Supernovae and Gamma-Ray Bursts
SNe and GRB Evolution in the Winds of Massive Stars [Oral Contribution]
Dwarkadas, Vikram
Presented at the KITP Conference: Supernova and Gamma-Ray Burst Remnants, Feb 7, 2006, Kavli Institute for Theoretical Physics, University of California, Santa Barbara
02/2006
Abstract
I discuss the formation and growth of the medium around massivestars, especially Wolf-Rayet stars, and its impact on the evolution of theresultant shock wave when the star ends its life as a SN. The circumstellarmedium is formed by mass-loss from the star during its various evolutionarystages. Using analytical calculations and numerical simulations, I studythe evolution of this medium, multidimensional effects such ashydrodynamical instabilities, and the onset of turbulence. When the starexplodes as a SN, the resulting shock wave will interact with thismedium. I further explore the impact of the ambient medium on the expansionof the shock wave and the evolution of the remnant. Similarly, the impacton GRB afterglows and absorption spectra of GRBs is considered.
Time-resolved spectroscopy of GRB 021004 reveals a clumpy extended wind
Lazzati, Davide; Perna, Rosalba; Flasher, Joseph; Dwarkadas, Vikram V.; Fiore, Fabrizio
Monthly Notices of the Royal Astronomical Society, Volume 372, Issue 4, pp. 1791-1798. 11/2006
Abstract
A high-resolution spectroscopy of GRB 021004 revealed a wealth of absorption lines from several intermediate-ionization species. The velocity structure of the absorber is complex and material with velocity up to >~3000kms-1 is observed. Since only the blueshifted component is observed, the absorber is very likely to be material closely surrounding the gamma-ray burst. We use a time-dependent photoionization code to track the abundance of the ions over time. Thanks to the presence of absorption from intermediate-ionization states at long times, we can estimate the location and mass of the components of the absorber. We interpret those constraints within the hypernova scenario showing that the mass-loss rate of the progenitor must have been ~10-4Msolaryr-1, suggestive of a very massive star. In addition, the wind termination shock must lie at a distance of at least 100 pc, implying a low-density environment. The velocity structure of the absorber also requires clumping of the wind at those large distances.
Winds From Massive Stars and Implications for Supernovae and Gamma-Ray Bursts
Dwarkadas, Vikram V.
THE MULTICOLORED LANDSCAPE OF COMPACT OBJECTS AND THEIR EXPLOSIVE ORIGINS. AIP Conference Proceedings, Volume 924, pp. 249-254 (2007)
08/2007
Abstract
We review the effects of winds from massive O and B stars on the surrounding medium over the various stages of stellar evolution. Furthermore we discuss some of the implications for SNe and GRB evolution within this wind-blown medium.