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Radiative Transfer in a Clumpy Universe. IV. New Synthesis Models of the Cosmic UV/X-Ray Background
We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative
Radiative Transfer in a Clumpy Universe. II. The Ultraviolet Extragalactic Background
We present a detailed calculation of the propagation of AGN-like ionizing radiation through the intergalactic space. We model the ionization state of absorbing clouds, and show that the universe will
Radiative Transfer in a Clumpy Universe. III. The Nature of Cosmological Ionizing Sources
The history of the transition from a neutral intergalactic medium (IGM) to one that is almost fully ionized can reveal the character of cosmological ionizing sources. We study the evolution of the
A two-phase model for the X-ray emission from Seyfert galaxies
A two-phase accretion disk model is considered. A substantial fraction, f, of the gravitational power is assumed to be dissipated via buoyancy and reconnection of magnetic fields in a hot tenuous
X-Ray Spectra from Two-Phase Accretion Disks
A model for the X-ray emission from radio-quiet active galactic nuclei (AGNs) is considered. The X-rays are produced via inverse Compton (IC) emission in a hot corona embedding a colder accretion
Simultaneous X-ray and 7-ray observations of Cyg X-1 in the hard state by Ginga and OSSE
We present four X-ray/gamma-ray spectra of Cyg X-1 observed in the hard ('low') state simultaneously by Ginga and GRO/OSSE on 1991 July 6. The 3-30 keV Ginga spectra are well represented by power
The Assembly and Merging History of Supermassive Black Holes in Hierarchical Models of Galaxy Formation
We assess models for the assembly of supermassive black holes (SMBHs) at the center of galaxies that trace their hierarchical buildup far up in the dark halo merger tree. Motivated by the recent
Cosmic Reionization after Planck: Could Quasars Do It All?
We assess a model of late cosmic reionization in which the ionizing background radiation arises entirely from high redshift quasars and other active galactic nuclei (AGNs). The low optical depth to
The Contribution of the obscuring torus to the x-ray spectrum of Seyfert galaxies: A Test for the unification model
The presence of an obscuring torus around the nucleus of a Seyfert galaxy, as supposed in the popular unification scheme, can strongly modify the X-ray spectrum for both type 1 and type 2 Seyfert