{"volume":924,"month":"01","date_updated":"2022-07-19T09:38:03Z","keyword":["Space and Planetary Science","Astronomy and Astrophysics"],"date_created":"2022-07-06T12:48:32Z","_id":"11511","title":"On the variation in stellar α-enhancements of star-forming galaxies in the EAGLE simulation","author":[{"first_name":"Andrea","last_name":"Gebek","full_name":"Gebek, Andrea"},{"first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720","full_name":"Matthee, Jorryt J","last_name":"Matthee","orcid":"0000-0003-2871-127X"}],"type":"journal_article","article_number":"73","year":"2022","publication_status":"published","oa":1,"oa_version":"Published Version","acknowledgement":"We thank our anonymous referee for the constructive feedback. We extend our gratitude to Maarten Baes, Simon Lilly, Rafael Ottersberg, Gabriele Pezzulli, Alvio Renzini, and Andrea Weibel for insightful discussions. A.G. gratefully acknowledges financial support from the Fund for Scientific Research Flanders (FWO-Vlaanderen, project G.0G04.16N). This work used the DiRAC Data Centric system at Durham University, operated by the ICC on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment was funded by BIS National E-infrastructure capital grant ST/K00042X/1, STFC capital grant ST/H008519/1, and STFC DiRAC Operations grant ST/K003267/1 and Durham University. DiRAC is part of the National E-Infrastructure.\r\n\r\nWe have benefited from the data analysis tool Topcat (Taylor 2013) and the programming language Python, including the numpy (van der Walt et al. 2011), matplotlib (Hunter 2007), and scipy (Virtanen et al. 2020) packages.","article_type":"original","intvolume":"       924","extern":"1","publication":"The Astrophysical Journal","external_id":{"arxiv":["2102.04561"]},"quality_controlled":"1","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2102.04561"}],"date_published":"2022-01-13T00:00:00Z","publication_identifier":{"issn":["0004-637X"],"eissn":["1538-4357"]},"status":"public","day":"13","citation":{"ama":"Gebek A, Matthee JJ. On the variation in stellar α-enhancements of star-forming galaxies in the EAGLE simulation. <i>The Astrophysical Journal</i>. 2022;924(2). doi:<a href=\"https://doi.org/10.3847/1538-4357/ac350b\">10.3847/1538-4357/ac350b</a>","ieee":"A. Gebek and J. J. Matthee, “On the variation in stellar α-enhancements of star-forming galaxies in the EAGLE simulation,” <i>The Astrophysical Journal</i>, vol. 924, no. 2. IOP Publishing, 2022.","chicago":"Gebek, Andrea, and Jorryt J Matthee. “On the Variation in Stellar α-Enhancements of Star-Forming Galaxies in the EAGLE Simulation.” <i>The Astrophysical Journal</i>. IOP Publishing, 2022. <a href=\"https://doi.org/10.3847/1538-4357/ac350b\">https://doi.org/10.3847/1538-4357/ac350b</a>.","short":"A. Gebek, J.J. Matthee, The Astrophysical Journal 924 (2022).","apa":"Gebek, A., &#38; Matthee, J. J. (2022). On the variation in stellar α-enhancements of star-forming galaxies in the EAGLE simulation. <i>The Astrophysical Journal</i>. IOP Publishing. <a href=\"https://doi.org/10.3847/1538-4357/ac350b\">https://doi.org/10.3847/1538-4357/ac350b</a>","mla":"Gebek, Andrea, and Jorryt J. Matthee. “On the Variation in Stellar α-Enhancements of Star-Forming Galaxies in the EAGLE Simulation.” <i>The Astrophysical Journal</i>, vol. 924, no. 2, 73, IOP Publishing, 2022, doi:<a href=\"https://doi.org/10.3847/1538-4357/ac350b\">10.3847/1538-4357/ac350b</a>.","ista":"Gebek A, Matthee JJ. 2022. On the variation in stellar α-enhancements of star-forming galaxies in the EAGLE simulation. The Astrophysical Journal. 924(2), 73."},"scopus_import":"1","doi":"10.3847/1538-4357/ac350b","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","issue":"2","language":[{"iso":"eng"}],"article_processing_charge":"No","abstract":[{"text":"The ratio of α-elements to iron in galaxies holds valuable information about the star formation history (SFH) since their enrichment occurs on different timescales. The fossil record of stars in galaxies has mostly been excavated for passive galaxies, since the light of star-forming galaxies is dominated by young stars, which have much weaker atmospheric absorption features. Here we use the largest reference cosmological simulation of the EAGLE project to investigate the origin of variations in stellar α-enhancement among star-forming galaxies at z = 0, and their impact on integrated spectra. The definition of α-enhancement in a composite stellar population is ambiguous. We elucidate two definitions—termed “mean” and “galactic” α-enhancement—in more detail. While a star-forming galaxy has a high “mean” α-enhancement when its stars formed rapidly, a galaxy with a large “galactic” α-enhancement generally had a delayed SFH. We find that absorption-line strengths of Mg and Fe correlate with variations in α-enhancement. These correlations are strongest for the “galactic” α-enhancement. However, we show that these are mostly caused by other effects that are cross-correlated with α-enhancement, such as variations in the light-weighted age. This severely complicates the retrieval of α-enhancements in star-forming galaxies. The ambiguity is not severe for passive galaxies, and we confirm that spectral variations in these galaxies are caused by measurable variations in α-enhancements. We suggest that this more complex coupling between α-enhancement and SFHs can guide the interpretation of new observations of star-forming galaxies.","lang":"eng"}],"publisher":"IOP Publishing"}