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Head-tail Galaxies: beacons of high-density regions in clusters

journal contribution
posted on 2023-05-17, 00:32 authored by Mao, MY, Johnston-Hollitt, M, Stevens, JB, Wotherspoon, SJ
Using radio data at 1.4 GHz from the Australia Telescope Compact Array (ATCA), we identify five head–tail (HT) galaxies in the central region of the Horologium–Reticulum Supercluster (HRS). Physical parameters of the HT galaxies were determined along with substructure in the HRS to probe the relationship between environment and radio properties. Using a density enhancement technique applied to 582 spectroscopic measurements in the 2°× 2° region about A3125/A3128, we find all five HT galaxies reside in regions of extremely high density (>100 galaxies Mpc−3). In fact, the environments surrounding HT galaxies are statistically denser than those environments surrounding non-HT galaxies and among the densest environments in a cluster. Additionally, the HT galaxies are found in regions of enhanced X-ray emission and we show that the enhanced density continues out to substructure groups of 10 members. We propose that it is the high densities that allow ram pressure to bend the HT galaxies as opposed to previously proposed mechanisms relying on exceptionally high peculiar velocities.

History

Publication title

Royal Astronomical Society. Monthly Notices

Volume

392

Pagination

1070-1079

ISSN

0035-8711

Department/School

School of Natural Sciences

Publisher

Wiley-Blackwell Publishing, Inc

Place of publication

Commerce Place, 350 Main Street, Malden, USA, MA

Rights statement

The definitive published version is available online at: http://interscience.wiley.com

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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