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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Recovering Pulsar Braking Index from a Population of Millisecond Pulsars
AU - Hewitt, A. L.
AU - Pitkin, M.
AU - Hook, I. M.
PY - 2025/5/15
Y1 - 2025/5/15
N2 - The braking index, n, of a pulsar is a measure of its angular momentum loss and the value it takes to correspond to different spin-down mechanisms. For a pulsar spinning down due to gravitational-wave emission from the principal mass quadrupole mode alone, the braking index would equal exactly 5. Unfortunately, for millisecond pulsars, it can be hard to measure observationally due to the extremely small second time derivative of the rotation frequency, f̈ . This paper aims to examine whether it could be possible to extract the distribution of n for a whole population of pulsars rather than measuring the values individually. We use simulated data with an injected n = 5 signal for 47 ms pulsars and extract the distribution using hierarchical Bayesian inference methods. We find that while possible, observation times of over 20 yr and rms noise of the order of 10−5 ms are needed, which can be compared to the mean noise value of 3 × 10−4 ms for the recent wide-band 12.5 yr NANOGrav sample, which provided the pulsar timing data used in this paper.
AB - The braking index, n, of a pulsar is a measure of its angular momentum loss and the value it takes to correspond to different spin-down mechanisms. For a pulsar spinning down due to gravitational-wave emission from the principal mass quadrupole mode alone, the braking index would equal exactly 5. Unfortunately, for millisecond pulsars, it can be hard to measure observationally due to the extremely small second time derivative of the rotation frequency, f̈ . This paper aims to examine whether it could be possible to extract the distribution of n for a whole population of pulsars rather than measuring the values individually. We use simulated data with an injected n = 5 signal for 47 ms pulsars and extract the distribution using hierarchical Bayesian inference methods. We find that while possible, observation times of over 20 yr and rms noise of the order of 10−5 ms are needed, which can be compared to the mean noise value of 3 × 10−4 ms for the recent wide-band 12.5 yr NANOGrav sample, which provided the pulsar timing data used in this paper.
KW - Gravitational wave sources
KW - Neutron stars
KW - Compact objects
KW - Millisecond pulsars
KW - Gravitational waves
KW - Pulsars
KW - Stellar remnants
U2 - 10.3847/1538-4357/adc683
DO - 10.3847/1538-4357/adc683
M3 - Journal article
VL - 985
JO - The Astrophysical Journal
JF - The Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 79
ER -