X ray Sources and Their Host Galaxies written by Ann-Marie Stobbart and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optical X ray Studies of Ultraluminous X ray Sources written by Jeanette Claire Gladstone and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultraluminous X-ray Sources (ULXs) are point like X-ray sources situated external to the nucleus of their host galaxy, with inferred X-ray luminosities in excess of 10 {39} erg s {?1} . Although?rst observed? 30 years ago, these sources are yet to be fully understood. Some have suggested that these fascinating objects may contain intermediate mass black holes, whilst others have proposed they are stellar mass black holes residing in a new extreme accretion state. This thesis works towards the conclusion of this debate, by developing our understanding of these systems and their environments. This work begins with a photometric survey of the optical counterparts of ULXs. The main aim of this survey is to?nd plausible candidates to gain radial velocity measurements and therefore mass functions of these systems. However, the collation of this sample also provides the opportunity to classify the stellar objects held within these systems. From this work, we?nd seven good candidates for optical spectroscopic follow-up. Our results also show that many of our sample are consistent with OB type stars, while some contain later type bright giants/supergiants. Possibly our best chance to gain precise measurements of M_{BH}, and settling the debate over the nature of these systems, is by using radial velocity curves of their optical counterparts to calculate a mass function of ULXs. We are currently undertaking a programme to pursue mass function measurements for these systems. To date, we have received the pilot spectra of three optical counterparts. We discuss the progress of this programme to date and perform analysis on both the absorption/emission features and the continuum of these spectra. Initial analysis reveals the presence of the He ii 4686 A line in two of our pilot spectra. This line may be associated with the accretion disc of these systems, and could therefore be used in our pursuit of the mass function. We also?nd the presence of both low and high ionization lines, with some evidence for shock ionisation, and electron temperature of 7,000? 10,000 K. This Balmer decrement also indicates that the extinction can be highly variable across ULX?eld. This combination may suggest a?patchy? environment with separate shock and photoionisation emission regions. While the continuum emission of one of our sample can be explained by either the spectra of an OB star or of a standard accretion disc, the steep slopes of two of our sample indicates non-stellar origins that could represent the optical spectrum of a super-Eddington accretion disc. Finally, this work highlights the need for further observations of these sources in order to unlock their nature. We present results of X-ray spectral variability studies of the ULX population contained within NGC 4485 & 4490. We collate Chandra and XMM-Newton observations of the interacting galaxy pair, to analyse the emission from the six ULXs previously identified, and one additional source observed in the a recent exposure. This provides us with an opportunity to study variability on both short and longer time scales. The spectral variability is generally characterised by a hardening of the source spectra as their luminosities increase. The sources show a variety of long-term light curves; however, short-term (intra-observational) temporal variability is conspicuous by its absence. This survey also reveals the detection of a possible change in accretion state that could be used to gain crude mass estimates of the compact objects. Finally, we explore further the variability of these systems with the aid of two new proprietary observations. Finally, analysis of some of the best quality X-ray spectral data publicly available on these sources has provided the opportunity to explore the nature of these systems. We apply phenomenological models to characterise the spectra of these objects and more physically motivated models in order to explore the physical processes underlying these characteristics. Results show that the spectra of these sources are fundamentally different to that of Galactic X-ray binaries, whilst the application of physical models indicates a more extreme version of the highest known luminosity state, the very high state. We therefore speculate that in observing ULXs we are observing stellar mass black holes residing in a new?ultraluminous? state.
Download or read book Spectral Analysis of Ultraluminous X ray Sources Using the Chandra Xray Observatory written by Akram Chandrajit Singha, A Senorita Devi and published by Sankalp Publication. This book was released on with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive introduction to the data analysis of ultraluminous X-ray sources. This book will provide the readers with a familiar environment in data analysis methods and the different software used in high energy astrophysical data analysis.
