{
  "id": "1909.06163",
  "version": "v1",
  "published": "2019-09-13T12:18:30.000Z",
  "updated": "2019-09-13T12:18:30.000Z",
  "title": "Upgraded Giant Metrewave Radio Telescope timing of NGC 1851A: a possible millisecond pulsar-neutron star system",
  "authors": [
    "Alessandro Ridolfi",
    "Paulo C. C. Freire",
    "Yashwant Gupta",
    "Scott M. Ransom"
  ],
  "comment": "16 pages, 6 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.HE",
    "gr-qc"
  ],
  "abstract": "(abridged) In this work we present the results of one year of upgraded Giant Metrewave Radio Telescope timing measurements of PSR~J0514$-$4002A, a 4.99-ms pulsar in a 18.8-day, eccentric ($e \\, =\\, 0.89$) orbit with a massive companion located in the globular cluster NGC~1851. Combining these data with earlier Green Bank Telescope data, we greatly improve the precision of the rate of advance of periastron, $\\dot{\\omega} \\, = \\, 0.0129592(16)\\, \\deg \\, \\rm yr^{-1}$ which, assuming the validity of general relativity, results in a much refined measurement of the total mass of the binary, $M_{\\rm tot} \\, = \\, 2.4730(6) \\, M_{\\odot}$. Additionally, we measure the Einstein delay parameter, $\\gamma\\,, = \\, 0.0216(9) \\, \\rm s$. Furthermore, we measure the proper motion of the system ($\\mu_{\\alpha} \\, = \\, 5.19(22)$ and $\\mu_{\\delta} = -0.56(25)\\rm~mas ~ yr^{-1}$), which is not only important for analyzing its motion in the cluster, but is also essential for a proper interpretation of $\\gamma$, given the latter parameter's correlation with the variation of the projected semi-major axis. The measurements of $\\gamma$ and the proper motion enable a separation of the system component masses: we obtain a pulsar mass of $M_{p} \\, = \\, 1.25^{+0.05}_{-0.06} \\, M_{\\odot}$ and a companion mass of $M_{c} \\, = \\, 1.22^{+0.06}_{-0.05} \\, M_{\\odot}$. This raises the possibility that the companion is also a neutron star. Searches for radio pulsations from the companion have thus far been unsuccessful, hence we cannot confirm the latter hypothesis. The low mass of this millisecond pulsar - one of the lowest ever measured for such objects - clearly indicates that the recycling process can be achieved with a relatively small amount of mass transfer.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-09-13T12:18:30.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "upgraded giant metrewave radio telescope",
      "giant metrewave radio telescope timing",
      "millisecond pulsar-neutron star system"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}