Bibcode
Knežević, Sladjana; Läsker, Ronald; van de Ven, Glenn; Font, J.; Raymond, John C.; Bailer-Jones, Coryn A. L.; Beckman, J. E.; Morlino, Giovanni; Ghavamian, Parviz; Hughes, John P.; Heng, Kevin
Bibliographical reference
Supernova 1987A:30 years later - Cosmic Rays and Nuclei from Supernovae and their aftermaths, Proceedings of the International Astronomical Union, IAU Symposium, Volume 331, pp. 248-253
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2
2017
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Description
We present wide-field, spatially and highly resolved spectroscopic
observations of Balmer filaments in the northeastern rim of Tycho's
supernova remnant in order to investigate the signal of cosmic-ray (CR)
acceleration. The spectra of Balmer-dominated shocks (BDSs) have
characteristic narrow (FWHM ~ 10 km s-1) and broad (FWHM ~
1000 km s-1) Hα components. CRs affect the
Hα-line parameters: heating the cold neutrals in the interstellar
medium results in broadening of the narrow Hα-line width beyond 20
km s-1, but also in reduction of the broad Hα-line
width due to energy being removed from the protons in the post-shock
region. For the first time we show that the width of the narrow Hα
line, much larger than 20 km s-1, is not a resolution or
geometric effect nor a spurious result of a neglected intermediate (FWHM
~ 100 km s-1) component resulting from hydrogen atoms
undergoing charge exchange with warm protons in the broad-neutral
precursor. Moreover, we show that a narrow line width >> 20 km
s-1 extends across the entire NE rim, implying CR
acceleration is ubiquitous, and making it possible to relate its
strength to locally varying shock conditions. Finally, we find several
locations along the rim, where spectra are significantly better
explained (based on Bayesian evidence) by inclusion of the intermediate
component, with a width of 180 km s-1 on average.