Présidents de session
Invited talk: Updates from the fourth release of the Gravitational Wave Transient Catalog (GWTC-4) and latest results from the search for an Isotropic Gravitational-Wave Background from the first part of LIGO, Virgo, and KAGRA's fourth Observing Run (O4a).
- Alba Romero-Rodríguez (Laboratoire d'Annecy de Physique de Particules (LAPP))
Description
In this talk, I present the latest results from the fourth release of the Gravitational Wave Transient Catalog (GWTC-4) and the search for an isotropic Gravitational-Wave Background (GWB) using data from the first part of LIGO, Virgo, and KAGRA’s fourth observing run (O4a). GWTC-4 includes 128 new compact binary coalescence (CBC) candidates, consistent with binary black holes and binary neutron stars, bringing the total to 218, including several detections with SNR > 30. Regarding the GWB, although no evidence for a signal is found, we set improved constraints on several theoretical models. For compact binaries with a 2/3 power-law spectrum, we improve limits on the fractional energy density by a factor of 1.7; for scale-invariant backgrounds, sensitivity improves by a factor of 2.1. New bounds are also placed on non-standard polarization modes. Combining these limits with GWTC-4 population models, constraints remain above the predicted merger background. Using GWTC-4 inference and standard modeling assumptions, we estimate that the total CBC background could be detectable with A+ sensitivity.
