Galaxy formation and evolution

Abstract:

Abstract We investigate the relationship between disc winds, radio jets, accretion rates and black hole masses of a sample of ∼100k quasars at z ≈ 2. Combining spectra from the 17th data release of the Sloan Digital Sky Survey (SDSS) with radio fluxes from the 2nd data release of the Low Frequency ARray (LOFAR) Two-Meter Sky Survey (LoTSS), we statistically characterise a radio loud and radio quiet population using a two-component Gaussian Mixture model, and perform population matching in black hole mass and Eddington fraction. We determine how the fraction of radio loud sources changes across this parameter space, finding that jets are most efficiently produced in quasars with either a very massive central black hole (MBH > 109M⊙) or one that is rapidly accreting (λEdd > 0.3). We also show that there are differences in the blueshift of the $\textrm {C}\, \rm \small {IV}$ λ1549Å line and the equivalent width of the $\rm {He}\, \rm \small {II}$ λ1640Å line in radio loud and radio quiet quasars that persist even after accounting for differences in the mass and accretion rate of the central black hole. Generally, we find an anti-correlation between the inferred presence of disc winds and jets, which we suggest is mediated by differences in the quasars’ spectral energy distributions. The latter result is shown through the close coupling between tracers of wind kinematics and the ionising flux– which holds for both radio loud and radio quiet sources, despite differences between their emission line properties– and is hinted at by a different Baldwin effect in the two populations.

Abstract:

The James Webb Space Telescope is discovering increasing numbers of quiescent galaxies 1–2 billion years after the Big Bang, whose redshift, high mass and old stellar ages indicate that their formation and quenching were surprisingly rapid. This fast-paced evolution seems to require that feedback from active galactic nuclei be faster and/or more efficient than previously expected. We present deep Atacama Large Millimeter/submillimeter Array (ALMA) observations of cool molecular gas (the fuel for star formation) in a massive, fast-rotating, quiescent galaxy at z = 3.064, GS-10578. This galaxy hosts an active galactic nucleus, driving neutral-gas outflows with a mass-outflow rate of 60 ± 20 M⊙ yr−1, and it has a star-formation rate of <5.6 M⊙ yr−1. Our data reveal this system to be a distant gas-poor galaxy confirmed with direct CO observations (molecular-gas mass <109.1 M⊙; <0.8% of its stellar mass). Combining Atacama Large Millimeter/submillimeter Array and James Webb Space Telescope observations, we estimate the gas consumption history of this galaxy, showing that it evolved with net-zero gas inflow, that is, the gas consumption by star formation matches the amount of gas this galaxy is missing relative to star-forming galaxies. This could arise both from preventative feedback stopping further gas inflow, which would otherwise refuel star formation or, alternatively, from fine-tuned ejective feedback matching precisely gas inflows. These results show that galaxy quenching is a long-term effect rather than due to a rapid single quasar episode.