The Complex Broad Band X Ray Spectra Of Seyfert Galaxies PDF Download
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Author | : Kimberly Weaver |
Publisher | : |
Total Pages | : 336 |
Release | : 1993 |
Genre | : Astronomical spectroscopy |
ISBN | : |
Download The Complex Broad-band X-ray Spectra of Seyfert Galaxies Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 456 |
Release | : 1995 |
Genre | : Aeronautics |
ISBN | : |
Download Scientific and Technical Aerospace Reports Book in PDF, ePub and Kindle
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author | : |
Publisher | : |
Total Pages | : 29 |
Release | : 2010 |
Genre | : |
ISBN | : |
Download X-ray Emitting GHz-Peaked Spectrum Galaxies Book in PDF, ePub and Kindle
In a dynamical-radiative model we recently developed to describe the physics of compact, GHz-Peaked-Spectrum (GPS) sources, the relativistic jets propagate across the inner, kpc-sized region of the host galaxy, while the electron population of the expanding lobes evolves and emits synchrotron and inverse-Compton (IC) radiation. Interstellar-medium gas clouds engulfed by the expanding lobes, and photoionized by the active nucleus, are responsible for the radio spectral turnover through free-free absorption (FFA) of the synchrotron photons. The model provides a description of the evolution of the GPS spectral energy distribution (SED) with the source expansion, predicting significant and complex high-energy emission, from the X-ray to the [gamma]-ray frequency domain. Here, we test this model with the broad-band SEDs of a sample of eleven X-ray emitting GPS galaxies with Compact-Symmetric-Object (CSO) morphology, and show that: (i) the shape of the radio continuum at frequencies lower than the spectral turnover is indeed well accounted for by the FFA mechanism; (ii) the observed X-ray spectra can be interpreted as non-thermal radiation produced via IC scattering of the local radiation fields off the lobe particles, providing a viable alternative to the thermal, accretion-disk dominated scenario. We also show that the relation between the hydrogen column densities derived from the X-ray (N{sub H}) and radio (N{sub HI}) data of the sources is suggestive of a positive correlation, which, if confirmed by future observations, would provide further support to our scenario of high-energy emitting lobes.
Author | : Stephen S. Holt |
Publisher | : |
Total Pages | : 36 |
Release | : 1980 |
Genre | : Astronomical spectroscopy |
ISBN | : |
Download Spectroscopy of Compact Extragalactic X-ray Sources Book in PDF, ePub and Kindle
Author | : Peter J. Serlemitsos |
Publisher | : |
Total Pages | : 612 |
Release | : 1993 |
Genre | : Astronomical spectroscopy |
ISBN | : |
Download BBXRT Book in PDF, ePub and Kindle
Author | : George H. Jacoby |
Publisher | : |
Total Pages | : 652 |
Release | : 1996 |
Genre | : Astronomy |
ISBN | : |
Download Astronomical Data Analysis Software and Systems V Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 12 |
Release | : 1995 |
Genre | : |
ISBN | : |
Download The Average X-Ray/Gamma-Ray Spectra of Seyfert Galaxies From Ginga and OSSE and the Origin of the Cosmic X-Ray Background Book in PDF, ePub and Kindle
We have obtained the first average 2-500 keV spectra of Seyfert galaxies, using the data from Ginga and GRO OSSE. Our sample contains 3 classes of objects with markedly different spectra: radio-quiet Seyfert 1s and 2s, and radio-loud Seyfert 1s. The average radio-quiet Seyfert 1 spectrum is well- fitted by a power law continuum with the energy spectral index approximately equal 0.9, a Compton reflection component corresponding to a ~ 2x covering solid angle, and ionized absorption. There is a high-energy cutoff in the incident power law continuum: the e-folding energy is E(sub c) approximately equal 0.6 (sup +0.8, sub -0.3)MeV. The simplest model that describes this spectrum is Comptonization in a relativistic optically-thin thermal corona above the surface of an accretion disk. Radio-quiet Seyfert 2s show strong neutral absorption, and there is an indication that their X-ray power laws are intrinsically harder, although the Seyfert 1 spectrum with = 0.9 and strong reflection cannot be ruled out by the data. Finally, the radio-loud Seyfert spectrum has alpha approximately equal 0.7, moderate neutral absorption, E (sub c) = 0.4(sup +0.7, sub -0.2) MeV, and no or little Compton reflection. This is incompatible with the radio-quiet Seyfert 1 spectrum, and probably indicating that the X-rays are beamed away from the accretion disk in these objects. The average spectra of Seyferts integrated over redshift with a power law evolution can explain the hard X-ray spectrum of the cosmic background. The hump at ~ 30 keV in that spectrum is due to the dominant contribution of Seyfert 2s.
Author | : Franco Giovannelli |
Publisher | : Springer Science & Business Media |
Total Pages | : 456 |
Release | : 2004-08-03 |
Genre | : Science |
ISBN | : 9781402022463 |
Download The Impact of Space Experiments on Our Knowledge of the Physics of the Universe Book in PDF, ePub and Kindle
Space experiments have opened practically all electromagnetic windows on the Universe. A discussion of the most important results obtained with multi-frequency photonic astrophysics experiments will provide new input to advance our knowledge of physics, very often in its more extreme conditions. A multitude of high quality data across the whole electromagnetic spectrum came at the scientific community's disposal a few years after the beginning of the Space Era. With these data we are attempting to explain the physics governing the Universe and its origin, which continues to be a matter of the greatest curiosity for humanity. In this book we describe the latest steps of the investigations born with the advent of space experiments. We highlight the most important results, identify unsolved problems, and comment on perspectives we can reasonably expect. This book aims to provide a useful tool for the reader who is not specialized in space astrophysics and for students. Therefore, the book is written in the form of a review with a still reasonable length, taking into account the complexity of the arguments discussed. We do not claim to present a complete picture of the physics governing the Universe, but have rather selected particular topics for a more thorough discussion. A cross section of essays on historical, modern, and philosophical topics is offered and combined with personal views into tricks of the space astrophysics trade.
Author | : Cosimo Bambi |
Publisher | : Springer Nature |
Total Pages | : 5912 |
Release | : |
Genre | : |
ISBN | : 9811969604 |
Download Handbook of X-ray and Gamma-ray Astrophysics Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 812 |
Release | : 1992 |
Genre | : Physics |
ISBN | : |
Download Physics Briefs Book in PDF, ePub and Kindle