Determining the Hubble constant without the sound horizon scale: measurements from CMB lensing
| Autor: | Eric J. Baxter, Blake D. Sherwin |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
Cosmology and Nongalactic Astrophysics (astro-ph.CO) media_common.quotation_subject Horizon Cosmic microwave background Cosmic background radiation FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Universe Redshift symbols.namesake Space and Planetary Science symbols Planck Weak gravitational lensing Astrophysics - Cosmology and Nongalactic Astrophysics media_common Hubble's law |
| Zdroj: | Monthly Notices of the Royal Astronomical Society |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | Measurements of the Hubble constant, $H_0$, from the cosmic distance ladder are currently in tension with the value inferred from Planck observations of the CMB and other high redshift datasets if a flat $\Lambda$CDM cosmological model is assumed. One of the few promising theoretical resolutions of this tension is to invoke new physics that changes the sound horizon scale in the early universe; this can bring CMB and BAO constraints on $H_0$ into better agreement with local measurements. In this paper, we discuss how a measurement of the Hubble constant can be made from the CMB without using information from the sound horizon scale, $r_s$. In particular, we show how measurements of the CMB lensing power spectrum can be used to place interesting constraints on $H_0$ when combined with measurements of either supernovae or galaxy weak lensing, which constrain the matter density parameter. The constraints arise from the sensitivity of the CMB lensing power spectrum to the horizon scale at matter-radiation equality (in projection); this scale could have a different dependence on new physics than the sound horizon. From an analysis of current CMB lensing data from Planck and Pantheon supernovae with conservative external priors, we derive an $r_s$-independent constraint of $H_0 = 73.5\pm 5.3$ km/s/Mpc. Forecasts for future CMB surveys indicate that improving constraints beyond an error of $\sigma(H_0) = 3$ km/s/Mpc will be difficult with CMB lensing, although applying similar methods to the galaxy power spectrum may allow for further improvements. Comment: 14 pages, 6 figures; minor revision to match version accepted by MNRAS |
| Databáze: | OpenAIRE |
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