Multiwavelength Observations of the Low-Metallicity Blue Compact Dwarf Galaxy SBS 0335−052

Abstract

New infrared and millimeter observations from Keck, Palomar, ISO, and OVRO and archival data from the NRAO^(**) VLA and IRAS are presented for the low-metallicity blue compact dwarf galaxy SBS 0335-052. Mid-infrared imaging shows this young star-forming system is compact (0farcs31; 80 pc) at 12.5 μm. The large Brγ equivalent width (235 Å) measured from integral field spectroscopy is indicative of a ~5 Myr starburst. The central source appears to be optically thin in emission, containing both a warm (~80 K) and a hot (~210 K) dust component, and the overall interstellar radiation field is quite intense, about 10,000 times the intensity in the solar neighborhood. CO emission is not detected, though the galaxy shows an extremely high global H I gas-to-dust mass ratio, high even for blue compact dwarfs. Finally, the galaxy's ratio of mid-infrared-to-optical and mid-to-near-infrared luminosities are quite high, whereas its far-infrared-to-radio and far-infrared-to-optical flux ratios are surprisingly similar to what is seen in normal star-forming galaxies. The relatively high bolometric infrared-to-radio ratio is more easily understood in the context of such a young system with negligible nonthermal radio continuum emission. These new lines of evidence may outline features common to primordial galaxies found at high redshift.