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., Ng, C., 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. and Zhu, W. W.
(2018)
A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747.
Astrophysical Journal, 861.
ISSN 0004-637X
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 (~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 ≈−3.0, −1.3, and −0.7 μs at 820, 1400, and 2300 MHz, respectively. Timing analyses indicate possible departures from the standard ν −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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