XTE J1118480: A metal-rich black hole binary in the galactic halo

Jonay I. González Hernández, Rafael Rebolo, Garik Israelian, Emilios T. Harlaftis, Alexei V. Filippenko, Ryan Chornock

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We present medium-resolution optical spectra of the secondary star in the high Galactic latitude black hole X-ray binary XTE J1118480 and determine the abundance of Mg, Al, Ca, Fe, and Ni in its atmosphere. For all the elements investigated, we find supersolar abundances; thus, we reject the hypothesis that the black hole came from the direct collapse of an ancient massive halo star. The compact primary most likely formed in a supernova event of a massive star whose nucleosynthetic products polluted the secondary star. The observed element abundances and their ratios can be explained using a variety of supernova models with a wide range of metallicities. While an explosive origin in the Galactic halo or thick disk cannot be discarded, a metal-rich progenitor is clearly favored by the observed abundance pattern. This suggests that the black hole was produced in the Galactic thin disk with a violent natal kick, propelling the X-ray binary to its current location and orbit.

Original languageEnglish (US)
Pages (from-to)L49-L52
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Jun 10 2006
Externally publishedYes


  • Black hole physics
  • Stars: abundances
  • Stars: evolution
  • Stars: individual (XTE J1118480)
  • Supernovae: general
  • X-rays: binaries

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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