NASAs Swift Satellite has gathered some landmark observations over a period of four months and these observations have challenged the astronomer’s view point of gamma-ray bursts.
Gamma Ray bursts or simply GRBs are the most extreme events in the universe.
GRB corresponds to the explosive death of very massive stars releasing huge amounts of energy and matter. Some explosions are so huge that they eject jets that can release as much matter and energy in seconds that our sun will release in its entire life.
These jets slam into interstellar gas resulting in an intense afterglow that can radiate brightly in X-Rays for several weeks.
Swift has also monitored similar afterglow that remained visible for more than 125 days.
Swift’s BRT detected the GRB in constellation Pictor on July 29, 2006. The XRT picked up GRB 060729 124 seconds later. Normally these blasts show for about a week and fades to near invisibility after that.
This means that such a large afterglow requires a larger energy injection than what we normally see in bursts and also requires continuous power from the core.
According to the astronomers the reason for such prolonged afterglow can be the fact the GRB’s central engine was a magnetar, that is a neutron with a ultra-powerful magnetic field.
The magnetic field acts as a brake to slow down the spin of the star. This slow down can be converted into magnetic energy that is continuously injected into the initial blast wave that triggered the GRB.
A burst observed on January 10, 2007 has also demonstrated that some magnetars can also power some GRBs.
Until now every astronomer was of the belief that GRBs are black holes in the making but after this research they are now thinking of some more possibilities.
Another surprising result from GRB 060729 is that the afterglow never showed any sharp decrease in brightness over the 125-day period. For this the astronomers state that the GRBs jet must have been at an angle of at least 28-degrees wide, in contrast other GRBs jets have an angle of about 5 degrees.
Via: physorg
