Physics

Dark matter

Cosmic microwave background

Consistency (knowledge bases)

Mathematics

Hubble's law

Particle physics

Algorithm

Planck

Artificial intelligence

Dark energy

Cosmology

Lambda

Computer science

Astrophysics

Quantum mechanics

Anisotropy

Physical review. D/Physical review. D.

New physics increasing the expansion rate just prior to recombination is among the least unlikely solutions to the Hubble tension and would be expected to leave an important signature in the early integrated Sachs-Wolfe (eISW) effect, a source of cosmic microwave background (CMB) anisotropies arising from the time variation of gravitational potentials when the Universe was not completely matter dominated. Why, then, is there no clear evidence for new physics from the CMB alone, and why does the $\mathrm{\ensuremath{\Lambda}}$ cold dark matter ($\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$) model fit CMB data so well? These questions and the vastness of the Hubble tension theory model space provide the motivation for general consistency tests of $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$. I perform an eISW-based consistency test of $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ introducing the parameter ${A}_{\mathrm{eISW}}$, which rescales the eISW contribution to the CMB power spectra. A fit to Planck CMB data yields ${A}_{\mathrm{eISW}}=0.988\ifmmode\pm\else\textpm\fi{}0.027$, in perfect agreement with the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ expectation ${A}_{\mathrm{eISW}}=1$ and posing an important challenge for early-time new physics, which I illustrate in a case study focused on early dark energy (EDE). I explicitly show that the increase in ${\ensuremath{\omega}}_{c}$ needed for EDE to preserve the fit to the CMB, which has been argued to worsen the fit to weak lensing and galaxy clustering measurements, is specifically required to lower the amplitude of the eISW effect, which would otherwise exceed $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$'s prediction by $\ensuremath{\approx}20%$: this is a generic problem beyond EDE that likely applies to most models enhancing the expansion rate around recombination. Early-time new physics models invoked to address the Hubble tension are therefore faced with the significant challenge of making a similar prediction to $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ for the eISW effect while not degrading the fit to other measurements in doing so.

Consistency tests of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>CDM</mml:mi></mml:math> from the early integrated Sachs-Wolfe effect: Implications for early-time new physics and the Hubble tension

Consistency tests of ΛCDM from the early integrated Sachs-Wolfe effect: Implications for early-time new physics and the Hubble tension