A VLT/FORS2 Narrowband Imaging Search for MgII Emission Around z ~ 0.7 Galaxies

Abstract

We perform a Very Large Telescope FOcal Reducer and low dispersion Spectrograph 2 (VLT/FORS2) narrowband imaging search around 5 star-forming galaxies at redshift z=0.67-0.69 in the Great Observatories Origins Deep Survey South (GOODS-S) field to constrain the radial extent of large-scale outflows traced by resonantly scattered MgII emission. The sample galaxies span star formation rates in the range 4 $M_{\odot }/yr$ < SFR < $40M_{\odot }/yr$ and have stellar masses $9.9\lesssim \log M_{\ast }/M_{\odot }\lesssim 11.0$, and exhibit outflows traced by MgII absorption with velocities ~150-420 km s${}^{-1}$ . These observations are uniquely sensitive, reaching surface brightness limits of 5.81 $\times$ $10^{-19}$ ergs sec ${}^{-1}$ cm${}^{-2}$ arcsec${}^2$ per 1 arcsec${}^2$ aperture (at 5$\sigma$ significance). We do not detect any extended emission around any of the sample galaxies, thus placing 5$\sigma$ upper limits on the brightness of extended MgII emission of $<6.51\times 10^{-19}$ ergs sec ${}^{-1}$ cm${}^{-2}$ arcsec${}^2$ at projected distances $R_{\perp }>8-21$ kpc. The imaging also resolves the MgII absorption observed toward each galaxy spatially, revealing approximately constant absorption strengths across the galaxy disks. In concert with radiative transfer models predicting the surface brightness of MgII emission for a variety of simple wind morphologies, our detection limits suggest that either (1) the extent of the MgII-emitting material in the outflows from these galaxies is limited to $\lesssim 20$ kpc; or (2) the outflows are anisotropic and/or dusty.

20 pages, 12 figures, 4 tables, accepted for publication in ApJ

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• The cold circumgalactic medium in emission: MgII halos in TNG50
• A Comparison of Circumgalactic MgII Absorption between the TNG50 Simulation and the MEGAFLOW Survey
• Metal line emission from galaxy haloes at z~1
• The MUSE Extremely Deep Field: a first panoramic view of an Mg II emitting intragroup medium
• The Baltimore Oriole's Nest: Cool Winds from the Inner and Outer Parts of a Star-Forming Galaxy at z=1.3
• A galactic outflow traced by its extended Mg II emission out to a $\sim 30$ kpc radius in the Hubble Ultra Deep Field with MUSE