Warm absorbers: supermassive black hole feeding, and Compton-thick AGN

Abstract

Warm absorbers are found in many AGN and consist of clouds moving at moderate radial velocities, showing complex ionization structures and having moderate to large column densities. Using 1D numerical calculations, we confirm earlier suggestions that the energy released by an AGN pushes the surrounding gas outward in a bubble until this reaches transparency. Typical AGN episode durations of $5\times 10^4$ yr supply enough energy for this, except in very gas-rich and/or very compact galaxies, such as those in the early Universe. In those galaxies, the AGN might remain hidden for many periods of activity, hiding the black hole growth. The typical radii of $0.1-1$ kpc, velocities of $100-1000$ km s${}^{-1}$ and resulting optical depths are consistent with observations of warm absorbers. The resulting structure is a natural outcome of outflows driven by AGN buried in an optically thick gas envelope, and has a total mass comparable to the final $M-\sigma$ mass the central supermassive black hole will eventually reach.These results suggest that AGN can feed very efficiently by agitating this surrounding dense material. This may not be easy to observe, as this gas is Compton thick along many sightlines. The infall may produce episodic star formation in the centre, building up nuclear star clusters simultaneously with the growth of the central black hole.

9 pages, 4 figures; accepted for publication in MNRAS

References in corpus (18)

• A luminous quasar at a redshift of z = 7.085
• Formation of Supermassive Black Holes by Direct Collapse in Pregalactic Halos
• Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS
• Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy
• Super-Critical Growth of Massive Black Holes from Stellar-Mass Seeds
• Very extended cold gas, star formation and outflows in the halo of a bright QSO at z>6
• A spectral-timing model for ULXs in the super-critical regime
• On the Fraction of Quasars with Outflows
• Fuelling Active Galactic Nuclei
• Ultra-fast outflows in radio-loud active galactic nuclei
• The origin of fast molecular outflows in quasars: molecule formation in AGN-driven galactic winds
• Compton Thick AGN in the XMM-COSMOS survey
• Energy- and momentum-conserving AGN feedback outflows
• The NuSTAR Serendipitous Survey: Hunting for The Most Extreme Obscured AGN at >10 keV
• How the central black hole may shape its host galaxy through AGN feedback
• The small observed scale of AGN--driven outflows, and inside--out disc quenching
• Massive outflow properties suggest AGN fade slowly
• Geometrical beaming of stellar mass ULXs

Cited by in corpus (5)

• Ionized outflows from active galactic nuclei as the essential elements of feedback
• Supermassive Black Hole Winds in X-rays -- SUBWAYS. III. A population study on ultra-fast outflows
• Determining AGN luminosity histories using present-day outflow properties: a neural-network based approach
• Jet collision with accreting tori around SMBHs. GRHD and light surfaces constraints in aggregates of misaligned tori
• Infrared Spectroscopy of Nearby Radio Active Early-Type Galaxies -- II: Spectral Atlas