Confirmation of the 62 Day X-Ray Periodicity from M82

TL;DR

This study confirms a 62-day X-ray periodicity in M82 using extensive monitoring data, supporting the hypothesis that it results from orbital motion in an X-ray binary system.

Contribution

It provides the first confirmation of the 62-day periodicity with high significance and coherence, strengthening the orbital motion interpretation.

Findings

Confirmed the 62-day periodicity with high significance

Observed a sinusoidal light curve with consistent amplitude

Estimated a very low probability of chance occurrence (6E-7)

Abstract

Using 400 days of new X-ray monitoring of M82, we confirm the 62 day periodicity previously reported. In the full data set spanning 1124 days, we find a period of 62.0 +/- 0.3 days and a coherence, Q = 22.3, that is consistent with a strictly periodic signal. We estimate that the probability of chance occurrence of our observed signal is 6E-7. The light curve folded at this period is roughly sinusoidal and has a peak to peak amplitude of (0.99 +/- 0.10) x 10^-11 erg cm^-2 s^-1. Confirmation of the periodicity strengthens our previous suggestion that the 62 day modulation is due to orbital motion within an X-ray binary.