Feedback and feeding in the context of galaxy evolution with SPICA: direct characterization of molecular outflows and inflows

TL;DR

This paper discusses how the SPICA observatory's advanced infrared spectroscopy can detect and characterize molecular outflows and inflows in galaxies, shedding light on feedback processes influencing galaxy evolution over the last 10 billion years.

Contribution

It introduces a method to use SPICA's sensitivity to identify galaxy-scale gas flows and assesses their detectability across different galaxy types and redshifts.

Findings

Detectability of molecular outflows varies with galaxy type and redshift.

Infrared lines can reveal inflows and outflows in local and distant galaxies.

Synergies with other observatories enhance feedback studies.

Abstract

A far-infrared observatory such as the {\it SPace Infrared telescope for Cosmology and Astrophysics} ({\it SPICA}), with its unprecedented spectroscopic sensitivity, would unveil the role of feedback in galaxy evolution during the last $\sim10$ Gyr of the Universe ($z=1.5-2$), through the use of far- and mid-infrared molecular and ionic fine structure lines that trace outflowing and infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni line shapes and absorption blueshifted wings in molecular lines with high dipolar moments, and through emission line wings of fine-structure lines of ionized gas. We quantify the detectability of galaxy-scale massive molecular and ionized outflows as a function of redshift in AGN-dominated, starburst-dominated, and main-sequence galaxies, explore the detectability of metal-rich inflows in the local Universe, and describe the most significant synergies with other current and future observatories that will measure feedback in galaxies via complementary tracers at other wavelengths.