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Bruzzese, S.M. and Thilker, David A. and Meurer, G.R. and Bianchi, Luciana and Watts, A.B. and Ferguson, A.M.N. and Gil de Paz, Armando and Madore, B. and Martin, D. Christopher and Rich, R. Michael (2020) The initial mass function in the extended ultraviolet disc of M83. Monthly notices of the Royal Astronomical Society, 491 (2). pp. 2366-2390. ISSN 0035-8711
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Official URL: http://dx.doi.org/10.1093/mnras/stz3151
Abstract
Using Hubble Space Telescope ACS/WFC data we present the photometry and spatial distribution of resolved stellar populations of four fields within the extended ultraviolet disc (XUV disc) of M83. These observations showa clumpy distribution of main-sequence stars and a mostly smooth distribution of red giant branch stars. We constrain the upper end of the initial mass function (IMF) in the outer disc using the detected population of main-sequence stars and an assumed constant star formation rate (SFR) over the last 300 Myr. By comparing the observed main-sequence luminosity function to simulations, we determine the best-fitting IMF to have a power-law slope α=-2.35 +/- 0.3 and an upper mass limit M_(u) = 25_(-3)^(+17) Mͼ. This IMF is consistent with the observed Hα emission, which we use to provide additional constraints on the IMF. We explore the influence of deviations from the constant SFR assumption, finding that our IMF conclusions are robust against all but strong recent variations in SFR, but these are excluded by causality arguments. These results, along with our similar studies of other nearby galaxies, indicate that some XUV discs are deficient in high-mass stars compared to a Kroupa IMF. There are over one hundred galaxies within 5 Mpc, many already observed with HST, thus allowing a more comprehensive investigation of the IMF, and how it varies, using the techniques developed here.
Item Type: | Article |
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Additional Information: | © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We thank the anonymous referee, and the MNRAS editors, for comments which improved the quality of this paper. This study is based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA Contract NAS 5-26555. These observations are associated with Program 10608 (PI: D. Thilker). Support for Program 10608 was provided by NASA through a grant from the Space Telescope Science Institute. This study is based in part on observations made with the Galaxy Evolution Explorer (GALEX). GALEX is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASAs support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology. |
Uncontrolled Keywords: | Star-formation histories; Neutral gas galaxies; H-II regions; Diffuse ionized-gas; SDSS-IV manga; Nearby galaxies; Spiral galaxies; Stellar populations; Systematic variation; Evolutionary tracks |
Subjects: | Sciences > Physics > Astrophysics |
ID Code: | 59929 |
Deposited On: | 15 Apr 2020 08:51 |
Last Modified: | 15 Apr 2020 11:50 |
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