{
  "id": "1510.02093",
  "version": "v1",
  "published": "2015-10-07T20:07:05.000Z",
  "updated": "2015-10-07T20:07:05.000Z",
  "title": "Formation of Black Hole Low-Mass X-ray Binaries in Hierarchical Triple Systems",
  "authors": [
    "Smadar Naoz",
    "Tassos Fragos",
    "Aaron Geller",
    "Alexander P. Stephan",
    "Frederic A. Rasio"
  ],
  "comment": "submitted, 4 figures",
  "categories": [
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "The formation of Black Hole (BH) Low-Mass X-ray Binaries (LMXB) poses a theoretical challenge, as low-mass companions are not expected to survive the common-envelope scenario with the BH progenitor. Here we propose a formation mechanism that skips the common-envelope scenario and relies on triple-body dynamics. We study the evolution of hierarchical triples, following the secular dynamical evolution up to the octupole-level of approximation, including general relativity, tidal effects and post-main-sequence evolution, such as mass loss, changes to stellar radii and supernovae. During the dynamical evolution of the triple system, the \"eccentric Kozai-Lidov\" mechanism can cause large eccentricity excitations in the LMXB progenitor, resulting in three main BH-LMXB formation channels. Here we define BH-LMXB candidates as systems where the inner BH companion star crosses its Roche limit. In the \"eccentric\" channel (~ 81% of the LMXBs in our simulations), the donor star crosses its Roche limit during an extreme eccentricity excitation, while still on a wide orbit. Second, we find a \"giant\" LMXB channel (~ 11%), where a system undergoes only moderate eccentricity excitations, but the donor star fills its Roche lobe after evolving toward the giant branch. Third, we identify a \"classical\" channel (~8%), where tidal forces and magnetic braking shrink and circularize the orbit to short periods, triggering mass transfer. Finally, for the giant channel, we predict an eccentric ($\\sim 0.3-0.6$), preferably inclined (~40, ~140 degreed) tertiary, typically on a wide enough orbit (~10^4AU), to potentially become unbound later in the triple evolution.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-10-07T20:07:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "black hole low-mass x-ray binaries",
      "hierarchical triple systems",
      "bh companion star crosses",
      "eccentricity excitation"
    ],
    "publication": {
      "doi": "10.3847/2041-8205/822/2/L24"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1396676
    }
  }
}