I. Cognard, Paulo Freire, L. Guillemot, G. Theureau, T.M. Tauris, Norbert Wex, E. Graikou, Michael Kramer, Benjamin Stappers, Andrew Lyne, Cees Bassa, G Desvignes, Patrick Lazarus

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    We report on the results of a 4-year timing campaign of PSR J2222-0137, a 2.44-day binary pulsar with a massive white dwarf (WD) companion, with the Nançay, Effelsberg and Lovell radio telescopes. Using the Shapiro delay for this system, we find a pulsar mass mp = 1:76 0:06M and a WD mass mc = 1:293 0:025M. We also measure the rate of advance of periastron for this system, which is marginally consistent with the GR prediction for these masses. The short lifetime of the massive WD progenitor star led to a rapid X-ray binary phase with little (< 10-2M) mass accretion onto the neutron star (NS); hence, the current pulsar mass is, within uncertainties, its birth mass; the largest measured to date. We discuss the discrepancy with previous mass measurements for this system; we conclude that the measurements presented here are likely to be more accurate. Finally, we highlight the usefulness of this system for testing alternative theories of gravity by tightly constraining the presence of dipolar radiation. This is of particular importance for certain aspects of strong-field gravity, like spontaneous scalarization, since the mass of PSR J2222-0137 puts that system into a poorly tested parameter range.
    Original languageEnglish
    JournalThe Astrophysical Journal
    Publication statusPublished - 31 Jul 2017


    • pulsars: general
    • pulsars: individual J222-0137
    • stars: neutron star
    • white dwarfs
    • Binaries: close
    • X-rays: binaries


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