Advancing gravitational wave predictions from cosmological first-order phase transitions

Session

Macroscopic scales

28 Aug 2025, 09:15

4/3-006 - TH Conference Room (CERN)

Conveners

Macroscopic scales: Morning session

• Hyun Min Lee

Macroscopic scales: Morning session

• Hyun Min Lee

Macroscopic scales: Afternoon session

• Simona Procacci (University of Geneva (CH))

Macroscopic scales: Short talks

• Alberto Roper Pol

Macroscopic scales: Morning session

• Seong Chan Park

Macroscopic scales: Panel Discussion

• Alberto Roper Pol

Description

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Presentation materials

discussion_macroscopic_scales_results.pdf

28. Strong phase transitions and gravitational waves

Thomas Konstandin

28/08/2025, 09:15

29. Pulsar Timing Arrays Data in the View of Early Universe Physics

Tina Kakhniashvili

28/08/2025, 10:30

Recent detection of stochastic gravitational wave background by pulsar timing arrays (PTAs) missions opens a new window of testing fundamental physics laws at energy scales far beyond what is reached by particle physics experiments and/or by astrophysical observations; In my talks I will addresses such early-universe sources as primordial hydro and magnetic turbulence which are possibly...

30. Acoustic fluid perturbations in first-order phase transitions

Antonino Salvino Midiri (Universite de Geneve (CH))

28/08/2025, 11:15

We study the irrotational velocity spectra induced in a fluid during a first-order phase transition in the radiation-dominated era. Interactions of the scalar broken-phase bubbles with the fluid generate irrotational velocity and enthalpy profiles which are, together with the statistical time distribution of bubble nucleation and collision, predictive of the gravitational wave spectrum...

32. Cosmological first-order phase transitions with large bubbles: beyond conformal fluid and flat spacetime

Lorenzo Giombi (University of Helsinki)

28/08/2025, 13:30

Using semi-analytical models, we investigate the power spectrum of gravitational waves generated by sound waves in the plasma during a first-order phase transition in new unexplored scenarios. (i) The phase transition is accompanied by a change of the equation of state from that of pure radiation. This causes the peak of the spectrum to shift to smaller frequencies as the equation of state...

15. Decay of acoustic turbulence and the resulting gravitational wave predictions

Jani Dahl

28/08/2025, 14:15

Macroscopic scales

For a wide range of scenarios, the generation of gravitational waves (GWs) from cosmological first-order phase transitions is believed to be dominated by sound waves. Understanding their decay through acoustic turbulence is an important factor in determining the overall intensity of the GW signal. We have simulated acoustic turbulence numerically in three dimensions to study its decay...

18. Exploring Parameter Dependence in the Double-Broken Power Law for GW Signals

Eric Madge Pimentel (IFT-UAM/CSIC)

28/08/2025, 15:30

The gravitational wave spectrum from sound wave contributions is typically modeled as a double-broken power law with fixed spectral slopes. However, the intermediate slope depends on phase transition parameters, which can help resolve degeneracies when reconstructing these parameters. To improve gravitational wave predictions, we provide an analytic form of this parameter dependence, derived...

5. The complicated story of Primordial Black Holes production in cosmological Phase Transitions

Piotr Toczek (University of Warsaw)

28/08/2025, 15:35

In this talk, I will investigate the formation of Primordial Black Holes as the result of the collapse of energy density fluctuations originating from supercooled first-order phase transitions. I will present the results of a simplified approach, where the energy density fluctuations are evolved within the limit of flat FRW Universe. I will show how energy density fluctuations modify the...

17. From equations of state to gravitational wave spectra

Mika Mäki

28/08/2025, 15:40

The Sound Shell Model provides a computationally efficient way of calculating the gravitational wave spectra of cosmological first-order phase transitions. Based on the Sound Shell Model, we have created the simulation framework PTtools and integrated it with our web-based plotting utility PTPlot.

In this talk I will show how to use PTtools and PTPlot to easily compute Sound Shell Model...

34. Gravitational wave production: the interplay between vortical and compressional motions

Madeline Clara Salome (Universite de Geneve (CH))

28/08/2025, 15:45

In the early Universe, during a phase transition, the surrounding plasma is subjected to a fluid motion sourcing gravitational waves. This fluid motion can be composed of compressional and vortical motions. Most of the time, they are considered distinct and studied independently. However, by analyzing the UETC of the anisotropic stresses, a mixed term combining vortical and compressional...

13. GW fingerprints of inverse FOPTs

Giulio Barni

28/08/2025, 15:50

Building upon the recently proposed concept of inverse FOPT, we investigate their GW signatures. We outline how these transitions differ thermodynamically and hydrodynamically from standard ones and analyse the resulting GW emission from the plasma.

Adopting the bag equation of state as a minimal setup, we compute self-similar fluid profiles over a range of wall velocities and transition...

21. Curvature perturbation from first-order phase transitions & A positive-definite formulation of tunneling

Ryusuke Jinno (Kobe University)

29/08/2025, 09:15

This talk is consists of two parts. In the first part I will talk about curvature perturbation produced in very strong first-order phase transitions. I will first explain super-hubble curvature perturbation based on 2311.16222, and then move on to hubble-scale curvature perturbation based on 2503.01962. In the second part I change the topic and talk about a new type of formulation of quantum...