|Authors:||M. S. Oey 1, A. N. Sawant 1,2, A. Danehkar 3, and 10 co-authors|
|Affiliations:||(1) University of Michigan, Department of Astronomy, Ann Arbor, USA; (2) Institute of Mathematics, Lausanne, Switzerland; (3) Eureka Scientific, Oakland, USA|
|Accepted by:||Astrophysical Journal|
We use the Hubble Space Telescope ACS camera to obtain the first spatially resolved, nebular imaging in the light of C IV 1548,1551 by using the F150LP and F165LP filters. These observations of the local starburst Mrk 71 in NGC 2366 show emission apparently originating within the interior cavity around the dominant super star cluster (SSC), Knot A. Together with imaging in He II 4686 and supporting STIS FUV spectroscopy, the morphology and intensity of the C IV nebular surface brightness and the C IV / He II ratio map provide direct evidence that the mechanical feedback is likely dominated by catastrophic radiative cooling, which strongly disrupts adiabatic superbubble evolution. The implied extreme mass loading and low kinetic efficiency of the cluster wind are reasonably consistent with the wind energy budget, which is probably enhanced by radiation pressure. In contrast, the Knot B SSC lies within a well-defined superbubble with associated soft X-rays and He II 1640 emission, which are signatures of adiabatic, energy-driven feedback from a supernova-driven outflow. This system lacks clear evidence of C IV from the limb-brightened shell, as expected for this model, but the observations may not be deep enough to confirm its presence. We also detect a small C IV-emitting object that is likely an embedded compact H II region. Its C IV emission may indicate the presence of very massive stars (> 100 $M_\odot$) or strongly pressure-confined stellar feedback.