Spiral-like star-forming patterns in CALIFA early-type galaxies

Abstract

Based on a combined analysis of SDSS imaging and CALIFA integral field spectroscopy data, we report on the detection of faint (24 < µ r mag/ < 26) star-forming spiral-arm-like features in the periphery of three nearby early-type galaxies (ETGs). These features are of considerable interest because they document the still ongoing inside-out growth of some local ETGs and may add valuable observational insight into the origin and evolution of spiral structure in triaxial stellar systems. A characteristic property of the nebular component in the studied ETGs, classified i+, is a two-radial-zone structure, with the inner zone that displays faint (EW(Hα) 1 Å) low-ionization nuclear emission-line region (LINER) properties, and the outer one (3 Å < EW(Hα) < ∼ 20 Å) H-region characteristics. This spatial segregation of nebular emission in two physically distinct concentric zones calls for an examination of aperture effects in studies of type i+ ETGs with single-fiber spectroscopic data.

Galaxies hosting an active galactic nucleus: a view from the CALIFA survey

“…Nonetheless, other sources of ionization may populate these regions too. The most frequent ones are: (i) diffuse ionization ubiquitous associated with old-stellar populations (e.g., post-AGBs; Binette et al 1994;Singh et al 2013;Gomes et al 2016) as shown in the central region of the galaxy at the upper-right panel in Figure 2, IC 4566; and (ii) shock ionization, associated with galactic outflows at the resolution of our data (e.g. Bland-Hawthorn et al 2007).…”

SDSS-IV MaNGA: effects of morphology in the global and local star formation main sequences

“…García-Benito et al 2017;López Fernández et al 2018), showing that the quenching, although it becomes a global process, it has a local origin, and in general it gains strength from the center to the outer regions (González Delgado et al 2016;Belfiore et al 2017;López Fernández et al 2018;Sánchez et al 2018). Previous results have already shown the presence of retired/quenched areas in galaxies that are globally star-forming (e.g., Singh et al 2013), and the presence of star-forming areas in globally retired ones (Gomes et al 2016a). On top of that, we know that SFHs in SFGs are not all the same, presenting a decline toward lower values that depends on both the mass and the morphology (e.g.…”

“…Previous studies noticed about the nonneglible fraction of early-type galaxies with star formation (e.g. Thomas et al 2010;Gomes et al 2016a;Lacerna et al 2016, and more reference therein). This fraction is composed, among other groups, by (i) classical early-type galaxies that have recently suffered a rejuvenation induced by the capture of gas, and (ii) compact blue galaxies that probably acquired the early-type morphology in recent dissipation gas-rich mergers (see for a discussion, e.g.…”

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

“…Although early-type galaxies are frequently associated with the absence of star-forming regions, recent results indicate that a small fraction of them present H ii regions (e.g., Gomes et al 2016a). They could be either remnants of a former disk or the result of a rejuvenation due to the capture of gas-rich galaxies or in falling gas (Gomes et al 2016a). Table 1 H ii regions are located in late-type galaxies, with only ∼7% of the H ii regions hosted by E/S0 galaxies.…”