Download or read book Xmm Newton Archival Study of the Ulx Population in Nearby Galaxies written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-08 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have conducted an archival XMM-Newton study of the bright X-ray point sources in 32 nearby galaxies. From our list of approximately 100 point sources, we attempt to determine if there is a low-state counterpart to the Ultraluminous X-ray (ULX) population. Indeed, 16 sources in our sample match the criteria we set for a low-state ULX, namely, L(sub X) greater than 10(exp 38 ergs per second) and a spectrum best fit with an absorbed power law. Further, we find evidence for 26 high-state ULXs which are best fit by a combined blackbody and a power law. As in Galactic black hole systems, the spectral indices, GAMMA, of the low-state objects, as well a s the luminosities, tend to be lower than those of the high-state objects. The observed range of blackbody temperatures is 0.1-1 keV with the most luminous systems tending toward the lowest temperatures. We also find a class of object whose properties (luminosity, blackbody temperature, and power law slopes) are very similar to those of galactic stellar mass black holes. In addition, we find a subset of these objects that can be best fit by a Comptonized spectrum similar to that used for Galactic black holes in the very high state, when they are radiating near the Eddington limit.
Download or read book High Energy Studies of Active Galactic Nuclei with XMM Newton written by Rebecca Jane Smith and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultra luminous X ray Sources written by Jifeng Liu and published by . This book was released on 2005 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Accretion Processes in Astrophysics written by Ignacio Gonzl̀ez Martn̕ez-Pas̕ and published by Cambridge University Press. This book was released on 2014-02-17 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been more than fifty years since the first significant paper on accretion flows was written. In recent years, X-ray satellites capable of identifying accretion disks and radiation jets - indications that accretion has taken place - have significantly advanced our understanding of these phenomena. This volume presents a comprehensive and up-to-date introduction to the major theoretical and observational topics associated with accretion processes in astrophysics. Comprising lectures presented at the twenty-first Winter School of the Canary Islands Institute of Astrophysics, the text emphasises the physical aspects of accretion, investigating how radiation jets are produced, how accretion power is divided between jets and radiated energy, the geometry of accretion flow, and the accretion processes of active galactic nuclei. Written by an international team of experienced scientists, chapters offer young researchers key analytical tools for supporting and carrying out the next generation of front-line research.
Download or read book The Universe in X Rays written by Joachim E. Trümper and published by Springer Science & Business Media. This book was released on 2008-02-05 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions from leading scientists in the field, and edited by two of the most prominent astronomers of our time, this is a totally authoritative volume on X-ray astronomy that will be essential reading for everyone interested – from students to astrophysicists and physicists. All the aspects of this exciting area of study are covered, from astronomical instrumentation to extragalactic X-ray astronomy.
Download or read book X ray Studies of Ultraluminous Infrared Galaxies Observed with XMM Newton written by Ralf Keil and published by . This book was released on 2006 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Restless Universe written by Eric Matthew Schlegel and published by . This book was released on 2002 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Multiwavelength Mapping of Galaxy Formation and Evolution written by Alvio Renzini and published by Springer Science & Business Media. This book was released on 2005-05-23 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: The possibilities of astronomical observation have dramatically increased over the last decade. Major satellites, like the Hubble Space Telescope, Chandra and XMM Newton, are complemented by numerous large ground-based observatories, from 8m-10m optical telescopes to sub-mm and radio facilities. As a result, observational astronomy has access to virtually the whole electromagnetic spectrum of galaxies, even at high redshifts. Theoretical models of galaxy formation and cosmological evolution now face a serious challenge to match the plethora of observational data. In October 2003, over 170 astronomers from 15 countries met for a 4-day workshop to extensively illustrate and discuss all major observational projects and ongoing theoretical efforts to model galaxy formation and evolution. This volume contains the complete proceedings of this meeting and is therefore a unique and timely overview of the current state of research in this rapidly evolving field.
