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 propose an effective model to describe the backreaction on cosmologicalobservables induced by Laniakea, the gravitational supercluster hosting theMilky Way, which was defined using peculiar velocity data from Cosmicflows-4(CF4). The structure is well described by an ellipsoidal shape exhibitingtriaxial expansion, reasonably approximated by a constant expansion rate alongthe principal axes. Our best fits suggest that the ellipsoid, after subtractingthe background expansion, contracts along the two smaller axes and expandsalong the longest one, predicting an average expansion of $\sim -1.1~\rm{km}/\rm{s}/\rm{Mpc}$. The different expansion rates within the region,relative to the mean cosmological expansion, induce line-of-sight-dependentcorrections in the computation of luminosity distances. We apply thesecorrections to two low-redshift datasets: the Pantheon+ catalog of type IaSupernovae (SN~Ia), and 63 measurements of Surface Brightness Fluctuations(SBF) of early-type massive galaxies from the MASSIVE survey. We findcorrections on the distances of order $\sim 2-3\%$, resulting in a shift in theinferred best-fit values of the Hubble constant $H_0$ of order $\DeltaH_0^{\rm{SN~Ia}}\approx 0.5 ~\rm{km}/\rm{s}/\rm{Mpc}$ and $\DeltaH_0^{\rm{SBF}}\approx 1.1 ~\rm{km}/\rm{s}/\rm{Mpc}$, seemingly worsening theHubble tension.

An effective description of Laniakea and its backreaction: Impact on Cosmology and the local determination of the Hubble constant