ﻻ يوجد ملخص باللغة العربية
We consider archival ROSAT and HST observations of five FRI radio galaxies and isolate their nuclear emission from that of the host galaxy. This enable us to determine the Spectral Energy Distributions (SED) of their nuclei spanning from the radio to the X-ray band. They cannot be described as single power-laws but require the presence of an emission peak located between the IR and soft X-ray band. We found consistency between the SED peak position and the values of the broad band spectral indices of radio galaxies with those of BL Lac, once the effects of beaming are properly taken into account. FRI SED are thus qualitatively similar to those of BL Lacs supporting the identification of FRI sources as their mis-oriented counterparts. No dependence of the shape of the SED on the FR~I orientation is found.
We examine the optical properties of the nuclei of low luminosity radio-galaxies using snapshot HST images of the B2 sample. In agreement with the results obtained from the analysis of the brighter 3C/FRI sample, we find a correlation between fluxes
We collect multi-wavelength measurements of the nuclear emission of 20 low luminosity FR I radio-galaxies to test the viability of the FR I - BL Lac unifying model. Although poorly sampled, the Spectral Energy Distributions (SED) of FR Is are consist
We present deep, multi-VLA-configuration radio images for a set of 18 quasars, having redshifts between 0.36 and 2.5, from the 7C quasar survey. Approximately one quarter of these quasars have FRI-type twin-jet structures and the remainder are a broa
We collect data from the radio to the gamma-ray range for three complete samples of blazars: the Slew Survey and the 1Jy samples of BL Lacs and the 2Jy sample of Flat Spectrum Radio-Loud Quasars (FSRQs). The fraction of objects detected in gamma-rays
We present nuclear spectral energy distributions (SEDs) in the range 0.4-16micron for an expanded CfA sample of Seyfert galaxies. The spectral indices from 1-16micron range from alpha_IR 0.9 to 3.8. The shapes of the spectra are correlated with Seyfe