X-Ray Studies of Redbacks

Abstract

We consider the X-ray properties of the redback class of eclipsing millisecond pulsars. These are transitional systems between accreting low-mass X-ray binaries and binary millisecond pulsars orbiting white dwarfs, and hence their companions are non-degenerate and nearly Roche-lobe filling. The X-ray luminosity seems to scale with the fraction of the pulsar sky subtended by the companion, suggesting the shock region is not much larger than the companion, which is supported by modeling of the orbital light curves. The typical X-ray photon spectral index is $\sim 1$ and the typical 0.3-8 keV X-ray efficiency, assuming a shock size on the order of the companion's Roche lobe cross-section, is on the order of 10%. We present an overview of previous investigations, and present new observations of two redbacks, a Chandra observation of PSR J1628$-$3205 and a XMM-Newton observation of PSR J2129$-$0429. The latter shows a clearly double peaked orbital light curve with variation of the non-thermal flux by a factor of $\sim 11$, with peaks around orbital phases 0.6 and 0.9. We suggest the magnetic field of the companion plays a significant role in the X-ray emission from intrabinary shocks in redbacks.

5 pages, 4 figures, 2014 Fermi Symposium proceedings - eConf C14102.1

References in corpus (1)

• Discovery of PSR J1227-4853: A transition from a low-mass X-ray binary to a redback millisecond pulsar

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• X-ray Sources in the Dwarf Spheroidal Galaxy Draco
• Chandra and HST Studies of Six Millisecond Pulsars in the Globular Cluster M13
• A Search for Very High-Energy Gamma Rays from the Missing Link Binary Pulsar J1023+0038 with VERITAS
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• X-Ray and Optical Properties of Black Widows and Redbacks
• Gamma-ray orbital modulation of the transitioning millisecond pulsar binary XSS J12270-4859
• High Energy Emission from Black Widows and Redbacks
• "Spider" Millisecond Pulsar Binaries as Potential TeV Emitters