Properties of ionized outflows in MaNGA DR2 galaxies

Abstract

We present the results from a systematic search and characterization of ionized outflows in nearby galaxies using the data from the second Data Release of the MaNGA Survey (DR2; > 2700 galaxies, z 0.015). Using the spatially-resolved spectral information provided by the MANGA data, we have identified ∼ 5200 Hα-emitting regions across the galaxies and searched for signatures of ionized outflows. We find evidence for ionized outflows in 105 regions from 103 galaxies, roughly 7% of all the Hα-emitting galaxies identified in this work. Most of the outflows are nuclear, with only two cases detected in off-nuclear regions. Our analysis allows us to study ionized outflows in individual regions with SF Rs down to ∼ 0.01 M yr −1 , extending the ranges probed by previous works. The kinematics of the outflowing gas are strongly linked to the type of ionization mechanism: regions characterized by LIER (Low-Ionization Emission Region) emission host the outflows with more extreme kinematics (F W HM broad ∼ 900 km/s), followed by those originated in AGN (550 km/s), 'Intermediate' (450 km/s) and SF (350 km/s) regions. Moreover, in most of the outflows we find evidence for gas ionized by shocks. We find a trend for higher outflow kinematics towards larger stellar masses of the host galaxies but no significant variation as a function of star formation properties within the SFR regime we probe (∼ 0.01 − 10 M yr −1 ). Our results also show that the fraction of outflowing gas that can escape from galaxies decreases towards higher dynamical masses, contributing to the preservation of the mass-metallicity relation by regulating the amount of metals in galaxies. Finally, assuming that the extensions of the outflows are significantly larger than the individual star-forming regions, as found in previous works, our results also support the presence of star formation within ionized outflows, as recently reported by Maiolino et al. (2017) and Gallagher et al. (2019).

The ALPINE-ALMA [C II] survey: Star-formation-driven outflows and circumgalactic enrichment in the early Universe

“…10 we show a comparison of our results with a compilation of local starbursts (Heckman et al 2015) and the best-fitting relations of local AGNs and normal star-forming galaxies from Fluetsch et al (2019) in the log(Ṁ out )-log(SFR) diagram. We find that our [C II] observations yield mass-loading factors, η =Ṁ out SFR , lower than (or consistent with) unity (η atom ∼ 0.3 − 0.9), in analogy with what is found in local star-forming galaxies (see e.g., García-Burillo et al 2015;Cicone et al 2016;Fluetsch et al 2019;Rodríguez del Pino et al 2019; see the orange line). Assuming corrections for the multi-phase outflowing gas contribution (using the calibration discussed above; see blue dashed line in Fig.…”

Enhanced UV radiation and dense clumps in the molecular outflow of Mrk 231

“…the spheroidal component of galaxies. Observational confirmations of this new mode of star formation have been presented recently (Maiolino et al 2017;Gallagher et al 2019;Rodríguez del Pino et al 2019). Within the context of our findings, young massive stars formed inside the outflow would provide a much stronger (internal) UV radiation field with respect to the illumination form stars in the disk or even from the AGN.…”

Stars made in outflows may populate the stellar halo of the Milky Way

“…Similarly, Gallagher et al (2019) have used the integral field spectroscopic data from MaNGA-SDSS4 to show that prominent star formation is occurring inside 30% of the galactic outflows in their sample. They also find that star formation inside outflows accounts for 5 − 30% of the total star formation in the galaxy when de- tected, consistent with another independent analysis from Rodríguez del Pino et al (2019).…”