English

Observational Constraints on the Multiphase Nature of Outflows Using Large Spectroscopic Surveys at $z\sim$0

Astrophysics of Galaxies 2020-04-22 v1

Abstract

Mass outflow rates and loading factors are typically used to infer the quenching potential of galactic-scale outflows. However, these generally rely on observations of a single gas phase which can severely underestimate the total ejected gas mass. To address this, we use observations of high mass (\geqslant1010^{10} M_{\odot}), normal star-forming galaxies at zz\sim0 from the MaNGA, xCOLD GASS, xGASS and ALFALFA surveys and a stacking of NaD, Hα\alpha, CO(1-0) and HI 21cm tracers with the aim of placing constraints on an average, total mass outflow rate and loading factor. We find detections of outflows in both neutral and ionised gas tracers, with no detections in stacks of molecular or atomic gas emission. Modelling of the outflow components reveals velocities of |vNaD_{\text{NaD}}|=131 km s1^{-1} and |vHα_{\text{H}\alpha}|=439 km s1^{-1} and outflow rates of M˙NaD\dot{M}_{\text{NaD}}=7.55 M_{\odot}yr1^{-1} and M˙Hα\dot{M}_{\text{H}\alpha}=0.10 M_{\odot}yr1^{-1} for neutral and ionised gas, respectively. Assuming a molecular/atomic outflow velocity of 200 km s1^{-1}, we derive upper limits of M˙CO<\dot{M}_{\text{CO}}<19.43 M_{\odot}yr1^{-1} and M˙HI<\dot{M}_{\text{HI}}<26.72 M_{\odot}yr1^{-1} for the molecular and atomic gas, respectively. Combining the detections and upper limits, we find average total outflow rates of M˙tot\dot{M}_{\text{tot}}\lesssim27 M_{\odot}yr1^{-1} and a loading factor of ηtot\eta_{\text{tot}}\lesssim6.39, with molecular gas likely contributing \lesssim72% of the total mass outflow rate, and neutral and ionised gas contributing \sim28% and <<1%, respectively. Our results suggest that, to first order, a degree of quenching via ejective feedback could occur in normal galaxies when considering all gas phases, even in the absence of an AGN.

Keywords

Cite

@article{arxiv.2004.06116,
  title  = {Observational Constraints on the Multiphase Nature of Outflows Using Large Spectroscopic Surveys at $z\sim$0},
  author = {Guido Roberts-Borsani},
  journal= {arXiv preprint arXiv:2004.06116},
  year   = {2020}
}

Comments

13 pages, 9 figures. Accepted for publication in MNRAS