1. Formation of Redback and Black Widow Binary Millisecond Pulsars
Kun Jia and Xiang-Dong Li
Department of Astronomy
Nanjing University
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2. Millisecond Pulsar (MSP)-Low-mass X-ray Binary (LMXB) Relation
Recycling Scenario
(Alpar 1982; Radakrishnan & Srinivasan 1982)
– Spin up to ms periods
– Magnetic field decay
High mass star PSR LMXB MSP
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3. Observational evidence for the recycling scenario
Millisecond X-ray pulsations from LMXBs
SAX J
Wijnands & van der Klis 1998
Patruno & Watts 2012
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4. Observational evidence for the recycling scenario
Transitions between rotation and accretion power in MSPs
PSR J (Archibald et al. 2009)
IGR J /PSR J1824–2452I (Papitto et al. 2013)
XSS J (Bogdanov et al. 2014)
X-ray radio
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5. The three transitional pulsars are also eclipsing MSPs
Roberts 2013
Redbacks
non-degenerate companion
(~0.2 M⊙-0.4 M⊙)
Black widows
(semi)-degenerate companion
(~0.02 M⊙-0.05 M⊙)
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6. The eclipsing material possibly originates from the companions evaporated by the high-energy particles from the MSPs
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7. Gamma-ray MSPs > ⅓ of known MSPs are Gamma-ray MSPs
For Ė>5×1033 erg/s is >¾ (!)
Most Fermi MSPs are black widows and redbacks
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8. A significant variation in the accretion rate is required to explain the transitional behavior in LMXBs.
Linares 2014
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9. The disrupted magnetic braking (MB) model (Chen et al. 2013)MB GR
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10. The irradiation-induced cyclic mass transfer model (Benvenuto et al
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11. The accretion-induced collapse (AIC) model (Smedley et al. 2015)
Collapse of an accreting white dwarf (WD) to form a MSP
The companion star becomes detached from its Roche lobe because of sudden orbital expansion
Formation rates uncertain
Difficult or impossible for the occurrence of AIC in traditional CVs
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12. Transient LMXBs
Outburst
Quiescence
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13. The parameter space for the disk instability
Covers the distribution of known redbacks
If the MSP activity switches on during the quiescent phase of LMXBs, they may evolve to be redbacks
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14. Evolution with evaporation
Evaporative wind mass loss rate
v2,esc - escape velocity at the surface of the companion star
Lp - NS’s spin-down luminosity
f - efficiency of evaporation
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15. Cases with f = 0.1
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16. Changing f and angular momettum
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17. Results
Binary evolution sensitively depends on the angular momentum of the evaporative wind and f
The redback companions
The redback orbital periods
Redback - black widow relation
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18. Conclusions
Almost all LMXBs are subject to the thermal and viscous instability during their evolution
The resultant redbacks can possess main-sequence, evolved, and (proto-)WD companions with either Roche lobe filling or under-filling
Part of redbacks may become black widows, while others form MSP/He WD binaries
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