The star formation history of CALIFA galaxies: Radial structures

Abstract

We have studied the radial structure of the stellar mass surface density (µ * ) and stellar population age as a function of the total stellar mass and morphology for a sample of 107 galaxies from the CALIFA survey. We applied the fossil record method based on spectral synthesis techniques to recover the star formation history (SFH), resolved in space and time, in spheroidal and disk dominated galaxies with masses from 10 9 to 10 12 M . We derived the half-mass radius, and we found that galaxies are on average 15% more compact in mass than in light. The ratio of half-mass radius to half-light radius (HLR) shows a dual dependence with galaxy stellar mass; it decreases with increasing mass for disk galaxies, but is almost constant in spheroidal galaxies. In terms of integrated versus spatially resolved properties, we find that the galaxy-averaged stellar population age, stellar extinction, and µ * are well represented by their values at 1 HLR. Negative radial gradients of the stellar population ages are present in most of the galaxies, supporting an inside-out formation. The larger inner (≤1 HLR) age gradients occur in the most massive (10 11 M ) disk galaxies that have the most prominent bulges; shallower age gradients are obtained in spheroids of similar mass. Disk and spheroidal galaxies show negative µ * gradients that steepen with stellar mass. In spheroidal galaxies, µ * saturates at a critical value (∼7 × 10 2 M /pc 2 at 1 HLR) that is independent of the galaxy mass. Thus, all the massive spheroidal galaxies have similar local µ * at the same distance (in HLR units) from the nucleus. The SFH of the regions beyond 1 HLR are well correlated with their local µ * , and follow the same relation as the galaxy-averaged age and µ * ; this suggests that local stellar mass surface density preserves the SFH of disks. The SFH of bulges are, however, more fundamentally related to the total stellar mass, since the radial structure of the stellar age changes with galaxy mass even though all the spheroid dominated galaxies have similar radial structure in µ * . Thus, galaxy mass is a more fundamental property in spheroidal systems, while the local stellar mass surface density is more important in disks.

The CALIFA Survey: Exploring the Oxygen Abundance in the Local Universe

“…Recent results, based on the analysis of the star formation history of CALIFA data, found undisputed evidence of the inside-out growth of the stellar mass in galaxies [17], at least for galaxies more massive than 10 10 M . These results are also supported by the radial distribution of the stellar ages found for the same dataset [18]. However, the described characteristic slope for the abundance gradient, independent of many of the properties of the galaxies, was only recently proposed [41].…”

“…We found solid evidence that mass assembly in typical galaxies happens from inside-out [17]. The SFH and chemical enrichment of bulges and early-type galaxies are fundamentally related to the total stellar mass, while for disk galaxies, it is more related to the local stellar mass density [18,19]; negative age gradients indicate that the quenching is progressing outwards in massive galaxies [18], and age and metallicity gradients suggest that galaxy bars have not significantly altered the SFH of spirals [20]; finally, we explore the spatially-resolved stellar populations across the Hubble sequence [19] and how mergers influence the assembly of blue elliptical galaxies [21]. (ii) We explore the origin of the low intensity, LINER -like, ionized gas in galaxies.…”

H ii regions in the CALIFA survey: I. catalogue presentation

“…Pipe3D adopts FIT3D as the core fitting package (Sánchez et al 2016a), and the GSD156 simple stellar population library in the current implementation. This library that includes 156 templates: 39 stellar ages (from 1 Myr to 14.1 Gyr), and four metallicities (Z/Z =0.2, 0.4, 1, and 1.5), has been already used in many different previous publications (e.g., Pérez et al 2013;González Delgado et al 2014;Ibarra-Medel et al 2016;Méndez-Abreu et al 2019). Details of the fitting procedure, the adopted dust attenuation curve, and limitations of the processing of the stellar populations are given in Sánchez et al (2016a,b).…”

The Abundance Properties of Nearby Late-Type Galaxies. Ii. The Relation Between Abundance Distributions and Surface Brightness Profiles

“…The timescale of gas accretion is assumed to increase with radius. This results in an inside-out evolution of the disks of spiral galaxies (Matteucci & François 1989;Muñoz-Mateos et al 2011;González Delgado et al 2014). In this scenario the star formation history in the disk can be described by the expression…”