Bibcode
DOI
González Hernández, Jonay I.; Rebolo, Rafael; Israelian, Garik; Filippenko, Alexei V.; Chornock, Ryan; Tominaga, Nozomu; Umeda, Hideyuki; Nomoto, Ken'ichi
Bibliographical reference
The Astrophysical Journal, Volume 679, Issue 1, pp. 732-745.
Advertised on:
5
2008
Journal
Citations
40
Refereed citations
37
Description
Following recent abundance measurements of Mg, Al, Ca, Fe, and Ni in the
black hole X-ray binary XTE J1118+480 using medium-resolution Keck II
ESI spectra of the secondary star, we perform a detailed abundance
analysis including the abundances of Si and Ti. These element
abundances, which are higher than solar, indicate that the black hole in
this system formed in a supernova event, whose nucleosynthetic products
could pollute the atmosphere of the secondary star, providing clues to
the possible formation region of the system, either Galactic halo, thick
disk, or thin disk. We explore a grid of explosion models with different
He core masses, metallicities, and geometries. Metal-poor models
associated with a formation scenario in the Galactic halo provide
unacceptable fits to the observed abundances, allowing us to reject a
halo origin for this X-ray binary. The thick-disk scenario produces
better fits, although they require substantial fallback and very
efficient mixing processes between the inner layers of the explosion and
the ejecta, making an origin in the thick disk quite unlikely. The best
agreement between model predictions and the observed abundances is
obtained for metal-rich progenitor models. In particular,
non-spherically symmetric models are able to explain, without strong
assumptions of extensive fallback and mixing, the observed abundances.
Moreover, asymmetric mass ejection in a supernova explosion could
account for the required impulse necessary to launch the system from its
formation region in the Galactic thin disk to its current halo orbit.