Star formation in thin disks of spiral galaxies seen face-on

TL;DR

This study estimates star formation rates in 181 face-on spiral galaxies using GALEX FUV data, revealing trends in specific star formation rates across galaxy types and implications for their past star formation activity.

Contribution

It provides new measurements of SFR and sSFR for face-on spiral galaxies and analyzes their variation and evolution over cosmic time.

Findings

sSFR decreases from Sc to Sd types

Small cosmic variation in sSFR (~0.16 dex)

Past SFR was 2-3 times higher than current in these galaxies

Abstract

Estimates of the integrated (SFR) and specific (sSFR) rates of star formation are given for 181 galaxies of later Sc, Scd, and Sd types seen almost face-on. Their SFRs were determined from FUV fluxes in the GALEX survey. The median values of the sSFR are: -10.66 dex for Sc, -10.44 dex for Scd, and -10.40 dex for Sd types in units of yr-1. The average value of the sSFR for these galaxies falls off smoothly from lowmass to giant disks. After accounting for photometric errors, the specific star formation rate has a small cosmic variation of 0.16 dex. In order to reproduce the observed stellar mass on a cosmic time of 13.8 Gyr, the galaxies without bulges viewed face-on must have had an SFR two-three times higher in the past than observed now.