Probing the Evolution of the Galaxy Interaction/Merger Rate Using Collisional Ring Galaxies

Abstract

We present the results from our program to determine the evolution of the galaxy interaction/merger rate with redshift using the unique star-forming characteristics of collisional ring galaxies. We have identified 25 distant collisional ring galaxy candidates (CRGCs) in a total of 162 deep Hubble Space Telescope Wide Field/Planetary Camera-2 images obtained from the HST Archives. Based on measured and estimated redshifts, these 25 CRGCs all lie in the redshift interval of 0.1 ≤ z ≤ 1. Using the local collisional ring galaxy volume density and the new "standard" cosmology, we find that in order to account for the number of identified CRGCs in our surveyed fields, the galaxy interaction/merger rate, parameterized as (1 + z) m , must increase steeply with redshift. We determine a minimum value of m = 5.2 ± 0.7, though m could be as high as 7 or 8. We can rule out a non-evolving (m = 0) and weakly evolving (m = 1-2) galaxy interaction/merger rate at greater than the 4 sigma level of confidence.

On the nature of the apparent ring galaxy SDSS J075234.33+292049.8

“…The object discussed here represents a first attempt to bridge between the reasonably well‐studied but low‐redshift PRC sample and those derived from HST observations by Reshetnikov (1997), Lavery et al (2004) and Reshetnikov & Dettmar (2007). Since the most distant ring galaxies are few and not well‐studied, except by Lavery et al (1996, 2004), it may be useful to study objects more distant than those in the PRG but closer than those found on HST images that may bridge the distance gap to z ≃ 0.35. Such objects can serve also as templates to understand the high‐ z PRGs, once a larger sample will become available.…”

“…A comprehensive survey by Lavery et al (2004), from a visual inspection of 162 deep Hubble Space Telescope ( HST ) archival images, yielded 25 objects with redshifts from 0.35 ≤ z ≤ 1.0 that could possibly be ring galaxies. Note that these redshifts are, in most cases, estimates based on the assumption of a standard‐candle magnitude of M V =−21.1 mag for these objects.…”

ENVIRONMENTAL EFFECTS IN THE INTERACTION AND MERGING OF GALAXIES IN zCOSMOS

“…Estimates of m for systems identified as ongoing mergers or as close galaxy pairs soon to merge vary in the literature between 0 < m < 6 (see e.g. Zepf & Koo 1989, Carlberg et al 1994, Yee & Ellingson 1995, Neuschaefer et al 1995, Carlberg et al 2000, Le Fèvre et al 2000, Patton et al 2002, Lin et al 2004, Conselice et al 2003, Lavery et al 2004, Kartaltepe et al 2006, Kampczyk et al 2007, Lin et al 2008, Lotz et al 2008, de Ravel et al 2009, López-Sanjuan et al 2009, Bridge et al 2010). This variation likely reflects a number of different effects, including the use of different methods, different luminosity ranges of surveys, different selection criteria, various observational biases and different ways of handling incompleteness in galaxy surveys.…”

Statistics of interacting galaxies at z ∼ 0.7

“…The paper by Lavery et al (2004) on collisional ring galaxies gives a very large value of m. However, the sample of galaxies they used is small. In addition, the type of interaction itself in which one of the galaxies passes through the center of the other at a high velocity is so rare that the local space density of such objects and, consequently, the value of m are known poorly.…”

“…The second (morphological) approach is based on the frequency statistics of signatures of recent interactions and mergers in galaxies: structure distortions (Conselice et al 2003 and references therein), the presence of tidal tails and bridges (Reshetnikov 2000a(Reshetnikov , 2000bBridge et al 2010), polar rings (Reshetnikov 1997;Reshetnikov and Dettmar 2007), collisional rings (Lavery et al 2004), etc. The main problem of this method is that the basic tracers of dynamical perturbations of galaxies, as a rule, have a low surface brightness and they are difficult to observe at high z.…”