PHYSICAL PARAMETERS OF ABELL 2040 GALAXY CLUSTER AND GALAXY GROUPS AROUND IT

• Main Author: Arsyisyah Noor, Yulia
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/77101
• Institution: Institut Teknologi Bandung

A galaxy cluster is a structure consisting of hundreds to thousands of galaxies, hot x-ray-emitting gas, and dark matter that are bound together by gravity, being one of the largest structures in the universe. A swarm of galaxies can be categorized as a galaxy cluster if the swarm has a mass of at least M ? 3×1014M?, formed by 50 galaxies, and has a density high enough to keep the forming galaxies in a certain radius r from the navel. A galaxy cluster can be tested by existing theories to know its physical parameters. The galaxy cluster this thesis will examine is Abell 2040 galaxy cluster, which is registered in The Abell Catalogue (1958). While the data source is from Sloan Digital Sky Survey Data Release 18 (SDSS DR18). The purpose of this thesis is to know the physical parameters, which consist of its morphology, redshift, projection radius, membership, mass, and local group galaxies. There are several methods used in the data processing. To specify what Abell 2040 galaxy cluster is defined into, this thesis uses a statistical approach by (Bukhari dan Cram, 2003) and Cut and Enhance method (Goto et al., 2002). On the Bukhari method, clustering galaxies is based on its projection radius and radial velocity. Evaluating galaxies’ membership is done by enlarging Sr and Sv values multiplied by 10%, cluster that has S?r dan S?v value below Sr and Sv value is qualified for the galaxy cluster membership. While the Cut and Enhance method is determined by 2 stages, the first stage is color cut that uses color and magnitude correlation using a color cut of g – r, r – i, and i – z with bin used for each are 0,2; 0,1; and 0,1. The second stage is Enhance to evaluate the galaxy cluster membership by using the result from the Color Cut stage. Both methods are then compared to increase accuracy in determining the physical parameters of the Abell 2040 galaxy cluster. While Projected Mass Estimator method by Heisler in 1985, which was designed to avoid problems found in the virial theorem, is used to get the galaxy cluster mass value. The result after data processing is that Abell 2040 galaxy cluster has morphology of III ? E, 0.045055 redshift, 207.327 Mpc luminosity distance, projection radius 1.8 Mpc, and has 122 galaxy members with mass 1.58×1015M?.