{
  "id": "1804.06116",
  "version": "v1",
  "published": "2018-04-17T09:04:29.000Z",
  "updated": "2018-04-17T09:04:29.000Z",
  "title": "Gravitational wave sources from inspiralling globular clusters in the Galactic Centre and similar environments",
  "authors": [
    "Manuel Arca Sedda",
    "Alessia Gualandris"
  ],
  "comment": "21 pages, 29 figures, 6 tables. Accepted for publication in MNRAS",
  "doi": "10.1093/mnras/sty922",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We model the inspiral of globular clusters (GCs) towards a galactic nucleus harboring a supermassive black hole (SMBH), a leading scenario for the formation of nuclear star clusters. We consider the case of GCs containing either an intermediate-mass black hole (IMBH) or a population of stellar mass black holes (BHs), and study the formation of gravitational wave (GW) sources. We perform direct summation $N$-body simulations of the infall of GCs with different orbital eccentricities in the live background of a galaxy with either a shallow or steep density profile. We find that the GC acts as an efficient carrier for the IMBH, facilitating the formation of a bound pair. The hardening and evolution of the binary depends sensitively on the galaxy's density profile. If the host galaxy has a shallow profile the hardening is too slow to allow for coalescence within a Hubble time, unless the initial cluster orbit is highly eccentric. If the galaxy hosts a nuclear star cluster, the hardening leads to coalescence by emission of GWs within $3-4$ Gyr. In this case, we find a IMBH-SMBH merger rate of $\\Gamma_{\\rm IMBH-SMBH} = 2.8\\times 10^{-3}$ yr$^{-1}$ Gpc$^{-3}$. If the GC hosts a population of stellar BHs, these are deposited close enough to the SMBH to form extreme-mass-ratio-inspirals with a merger rate of $\\Gamma_{\\rm EMRI} = 0.25$ yr$^{-1}$ Gpc$^{-3}$. Finally, the SMBH tidal field can boost the coalescence of stellar black hole binaries delivered from the infalling GCs. The merger rate for this merging channel is $\\Gamma_{\\rm BHB} = 0.4-4$ yr$^{-1}$ Gpc$^{-3}$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-04-17T09:04:29.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gravitational wave sources",
      "inspiralling globular clusters",
      "galactic centre",
      "similar environments",
      "black hole binaries"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 21,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}