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

Abstract

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, t <~ 10^3 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 ~ 10^3-10^4 years.

14 pages, 700 KB. Accepted by MNRAS on 2012 April 3, in press

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Cited by in corpus (14)

• 45 Years of Rotation of the Crab Pulsar
• The fate of fallback matter around newly born compact objects
• Long-period Pulsars as Possible Outcomes of Supernova Fallback Accretion
• Limits on Planet Formation Around Young Pulsars and Implications for Supernova Fallback Disks
• Rotational evolution of magnetars in the presence of a fallback disk
• On The Evolution of The Radio Pulsar PSR J1734-3333
• Population synthesis of young isolated neutron stars: the effect of fallback disk accretion and magnetic field evolution
• Ultra-luminous X-ray sources as super-critical propellers
• The Vela Pulsar With an Active Fallback Disk
• Measuring the Non-Axially-Symmetric Surface Temperature Distribution of the Central Compact Object in Puppis A
• On the long-term evolution of rotating radio transients
• Unifying neutron star sub-populations in the supernova fallback accretion model
• Is PSR J0726-2612 a dim isolated neutron star progenitor?
• Braking index of the frequently glitching PSR J0537$-$6910