GRB in z=6.7

Gamma ray bursts (GRB)/are the most luminous electromagnetic events occurring in the universe since the Big Bang. They are flashes of gamma rays emanating from seemingly random places in deep space at random times/, are lately in focus of great attention.The speculation that maybe they would be possible standard candles make their importance more.

If there are standard candles then we can track the expansion history of universe in higher redshifts,cause they founded farther than supernovas.The farthest Gamma ray burst is founded in z=6.7 the report of this GCN is reported in work of Fynbo et al.This is the report.

"

TITLE: GCN CIRCULAR NUMBER: 8225

SUBJECT: GRB 080913:

VLT/FORS spectrum

DATE: 08/09/13 17:28:26 GMT

J.P.U. Fynbo (DARK/NBI), J. Greiner, T. Kruehler (both MPE),A. Rossi (Tautenburg Obs), P. Vreeswijk, D. Malesani (both DARK/NBI)report on behalf of a larger collaboration

Based on the rapid determination of an "i-band" drop out we triggered VLT/ToO observations (program-ID 081.A-0135; PI Greiner) and obtained spectroscopy with FORS2+Gris600z of the afterglow of GRB080913(Schady et al. 2008, GCN #8217; Stamatikos et al. 2008, GCN #8222*.

Observations started at 8:30, about 100 min after the GRB, and continueduntil morning twilight. We detect a red continuum that disappears bluewards of a break around 9400 AA. Interpreting this break as the onset of the Lyman-alpha forest we infer a redshift of about z=6.7 consistent with the photometric redshift determined by GROND (Greiner et al., GCN #8223)."

*http://gcn.gsfc.nasa.gov/gcn3_archive.html#tc1

But the physics of GRB is undiscovered yet.,further investigations may assure us about their physics.

footnote:

Thanks to Amir a Gamma ray burst investigator in Michigan tech physics department.