The Distance and Peculiar Velocity of the Norma cluster (ACO 3627) using the Near-Infrared $J$ and $K_s$-band Fundamental Plane Relations

TL;DR

This study measures the distance and peculiar velocity of the Norma cluster using near-infrared Fundamental Plane relations, providing insights into its motion and supporting its small peculiar velocity.

Contribution

It presents the largest near-infrared Fundamental Plane sample for the Norma cluster, improving distance and velocity estimates in the Great Attractor region.

Findings

Distance to Norma cluster: 4915 ± 121 km/s

Peculiar velocity of Norma: 44 ± 151 km/s

Supports small peculiar velocity for Norma

Abstract

We report distance measurements for the Norma cluster based on the near-infrared $J$- and $K_s$-band Fundamental Plane (FP) relations. Our simultaneous $J$ and $K_s$-band photometry analyses were performed using 31 early-type galaxies in the nearby Norma cluster obtained using the 1.4 m InfraRed Survey Facility (IRSF) at the South African Astronomical Observatory. Our final $K_s$-band FP sample consists of 41 early-type galaxies from the Norma cluster observed using the IRSF and the New Technology Telescope (NTT) at the European Southern Observatory. This is the largest cluster sample used for peculiar velocity studies in the Great Attractor region to date. From the $K_s$-band FP, we find a distance to the Norma cluster of $4915 \pm 121$ km s$^{-1}$. The implied peculiar velocity for Norma is $44 \pm 151$ km s$^{-1}$ which further supports a small peculiar velocity for the Norma cluster.