Mainz-Frankfurt CosmoCoffee

Contribution List

1. Welcome

Laura Sagunski

26/11/2021, 14:00

6. Kai Schmitz (CERN), "Pulsar hints for nanohertz gravitational waves?"

Kai Schmitz (CERN)

26/11/2021, 14:15

All major pulsar timing array (PTA) collaborations---NANOGrav, Parkes PTA, and EPTA---are now seeing indications of a new stochastic process in their latest data sets. If confirmed in the future, this new signal may turn out to be the first glimpse of a stochastic gravitational-wave background at nanohertz frequencies. In this talk, I will review how PTAs search for gravitational waves,...

5. Wolfram Ratzinger (Mainz), "Axion fragmentation on the Lattice"

Wolfram Ratzinger (Johannes Gutenberg Universität Mainz)

26/11/2021, 15:30

Recently scenarios in which an initially homogeneous field rolls over an oscillatory potential have been popularized by variations of the relaxion mechanism as well as the kinetic misalignment scenario for ALPs. These systems possess an instability that leads to the kinetic energy in the homogeneous field getting transferred to exponentially enhanced fluctuations. I will present a detailed...

3. Stephan Wystub (Frankfurt), "Constraining exotic compact stars composed of bosonic and fermionic dark matter with gravitational wave events"

Stephan Wystub

26/11/2021, 16:00

We investigate neutron star-black hole (NS-BH) merger candidates as a test for compact exotic objects. Using the events GW190814, GW200105 and GW200115 measured by the LIGO-Virgo collabration, which represent a broad profile of the masses in the NS mass spectrum, we demonstrate the constraining power for the parameter spaces of compact stars consisting of dark matter for future measurements.

4. Niklas Becker (Frankfurt), "Intermediate Mass Ratio Inspirals in Dark Matter Spikes"

Niklas Becker

26/11/2021, 17:00

To test the particle nature of dark matter, its influence on the inspiral of stellar mass black holes onto intermediate mass black holes (IMBHs) can be studied. If the IMBH forms an adiabatic dark matter spike around it, the smaller black hole will gravitationally interact with and accrete the dark matter particles. Thus, the dark matter spike can be studied and mapped out with the...

2. Nicklas Ramberg (Mainz), "QCD Axion Kinetic Misalignment Observational Aspects"

Nicklas Ramberg

26/11/2021, 17:30

When the spontaneous breaking of the Peccei-Quinn (PQ) symmetry occurred, the resulting angular direction of the PQ field, i.e.\ the axion could have possessed an initial non-zero velocity arising from additional terms that explicitly break the PQ symmetry. I elaborate further on the outcome of the "kinetic misalignment'' framework, assuming that axions form the entirety of the dark matter...