Consequences of a low-mass, high-pressure, star formation mode in early galaxies

TL;DR

This paper explores a low-mass, high-pressure star formation mode in early galaxies, linking high-redshift galaxy evolution, black hole growth, and the presence of low-mass stars in nearby ellipticals.

Contribution

It revives the idea that high thermal pressure in cooling flows can induce low-mass star formation, connecting early galaxy conditions with present-day observations.

Findings

Hidden cooling flows deposit cold gas in galaxy centers

A bottom-heavy initial mass function is common in inner regions

Low-mass star formation may have occurred in early galaxies

Abstract

High resolution X-ray spectra reveal hidden cooling flows depositing cold gas at the centres of massive nearby early-type galaxies with little sign of normal star formation. Optical observations are revealing that a bottom-heavy Initial Mass Function is common within the inner kpc of similar galaxies. We revive the possibility that a low-mass star formation mode is operating due to the high thermal pressure in the cooling flow, thus explaining the accumulation of low-mass stars. We further explore whether such a mode operated in early, high-redshift galaxies and has sporadically continued to the present day. The idea links observed distant galaxies with black holes which are ultramassive for their stellar mass, nearby red nuggets and massive early-type galaxies. Nearby elliptical galaxies may be red but they are not dead.