Mild evolution of the stellar metallicity gradients of disc galaxies

DOI: 
10.1051/0004-6361/201628915
Publication date: 
01/08/2017
Main author: 
Tissera, Patricia B.
IAA authors: 
Vilchez, José M.
Authors: 
Tissera, Patricia B.;Machado, Rubens E. G.;Vilchez, José M.;Pedrosa, Susana E.;Sanchez-Blazquez, Patricia;Varela, Silvio
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
604
Pages: 
A118
Abstract: 

Context. The metallicity gradients of the stellar populations in disc galaxies and their evolution store relevant information on the disc formation history and on those processes which could mix stars a posteriori, such as migration, bars and/or galaxy-galaxy interactions. <BR /> Aims: We aim to investigate the evolution of the metallicity gradients of the whole stellar populations in disc components of simulated galaxies in a cosmological context. <BR /> Methods: We analyse simulated disc galaxies selected from a cosmological hydrodynamical simulation that includes chemical evolution and a physically motivated supernova feedback capable of driving mass-loaded galactic winds. <BR /> Results: We detect a mild evolution with redshift in the metallicity slopes of - 0.02 ± 0.01 dex kpc<SUP>-1</SUP> from z 1. If the metallicity profiles are normalised by the effective radius of the stellar disc, the slopes show no clear evolution for z〈 1, with a median value of approximately - 0.23 dex r<SUB>eff</SUB><SUP>-1</SUP>. As a function of stellar mass, we find that metallicity gradients steepen for stellar masses smaller than 10<SUP>10.3</SUP>M<SUB>☉</SUB> while the trend reverses for higher stellar masses, in the redshift range z = [ 0,1 ]. Galaxies with small stellar masses have discs with larger r<SUB>eff</SUB> and flatter metallicity gradients than expected. We detect migration albeit weaker than in previous works. <BR /> Conclusions: Our stellar discs show a mild evolution of the stellar metallicity slopes up to z 1, which is well-matched by the evolution calculated archeologically from the abundance distributions of mono-age stellar populations at z 0. The dispersion in the relations allows for stronger individual evolutions. Overall, supernova feedback could explain the trends but an impact of migration can not be totally discarded. Galaxy-galaxy interactions or small satellite accretions can also contribute to modify the metallicity profiles in the outer parts. Disentangling the effects of these processes for individual galaxies is still a challenge in a cosmological context.

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028465510&doi=10.1051%2f0004-6361%2f201628915&partnerID=40&md5=a3837451bf2494b917ba7a1cb3bdadf4
ADS Bibcode: 
2017A&A...604A.118T
Keywords: 
galaxies: abundances;galaxies: formation;galaxies: evolution;galaxies: ISM;Astrophysics - Astrophysics of Galaxies;Astrophysics - Cosmology and Nongalactic Astrophysics