1. Evolution of X-ray Binaries and the Formation of Binary Pulsars
Xiang-Dong Li
Department of Astronomy
Nanjing University
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2. Millisecond Pulsar (MSP)-X-ray Binary (XRB) Relation
ATNF PSR Database
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3. Spin Frequency Distribution in LMXBs
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4. Binary Pulsar Populations
Main type
Sub-type
Observational examples
Recycled PSR + low-mass comp.(MC≤ 0.45M⊙)
PSR + (He) WD
PSR J
PSR J
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 B
2. PSR J
3. PSR J
Non-recycled pulsar
(CO) WD + PSR
PSR B
Un-evolved companion
1. PSR + B-type comp.
2. PSR + low-mass MS comp.
1. PSR B
2. PSR B
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5. Binary Pulsar Populations
From Breton (2009)
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6. 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)
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7. 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
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8. 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)
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9. Initial – Final Binary Relation
Tauris & Savonije (2000)
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10. HMXB Evolution
Single mildly recycled NS
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11. 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
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12. Evolution of IMXBs
IMXB
LMXB
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13. Binary Pulsars Evolved from I/LMXBs
IMXBs
From Podsiadlowski et al. (2001)
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14. Other Possibilities
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15. Comparison with Observations
RGB/AGB
PSR J
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
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16. Mass Accretion and Mass Loss during LMXB Evolution
Zhang et al. (2011)
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17. 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…
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