The extended HeIIλ4686 emission in the extremely metal-poor galaxy SBS 0335-052E seen with MUSE<SUP>★</SUP>

DOI: 
10.1093/mnras/sty1920
Publication date: 
01/07/2018
Main author: 
Kehrig, C.
IAA authors: 
Kehrig, C.;Vílchez, J. M.;Guerrero, M. A.;Iglesias-Páramo, J.;Puertas, S. Duarte
Authors: 
Kehrig, C.;Vílchez, J. M.;Guerrero, M. A.;Iglesias-Páramo, J.;Hunt, L. K.;Puertas, S. Duarte;Ramos-Larios, G.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Pages: 
1081-1095
Abstract: 
SBS 0335-052E, one of the most metal-poor (Z ̃ 3-4% Z<SUB>☉</SUB>) HeII-emitter starbursts known in the nearby universe, is studied using optical VLT/MUSE spectroscopic and Chandra X-ray observations. We spatially resolved the spectral map of the nebular HeIIλ4686 emission from which we derived for the first time the total HeII-ionizing energy budget of SBS 0335-052E. The nebular HeII line is indicative of a quite hard ionizing spectrum with photon energies &gt; 4 Ryd, and is observed to be more common at high-z than locally. Our study rules out a significant contribution from X-ray sources and shocks to the HeII photoionization budget, indicating that the He<SUP>+</SUP> excitation is mainly due to hot stellar continua. We discovered a new WR knot, but we also discard single WR stars as the main responsible for the HeII ionization. By comparing observations with current models, we found that the HeII-ionization budget of SBS 0335-052E can only be produced by either single, rotating metal-free stars or a binary population with Z ̃ 10<SUP>-5</SUP> and a 'top-heavy' IMF. This discrepancy between the metallicity of such stars and that of the HII regions in SBS 0335-052E is similar to results obtained by Kehrig et al. (2015) for the very metal-deficient HeII-emitting galaxy IZw18. These results suggest that the HeII ionization is still beyond the capabilities of state-of-the-art models. Extremely metal-poor, high-ionizing starbursts in the local universe, like SBS 0335-052E, provide unique laboratories for exploring in detail the extreme conditions likely prevailing in the reionization era.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2018MNRAS.480.1081K/abstract
ADS Bibcode: 
2018MNRAS.480.1081K
Keywords: 
galaxies: individual: SBS 0335-052E;galaxies: starburst;galaxies: dwarf;galaxies: ISM;galaxies: stellar content