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arXiv · 2312.03075

Monitoring the X-ray Variability of Bright X-ray Sources in M33

Rebecca Kyer·Shelby Albrecht·Benjamin F. Williams·Kyros Hinton·Breanna Binder·Margaret Lazzarini·Kristen Garofali·Bret Lehmer·Michael Eracleous·Paul P. Plucinsky·Vallia Antoniou
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Abstract

We present a new five-epoch Chandra X-ray Observatory monitoring survey of the nearby spiral galaxy M33 which probes X-ray variability with time sampling between two weeks and four months. We characterize the X-ray variability of 55 bright point sources outside of the nucleus, many of which are expected to be high-mass X-ray binaries (HMXBs). We detect eight new candidate transients not detected in previous X-ray catalogs of M33 and discuss their possible nature. The final catalog includes 26 known HMXB candidates identified in the literature. We extend the baseline of the X-ray light curves up to 21 years by including archival X-ray observations of these sources. We compare the detection and non-detection epochs of the sources to suites of simulated source duty cycles and infer that most of our detected sources have duty cycles > 30%. We find only four sources whose detection patterns are consistent with having duty cycles below 30%. This large fraction of sources with high duty cycles is unexpected for a population of HMXBs, thus more frequent X-ray monitoring will likely reveal many more low duty cycle HMXBs in M33.

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Rebecca Kyer, Shelby Albrecht, Benjamin F. Williams, Kyros Hinton, Breanna Binder, Margaret Lazzarini, Kristen Garofali, Bret Lehmer, Michael Eracleous, Paul P. Plucinsky, Vallia Antoniou. 2023-12-05. Monitoring the X-ray Variability of Bright X-ray Sources in M33. https://doi.org/10.3847/1538-4357%2Fad151a

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