Silicate emission in a type-2 quasar: JWST/MIRI constraints on torus geometry and radiative feedback

¹ Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n E-38205 La Laguna Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna E-38206 La Laguna Tenerife, Spain
³ Centro de Astrobiología (CAB), CSIC-INTA Camino Bajo del Castillo s/n E-28692 Villanueva de la Cañada Madrid, Spain
⁴ Department of Physics & Astronomy, University of South Carolina Columbia SC 29208, USA
⁵ Kavli Institute for Particle Astrophysics & Cosmology (KIPAC), Stanford University Stanford CA 94305, USA
⁶ School of Physics & Astronomy, University of Southampton Highfield Southampton SO171BJ, UK
⁷ Observatorio Astronómico Nacional (OAN-IGN)-Observatorio de Madrid, Alfonso XII 3 28014 Madrid, Spain
⁸ Instituto de Física Fundamental, CSIC Calle Serrano 123 28006 Madrid, Spain
⁹ Department of Astrophysics, University of California San Diego 9500 Gilman Drive San Diego CA 92093, USA
¹⁰ Instituto de Radioastronomía and Astrofísica (IRyA-UNAM) 3-72 (Xangari) 8701 Morelia, Mexico
¹¹ Space Telescope Science Institute Baltimore MD 21218, USA
¹² Department of Physics, University of Oxford Oxford OX1 3RH, UK
¹³ Department of Physics & Astronomy, University of Sheffield S3 7RH Sheffield, UK

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Received: 19 September 2025
Accepted: 30 November 2025

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.