Related papers: Echo Mapping of AGN Emission Regions
Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the…
A long-standing question is whether active galactic nuclei (AGN) vary like Galactic black hole systems when appropriately scaled up by mass (refs 1-3). If so, we can then determine how AGN should behave on cosmological timescales by…
Continuum reverberation mapping (RM) is a powerful technique for constraining the accretion disk structure in active galactic nuclei (AGNs). In typical cases, the shorter-wavelength emission is used as the reference, and a positive time lag…
We study the narrow emission line properties and stellar populations of a sample of 1385 AGN selected to have strong excess emission at mid-infrared wavelengths based on comparing Wide-field Infrared Survey Explorer W1-W2 band colours with…
A crucial difficulty in understanding the nature of the putative accretion disk in AGNs is that some of its key intrinsic spectral signatures cannot be observed directly. The strong emissions from the broad-line region (BLR) and the…
AGNs exhibit a wide range of black hole masses and inflow/outflow properties. It is now possible to probe regions close to the event horizons of nearby SMBHs using VLBI with earth-sized baselines, as performed by the EHT. This study…
Low-mass black holes hosted by dwarf galaxies offer valuable insights into galaxy formation and the growth of the massive black holes found in massive galaxies. Their detection as AGN is challenging due to their low luminosity and compact…
The majority of nearby radio-loud AGN are found in massive, old elliptical galaxies with weak emission lines. At high redshifts,however, most known radio AGN have strong emission lines. In this paper, we examine a subset of radio AGN with…
Spectral Energy Distribution (SED) of the broad-band continuum emission from black-hole accretion discs can serve as a tool to measure parameters of the central body and constrain the geometry of the inner accretion flow. We focus on the…
This contribution briefly reviews the reverberation mapping technique which leads to determination of black hole masses. I focus on the emerging relation between the broad-line region size and the active galactic nucleus (AGN) luminosity,…
We study the optical variability characteristics of Active Galactic Nuclei (AGN) from the Swift Burst Alert Telescope (BAT) AGN catalogue by utilising approximately five years of optical light curves from the Zwicky Transient Facility (ZTF)…
Most of the action in Active Galactic Nuclei (AGN) occurs within a few tens of gravitational radii from the supermassive black hole, where matter in the accretion disk may lose up to almost half of its energy with a copious production of…
Any cold, optically-thick matter in the vicinity of an accreting black hole, such as the accretion disk, can intercept and reprocess some fraction of the hard X-ray continuum emission, thereby imprinting atomic features into the observed…
Radiation from the blazar class of of active galactic nuclei (AGN) exhibits fast time variability which is usually ascribed to instabilities in the emission region near the central supermassive black hole. The variability time scale is…
Spectral-timing techniques have proven valuable in studying the interplay between the X-ray corona and the accretion disc in variable active galactic nuclei (AGN). Under certain conditions, photo-ionized outflows emerging from central AGN…
The supermassive black holes in active galactic nuclei (AGN) and stellar-mass black holes in X-ray binaries (XRBs) are believed to work in a similar way. While XRBs evolve rapidly and several sources have undergone a few complete cycles…
A major amendment in recent models of hierarchical galaxy formation is the inclusion of so-called AGN feedback. The energy input from an active central massive black hole is invoked to suppress star formation in early-type galaxies at later…
The flux variations in the emission lines in active galactic nuclei (AGNs) are driven by variations in the ionizing continuum flux --which are usually reflected in the observable UV-optical continuum. The "Reverberation mapping" technique…
We investigate the accretion disk geometry in Galactic black hole sources by measuring the time delay between soft and hard X-ray emissions. Similar to the recent discoveries of anti-correlated hard X-ray time lags in Cyg X-3 and GRS…
The relativistically broad X-ray iron line seen in many AGN spectra is thought to originate from the central regions of the putative black hole accretion disk. Both the line profile and strength will vary in response to rapid variability of…