Super-Eddington Accretion in the WISE-Selected Extremely Luminous Infrared Galaxy W2246-0526

TL;DR

This study investigates the super-Eddington accretion in the most luminous hot dust-obscured galaxy W2246-0526 at z=4.601, revealing a high black hole mass and Eddington ratio suggesting photon trapping effects.

Contribution

First measurement of black hole mass and accretion properties in W2246-0526, highlighting super-Eddington accretion and photon trapping in an extremely luminous galaxy.

Findings

Black hole mass of log(M_BH/M_sun)=9.6 ± 0.4

Eddington ratio of approximately 2.8

Evidence for photon trapping limiting luminosity growth

Abstract

We use optical and near-infrared spectroscopy to observe rest-UV emission lines and estimate the black hole mass of WISEA J224607.56-052634.9 (W2246-0526) at z = 4.601, the most luminous hot dust-obscured galaxy yet discovered by WISE. From the broad component of the MgII-2799A emission line, we measure a black hole mass of log (M_BH/M_sun) = 9.6 +- 0.4. The broad CIV-1549A line is asymmetric and significantly blue-shifted. The derived M_BH from the blueshift-corrected broad CIV line width agrees with the MgII result. From direct measurement using a well-sampled SED, the bolometric luminosity is 3.6 * 10^14 L_sun. The corresponding Eddington ratio for W2246-0526 is lambda_Edd = L_AGN / L_Edd = 2.8. This high Eddington ratio may reach the level where the luminosity is saturating due to photon trapping in the accretion flow, and be insensitive to the mass accretion rate. In this case, the M_BH growth rate in W2246-0526 would exceed the apparent accretion rate derived from the observed luminosity.