Loeb

Recently, there had been renewed interest in limiting the interaction between dark matter particles and known particles. I propose a new way to set upper limits on the coupling of ions or electrons to dark matter particles of arbitrary mass, based on Faraday's Law in a spinning conductor.

Ali Rida Khalifeh, Raul Jimenez

The tension between late and early universe probes of today's expansion rate, the Hubble parameter $H_0$, remains a challenge for the standard model of cosmology $\Lambda$CDM. There are many theoretical proposals to remove the tension, with work still needed on that front. However, by looking at new probes of the $H_0$ parameter one can get new insights that might ease the tension. Here, we argue that neutrino oscillations could be such a probe. We expand on previous work and study the full three-flavor neutrino oscillations within the $\Lambda$CDM paradigm. We show how the oscillation probabilities evolve differently with redshift for different values of $H_0$ and neutrino mass hierarchies. We also point out how this affects neutrino fluxes which, from their measurements at neutrino telescopes, would determine which value of $H_0$ is probed by this technique, thus establishing the aforementioned aim.

Emery Trott, Dragan Huterer

Gravitational waves (GW) can be employed as standard sirens that will soon measure the Hubble constant with sufficient precision to weigh in on the $\sim 5\sigma$ Hubble tension. Most GW sources will have no identified electromagnetic counterpart, leading to uncertainty in the redshift of the source, and in turn a degeneracy between host galaxy distance, redshift, and $H_0$. In the case where no electromagnetic counterparts are identified, it has been proposed that a statistical canvassing of candidate GW hosts, found in a large galaxy survey for example, can be used to accurately constrain the Hubble constant. We study and simulate this "galaxy voting" method to compute $H_0$. We find that the Hubble constant posterior is in general biased relative to the true value even when making optimistic assumptions about the statistical properties of the sample. This bias is caused by the fundamental degeneracy between redshift and $H_0$, and is effectively irreducible without accurate information about the redshift distribution from which the GW sources come.