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

We present new insights into the dusty environments of type-2 quasars (QSO2s) enabled by mid-infrared spectroscopy from JWST/MIRI. The mid-infrared spectra of five optically selected QSO2s at z~0.1 reveal the presence of 9.7, 18, and 23 μm silicate features in emission in two objects, challenging the classical picture of obscured AGN showing silicate absorption. The high angular resolution of JWST/MIRI allows us to isolate the nuclear regions where directly illuminated dusty clouds produce these emission features. We focus on the QSO2 with the strongest silicate emission, fitting its nuclear mid-IR spectrum with the CLUMPY and CAT3D-WIND torus models. Both models reproduce the spectrum with intermediate torus covering factors and inclination angles, with a preference for the disk+wind geometry of CAT3D-WIND. Furthermore, four of the five QSO2s fall in the "blowout" region of the Eddington ratio–column density plane, consistent with active clearing of nuclear dust by radiation pressure in these objects. This contrasts with Seyfert 2 galaxies, which remain in "permitted" regions and typically show silicate 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.