Searching for continuous gravitational waves in the Parkes Pulsar Timing Array Data Release 3

TL;DR

This study conducted an all-sky search for continuous gravitational waves from supermassive binary black holes using PPTA DR3 data, setting new upper limits and improving sensitivity over previous searches, but found no evidence of such waves.

Contribution

The paper presents the most sensitive search to date for continuous gravitational waves in the 1-200 nHz band using PPTA DR3 data, with improved upper limits and analysis methods.

Findings

No evidence of continuous gravitational waves was detected.

Set a 95% upper limit of approximately 7 x 10^-15 on strain amplitude around 10 nHz.

Achieved at least 4 times better sensitivity than previous PPTA data release.

Abstract

We present results from an all-sky search for continuous gravitational waves from individual supermassive binary black holes using the third data release (DR3) of the Parkes Pulsar Timing Array (PPTA). Even though we recover a common-spectrum stochastic process, potentially induced by a nanohertz gravitational wave background, we find no evidence of continuous waves. Therefore, we place upper limits on the gravitational-wave strain amplitude: in the most sensitive frequency range around 10 nHz, we obtain a sky-averaged 95\% credibility upper limit of $\approx 7 \times 10^{-15}$. Our search is sensitive to supermassive binary black holes with a chirp mass of $\geq 10^9M_{\odot}$ up to a luminosity distance of 50 Mpc for our least sensitive sky direction and 200 Mpc for the most sensitive direction. This work provides at least 4 times better sensitivity in the 1-200 nHz frequency band than our last search based on the PPTA's first data release. We expect that PPTA will continue to play a key role in detecting continuous gravitational waves in the exciting era of nanohertz gravitational wave astronomy.