Galaxies with conspicuous optical warps

Abstract

In this paper, we present results of a photometric and kinematic study for a sample of 13 edge-on spiral galaxies with pronounced integral shape warps of their stellar discs. The global structure of the galaxies is analysed on the basis of the Sloan Digital Sky Survey imaging, in the g, r and i passbands. Spectroscopic observations are obtained with the 6-m Special Astrophysical Observatory telescope. In general, galaxies of the sample are typical bright spiral galaxies satisfying the Tully-Fisher relation. Most of the galaxies reside in dense spatial environments and, therefore, tidal encounters are the most probable mechanism for generating their stellar warps. We carried out a detailed analysis of the galaxies and their warps and obtained the following main results: (i) maximum angles of stellar warps in our sample are about 20° (ii) warps start, on average, between 2 and 3 exponential scalelengths of a disc (iii) stronger warps start closer to the centre, weak warps start farther; (iv) warps are asymmetric, with the typical degree of asymmetry of about several degrees (warp angle); (v) massive dark halo is likely to preclude the formation of strong and asymmetric warps.