Joint cosmology seminar at Tufts:

Tuesday, October 28, 2025, 2:30 pm
574 Boston Ave, Room 316\\
Tufts University
Refreshments at 2:00 outside room 304

Cosmic tension phenomenology

Tanvi Karwal
Chicago

Abstract:

My talk will begin by summarising key observables and their physical and parametric sensitivities. Using this framework, I will present my work dissecting the low S8 value from weak-lensing data and the DESI preferences for evolving dark energy and negative neutrino masses. Data from DESI, supernovae and the CMB are mildly discrepant on the LCDM value of Omega\_m, which can manifest as a preference for evolving dark energy, and my work finds that this preference for w0wa is not a prior-volume effect. On the neutrino side, freedom in the optical depth tau to reionisation, lensing amplitude A\_lens or w0wa dark energy can restore consistency between cosmology and terrestrial experiments on the sum of neutrino masses. Finally, I will present a new framework for a model-independent reconstruction of the scale-dependent matter power spectrum P(k) from lensing data. This can reveal the physical scales where the data prefer deviations from Planck LCDM. By mapping observables to the parameters they constrain and the scales they probe, we can see more clearly where LCDM continues to succeed, where it strains against the data, and how those stress points can guide the search for new physics.