The most luminous starbursts in the universe

A summary of starburst luminosities based on polycyclic aromatic hydrocarbon (PAH) features is given for 243 starburst galaxies with 0 < z < 2.5, observed with the Spitzer Infrared Spectrograph. Luminosity nu L-nu(7.7 mu m) for the peak luminosity of the 7.7 mu m PAH emission feature is found to scale as log [nu L-nu (7.7 mu m)] = 44.63(+/- 0.09) + 2.48(+/- 0.28) log (1 + z) for the most luminous starbursts observed. Empirical calibrations of nu L-nu (7.7 mu m) are used to determine bolometric luminosity L-IR 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 s(-1), and the maximum star formation rates for starbursts in units of M-circle dot yr(-1) 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 L-IR = 46: 9, which gives an SFR 3.4 x 10(3) M-circle dot yr(-1).