Tully-Fisher analysis of the multiple cluster system Abell 901/902^⋆

¹ Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria
e-mail: benjamin.boesch@uibk.ac.at
² Department of Physics, Denys Wilkinson Building, University of Oxford, Keble Road, Oxford OX1 3RH, UK
³ Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia
⁴ School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
⁵ Department of Astronomy, University of Vienna, Türkenschanzstr. 17, 1180 Wien, Austria
⁶ Department of Physics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
⁷ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany

Received: 22 March 2013
Accepted: 19 April 2013

Abstract

Context.

Aims. We derive rotation curves from optical emission lines of 182 disc galaxies (96 in the cluster and 86 in the field) in the region of Abell 901/902 located at z ~ 0.165. We continue the kinematic analysis presented in a previous paper. Here, we focus on the analysis of B-band and stellar-mass Tully-Fisher relations. We examine possible environmental dependencies and differences between normal spirals and dusty red galaxies, i.e. disc galaxies that have red colours because of relatively low star formation rates.

Methods. Assuming a tilted ring model we simulate the spectroscopy of a given galaxy and reconstruct the maximum rotation velocity from the best-fitting simulated rotation curve. We fit regression lines adopting a maximum-likelihood method based on Bayes’ theorem to build B-band and stellar-mass Tully-Fisher relations.

Results. We find no significant differences between the best-fit Tully-Fisher slope of cluster and field galaxies. At fixed slope, the field population with high-quality rotation curves (57 objects) is brighter by ΔM_B = −0.^m42 ± 0.^m15 than the cluster population (55 objects). We show that this slight difference is at least in part an environmental effect. The scatter of the cluster Tully-Fisher relation increases for galaxies closer to the core region, also indicating an environmental effect. Interestingly, dusty red galaxies become fainter towards the core at a given rotation velocity (i.e. total mass). This indicates that the star formation in these galaxies is in the process of being quenched. The luminosities of normal spiral galaxies are slightly higher at fixed rotation velocity for smaller cluster-centric radii. These galaxies are probably gas-rich (compared to the dusty red population) and the onset of ram-pressure stripping increases their star-formation rates. Galaxies with smooth morphology show higher root mean square values in the fitting of their rotation curves. This is particularly the case for dusty red galaxies. A cluster-specific interaction process like ram-pressure stripping is the best explanation, since it only affects the gaseous disc but not the stellar morphology.

Conclusions. The results from the Tully-Fisher analysis are consistent with and complement our previous findings. Dusty red galaxies might be an intermediate stage in the transformation of infalling field spiral galaxies into cluster lenticulars (also known as S0s), and this might explain the well-known increase of the S0 fraction in galaxy clusters with cosmic time.