{
  "id": "2111.11953",
  "version": "v1",
  "published": "2021-11-23T15:46:58.000Z",
  "updated": "2021-11-23T15:46:58.000Z",
  "title": "Timing and Spectral Analysis of HMXB OAO 1657-415 with NuSTAR",
  "authors": [
    "Prince Sharma",
    "Rahul Sharma",
    "Chetana Jain",
    "Anjan Dutta"
  ],
  "comment": "Accepted for publication in MNRAS",
  "doi": "10.1093/mnras/stab3436",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "This work presents a comprehensive timing and spectral analysis of high-mass X-ray binary pulsar, OAO 1657-415 by using the observation made with Nuclear Spectroscopic Telescope Array (NuSTAR) on June 2019. During this observation, OAO 1657-415 exhibited X-ray variability by a factor of about 3. X-ray pulsations at 37.03322(14) s were observed up to 70 keV. OAO 1657-415 was undergoing a spin-down phase with $\\dot{P} = 9(1) \\times 10^{-8}$ s s$^{-1}$. This is an order of about 100 larger than the long-term spin-up rate. The pulse profile evolved marginally during the observation. We have discussed the long-term pulse period history of the source spanning a time-base of 43 years, including the latest Fermi/GBM data. The 3-70 keV source spectrum is described by a partially covered cutoff power-law, an Fe K$_{\\alpha}$ line at 6.4 keV and a Compton shoulder at 6.3 keV. We report the presence of a cyclotron absorption feature around 40 keV, which is indicative of a surface magnetic field strength of $3.59 \\pm 0.06 \\ (1 + z)^{-1} \\times 10^{12}$ and $3.29_{-0.22}^{+0.23} \\ (1 + z)^{-1} \\times 10^{12}$ G. This work shows the first robust presence of cyclotron absorption feature in the source.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-11-23T15:46:58.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spectral analysis",
      "hmxb oao",
      "cyclotron absorption feature",
      "surface magnetic field strength",
      "high-mass x-ray binary pulsar"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}