The HIX galaxy survey II: HI kinematics of HI eXtreme galaxies

K. A. Lutz (1; 2); V. A. Kilborn (1); B. S. Koribalski (2); B.; Catinella (3); G. I. G. J\'ozsa (4; 5; 6); O. I. Wong (3); A. R. H.; Stevens (1; 3); D. Obreschkow (3); H. D\'enes (2; 7) ((1) Centre for; Astrophysics; Supercomputing; Swinburne University of Technology; (2); Australia Telescope National Facility; CSIRO Astronomy; Space Science; (3); International Centre for Radio Astronomy Research (ICRAR); The University of; Western Australia; (4) SKA South Africa Radio Astronomy Research Group; (5); Rhodes Centre for Radio Astronomy Techniques & Technologies; Department of; Physics; Electronics; (6) Argelander-Institut f\"ur Astronomie; (7); Research School of Astronomy; Astrophysics; The Australian National; University)

arXiv:1802.04043·astro-ph.GA·December 18, 2018

The HIX galaxy survey II: HI kinematics of HI eXtreme galaxies

K. A. Lutz (1, 2), V. A. Kilborn (1), B. S. Koribalski (2), B., Catinella (3), G. I. G. J\'ozsa (4, 5, 6), O. I. Wong (3), A. R. H., Stevens (1, 3), D. Obreschkow (3), H. D\'enes (2, 7) ((1) Centre for, Astrophysics, Supercomputing, Swinburne University of Technology, (2)

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TL;DR

This study investigates the properties of HI eXtreme galaxies, revealing that their high HI content is linked to higher angular momentum and warped disks, often inherited from their halos, and possibly enhanced by minor mergers.

Contribution

It provides a detailed analysis of HI kinematics in HIX galaxies, highlighting the role of angular momentum and halo properties in their extreme HI richness, using new observational and simulation data.

Findings

01

HIX galaxies have more warped HI disks and HI arms/tails.

02

They possess higher HI and baryonic specific angular momentum.

03

Most HIX galaxies reside in higher-spin halos.

Abstract

By analysing a sample of galaxies selected from the HI Parkes All Sky Survey (HIPASS) to contain more than 2.5 times their expected HI content based on their optical properties, we investigate what drives these HI eXtreme (HIX) galaxies to be so HI-rich. We model the HI kinematics with the Tilted Ring Fitting Code TiRiFiC and compare the observed HIX galaxies to a control sample of galaxies from HIPASS as well as simulated galaxies built with the semi-analytic model Dark Sage. We find that (1) HI discs in HIX galaxies are more likely to be warped and more likely to host HI arms and tails than in the control galaxies, (2) the average HI and average stellar column density of HIX galaxies is comparable to the control sample, (3) HIX galaxies have higher HI and baryonic specific angular momenta than control galaxies, (4) most HIX galaxies live in higher-spin haloes than most control…

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