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

• Published in: arXiv.org 2018-07
• Main Authors: Lam, M T, Ellis, J A, Grillo, G, Jones, M L, Hazboun, J S, Brook, P R, Turner, J E, Chatterjee, S, Cordes, J M, Lazio, T J W, DeCesar, M E, Arzoumanian, Z, Blumer, H, Cromartie, H T, Demorest, P B, Dolch, T, Ferdman, R D, Ferrara, E C, Fonseca, E, Garver-Daniels, N, Gentile, P A, Gupta, V, Lorimer, D R, Lynch, R S, Madison, D R, McLaughlin, M A, C Ng, Nice, D J, Pennucci, T T, Ransom, S M, Spiewak, R, Stairs, I H, Stinebring, D R, Stovall, K, Swiggum, J K, Vigeland, S J, Zhu, W W
• Format: Article
• Language: English
• Subjects: Dispersion; Interstellar matter; Pulsars; Radio emission; Time dependence
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1712.03651

The frequency dependence of radio pulse arrival times provides a probe of structures in the intervening media. Demorest et al. 2013 was the first to show a short-term (~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 of approximately 3.0,-1.3, and -0.7 microseconds at 820, 1400, and 2300 MHz, respectively. Timing analyses indicate possible departures from the standard nu^-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.