he star evolutionary channel to intermediate-mass binary pulsars with a short-orbital-period chen...
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He star evolutionary channel to intermediate-
mass binarypulsars with a short-
orbital-period Chen Wen-Cong
School of Physics, Peking University
Department of Physics, Shangqiu Normal University
Normal Radio Pulsars and Millisecond pulsars
Normal radio pulsars
MSPs
Recycled Scenario of MSPs
X-ray pulsars
Spin Periodsdeath line
Binary pulsars Low mass binary pulsars (LMBPs)
millisecond pulsar + He WD
Intermediate mass binary pulsars (IMBPs)
mildly recycled pulsar + CO/ONeMg WD
spin periods, magnetic field, and orbital eccentricities of IMBPs are considerably greater than those of LMBPs
PSR J1802-2124 circular orbit, Porb=16.8 hr Ps=12.6 ms Mp=1.24+/-0.11 Msun
M2=0.78+/-0.04 Msun, CO white dwarf
(Ferdman et al. 2010, ApJ)
Light pulsar, heavy WD, short orbital period, moderate long spin period imply that it experiences a peculiar evolutionary history
Previous works L/IMXB, Roche lobe overflow, common envelope, spiral in, s
hort timescale super-Eddington accretion (van den Heuvel 1994)
thermal-viscous instability of the accretion disks in IMXBs may result in the birth of a mildly recycled pulsar (Li 2002)
Tauris et al (2000) found that IMBPs with wide orbit (> 3 d) can be formed through a short-lived highly super-Eddington mass transfer phase
We propose that NS+He star system may be the progenitor of IMBPs with a short-orbital-period like PSR J1802-2124
Our work
Population synthesis Results:
CC: core collapse AIC: accretion induced collapse
Initial distribution of NS + He star systems
An evolutionary example to PSRJ1802-2124
Eggleton stellar code NS + He star system Eddington accretion limit Orbital angular momentum loss
Gravitational wave radiation
magnetic braking
isotropic winds
Evolutionary results
(Chen, Li & Xu 2011, A&A, in press)
Observed parameters of PSR J1802-2124:
Summary
There exist sufficient IMBPs with a short-orbital-period (SOP) in the Galaxy
NS + He star channel may be responsible for the formation of most IMBPs with a SOP.
AIC process makes a main contribution in forming SOP IMBPs
Thank you!
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