Related papers: The Evolution of the BL Lacertae Objects
Fermi has provided the largest sample of gamma-ray selected blazars to date. In this work we use a uniformly selected set of 211 BL Lacertae (BL Lac) objects detected by it Fermi during its first year of operation. We have obtained redshift…
The Blandford-Znajek (BZ) process is a pivotal mechanism to efficiently extract the energy from a rotating black hole (BH) via its plasma-filled magnetosphere in relativistic astrophysics. Within the framework of extended BZ monopole…
The past 20 years have seen phenomenal progress in our understanding of BL Lac objects. They form part of the blazar class, which are radio-loud AGN whose relativistic jets are aligned along our line of sight. Several critical milestones…
BL Lacertae is the prototype of the BL Lac class of active galactic nuclei, exhibiting intensive activity on parsec (pc) scales, such as intense core variability and multiple ejections of jet components. In particular, in previous works the…
The most elusive and extreme sub-class of active galactic nuclei (AGNs), known as BL Lac objects, shows features that can only be explained as the result of relativistic effects occurring in jets pointing at a small angle with respect to…
Blazars, a subclass of radio-loud active galactic nuclei with relativistic jets aligned close to our line of sight, emit highly variable non-thermal radiation across the electromagnetic spectrum. The physical origin of their emission and…
Recent work on the engines of active galactic nuclei jets suggests their power depends strongly and perhaps counter-intuitively on black hole spin. We explore the consequences of this on the radio-loud population of active galactic nuclei…
We calculate the jet power of the Blandford-Znajek (BZ) model and the hybrid model based on the self-similar solution of advection-dominated accretion flows (ADAFs). We study the formation mechanism of the jets of BL Lacs with known…
We present an analysis of the spectral properties observed in X-rays from active galactic nucleus BL Lacertae using RXTE, Suzaku, ASCA, BeppoSAX, and Swift observations. The total time covered by these observations is approximately 20…
The Blandford-Znajek mechanism has long been regarded as a key ingredient in models attempting to explain powerful jets in AGNs, quasars, blazzars etc. In such mechanism, energy is extracted from a rotating black hole and dissipated at a…
One of the leading mechanisms powering relativistic black hole jets is the Blandford-Znajek (BZ) process. Inspired by its success we construct energy extracting models for black holes in five space-time dimensions. Here, we find solutions…
Blazars are a sub-category of radio-loud active galactic nuclei with relativistic jets pointing towards the observer. They exhibit non-thermal variable emission, which practically extends over the whole electromagnetic spectrum. Despite the…
The relation between accretion disc (thermal emission) and jet (non-thermal emission) in blazars is still a mystery as, typically, the beamed jet emission swamps the disc even in the ultraviolet band where disc emission peaks. In this paper…
Is it significant that the intrinsic outputs of several BL Lacs are observed to level off at values of about 10^46 erg s^-1? In searching for an answer, we compare gamma-ray observations by the AGILE satellite of the BL Lac S5 0716+714 with…
The Blandford-Znajek (BZ) process is steady electromagnetic energy release from rotating black holes (BHs) along magnetic field lines threading them and widely believed to drive relativistic jets. This process is successfully demonstrated…
The Blandford-Znajek theory (1977) is generally studied to understand the generation of powerful relativistic jets. However, it could also give important insights about the feedback between a rotating black hole, its ergosphere, and a…
We study scalar field configurations around Kerr black holes with a time-independent energy-momentum tensor. These stationary `scalar clouds', confined near the black hole (BH) by their own mass or a mirror at fixed radius, exist at the…
We use data from the Wide-Field Infrared Survey Explorer (WISE) to perform a statistical study on the mid-infrared (IR) properties of a large number ($\sim10^2$) of BL Lac objects --- low-luminosity Active Galactic Nuclei (AGN) with a jet…
We report stellar velocity dispersion measurements for a sample of 28 AGN host galaxies including our previous work. Using the mass-dispersion ($M_{\bullet}-\sigma$) and the fundamental plane relations, we estimate the black hole mass for a…
The $Fermi$ blazar observations show a strong correlation between $\gamma$-ray luminosities and spectral indices. BL Lac objects are less luminous with harder spectra than flat-spectrum radio quasars (FSRQs). Interestingly FSRQs are evident…