Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR. (arXiv:1811.12416v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lopez_L/0/1/0/all/0/1">Laura A. Lopez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grefenstette_B/0/1/0/all/0/1">Brian W. Grefenstette</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Auchettl_K/0/1/0/all/0/1">Katie Auchettl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Madsen_K/0/1/0/all/0/1">Kristin K. Madsen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Castro_D/0/1/0/all/0/1">Daniel Castro</a>
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.
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.
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