Spectroscopic Galaxy Cluster Measurements for the Dark Energy Survey
Physical and Biological Sciences
Thesis req. for BS in Physics (Astrophysics), some guidance in PHYS 182 course
Two galaxy clusters were observed using the DEIMOS instrument on the Keck II telescope over a total of 2.5 nights in the fourth quarter of 2014. These clusters were selected specifically so that the high precision spectroscopic measurements obtained through DEIMOS could be compared to the existing photometric measurements collected by the Dark Energy Survey (DES), ultimately allowing DES to constrain and calibrate their photometric redshifts. The DEIMOS observations were completed using a total of five slitmasks to allow the light from specific member galaxies in the clusters to be dispersed by the spectrograph and recorded by a CCD. After collecting the data, the two-dimensional spectra from several of the slitmasks were reduced using the Spec2d Data Reduction Pipeline. Next, one-dimensional object spectra were extracted for each galaxy and then used to determine the redshift of that galaxy, ultimately leading to a catalog of redshifts. Along with its utility in calculating the redshift, velocity dispersion, and mass of each cluster, the catalog of redshifts will complement the work of other DES groups who have observed lower redshift clusters. Ultimately, the combined catalog of redshifts will aid DES in constraining and calibrating their results.
