On the extreme positive star-formation feedback condition in SCUBA sources

TL;DR

This paper models the hydrodynamics of star feedback in young galaxies, revealing conditions under which star formation is self-sustaining and leads to rapid interstellar enrichment, especially in high star-forming SCUBA sources.

Contribution

It introduces a hydrodynamic framework that predicts three regimes of matter re-insertion in assembling galaxies, highlighting conditions for positive star-formation feedback in high-rate starburst galaxies.

Findings

Massive star-forming galaxies can sustain positive feedback regimes.

High star formation rates lead to minimal impact on the intergalactic medium.

Rapid interstellar matter enrichment occurs in these conditions.

Abstract

We present a detailed study of the hydrodynamics of the matter reinserted by massive stars via stellar winds and supernovae explosions in young assembling galaxies. We show that the interplay between the thermalization of the kinetic energy provided by massive stars, radiative cooling of the thermalized plasma and the gravitational pull of the host galaxy, lead to three different hydrodynamic regimes. These are: a) The quasi-adiabatic supergalactic winds. b) The bimodal flows, with mass accumulation in the central zones and gas expulsion from the outer zones of the assembling galaxy. c) The gravitationally bound regime, for which all of the gas returned by massive stars remains bound to the host galaxy and is likely to be reprocessed into futher generations of stars. Which of the three possible solutions takes place, depends on the mass of the star forming region its mechanical luminosity (or star formation rate) and its size. The model predicts that massive assembling galaxies with large star formation rates similar to those detected in SCUBA sources ($\sim 1000$ M$_\odot$ yr$^{-1}$) are likely to evolve in a positive star-formation feedback condition, either in the bimodal, or in the gravitationally bound regime. This implies that star formation in these sources may have little impact on the intergalactic medium and result instead into a fast interstellar matter enrichment, as observed in high redshift quasars.