A surviving disk from a galaxy collision at z = 0.4Y. Yang1, F. Hammer1, H. Flores1, M. Puech2, 1, and M. Rodrigues1
1 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 5 Place Jules Janssen, Meudon, France
2 ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
Received 10 July 2008 / Accepted 1 April 2009
Context. Spiral galaxies dominate the local galaxy population. Disks are known to be fragile to collisions. Thus it is worthwhile to probe under what conditions a disk can possibly survive such interactions.
Aims. We present a detailed morpho-kinematic study of a massive galaxy with two nuclei, J033210.76–274234.6 , at z = 0.4.
Methods. The morphological analysis reveals that the object consists of two bulges and a massive disk, as well as a faint blue ring. Combining the kinematics with morphology we propose a near-center collision model for the object.
Results. We find that the massive disk is likely to have survived the collision of galaxies with an initial mass ratio of ~4:1. The N-body/Smoothed Particle Hydrodynamics (SPH) simulations show that the collision possibly is a polar collision with a very small pericentric distance of ~1 kpc, and that the remnant of the main galaxy will be dominated by a disk. The results support the disk survival hypothesis.
Conclusions. The survival of the disk is related to the polar collision with an extremely small pericentric distance. With the help of N-body/SPH simulations we find that the probability of disk survival is quite large regardless of whether the two galaxies merge or not.
Key words: galaxies: formation -- galaxies: evolution -- galaxies: kinematics and dynamics -- galaxies: interactions
© ESO 2009