Silicate emission in a type-2 quasar: JWST/MIRI constraints on torus geometry and radiative feedback
Year: 2025
Type: article
Abstract: Type-2 quasars (QSO2s) are active galactic nuclei (AGN) seen through a significant amount of dust and gas that obscures the central supermassive black hole and the broad line region. Despite this, recent mid-infrared spectra of the central 0.5–1.1 kpc of five QSO2s at z ∼ 0.1, obtained with the MRS module of JWST/MIRI, revealed 9.7, 18, and 23 μm silicate features in emission in two of them. This indicates that the high angular resolution of JWST/MIRI now allows us to peer into their nuclear region, exposing some of the directly illuminated dusty clouds that produce silicate emission. To test this, we fit the nuclear mid-infrared spectrum of the QSO2 with the strongest silicate features, J1010, with two different sets of torus models implemented in an updated version of the Bayesian tool BayesClumpy . These are the CLUMPY and the CAT3D-WIND models. The CAT3D-WIND model is preferred by the observations based on the marginal likelihood and fit residuals, although the two torus models successfully reproduce the spectrum by means of intermediate covering factors (C T = 0.45± 0.26 −0.18 and C T = 0.66± 0.16 −0.17 for the CLUMPY and CAT3D-WIND models) and low inclinations ( i = 50°± 8° 9° and i = 13°± 7° 6° ). Indeed, four of the five QSO2s with JWST/MIRI observations, including J1010, are in the blowout or “forbidden” region of the Eddington ratio-column density diagram, indicating that they are actively clearing gas and dust from their nuclear regions, leading to reduced covering factors. This is in contrast with Seyfert 2 galaxies observed with JWST, which are in the “permitted” regions of the diagram and show 9.7 μm silicate features in absorption. This supports a scenario where the more luminous the AGN and the higher their Eddington ratio, the lower the torus covering factor, driven by radiation pressure on dusty gas.
Source: Astronomy and Astrophysics
Institutions: Universidad de La Laguna, Instituto de Astrofísica de Canarias, Consejo Superior de Investigaciones Científicas, Centro de Astrobiología, University of South Carolina, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, University of Southampton, Spanish National Observatory, Instituto de Física Fundamental, University of California San Diego, Universidad Nacional Autónoma de México, Space Telescope Science Institute, University of Oxford, University of Sheffield
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Aeronautics and Space Administration, Comunidad de Madrid, Space Telescope Science Institute, Government of the United Kingdom, UK Research and Innovation, Ministerio de Ciencia, Innovación y Universidades, European Space Agency, European Commission, Max-Planck-Gesellschaft, Centre National de la Recherche Scientifique, HORIZON EUROPE Framework Programme, Science and Technology Facilities Council, European Regional Development Fund, Agencia Estatal de Investigación, Astrophysics Division
Awards: G103270039, G1338664626, G1622782223, G2262748287, G2351152971, G256731684, G3355798522, G3480869486, G3681454997, G4042783231, G425668148, G451917667, Towards dynamical black hole masses at cosmic noon, G5380678141, G5568641063, G5677826004, G5852004334, G586857820, G5967599077, G6329169236, G6640210566, Excellence in Galaxies - Twinning the IAC, G7084143925, G7863371703, G7867642008, G8083530641, G8104139569, G8497050386
OpenAlex ID: W4417474301