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  1. OA@INAF
  2. PRODOTTI RICERCA INAF
  3. 1 CONTRIBUTI IN RIVISTE (Journal articles)
  4. 1.01 Articoli in rivista
Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12386/28331
Title: The extended He II λ4686 emission in the extremely metal-poor galaxy SBS 0335 - 052E seen with MUSE
Authors: Kehrig, C.
Vílchez, J. M.
Guerrero, M. A.
Iglesias-Páramo, J.
HUNT, Leslie Kipp 
Duarte-Puertas, S.
Ramos-Larios, G.
Issue Date: 2018
Journal: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 
Number: 480
Issue: 1
First Page: 1081
Abstract: SBS 0335 - 052E, one of the most metal-poor (Z ∼ 3-4{{ per cent}} Z<SUB>☉</SUB>) He II-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 He II λ4686 emission from which we derived for the first time the total He II-ionizing energy budget of SBS 0335 - 052E. The nebular He II line is indicative of a quite hard ionizing spectrum with photon energies > 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 He II 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 Wolf-Rayet stars as the main responsible for the He II ionization. By comparing observations with current models, we found that the He II-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' initial mass function. This discrepancy between the metallicity of such stars and that of the H II regions in SBS 0335 - 052E is similar to results obtained by Kehrig et al. for the very metal-deficient He II-emitting galaxy IZw18. These results suggest that the He II 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.
URI: http://hdl.handle.net/20.500.12386/28331
URL: https://academic.oup.com/mnras/article-abstract/480/1/1081/5056186?redirectedFrom=fulltext
ISSN: 0035-8711
DOI: 10.1093/mnras/sty1920
Bibcode ADS: 2018MNRAS.480.1081K
Fulltext: open
Appears in Collections:1.01 Articoli in rivista

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