Evolution of X-ray Binaries and the Formation of Binary Pulsars Xiang-Dong Li Department of Astronomy Nanjing University 2011-5-11 NAOC

Millisecond Pulsar (MSP)-X-ray Binary (XRB) Relation ATNF PSR Database 2011-5-11 NAOC

Spin Frequency Distribution in LMXBs 2011-5-11 NAOC

Binary Pulsar Populations Main type Sub-type Observational examples Recycled PSR + low-mass comp.(MC≤ 0.45M⊙) PSR + (He) WD PSR J0437-4715 PSR J1640+2224 Mildly recycled PSR + high-mass compact comp. (0.5≤MC/M⊙≤1.4) 1. PSR + NS (double) 2. PSR + (ONeMg) WD 3. PSR + (CO) WD 1. PSR B1913+16 2. PSR J1435-6100 3. PSR J2145-0750 Non-recycled pulsar (CO) WD + PSR PSR B2303+46 Un-evolved companion 1. PSR + B-type comp. 2. PSR + low-mass MS comp. 1. PSR B1259-63 2. PSR B1820-11 2011-5-11 NAOC

Binary Pulsar Populations From Breton (2009) 2011-5-11 NAOC

Classification of X-ray Binaries High-mass X-ray binaries (wind-fed X-ray sources) Supergiant HMXBs Be/X-ray binaries Intermediate-mass X-ray binaries Low-mass X-ray binaries (disk-fed X-ray sources) 2011-5-11 NAOC

Stability of Mass Transfer The characteristics of binary pulsars depends on mass transfer processes during the XRB phase The stability of mass transfer depends on The mass ratio of the donor and accretor The evolutionary state of the donor 2011-5-11 NAOC

Ways of Mass Transfer in XRBs Stable mass transfer on nuclear timescale Thermal timescale mass transfer Unstable mass transfer  common envelope low-mass donors before evolving significantly up the RGB. The smaller q values in such systems produce stable mass transfer and at these shorter contact Porb, J-loss mechanisms [specifically magnetic braking] dominate over the donor’s nuclear evolution and this provides the driver for continued mass loss. The Mdot rates are low enough that x2 ≈ xeq > 0, resulting in contraction and evolution to shorter Porb. low-mass systems that initiate mass transfer on one of the giant branches. Again, q is small leading to stable mass transfer. Continued mass transfer is driven by the donor’s nuclear evolution and resulting expansion during the giant phases. This drives the system to wider orbital separations and, typically, longer Porb. Deloye (2008) 2011-5-11 NAOC

Initial – Final Binary Relation Tauris & Savonije (2000) 2011-5-11 NAOC

HMXB Evolution Single mildly recycled NS 2011-5-11 NAOC

Evolution of LMXBs Wide recycled PSR + He WD binary Nuclear evolution-driven mass transfer Close recycled PSR + He WD binary Angular momentum-driven mass transfer Ultracompact X-ray binary or black widow X-ray binary 2011-5-11 NAOC

Evolution of IMXBs IMXB LMXB 2011-5-11 NAOC

Binary Pulsars Evolved from I/LMXBs IMXBs From Podsiadlowski et al. (2001) 2011-5-11 NAOC

Other Possibilities 2011-5-11 NAOC

Comparison with Observations RGB/AGB PSR J1903+0327 Ps=2.15 ms Porb=95 days Mpsr~1.74 Msun M2>0.88 Msun e = 0.44! Comparison with Observations TTMT There is a significant population of bPSRs systems generally consistent with being progeny of giant-branch or post thermal time-scale mass transfer systems at 1d . Porb . 100d. However, bPSRs with Porb & 100d generally have M2 smaller than predicted by theory and there are a cluster of MSPs between 0.1d . Porb . 1d that are inconsistent with being progeny of any elucidated class of LMXBs. CV-like UC-LMXBs 2011-5-11 NAOC

Mass Accretion and Mass Loss during LMXB Evolution Zhang et al. (2011) 2011-5-11 NAOC

Conclusions The standard model for H/I/LMXBs can roughly reproduce the main features of the observed binary pulsars. However, there are still many unresolved issues… 2011-5-11 NAOC