Title: Constraints on Cosmic-ray Acceleration Efficiency in Balmer Shocks of Two Young Type Ia Supernova Remnants in the Large Magellanic Cloud

Abstract

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 themore » Tycho supernova remnant, where the shocks predominantly show little Hα emission, indicating that Balmer-dominated shocks are not efficient CR accelerators.« less

Authors:

Hovey, Luke ^[1]; Hughes, John P.  ^[2];

• Search DOE PAGES for author "Hughes, John P."
• Search DOE PAGES for ORCID "0000-0002-8816-6800"

McCully, Curtis  ^[3];

• Search DOE PAGES for author "McCully, Curtis"
• Search DOE PAGES for ORCID "0000-0001-5807-7893"

Pandya, Viraj  ^[4];

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• Search DOE PAGES for ORCID "0000-0002-2499-9205"

Eriksen, Kristoffer ^[1]

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Flatiron Inst., New York, NY (United States). Center for Computational Astrophysics
3. Las Cumbres Observatory, Goleta, CA (United States); Univ. of California, Santa Barbara, CA (United States). Dept. of Physics,
4. Univ. of California, Santa Cruz, CA (United States). UCO/Lick Observatory, Dept. of Astronomy and Astrophysics

Publication Date:

Wed Aug 01 00:00:00 EDT 2018

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE; National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)

OSTI Identifier:

1469544

Report Number(s):

LA-UR-17-28677
Journal ID: ISSN 1538-4357

Grant/Contract Number:  

AC52-06NA25396; HST-GO-11015.01-A; AST-1313484

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal (Online); Journal Volume: 862; Journal Issue: 2; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Astronomy and Astrophysics