Tidal Interactions and Mergers in Intermediate-redshift EDisCS Clusters

Sinan Deger, Gregory Rudnick, Kshitija Kelkar, Alfonso Aragón-Salamanca, Vandana Desai, Jennifer M. Lotz, Pascale Jablonka, John Moustakas, Dennis Zaritsky

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1 Scopus citations

Abstract

We study the fraction of tidal interactions and mergers (TIMs) with well-identified observability timescales (f TIM) in group, cluster, and accompanying field galaxies and its dependence on redshift (z), cluster velocity dispersion (σ), and environment analyzing Hubble Space Telescope/ACS images and catalogs from the ESO Distant Cluster Survey. Our sample consists of 11 clusters, seven groups, and accompanying field galaxies at 0.4 ≤ z ≤ 0.8. We derive f TIM using both a visual classification of galaxy morphologies and an automated method, the G - M 20 method. We calibrate this method using the visual classifications that were performed on a subset of our sample. We find marginal evidence for a trend between f TIM and z, in that higher z values correspond to higher f TIM. However, we also cannot rule out the null hypothesis of no correlation at higher than 68% confidence. No trend is present between f TIM and σ. We find that f TIM shows suggestive peaks in groups, and tentatively in clusters at R > 0.5 × R 200, implying that f TIM gets boosted in these intermediate-density environments. However, our analysis of the local densities of our cluster sample does not reveal a trend between f TIM and density, except for a potential enhancement at the very highest densities. We also perform an analysis of projected radius-velocity phase space for our cluster members. Our results reveal that TIM and undisturbed galaxies only have a 6% probability of having been drawn from the same parent population in their velocity distribution and 37% in radii, in agreement with the modest differences obtained in f TIM at the clusters.

Original languageEnglish (US)
Article number6
JournalAstrophysical Journal
Volume869
Issue number1
DOIs
StatePublished - Dec 10 2018

Keywords

  • galaxies: clusters: general
  • galaxies: evolution
  • galaxies: groups: general
  • galaxies: interactions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Deger, S., Rudnick, G., Kelkar, K., Aragón-Salamanca, A., Desai, V., Lotz, J. M., Jablonka, P., Moustakas, J., & Zaritsky, D. (2018). Tidal Interactions and Mergers in Intermediate-redshift EDisCS Clusters. Astrophysical Journal, 869(1), [6]. https://doi.org/10.3847/1538-4357/aaeb87