Related papers: A tentative elementary model of quasars
A joint hadronic model is shown to quantitatively explain the observations of diffuse radio emission from galaxy clusters in the form of minihalos, giant halos, relics, and their hybrid, transitional stages. Cosmic-ray diffusion of order…
All quasar spectra show the same atomic features in the optical, UV, near-IR and soft X-rays over all of cosmic time, luminosity black hole mass and accretion rate. This is a puzzle. Here I show that it is possible that all of these atomic…
It is currently unknown whether the Universe was reionized by quasars or stars at z>5. We point out that quasars can be best distinguished from stellar systems by their X-ray emission. Based on a simple hierarchical CDM model, we predict…
Our multi-wavelength model GRASIL for the SED of galaxies is described, in particular the recent extension to the radio and X-ray range. With our model we can study different aspects of galaxy evolution by exploiting all available spectral…
D. Reimers and H.-J. Hagen report in A&A 329, L25 (1998) that a QSO of z = .807 is a "by chance projection" on the center of a galaxy of z = .009. A considerable amount of previously published evidence would lead us to expect an active, low…
Near-infrared images of the luminous, high redshift (z=2.1108) radio loud quasar 4C+09.17 reveal a complex structure. The quasar (K=15.76 mag) is surrounded by three "companion" objects having 17.9< K < 20.2 mag at radii of 1.7" < r < 2.9",…
The flat spectrum radio quasars (FSRQs) are a sub-class of blazars characterised by prominent optical emission lines and a collimated large-scale jet along the observer line of sight. An X-ray spectral flattening has been reported in FSRQs…
We present a Chandra and XMM-Newton spectral analysis of the nuclei of the radio galaxies and radio-loud quasars from the 3CRR sample in the redshift range 0.1 < z < 0.5. In the range of radio luminosity sampled by these objects, mostly…
A recent Chandra observation of the nearby galaxy cluster Abell 585 has led to the discovery of an extended X-ray jet associated with the high-redshift background quasar B3 0727+409, a luminous radio source at redshift z=2.5. This is one of…
Using a sample of over 25000 spectroscopically confirmed quasars from the Sloan Digital Sky Survey, we show how quasar variability in the rest frame optical/UV regime depends upon rest frame time lag, luminosity, rest wavelength, redshift,…
The large observed redshift of quasars has suggested large cosmological distances and a corresponding enormous energy output to explain the brightness or luminosity as seen at earth. Alternative or complementary sources of redshift have not…
We show that the complex shape of the cosmic ray (CR) spectrum, as recently measured by PAMELA and inferred from Fermi-LAT gamma-ray observations of molecular clouds in the Gould belt, can be naturally understood in terms of basic plasma…
It is commonly accepted that quasar redshifts have a cosmological character and that most of the quasars are at Gigaparsec distances. However, there are some cases where several quasars with completely different redshifts and a nearby…
We present the results of hard-X-ray observations of four broad-line radio galaxies (BLRGs) with the Rossi X-Ray Timing Explorer (RXTE). The original motivation behind the observations was to search for systematic differences between the…
The excellent soft X-ray sensitivity of the PSPC detector onboard the ROSAT satellite provided the first chance to study precisely the spectral and timing properties of Narrow-Line Seyfert 1 galaxies. ROSAT observations of Narrow-Line…
Updates are provided on several issues related to Unified Models. A new HST spectrum of Cygnus A confirms the broad MgII emission line, and suggests a very large velocity width as seen in the polarized optical lines. Statistics of the 3CR…
The law introduced by Karlsson in spectroscopy of low-redshift quasars involves the Lyman spectrum of hydrogen atoms. Thus, it appears necessary to study the concepts introduced by a standard spectroscopy of quasars, studied here, with…
Most galaxy evolutionary models require quasar feedback to regulate star formation in their host galaxies. In particular, at high redshift, models expect that feedback associated with quasar-driven outflows is so efficient that the gas in…
In the currently popular orientation-based unified scheme, a radio galaxy appears as a quasar when its principal radio-axis happens to be oriented within a certain cone opening angle around the observer's line of sight. Due to geometrical…
We present results from high-resolution radio and optical observations of PMN J0134-0931, a gravitational lens with a unique radio morphology and an extremely red optical counterpart. Our data support the theory of Keeton & Winn (2003):…