{
  "id": "2011.08519",
  "version": "v1",
  "published": "2020-11-17T09:14:19.000Z",
  "updated": "2020-11-17T09:14:19.000Z",
  "title": "The dispersion measure and scattering of FRBs: Contributions from the intergalactic medium, foreground halos, and hosts",
  "authors": [
    "Weishan Zhu",
    "Long-Long Feng"
  ],
  "comment": "21 pages, 13 figures. Accepted for publication in ApJ",
  "categories": [
    "astro-ph.HE",
    "astro-ph.CO",
    "astro-ph.GA"
  ],
  "abstract": "We investigate the dispersion measure(DM) and scattering of FRBs by the intergalactic-medium(IGM), foreground and host halos, using cosmological hydrodynamical simulation. We find that the median DM caused by foreground halos is around 30\\% of that caused by the IGM, but has a much larger variance. The DM induced by hosts deviates from a log-normal distribution, but exhibits an extended distribution in the range of $1-3000 \\ {\\rm{pc\\, cm^{-3}}}$ with a median value $\\sim 100 \\ {\\rm{pc\\, cm^{-3}}}$. Then we produce mock FRB sources, assuming a uniform distribution in the range $z\\sim 0-0.82$, to consider the propagation effect of IGM, foreground and host halos on FRB signals simultaneously. The DM distribution of mock sources agrees well with the observation. The fitted DM-redshift relation of the mock sources can provide a rough estimation of the redshifts of observed events with errors $\\delta z \\lesssim 0.15$. The distribution of mock sources in the DM-scattering time($\\tau$) space can also match the observation, assuming a Kolmogorov turbulence model with the inner and outer scale is 1000 km to 1 AU, and 0.2-10 pc respectively. Finally, we estimate the relative importance of these medium on DM and $\\tau$ in our models. The IGM and host halos are the primary and secondary sources to the extragalactic DM, $\\rm{DM_{exg}}$. Meanwhile, the contribution from foreground halos increases as $\\rm{DM_{exg}}$ increases. The host and foreground halos may be the most important medium for scattering. Statistically, the latter may dominate the scattering of events with $\\rm{DM_{exg}} \\gtrsim 200 \\ {\\rm{pc\\, cm^{-3}}}$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-11-17T09:14:19.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "dispersion measure",
      "intergalactic medium",
      "host halos",
      "mock sources",
      "scattering"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 21,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}