Improving Hickson-like compact group finders in redshift surveys

EUGENIA DIAZ-GIMENEZ; ARIEL ZANDIVAREZ; ANTONELA TAVERNA

Córdoba, Argentina

Congreso; VIII FoF Meeting; 2018

IATE - Observatorio Astronómico de Córdoba

In this work, we present an algorithm to identify compact groups of galaxies that closely follows Hickson´s original aim and that improves its implementation on redshift surveys to obtain complete samples of compact groups. The methodology is tested on a mock lightcone of galaxies built from the outputs of a seminanalytic model of galaxy formation run on top of the Millennium Simulation I after scaling to represent the first-year Planck cosmology. The new algorithm is able to identify twice the number of CGs than previous versions of it, without changing the percentage of groups that are contaminated by interlopers. A brand new catalogue of compact groups from the Sloan Digital Sky Survey is the natural corollary of this study. The publicly available sample of 461 observational groups fulfil all the ideal compact group requirements: compactness, isolation and velocity concordance of all of their members.