Constraints on Cosmic-ray Acceleration Efficiency in Balmer Shocks of Two Young Type Ia Supernova Remnants in the Large Magellanic Cloud
[2];
[3];
[4];
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Flatiron Inst., New York, NY (United States). Center for Computational Astrophysics
- Las Cumbres Observatory, Goleta, CA (United States); Univ. of California, Santa Barbara, CA (United States). Dept. of Physics,
- Univ. of California, Santa Cruz, CA (United States). UCO/Lick Observatory, Dept. of Astronomy and Astrophysics
We present results from an optical study of two young Balmer-dominated remnants of SNIa in the Large Magellanic Cloud, 0509-67.5 and 0519-69.0, in an attempt to search for signatures of efficient cosmic-ray (CR) acceleration. Here, we combine proper motion measurements with corresponding optical spectroscopic measurements of the Hα line at multiple rim positions from VLT/FORS2 and SALT/RSS and compare our results to published Balmer shock models. Analyses of the optical spectra result in broad Hα widths in the range of 1800–4000 km s-1 for 12 separate Balmer-dominated filaments that show no evidence for forbidden line emission; the corresponding shock speeds from proper motion measurements from HST span a range of 1700–8500 km s-1. Our measured values of shock speeds and broad Hα widths in 0509-67.5 and 0519-69.0 are fit well with a Balmer shock model that does not include effects of efficient CR acceleration. We determine an upper limit of 7%/χ (95% confidence) on the CR acceleration efficiency for our ensemble of data points, where χ is the ionization fraction of the pre-shock gas. The upper limits on the individual remnants are 6%/χ (0509-67.5) and 11%/χ (0519-69.0). Finally, these upper limits are below the integrated CR acceleration efficiency in the Tycho supernova remnant, where the shocks predominantly show little Hα emission, indicating that Balmer-dominated shocks are not efficient CR accelerators.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE; National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)
- Grant/Contract Number:
- AC52-06NA25396; HST-GO-11015.01-A; AST-1313484
- OSTI ID:
- 1469544
- Report Number(s):
- LA-UR-17-28677
- Journal Information:
- The Astrophysical Journal (Online), Vol. 862, Issue 2; ISSN 1538-4357
- Publisher:
- Institute of Physics (IOP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Optical Tomography of Chemical Elements Synthesized in Type Ia Supernovae
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journal | July 2019 |
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