We investigate the attenuation law in z ∼6 quasars by combining cosmological zoom-in hydrodynamical simulations of quasar host galaxies, with multifrequency radiative transfer calculations. We consider several dust models differing in terms of grain-size distributions, dust mass, and chemical composition, and compare the resulting synthetic spectral energy distributions with data from bright, early quasars. We show that only dust models with grain-size distributions in which small grains (a ≤ 0.1 μm, corresponding to ≈ of the total dust mass) are selectively removed from the dusty medium provide a good fit to the data. Removal can occur if small grains are efficiently destroyed in quasar environments and/or early dust production preferentially results in large grains. Attenuation curves for these models are close to flat, and consistent with recent data; they correspond to an effective dust-to-metal ratio fd ~ 0.38, i.e. close to the Milky Way value.

The dust attenuation law in z~6 quasars

S Gallerani;A Ferrara;A Pallottini;S Carniani;
2021

Abstract

We investigate the attenuation law in z ∼6 quasars by combining cosmological zoom-in hydrodynamical simulations of quasar host galaxies, with multifrequency radiative transfer calculations. We consider several dust models differing in terms of grain-size distributions, dust mass, and chemical composition, and compare the resulting synthetic spectral energy distributions with data from bright, early quasars. We show that only dust models with grain-size distributions in which small grains (a ≤ 0.1 μm, corresponding to ≈ of the total dust mass) are selectively removed from the dusty medium provide a good fit to the data. Removal can occur if small grains are efficiently destroyed in quasar environments and/or early dust production preferentially results in large grains. Attenuation curves for these models are close to flat, and consistent with recent data; they correspond to an effective dust-to-metal ratio fd ~ 0.38, i.e. close to the Milky Way value.
Settore FIS/05 - Astronomia e Astrofisica
Dust, extinction; Galaxies: ISM; Methods: numerical; Quasars: general; Radiative transfer;
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/105005
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