The chemical evolution of galaxies within the IGIMF theory: the [alpha/Fe] ratios and downsizing

Abstract

The chemical evolution of galaxies is investigated within the framework of the star formation rate (SFR) dependent integrated galactic initial mass function (IGIMF). We study how the global chemical evolution of a galaxy and in particular how [alpha/Fe] abundance ratios are affected by the predicted steepening of the IGIMF with decreasing SFR. We use analytical and semi-analytical calculations to evaluate the mass-weighted and luminosity-weighted [alpha/Fe] ratios in early-type galaxies of different masses. The models with the variable IGIMF produce a [alpha/Fe] vs. velocity dispersion relation which has the same slope as the observations of massive galaxies, irrespective of the model parameters, provided that the star formation duration inversely correlates with the mass of the galaxy (downsizing). These models also produce steeper [alpha/Fe] vs. sigma relations in low-mass early-type galaxies and this trend is consistent with the observations. Constant IMF models are able to reproduce the [alpha/Fe] ratios in large elliptical galaxies as well, but they do not predict this change of slope for small galaxies. In order to obtain the best fit between our results and the observations, the downsizing effect (i.e. the shorter duration of the star formation in larger galaxies) must be milder than previously thought.

13 pages, 18 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (8)

• A Possible Origin of the Mass-Metallicity Relation of Galaxies
• Converting H$\alpha$ Luminosities into Star Formation Rates
• On the fraction of intermediate-mass close binaries that explode as type-Ia supernovae
• The effect of differential galactic winds on the chemical evolution of galaxies
• Kinematics and Stellar Populations of Low-Luminosity Early-Type Galaxies in the Abell 496 Cluster
• Supermassive black holes, star formation and downsizing of elliptical galaxies
• Cosmic Supernova Rates and the Hubble Sequence
• Bimodality in low luminosity E and S0 galaxies

Cited by in corpus (54)

• Origin of the Heaviest Elements: the Rapid Neutron-Capture Process
• The stellar and sub-stellar IMF of simple and composite populations
• Constraints on star-formation driven galaxy winds from the mass-metallicity relation at z=0
• Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation
• The impact of the metallicity and star formation rate on the time-dependent galaxy-wide stellar initial mass function
• The evolution of CNO isotopes: a new window on cosmic star-formation history and the stellar IMF in the age of ALMA
• The mmax-Mecl relation, the IMF and IGIMF: probabilistically sampled functions?
• The galaxy-wide IMF of dwarf late-type to massive early-type galaxies
• Chemical evolution of local galaxies in a hierarchical model
• The dust-to-stellar mass ratio as a valuable tool to probe the evolution of local and distant star forming galaxies
• Chemo-Archaeological Downsizing in a Hierarchical Universe: Impact of a Top Heavy IGIMF
• Variations of the initial mass function in semi-analytical models: implications for the mass assembly and the chemical enrichment of galaxies in the GAEA model
• Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations
• Dwarf elliptical galaxies as ancient tidal dwarf galaxies
• The fundamental gas depletion and stellar-mass buildup times of star forming galaxies
• The most massive stars in very young star clusters with a limited mass: Evidence favours significant self-regulation in the star formation processes
• Chemo-dynamical evolution of tidal dwarf galaxies. I. Method and IMF dependence
• The Effect of Ram-Pressure Stripping on Dwarf Galaxies
• Top-heavy integrated galactic stellar initial mass functions (IGIMFs) in starbursts
• Chemo-dynamical evolution of tidal dwarf galaxies. II. The long-term evolution and influence of a tidal field
• The formation of UCDs and massive GCs: Quasar-like objects for testing for a variable stellar initial mass function (IMF)
• Chemical evolution of ultra-faint dwarf galaxies in the self-consistently calculated IGIMF theory
• The chemical evolution of galaxies with a variable IGIMF
• The galactocentric radius dependent upper mass limit of young star clusters: stochastic star formation ruled out
• Variations in Integrated Galactic Initial Mass Functions due to Sampling Method and Cluster Mass Function
• Chemical evolution of elliptical galaxies with a variable IMF -- A publicly available code
• Effects of the integrated galactic IMF on the chemical evolution of the solar neighbourhood
• The Star Formation History and Dynamics of the Ultra-diffuse Galaxy Dragonfly 44 in MOND and MOG
• The IGIMF and other IMFs in dSphs: the case of Sagittarius
• The effects of the IMF on the chemical evolution of elliptical galaxies
• The formation of early-type galaxies through monolithic collapse of gas clouds in Milgromian gravity
• On the effects of the Initial Mass Function on Galactic chemical enrichment
• Was the Milky Way a chain galaxy? Using the IGIMF theory to constrain the thin-disk star formation history and mass
• The effect of the environment-dependent stellar initial mass function on the photometric properties of star-forming galaxies
• The Abundance Pattern in the Hot ISM of NGC 4472: Insights and Anomalies
• The influence of a top-heavy integrated galactic IMF and dust on the chemical evolution of high-redshift starbursts
• Is the IMF in ellipticals bottom-heavy? Clues from their chemical abundances
• A possible solution to the [alpha/Fe]-sigma problem in early type galaxies within a hierarchical galaxy formation model
• The [alpha/Fe] ratios of very metal-poor stars within the IGIMF theory
• Chemo-dynamical simulations of dwarf galaxy evolution
• The Impact of Early Massive Galaxy Formation on the Cosmic Microwave Background
• Chemical evolution of ultra-faint dwarf galaxies: testing the IGIMF
• Stellar population synthesis models with a physically varying IMF
• Simple interpolation functions for the galaxy-wide stellar initial mass function and its effects in early-type galaxies
• Distribution of star formation rates during the rapid assembly of NGC 1399 as deduced from its globular cluster system
• Lessons from the Local Group (and beyond) on dark matter
• Refueled and shielded - The early evolution of Tidal Dwarf Galaxies
• The stellar populations in the low luminosity, early-type galaxy NGC59
• On the primordial specific frequency of globular clusters in dwarf and giant elliptical galaxies
• The star formation timescale of elliptical galaxies -- Fitting [Mg/Fe] and total metallicity simultaneously
• The [alpha/Fe] Ratios in Dwarf Galaxies: Evidence for a Non-universal Stellar Initial Mass Function?
• The MOND Depth Index and Dynamical Maturity Clock: Toward a Universal Classification of Galaxies and Star Clusters
• Chemical Enrichment of Isolated Relic Galaxy Mrk1216
• Downsizing revised: Star formation timescales for elliptical galaxies with an environment-dependent IMF and number of SNIa