The Synchrotron Emission Pattern of IntraBinary Shocks

Abstract

We model millisecond pulsars winds colliding with radiatively-driven companion winds in black widow and redback systems. For the redbacks, the geometry of this intrabinary shock (IBS) is quite sensitive to the expected equatorial concentration in the pulsar outflow. We thus analytically extend IBS thin-shock models to $\sim {\sin }^{2n}\theta$ pulsar winds. We compute the synchrotron emission from such shocks, including the build-up and cooling of the particle population as it accelerates along the IBS. For reasonable parameters, this IBS flux dominates the binary emission in the X-ray band. The modeling shows subtle variation in spectrum across the IBS peak, accessible to sensitive X-ray studies. As example applications, we fit archival CXO/XMM data from the black widow pulsar J1959+2048 and the redback PSR J2339-0533, finding that the model reproduces well the orbital light curve profiles and energy spectra. The results show a very hard injected electron spectrum, indicating likely dominance by reconnection. The light curve fitting is sensitive to the geometric parameters, including the very important orbital inclination $i$. Coupled with optical fits of the companion star, such IBS X-ray light curve modeling can strongly constrain the binary geometry and the energetics of the MSP wind.

Accepted for publication in ApJ

References in corpus (4)

• Modeling interaction of relativistic and nonrelativistic winds in binary system PSR 1259-63/SS2883. I.Hydrodynamical limit
• The light curve of the companion to PSR B1957+20
• Gamma-ray Timing of Redback PSR J2339-0533: Hints for Gravitational Quadrupole Moment Changes
• B-ducted Heating of Black Widow Companions

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• XMM-Newton Observes the Intrabinary Shock of PSR J1959+2048
• Orbital Modulation of Gamma Rays from PSR~J2339$-$0533
• NuSTAR and Parkes observations of the transitional millisecond pulsar binary XSS J12270-4859 in the rotation-powered state
• The peculiar chemical abundance of the transitional millisecond pulsar PSR J1023+0038 -- Li enhancement
• Observational connection of non-thermal X-ray emission from pulsars with their timing properties and thermal emission
• Investigation of the broadband emission of the gamma-ray binary HESS J0632+057 using an intrabinary shock model
• A puzzling 2-hour X-ray periodicity in the 1.5-hour orbital period black widow PSR J1311-3430
• Hydrodynamical simulations of wind interaction in spider systems : A step toward understanding transitional millisecond pulsars