A close look at the black hole masses and hot dusty toruses of the first quasars with MIRI-MRS
Authors
Sarah E. I. Bosman
Javier Álvarez-Márquez
Frederick B. Davies
Klaudia Protušová
Joseph F. Hennawi
Jinyi Yang
Benedetta Spina
Luis Colina
Xiaohui Fan
Göran Östlin
Fabian Walter
Feige Wang
Martin Ward
Almudena Alonso Herrero
Aaron J. Barth
Silvia Belladitta
Leindert Boogaard
Karina I. Caputi
Thomas Connor
Dominika Ďurovčíková
Anna-Christina Eilers
Alejandro Crespo Gómez
Jens Hjorth
Hyunsung D. Jun
Danial Langeroodi
Weizhe Liu
Alessandro Lupi
Chiara Mazzucchelli
John P. Pye
Pierluigi Rinaldi
Paul van der Werf
Marta Volonteri
Abstract
The presence of supermassive black holes (SMBHs, $M_\text{BH}\sim10^9 M_\odot$) at $z>7$ remains a puzzle. While their existence appears to require exotic formation or growth processes, it is possible that BH mass estimates are incorrect due to differences from the low-$z$ quasars where BH mass scaling relations are calibrated. In this work, we employ JWST MIRI-MRS spectroscopy to measure the rest-frame optical/IR properties of the four highest-redshift known luminous type-1 quasars at $7.08\leq z<7.64$. We use three new broad lines to measure updated BH masses, H$α$, Pa$α$ and Pa$β$, finding them to be in the range $(4-15)\cdot10^8 M_\odot$. Our black hole mass estimates from all tracers agree with each other and with previous, less accurate, ground-based measurements based on MgII. The flux ratios of the H lines deviate from expectations for case A and B recombination in the same way as in $z<3$ quasars, indicating similar physical conditions in the Broad Line Region. Rest-frame near-IR continuum emission from a hot dusty torus surrounding the accretion disc is unambiguously detected in all four objects. We model the emission with SKIRTOR and constrain the inclination (face-on) and the opening angle ($θ=40-60^\circ$) of the tori. These constraints are consistent for the four objects and with expectations from luminous quasars. We estimate a total dust mass $(1-4)\cdot10^6 M_\odot$ in the tori, corresponding to $(0.2-7)\%$ of the total dust in the quasar host galaxies. Given observed accretion rates, these SMBHs will deplete their tori in only $\sim5$ Myr. Overall, we confirm that $z>7$ SMBHs in quasars could not have grown from stellar-remnant BHs if the radiative efficiency of accretion is $10\%$. We also find no evidence that inferred BH masses and accretion processes in $z>7$ quasars differ significantly from their near-identical counterparts at $z<3$.
