Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies

John Chisholm , Christy A. Tremonti , Claus Leitherer , Yanmei Chen , Aida Wofford (1) , Britt Lundgren

1 IAP - Institut d'Astrophysique de Paris

We report on a sample of 48 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We measure the kinematics of warm gas in galactic outflows using a combination of four Si ii absorption lines. We use multi-wavelength ancillary data to estimate stellar masses (M_*), star formation rates (SFR), circular velocities (v_circ), and morphologies. The galaxies cover four orders of magnitude in M_* and SFR, and sample a wide range of morphologies from starbursting mergers to normal star-forming galaxies. We derive 3.0-3.5σ relations between outflow velocity and SFR, M_*, and v_circ. The outflow velocities scale as SFR^0.08-0.22, {M}_*^0.12-0.20 and {v}_{circ}^0.44-0.87, with the range depending on whether we use a maximum or a central velocity to quantify the outflow velocity. After accounting for their increased SFR, mergers drive 32% faster outflows than non-merging galaxies, with all of the highest velocity outflows arising from mergers. Low-mass galaxies (log(M_*/ M_⊙) < 10.5) lose some low-ionization gas through galactic outflows, while more massive galaxies retain all of their low-ionization gas, unless they undergo a merger.

Keywords: galaxies: evolution; galaxies: formation; galaxies: starburst; Astrophysics - Astrophysics of Galaxies; Astrophysics - Cosmology and Nongalactic Astrophysics

Domains: Sciences of the Universe [physics]

John Chisholm, Christy A. Tremonti, Claus Leitherer, Yanmei Chen, Aida Wofford, et al.. Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies. The Astrophysical Journal, 2015, 811, ⟨10.1088/0004-637X/811/2/149⟩. ⟨insu-03644725⟩