相关论文: Background Radiation
We discuss how the interaction between the electrons in a relativistic jet and the Cosmic Microwave Background (CMB) affects the observable properties of radio-loud AGN at early epochs. At high z the magnetic energy density in the radio…
The information content of the autocorrelation function (ACF) of intensity fluctuations of the X-ray background (XRB) is analyzed. The tight upper limits set by ROSAT deep survey data on the ACF at arcmin scales imply strong constraints on…
Submillimetre observations reveal a cosmologically significant population of high-redshift dust-enshrouded galaxies. The form of evolution inferred for this population can be reconciled easily with COBE FIRAS and DIRBE measurements of the…
A synthesis model for the cosmic X-ray Background (XRB) is presented, which includes a proper treatment of Compton scattering in the absorbing matter for type 2 AGN. Evidence for a decrease of the relative importance of type 2 AGN at high…
The origin of the extragalactic gamma-ray background (EGRB) radiation has been a mystery in astrophysics for a long time. Recently the Fermi gamma-ray satellite (Fermi) has revealed that ~22% of the unresolved EGRB would be explained by…
We aim at clarifying the nature of the emission of two spatially related unidentified X-ray sources detected with XMM-Newton telescope at intermediate-low Galactic latitude. Observations reveal a point-like source aligned with elongated…
Recent X-ray surveys have now resolved most of the X-ray background (XRB) into discrete sources. While this represents a break- through in the understanding of the XRB, the astrophysical nature of these sources still remains mysterious. In…
The ARCADE 2 balloon bolometer along with a number of other instruments have detected what appears to be a radio synchrotron background at frequencies below about 3 GHz. Neither extragalactic radio sources nor diffuse Galactic emission can…
Using ROSAT observations, we estimate gas pressures in the X-ray-emitting medium surrounding 63 FRII radio galaxies and quasars. We compare these pressures with the internal pressures of the radio-emitting plasma estimated by assuming…
Recent measurements of the cosmic X-ray and radio backgrounds (CXB/CRB, respectively) obtained with Chandra and ARCADE2 report signals in excess of those expected from known sources, suggesting the presence of a yet undiscovered population…
Whether X-ray emission in radio-loud (RL) active galactic nuclei (AGNs) originates from disk coronae or jets is still under debate. For example, the positive relationships in radio-quiet (RQ) AGNs (such as the optical to X-ray spectral…
This is the second of a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. In Capetti et al. (2005) we presented a study of the…
We present a two-parameter model of the extragalactic gamma-ray background (EGB) in the 0.1-100 GeV range as measured by the Large Area Telescope (LAT) onboard the Fermi satellite. The EGB can be fully explained as the sum of three distinct…
We present high-resolution radio observations of a sample of 65 radio sources at low Galactic latitudes. The sources were all observed at 5 GHz with the Very Large Array A-array. MERLIN observations at 5 GHz of the ultracompact HII region…
While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton…
We propose a model for the source of the X-ray background (XRB) in which low luminosity active nuclei (L<10^43 erg/s) are obscured by nuclear starbursts within the inner 100pc. The obscuring material covers most of the sky as seen from the…
We discuss the main uncertainties affecting estimates of small scale fluctuations due to extragalactic sources in the Planck Surveyor frequency bands. Conservative estimates allow us to confidently conclude that, in the frequency range…
We review estimates of small scale fluctuations due to extragalactic point sources in the Planck Surveyor frequency bands. While our undestanding of the spectral and evolutionary properties of these sources is far from complete,…
We present a catalog of 290 "winged" or X-shaped radio galaxies (XRGs) extracted from the latest (2014 December 17) data release of the "Very Large Array Faint Images of the Radio Sky at Twenty centimeter." We have combined these radio…
I review the assumptions and observations that motivate the concept of the extragalactic cosmic background radiation, and the issues of energy accounts and star formation history as a function of galaxy morphological type that figure in the…