Seminario Ruchika

Il giorno 16 aprile alle ore 11,30 presso l'aula 412, la Dott.ssa Ruchika (Università di Roma La Sapienza) terra' un seminario dal titolo

Reconciling HST, JWST and Planck

Abstract

In the era of precision cosmology, recent observations from missions like the Planck satellite and the SH0ES team using the Hubble Space Telescope (HST) have challenged the standard model of cosmology, ΛCDM. Notably, discrepancies in the measurement of the Hubble constant from cosmic microwave background (CMB) and local measurements using Cepheids and supernovae have emerged, suggesting potential shortcomings in our understanding of cosmology.
Additionally, discoveries from the James Webb Space Telescope (JWST) have unveiled a significant density of massive galaxies at high redshifts, posing further challenges to the ΛCDM. Despite conservative assumptions about galaxy formation, these findings may not align with any of the current cosmological models.
I will talk about cosmological tensions utilizing most of the cosmological probes from high, low, intermediate, and local redshifts along with various proposed solutions to these cosmological tensions and highlighting their limitations compared to the ΛCDM.
I will discuss about how important it is now to do critical reassessment of the basic assumptions of inverse distance ladder and standard distance ladder proposing solutions such as allowing possibility of new physics such as negative cosmological constant or G-transition hypothesis/ PLR break in cepheids.
Furthermore, while assuming ΛCDM and no systematics in the current JWST results, we propose that there may be an unknown systematic error in current large angular scale CMB polarization measurements, or new physics is required to explain the discrepancy.