Galaxy pairs in cosmological simulations: effects of interactions on star formation

Free access article

Issue		A&A Volume 449, Number 1, April I 2006


Page(s)		23 - 32
Section		Cosmology (including clusters of galaxies)
DOI		http://dx.doi.org/10.1051/0004-6361:20053507

A&A 449, 23-32 (2006)
DOI: 10.1051/0004-6361:20053507

Galaxy pairs in cosmological simulations: effects of interactions on star formation

M. J. Perez^{1, 2, 3}, P. B. Tissera^{1, 3}, D. G. Lambas^{1, 4} and C. Scannapieco^{1, 3}

¹ Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
² Facultad de Ciencias Astronómicas y Geofísicas, La Plata, Argentina
e-mail: jperez@fcaglp.unlp.edu.ar
³ Instituto de Astronomía y Física del Espacio, Argentina
e-mail: patricia@iafe.uba.ar
⁴ Observatorio Astronómico de la Universidad Nacional de Córdoba, Argentina

(Received 24 May 2005 / Accepted 9 November 2005)

Abstract
We carried out a statistical analysis of galaxy pairs in hydrodynamical $\Lambda$ CDM 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 (r<30 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 $r_{\rm p} \sim 25$ kpc h^-1 for interactions to statistically enhance star formation activity. For pairs within $r_{\rm p} < 100$ kpc h^-1, we estimated a ${\sim}27 \%$ contamination by spurious pairs, reduced to ${\sim}19 \%$ for close systems. We also found that spurious pairs more strongly affect high density regions, with $17\%$ of spurious pairs detected for low density regions compared to $33\%$ 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

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.