An HI view of the on-going assembly of early-type galaxies: present and future observations

TL;DR

This study analyzes the neutral hydrogen (HI) properties of early-type galaxies in the ATLAS3D sample, revealing environmental effects on HI morphology and kinematics, and discusses future observations with next-generation radio instruments.

Contribution

It provides the first comprehensive analysis of HI in early-type galaxies across different environments using WSRT and Alfalfa data, and demonstrates future observational prospects with simulated Apertif data.

Findings

HI detected in about half of the galaxies outside Virgo

HI morphology varies with environment, from regular to disturbed

Galaxies in Virgo nearly lack HI

Abstract

We present a preliminary analysis of the HI properties of early-type galaxies in the ATLAS3D sample. Using WSRT data for ~100 galaxies outside the Virgo cluster and data from the Alfalfa project for galaxies inside Virgo, we discuss the dependence of HI properties on environment. We detect HI in about half of the galaxies outside Virgo. For these systems, the HI morphology and kinematics change as a function of environment, going from regular, rotating systems around isolated galaxies to progressively more disturbed structures for galaxies with neighbours or in groups. In denser environment, inside Virgo, nearly none of the galaxies contains HI. We discuss future work in this field which will be enabled by next-generation, pre-SKA radio instruments. We present a simulated Apertif HI observation of an ATLAS3D early-type galaxy, showing how its appearance and detection level vary as a function of redshift.