Reconsidering the origin of the X-ray emission lines in GRB 011211

¹ INAF–Osserv. Astron. di Brera, via Bianchi 46, 23807 Merate, Italy
² Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK

Corresponding author: F. Tavecchio, tavecchio@merate.mi.astro.it

Received: 14 May 2003
Accepted: 29 September 2003

Abstract

We reanalyze the XMM–Newton data of GRB 011211 showing that the spectral features, interpreted by Reeves et al. ([CITE], [CITE]) as due to thermal emission from a collisionally ionized plasma, can be also reproduced by a reflection model (with ionization parameter ). We discuss the implications of this interpretation, estimating the total mass required in the simplified case of a funnel geometry. We conclude that a moderate clumping of the reprocessing material (corresponding to a filling factor of the order of ) is required. Finally we show that, if this interpretation is correct, a bright quasi–thermal component is expected in the optical–UV band (containing about of the luminosity of the illuminating continuum), whose presence can be used to test the reflection model.