Does the Great Attractor partake in large scale motions?

Abstract

The Norma cluster is a very rich, massive nearby galaxy cluster lying at or close to the ‘core’ of the Great Attractor (GA). A carefully determined redshift-independent distance and peculiar velocity of this cluster, therefore, helps us clarify if the GA partakes in large-scale motions. We have thus determined the distance and peculiar velocity of the Norma cluster using the Ks-band isophotal Tully-Fisher relation. Using near-infrared Ks-band isophotal magnitudes and Hi line widths for 12 late-type galaxies, six of which lie within the Norma cluster, the measured distance of the Norma cluster is 4893 ± 329 km s−1 (d = 69.4 ± 4.7 Mpc). The corresponding peculiar velocity is +61± 329 km s−1, which although with large uncertainty, is consistent with zero.