Download or read book Neutron Stars Black Holes and Binary X Ray Sources written by H. Gursky and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a set of articles based on a session of the annual meeting of the American Association for the Advancement of Science held in San Francisco in February, 1974. The reason for the meeting arose from the need to communicate to the largest possible scientific community the dramatic advances which have been made in recent years in the understanding of collapsed objects: neutron stars and black holes. Thanks to an unprecedented resonance between X-ray, y-ray, radio and optical astronomy and important new theoretical developments in relativistic astro physics, a new deep understanding has been acquired of the physical processes oc curring in the late stages of evolution of stars. This knowledge may be one of the greatest conquests of man's understanding of nature in this century. This book aims to give an essential and up-to-date view in this field. The analysis of the physics and astrophysics of neutron stars and black holes is here attacked from both theoretical and experimental points of view. In the experimental field we range from the reviews and catalogues of galactic X-ray sources (R. Gursky and E. Schreier) and pulsars (E. Groth) to the observations of the optical counter part of X-ray sources (P. Boynton) to finally the recently discovered gamma-ray bursts (I. Strong) and pulse astronomy R. B. Partridge).
Download or read book The X ray Background written by Xavier Barcons and published by Cambridge University Press. This book was released on 1992-07-31 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the current observational knowledge and understanding of the cosmic X-ray background.
Download or read book Timing Neutron Stars written by H. Ögelman and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: The idea for organizing an Advanced Study Institute devoted largely to neutron star timing arose independently in three places, at Istanbul, Garching and Amster dam; when we became aware of each other's ideas we decided to join forces. The choice of a place for the Institute, in Turkey, appealed much to us all, and it was then quickly decided that Qe§me would be an excellent spot. When the preparations for the Institute started, early in 1987, we could not have guessed how timely the subject actually was. Of course, the recently dis covered QPO phenomena in accreting neutron stars and half a dozen binary and millisecond radio pulsars known at the time formed one of the basic motivations for organizing this Institute. But none of us could have guessed that later in 1987 we were to witness the wonderful discovery of the binary and millisecond radio pulsars in globular clusters and, -as if Nature wished to give us a special present for this the discovery in March 1988 of a millisecond pulsar in an eclipsing binary Institu- system, the first eclipsing radio pulsar ever found, and the second fastest in the sky! The discussion of this pulsar, its formation and fate was one of the highlights of this meeting, especially since its discoverers were among the participants of the Institute and could provide us with first-hand information.
Download or read book Handbook of X ray and Gamma ray Astrophysics written by Cosimo Bambi and published by Springer Nature. This book was released on with total page 5912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book XMM Newton Observations of the Heavily Absorbed Seyfert 1 Galaxy IC 4329A written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We detect seven distinct absorbing systems in the high-resolution X-ray spectrum of the Seyfert 1 galaxy IC 4329A, taken with XMM-Newton. Firstly we detect absorption due to cold gas in our own Galaxy and warm gas in the Galactic halo or the Local Group. This local warm gas is only detected through O VII absorption, from which we deduce a temperature between 0.03 and 0.2 keV. In IC 4329A we detect absorption from the host galaxy as well as from a warm absorber, close to the nucleus, which has 4 components. The absorption from the host galaxy is well modeled by neutral material. The warm absorber detected in IC 4329A is photoionized and has an ionization range between log [xi] = -1.37 and log [xi] = 2.7. A broad excess is measured at the O VIII Ly[alpha] and N VII Ly[alpha] emission lines, which can be modeled by either disklines or multiple Gaussians. From the lightcurve we find that the source changed luminosity by about 20 % over the 140 ks observation, while the spectral shape, i.e. the softness ratio did not vary. In the EPIC spectra a narrow Fe K[alpha] and Fe XXVI Ly[alpha] emission line are detected. The narrowness of the Fe K[alpha] line and the fact that there is no evidence for flux variability between different observations leads us to conclude that the Fe K[alpha] line is formed at a large distance from the central black hole.
Download or read book XMM Newton Observations of the Galactic Centre Region written by Victoria Heard and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
