Measuring the mass of the black widow PSR J1555-2908
Kennedy, Mark R.
Breton, R. P.
Clark, C. J.
Sánchez, D. Mata
Dhillon, V. S.
Halpern, J. P.
Marsh, T. R.
Ray, P. S.
Oxford University Press on behalf of the Royal Astronomical Society
star equation of state. In pulsar binaries with no measurable post-Keplerian parameters, this requires an accurate estimate of the binary system’s inclination and the radial velocity of the companion star by other means than pulsar timing. In this paper, we present the results of a new method for measuring this radial velocity using the binary synthesis code Icarus. This method relies on constructing a model spectrum of a tidally distorted, irradiated star as viewed for a given binary configuration. This method is applied to optical spectra of the newly discovered black widow PSR J1555–2908. By modelling the optical spectroscopy alongside optical photometry, we find that the radial velocity of the companion star is 397 4 km s−1 (errors quoted at 95% confidence interval), as well as a binary inclination of > 75°. Combined with γ-ray pulsation timing information, this gives a neutron star mass of 1.67+0.15 Mo and a companion mass of 0.060+0.005 Mo, placing PSR J1555–2908 at the observed upper limit of what is considered a black widow system.
Stars , Neutron , Binaries , Close , Pulsars , Individual , PSR J1555-2908 , Techniques , Spectroscopic
Kennedy, M. R., Breton, R. P., Clark, C. J., Sánchez, D. M., Voisin, G., Dhillon, V. S., Halpern, J. P., Marsh, T. R., Nieder, L., Ray, P. S. and van Kerkwijk, M. H. (2022) 'Measuring the mass of the black widow PSR J1555-2908', Monthly Notices of the Royal Astronomical Society, 512(2), pp. 3001–3014. doi: 10.1093/mnras/stac379
© 2022, the Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.