EDP Sciences
Free access
Volume 387, Number 1, May III 2002
Page(s) 215 - 221
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20020359

A&A 387, 215-221 (2002)
DOI: 10.1051/0004-6361:20020359

Evidence for a relativistic iron line in GRS 1915+105

A. Martocchia1, G. Matt1, V. Karas2, T. Belloni3 and M. Feroci4

1  Dipartimento di Fisica, Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
2  Astronomical Institute, Charles University Prague, Faculty of Mathematics and Physics, V Holesovickách 2, CZ-180 00 Praha, The Czech Republic
3  Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy
4  IAS/CNR, Area di Ricerca di Tor Vergata, Via Fosso del Cavaliere 100, 00133 Roma, Italy

(Received 6 November 2001 / Accepted 5 March 2002)

We report on the discovery of a relativistic iron K $\alpha$ fluorescent emission line in the BeppoSAX spectrum of the microquasar GRS 1915+105, taken on April 19, 1998, when the line was unusually intense. The feature is broad and skewed, clearly indicating emission from the innermost regions of the accretion disc. The inner emitting orbit is larger than the innermost stable orbit, even in Schwarzschild metric: thus, a non-zero BH spin is not required by these data.

Key words: black hole physics -- relativity -- line: formation -- line: profiles -- X-rays: individuals: GRS 1915+105

Offprint request: A. Martocchia, martocchia@fis.uniroma3.it

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