Ultra-Luminous X-ray Sources in Haro 11 and the Role of X-ray Binaries in Feedback in Lyman-alpha Emitting Galaxies

TL;DR

This paper investigates the role of X-ray binaries in feedback mechanisms that facilitate Lyman-alpha emission escape in starburst galaxies, highlighting the potential influence of ultra-luminous X-ray sources on galaxy evolution.

Contribution

It identifies and characterizes two X-ray sources in Haro 11, proposing that X-ray binary feedback significantly impacts Lyman-alpha photon escape in early universe galaxies.

Findings

Haro 11 X-1 may be an intermediate mass black hole seed.

Haro 11 X-2 is likely an ultra-luminous X-ray binary.

X-ray binary winds could aid Lyman-alpha escape.

Abstract

Lyman Break Analogs (LBA) are local proxies of high-redshift Lyman Break Galaxies (LBG). Studies of nearby starbursts have shown that Lyman continuum and line emission are absorbed by dust and that the Lyman-alpha is resonantly scattered by neutral hydrogen. A source of feedback is required to prevent scattering and allow the Lyman-alpha emission to escape. There are two X-ray point sources embedded in the Lyman Break Analog (LBA) galaxy Haro 11. Haro 11 X-1 is an extremely luminous (L$_{X} \sim 10^{41}$ ergs s$^{-1}$), spatially compact source with a hard X-ray spectrum. Haro 11 X-1 is similar to the extreme Black Hole Binary (BHB) M82 X-1. The hard X-ray spectrum indicates Haro 11 X-1 may be a Black Hole Binary (BHB) in a low accretion state. The very high X-ray luminosity suggests an intermediate mass black hole that could be the seed for formation of a supermassive black hole. Source Haro 11 X-2 has an X-ray luminosity L$_{X} \sim 5\times10^{40}$ ergs s$^{-1}$ and a soft X-ray spectrum. This strongly suggests that Haro 11 X-2 is an X-ray binary in the ultra luminous state. Haro 11 X-2 is coincident with the star forming knot that is the source of the Lyman-alpha emission, raising the possibility that strong winds from X-ray binaries play an important part in injecting mechanical power into the Interstellar Medium (ISM), thus blowing away neutral material from the starburst region and allowing the Lyman-alpha to escape. We suggest that feedback from X-ray binaries may play a significant role in allowing Lyman-alpha emission to escape from galaxies in the early universe.