High-Precision Timing of 5 Millisecond Pulsars: Space Velocities, Binary Evolution and Equivalence Principles

TL;DR

This study presents high-precision timing of five millisecond pulsars over seven years, measuring their velocities, binary parameters, and testing fundamental physics principles like the equivalence principle and Lorentz invariance.

Contribution

It provides new measurements of pulsar velocities, binary parameters, and updated limits on violations of fundamental physics principles, enhancing understanding of pulsar evolution and fundamental physics.

Findings

Pulsar velocities range from 70-210 km/s, consistent with other MSPs.

Velocity distributions of isolated and binary MSPs are statistically indistinguishable.

New constraints on violations of the strong equivalence principle and Lorentz invariance.

Abstract

We present high-precision timing of five millisecond pulsars (MSPs) carried out for more than seven years; four pulsars are in binary systems and one is isolated. We are able to measure the pulsars' proper motions and derive an estimate for their space velocities. The measured two-dimensional velocities are in the range 70-210 km/s, consistent with those measured for other MSPs. We also use all the available proper motion information for isolated and binary MSPs to update the known velocity distribution for these populations. As found by earlier works, we find that the velocity distribution of binary and isolated MSPs are indistinguishable with the current data. Four of the pulsars in our observing program are highly recycled with low-mass white dwarf companions and we are able to derive accurate binary parameters for these systems. For three of these binary systems we are able to place initial constraints on the pulsar masses with best-fit values in the range 1.0-1.6 M_sun. The implications of the results presented here to our understanding of binary pulsar evolution are discussed. The updated parameters for the binary systems studied here, together with recently discovered similar systems, allowed us to update previous limits on the the violation of the strong equivalence principle through the parameter |Delta| to 4.6x10^-3 (95% confidence) and the violation of Lorentz-invariance/momentum-conservation through the parameter |hat{alpha}_3| to 5.5x10^-20 (95% confidence).