arXiv subjects

Caitlin Adams

Publications and source records attributed to Caitlin Adams.

3 recordsLinked to original sources

arXiv2020

Joint growth rate measurements from redshift-space distortions and peculiar velocities in the 6dF Galaxy Survey

We present a new model for the cross-covariance between galaxy redshift-space distortions and peculiar velocities. We combine this with the auto-covariance models of both probes in a fully self-consistent, maximum-likelihood method, allowing us to extract enhanced cosmological parameter constraints. When applying our method to the 6-degree Field Galaxy Survey (6dFGS), our constraint on the growth rate of structure is $fσ_8 = 0.384 \pm 0.052 \rm{(stat)} \pm 0.061 \rm{(sys)}$ and our constraint for the redshift-space distortion parameter is $β= 0.289^{+0.044}_{-0.043} \rm{(stat)} \pm 0.049 \rm{(sys)}$. We find that the statistical uncertainty for the growth rate of structure is reduced by 64% when using the complete covariance model compared to the redshift-space distortion auto-covariance model and 50% when compared to using the peculiar velocity auto-covariance model. Our constraints are consistent with those from the literature on combining multiple tracers of large-scale structure, as well as those from other 6dFGS analyses. Our measurement is also consistent with the standard cosmological model.

astro-ph.CO↗

arXiv2018

The SLUGGS Survey: A comparison of total-mass profiles of early-type galaxies from observations and cosmological simulations, to $\sim$4 effective radii

We apply the Jeans Anisotropic MGE (JAM) dynamical modelling method to SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey data of early-type galaxies in the stellar mass range $10^{10} 10^{10.7}{\rm M}_{\odot}$ in the Magneticum simulations, we identify a significant anticorrelation between total-mass density profile slopes and the fraction of stellar mass formed ex situ (i.e. accreted), whereas this anticorrelation is weaker for lower stellar masses, implying that the measured total mass density slopes for low-mass galaxies are less likely to be determined by merger activity.

astro-ph.GA↗

arXiv2017

Improving constraints on the growth rate of structure by modelling the density-velocity cross-correlation in the 6dF Galaxy Survey

We present the first simultaneous analysis of the galaxy overdensity and peculiar velocity fields by modelling their cross-covariance. We apply our new maximum-likelihood approach to data from the 6-degree Field Galaxy Survey (6dFGS), which has the largest single collection of peculiar velocities to date. We present a full derivation of the analytic expression for the cross-covariance between the galaxy overdensity and peculiar velocity fields and find direct evidence for a non-zero correlation between the fields on scales up to $\sim50 h^{-1}$ Mpc. When utilising the cross-covariance, our measurement of the normalised growth rate of structure is $fσ_8(z=0) = 0.424^{+0.067}_{-0.064}$ (15% precision), and our measurement of the redshift-space distortion parameter is $β=0.341^{+0.062}_{-0.058}$ (18% precision). Both measurements improve by $\sim$20% compared to only using the auto-covariance information. This is consistent with the literature on multiple-tracer approaches, as well as Fisher matrix forecasts and previous analyses of 6dFGS. Our measurement of $fσ_8$ is consistent with the standard cosmological model, and we discuss how our approach can be extended to test alternative models of gravity.

astro-ph.CO↗