2001MNRAS.325.1157U -
Mon. Not. R. Astron. Soc., 325, 1157-1166 (2001/August-2)
Time-variable emission from transiently accreting neutron stars in quiescence due to deep crustal heating.
USHOMIRSKY G. and RUTLEDGE R.E.
Abstract (from CDS):
Transiently accreting neutron stars in quiescence (LX≲1034erg.s–1) have been observed to vary in intensity by factors of few, over time-scales of days to years. If the quiescent luminosity is powered by a hot neutron star core, the core cooling time-scale is much longer than the recurrence time, and cannot explain the observed, more rapid variability. However, the non-equilibrium reactions which occur in the crust during outbursts deposit energy in isodensity shells, from which the thermal diffusion time-scale to the photosphere is days to years. The predicted magnitude of variability is too low to explain the observed variability unless - as is widely believed - the neutrons beyond the neutron-drip density are superfluid. Even then, the variability due to this mechanism in models with standard core neutrino cooling processes is less than 50 per cent - still too low to explain the reported variability. However, models with rapid core neutrino cooling can produce a variability by a factor as great as 20, on time-scales of days to years following an outburst. Thus, the factors of ∼few intensity variability observed from transiently accreting neutron stars can be accounted for by this mechanism only if rapid core cooling processes are active.
Abstract Copyright:
The Royal Astronomical Society
Journal keyword(s):
nuclear reactions, nucleosynthesis, abundances - stars: neutron - X-rays: binaries
CDS comments:
4U 2129+37 is a misprint for 4U 2129+47.
Simbad objects:
6
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