HIGH-REDSHIFT SUPERNOVAE AND THE METAL-POOR HALO STARS - SIGNATURES OF THE FIRST GENERATION OF GALAXIES

Recent evidence on the metal content of the high-redshift Ly alpha for est seen in quasar spectra suggests that an early generation of galaxi es enriched the intergalactic medium (IGM) at z greater than or simila r to 5. We calculate the number of supernovae that need to have taken place to produce the observed metallicity. The progenitor stars of the supernovae should have emitted similar to 20 ionizing photons for eac h baryon in the universe, i.e., more than enough to ionize the IGM. We calculate that the rate of these supernovae is such that about one of them should be observable at any time per square arcminute. Their flu xes are, of course, extremely faint: at z = 5, the peak magnitude shou ld be K = 27 with a duration of similar to 1 yr. However, these supern ovae should still be the brightest objects in the universe beyond some redshift, because the earliest galaxies should form before quasars an d they should have very low mass, so their luminosities should be much lower than that of a supernova. We also show that, under the assumpti on of a standard initial mass function, a significant fraction of the stars in the Galactic halo should have formed in the early galaxies th at reionized and enriched the IGM, and which later must have merged wi th our Galaxy. These stars should have a more extended radial distribu tion than the observed halo stars.