Mapping Galactic Winds and Small-scale Structure in the Circumgalactic Medium with Habitable Worlds Observatory

TL;DR

This paper proposes using the Habitable Worlds Observatory to map the circumgalactic medium in ultraviolet emission lines, aiming to better understand galaxy evolution through detailed spatial and spectral observations.

Contribution

It introduces a novel observational strategy combining multi-object and integral field spectroscopy with HWO to study CGM structures and processes at multiple scales.

Findings

Proposes a new method for mapping CGM in emission.

Highlights the potential to resolve small-scale processes in the CGM.

Suggests improved understanding of galaxy feedback and accretion mechanisms.

Abstract

We present a science case for the Habitable Worlds Observatory (HWO) to map the circumgalactic medium (CGM) in emission by targeting ultraviolet emission lines, which trace the 10^4 - 10^6 K gas engaged in the feedback and accretion mechanisms driving galaxy evolution. While the CGM-galaxy connection is clearly evident through absorption line experiments and limited work done in optical and radio emission from the ground, the nature of this connection is poorly understood with regard to how these cosmic ecosystems exchange matter and energy. We outline a two-pronged experiment with Habitable Worlds Observatory (HWO) utilizing both multi-object spectroscopy to map kpc-scale CGM structures such as galactic superwinds and integral field spectroscopy to unveil the sub-kpc-scale processes such as thermal instabilities, which are theorized to govern the cool gas reservoirs long detected in pencil-beam absorption surveys. This article is an adaptation of a science case document developed by HWO's CGM/IGM Working Group.