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http://hdl.handle.net/20.500.12386/28204
Title: | Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time | Authors: | Zhang, Zhi-Yu ROMANO, Donatella Ivison, R. J. Papadopoulos, Padelis P. Matteucci, F. |
Issue Date: | 2018 | Journal: | NATURE | Number: | 558 | Issue: | 7709 | First Page: | 260 | Abstract: | All measurements of cosmic star formation must assume an initial distribution of stellar masses—the stellar initial mass function—in order to extrapolate from the star-formation rate measured for typically rare, massive stars (of more than eight solar masses) to the total star-formation rate across the full stellar mass spectrum<SUP>1</SUP>. The shape of the stellar initial mass function in various galaxy populations underpins our understanding of the formation and evolution of galaxies across cosmic time<SUP>2</SUP>. Classical determinations of the stellar initial mass function in local galaxies are traditionally made at ultraviolet, optical and near-infrared wavelengths, which cannot be probed in dust-obscured galaxies<SUP>2,3</SUP>, especially distant starbursts, whose apparent star-formation rates are hundreds to thousands of times higher than in the Milky Way, selected at submillimetre (rest-frame far-infrared) wavelengths<SUP>4,5</SUP>. The <SUP>13</SUP>C/<SUP>18</SUP>O isotope abundance ratio in the cold molecular gas—which can be probed via the rotational transitions of the <SUP>13</SUP>CO and C<SUP>18</SUP>O isotopologues—is a very sensitive index of the stellar initial mass function, with its determination immune to the pernicious effects of dust. Here we report observations of <SUP>13</SUP>CO and C<SUP>18</SUP>O emission for a sample of four dust-enshrouded starbursts at redshifts of approximately two to three, and find unambiguous evidence for a top-heavy stellar initial mass function in all of them. A low <SUP>13</SUP>CO/C<SUP>18</SUP>O ratio for all our targets—alongside a well tested, detailed chemical evolution model benchmarked on the Milky Way<SUP>6</SUP>—implies that there are considerably more massive stars in starburst events than in ordinary star-forming spiral galaxies. This can bring these extraordinary starbursts closer to the `main sequence' of star-forming galaxies<SUP>7</SUP>, although such main-sequence galaxies may not be immune to changes in initial stellar mass function, depending on their star-formation densities. | URI: | http://hdl.handle.net/20.500.12386/28204 | URL: | https://www.nature.com/articles/s41586-018-0196-x https://arxiv.org/pdf/1806.01280.pdf |
ISSN: | 0028-0836 | DOI: | 10.1038/s41586-018-0196-x | Bibcode ADS: | 2018Natur.558..260Z | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
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1806.01280.pdf | preprint | 1.27 MB | Adobe PDF | View/Open |
Natures41586-018-0196-x.pdf | [Administrators only] | 2.93 MB | Adobe PDF |
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