GRB 050509b
Encyclopedia
GRB 050509B was a gamma ray burst
(GRB) observed by the NASA Swift satellite
on May 9, 2005. It was the first short duration GRB for which an accurate positional measurement was made, accurate enough to locate it near to an elliptical galaxy
lying at a redshift
of 0.225.
The significance of this finding is that it lends support to the theory that short bursts are formed during the catastrophic merger of two neutron star
s, or a neutron star and a black hole
. The orbital decay
(via gravitational radiation) of stellar binaries consisting of these exotic compact objects is believed to take hundreds of millions of years, hence gamma ray bursts produced this way would be expected to be located in old (misleadingly called "early type") galaxies. In contrast, long-duration gamma ray bursts, which are believed to result from the collapse of a single massive star, are expected to be located preferentially in young galaxies.
Gamma ray burst
Gamma-ray bursts are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the most luminous electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several minutes, although a typical...
(GRB) observed by the NASA Swift satellite
Swift Gamma-Ray Burst Mission
The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on 20 November 2004, 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international...
on May 9, 2005. It was the first short duration GRB for which an accurate positional measurement was made, accurate enough to locate it near to an elliptical galaxy
Elliptical galaxy
An elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile. They range in shape from nearly spherical to highly flat and in size from hundreds of millions to over one trillion stars...
lying at a redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
of 0.225.
The significance of this finding is that it lends support to the theory that short bursts are formed during the catastrophic merger of two neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
s, or a neutron star and a black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...
. The orbital decay
Orbital decay
Orbital decay is the process of prolonged reduction in the altitude of a satellite's orbit.This can be due to drag produced by an atmosphere due to frequent collisions between the satellite and surrounding air molecules. The drag experienced by the object is larger in the case of increased solar...
(via gravitational radiation) of stellar binaries consisting of these exotic compact objects is believed to take hundreds of millions of years, hence gamma ray bursts produced this way would be expected to be located in old (misleadingly called "early type") galaxies. In contrast, long-duration gamma ray bursts, which are believed to result from the collapse of a single massive star, are expected to be located preferentially in young galaxies.