Constraining the ellipticity of millisecond pulsars with observed spin-down rates. (arXiv:2008.02444v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Chen_W/0/1/0/all/0/1">Wen-Cong Chen</a>
A spinning neutron star (NS) that is asymmetric with respect to its spin axis
can emit continuous gravitational wave (GW) signals. The spin frequencies and
their distribution of radio millisecond pulsars (MSPs) and accreting MSPs
provide some evidences of GW radiation, and MSPs are ideal probes detecting
high frequency GW signals. It is generally thought that MSPs originate from the
recycled process, in which the NS accretes the material and angular momentum
from the donor star. The accreted matter would be confined at the polar cap
zone by an equatorial belt of compressed magnetic field fixed in the deep crust
of the NS, and yields “magnetic mountain”. Based on an assumption that the
spin-down rates of three transitional MSPs including PSR J1023+0038 are the
combinational contribution of the accretion torque, the propeller torque, and
the GW radiation torque, in this work we attempt to constrain the ellipticities
of MSPs with observed spin-down rates. Assuming some canonical parameters of
NSs, the ellipticities of three transitional MSPs and ten redbacks are
estimated to be $epsilon=(0.9-23.4)times 10^{-9}$. The electrical
resistivities of three transitional MSPs are also derived to be in the range
$eta=(1.2-15.3)times 10^{-31}~rm s$, which display an ideal power law
relation with the accretion rate. The characteristic strains ($h_{rm
c}=(0.6-2.5)times10^{-27}$) of GW signals emitting by these sources are
obviously beyond the sensitivity scope of the aLIGO. We expect that the
third-generation GW detectors like the Einstein Telescope can seize the GW
signals from these sources in the future.
A spinning neutron star (NS) that is asymmetric with respect to its spin axis
can emit continuous gravitational wave (GW) signals. The spin frequencies and
their distribution of radio millisecond pulsars (MSPs) and accreting MSPs
provide some evidences of GW radiation, and MSPs are ideal probes detecting
high frequency GW signals. It is generally thought that MSPs originate from the
recycled process, in which the NS accretes the material and angular momentum
from the donor star. The accreted matter would be confined at the polar cap
zone by an equatorial belt of compressed magnetic field fixed in the deep crust
of the NS, and yields “magnetic mountain”. Based on an assumption that the
spin-down rates of three transitional MSPs including PSR J1023+0038 are the
combinational contribution of the accretion torque, the propeller torque, and
the GW radiation torque, in this work we attempt to constrain the ellipticities
of MSPs with observed spin-down rates. Assuming some canonical parameters of
NSs, the ellipticities of three transitional MSPs and ten redbacks are
estimated to be $epsilon=(0.9-23.4)times 10^{-9}$. The electrical
resistivities of three transitional MSPs are also derived to be in the range
$eta=(1.2-15.3)times 10^{-31}~rm s$, which display an ideal power law
relation with the accretion rate. The characteristic strains ($h_{rm
c}=(0.6-2.5)times10^{-27}$) of GW signals emitting by these sources are
obviously beyond the sensitivity scope of the aLIGO. We expect that the
third-generation GW detectors like the Einstein Telescope can seize the GW
signals from these sources in the future.
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