Distances from Stellar Kinematics for Peculiar Virgo Cluster Spiral Galaxies

TL;DR

This study estimates distances to peculiar Virgo cluster spiral galaxies using stellar kinematics, revealing discrepancies with HI-based distances likely caused by environmental effects such as gravitational interactions.

Contribution

It introduces a method combining stellar kinematics and synthetic rotation curves to improve distance estimates for disturbed cluster galaxies.

Findings

Most galaxies are within 4 Mpc of the cluster core.

Discrepancies between stellar and HI distances are linked to gas distribution and motions.

Environmental effects can bias gas-based distance measurements.

Abstract

We present distance estimates for eleven peculiar Virgo cluster spiral galaxies based on measurements of the stellar kinematics of their central 2 kpc. Stellar circular velocities were obtained using two-integral dynamical models. Distances were obtained by comparing, at each radius, the stellar circular velocities with synthetic H_alpha rotation curves derived from NIR Tully-Fisher relations.The results show that most of our galaxies are located within 4 Mpc of the core of the cluster. Three of these galaxies, previously classified as "low rotator galaxies" or with "Truncated/Compact" H_alpha radial distributions, have stellar kinematics-based distances that are discrepant with HI-based distances by at least 60%, and are likely to be located within the virial radius of the cluster. These discrepancies appear due to very truncated gas distributions plus non-circular gas motions or gas motions not in the plane of the stellar disk, perhaps as the result of gravitational interactions. Our results show that environmental effects can significantly reduce the measured HI linewidths for some disturbed cluster galaxies, thus affecting the accurate determination of distances based on gas kinematics methods.