Infrared Photometric Study of Wolf-Rayet Galaxies

We collected observational data on 781 Wolf-Rayet (WR) galaxies from the literature to photometrically study their infrared properties measured by the 2MASS, WISE, IRAS, AKARI, and Herschel missions. It is found that in the 1-5 mu m range the radiations of WR galaxies are dominated by the free-free emissions from the stellar winds and the circumstellar dust from the late-type stars in the host galaxy. In the 5-22 mu m range, the radiation of WR galaxies is dominated by the free-free emissions and the synchrotron radiation from the central active galactic nucleus (AGN; but not always present). In the 22-140 mu m range, the radiations of WR galaxies are dominated by the free-free emissions and the star formation/starburst activities. In the 250-500 mu m range, the radiation of WR galaxies is dominated by the free-free emissions. In addition, the comparison with the non-WR galaxies is made. It is shown that some star formation WR galaxies have redder near-infrared colors than non-WR star-forming galaxies probably due to the gas emission in the near-infrared. In the 2-5 mu m region WR galaxies have redder colors due to the thermal emission from circumstellar dust of late-type stars and the enhanced gas emission. In the 5-22 mu m region, both WR galaxies and non-WR galaxies have similar behavior, indicative of having similar free-free emission as the dominant radiation. In the 25-140 mu m region, both types of galaxies also have similar behavior, indicative of having free-free emission from the stellar winds or the thermal radiation from the starburst/star formation as the dominant radiation.