Synergy of LISA and ET Enhances Gravitational Wave Detection

Recent research by Alisha Marriott-Best, Debika Chowdhury, Anish Ghoshal, and Gianmassimo Tasinato explores the potential of combining the gravitational wave (GW) detectors LISA (Laser Interferometer Space Antenna) and ET (Einstein Telescope) to enhance the detection of cosmological gravitational wave backgrounds (SGWB). The paper, titled "Exploring cosmological gravitational wave backgrounds through the synergy of LISA and ET," was submitted on September 4, 2024, and is available on arXiv under the identifier 2409.02886.

The study highlights that LISA and ET will operate across different frequency ranges but possess similar sensitivities to the amplitude of SGWB. By analyzing various sources of SGWB, including those from cosmological phase transitions and cosmic strings, the authors demonstrate that the two detectors working in tandem can provide a more comprehensive understanding of the gravitational wave spectrum produced by the same cosmological events.

One significant aspect of their findings is the ability of LISA and ET to detect features of early universe cosmic expansion that occurred before big-bang nucleosynthesis (BBN). This capability is crucial as it allows scientists to probe different epochs of the universe's history, which would be challenging to achieve with a single detector. Additionally, the research includes a preliminary analysis of the sensitivity of both instruments to higher-order tensor correlation functions, which can yield insights into the nature of gravitational waves that cannot be captured by individual detectors alone.

The implications of this research are substantial, as it could lead to a deeper understanding of the universe's formation and evolution, particularly regarding the events that shaped its early stages. The collaboration between LISA and ET represents a significant advancement in gravitational wave astronomy, potentially opening new avenues for discovery in cosmology.