Extreme Values of Black Hole to Stellar Mass Ratio for High-Redshift Galaxies

TL;DR

This paper uses extreme-value statistics on JWST data to predict the black hole to stellar mass ratio in high-redshift galaxies, finding values consistent with observations.

Contribution

It introduces a novel application of extreme-value statistics to predict black hole to stellar mass ratios at high redshifts.

Findings

Predicted ratio of ~0.24 across redshifts 3.5 to 8.5.

Median ratio varies between 0.18 and 0.35.

Predictions align with observed high-redshift galaxy data.

Abstract

With recent data from the \emph{James Webb Space Telescope} (JWST), it is possible to calculate the mass of the supermassive black holes at the centre of galaxies, and the stellar mass of the host galaxies at $z \gtrsim 5$. In this work, we apply the method of extreme-value statistics to calculate the distributions of extreme black hole and stellar mass for the redshift range $3.5 \lesssim z \lesssim 8.5$. We sample these distributions to obtain a prediction for the black hole to stellar mass ratio of $\sim0.24$ over this redshift range, with the median in each bin varying in the range $0.18-0.35$. Our predictions are consistent with the highest observed values of the ratio from JWST observations of high-redshift galaxies.