Formation of Redback and Black Widow Binary Millisecond Pulsars Kun Jia and Xiang-Dong Li Department of Astronomy Nanjing University 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP 2
Observational evidence for the recycling scenario Millisecond X-ray pulsations from LMXBs SAX J1808.4-3658 Wijnands & van der Klis 1998 Patruno & Watts 2012 2013-04-25 2015-9-25 KIAA-WAP KIAA 3 3
Observational evidence for the recycling scenario Transitions between rotation and accretion power in MSPs PSR J1023+ 0038 (Archibald et al. 2009) IGR J18245-2452/PSR J1824–2452I (Papitto et al. 2013) XSS J12270-4859 (Bogdanov et al. 2014) 2015-9-25 X-ray radio KIAA-WAP
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⊙) 2015-9-25 KIAA-WAP
The eclipsing material possibly originates from the companions evaporated by the high-energy particles from the MSPs 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP
A significant variation in the accretion rate is required to explain the transitional behavior in LMXBs. Linares 2014 2015-9-25 KIAA-WAP
The disrupted magnetic braking (MB) model (Chen et al. 2013) MB GR 2015-9-25 KIAA-WAP
The irradiation-induced cyclic mass transfer model (Benvenuto et al 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP
Transient LMXBs Outburst Quiescence 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP
Cases with f = 0.1 2015-9-25 KIAA-WAP
Changing f and angular momettum 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP
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 2015-9-25 KIAA-WAP