Interstellar gas toward the Magellanic supernova remnants

Abstract

We present new CO observations toward 25 supernova remnants (SNRs) residing with the Large Magellanic Cloud, including the TeV γ-ray sources N132D and 30 Doradus C. Our observations revealed that∼90% of the SNRs were detected by 12CO(J = 1–0) line emission with a 3σ level or higher. At least ten of them were shown to have CO clouds that have a good spatial correspondence with thermal/non-thermal X-rays; this indicates that shock-cloud interactions may have occurred. The molecular gases associated with N132D showed a high intensity ratio of 12CO J = 3–2 / 1–0 > 0.8, indicates that shock-heating occurred. We also found five molecular clouds and three Hi clouds associated with 30 Doradus C, which showed either complimentary or similar distributions to the non-thermal X-ray filaments in a 10 pc scale. The interstellar proton density of 30 Doradus C was estimated to be ∼ 60 cm−3, which corresponded to the total energy of the cosmic-ray protons being at least∼1.2×1050 erg.