학술논문
Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries
Document Type
Working Paper
Author
Clark, C. J.; Kerr, M.; Barr, E. D.; Bhattacharyya, B.; Breton, R. P.; Bruel, P.; Camilo, F.; Chen, W.; Cognard, I.; Cromartie, H. T.; Deneva, J.; Dhillon, V. S.; Guillemot, L.; Kennedy, M. R.; Kramer, M.; Lyne, A. G.; Sánchez, D. Mata; Nieder, L.; Phillips, C.; Ransom, S. M.; Ray, P. S.; Roberts, M. S. E.; Roy, J.; Smith, D. A.; Spiewak, R.; Stappers, B. W.; Tabassum, S.; Theureau, G.; Voisin, G.
Source
Subject
Language
Abstract
Reliable neutron star mass measurements are key to determining the equation-of-state of cold nuclear matter, but these are rare. "Black Widows" and "Redbacks" are compact binaries consisting of millisecond pulsars and semi-degenerate companion stars. Spectroscopy of the optically bright companions can determine their radial velocities, providing inclination-dependent pulsar mass estimates. While inclinations can be inferred from subtle features in optical light curves, such estimates may be systematically biased due to incomplete heating models and poorly-understood variability. Using data from the Fermi Large Area Telescope, we have searched for gamma-ray eclipses from 49 spider systems, discovering significant eclipses in 7 systems, including the prototypical black widow PSR B1957$+$20. Gamma-ray eclipses require direct occultation of the pulsar by the companion, and so the detection, or significant exclusion, of a gamma-ray eclipse strictly limits the binary inclination angle, providing new robust, model-independent pulsar mass constraints. For PSR B1957$+$20, the eclipse implies a much lighter pulsar ($M_{\rm psr} = 1.81 \pm 0.07\,M_{\odot}$) than inferred from optical light curve modelling.
Comment: 31 pages, 4 figures, includes supplementary tables; published in Nature Astronomy
Comment: 31 pages, 4 figures, includes supplementary tables; published in Nature Astronomy