Related papers: X-ray Selected BL Lacs and Blazars
We use statistical results from a large sample of about 500 blazars, based on two surveys, the Deep X-ray Radio Blazar Survey (DXRBS), nearly complete, and the RASS-Green Bank survey (RGB), to provide new constraints on the spectral energy…
Although blazars are thought to emit most of their luminosity in the gamma-ray band, there are subclasses of them very prominent in hard X-rays. These are the best candidates to be studied by Simbol-X. They are at the extremes of the blazar…
The multi-frequency `Sedentary Survey' is a deep, statistically complete, radio flux limited sample comprising 150 BL Lacertae objects distinguished by their extremely high X-ray to radio flux ratio, ranging from five hundred to over five…
With its very wide energy band (0.1-100 keV), BeppoSAX has played a fundamental role in the blazar field, allowing in particular a better study of the highest synchrotron peaked objects. Here we summarize the results of an observational…
Average Spectral Energy Distributions (SED) for different subgroups of blazars are derived from available homogeneous (but small) data sets, including the gamma-ray band. Comparing Flat Spectrum Radio Quasars (FSRQ) with BL Lacs extracted…
We study the quasi-simultaneous near-IR, optical, UV, and X-ray photometry of eleven gamma-ray selected blazars for which redshift estimates larger than 1.2 have been recently provided. Four of these objects turn out to be high-power…
Active galactic nuclei (AGNs) can power relativistic jets, which are called blazars when pointed close to our line of sight. Depending on the presence or absence of emission lines in their optical spectra, blazars are categorized into flat…
Blazars are the brightest and most abundant persistent sources in the extragalactic gamma-ray sky. Due to their significance, they are often observed across various energy bands to explore potential correlations between emissions at…
Recent observations of blazars at high energy (HE, 0.1-100 GeV) and very high energy (VHE, >0.1 TeV) have provided important constraints on the intensity and spectrum of the diffuse Extragalactic Background Light (EBL), shedding light on…
We study the four BL Lac objects (RGB J0152+017, 1ES 0229+200, 1ES 0347-121 and PKS 0548-322) detected in the TeV band but not present in the 1FGL catalogue of the Fermi/Large Area Telescope. We analize the 24 months of LAT data deriving…
The blazar 1ES 0229+200 is a high frequency peaked BL Lac object with a hard TeV spectrum extending to 10 TeV. Its unusual spectral characteristics make it a frequently used probe for intergalactic radiation and magnetic fields. With new,…
BL Lac objects are known to have very energetic jets pointing towards the observer under small viewing angles. Many of these show high luminosity over the whole energy range up to TeV, mostly classified as high-energy peaked BL Lac objects.…
Extreme synchrotron blazars, characterized by a first peak in their broadband spectral energy distributions (SEDs) at frequencies exceeding $10^{17}$ Hz, often exhibit a second peak beyond 1~TeV. These sources serve as ideal laboratories…
TeV emission can be a common characteristic of low power blazars. This is in line with the sequence of blazars relating the observed bolometric luminosity with their overall spectral energy distribution. Detecting new TeV blazars, possibly…
The majority of the extragalactic sources yet detected at TeV photon energies belong to the class of "high frequency peaked BL Lacs" (HBLs) that exhibit a spectral energy distribution with a lower peak in the X-ray band. Such spectra are…
Lately a specific kind of blazars drew the attention of the gamma-ray astronomy community: the extreme TeV BL Lacs, blazars that present an extremely energetic and hard emission at very high-energy. Explaining their features is still an…
The double humped SED (Spectral Energy Distribution) of blazars, and their flaring phenomena can be explained by various leptonic and hadronic models. However, accurate modeling of the high frequency component and clear identification of…
We put forward a scenario where blazars are classified as flat-spectrum radio quasars, BL Lacs, low synchrotron, or high synchrotron peaked objects according to a varying combination of Doppler boosted radiation from the jet, emission from…
The highest-energy blazars exhibit non-thermal radiation extending beyond 1 TeV with high luminosities and strong variabilities, indicating extreme particle acceleration in their relativistic jets. The gamma-ray spectra of blazars contain…
We report on our observations of the parsec-scale radio jet structures of five blazars that have been detected by ground-based TeV gamma-ray telescopes. These five blazars all belong to the class of high-frequency peaked BL Lac objects…