Related papers: Unifying models for X-ray selected and Radio selec…
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…
BL Lac objects are an elusive and rare class of active galactic nuclei. For years their evolutionary behavior has appeared inconsistent with the trend observed in the population of AGN at large. The so-called ``negative'' evolution implies…
We present a preliminary investigation of the spectral energy distributions (SEDs), and star-formation properties of a sample of Mid-IR selected Quasars. The mid-infrared SEDs of our objects are consistent with that expected from clumpy…
ROSAT observations of a large sample of bright gamma-ray (E > 100 MeV) blazars are presented. Results of a detailed spectral analysis in the soft $\sim$ 0.1-2.0 keV energy range are discussed in relation to the overall energy distribution…
We investigate the physical properties of BL Lac objects (BL Lacs) jets by modeling the quasi-simultaneous spectral energy distributions (SEDs) of 22 {\it Fermi} BL Lac objects in the frame of a simple one-zone synchrotron self-Compton…
We use the distributions of spectral indices of a large homogenous sample of Fermi-detected blazars to re-investigate the relationship between flat spectrum radio quasars (FSRQs) and subclasses of BL Lac objects (BL Lacs). We compute the…
We study the BL Lac objects detected in the one year all sky survey of the Fermi satellite, with a energy spectral slope alpha_gamma in the [0.1-100 GeV] band greater than 1.2. In the alpha_gamma vs gamma-ray luminosity plane, these BL Lacs…
Context. The advent of Fermi is changing our understanding on the radio and gamma-ray emission in Active Galactic Nuclei. Contrary to pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the gamma-ray band. However,…
We present a radio/optical study of a sample of BL Lac objects at arcsecond and milliarcsecond resolution. The sample consists of 30 nearby (z<0.2) BL Lacs, mostly X-ray selected. These nearby objects are weak in the radio, yet we have…
Observations of candidate BL Lacertae objects spectroscopically selected from the Sloan Digital Sky Survey (SDSS) reveal a large fraction with high polarization (P > 3%). This result confirms that synchrotron radiation makes an important…
X-ray surveys contain sizable numbers of star forming galaxies, beyond the AGN which usually make the majority of detections. Many methods to separate the two populations are used in the literature, based on X-ray and multiwavelength…
Gigahertz Peaked Spectrum (GPS) sources and Compact Symmetric Objects (CSO) are selected in very different ways, but have a significant overlap in properties. Ever since their discovery it has been speculated that they are young objects,…
We propose a unified classification for BL Lac objects (BLs), focusing on the synchrotron peak frequency of the spectral energy distribution. The unification scheme is based on the angle Theta that describes the orientation of the…
Combining newly identified and previously known BL Lacs from the RASS-Green Bank (RGB) catalog, we present a sample of 127 BL Lacs, the largest ever derived from a single uniform survey. A Complete sample of 33 objects brighter than O=18.0…
We investigate quantitatively how the peak emission frequency of the overall energy spectrum is at work in distinguishing RBL-like and XBL-like objects. We employ the sample of Giommi et al. (1995) to study the distribution of BL Lacertae…
We selected a sample of 437 BL Lac objects, taken from the RomaBZCat catalogue, for which spectroscopic information and SDSS photometry is available. We propose a new classification of BL Lacs in which the sources' type is not defined only…
We present the results of the BeppoSAX observations of two BL Lacs, OQ 530 and S5 0716+714, as part of a ToO program for the simultaneous observation at radio, optical, X-ray and TeV energies. Both sources are detected in the LECS and MECS,…
Statistical analyses are invaluable methods used to understand intrinsic emission processes and the unification of extragalactic radio sources. In this paper, we collected radio, X-ray and {\gamma}-ray data of blazars from the Fermi-LAT and…
We present the timing analysis of 10 archived \XMM observations with an exposure of $>40$ ks of Markarian 421. Mrk 421 is the brightest high-frequency-peaked BL Lac object (HBL) emitting in X-rays produced by electrons accelerated in the…
We report the results of a new analysis of 13 wide band BeppoSAX observations of the BL Lac object Mkn 421. The data from LECS, MECS and PDS, covering an energy interval from 0.1 to over 100 keV, have been used to study the spectral…