Star-forming galaxies with hot dust emission in the Sloan Digital Sky Survey discovered by the Wide-field Infrared Survey Explorer (WISE)

TL;DR

This study identifies star-forming galaxies with hot dust emission using WISE infrared data and SDSS spectra, revealing correlations with starburst activity and rarity of extremely red dust-emitting galaxies.

Contribution

It introduces a method to find hot dust emitting star-forming galaxies by combining SDSS emission-line data with WISE infrared colours, highlighting their properties and rarity.

Findings

Approximately 5000 SDSS galaxies are detected in WISE PRSC.

Redder W1-W2 correlates with higher Hbeta luminosity and equivalent width.

Galaxies with W1-W2>2 mag are very rare, with only four found.

Abstract

We present the results of a search for Sloan Digital Sky Survey (SDSS) emission-line galaxies with very red 3.4mum - 4.6mum (W1-W2) colours in the Wide-field Infrared Survey Explorer (WISE) Preliminary Release Source Catalogue (PRSC) aiming to find objects with hot dust emission. For this purpose we considered a sample of ~16000 galaxies with strong emission lines selected out of a total of ~900000 SDSS spectra and identified them with the PRSC sources. We find that ~5000 sources out of the ~16000 SDSS galaxies are present in the PRSC, including ~1000 galaxies with sufficiently strong [OIII]4363 emission lines to permit reliable determinations of the oxygen abundance. No correlation of W1-W2 with metallicity is found. On the other hand, there is clear evidence for a redder W1-W2 index in galaxies with higher Hbeta luminosity and higher Hbeta equivalent width, implying that strong UV radiation from young starbursts efficiently heats interstellar dust to high temperatures. However, galaxies with very red colours W1-W2>2 mag, similar to that in the local extreme star-forming galaxy SBS 0335-052E, are very rare. In addition to three previously known sources, which are not present in our sample, we found only four such galaxies.