Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS0335-052 - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS0335-052 - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We present high-resolution radio continuum observations of the nascentstarburst in the metal-poor galaxy SBS 0335-052. These radio data were takenwith the Very Large Array and include observations at 0.7cm, 1.3cm, 2cm, 3.6cm,and 6cm. These observations enable us to probe the thermal radio nebulaeassociated with the extremely young star-forming regions in this galaxy. Twodiscrete and luminous star-forming regions are detected in the south of thegalaxy that appear to be associated with massive star clusters previouslyidentified at optical wavelengths. However, the remaining optically-identifiedmassive star clusters are not clearly associated with radio emission eitherthermal or non-thermal down to the sensitivity limits of these radio data. Thespectral energy distributions of the two radio-detected clusters are consistentwith being purely thermal, and the entire region has an inferred ionizing fluxof ~1.2 x 10^ 53 s^-1, which is equivalent to ~12,000 -typical- O-type starstype O7.5 V. The observations presented here have resolved out a significantcontribution from diffuse non-thermal emission detected previously, implying aprevious episode of significant star formation. The current star formation rateSFR for this southern region alone is ~1.3 M sun yr^-1, or ~ 23M sun yr^-1kpc^-2. This SFR derived from thermal radio emission also suggests thatprevious optical recombination line studies are not detecting a significantfraction of the current star formation in SBS 0335-052. From model fits to theradio spectral energy distribution, we infer a global mean density in the twoyoungest clusters of n e > 10^3-10^4 cm^-3. In addition, a comparison betweenthe compact and diffuse radio emission indicates that up to ~50% of theionizing flux could be leaking out of the compact HII regions.



Author: K. E. Johnson, L. K. Hunt, A.E. Reines

Source: https://arxiv.org/



DOWNLOAD PDF




Related documents