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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 (2020) Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR. Astrophysical Journal, 893 (2). Art. No. 144. ISSN 1538-4357.

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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 ≈70–110 TeV (assuming a B-field strength of 4 μG), 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 Hα 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:Article
Related URLs:
URLURL TypeDescription Paper
Lopez, Laura A.0000-0002-1790-3148
Grefenstette, Brian W.0000-0002-1984-2932
Madsen, Kristin K.0000-0003-1252-4891
Additional Information:© 2020 The American Astronomical Society. Received 2018 November 30; revised 2020 March 19; accepted 2020 March 21; published 2020 April 24. 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). Support for this work was provided by National Aeronautics and Space Administration through Chandra Award Number G08–19062X and through Smithsonian Astrophysical Observatory contract SV3–73016 to MIT issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8–03060. Software: CIAO (v4.7; Fruscione et al. 2006), XSPEC (v12.9.0; Arnaud 1996), ftools (Blackburn 1995), NuSTAR Data Analysis Software (v1.8.0), XMM-NewtonSAS (v15.0.0; Gabriel et al. 2004).
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Smithsonian Astrophysical ObservatorySV3-73016
Subject Keywords:Shocks ; X-ray astronomy ; Interstellar medium ; Superbubbles
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Shocks (2086); X-ray astronomy (1810); Interstellar medium (847); Superbubbles (1656)
Record Number:CaltechAUTHORS:20190620-154339961
Persistent URL:
Official Citation:Laura A. Lopez et al 2020 ApJ 893 144
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:24 Apr 2020 17:27

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