Beyond H_0 and q_0: Cosmology is no longer just two numbers
Abstract
For decades, H_0 and q_0 were the quest of cosmology, as they promised to characterize our "world model" without reference to a specific cosmological framework. Using Monte Carlo simulations, we show that q_0 cannot be directly measured using distance indicators with both accuracy (without offset away from its true value) and precision (small error bar). While H_0 can be measured with accuracy and precision, to avoid a small bias in its direct measurement (of order 5%) we demonstrate that the pair H_0 and Omega_M (assuming flatness and w = -1) is a better choice of two parameters, even if our world model is not precisely LambdaCDM. We illustrate with analysis of the Constitution set of supernovae and indirectly infer q_0 = -0.57+/-0.04. Finally, we show that it may be possible to directly determine q_0 with both accuracy and precision using the time dependence of redshifts ("redshift drift").
Keywords
Cite
@article{arxiv.1209.0480,
title = {Beyond H_0 and q_0: Cosmology is no longer just two numbers},
author = {Abraham R. Neben and Michael S. Turner},
journal= {arXiv preprint arXiv:1209.0480},
year = {2015}
}
Comments
9 pages, 10 figures. Replaced with accepted version (includes 2 new figures showing more quantitative analysis/comparison of redshift drift surveys and distance indicator surveys, as well as some minor reorganization)