Table 3.
Summary of observational upper limits (UP) and common spectrum process (CSP) amplitudes from PPTA (Shannon et al. 2015; Goncharov et al. 2021), NANOGrav (Arzoumanian et al. 2018, 2020), and EPTA (Babak et al. 2016; Chen et al. 2021).
| PPTA | NANOGrav | EPTA | SHARK | |
|---|---|---|---|---|
| UP | 1.0 × 10−15 | 1.45 × 10−15 | < 10−14 | |
| 10−16 − 10−15 | ||||
| CSP | 2.2 × 10−15 | 1.9 × 10−15 | 2.95 × 10−15 |
Notes. Last column shows mean amplitudes averaged over all SHARK models (range corresponds to 100 Myr and 1 Gyr coalescence times). Each value is referenced to the frequency of 1/yr.
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