Extremely excited about my latest work with Leo Giani, Cullan Howlett, Khaled Said, and Tam Davis (all four from the University of Queensland), where we study the impact of Laniakea, the supercluster hosting the Milky Way (also known as our home in the Cosmos) on local cosmological measurements and in particular measurements of the Hubble constant. Our initial hope was that taking into account the local inhomogeneities and anisotropies induced by Laniakea could help alleviate the Hubble tension - surprisingly, we found the opposite! The reason in short is that Laniakea is on average overdense compared to the cosmological background in which it resides, so its effect is the opposite of the prototype one would need to alleviate the Hubble tension locally (e.g. a void) - in other words, if one accounts for Laniakea’s impact on distances when inferring the Hubble constant locally, one should find an even higher Hubble constant, by an amount which we quantify exactly. Congratulations to Leo, who did basically all the heavy-lifting on this paper (incidentally this is what we were working on when he visited), which I expect can become a very important one! You can read our results in the preprint we just posted on arXiv: 2311.00215.
