Impact of metallicity and star formation rate on the time-dependent, galaxy-wide stellar initial mass function

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F18%3A10388468" target="_blank" >RIV/00216208:11320/18:10388468 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1051/0004-6361/201833055" target="_blank" >https://doi.org/10.1051/0004-6361/201833055</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/201833055" target="_blank" >10.1051/0004-6361/201833055</a>

Result language

angličtina

Original language name

Impact of metallicity and star formation rate on the time-dependent, galaxy-wide stellar initial mass function

Original language description

The stellar initial mass function (IMF) is commonly assumed to be an invariant probability density distribution function of initial stellar masses. These initial stellar masses are generally represented by the canonical IMF, which is defined as the result of one star formation event in an embedded cluster. As a consequence, the galaxy-wide IMF (gwIMF) should also be invariant and of the same form as the canonical IMF, gwIMF is defined as the sum of the IMFs of all star-forming regions in which embedded clusters form and spawn the galactic field population of the galaxy. Recent observational and theoretical results challenge the hypothesis that the gwIMF is invariant. In order to study the possible reasons for this variation, it is useful to relate the observed IMF to the gwIMF. Starting with the IMF determined in resolved star clusters, we apply the IGIMF-theory to calculate a comprehensive grid of gwIMF models for metallicities, [Fe = H] is an element of (-3, 1), and galaxy-wide star formation rates (SFRs), SFR is an element of (10(-5), 10(5)) M-circle dot yr(-1). For a galaxy with metallicity [Fe/H] &lt; 0 and SFR &gt; 1 M-circle dot yr(-1), which is a common condition in the early Universe, we find that the gwIMF is both bottom light (relatively fewer low-mass stars) and top heavy (more massive stars), when compared to the canonical IMF. For a SFR &lt; 1 M-circle dot yr(-1) the gwIMF becomes top light regardless of the metallicity. For metallicities [Fe = H] &gt; 0 the gwIMF can become bottom heavy regardless of the SFR. The IGIMF models predict that massive elliptical galaxies should have formed with a gwIMF that is top heavy within the first few hundred Myr of the life of the galaxy and that it evolves into a bottom heavy gwIMF in the metal-enriched galactic centre. Using the gwIMF grids, we study the SFR H ff relation and its dependency on metallicity and the SFR. We also study the correction factors to the Kennicutt SFRK H ff relation and provide new fitting functions. Late-type dwarf galaxies show significantly higher SFRs with respect to Kennicutt SFRs, while star-forming massive galaxies have significantly lower SFRs than hitherto thought. This has implications for gas-consumption timescales and for the main sequence of galaxies. We explicitly discuss Leo P and ultra-faint dwarf galaxies.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2018

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy &amp; Astrophysics [online]

ISSN

1432-0746

e-ISSN

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Volume of the periodical

620

Issue of the periodical within the volume

listopad

Country of publishing house

FR - FRANCE

Number of pages

15

Pages from-to

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UT code for WoS article

000451249600007

EID of the result in the Scopus database

2-s2.0-85057747992