Feedback in the Local Lyman‐break Galaxy Analog Haro 11 as Probed by Far‐Ultraviolet and X‐Ray Observations

Abstract

We have reanalyzed FUSE data and obtained new Chandra observations of Haro 11, a local (DL = 88 Mpc) UV luminous galaxy. Haro 11 has a far-UV luminosity (1010.3 L☉), UV surface brightness (109.4 L☉ kpc-2), star formation rate (SFR), and metallicity similar to those observed in Lyman-break galaxies (LBGs). We show that Haro 11 has extended soft thermal (kT ~ 0.68 keV) X-ray emission of a luminosity and size which scales with the physical properties (e.g., SFR, stellar mass) of the host galaxy. An enhanced α/Fe ratio of ~4 relative to solar abundance suggests significant supernova enrichment. These results are consistent with the X-ray emission being produced in a shock between a supernova-driven outflow and the ambient material. The far-ultraviolet (FUV) spectra show strong absorption lines similar to those observed in LBG spectra. A blueshifted absorption component is identified as a wind outflowing at ~200-280 km s-1. O VI λλ1032,1038 emission, the dominant cooling mechanism for coronal gas at T ~ 105.5 K, is also observed. If associated with the outflow, the luminosity of the O VI emission suggests that 20% of the total mechanical energy from the supernovae and solar winds is being radiated away. This implies that radiative cooling through O VI is not significantly inhibiting the growth of the outflowing gas. In contradiction to the findings of Bergvall and coworkers, we find no convincing evidence of Lyman continuum leakage in Haro 11. We conclude that the wind has not created a tunnel allowing the escape of a significant fraction of Lyman continuum photons, and place a limit on the escape fraction of fesc 2%. Overall, both Haro 11 and a previously observed LBG analog, VV 114, provide invaluable insight into the X-ray and FUV properties of high-redshift LBGs.