4th Meeting on Gravitational Wave Science in Denmark-Norway

23 May 2024, 12:00 → 24 May 2024, 14:05 Europe/Oslo

KE A-204

The meeting aims to bring together researchers working in gravitational wave science and related areas. This is the fourth meeting in the series and the first to be hosted in Norway. The third meeting was hosted in Aalborg in 2023. The format is very informal as usual, and similar to previous meetings there will be several short talks from researchers to summarize current activities.

Thursday, 23 May

12:50 → 13:00 Welcome

13:00 → 13:30 Measuring first-order phase transitions at LISA

The LISA mission has been adopted, with launch scheduled in 2035. This leaves us with just a decade to complete the data analysis pipelines and prepare the science interpretation of the potentially observed signals. In this talk we will briefly review the status of the mission, some possible data analysis approaches to isolate the primordial stochastic GW background (SGWB), and some potential bounds on BSM models predicting first-order phase transitions.

Speaker: Germano Nardini (UiS TN IMF)

13:30 → 14:00 Studying first-order phase transitions numerically

Speaker: Anders Tranberg (UiS - TN - IMF)

14:00 → 14:30 Cosmic redshift drift in gravitational waveforms

For a merger located at a constant redshift, the redshift of the merger is degenerate with the chirp mass of the system in the measured waveform. However, when the redshift can no longer be considered a constant over the duration of the merger in band, this degeneracy is broken. When the Universe undergoes accelerated expansion, the redshift to sources will grow in time, a signal that is in principle detectable in gravitational waveforms through a drift in the measured frequency of the system. The effect is tiny, however, since the expected frequency drift due to accelerated expansion is expected to be of order the Hubble constant for mergers at cosmological distances. It thus requires extremely precise measurements of gravitational waves to observe the drift, and the signal is a priori too small to be observed with the next generation of detectors. I am interested in ways of analysing waveforms that may amplify the signal.

Speaker: Asta Heinesen (Niels Bohr Institute)

14:30 → 15:00 Coffee break

15:00 → 15:30 Possible Causes of False General Relativity Violations in Gravitational Wave Observations

Speaker: Alex Nielsen

15:30 → 16:00 Looking for new physics beyond the merger of black holes

Black Holes are possibly the most enigmatic objects in our Universe. These cosmic enigmas continue to be active arenas for strong gravity and quantum effects, providing fertile ground for exploring elusive aspects of quantum gravity. Indeed, there are strong motivations for why Quantum black holes may be radically different from their classical counterparts in Einstein's General Relativity (GR). On the other side gravitational wave astronomy strives to experimentally verify the Kerr nature of black holes, presenting a critical avenue for testing this aspect observationally. Observing multiple Quasi Normal Modes (QNMs), also referred to as black hole spectroscopy, is one of the most robust tests under minimal additional assumptions. In this talk I will present my pioneer work looking for signatures of Hawking radiation along with black hole spectroscopy in gravitational wave data.

Speaker: Jahed Abedi (University of Stavanger)

16:00 → 16:30 Measuring deviations from Kerr using LVK ringdown data

According to the black hole no-hair theorem, the emitted ringdown spectra are constrained by the mass and spin of the remnant black hole and thus offer an excellent test of the Kerr-nature of black holes. As a parameterization of beyond-Kerr effects, we employ the Johannsen-Psaltis metric ansatz and analyze the ringdown of two binary black hole merger events- GW150914 and GW190521 to constrain the deviation from Kerr. We find improvement in constraints on the deviation parameter in the case of GW190521 as compared to GW150914.

Speaker: Zaryab Ahmed (Universitetet i Stavanger)

16:30 → 17:00 Contributed talks

19:00 → 20:30 Social dinner

Friday, 24 May

09:30 → 10:00 Gravitational waves from a non-abelian dark sector coupled to axion inflation

Taking axion inflation as an example, we study the evolution of a non-Abelian dark sector coupled to the inflaton for different choices of the confinement scale. For confinement scales just a few orders of magnitude below the Planck scale, large temperatures are reached in the dark sector and gravitational wave signal could be generated due to fluctuations in the thermal plasma. Another possible source of gravitational waves is the confinement phase transition; however, this signal might be strongly suppressed due to the presence of an early matter-dominated era.

Speaker: Helena Kolesova (University of Stavanger)

10:00 → 11:00 Contributed talks

11:00 → 11:30 Coffee break

11:30 → 12:00 Gravitational waves and the work of Aleksi Kurkela

Speaker: Aleksi Kurkela (Univ. Stavanger)

12:00 → 12:30 Gravitational waves and the work of Oleg Komoltsev

Speaker: Oleg Komoltsev (University of Stavanger)

12:30 → 13:00 Contributed talks

13:00 → 13:10 Closing