Identification of the Optical Counterpart of Fermi Black Widow Millisecond Pulsar PSR J1544+4937 [HEAP]

http://arxiv.org/abs/1407.0081


We report the optical identification of the companion to the {\it Fermi} black widow millisecond pulsar PSR J1544+4937. We find a highly variable source on Keck LRIS images at the nominal pulsar position, with 2 magnitude variations over orbital period in the B, g, R, and I bands. The nearly achromatic light curves are difficult to explain with a simply irradiated hemisphere model, and suggest that the optical emission is dominated by a nearly isothermal hot patch on the surface of the companion facing the pulsar. We roughly constrain the distance to PSR J1544+4937 to be between 2 and 5 kpc. A more reliable distance measurement is needed in order to constrain the composition of the companion.

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S. Tang, D. Kaplan, S. Phinney, et. al.
Wed, 2 Jul 14
40/72

Comments: 6 pages, 4 figures, accepted for publication in ApJ Letters