Single star progenitors of long gamma-ray bursts - I. Model grids and redshift dependent GRB rate (original) (raw)

A&A 460, 199-208 (2006)

I. Model grids and redshift dependent GRB rate

1 Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ, Amsterdam, The Netherlands e-mail: scyoon@science.uva.nl
2 Astronomical Institute, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands e-mail: n.langer@astro.uu.nl
3 The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218, USA
4 Space Telescope Science Institute, 3700 San Martine Drive, Baltimore, MD 21218, USA e-mail: norman@stsci.edu

Received: 26 June 2006
Accepted: 24 August 2006

Abstract

We present grids of massive star evolution models at four different metallicities ( $Z=0.004, 0.002, 0.001, 0.00001$ ). The effects of rotation on the stellar structure and the transport of angular momentum and chemical elements through the Spruit-Tayler dynamo and rotationally induced instabilities are considered. After discussing uncertainties involved with the adopted physics, we elaborate the final fate of massive stars as a function of initial mass and spin rate, at each considered metallicity. In particular, we investigate for which initial conditions long gamma-ray bursts (GRBs) are expected to be produced in the frame of the collapsar model. Then, using an empirical spin distribution of young massive metal-poor stars and a specified metallicity-dependent history of star-formation, we compute the expected GRB rate as function of metallicity and redshift based on our stellar evolution models. The GRB production in our models is limited to metallicities of $Z \la 0.004$ , with the consequence that about 50% of all GRBs are predicted to be found at redshifts above $z = 4$ , with most supernovae occurring at redshifts below $z\simeq 2.2$ . The average GRB/SN ratio predicted by our model is about $1/200$ globally, and $1/1250$ at low redshift. Future strategies for testing the considered GRB progenitor scenario are briefly discussed.

Key words: stars: evolution / stars: rotation / supernovae: general / gamma rays: bursts