1000 Bursts with Fermi!

October 01, 2012

On 21 September, the gamma-ray burst monitor (GBM) instrument onboard the Fermi satellite detected its 1000th cosmic explosion. It lasted for around 3 seconds, and consisted of a single large pulse of gamma-rays. Automatically detected by the GBM, an alert was sent to the ground that was then relayed to a worldwide team of astronomers just a few seconds later.

<p>Sky distribution of the 1000 GBM-triggered GRBs in celestial coordinates. Crosses indicate long GRBs (duration &gt; 2 s); asterisks indicate short GRBs.</p> Zoom Image

Sky distribution of the 1000 GBM-triggered GRBs in celestial coordinates. Crosses indicate long GRBs (duration > 2 s); asterisks indicate short GRBs.

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Gamma-ray bursts (GRBs) are the most violent and brightest events known in the universe and allow the astronomers to see farther than any other class of objects. The gamma-ray burst monitor (GBM) was specifically designed by scientists at the MPE and other institutes to study transient sources and provides unprecedented energy coverage in X-rays and gamma rays. This allows completely new studies to better understand the emission process of the gamma-ray radiation. Redshifts have been measured for a good fraction of these events. This makes it possible to study the rest-frame properties of GRBs for the first time. With highest-energy photons detected even at large redshift, the GRBs can also be used to probe the extragalactic background light, the glow from the global star formation history over cosmic time.

Originally, predictions indicated that it would take about 5 years before reaching 1000 burst detections. However, due to excellent performance of the detectors, built in Germany, and sophisticated search routines implemented by the team of scientists who developed the GBM, the rate of GRB detections has been significantly higher. And each new detection helps the astronomers to better understand these interesting events.