相关论文: Kepler Observations of Rapid Optical Variability i…

Radiation emitted from an accretion disk around a massive black hole is a widely discussed model for the UV/soft X-ray excess emission observed in the spectra of many AGN. A self-consistent calculation of the structure and the emerging…

The morphological study is crucial to investigate the connections between active galactic nuclei (AGN) activities and the evolution of galaxies. Substantial studies have found that radiative-mode AGNs primarily reside in disk galaxies,…

A key feature of active galactic nuclei (AGN) is their variability across all wavelengths. Typically, AGN vary by a few tenths of a magnitude or more over periods lasting from hours to years. By contrast, extreme variability of AGN -- large…

We present results from a study to detect variable galaxies in the Hubble Deep Field North. The goal of this project is to investigate the number density of AGN at z=1 through the detection of variable galaxy nuclei. The advantage of HST is…

We present spectra of the nuclear regions of 50 nearby (D = 1 - 92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength…

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…

We analyze the broadband photometric light curves of Seyfert 1 galaxies from the Sergeev et al. (2005) sample and find that a) perturbations propagating across the continuum emitting region are a general phenomenon securely detected in most…

We present a new determination of the optical luminosity function (OLF) of active galactic nuclei (AGN) at low redshifts (z<0.15) based on Hubble Space Telescope (HST) observations of X-ray-selected AGN. The HST observations have allowed us…

We develop a new spectral model for the broadband spectral energy distribution (SED) of Active Galactic Nuclei (AGN). This includes an outer standard disc, an inner warm Comptonising region to produce the soft X-ray excess and a hot corona.…

The James Webb Space telescope has discovered an abundant population of broad line emitters, typical signposts for Active Galactic Nuclei (AGN). Many of these sources have red colors and a compact appearance that has led to naming them…

The X-ray spectra of Active Galactic Nuclei (AGN) are complex and vary rapidly in time as seen in recent observations. Magnetic flares above the accretion disk can account for the extreme variability of AGN. They also explain the observed…

The origin of the observed time lags, in nearby active galactic nuclei (AGN), between hard and soft X-ray photons is investigated using new XMM-Newton data for the narrow-line Seyfert I galaxy Ark 564 and existing data for 1H0707-495 and…

Surveys of Active Galactic Nuclei (AGN) in different observational regimes seem to give different answers for the behaviour of the obscured fraction with luminosity. Based on the complex spectra seen in recent studies, we note that partial…

We have obtained new spectropolarimetric observations at visible wavelengths of the changing-look active galactic nucleus (AGN) Mrk 1018. The AGN direct spectrum shows an extremely weak continuum with faint broad H$\beta$ and H$\alpha$…

The Swift Burst Alert Telescope (BAT) survey of Active Galactic Nuclei (AGN) is providing an unprecedented view of local AGNs (<z> = 0.03) and their host galaxy properties. In this paper, we present an analysis of the optical spectra of a…

The precision measurements of the spectra of cosmic ray nuclei and leptons in recent years have revealed the existence of multiple features, such as the spectral break at $\sim 300$ GV rigidity seen by PAMELA and AMS-02 and more recently…

The discovery of changing-look active galactic nuclei (CL AGNs), with appearance and disappearance of broad emission lines and/or with strong variation of line-of-sight column density within a few years, challenges the AGN unification…

We present the identification of changing-look active galactic nuclei (CL-AGNs) from the Dark Energy Spectroscopic Instrument First Data Release and Sloan Digital Sky Survey Data Release 16 at z \leq 0.9. To confirm the CL-AGNs, we utilize…

In this work, which is a continuation of Castell\'o-Mor et al. (2016), we present new X-ray and infrared (IR) data for a sample of active galactic nuclei (AGN) covering a wide range in Eddington ratio over a small luminosity range. In…

We present a systematic X-ray and multiwavelength study of a sample of 47 active galactic nuclei (AGNs) with reverberation-mapping measurements. This sample includes 21 super-Eddington accreting AGNs and 26 sub-Eddington accreting AGNs.…