Gas outflows from the z= 7.54 quasar : predictions from the BlueTides Simulation

TL;DR

This study uses the BlueTides simulation to predict and analyze gas outflows from a high-redshift quasar at z=7.54, revealing details about outflow mass, velocity, and composition, consistent with observational data.

Contribution

It introduces a novel method to identify and trace gas outflows in a large cosmological simulation at high redshift, providing detailed predictions for quasar-driven outflows.

Findings

Outflow gas mass is about 3.6×10^9 M_sun, 6% of halo gas.

Outflow velocities reach thousands of km/s, with molecular component averaging 1300 km/s.

Outflow rate is approximately 200-300 M_sun/yr, mainly hot and low-density gas.

Abstract

Many theoretical models predict that quasar driven outflows account for the observed quenching of star formation in massive galaxies. There is growing observational evidence for quasar-launched massive outflows at z>6, while the details of outflow-host galaxy interaction remain obscure. In this paper, we study the feedback around the highest redshift quasar in the BlueTides simulation, the largest volume cosmological hydrodynamic simulation so far carried out. We present predictions for gas outflows around the brightest $z = 7.54$ quasar which hosts the most massive black hole in the simulation volume, which has grown to black hole mass $6.7\times 10^{8}{\rm M}_\odot$ consistent with the current record holder for high-z quasars. We introduce a method to identify and trace the gas outflowing from the halo. We find that the total mass of the outflow gas is about $3.6\times 10^{9}{\rm M}_\odot$, constituting 6\% of the total gas in the halo. The outflow gas contains a cold, dense molecular component with mass about $2.6\times 10^{8}{\rm M}_\odot$, that originates from the inner region of the halo, within a few kpc of the central black hole. The velocities of the outflow gas reach thousands of km/s, within which the molecular component has mass averaged outward radial velocity of $1300$ km/s, consistent with observations. The averaged outflow rate is about $200-300 {\rm M}_\odot/yr$, with the outflowing gas mainly in a hotter ($T \sim 10^7$ K) and lower density state than the average of the host halo gas.