Related papers: MeV synchrotron BL Lacs

All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources…

Extreme high-energy peaked BL Lac objects (EHBLs) are an emerging class of blazars with exceptional spectral properties. The non-thermal emission of the relativistic jet peaks in the spectral energy distribution (SED) plot with the…

We propose a scenario where blazars are classified as flat-spectrum radio quasars (FSRQs), BL Lacs, low synchrotron, or high synchrotron peaked objects according to a varying mix of the Doppler boosted radiation from the jet, the emission…

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…

The extreme synchrotron BL Lac object H2356-309, located at a redshift of z = 0.165, was observed from June to December 2004 with a total exposure of approx. 40 h live-time with the H.E.S.S. (High Energy Stereoscopic System) array of…

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…

We present EVN observations of seven BL Lac objects selected from the RGB sample. To investigate the intrinsic radiation property of BL Lac objects, we estimated the Doppler factor with the VLA or MERLIN core and the total 408 MHz…

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and…

Markarian 421 is the nearest high-energy peaked blazar and also is the first extragalactic source to be detected in multi-TeV $\gamma$-rays. It has been observed in multiwavelength for exceptionally long period of time with dense monitoring…

We investigate the spectroscopic optical properties of gamma-ray sources detected with high significance above 50 GeV in the Third Catalog of Hard Fermi-LAT Sources (3FHL) and that are good candidates as TeV emitters. We focus on the 91…

We study the synchrotron component of the spectral energy distribution (SED) on the sample of 877 blazars using the ASDC SED Builder Tool with available broadband data from the literature. Our sample includes 423 flat-spectrum radio sources…

Blazars have been pointed out as promising high-energy (HE) neutrinos sources, although the mechanism is still under debate. The blazars with a hard-TeV spectrum, which leptonic models can hardly explain, can be successfully interpreted in…

We present multiwavelength observations of the BL Lacertae object Markarian 501 (Mrk 501) in 1997 between April 8 and April 19. Evidence of correlated variability is seen in very high energy (VHE, E > 350 GeV) gamma-ray observations taken…

The emission of very-high-energy photons (VHE, E$>$100 GeV) in active galactic nuclei (AGN) is closely connected with the production of ultra-relativistic particles. Among AGN, the subclass of extreme BL Lacertae are of particular interest…

The discovery of high-energy astrophysical neutrinos by IceCube kicked off a new line of research to identify the electromagnetic counterparts producing these neutrinos. Among the extragalactic sources, active galactic nuclei (AGN), and in…

We apply the synchrotron proton blazar (SPB) model to the April 1997 flare of Markarian 501 and find we are able to fit the observed spectral energy distribution. We explore the effect of target photon density on the high energy part of the…

We report on the 1.6 GHz (18 cm) VLBI observations of the unresolved, steady TeV source HESS J1943+213 located in the Galactic plane, performed with the European VLBI Network (EVN) in 2014. Our new observations with a nearly full EVN array…

The BL Lac object 1ES 1011+496 was discovered at Very High Energy gamma-rays by MAGIC in spring 2007. Before that the source was little studied in different wavelengths. Therefore a multi-wavelength (MWL) campaign was organized in spring…

We present the analysis of archival data from ROSAT and ASCA of a serendipitous BL Lac object PKS 2316-423. Because of its featureless non-thermal radio/optical continuum, PKS 2316-423 has been called as a BL Lac candidate in the…

The large majority of BL Lacertae objects belonging to the 1 Jy sample, the class prototype for radio-selected sources, are thought to emit most of their synchrotron power in the far IR band. Ironically, this spectral region is very…