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Constraining the LyC escape fraction from LEGUS star clusters with SIGNALS H ii region observations: a pilot study of NGC 628

The ionizing radiation of young and massive stars is a crucial form of stellar feedback. Most ionizing (Lyman-continuum; LyC, λ < 912Å) photons are absorbed close to the stars that produce them, forming compact H ii regions, but some escape into the wider galaxy. Quantifying the fraction of LyC...

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Main Authors: Teh, Jia Wei (Author) , Grasha, Kathryn (Author) , Krumholz, Mark R (Author) , Battisti, Andrew J (Author) , Calzetti, Daniela (Author) , Rousseau-Nepton, Laurie (Author) , Rhea, Carter (Author) , Adamo, Angela (Author) , Kennicutt, Robert C (Author) , Grebel, Eva K. (Author) , Cook, David O (Author) , Combes, Francoise (Author) , Messa, Matteo (Author) , Linden, Sean T (Author) , Klessen, Ralf S. (Author) , Vilchez, José M (Author) , Fumagalli, Michele (Author) , McLeod, Anna (Author) , Smith, Linda J (Author) , Chemin, Laurent (Author) , Wang, Junfeng (Author) , Sabbi, Elena (Author) , Sacchi, Elena (Author) , Petric, Andreea (Author) , Bruna, Lorenza Della (Author) , Boselli, Alessandro (Author)
Format: Article (Journal)
Language:English
Published: September 2023
In: Monthly notices of the Royal Astronomical Society
Year: 2023, Volume: 524, Issue: 1, Pages: 1191-1210
ISSN:1365-2966
DOI:10.1093/mnras/stad1780
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1093/mnras/stad1780
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Author Notes:Jia Wei Teh, Kathryn Grasha, Mark R Krumholz, Andrew J Battisti, Daniela Calzetti, Laurie Rousseau-Nepton, Carter Rhea, Angela Adamo, Robert C Kennicutt, Eva K Grebel, David O Cook, Francoise Combes, Matteo Messa, Sean T Linden, Ralf S Klessen, José M Vilchez, Michele Fumagalli, Anna McLeod, Linda J Smith, Laurent Chemin, Junfeng Wang, Elena Sabbi, Elena Sacchi, Andreea Petric, Lorenza Della Bruna and Alessandro Boselli
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Summary:The ionizing radiation of young and massive stars is a crucial form of stellar feedback. Most ionizing (Lyman-continuum; LyC, λ < 912Å) photons are absorbed close to the stars that produce them, forming compact H ii regions, but some escape into the wider galaxy. Quantifying the fraction of LyC photons that escape is an open problem. In this work, we present a seminovel method to estimate the escape fraction by combining broadband photometry of star clusters from the Legacy ExtraGalactic UV Survey (LEGUS) with H ii regions observed by the Star formation, Ionized gas, and Nebular Abundances Legacy Survey (SIGNALS) in the nearby spiral galaxy NGC 628. We first assess the completeness of the combined catalogue, and find that 49 per cent of H ii regions lack corresponding star clusters as a result of a difference in the sensitivities of the LEGUS and SIGNALS surveys. For H ii regions that do have matching clusters, we infer the escape fraction from the difference between the ionizing power required to produce the observed H ii luminosity and the predicted ionizing photon output of their host star clusters; the latter is computed using a combination of LEGUS photometric observations and a stochastic stellar population synthesis code slug (Stochastically Lighting Up Galaxies). Overall, we find an escape fraction of fesc=0.09+0.06−0.06 across our sample of 42 H ii regions; in particular, we find H ii regions with high fesc are predominantly regions with low Hα-luminosity. We also report possible correlation between fesc and the emission lines [OII]/[NII] and [OII]/Hβ⁠.
Item Description:Veröffentlicht: 14. Juni 2023
Gesehen am 12.10.2023
Physical Description:Online Resource
ISSN:1365-2966
DOI:10.1093/mnras/stad1780

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