Characterizing gas flows through observations of the disk-CGM interface with the HWO

TL;DR

This paper emphasizes the importance of high-resolution ultraviolet spectroscopy with the Habitable Worlds Observatory to study gas flows at the disk-CGM interface, aiming to uncover pathways of matter exchange in galaxies.

Contribution

It proposes specific telescope parameters and observational strategies for future UV spectroscopic studies of the galaxy disk-CGM interface.

Findings

Advocates for high spectral resolution UV spectroscopy on HWO.

Recommends a multi-object spectrograph with thousands of slitlets.

Suggests capabilities to detect gas flows and characterize the disk-halo interface.

Abstract

How gas gets into, through, and out of galaxies is critical to understanding galactic ecosystems. The disk-CGM interface region is uniquely suited for studying processes that drive gas flows. Matter and energy that enter and leave a galaxy pass through this region; however, the precise pathways are yet to be explored. In this paper, we discuss future observations that will facilitate the discovery of the gas flow pathways in galaxies and the telescope parameters necessary for making those observations. We advocate for high spectral resolution ultraviolet spectroscopic capabilities on the Habitable Worlds Observatory (HWO) that will enable observations in a wavelength range of 940 - 3500 A (minimum range: 970 - 3000 A) and at a resolution of 100,000 (minimum of 50,000). We advocate 19 for a multi-object spectrograph with thousands of sub-arcsec slitlets and a field of view 6' x 6'. We also recommend that the spectrograph be sensitive enough to achieve a signal-to-noise ratio of 10 or higher within a few hours for a continuum source of 21 AB magnitude and estimate an optimal aperture size of 8 meters. These capabilities would enable the characterization of gas in the disk-halo interface, leading to breakthroughs in our understanding of the gas flows and galactic ecosystems.