The definitive version is available at www.blackwell-synergy.com. Copyright Blackwell Publishing DOI : 10.1111/j.1365-2966.2005.09938.xPeer reviewe

Daigne, F.

Eldridge, J.J.

Genet, F.

Mochkovitch, R.

Monthly Notices of the Royal Astronomical Society

English

arXiv

J. J. Eldridge

F. Genet

F. Daigne

R. Mochkovitch

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The circumstellar environment of Wolf-Rayet stars and gamma-ray burst afterglows

University of Hertfordshire Research Archive

ApJ, 584, 47 Bloom et al., 2005, astro-ph/0505480 Bo¨hm-Vitense E,

ApJ, 595, 935 The circumstellar environment of Wolf-Rayet stars & Gamma-ray burst afterglows. 35 Nugis T., Lamers H.J.G.L.M.,

International audienceWe study the evolution of the circumstellar medium of massive stars. We pay particular attention to Wolf-Rayet stars that are thought to be the progenitors of some long gamma-ray bursts (GRBs). We detail the mass-loss rates we use in our stellar evolution models and how we estimate the stellar wind speeds during different phases. With these details we simulate the interactions between the wind and the interstellar medium to predict the circumstellar environment around the stars at the time of core-collapse. We then investigate how the structure of the environment might affect the GRB afterglow. We find that when the afterglow jet encounters the free-wind/stalled-wind interface, rebrightening occurs and a bump is seen in the afterglow light curve. However, our predicted positions of this interface are too distant from the site of the GRB to reach while the afterglow remains observable. The values of the final wind density, A*, from our stellar models are of the same order (* values below 0.5 inferred from afterglow observations. For these cases, we suggest that the progenitors could have been a WO-type Wolf-Rayet (WR) star or a very low-metallicity star. Finally, we turn our attention to the matter of stellar wind material producing absorption lines in the afterglow spectra. We discuss the observational signatures of two WR stellar types, WC and WO, in the afterglow light curve and spectra. We also indicate how it may be possible to constrain the initial mass and metallicity of a GRB progenitor by using the inferred wind density and wind velocity

Eldridge, J. J.

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http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.256.4979

The circumstellar environment of Wolf-Rayet stars and gamma-ray burst afterglows

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University of Hertfordshire Research Archive

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