The Most Luminous Starbursts in the Universe

TL;DR

This study analyzes the luminosities and star formation rates of 243 starburst galaxies across redshifts 0 to 2.5 using PAH features from Spitzer data, revealing maximum luminosities and SFRs consistent with optical and radio studies.

Contribution

It provides empirical calibrations linking PAH luminosities to bolometric luminosities and star formation rates for luminous starbursts across a range of redshifts.

Findings

Luminosity scales as log[vLv(7.7um)] = 44.63 + 2.48 log(1+z).

Maximum star formation rate reaches about 3400 solar masses per year at z=2.5.

Luminosity evolution exponent aligns with optical and radio studies.

Abstract

A summary of starburst luminosities based on PAH features is given for 243 starburst galaxies with 0 < z < 2.5, observed with the Spitzer Infrared Spectrograph. Luminosity vLv(7.7um) for the peak luminosity of the 7.7um PAH emission feature is found to scale as log[vLv(7.7um)] = 44.63(+-0.09) + 2.48(+-0.28)log(1+z) for the most luminous starbursts observed. Empirical calibrations of vLv(7.7um) are used to determine bolometric luminosity Lir and the star formation rate (SFR) for these starbursts. The most luminous starbursts found in this sample have log Lir = 45.4(+-0.3) + 2.5(+-0.3)log(1+z), in ergs per s, and the maximum star formation rates for starbursts in units of solar masses per yr are log(SFR) = 2.1(+-0.3) + 2.5(+-0.3)log(1+z), up to z = 2.5. The exponent for pure luminosity evolution agrees with optical and radio studies of starbursts but is flatter than previous results based in infrared source counts. The maximum star formation rates are similar to the maxima determined for submillimeter galaxies; the most luminous individual starburst included within the sample has log Lir = 46.9, which gives a SFR = 3400 solar masses per yr.