Description
https://pitt.zoom.us/j/91379044495
Axion couplings to photons could induce photon-axion conversion in the presence of magnetic fields in the Universe. The conversion could impact various cosmic distance measurements such as luminosity distances to type Ia supernovae and angular distances to galaxy clusters in different ways. We consider different combinations of the most updated distance measurements to constrain the...
A number of proposed and ongoing experiments search for axion dark matter with a mass nearing the limit set by small scale structure. I will discuss the late universe cosmology of these models and show that requiring the axion to have a matter-power spectrum that matches that of cold dark matter constrains the magnitude of the axion couplings to the visible sector. I will also survey...
Ultralight axions (ULA), whose masses can lie in a wide range of values and can be even smaller than $10^{-28}$ eV, are generically predicted in UV theories such as string theory. In the cosmological context, the early Universe may have gotten filled with a network of ultralight axion (ULA) cosmic strings which, depending upon the mass of the axion, can survive till very late times. If the ULA...
Axion-like particles (ALPs) play an important role for inflationary model building, as well as are well motivated dark matter candidates. The out-of-equilibrium initial conditions, combined with their possibly nontrivial potentials, allow for a rich nonlinear dynamics of such fields in the early universe.
We consider the coherent oscillations of an ALP field in a wiggly potential and...
Axions, if they exist, can be produced efficiently in white dwarfs, free-stream out of the star due to their weak interactions with matter, and then be converted to a photon in the stellar magnetosphere. X-ray telescope observations of these stars can provide strong constraints on the coupling to electromagnetism and matter. I discuss the results of the first dedicated observation of a...
Neutrino self-interaction has been proposed as a solution to the Hubble tension, a discrepancy between the measured values of the Hubble constant from CMB and low-redshift data. However, flavor-universal neutrino self-interaction is highly constrained by BBN and laboratory experiments such as K-meson and tau decay, double-neutrino beta decay etc. In this talk, I will discuss the cosmology of...
If neutrino self-interactions arise from beyond-Standard Model physics, there will be scattering between astrophysical and cosmic background neutrinos. As a result, resonance features can appear in astrophysical neutrino spectra. While the flavor-diagonal case has been studied before numerically, we present an analytic result for arbitrary self-coupling matrix, allowing for possibilities such...
