Gravitational-wave constraints on the equatorial ellipticity of millisecond pulsars

TL;DR

This paper reports a search for continuous gravitational waves from five pulsars using LIGO and Virgo data, setting new constraints on their ellipticities and surpassing previous indirect limits for some pulsars.

Contribution

First to match or surpass indirect gravitational-wave emission limits for certain recycled pulsars, providing tighter constraints on their ellipticities.

Findings

Constraints on ellipticities less than 10^{-8} for some pulsars.

Matched or exceeded previous indirect limits for PSR J0437-4715 and PSR J0711-6830.

Set new upper limits on gravitational-wave emission from five pulsars.

Abstract

We present a search for continuous gravitational waves from five radio pulsars, comprising three recycled pulsars (PSR J0437-4715, PSR J0711-6830, and PSR J0737-3039A) and two young pulsars: the Crab pulsar (J0534+2200) and the Vela pulsar (J0835-4510). We use data from the third observing run of Advanced LIGO and Virgo combined with data from their first and second observing runs. For the first time we are able to match (for PSR J0437-4715) or surpass (for PSR J0711-6830) the indirect limits on gravitational-wave emission from recycled pulsars inferred from their observed spin-downs, and constrain their equatorial ellipticities to be less than $10^{-8}$. For each of the five pulsars, we perform targeted searches that assume a tight coupling between the gravitational-wave and electromagnetic signal phase evolution. We also present constraints on PSR J0711-6830, the Crab pulsar and the Vela pulsar from a search that relaxes this assumption, allowing the gravitational-wave signal to vary from the electromagnetic expectation within a narrow band of frequencies and frequency derivatives.