{
  "id": "2109.06632",
  "version": "v1",
  "published": "2021-09-09T10:55:51.000Z",
  "updated": "2021-09-09T10:55:51.000Z",
  "title": "Probing the physical properties of the intergalactic medium using blazars",
  "authors": [
    "Tony Dalton",
    "Simon L. Morris",
    "Michele Fumagalli",
    "Efrain Gatuzz"
  ],
  "comment": "Accepted for publication by the MNRAS. arXiv admin note: text overlap with arXiv:2102.02530",
  "categories": [
    "astro-ph.HE",
    "astro-ph.CO"
  ],
  "abstract": "We use Swift blazar spectra to estimate the key intergalactic medium (IGM) properties of hydrogen column density(Nhxigm), metallicity and temperature over a redshift range of 0.03 leq z leq 4.7, using a collisional ionisation equilibrium(CIE) model for the ionised plasma. We adopted a conservative approach to the blazar continuum model given its intrinsic variability and use a range of power law models. We subjected our results to a number of tests and found that the Nhxigm parameter was robust with respect to individual exposure data and co-added spectra for each source, and between Swift and XMM-Newton source data. We also found no relation between Nhxigm and variations in source flux or intrinsic power laws. Though some objects may have a bulk Comptonisation component which could mimic absorption, it did not alter our overall results. The Nhxigm from the combined blazar sample scales as(1+z)^1.8+\\-0.2. The mean hydrogen density at z = 0 is n0 = (3.2+\\-0.5) x 10^-7 cm^-3. The mean IGM temperature over the full redshift range is log(T\\K) = 6.1+\\-0.1 and the mean metallicity is [X\\H] = -1.62+\\-0.04 (Z sim0.02) When combining with the results with a gamma-ray burst (GRB) sample, we find the results are consistent over an extended redshift range of 0.03 leq z leq 6.3. Using our model for blazars and GRBs, we conclude that the IGM contributes substantially to the total absorption seen in both blazar and GRB spectra.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-09-09T10:55:51.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "intergalactic medium",
      "physical properties",
      "collisional ionisation equilibrium",
      "hydrogen column density",
      "swift blazar spectra"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}