Leader: Gabriella Quattropani
Email: gabriella.quattropani@hdr.mq.edu.au
Collaborators: Matt Owers, Mina Pak, Oguzhan Cakir, and anyone who wants to join
Topic: The future fate of ram-pressure affected cluster galaxies
Status: under review by Science Committee
Abstract: Ram pressure stripping (RPS) is a hydrodynamical mechanism that can strip ISM material from galaxies as they move through the hot intracluster medium (ICM) permeating galaxy clusters. This is a key process in the quenching of star formation as star forming material is effectively removed from the galaxy. Signatures of RPS can be seen in ionised gas emission by studying the kinematics as well as emission line ratios. Galaxies affected by RPS usually have a truncated gas disk compared to the stellar disk as well as asymmetric gas distributions, often in the form of an ionised gas tail. These signatures can often be spatially coincident along the line of sight with other ionising sources so similar studies utilising 1-component Gaussian fits are only able to identify the dominant ionising mechanism. To enable the disentanglement of the multiple ionisation sources we implement a multi-component Gaussian fitting routine. This takes advantage of the different kinematic signatures (in terms of velocity and velocity dispersion) and emission line flux ratios associated with different ionising mechanisms. Previous multi-component studies of SAMI RPS galaxies (CATID: 9011900166 and 9011900084) with larger FOV KOALA data revealed shock regions at the interface of the ICM and ISM on the leading edge of galaxy as well as a lack of photoionisation in the ionised gas tails, disparate from so called ‘jellyfish’ galaxies that often have star forming knots in their tails. This highlights three main questions we aim to answer in this study: (1) do we see shock-like structures in all RP affected galaxies at the ICM-ISM interface? (2) If not photoionisation, what excitation mechanism is ionising the tails? (3) What causes the different manifestations of tails in RP affected galaxies? HECTOR will provide a large sample of galaxies in clusters which will allow for a statistical analysis of the incidence of these shock-like regions in RP affected galaxies. In addition, the varying dynamical states of the clusters in the HECTOR survey may give insight into the environmental influences which affect the occurrence of photoionisation in tails.
Note: This may be multiple papers depending on the outcomes of the first data release.
Needed data products: flux calibrated spectra at each spaxel, stellar continuum fits and stellar kinematics, redshift, cluster membership information.
Publication Date: 01/12/2025