Extreme Primordial Star Formation Enabled by High Redshift Quasars

TL;DR

High redshift quasars can heat the surrounding primordial gas, delaying star formation until massive halos form, which may lead to early Population III starbursts and direct collapse black holes, detectable by JWST.

Contribution

This study models the thermal and chemical evolution of primordial gas near high-z quasars, highlighting conditions for Pop III star formation and DCBH creation.

Findings

Quasars can suppress star formation in low-mass halos.

High Lyman-Werner flux near quasars may trigger direct collapse black holes.

JWST observations could detect early Pop III stars and DCBHs.

Abstract

High redshift quasars emit copious X-ray photons which heat the intergalactic medium to temperatures up to $\sim$ 10$^6$ K. At such high temperatures the primordial gas will not form stars until it is assembled into dark matter haloes with masses of up to $\sim$ 10$^{11}$ M$_{\odot}$, at which point the hot gas collapses and cools under the influence of gravity. Once this occurs, there is a massive reservoir of primordial gas from which stars can form, potentially setting the stage for the brightest Population (Pop) III starbursts in the early Universe. Supporting this scenario, recent observations of quasars at z $\sim$ 6 have revealed a lack of accompanying Lyman $\alpha$ emitting galaxies, consistent with suppression of primordial star formation in haloes with masses below $\sim$ 10$^{10}$ M$_{\odot}$. Here we model the chemical and thermal evolution of the primordial gas as it collapses into such a massive halo irradiated by a nearby quasar in the run-up to a massive Pop III starburst. We find that within $\sim$ 100 kpc of the highest redshift quasars discovered to date the Lyman-Werner flux produced in the quasar host galaxy may be high enough to stimulate the formation of a direct collapse black hole (DCBH). A survey with single pointings of the NIRCam instrument at individual known high-z quasars may be a promising strategy for finding Pop III stars and DCBHs with the James Webb Space Telescope.