This week’s paper will be Relativistic shock breakouts – a variety of gamma-ray flares: from low luminosity gamma-ray bursts to type Ia supernovae by Nakar and Sari, June 13 2011 (arXiv:1106.2556v1).
The meeting will take place at 19:10 UT, 7th July 2011.
When a stellar core collapses it generates a shock wave that travels through the outer layers of the star. The moving shock wave heats material in front of it to thousands of degrees. For a brief moment, the star shifts from red-hot to white-hot until it shines mostly in ultraviolet and x-ray light. This stage is known as the shock breakout and is the first observable moment of a stellar explosion.
Shock breakouts at Newtonian velocities have been extensively explored. However, the breakout signature for explosions that result in mildly or ultra relativistic breakouts is unknown. This paper presents calculations for what this signature would look like.
The authors apply their models to a variety of explosions such as Type Ia supernovae and accretion induced collapse (AIC) to a neutron star. The authors conclude that these events should produce detectable gamma-ray signals, some of which we may already have the data for.
“Relativistic shock breakout is a generic process for the production of gamma-ray ﬂares, which opens a new window for the study and detection of a variety of stellar explosions.”
The paper was suggested by Derek Fox, who is a research astronomer at Penn State University. He writes:
This work provides a new theoretical treatment of relativistic shock breakout and goes on to apply the model to several classes of observed phenomena, reproducing their properties quantitatively and thus resolving some long-standing mysteries of gamma- and x-ray transients. Further, on the basis of their model the authors predict entirely new classes of gamma-ray transient that may be observable to current or next-generation missions.
In short, it’s quite the hearty meal of transient astrophysics, and I recommend it highly. I think, moreover, that one can glean a great deal from a fairly quick reading (abstract, discussion, and applications), hence it is an appropriate paper for this forum.