Related papers: The Changing-Look Quasar Mrk 590 is Awakening

We report the discovery of eight new recurrent changing-look (CL) active galactic nuclei (AGNs), including seven re-brightening turn-off AGNs and one fading turn-on AGN. These systems are valuable for placing constraints on the duration of…

To date, a number of changing-look (CL) active galactic nuclei (AGNs) are known. We studied, in detail what happens to the X-ray spectrum during the CL events using the example of the nearby CL Seyfert NGC1566, which was observed by Swift,…

Active Galactic Nuclei (AGN) have long been known to be variable, but the amplitude, timescale and nature of these changes can often differ dramatically from object to object. The richest source of information about the properties of AGN…

We analyze the X-ray, optical, and mid-infrared data of a "changing-look" Seyfert galaxy \sdssj15 at $z\simeq0.086$. Over a period of one decade (2009 - 2018), its broad H$\alpha$ line intensity increased by a factor of $\sim$4. Meanwhile,…

The evolutionary role of the so-called ``changing-look'' (CL) active galactic nucleus (AGN), which is characterized by spectral-type transitions within $\sim10$ yr, has been suggested in the past few years. By focusing on CL-AGNs having…

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 Seyfert 1 galaxy, Ark 120, is a prototype example of the so-called class of bare nucleus AGN, whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep ($>400$ ks exposure), high…

We report the discovery of a triply imaged active galactic nucleus (AGN), lensed by the galaxy cluster MACS J0035.4-2015 ($z_{\mathrm{d}}=0.352$). The object is detected in Hubble Space Telescope imaging taken for the RELICS program. It…

Active galactic nuclei (AGN) are known to be variable sources across the entire electromagnetic spectrum, in particular at optical/ultraviolet and X-ray energies. Over the past decades, a growing number of AGN have displayed type…

This paper reports on a partially simultaneous observation of the bright Seyfert 1 Galaxy Mrk590, performed by XMM-Newton and Chandra. The long exposure (~100 ks) allows to investigate with great detail the Fe K complex at 6-7 keV and the…

We report the discovery that the known `changing look' AGN Mrk 1018 has changed spectral type for a second time. New VLT-MUSE data taken in 2015 as part of the Close AGN Reference Survey (CARS) shows that the AGN has returned to its…

It is widely expected that the obscured accretion stage can be the initial turning-on stage of active galactic nuclei from quiescent galaxies. We present mid-infrared light curves of NGC 6447 in 3.5$\mu$m and 4.6 $\mu$m bands observed by…

"Changing-look" active galactic nuclei (CL-AGNs) challenge our basic ideas about the physics of accretion flows and circumnuclear gas around supermassive black holes. Using first-year Sloan Digital Sky Survey V (SDSS-V) repeated…

We present an analysis of historical multi-wavelength emission of the Changing Look (CL) Active Galactic Nucleus (AGN) in NGC 2992, covering epochs ranging from 1978 to 2021, as well as new X-ray and optical spectra. The galaxy presents…

Active galactic nuclei (AGNs) are known to exhibit optical/UV variability and most of them can be well modeled by the damped random walks. Physical processes that are not related to the accretion disk, such as tidal disruption events (TDE)…

KUG 1141+371 is a Seyfert 1 galaxy that shows a simultaneous flux increase in the optical and UV bands in the past decade. For instance, the latest Swift observation in 2019 shows that the UVW2 flux of the AGN in KUG 1141+371 has increased…

Here we report an identification of B3\,0749+460A as a new double-peaked local "changing-look" active galactic nucleus (CL-AGN) in terms of our multi-epoch spectroscopic analysis. By comparing our new spectra taken in 2021 with the ones…

We present a thorough study of the Changing-Look Active Galactic Nucleus (CL-AGN) Mrk 1018, utilizing an extensive dataset spanning optical, UV, and X-ray spectro-photometric data from 2005 to 2019. We analysed X-ray spectra and broad-band…

We present the results of five NuSTAR observations of the type 2 active galactic nucleus (AGN) in IC 751, three of which were performed simultaneously with XMM-Newton or Swift/XRT. We find that the nuclear X-ray source underwent a clear…

We examine the long-term optical/near-infrared (NIR) flux variability of a "changing-look" active galactic nucleus (AGN) Mrk 590 between 1998 and 2007. Multi-band multi-epoch optical/NIR photometry data from the SDSS Stripe 82 database and…