Scalar induced gravitational waves in light of Pulsar Timing Array data

TL;DR

This paper investigates scalar induced gravitational waves (SIGWs) as a potential explanation for pulsar timing array data, showing they fit the observed signals better than supermassive black hole binaries and providing tentative evidence for their existence.

Contribution

The study tests the infrared part of SIGWs against pulsar timing array data, demonstrating a better fit than SMBHBs and offering new insights into the origin of the gravitational wave background.

Findings

Infrared SIGWs fit PTA data better than SMBHBs.

Bayesian analysis supports SIGWs as a plausible source.

Tentative evidence for the existence of SIGWs.

Abstract

The power-law parametrization for the energy density spectrum of gravitational wave (GW) background is a useful tool to study its physics and origin. While scalar induced secondary gravitational waves (SIGWs) from some particular models fit the signal detected by NANOGrav, Parkers Pulsar Timing Array, European Pulsar Timing Array, and Chinese Pulsar Timing Array collaborations better than GWs from supermassive black hole binaries (SMBHBs), we test the consistency of the data with the infrared part of SIGWs which is somewhat independent of models. Through Bayesian analysis, we show that the infrared parts of SIGWs fit the data better than GW background from SMBHBs. The results give tentative evidence for SIGWs.