The stochastic gravitational wave background (SGWB) is a diffuse gravitational wave signal resulting from the superposition of numerous unresolved sources. The two main obstacles to the detection of the SGWB anisotropies are the poor angular resolution of gravitational wave detectors for a diffuse SGWB image and the presence of a significant contribution from gunshot noise. The first problem mainly has to do with the noise characteristics of the detector and how it projects onto the sky.

A new SISSA study proposes an array of interferometers in space to detect subtle fluctuations in the background gravity signal that could reveal the secrets of black hole mergers. Using a constellation of three or four space interferometers, scientists are about to map the flat and almost perfectly homogeneous background in a search for ripples.

Scientists call these small fluctuations anisotropies and contain the data needed to understand the distribution of gravitational wave sources on the largest cosmological scale.

Giulia Capurri, a SISSA Ph.D. student and first author of the study, said: “Measuring these background fluctuations, known as however, anisotropies will remain extremely difficult as identifying them requires a very high level of angular resolution not present in current and next generation research instruments.”

A “constellation” of three or four space interferometers placed in orbit around the Sun, covering an area roughly equal to the distance between the Earth and the Sun, could solve this problem. The ability of interferometers to distinguish gravitational wave sources improves with increasing separation due to improved angular resolution.

Capuri said, “A constellation of space interferometers orbiting the sun could allow us to see subtle fluctuations in the gravitational background signal, extracting valuable information about the distribution of black holes, neutron stars and all other sources.” of gravitational waves in the universe.”

Carlo Baccigalupi, professor of theoretical cosmology at SISSA, said: “Following the success of the LISA project space mission test, there are currently two proposals for creating space-based interferometer constellations: a European – the Big Bang Observatory (BBO) and a Japanese – the Deci-hertz Interferometer Gravitational-wave Observatory (DECIGO).”

“This represents one of the earliest works to make specific predictions about the size of the stochastic background of gravitational waves through a constellation of instruments orbiting the sun. Together with other similar projects, details of which will be published in due course, they will be crucial in developing an optimal design for future observing instruments that we hope will be built and commissioned in the coming decades.”

Magazine reference:

  1. Giulia Capurri, Andrea Lapi, Lumen Boco and Carlo Baccigalupi. Search for anisotropic stochastic gravitational wave backgrounds with constellations of space-based interferometers. The Astrophysical Journal. DOI 10.3847/1538-4357/acaaa3