ASD Colloquium
Tuesday · 03:30 PM - 05:00 PM
Hidden Engines in Supernova Remnants: Accretion-Powered Sources in M83 and Beyond
Andrea Prestwich (NASA GSFC, 661)
Recent work on long-term X-ray variability in the nearby spiral galaxy M83 has revealed an unexpected result: a significant fraction of sources classified as supernova remnants (SNRs) exhibit substantial variability on decade timescales. This is surprising because soft X-ray emission from remnants older than ~100 years is expected to evolve smoothly, changing little over such periods. The observed light curves and spectra are difficult to reconcile with standard SNR evolution models, and may point to the presence of accretion-powered sources physically associated with the remnants. Possible explanations include fallback accretion onto the compact object formed in the explosion, or an X-ray binary associated with the remnant — though neither interpretation is without difficulty. The variable sources are statistically correlated with high-mass stars, and their luminosities and spectral properties are broadly consistent with cool accretion disks around stellar-mass black holes, but the current data do not uniquely determine the nature of these systems. The origin of the variability remains an open question.
I will close with a brief look at preliminary efforts to find similar systems in other galaxies. Sources with broadly similar properties have been identified in M51, and we are using eROSITA to search for soft, variable sources near known SNRs in the Large Magellanic Cloud. Several candidates have emerged for further study, though none yet constitute a convincing match to the class of sources seen in M83. The frequency of such systems in the LMC appears to be substantially lower than in M83.
