According to the Sky and Telescope blog, NASA’s Swift satellite captured a faint gamma-ray burst (GRB) last Thursday which has smashed the record for the earliest, most distant known object in the universe. Various ground-based telescopes following up on Swift’s initial detection of the GRB have measured redshifts of the object, varying from 7.6 to 8.2. Whatever the final determination is of how much this GRB’s afterglow has been redshifted by the expansion of the Universe, it will set a record. In September 2008, Swift captured GRB 080913, the most distant gamma-ray burst ever detected, with a redshift of 6.7. Astronomers using the Very Large Telescope in Chile have determined that this current GRB (090423) went off about 600 million years after the Big Bang.
A GRB comes from the cataclysmic explosion of a massive star, which could signal the birth of a black hole, a collision of two neutron stars or some other unknown phenomenon. These bursts occur approximately once per day and are brief, but intense, flashes of gamma radiation. They come from all different directions of the sky and last from a few milliseconds to a few hundred seconds.
Since the Swift satellite was launched in 2004, it has undoubtedly seen GRBs with even higher redshifts, but many bursts have afterglows so faint that astronomers are unable to determine their redshifts. The most distant galaxies with well-measured redshifts are in the 6’s.
NASA is supposed to issue a press release with more information later today, and we’ll provide an update at that time.