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arXiv · 1106.4844

WISE Discovery of Low Metallicity Blue Compact Dwarf Galaxies

Roger L. Griffith·Chao-Wei Tsai·Daniel Stern·Andrew Blain·Peter R. M. Eisenhardt·Fiona Harrison·Thomas H. Jarrett·Kristin Madsen·Spencer A. Stanford·Edward L. Wright·Jingwen Wu·Yanling Wu·Lin Yan
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Abstract

We report two new low metallicity blue compact dwarf galaxies (BCDs), WISEP J080103.93+264053.9 (hereafter W0801+26) and WISEP J170233.53+180306.4 (hereafter W1702+18), discovered using the Wide-field Infrared Survey Explorer (WISE). We identified these two BCDs from their extremely red colors at mid-infrared wavelengths, and obtained follow-up optical spectroscopy using the Low Resolution Imaging Spectrometer on Keck I. The mid-infrared properties of these two sources are similar to the well studied, extremely low metallicity galaxy SBS 0335-052E. We determine metallicities of 12 + log(O/H) = 7.75 and 7.63 for W0801+26 and W1702+18, respectively, placing them amongst a very small group of very metal deficient galaxies (Z < 1/10 Zsun). Their > 300 Angstrom Hbeta equivalent widths, similar to SBS 0335-052E, imply the existence of young (< 5 Myr) star forming regions. We measure star formation rates of 2.6 and 10.9 Msun/yr for W0801+26 and W1702+18, respectively. These BCDs, showing recent star formation activity in extremely low metallicity environments, provide new laboratories for studying star formation in extreme conditions and are low-redshift analogs of the first generation of galaxies to form in the universe. Using the all-sky WISE survey, we discuss a new method to identify similar star forming, low metallicity BCDs.

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Roger L. Griffith, Chao-Wei Tsai, Daniel Stern, Andrew Blain, Peter R. M. Eisenhardt, Fiona Harrison, Thomas H. Jarrett, Kristin Madsen, Spencer A. Stanford, Edward L. Wright, Jingwen Wu, Yanling Wu, Lin Yan. 2011-06-23. WISE Discovery of Low Metallicity Blue Compact Dwarf Galaxies. https://doi.org/10.1088/2041-8205%2F736%2F1%2Fl22

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