| Autor: |
Luke Hovey, John P. Hughes, Curtis McCully, Viraj Pandya, Kristoffer Eriksen |
| Předmět: |
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| Zdroj: |
Astrophysical Journal; 8/1/2018, Vol. 862 Issue 2, p1-1, 1p |
| Abstrakt: |
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. 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). 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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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