Nancy A. Levenson
Science Highlights
From extremely fast-turnaround GRB observations to the first published
science paper from GeMS/GSAOI data, science results from Gemini during
the past quarter demonstrate remarkable new technical capabilities and
our expanding scientific discovery-space.
Intergalactic and Interstellar Medium Studies with Gamma-Ray Bursts
The high-redshift gamma-ray burst denoted GRB 130606A rapidly demonstrated its utility
as a probe of the intergalactic medium — both along the line-of-sight to Earth and through
the interstellar medium of its host galaxy. On June 6th of this year, Ryan Chornock (Harvard
University) and colleagues used the Gemini Multi-object Spectrograph at Gemini North to
obtain sensitive observations of the GRB’s afterglow within 13 hours of when NASA’s Swift
satellite first detected the burst. They
used the data to measure reionization in
the early universe and properties of the
host galaxy (Figure 1).
Figure 1.
This artistic rendering
illustrates how the light
from GRB 130606A
serves as a beacon
through the interstellar
gas of the host galaxy of
the burst source. It also
reveals the ionization
state of the medium
between galaxies along
the line of sight.
At redshift z = 5.91, GRB 130606A remains one of just a handful of spectroscopically confirmed GRBs at z 6.
Quasars have been used to probe the intergalactic medium (IGM) at this epoch,
when the universe was only one billion
years old. This work is the first to provide
a similarly high-quality GRB spectrum
for analysis.
An advantage of pursuing this work with
GRBs is that there is no expected bias toward highly ionized areas, as may be the
case with quasars. The net results along
this single sightline are similar to those
obtained based on quasar observations,
October2013
GeminiFocus 11