RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 21 July 2016, 14:00-15:00; Duffield Lecture Theatre

Changbom Park

"Cosmological Constraints from the Redshift Dependence of Galaxy Clustering Anisotropy"

A new method for measuring the cosmological parameters governing the expansion history of the universe is introduced. The method uses the Alcock-Paczynski (AP) test applied to the shape of the galaxy two-point correlation function along and across the line-of-sight. The redshift-space distortion (RSD) effects have been the major obstacle for the AP test. We find that the RSD effects on the correlation function are large at a given redshift but do not vary much as redshift increases, and that the shape of the correlation function is nearly conserved. If a wrong cosmology is adopted, the conversion from the observed galaxy redshift to comoving distance results in distortion of the shape of the correlation function that varies systematically in redshift. We applied to this method to simulated data and also to the recent SDSS DR12 galaxy survey data to obtain an impressive constraint on the dark energy equation of state w and matter density parameter omega_m.