{
  "id": "1503.04780",
  "version": "v1",
  "published": "2015-03-16T19:28:17.000Z",
  "updated": "2015-03-16T19:28:17.000Z",
  "title": "On the need for simultaneity between X-ray and radio observations in Doppler factor estimates",
  "authors": [
    "I. Liodakis",
    "A. Zezas",
    "V. Pavlidou"
  ],
  "comment": "5 pages,2 figures, comments welcome",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We use archival X-ray and radio VLBA data to calculate inverse Compton Doppler factors for four high-power radio, $\\gamma$-loud Flat Spectrum Radio Quasars frequently monitored by the F-GAMMA project. We explore the effect of the non-simultaneity between X-ray and radio observations by calculating Doppler factors for simultaneous and non-simultaneous observations. By comparing the newly re-calculated values from this work and archival values with variability Doppler factors, we show that simultaneous/quasi-simultaneous X-ray and radio observations can provide a reliable estimate of the true Doppler factor in blazar jets. For the particular case of PKS0528+134 we find that a time-difference of up to 1 week provides inverse Compton Doppler factor estimates consistent with the variability Doppler factor of this source at the 19% percent level. In contrast, time differences of more than 30 days between radio and X-ray observations result to discrepancies from 100% to more than a factor of 4.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-03-16T19:28:17.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "radio observations",
      "compton doppler factor estimates",
      "doppler factor estimates consistent",
      "flat spectrum radio quasars",
      "inverse compton doppler factor"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1352794
    }
  }
}