Kinematics, Structure, and Mass Outflow Rates of Extreme Starburst Galactic Outflows

Author(s)

Serena Perrotta, Alison L. Coil, David S. N. Rupke, Christy A. Tremonti, Julie D. Davis, Aleksandar M. Diamond-Stanic, J. E. Geach, Ryan C. Hickox, J. Moustakas, Gregory H. Rudnick, Paul H. Sell, Cameren Swiggum, Kelly E. Whalen

Abstract

We present results on the properties of extreme gas outflows in massive (M

_* ∼ 10

¹¹ M

_⊙), compact, starburst (star formation rate, SFR∼ 200 M

_⊙ yr

⁻¹) galaxies at z = 0.4-0.7 with very high star formation surface densities (Σ

_SFR ∼ 2000 M

_⊙ yr

⁻¹ kpc

⁻²). Using optical Keck/HIRES spectroscopy of 14 HizEA starburst galaxies, we identify outflows with maximum velocities of 820-2860 km s

⁻¹. High-resolution spectroscopy allows us to measure precise column densities and covering fractions as a function of outflow velocity and characterize the kinematics and structure of the cool gas outflow phase (T ∼ 10

⁴ K). We find substantial variation in the absorption profiles, which likely reflects the complex morphology of inhomogeneously distributed, clumpy gas and the intricacy of the turbulent mixing layers between the cold and hot outflow phases. There is not a straightforward correlation between the bursts in the galaxies’ star formation histories and their wind absorption line profiles, as might naively be expected for starburst-driven winds. The lack of strong Mg ii absorption at the systemic velocity is likely an orientation effect, where the observations are down the axis of a blowout. We infer high mass outflow rates of ∼50-2200 M

_⊙ yr

⁻¹, assuming a fiducial outflow size of 5 kpc, and mass loading factors of η ∼ 5 for most of the sample. While these values have high uncertainties, they suggest that starburst galaxies are capable of ejecting very large amounts of cool gas that will substantially impact their future evolution.

Organisation(s)

Department of Astrophysics

External organisation(s)

University of Kansas, University of California, San Diego, Rhodes College, University of Wisconsin, Madison, Bates College, University of Hertfordshire, Dartmouth College, Siena College, University of Florida, Gainesville

Journal

The Astrophysical Journal

Volume

949

No. of pages

35

ISSN

0004-637X

DOI

https://doi.org/10.3847/1538-4357/acc660

Publication date

05-2023

Peer reviewed

Yes

Austrian Fields of Science 2012

103003 Astronomy, 103004 Astrophysics

ASJC Scopus subject areas

Astronomy and Astrophysics, Space and Planetary Science

Portal url

https://ucrisportal.univie.ac.at/en/publications/87670432-a885-4181-ba44-6da9e9d0e4b8

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