doi:10.1038/nindia.2012.97 Published online 30 June 2012
Researchers have provided new insights into the birth of a black hole by studying a distant source of gamma ray bursts (GRB) called GRB 090618, located around 6.5 Giga light years away.
They claim to have identified two episodes of bursts, one of them emanating from a massive star just before the gravitational collapse and the other just after. The study offers an unprecedented possibility of testing crucial aspects of theoretical models that predict gravitational collapse leading to formation of black holes.
To get an insight into the birth of a black hole, the researchers studied GRB 090618 using data and images from NASA's Fermi Gamma-Ray Satellite, the Indian payload RT-2 on board CORONAS PHOTON satellite, Swift satellite and Suzaku, a Japanese X-ray astronomy satellite and earth-bound observatories. They analyzed the emission from GRB 090618 using several spectral models.
The study found two episodes of GRBs. The first episode lasted 50 seconds and the second around 100 seconds. Unlike normal duration which lasts for 1-2 seconds, the first episode was very long. Using computer generated light curve and spectrum, the study claims that it is the signature of gravitational collapse paving the birth of a black hole. The second episode provided the signature of a usual GRB.
"We believe that this is the first case where the formation of black hole is actually observed before the GRB signature is seen. This is possible as the object is really nearby, only halfway to the edge of the Universe," says Sandip Chakrabarti, one of the researchers.
The authors of this work are from: S. N. Bose National Center for Basic Sciences and Indian Center for Space Physics, Kolkata, India; Dip. di Fisica and ICRA, Sapienza Università di Roma, Rome, and ICRANet, Piazza della Repubblica Pescara, Italy; and Universite de Nice Sophia Antipolis, Nice, France.