The frequency of very young galaxies in the local Universe - II. The view from SDSS spectra
| Autor: | Gary A Mamon, Marina Trevisan, Trinh X Thuan, Anna Gallazzi, Romeel Davé |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
numerical [Methods]
Galáxias anãs 010308 nuclear & particles physics astro-ph.GA FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics evolution [Galaxies] Astrophysics - Astrophysics of Galaxies 01 natural sciences dwarf [Galaxies] statistics [Galaxies] Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Evolucao galatica 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Métodos numéricos 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics |
| Zdroj: | Mamon, G A, Trevisan, M, Thuan, T X, Gallazzi, A & Davé, R 2020, ' The frequency of very young galaxies in the local Universe-II. The view from SDSS spectra ', Monthly Notices of the Royal Astronomical Society, vol. 492, no. 2, pp. 1791-1811 . https://doi.org/10.1093/mnras/stz3556 Repositório Institucional da UFRGS Universidade Federal do Rio Grande do Sul (UFRGS) instacron:UFRGS |
| DOI: | 10.1093/mnras/stz3556 |
| Popis: | Only a handful of galaxies in the local Universe appear to be very young. We estimate the fraction of very young galaxies (VYGs), defined as those with more than half their stellar masses formed within the last Gyr. We fit non-parametric star formation histories (SFHs) to ~280 000 galaxy spectra from a flux- and volume-limited subsample of the Main Galaxy Sample (MGS) of the SDSS, which is also complete in mass-to-light ratio, thus properly accounting for passive galaxies of a given mass. The VYG fractions decrease with increasing galaxy stellar mass, from ~50% at $m = 10^8\,\rm M_\odot$ to ~0.1% at $m = 10^{11.5}\,\rm M_\odot$, with differences of up to 1 dex between the different spectral models used to estimate the SFH and on how we treat aperture effects. But old stellar populations may hide in our VYGs despite our conservative VYG sample built with galaxies that are globally bluer than within the region viewed by the SDSS fibre. The VYG fractions versus mass decrease more gradually compared to the Tweed et al. predictions using analytical and semi-analytical models of galaxy formation, but agree better with the SIMBA hydrodynamical simulation. These discrepancies highlight the usefulness of VYGs in constraining the strong uncertainties in both galaxy formation models and spectral modelling of galaxy SFHs. Given the lognormal cosmic SFH, these mean VYG fractions suggest that galaxies with $m > 10^8\,\rm M_\odot$ undergo at most 4 major starbursts on average. Published version, consolidated with Erratum on caption of Table A1 (the table is for all 404 931 galaxies in the Clean sample, not just those that are candidate VYGs according to at least one spectral model). New is in green and omitted is in strikeout-red |
| Databáze: | OpenAIRE |
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