The influence of fallback discs on the spectral and timing properties of neutron stars

Fallback discs around neutron stars (NSs) are believed to be an expected outcome of supernova explosions. Here we investigate the consequences of such a common outcome for the timing and spectral properties of the associated NS population, using Monte Carlo population synthesis models. We find that...

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Main Authors: Yan, T., Perna, R., Soria, Roberto
Format: Journal Article
Published: Wiley-Blackwell Publishing Ltd. 2012
Online Access:http://hdl.handle.net/20.500.11937/38179
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author Yan, T.
Perna, R.
Soria, Roberto
author_facet Yan, T.
Perna, R.
Soria, Roberto
author_sort Yan, T.
building Curtin Institutional Repository
collection Online Access
description Fallback discs around neutron stars (NSs) are believed to be an expected outcome of supernova explosions. Here we investigate the consequences of such a common outcome for the timing and spectral properties of the associated NS population, using Monte Carlo population synthesis models. We find that the long-term torque exerted by the fallback disc can substantially influence the late-time period distribution, but with quantitative differences which depend on whether the initial spin distribution is dominated by slow or fast pulsars. For the latter, a single-peaked initial spin distribution becomes bimodal at later times. Timing ages tend to underestimate the real age of older pulsars, and overestimate the age of younger ones. Braking indices cluster in the range 1.5 ˂ ~n ˂ ~3 for slow-born pulsars, and −0.5 ˂ ~n ˂ ~5 for fast-born pulsars, with the younger objects found predominantly below n ˂ ~ 3. Large values of n, while not common, are possible, and associated with torque transitions in the NS+disc system. The 0.1–10 keV thermal luminosity of the NS+disc system is found to be generally dominated by the disc emission at early times, Graphic yr, but this declines faster than the thermal surface emission of the NS. Depending on the initial parameters, there can be occasional periods in which some NSs switch from the propeller to the accretion phase, increasing their luminosity up to the Eddington limit for ∼103–104 years.
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spelling curtin-20.500.11937-381792017-09-13T14:12:15Z The influence of fallback discs on the spectral and timing properties of neutron stars Yan, T. Perna, R. Soria, Roberto Fallback discs around neutron stars (NSs) are believed to be an expected outcome of supernova explosions. Here we investigate the consequences of such a common outcome for the timing and spectral properties of the associated NS population, using Monte Carlo population synthesis models. We find that the long-term torque exerted by the fallback disc can substantially influence the late-time period distribution, but with quantitative differences which depend on whether the initial spin distribution is dominated by slow or fast pulsars. For the latter, a single-peaked initial spin distribution becomes bimodal at later times. Timing ages tend to underestimate the real age of older pulsars, and overestimate the age of younger ones. Braking indices cluster in the range 1.5 ˂ ~n ˂ ~3 for slow-born pulsars, and −0.5 ˂ ~n ˂ ~5 for fast-born pulsars, with the younger objects found predominantly below n ˂ ~ 3. Large values of n, while not common, are possible, and associated with torque transitions in the NS+disc system. The 0.1–10 keV thermal luminosity of the NS+disc system is found to be generally dominated by the disc emission at early times, Graphic yr, but this declines faster than the thermal surface emission of the NS. Depending on the initial parameters, there can be occasional periods in which some NSs switch from the propeller to the accretion phase, increasing their luminosity up to the Eddington limit for ∼103–104 years. 2012 Journal Article http://hdl.handle.net/20.500.11937/38179 10.1111/j.1365-2966.2012.21051.x Wiley-Blackwell Publishing Ltd. fulltext
spellingShingle Yan, T.
Perna, R.
Soria, Roberto
The influence of fallback discs on the spectral and timing properties of neutron stars
title The influence of fallback discs on the spectral and timing properties of neutron stars
title_full The influence of fallback discs on the spectral and timing properties of neutron stars
title_fullStr The influence of fallback discs on the spectral and timing properties of neutron stars
title_full_unstemmed The influence of fallback discs on the spectral and timing properties of neutron stars
title_short The influence of fallback discs on the spectral and timing properties of neutron stars
title_sort influence of fallback discs on the spectral and timing properties of neutron stars
url http://hdl.handle.net/20.500.11937/38179