相关论文: The long-term millimeter activity of active galact…

Active Galactic Nuclei (AGNs) are characterized by strong temporal flux density variability across the electromagnetic spectrum, offering insights into the complex physical processes governing accretion and plasma outflows. To…

The flat spectrum radio quasar 3C~454.3 underwent an extraordinary outburst in December 2009 when it became the brightest gamma-ray source in the sky for over one week. Its daily flux measured with the Fermi Large Area Telescope at photon…

The X-ray, Ultraviolet, Optical emission from radio-quiet AGNs, black hole binaries, and other compact sources, in general, follow a lognormal flux distribution, a linear rms-flux relation, and a (broken) power-law power spectral densities…

The variability of active galactic nuclei (AGN) has long held the promise of shedding light on their detailed structure, and possibly other astrophysical phenonema. Different emission mechanisms lead to different patterns of variability in…

We present multiwavelength observations of 3C 454.3 from April 2008 to March 2010. The radio to optical data are mostly from the GASP-WEBT, UV and X-ray data from Swift, and gamma-ray data from the AGILE and Fermi satellites. We improved…

Motivated by theoretical expectations that Nuclear Star Clusters (NSCs) in galactic centers may provide a favorable environment for super-massive black holes to form and/or efficiently grow, we set out to measure the fraction of nearby…

We report the results of decade-long (2008-2018) $\gamma$-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, $\it{Fermi}$ and $\it{Swift}$ data, as well as polarimetric and spectroscopic data. The X-ray and…

We present the results of the optical identifications of a set of X-ray sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical data were obtained with Russian-Turkish 1.5-m Telescope (RTT150). Nine X-ray sources were…

We present a sample of 22 massive galaxies with stellar masses $>10^{10} M_{\odot}$ at $3<z<4$ with deep H and K-band high resolution spectra (R=3500-3000) from Keck/MOSFIRE and VLT/KMOS near-infrared spectrographs. We find a large fraction…

Active galactic nuclei (AGN) are believed to be the source of ultra high energy cosmic rays (UHECRs). Particles are assumed to be accelerated in the accretion disk and the plasma jets, produced due to conservation of angular momentum, to…

Here we present the results of the long-term (1995-2007) spectral monitoring of the broad line radio galaxy \object{3C~390.3}, a well known AGN with the double peaked broad emission lines, usually assumed to be emitted from an accretion…

In this paper, the second in a series investigating FR II radio galaxies at low frequencies, we use LOFAR and VLA observations between 117 and 456 MHz in addition to archival data to determine the dynamics and energetics of two radio…

We present a detailed temporal and spectral study of the blazar 3C\,279 using multi-wavelength observations from Swift-XRT, Swift-UVOT and Fermi-LAT during a flare in 2018 January. The temporal analysis of $\gamma$-ray light curve indicates…

The physical mechanism for triggering the changing-look phenomenon in active galactic nuclei (AGNs) is still unclear. We explore this issue based on the multi-wavelength spectral and flux variations for a changing-look AGN Mrk~1018 with…

Outflows of ionized gas driven by active galactic nuclei (AGN) may significantly impact the evolution of their host galaxies. However, determining the energetics of these outflows is difficult with spatially unresolved observations that are…

We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321. The flux of this source above 100 MeV is shown to be variable on time scales of days and months. Optical observations and careful examination of…

Blazars show optical and $\gamma$-ray flux variations that are generally correlated, although there are exceptions. Here we present anomalous behaviour seen in the blazar 3C 454.3 based on an analysis of quasi-simultaneous data at optical,…

We present high angular resolution radio snap-shot observations of seven nearby low-luminosity active galaxies (LLAGN) from the NUclei of GAlaxies (NUGA) survey. The observations were conducted with MERLIN and EVN/VLBI at 18cm and 6cm. At…

3C 454.3 is frequently observed in flaring state. The long term light curve of this source has been analysed with 9 year (August 2008 - July 2017) data from Fermi LAT detector. We have identified five flares and one quiescent state. The…

Characterisation of the long-term variations in the broad line region in a luminous blazar, where Comptonisation of broad-line emission within a relativistic jet is the standard scenario for production of gamma-ray emission that dominates…