The Radio Millisecond Pulsar PSR J1023+0038:

A Link to Low-Mass X-Ray Binaries

Slavko Bogdanov

Rotation-powered millisecond pulsars

Spun-up (“recycled”) by accretion of mass and angular momentum in low-mass X-ray binaries

Most are in binaries with white dwarf or very low-mass (~0.03 M) degenerate companions

To date, no accreting X-ray MSP (e.g. SAX J1808.4–3658) has been seen to turn on as a radio pulsar

SDSS J102347.6+003841 / PSR J1023+0038

V ~ 17.5 magnitude star with a solar-type spectrum and mild 0.198-day orbital variability

X-ray counterpart with non-thermal spectrum – classified as quiescent low-mass X-ray binary (Homer et al. 2005)

1.69-ms (“recycled”) rotation-powered radio pulsar in 0.198 day circular binary orbit with ~0.2 M companion, discovered in Green Bank Telescope drift scan survey (Archibald et al. 2009)

Deep radio eclipse near superior conjunction + random/irregular eclipses throughout orbit

First known radio MSP in the field of the Galaxy with non-degenerate companion star (several similar systems in globular clusters)

First radio MSP to exhibit evidence for an accretion disk (Wang et al. 2009)

Archibald et al. (2009)

2000-2001: Evidence for an Accretion Disk

Optical observations from May 2000 - Dec. 2001: blue spectrum with prominent emission lines & rapid flickering by ~1 mag

Double-peaked (asymmetric) emission lines – a hot accretion disk?

Simple disk model: – temperature range of 2000–34000 K, – disk inner and outer radii of 109 and 5.7×1010 cm– disk mass ~1023 g

No X-ray observations during 2000-2001

No evidence for disk or emission lines since May, 2002

Neutron star is currently a radio pulsar with a rotation-powered relativistic wind

Companion may still be Roche lobe filling Optical variability due to irradiation of face of

secondary star by pulsar wind.

Wang et al. (2009)

System transitioning between

LMXB and recycled rotation-powered pulsar?

H

2009-2010: X-ray Variability + Pulsations

XMM-Newton EPIC pn

Chandra ACIS-S

0.25-2.5 keV

1.4 GHz

Archibald et al. (2010)

Bogdanov et al. in prep.

OrX-ray Variability at Binary Period

Bogdanov, Grindlay, & van den Berg (2005)

PSR J0024–7204W (47 Tuc)

Bogdanov et al. (2010)

PSR J1740–5340 (NGC 6397)

PSR J1023+0038

Bogdanov et al. in prep

X-ray and Optical Variability

X-ray variability due to interaction of relativistic pulsar wind and matter from secondary star – intrabinary shock

X-ray pulsations due to heating of polar caps by magnetospheric return current or non-thermal magnetospheric emission

PSR J1740–5340

Credit:ESA/F.Ferraro

Summary

• PSR J1023+0038: First radio millisecond pulsar with evidence for a past hot (accretion?) disk

• At present, J1023+0038 is a “recycled” rotation-powered millisecond pulsar ablating its companion

• System can offer better understanding of close binary evolution, especially transition from accretion to rotation power – e.g. does SAX J1808.4-3658 turn on as a radio MSP in quiescence?

•Site for studies of relativistic outflows and shocks

•Close optical/X-ray monitoring needed to catch system in the “disk state”