GMASS ultradeep spectroscopy of galaxies at z ~ 2 - VII. Star formation, extinction, and gas outflows from UV spectra

TL;DR

This study uses UV spectroscopy of z~2 galaxies to analyze star formation, dust extinction, and gas outflows, revealing correlations among these properties and galaxy mass, with outflows indicated by blueshifted absorption lines.

Contribution

It provides new insights into the relationships between star formation, dust, and gas outflows in high-redshift galaxies using deep UV spectra from GMASS.

Findings

Gas outflows have velocities around 100 km/s.

Positive correlation between SFR and stellar mass.

Interstellar absorption line strength correlates with SFR, mass, and color excess.

Abstract

We use rest-frame UV spectroscopy to investigate the properties related to large-scale gas outflows, and to the dust extinction and star-formation rates of a sample of z ~ 2 star-forming galaxies from the Galaxy Mass Assembly ultradeep Spectroscopic Survey (GMASS). Dust extinction is estimated from the rest-frame UV continuum slope and used to obtain dust-corrected star-formation rates for the galaxies of the sample. For the entire sample, a mean value of the continuum slope <\beta> = -1.11 \pm 0.44 (r.m.s.) was derived, while the average SFR was found to be <SFR> = 52 \pm 48 M_sun/yr (r.m.s.). A positive correlation between SFR and stellar mass was observed, in agreement with other works, the logarithmic slope of the relation being 1.10 \pm 0.10. Low-ionization absorption lines, associated with the interstellar medium, were found to be blueshifted, with respect to the rest frame of the system, which indicates that there is outflowing gas with typical velocities of the order of ~ 100 km/s. Finally, investigating correlations between galaxy UV spectral characteristics and galaxy general properties, we report a possible correlation between the equivalent width of the interstellar absorption lines and SFR, stellar mass, and colour excess similar to that seen to hold at different redshifts.