The dust content and radiation fields of sample of galaxies in the ELAIS-N1 field

Abstract

The Mid-IR colors (F8/F24) of galaxies together with their IR-UV luminosity correlations can be used to get some insight into the relative abundance of the different dust grain populations present in them. The ELAIS-N1 field contains thousands of galaxies which do not have optical spectra but have been observed in the Mid-IR by Spitzer and UV by GALEX, making it ideal for these studies. As part of this work we have selected a sample of galaxies from the ELAIS-N1 field which have photometric observations in the MIR and UV as well as photometric redshifts from the SDSS database. We follow the constraint that the redshifts are ≤ 0.1, thereby giving us a total of 309 galaxies. We find that the majority of the galaxies in the sample are PAH dominated due to their high MIR flux ratio. We also find a reasonable correlation between the Mid-IR and the UV luminosities out of which the Mid-IR emission from PAHs at 8 μm is marginally better correlated than the 24 μm VSG emission with the UV luminosities. However, if we divide the sample based on their F8/F24 ratios, which is also an indicator of metallicity, the MIR-UV correlation seems to increase with the F8/F24 ratio. But the MIR-UV correlations are not very different for the PAHs and the VSG population within the individual metallicity groups.