Interacting galaxies: co-rotating and counter-rotating systems with tidal tails

Valeria Mesa; Fernanda Duplancic; Sol Alonso; Georgina Coldwell; Diego G. Lambas

doi:10.1093/mnras/stt2317

paper

Interacting galaxies: co-rotating and counter-rotating systems with tidal tails

arXiv:1312.0560 · doi:10.1093/mnras/stt2317

Abstract

We analyse interacting galaxy pairs with evidence of tidal features in the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). The pairs were selected within $z < 0.1$ by requiring a projected separation $r_p < 50 \kpc$ and relative radial velocity $ΔV < 500 \kms$. We complete spectroscopic pairs using galaxies with photometric redshifts considering $ΔV_{phot} < 6800 \kms$, taking into account the mean photometric redshift uncertainty. We classify by visual inspection pairs of spirals into co-rotating and counter-rotating systems. For a subsample of non-AGN galaxies, counter-rotating pairs have larger star formation rates, and a higher fraction of young, star-forming galaxies. These effects are enhanced by restricting to $r_p < 12 \kpc$. The distributions of $C$ , $D_{n} (4000)$ and $(M_{u} - M_{r})$ for AGN galaxies show that counter-rotating hosts have bluer colours and younger stellar population than the co-rotating galaxies although the relative fractions of Seyfert, Liner, Composite and Ambiguous AGN are similar. Also, counter-rotating hosts have more powerful AGN as revealed by enhanced $Lu m [O I I I]$ values. The number of co-rotating systems is approximately twice the number of counter-rotating pairs which could be owed to a more rapid evolution of counter-rotating systems, besides possible different initial conditions of these interacting pairs.

11 pages, 8 figures accepted for publication in Monthly Notices of the Royal Astronomical Society

Interacting galaxies: co-rotating and counter-rotating systems with tidal tails

Abstract

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