An active, asynchronous companion to a redback millisecond pulsar

Abstract

PSR\,J1723$-$2837 is a "redback" millisecond pulsar (MSP) with a low-mass companion in a 14.8\,h orbit. The system's properties closely resemble those of "transitional" MSPs that alternate between spin-down and accretion-powered states. In this paper we report on long-term photometry of the 15.5\,mag companion to the pulsar. We use our data to illustrate that the star experiences sporadic activity, which we attribute to starspots. We also find that the companion is not tidally locked and infer $P_{\mathrm{s}}/P_{\mathrm{b}}=0.9974(7)$ for the ratio between the rotational and orbital periods. Finally, we place constraints on various parameters, including the irradiation efficiency and pulsar mass. We discuss similarities with other redback MSPs and conclude that starspots may provide the most likely explanation for the often seen irregular and asymmetric optical lightcurves.

Accepted in ApJL. 7 pages in aastex6 two-column format. v2 matches the published version

References in corpus (8)

• A Radio Pulsar/X-ray Binary Link
• Discovery of PSR J1227-4853: A transition from a low-mass X-ray binary to a redback millisecond pulsar
• NuSTAR Observations of the State Transition of Millisecond Pulsar Binary PSR J1023+0038
• A Spectroscopic Study of the Extreme Black Widow PSR J1311-3430
• Gamma-ray Timing of Redback PSR J2339-0533: Hints for Gravitational Quadrupole Moment Changes
• Unveiling the redback nature of the low-mass X-ray binary XSSJ1227.0-4859 through optical observations
• 21-year timing of the black-widow pulsar J2051-0827
• Optical Counterparts of Two Fermi Millisecond Pulsars: PSR J1301+0833 and PSR J1628-3205

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• Properties of the redback millisecond pulsar binary 3FGL J0212.1+5320
• 2FGL J0846.0+2820: A new neutron star binary with a giant secondary and variable $\gamma$-ray emission