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Experimental Particle and Astro-Particle Physics Seminar
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Europe/Zurich
Description
Abstract: In this talk I will discuss the Peak Sirens method, a new technique for reconstructing the Hubble diagram from gravitational wave (GW) observations and galaxy surveys. For most GW events, the biggest challenge in measuring the Hubble constant is the lack of redshift information from GW data. This has to be indirectly inferred from additional data sets or assumptions on properties of compact objects, such as their mass distribution. In the Peak Sirens method one instead statistically infers the redshifts of dark standard sirens through the peak of their 3D angular cross-correlations with galaxies, with little astrophysical entanglement. We will see that this new observable quantifies the matching of two large-scale structures observed in different radial coordinates; while galaxies are observed in redshift space, only the luminosity distances to GW sources are known. I will discuss the method, and then present our recent work where we detected for the first time those cross-correlations, at 5.9$\sigma$, with GWTC-3 and the GLADE+ catalogs. We obtained the first measurement of the Hubble constant from this method, and the first bounds whatsoever on the gravitational wave clustering bias. These results open a new window for analysing GW sources as tracers of the large scale structures, showing this can be done before the 3g era.