Аннотация
Mapping Mg II resonance emission scattered by galactic winds offers a means
to determine the spatial extent and density of the warm outflow. Using
Keck/LRIS spectroscopy, we have resolved scattered Mg II emission to the east
of 32016857, a star-forming galaxy at z =0.9392 with an outflow. The Mg II
emission from this galaxy exhibits a P-Cygni profile, extends further than both
the continuum and O II emission along the eastern side of the slit, and has a
constant Doppler shift along the slit which does not follow the velocity
gradient of the nebular O II emission. Using the Sobolev approximation, we
derive the density of Mg+ ions at a radius of 12 to 18 kpc in the outflow. We
model the ionization correction and find that much of the outflowing Mg is in
Mg++. We estimate that the total mass flux could be as large as 330 - 500 solar
masses per year, with the largest uncertainties coming from the depletion of Mg
onto grains and the clumpiness of the warm outflow. We show that confining the
warm clouds with a hot wind reduces the estimated mass flux of the warm outflow
and indicates amass-loading factor near unity in the warm phase alone. Based on
the high blue luminosities that distinguish 32016857 and TKRS 4389, described
by Rubin et al. 2011, from other galaxies with P-Cygni emission, we suggest
that, as sensitivity to diffuse emission improves, scattering halos may prove
to be a generic property of star-forming galaxies at intermediate redshifts.
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