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arXiv · 1811.12416

Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR

Laura A. Lopez·Brian W. Grefenstette·Katie Auchettl·Kristin K. Madsen·Daniel Castro
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Abstract

We present evidence of diffuse, non-thermal X-ray emission from the superbubble 30 Doradus C (30 Dor C) using hard X-ray images and spectra from NuSTAR observations. For this analysis, we utilize data from a 200 ks targeted observation of 30 Dor C as well as 2.8 Ms of serendipitous off-axis observations from the monitoring of nearby SN 1987A. The complete shell of 30 Dor C is detected up to 20 keV, and the young supernova remnant MCSNR J0536-6913 in the southeast of 30 Dor C is not detected above 8 keV. Additionally, six point sources identified in previous Chandra and XMM-Newton investigations have hard X-ray emission coincident with their locations. Joint spectral fits to the NuSTAR and XMM-Newton spectra across the 30 Dor C shell confirm the non-thermal nature of the diffuse emission. Given the best-fit rolloff frequencies of the X-ray spectra, we find maximum electron energies of 70-110 TeV (assuming a B-field strength of 4$μ$G), suggesting 30 Dor C is accelerating particles. Particles are either accelerated via diffusive shock acceleration at locations where the shocks have not stalled behind the H$α$ shell, or cosmic-rays are accelerated through repeated acceleration of low-energy particles via turbulence and magnetohydrodynamic waves in the bubble's interior.

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Laura A. Lopez, Brian W. Grefenstette, Katie Auchettl, Kristin K. Madsen, Daniel Castro. 2020-03-21. Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR. https://doi.org/10.3847/1538-4357%2Fab8232

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