2014/09/08 by Zach Medin, Andrew Cumming
Physics and Astronomy · #Accretion (finance) #Astrophysical Phenomena and Observations #Convection #Flattening #Gamma-ray bursts and supernovae #Internal heating #Light curve #Neutron star #Pulsars and Gravitational Waves Research #Stars #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/802/1/29
22 pages, 11 figures, submitted to ApJ
arxiv created 2014/09/08 · openalex publication_date 2015/03/18 · arxiv updated 2015/06/22 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We discuss the effect of convection driven by chemical separation at the ocean–crust boundary of accreting neutron stars. We extend the steady-state results of Medin & Cumming to transient accretors, by considering the time-dependent cases of heating during accretion outbursts and cooling during quiescence. During accretion outbursts, inward heat transport has only a small effect on the temperature profile in the outer layers until the ocean is strongly enriched in light elements, a process that takes hundreds of years to complete. During quiescence, however, inward heat transport rapidly cools the outer layers of the ocean while keeping the inner layers hot. We find that this leads to a sharp drop in surface emission at around a week followed by a gradual recovery as cooling becomes dominated by the crust. Such a dip should be observable in the light curves of these neutron star transients, if enough data is taken at a few days to a month after the end of accretion. If such a dip is definitively observed, it will provide strong constraints on the chemical composition of the ocean and outer crust.