paper

J0453+1559: a neutron star-white dwarf binary from a thermonuclear electron-capture supernova?

arXiv:1909.12318 · doi:10.3847/2041-8213/ab5642

Abstract

The compact binary radio pulsar system J0453+1559 (Martinez et al. 2015) consists of a recycled pulsar as primary component of and an unseen companion star of . Because of the relatively large orbital eccentricity of , it was argued that the companion is a neutron star, making it the neutron star with the lowest accurately determined mass to date. However, a direct observational determination of the nature of the companion is currently not feasible. Moreover, state-of-the-art stellar evolution and supernova modeling are contradictive concerning the possibility to produce such a low-mass neutron star remnant. Here we challenge the neutron star interpretation by reasoning that the lower-mass component could instead be a white dwarf born in a thermonuclear electron-capture supernova (tECSN) event, in which oxygen-neon deflagration in the degenerate stellar core of an ultra-stripped progenitor ejects several of matter and leaves a bound ONeFe white dwarf as the second-formed compact remnant. We determine the ejecta mass and remnant kick needed in this scenario to explain the properties of PSR~J0453+1559 by a neutron star--white dwarf system. More work on tECSNe is needed to assess the viability of this scenario.

ApJL, accepted for publication (6 pages, 4 figures)

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