Radiation pressure confinement -- V. The predicted free-free absorption and emission in active galactic nuclei

Abstract

The effect of radiation pressure compression (RPC) on ionized gas in Active Galactic Nuclei (AGN) likely sets the photoionized gas density structure. The photoionized gas free-free absorption and emission are therefore uniquely set by the incident ionizing flux. We use the photoionization code Cloudy RPC model results to derive the expected relations between the free-free emission and absorption properties and the distance from the AGN centre, for a given AGN luminosity. The free-free absorption frequency of RPC gas is predicted to increases from $\sim$100 MHz on the kpc scale, to $\sim$100 GHz on the sub-pc scale, consistent with observations of spatially resolved free-free absorption. The free-free emission at 5 GHz is predicted to yield a radio loudness of $R\sim 0.03$, below the typical observed values of $R\sim 0.1-1$ in radio-quiet AGN. However, the flat free-free radio continuum may become dominant above 100 GHz. The suggested detection of optically thin free-free emission in NGC 1068, on the sub pc torus scale, is excluded as the brightness temperature is too high for optically thin free-free emission. However, excess emission observed with ALMA above 150 GHz in NGC 1068, is consistent with the predicted free-free emission from gas just outside the broad line region, a region which overlaps the hot dust disc resolved with GRAVITY. Extended $\sim$100 pc scale free-free emission is also likely present in NGC 1068. Future sub mm observation of radio quiet AGN with ALMA may allow to image the free-free emission of warm photoionized gas in AGN down to the 30 mas scale, including highly absorbed AGN.

18 pages, 13 figures; accepted for publication in MNRAS

References in corpus (20)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• The 2013 Release of Cloudy
• BAT AGN Spectroscopic Survey I: Spectral Measurements, Derived Quantities, and AGN Demographics
• On the origin of radio emission in radio quiet quasars
• Extragalactic Peaked-Spectrum Radio Sources at Low Frequencies
• Dust inflated accretion disc as the origin of the Broad Line Region in Active Galactic Nuclei
• An image of the dust sublimation region in the nucleus of NGC 1068
• The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and Stellar Dynamical Measurements
• Discovery of a new subparsec counterjet in NGC 1275: the inclination angle and the environment
• Radiation pressure confinement - IV. Application to broad absorption line outflows
• Radiation Pressure Confinement -- III. The origin of the broad ionization distribution in AGN outflows
• Unveiling the Nature of Coronae in Active Galactic Nuclei through Sub-mm Observations
• Evidence for Radiation Pressure Compression in the X-ray Narrow Line Region of Seyfert galaxies
• The post-Herschel view of intrinsic AGN emission: constructing templates for galaxy and AGN emission at IR wavelengths
• Simultaneous Millimeter-wave and X-ray monitoring of the Seyfert Galaxy NGC 7469
• Imaging the AGN Torus in Cygnus
• From radio-quiet to radio-silent: low luminosity Seyfert radio cores
• Extragalactic radio sources with sharply inverted spectrum at metre wavelengths
• Spatially-resolved UV diagnostics of AGN feedback: radiation pressure dominates in a prototypical quasar-driven superwind
• GMRT observations of extragalactic radio sources with steeply inverted spectra

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• Daily variability at milli-arcsecond scales in the radio quiet NLSy1 Mrk 110
• The radio properties of the JWST-discovered AGN
• Dusty plasma in active galactic nuclei
• Joint ALMA/X-ray monitoring of the radio-quiet type 1 AGN IC 4329A
• Radio spectra of narrow-line Seyfert 1 galaxies observed with ATCA and VLASS
• The Centimeter to Submillimeter Broad Band Radio Spectrum of the Central Compact Component in A Nearby Type-II Seyfert Galaxy NGC 1068
• Radio observations of four active galactic nuclei hosting intermediate-mass black hole candidates: studying the outflow activity and evolution
• ALMA observation of evolving magnetized corona in the radio-quiet changing-state AGN NGC 1566
• Detection of millimeter-wave coronal emission in a quasar at cosmological distance using microlensing
• Detection of extended millimeter emission in the host galaxy of 3C273 and its implications for QSO feedback via high dynamic range ALMA imaging
• Shedding the envelope: JWST reveals a kiloparsec-scale [OIII]-weak Balmer shell around a z=7.64 quasar
• Investigating the origin of radio emission in candidate super-Eddington accreting black holes
• Implication of a galaxy-scale negative feedback by one of the most powerful multi-phase outflows in a hyper-luminous infrared galaxy at the intermediate redshift
• Solving the multi-messenger puzzle of the AGN-starburst composite galaxy NGC 1068
• The core starbursts of the galaxy NGC 3628: Radio very long baseline interferometry and X-ray studies