Far-ultraviolet and X-ray observations of VV 114: feedback in a local analog to Lyman break galaxies.
GRIMES J.P., HECKMAN T., HOOPES C., STRICKLAND D., ALOISI A., MEURER G. and PTAK A.
Abstract (from CDS):
We have analyzed Far Ultraviolet Spectroscopic Explorer (FUSE), XMM-Newton, and Chandra observations of VV 114, a local galaxy merger with strong similarities to typical high-redshift Lyman break galaxies (LBGs). Diffuse thermal X-ray emission encompassing VV 114 has been observed by Chandra and XMM-Newton. This region of hot (kT∼0.59 keV) gas has an enhanced α/Fe element ratio relative to solar abundances and follows the same relations as typical starbursts between its properties (luminosity, size, and temperature) and those of the starburst galaxy (star formation rate, dust temperature, and galaxy mass). These results are consistent with the X-ray gas having been produced by shocks driven by a galactic superwind. The FUSE observations of VV 114 show strong, broad interstellar absorption lines with a pronounced blueshifted component (similar to what is seen in LBGs). This implies an outflow of material moving at ∼300-400 km/s relative to VV 114. The properties of the strong O VI absorption line are consistent with radiative cooling at the interface between the hot outrushing gas seen in X-rays and the cooler material seen in the other outflowing ions in the FUSE data. We show that the wind in VV 114 has not created a ``tunnel'' that enables more than a small fraction (<few percent) of the ionizing photons from VV 114 to escape into the intergalactic medium (IGM). Taken together, these data provide a more complete physical basis for understanding the outflows that seem to be generic in LBGs. This will lead to improved insight into the role that such outflows play in the evolution of galaxies and the IGM.