A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747

Lam, M.T. and Ellis, J.A. and Grillo, G. and Jones, M.L. and Hazboun, J.S. and Pennucci, Timothy Thomas (2018) A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747. ASTROPHYSICAL JOURNAL, 861 (2). ISSN 1538-4357

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Abstract

The frequency dependence of radio pulse arrival times provides a probe of structures in the intervening media. Demorest et al. was the first to show a short-term (similar to 100-200 days) reduction in the electron content along the line of sight to PSR. J1713+0747 in data from 2008 (approximately MJD 54750) based on an apparent dip in the dispersion measure of the pulsar. We report on a similar event in 2016 (approximately MJD 57510), with average residual pulse-arrival times approximate to-3.0, -1.3, and -0.7 mu s at 820, 1400, and 2300. MHz, respectively. Timing analyses indicate possible departures from the standard v(-2) dispersive-delay dependence. We discuss and rule out a wide variety of potential interpretations. We find the likeliest scenario to be lensing of the radio emission by some structure in the interstellar medium, which causes multiple frequency-dependent pulse arrival-time delays.

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