COST Action Cosmic WISPers: Meetings of WG2 - Dark Matter and Cosmology

Contribution List

5. Axion Acoustic Misalignment Mechanism

Dr Raymond Co (Indiana U.)

09/05/2025

We established a paradigm where the (QCD) axion’s novel cosmological evolution, a rotation in field space, simultaneously accounts for the observed dark matter abundance and baryon asymmetry of the Universe: axion cogenesis. This rotation is initiated by explicit Peccei-Quinn (PQ) symmetry breaking active in the early Universe as predicted by quantum gravity. Through Standard Model sphaleron...

4. Diverse dark matter haloes in Two-field Fuzzy Dark Matter

Dr Nhan Luu Hoang (DIPC, San Sébastian)

19/06/2025

Fuzzy dark matter (FDM) is a compelling candidate for dark matter, offering a natural explanation for the structure of diffuse low-mass haloes. However, the canonical FDM model with a mass of $10^{-22}~{\rm eV}$ encounters challenges in reproducing the observed diversity of dwarf galaxies, except for scenarios where strong galactic feedback is invoked. The introduction of multiple-field FDM...

3. Experimental targets for dark photon dark matter

Dr David Cyncynates (U. Washington, Seattle)

29/11/2024

Ultralight dark photon dark matter features distinctive cosmological and astrophysical signatures and is also supported by a burgeoning direct-detection program searching for its kinetic mixing with the ordinary photon over a wide mass range. However, dark photons cannot necessarily constitute dark matter across all of this parameter space. In this talk, I will show that in minimal models...

2. Gravitational wave signatures of dark matter around binary black holes

Dr Josu Aurrekoetxea (MIT)

07/03/2025

Some of the most well-motivated extensions of the Standard Model of particle physics introduce light scalar fields to explain the origin of dark matter. These fields interact with black holes and can alter the gravitational waveforms produced by binary merger events. In this talk, I will discuss the use of numerical relativity simulations to study these signatures.

[Based on...

6. Impact of Adiabatic Fluctuations on the Power Spectrum of Axion Density Perturbations

Dr Ahmed Ayad (Bielefeld University)

02/10/2025

1. New avenues to probe Fuzzy Dark Matter

Juan Urrutia (KBFI, Tallinn)

31/01/2025

Based on two different effects that FDM produces on DM halos, making a core at the center and preventing the formation of very light ones. I will show constraints and propose new avenues based on new observations and techniques to probe the ultralight end of the DM mass