The Cosmic Evolution of Gamma-Ray Burst Host Galaxies
  Due to their extreme luminosities, gamma-ray bursts (GRBs) can be detected in
hostile regions of galaxies, nearby and at very high redshift, making them
important cosmological probes. The investigation of galaxies hosting
long-duration GRBs (whose progenitor is a massive star) demonstrated their
connection to star formation. Still, the link to the total galaxy population is
controversial, mainly because of the small-number statistics: ~ 1,100 are the
GRBs detected so far, ~ 280 those with measured redshift, and ~ 70 the hosts
studied in detail. These are typically low-redshift (z < 1.5), low luminosity,
metal poor, and star-forming galaxes. On the other hand, at 1.5< z <4, massive,
metal rich and dusty, interacting galaxies are not uncommon. The most distant
population (z > 4) is poorly explored, but the deep limits reached point
towards very small and star-forming objects, similar to the low-z population.
This `back to the future' behavior is a natural consequence of the connection
of long GRBs to star formation in young regions of the universe.
