Phenomenology 2022 Symposium: From Virtual to Real

Session

Cosmology II

9 May 2022, 16:30

Lawrence Hall 107

Conveners

Cosmology II

• Fei Huang (ITP CAS and UC Irvine)

36. Cosmologically Degenerate Fermions

Ms Ying-Ying Li (Fermilab)

09/05/2022, 16:30

Even in the total absence of thermal kinetic energy, fermionic dark matter must have nonzero momentum due to the Pauli degeneracy pressure. As the fermions were inevitably denser at higher redshifts, a typical fermion may gain a fermi momentum that can exceed its mass. I will talk about the impacts of the transition between nonrelativistic and relativistic behaviour, as revealed by...

77. Thermal Friction as a Solution to the Hubble and Large-Scale Structure Tensions

Kim Berghaus (Johns Hopkins University)

09/05/2022, 16:45

Thermal friction offers a promising solution to the Hubble and the large-scale structure (LSS) tensions. This additional friction acts on a scalar field in the early universe and extracts its energy density into dark radiation, the cumulative effect being similar to that of an early dark energy (EDE) scenario. The dark radiation automatically redshifts at the minimal necessary rate to improve...

28. New developments in the Galactic Center Gamma-Ray Excess

Yiming Zhong (University of Chicago)

09/05/2022, 17:00

The Galactic center gamma-ray excess (GCE) remains one of the most intriguing discoveries from the Fermi Large Area Telescope (Fermi-LAT) observations. Explanations of the GCE include a new population of millisecond pulsars, or annihilating dark matter. The latter explanation could provide us with the first evidence for dark matter interacts with the Standard Model. Debates over the GCE origin...

52. BBN Constraints on Gravitationally Produced Dark Photons

Moinul Rahat

09/05/2022, 17:15

Dark photons can be gravitationally produced from quantum fluctuations during inflation, and it can be more efficient compared to the freeze-in production. The decay of the dark photons around BBN would inject electromagnetic energy into the plasma and potentially disrupt the successful prediction of light element abundances by BBN. In this talk I will discuss MeV to GeV scale gravitationally...

30. Finding Evidence for Inflation and the Origin of Galactic Magnetic Fields with CMB Surveys

Sayan Mandal

09/05/2022, 17:30

The origin of the microgauss magnetic fields observed in galaxies is unknown. One scenario is that primordial magnetic fields (PMFs) generated during inflation, larger than 0.1 nanogauss on Mpc scales, were compressed to microgauss strengths in galaxies during structure formation. Thus, detecting such a PMF just after recombination would be evidence of this inflationary origin. We find that...

47. Bound on Quantum Gravitational Wave Fluctuations from LIGO

Jacob Litterer

09/05/2022, 17:45

Gravitational wave observations at LIGO are in good agreement with classical predictions, with a residual that does not exhibit any unexplained correlations. In the context of general relativity as an effective quantum theory, gravitational waves have been thought to be in the most classical coherent state, in which quantum fluctuations are far too small to see at LIGO. Alternatively, it is...

46. Cosmological Constraints on First-Order Phase Transitions

Mrunal Korwar

09/05/2022, 18:00

First-order phase transitions exist in many models beyond the Standard Model and can generate detectable stochastic gravitational waves for a strong one. Using the cosmological observables in big bang nucleosynthesis and cosmic microwave background, we derive constraints on the phase transition temperature and strength parameter in a model-independent way. For a strong phase transition, we...