Related papers: The characteristics of variability of AGNs based o…
Knowing the site of gamma-ray emission in AGN jets will do much for our understanding of the physics of the source. In particular, if the emission region is close to the black hole then absorption of gamma-rays with photons from the…
Very long baseline interferometry (VLBI) observations show that some active galactic nuclei (AGN) jets exhibit bending even at parsec scales. The nature of bending is comprehensively analysed only for a small number of individual AGN, and…
Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the POLAMI program, we have conducted 14 years of 1 mm and 3 mm…
The origin of the Fermi bubbles and the microwave haze is yet to be determined. To disentangle different models requires detailed comparisons between theoretical predictions and multi-wavelength observations. Our previous simulations have…
We present cross-correlation studies of gamma-ray (0.1-300 GeV), X-ray (0.2-10 keV) and optical (R-band) variability of a sample of 26 blazars during 2008-2016. The light curves are from Fermi-LAT, Swift-XRT, and the Yale-SMARTS blazar…
Flat Spectrum Radio Quasars (FSRQs) and BL Lac objects detected in the first three months of the Fermi survey neatly separate in the gamma-ray spectral index vs gamma-ray luminosity plane. BL Lac objects are less luminous and have harder…
Blazars present highly variable $\gamma$-ray emission. This variability, which can range from a few minutes to several years, is also observed at other wavelengths across the entire electromagnetic spectrum. We make use of the first 12…
We report our identification of three gigaelectronvolt $\gamma$-ray sources, 4FGL J0502.6+0036, 4FGL J1055.9+6507, and 4FGL J1708.2+5519, as Active Galactic Nuclei (AGNs). They are listed in the latest Fermi-LAT source catalog as…
One of the most important problem of the blazar astrophysics is to understand the physical origin of the blazar sequence. In this study, we focus on the GeV gamma-ray variability of blazars and evolution perspective we search the relation…
We investigate the astrophysics of radio-emitting star-forming galaxies and ac- tive galactic nuclei (AGNs), and elucidate their statistical properties in the radio band including luminosity functions, redshift distributions, and number…
We present analysis of the light curve from the ROSAT HRI monitoring observations of the broad-line radio galaxy 3C 390.3. Observed every three days for about 9 months, this is the first well sampled X-ray light curve on these time scales.…
Information on the structure around active galactic nuclei (AGN) has long been derived from measuring lags in their varying light output at different wavelengths. In principle, infrared data would reach to larger radii, potentially even…
Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power…
We report on a detailed investigation of the gamma-ray emission from 18 broad line radio galaxies (BLRGs) based on two years of Fermi Large Area Telescope (LAT) data. We confirm the previously reported detections of 3C 120 and 3C 111 in the…
The Fermi Large Area Telescope (Fermi LAT) provides long term systematic monitoring observations of the gamma-ray emission from blazars. The variability properties and the correlation with other wavelength bands are important clues for the…
Identifying Active Galactic Nuclei (AGNs) through their X-ray emission is efficient, but necessarily biased against X-ray-faint objects. We aim to characterize this bias by comparing X-ray-selected AGNs to the ones identified through…
The survey of the COSMOS field by the VLT Survey Telescope is an appealing testing ground for variability studies of active galactic nuclei (AGN). With 54 r-band visits over 3.3 yr and a single-visit depth of 24.6 r-band mag, the dataset is…
We present statistical analyses of a large homogenous data sample of Fermi-detected blazars thoroughly studied in order to reassess the relationship between flat-spectrum radio quasars (FSRQs) and subclasses of BL Lacertae objects (BL Lacs)…
We analyze the X-ray properties for a sample of 23 high probability AGN candidates with ultraviolet variability identified in Wasleske et al. (2022). Using data from the Chandra X-ray Observatory and the XMM-Newton Observatory, we find…
We report detection of a line-like feature in the $\gamma$-ray spectrum of the blazar B0516$-$621, for which the data obtained with the Large Area Telescope onboard {\it Fermi Gamma-Ray Space Telescope (Fermi)} are analyzed. The feature is…