Resolving the ultraluminous X-ray sources in the Ly α emitting galaxy Haro 11

Abstract

ABSTRACT Lyman continuum and line emission are thought to be important agents in the reionization of the early Universe. Haro 11 is a rare example of a local galaxy in which Ly α and continuum emission have escaped without being absorbed or scattered by ambient gas and dust, potentially as a consequence of feedback from its X-ray sources. We build on our previous Chandra analysis of Haro 11 by analysing three new observations. Our subpixel spatial analysis reveals that the two previously known X-ray sources are each better modelled as ensembles of at least two unresolved point sources. The spatial variability of these components reveals X1 as a dynamical system where one luminous X-ray source (LX ∼ 1041 erg s−1) fades as a secondary source begins to flare. These might be intermediate-mass black holes or low-luminosity active galactic nuclei (AGNs) near the centre of the galaxy in the process of merging. Optical emission line diagnostics drawn from the literature suggest that while the galaxy as a whole is consistent with starburst signatures of ionization, the individual regions wherein the X-ray sources reside are more consistent with AGN/composite classification. The sources in X2 exhibit some degree of flux variability. X2a dominates the flux of this region during most observations (LX ∼ 6 × 1040 erg s−1), and gives the only evidence in the galaxy of a soft ultraluminous X-ray source capable of high-energy winds, which we suggest are responsible for allowing the coincident Ly α emission to escape.