Supernova remnant W49B and its environment

Abstract

We study gamma-ray supernova remnant (SNR) W49B and its environment using recent radio and infrared data. Spitzer Infrared Spectrograph low resolution data of W49B shows shocked excitation lines of H2(0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H2gas is composed of two components with temperatures of 260 K and 1060 K, respectively. Various spectral lines from atomic and ionic particles are detected toward W49B. We suggest that the ionic phase has an electron density of 500 cm-3and a temperature of 104K by the spectral line diagnoses. The mid- and far-infrared data from MSX, Spitzer, and Herschel reveal a 151 ± 20 K hot dust component with a mass of 7.5 ± 6.6 × 10-4M and a 45 ± 4 K warm dust component with a mass of 6.4 ± 3.2 M . The hot dust is likely from materials swept up by the shock of W49B. The warm dust may possibly originate from the evaporation of clouds interacting with W49B. We build the H I absorption spectra of W49B and four nearby H II regions (W49A, G42.90+0.58, G42.43-0.26, and G43.19-0.53) and study the relation between W49B and the surrounding molecular clouds by employing the 2.12 μm infrared and CO data. We therefore obtain a kinematic distance of 10 kpc for W49B and suggest that the remnant is likely associated with the CO cloud at about 40 km s-1.