Rapid, large amplitude variability at optical to X-ray wavelengths is now seen in an increasing number of Seyfert galaxies and luminous quasars. The variations imply a global change in accretion power, but are too rapid to be communicated by inflow through a standard thin accretion disc. Such discs are long known to have difficulty explaining the observed optical/UV emission from active galactic nuclei. Here we show that alternative models developed to explain these observations have larger scale heights and shorter inflow times. Accretion discs supported by magnetic pressure in particular are geometrically thick at all luminosities, with inflow times as short as the observed few year timescales in extreme variability events to date. Future time-resolved, multi-wavelength observations can distinguish between inflow through a geometrically thick disc as proposed here, and alternative scenarios of extreme reprocessing of a central source or instability-driven limit cycles.
Aims. Active galactic nuclei (AGNs) with EUV deficit are suggested to be powered by a MAD surrounding the black hole, where the slope of EUV spectra ($α_{\rm EUV}$) is found to possess a well positive relationship with the jet efficiency. In this work, we investigate the properties of X-ray emission in AGNs with EUV deficit for the first time. Methods. We construct a sample of 15 objects with EUV deficit to analyse their X-ray emission. The X-ray luminosity in 13 objects are newly processed by ourself, while the other 2 sources are gathered from archival data. Results. It is found that the ave…
The extent of black hole growth during different galaxy evolution phases and the connection between galaxy compactness and AGN activity remain poorly understood. We use Hubble Space Telescope imaging of the CANDELS fields to identify star-forming and quiescent galaxies at z=0.5-3 in both compact and extended phases and use Chandra X-ray imaging to measure the distribution of AGN accretion rates and track black hole growth within these galaxies. Accounting for the impact of AGN light changes ~20% of the X-ray sources from compact to extended galaxy classifications. We find that ~10-25% of compa…
Multi-wavelength observations suggest that the accretion disk in the hard and intermediate states of X-ray binaries (XRBs) and active galactic nuclei (AGN) transitions from a cold, thin disk at large distances into a hot, thick flow close to the black hole. However, the formation, structure and dynamics of such truncated disks are poorly constrained due to the complexity of the thermodynamic, magnetic, and radiative processes involved. We present the first radiation-transport two-temperature general relativistic magnetohydrodynamic (GRMHD) simulations of truncated disks radiating at ~35% of th…
We investigate the role of galaxy mergers on supermassive black hole (SMBH) accretion and star formation quenching in three state-of-the-art cosmological simulations with contrasting physics models: EAGLE, Illustris and IllustrisTNG. We find that recently coalesced 'post-mergers' in all three simulations have elevated SMBH accretion rates by factors of ~2-5. However, rapid (within 500 Myr of coalescence) quenching of star formation is rare, with incidence rates of 0.4% in Illustris, 4.5% in EAGLE and 10% in IllustrisTNG. The rarity of quenching in post-mergers results from substantial gas rese…
AGN obscuration in optical and X-rays: Host properties and the interplay of nuclear and galactic gas and dust in a combined SDSS-XMM sample
Instituto de Física de Cantabria (CSIC–Universidad de Cantabria)（坎塔布里亚物理研究所（西班牙科学研究中心-坎塔布里亚大学））；European Space Agency (ESA), European Space Astronomy Centre (ESAC)（欧洲空间局（ESA），欧洲空间天文中心（ESAC））；Department of Astronomy, University of Geneva（日内瓦大学天文学系）；INAF–Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；University of Helsinki（赫尔辛基大学）；IRAP, Université de Toulouse, CNRS, UPS, CNES（图卢兹大学 IRAP 研究所（CNRS、UPS、CNES））
We present results from the James Webb Space Telescope (JWST) Director's Discretionary Time Early Release Science (ERS) program 1328 targeting the nearby, Luminous Infrared Galaxy (LIRG), VV 114. We use the MIRI and NIRSpec instruments to obtain integral-field spectroscopy of the heavily obscured Eastern nucleus (V114E) and surrounding regions. The spatially resolved, high-resolution, spectra reveal the physical conditions in the gas and dust over a projected area of 2-3 kpc that includes the two brightest IR sources, the NE and SW cores. Our observations show for the first time spectroscopic …
Sparks: The Magellan/FIRE survey from starburst to post-starburst
Kavli Institute for Particle Astrophysics & Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理与宇宙学研究所）；Center for Decoding the Universe, Stanford University（斯坦福大学解码宇宙中心）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理科学系）；Department of Astronomy and Astrophysics, University of California Santa Cruz（加州大学圣克鲁兹分校天文与天体物理系）；Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)（宇宙物理与数学卡弗里研究所）；Division of Science, National Astronomical Observatory of Japan（日本国立天文台科学部）；Department of Physics and Astronomy, University of California, Riverside（加州大学河滨分校物理与天文系）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）
