Find Paper, Faster
Example:10.1021/acsami.1c06204 or Chem. Rev., 2007, 107, 2411-2502
Ultra-low-frequency gravitational waves from cosmological and astrophysical processes
Nature Astronomy  (IF14.437),  Pub Date : 2021-10-18, DOI: 10.1038/s41550-021-01489-8
Christopher J. Moore, Alberto Vecchio

Gravitational waves at ultra-low frequencies (100 nHz) are key to understanding the assembly and evolution of astrophysical black hole binaries with masses ~106–109M at low redshifts1,2,3. These gravitational waves also offer a unique window into a wide variety of cosmological processes4,5,6,7,8,9,10,11. Pulsar timing arrays12,13,14 are beginning to measure15 this stochastic signal at ~1–100 nHz and the combination of data from several arrays16,17,18,19 is expected to confirm a detection in the next few years20. The dominant physical processes generating gravitational radiation at nHz frequencies are still uncertain. Pulsar timing array observations alone are currently unable21 to distinguish a binary black hole astrophysical foreground22 from a cosmological background due to, say, a first-order phase transition at a temperature ~1–100 MeV in a weakly interacting dark sector8,9,10,11. This letter explores the extent to which incorporating integrated bounds on the ultra-low-frequency gravitational wave spectrum from any combination of cosmic microwave background23,24, big bang nucleosynethesis25,26 or astrometric27,28 observations can help to break this degeneracy.