Self-similarity in the chemical evolution of galaxies and the delay-time distribution of SNe Ia

¹ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: jwalcher@aip.de
² Max-Planck Institut für Extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany
³ Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
⁴ Max-Plank Institut für Astronomie, Königstuhl 17, 69917 Heidelberg, Germany
⁵ Instituto de Radiastronomia and Astrofisica (IRyA), Morelia, 58089 Michoacan, Mexico
⁶ Sorbonne Universités, UPMC-CNRS, UMR 7095, Institut d’Astrophysique de Paris, 75014 Paris, France
⁷ Instituto de Astronomia, Geofisica e Ciencias Atmosféricas, Universidade de São Paulo, Rua do Matao 1226, 05508-090 − São Paulo, Brasil
⁸ INAF−Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy

Received: 21 December 2015
Accepted: 19 July 2016

Abstract

Recent improvements in the age dating of stellar populations and single stars allow us to study the ages and abundance of stars and galaxies with unprecedented accuracy. We here compare the relation between age and α-element abundances for stars in the solar neighborhood to that of local, early-type galaxies. We find these two relations to be very similar. Both fall into two regimes with a shallow slope for ages younger than ~9 Gyr and a steeper slope for ages older than that value. This quantitative similarity seems surprising because of the different types of galaxies and scales involved. For the sample of early-type galaxies we also show that the data are inconsistent with literature delay-time distributions of either single- or double-Gaussian shape. The data are consistent with a power-law delay-time distribution. We thus confirm that the delay-time distribution inferred for the Milky Way from chemical evolution arguments must also apply to massive early-type galaxies. We also offer a tentative explanation for the seeming universality of the age-[α/Fe] relation: it is the manifestation of averaging different stellar populations with varying chemical evolution histories.