The Coma Cluster (Abell 1656) is the nearest very large galaxy cluster to us. Look up the positions and redshifts of a s

[answerhappygod]

The Coma Cluster Abell 1656 Is The Nearest Very Large Galaxy Cluster To Us Look Up The Positions And Redshifts Of A S 1 (150.99 KiB) Viewed 68 times

The Coma Cluster (Abell 1656) is the nearest very large galaxy cluster to us. Look up the positions and redshifts of a sample of Coma member galaxies (the more the better!) a) Find the cluster centre (position and redshift) based on a simple mean. How far off are you from published values for the cluster centre? b) Plot a histogram of cluster member redshifts. Using the redshifts of the galaxies in your sample, what is the cluster velocity dispersion? Does this agree with published values? (note Coma is low redshift, so z~v/c) c) Plot a radial profile of the projected number density of galaxies in Coma (y axis is # of galaxies per area, x axis is radius in arcseconds). Note the radius is found by measuring the angle between the individual galaxy and the cluster center. Since angles on the sky are on the surface of a sphere the radius is not simply V(Ax)2 + (Ay)?), instead the angular radius can be calculated as (where gal = galaxy and cent = cluster centre): T=V 9 - (RAgal – RAcent) * cos(Deccent))2 + (Decgal – Deccent)2