Understanding the gravitational wave background: pulsar timing arrays and skymapping

Abstract:
In June 2023, members of the International Pulsar Timing Array (IPTA) released coordinated evidence for the gravitational wave background. In this seminar, I will explain how pulsar timing arrays measure the gravitational wave background and discuss the latest results from various arrays.

The MeerKAT radio telescope, one of the most sensitive in the world, has detected similar evidence after just 4.5 years of data collection through the MeerKAT Pulsar Timing Array. Thanks to its exceptional sensitivity and the new methods we have developed, we have produced the most accurate maps of the gravitational-wave background to date. I will discuss our advances in skymapping methods and results. Mapping is crucial for understanding the origin of this background, as an anisotropic background suggests supermassive black-hole binaries as the source. Notably, we identify a hotspot in the 7 nHz map with a p-value of 0.015.

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