7th BIG Meeting: Barcelona Initiative for Gravitation

Friday 7 Nov 2025, 11:40 → 18:30 Europe/Madrid

V12M (UB Physics Faculty)

 

The BIG meetings aim to bring together all actors working in the field of gravity and cosmology in Barcelona, from observations to theory. 

These series of meetings has the purpose to set an informal stage for the exchange of ideas and to encourage joint discussions on relevant topics in the field.  It also provides the opportunity for people working in Barcelona to get informed on the lines of research of the other institutes.

Organizers

Diego Blas (IFAE), Jacopo Fumagalli (ICCUB), Jaume Garriga (ICCUB), Sascha Husa (ICE-CSIC), Oriol Pujolas (IFAE), Carlos Sopuerta (ICE-CSIC)

11:40 → 12:00 Welcoming & Writing and reading papers in the era of LLM: food for thought

Speaker: Licia Verde (ICCUB)

WelcomeBIG.pdf

12:00 → 13:00 Inflation without an inflaton

In the inflation without inflaton scenario (IWI) there are no free parameters as the energy scale for inflation is determined by the observed value of the initial scalar perturbations by the cosmic microwave background. In this talk we will describe the scenario and show new advances in the computation of observational signals like non-gaussianity

Speakers: Mariam Abdelaziz (ICCUB), Marisol Traforetti (ICCUB), Raul Jimenez (ICCUB)

Inflation_Without_Inflaton.pdf

13:00 → 14:45 Lunch

14:45 → 15:30 Search for high frequency gravitational waves with electromagnetic cavities

Recently, there has been a great interest in searching for gravitational waves with frequencies much higher than the realm of current ground based detectors, typically in the MHz-GHz range. For the most part, the signals expected in this frequency range would be signs of physics beyond the Standard Model. Among many experimental possibilities, one promising way of detection relies on the use of electromagnetic cavities. In this talk, I will review the various effects of GW on cavities and I will discuss the current progress on the modeling of the full response of the cavity to GW

Speaker: Jordan Gué (IFAE)

jg_BIG.pdf

15:30 → 15:45 Break

15:45 → 16:15 Higher-dimensional black holes in a cosmological context

Motivated by many interesting features present in braneworld cosmology and higher-dimensional gravity, we reexamine foundational concepts and processes that have previously been studied in this framework, such as gravitational collapse, black hole accretion and Hawking emission. In this talk we delve into these processes in a cosmological context and into the possibility of the totality of dark matter being in the form of higher-dimensional black holes formed in the Early Universe

Speaker: Itzi Aldecoa-Tamayo (University of Sussex)

Slides-BIG-meeting-nov25.pdf

16:15 → 16:45 Discussion - Break

16:45 → 17:30 Waveform modeling in Gravitational-Wave astronomy: achievements, systematics, and future challenges

Gravitational-wave astronomy has entered a mature observational era, with the latest Gravitational-Wave Transient Catalog (GWTC-4) reporting nearly a hundred new compact binary coalescences. These results rely critically on accurate waveform models to infer source properties and test general relativity. I will begin by reviewing how waveform models underpin current gravitational-wave analyses and by discussing recent results that reveal their limitations, such as the event GW231123. I will then present our recent work quantifying how systematic biases arising from inaccurate waveform models can affect key science goals of current and future observatories. Motivated by these challenges, I will discuss ongoing efforts to improve waveform accuracy through the inclusion of previously missing physical effects, such as equatorial-asymmetric emission and eccentric dynamics, and highlight the gains achieved so far. I will conclude with a discussion of the challenges that next-generation detectors will pose for waveform modeling, and possible avenues to address them.

Speaker: Hector Estelles (ICE-CSIC)

big_talk_waveforms_v3.pdf

17:30 → 17:45 Break

17:45 → 18:15 Gravitational Waves as a Probe of the Early Universe

Gravitational waves (GWs) provide a unique probe of the early universe, as they can travel almost freely from their generation to the present. I will discuss two cosmological GW sources: primordial GWs from quantum fluctuations during inflation and scalar-induced GWs (SIGWs) produced by curvature perturbations at horizon reentry. Both can reveal the universe’s thermal history. In particular, I will highlight how a non-standard reheating phase imprints distinctive features on the GW spectrum, and how the Big Bang nucleosynthesis (BBN) bound constrains the high-frequency tail of primordial GWs. I will also discuss the recent pulsar timing array (PTA) results and their possible interpretation as SIGWs, which may shed light on early-universe dynamics. Finally, I will briefly address the gauge issue of SIGWs and describe how to define a gauge-invariant observable by constructing a generalized idealized detector including second-order effects.

Speaker: Ao Wang (Leibniz U. and ITP, Beijing)

Ao Wang.pdf