Related papers: Synchrotron and Compton Components and their Varia…
We study the X-ray spectra of 85 BL Lacertae objects using the hardness ratios as given in the WGA catalogue of {\it ROSAT} sources. This sample includes all WGA BL Lacs with high-quality data and comprises about 50 per cent of presently…
We analyze how the spectrum of synchrotron and inverse Compton radiation from a narrow relativistic jet changes with the observation angle. It is shown that diversity of acceleration mechanisms (in particular, taking the converter mechanism…
We report the variable X-ray emission from BL Lacertae detected in the ASCA ToO observation conducted during the EGRET and RXTE pointings, coincident with the 1997 July outburst. The source showed a historically high state of X-ray,…
We review the current status of resolved X-ray emission associated with extragalactic radio jets and hotspots. The primary question for any particular jet is to decide if the X-rays come from the synchrotron process or from inverse Compton…
The high frequency component in blazars is thought to be due to inverse Compton scattered radiation. Recent observations by Fermi-LAT are used to evaluate the details of the scattering process. A comparison is made between the usually…
Models that seek to unify BL Lacs and low-power radio galaxies predict that the two types of object should show similar isotropically emitted X-ray emission. Testing this is usually limited by difficulties in separating strong X-ray…
We present recent ROSAT, ASCA and SAX observations of intermediate BL Lac objects (IBLs), i.e. BL Lacs which are located between high-energy and low-energy peaked BL Lac objects with respect to alpha_rx. Both the statistical properties of…
When gamma-rays emerge from a central source they may undergo Compton scattering in surrounding matter. The resulting Compton-scattered electrons radiate. Coherent radiation by such Compton electrons follows nuclear explosions above the…
A techniques, describing electron dynamics for magnetic models closed to cyclical accelerators, is developed and applied to the analysis of electromagnetic radiation emitted by charged particles. Formulas for the angular characteristics of…
This paper reports the first discovery of possible inverse Compoton (IC) X-ray emission below 10 keV in the typical high-energy peaked BL Lac object (HBL) PKS 2155--304. Two XMM-Newton observations performed in 2006 reveal that the 0.6--10…
Some rapidly variable extra-galactic radio sources show very high brightness temperatures T_B>10^{12}K and high degrees of circular polarisation (1%). Standard synchrotron models that assume a power-law electron distribution cannot produce…
Observations at millimetre wavelengths are presented for a representative sample of 22 X-ray-selected BL Lac objects (XBLs). This sample comprises 19 High-energy cutoff BL Lacs objects (HBLs), 1 Low-energy cutoff BL Lac object (LBL) and 2…
A simple model for variability in relativistic plasma outflows is studied, in which nonthermal electrons are continuously and uniformly injected in the comoving frame over a time interval dt. The evolution of the electron distribution is…
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…
The standard blazar paradigm consists of a supermassive black hole that expels relativistic jets of magnetized plasma in our direction. This plasma entrains nonthermal synchrotron-emitting electrons that furthermore scatter…
We calculate angular correlation function between ultra-high energy cosmic rays (UHECR) observed by Yakutsk and AGASA experiments, and most powerful BL Lacertae objects. We find significant correlations which correspond to the probability…
We have begun to examine the EGRET database for short term variations in the fluxes of blazars and unidentified sources at high Galactic latitude. We find that several AGN show previously unreported variability. Such variations are…
The spectral energy distribution of blazars around the synchrotron peak can be well described by the log-parabolic model that has three parameters: peak energy ($E_\textrm{p}$), peak luminosity ($L_\textrm{p}$) and the curvature parameter…
We find that energy losses due to synchrotron self-Compton (SSC) emission in blazar jets can produce distinctive signatures in the time-averaged synchrotron and SSC spectra of these objects. For a fairly broad range of particle injection…
Relativistic jets launched by rotating black holes are powerful emitters of non-thermal radiation. Extraction of the rotational energy via electromagnetic stresses produces magnetically-dominated jets, which may become turbulent. Studies of…