Significance of far-ultraviolet studies through observations of two galactic supernova remnants

Abstract

Recently, it has been thought that a comprehensive understanding of supernova remnant evolution is possible only through multi-wavelength studies. However, previous far-ultraviolet observations of supernova remnants have been very rare and restricted to within only a small portion of target areas. For only four nearby supernova remnants, the results of far-ultraviolet observations of each whole area have been published recently using the FIMS/SPEAR instrument. In this thesis, the results of far-ultraviolet observations made for two other nearby supernova remnants (the Monogem Ring and RCW 114) are presented from the data of the same instrument. Unlike other famous and bright supernova remnants, neither supernova remnant is bright and, hence, has ever been analyzed deeply in various wavelength domains. This is because the Monogem Ring has been evolving in an extremely low-density ambient interstellar medium; on the other hand, RCW 114 has already evolved and cooled too much. Nevertheless, this study of far-ultraviolet observations reveals their identifications and interactions with their ambient interstellar medium, which have never been revealed clearly. Most of missing supernova remnants in the Galaxy is likely to be in situations like the above two supernova remnants. The results of both supernova remnants in this thesis show that far-ultraviolet observations can be an alternative to reveal those missing supernova remnants. Although the interstellar extinction creates large limitations, the far-ultraviolet observations of supernova remnants are expected to contribute partially, but significantly, to the study of supernova remnant evolution. With this motivation, a search for C Ⅳ λλ1548, 1550 emission-lines from 81 Galactic supernova remnants was carried out using the data from the same instrument. In this search, C Ⅳ has been newly detected for seven targets, and then the origins for the four targets were confirmed. It has been found that some significant C...