English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We revisit the degeneracy between the Hubble constant, $H_0$, and matterdensity, $\Omega_m$, for current cosmic microwave background (CMB) observationswithin the standard $\Lambda CDM$ model. We show that Planck, WilkinsonMicrowave Anisotropy Probe (WMAP), South Pole Telescope (SPT), and AtacamaCosmology Telescope Polarimeter (ACTPol) temperature power spectra producedifferent values of the exponent $x$ from minimizing the variance of theproduct $\Omega_mH_0^x$. The distribution of $x$ from the different data setsdoes not follow the Markov Chain Monte Carlo (MCMC) best-fit values for $H_0$or $\Omega_m$. Particularly striking is the difference between Planckmultipoles $\ell\leq800$ ($x=2.81$), and WMAP ($x = 2.94$), despite verysimilar best-fit cosmologies. We use a Fisher matrix analysis to show that, infact, this range in exponent values is exactly as expected in $\Lambda CDM$given the multipole coverage and power spectrum uncertainties for eachexperiment. We show that the difference in $x$ from the Planck $\ell \leq 800$and WMAP data is explained by a turning point in the relationship between $x$and the maximum effective multipole, at around $\ell=700$. The value of $x$ isdetermined by several physical effects, and we highlight the significant impactof gravitational lensing for the high-multipole measurements. Despite thespread of $H_0$ values from different CMB experiments, the experiments areconsistent with their sampling of the $\Omega_m-H_0$ degeneracy and do not showevidence for the need for new physics or for the presence of significantunderestimated systematics according to these tests. The Fisher calculationscan be used to predict the $\Omega_m-H_0$ degeneracy of future experiments.

Quantifying the CMB Degeneracy Between the Matter Density and Hubble Constant in Current Experiments