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

Lopez, Laura A. and Grefenstette, Brian W. and Auchettl, Katie and Madsen, Kristin K. and Castro, Daniel (2018) Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR. . (Unpublished)

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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 55-102 TeV, suggesting 30 Dor C is accelerating particles despite the relatively slow H-alpha shell velocity observed in the optical. Consequently, either the particles are accelerated via diffusive shock acceleration at locations where the shocks have not stalled behind the H-alpha shell, or cosmic-rays are accelerated through repeated acceleration of low-energy particles via turbulence and magnetohydrodynamic waves in the bubble's interior.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Grefenstette, Brian W.0000-0002-1984-2932
Madsen, Kristin K.0000-0003-1252-4891
Additional Information:We thank Parviz Ghavamian, Maria Haupt, and Steve Reynolds for useful discussions and Annie Hughes for sharing the ATCA and Parkes survey data of the LMC. Additionally, we thank Daniel Wik for assistance with nuskybgd. We also acknowledge the continued work of the astronomical community contributing to AstroLib. Our work was supported under NASA contract NNG08FD60C and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by NASA. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of these observations. This research made use of the NuSTAR Data Analysis Software (NuSTARDAS), jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA).
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:acceleration of particles - ISM: bubbles - X-rays: ISM
Record Number:CaltechAUTHORS:20190620-154339961
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96609
Deposited By: Tony Diaz
Deposited On:20 Jun 2019 22:48
Last Modified:03 Oct 2019 21:23

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