Volume 449, Number 1, April I 2006
|Page(s)||23 - 32|
|Section||Cosmology (including clusters of galaxies)|
|Published online||16 March 2006|
Galaxy pairs in cosmological simulations: effects of interactions on star formation
Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
2 Facultad de Ciencias Astronómicas y Geofísicas, La Plata, Argentina e-mail: firstname.lastname@example.org
3 Instituto de Astronomía y Física del Espacio, Argentina e-mail: email@example.com
4 Observatorio Astronómico de la Universidad Nacional de Córdoba, Argentina
Accepted: 9 November 2005
We carried out a statistical analysis of galaxy pairs in hydrodynamical ΛCDM simulations. We focus on the triggering of star formation by interactions and analysed the enhancement of star formation activity in terms of orbital parameters. By comparing the data to a suitable sample of simulated galaxies without a nearby companion, we find that close encounters ( kpc h-1) may effectively induce star formation. However, our results suggest that the stability properties of systems and the spatial proximity are both relevant factors in the process of triggering star formation by tidal interactions. In order to assess the effects of projection and spurious pairs in observational samples, we constructed and analysed samples of pairs of galaxies in the simulations obtained in projection. We found a good agreement with observational results with a threshold at kpc h-1 for interactions to statistically enhance star formation activity. For pairs within kpc h-1, we estimated a contamination by spurious pairs, reduced to for close systems. We also found that spurious pairs more strongly affect high density regions, with of spurious pairs detected for low density regions compared to found in high density ones. We analysed the dependence of star formation on environment by defining the usual projected density parameter for both pairs and isolated galaxies in the simulations. We find the expected star formation-local density relation for both galaxies in pairs and without a close companion, with a stronger density dependence for close pairs which suggests a relevant role for interactions in driving this relation.
Key words: methods: numerical / cosmology: theory / Galaxy: formation / galaxies: interactions
© ESO, 2006
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