Star Formation in the Local Universe from the CALIFA Sample. II. Activation and Quenching Mechanisms in Bulges, Bars, and Disks

Abstract

We estimate the current extinction-corrected Hα star formation rate (SFR) of the different morphological components that shape galaxies (bulges, bars, and disks). We use a multicomponent photometric decomposition based on Sloan Digital Sky Survey imaging to Calar Alto Legacy Integral Field Area Integral Field Spectroscopy (IFS) datacubes for a sample of 219 galaxies. This analysis reveals an enhancement of the central SFR and specific SFR (sSFR=SFR/M å ) in barred galaxies. Along the main sequence, we find that more massive galaxies in total have undergone efficient suppression (quenching) of their star formation, in agreement with many studies. We discover that more massive disks have had their star formation quenched as well. We evaluate which mechanisms might be responsible for this quenching process. The presence of type 2 AGNs plays a role at damping the sSFR in bulges and less efficiently in disks. Also, the decrease in the sSFR of the disk component becomes more noticeable for stellar masses around  M 10 ; 10.5 for bulges, it is already present at~ M 10 9.5 . The analysis of the line-of-sight stellar velocity dispersions (σ) for the bulge component and of the corresponding Faber-Jackson relation shows that AGNs tend to have slightly higher σ values than star-forming galaxies for the same mass. Finally, the impact of environment is evaluated by means of the projected galaxy density, Σ 5 . We find that the SFR of both bulges and disks decreases in intermediate-to high-density environments. This work reflects the potential of combining IFS data with 2D multicomponent decompositions to shed light on the processes that regulate the SFR.

SDSS IV MaNGA: Dependence of Global and Spatially Resolved SFR–M∗ Relations on Galaxy Properties

“…When accounting for all non-H II mechanisms (the rightmost column), median f non-H II is no higher than 20% (mostly below 10%) for disks across all stellar mass bins, and increases to several tens of percent in bulges when log(M * /M e ) exceeding 10. The result is consistent with the study based on a 2D spectral decomposition of the bulge and disk component (Catalán-Torrecilla et al 2017). The high f non-H II of the bulge is presumably due to the fact that the non-H II sources (e.g., AGNs, evolved stars, and shocks) are naturally found most often in this old central component.…”

“…On the other hand, the quiescent population, primarily composed of bulge-dominated galaxies (e.g., Wuyts et al 2011), has a much lower specific star formation rate (sSFR≡SFR/M * ) with respect to the main sequence. Several studies have suggested that the mainsequence relation flattens at the high-mass end, possibly due to the growth of the bulge, which lowers the global sSFR of a galaxy (Noeske et al 2007;Abramson et al 2014;Whitaker et al 2015;Catalán-Torrecilla et al 2017).…”

Stellar age gradients and inside-out star formation quenching in galaxy bulges

“…Indeed, whereas in the local universe star formation (SF) is almost omnipresent in low-M ,B , low-Σ ,B bulges, it is steeply vanishing above a characteristic mass-density threshold log(M, Σ) c (10,9), as documented through multi-band photometry (e.g., Peng et al 2010;Omand et al 2014), single-aperture spectroscopy (e.g., Kauffmann et al 2003;Brinchmann et al 2004) Article number, page 1 of 7 arXiv:2001.05738v1 [astro-ph.GA] 16 Jan 2020 A&A proofs: manuscript no. age_gradients_15Jan20 and, more recently, spatially resolved integral field spectroscopy (IFS; e.g., Fang et al 2013;Catalán-Torrecilla et al 2017;Ellison et al 2018;Woo & Ellison 2019, BP18). For instance, Zibetti et al (2017) report from an analysis of stellar indices for 394 galaxies from the CALIFA IFS survey (Sánchez et al 2012) a bi-variate distribution of galaxy stellar populations on the Σ vs. luminosity-weighted age t /yr L plane, with old (log t L 10) quiescent E&S0 galaxies populating a high-density peak (log(Σ ) ≥ 8.3), whereas younger (log t L ≤ 9.5) LTGs being confined to log(Σ ) ≤ 8.…”

“…These include, e.g., i) the analysis of radial specific SFR (sSFR) profiles, obtained from Hα and EW(Hα) determinations (e.g. Catalán-Torrecilla et al 2017;Belfiore et al 2018), age-dating of stellar populations via ii) broad-band colors (e.g., Peletier & Balcells 1996;de Jong 1996;Peletier & de Grijs 1998;Muñoz-Mateos et al 2007) or iii) Lick indices (e.g. Thomas & Davies 2006;Morelli et al 2016), and iv) full spectral synthesis of IFS data (e.g.…”

Spectro-photometric decomposition of galaxy structural components

“…This work represents the extension of their previous work using long-slit spectra (Johnston et al 2012(Johnston et al , 2014 to the IFS case. Other spectro-photometric methods, including the possibly different kinematic distribution of the galaxy components, have also been developed (Coccato et al 2011;Tabor et al 2017;Catalán-Torrecilla et al 2017;Coccato et al 2018).…”