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New Limits on Gravitational Radiation using Pulsars

A. N. Lommen

TL;DR

The paper reports a 17-year, multi-telescope PTA analysis of three millisecond pulsars to constrain the stochastic gravitational-wave background, achieving a GW energy-density limit of $\Omega_g h^2 \lesssim 2 \times 10^{-9}$. It introduces a robust method for combining heterogeneous timing data, uses orthogonal-polynomial spectral estimators to bound GW signals, and applies a Neyman-Pearson framework to derive limits. The work also updates timing-noise characterizations for MSPs, assesses terrestrial-time versus pulsar-clock stability, and explores a tentative planetary companion to PSR B1937+21 that could explain a cubic residual. Overall, the results strengthen PTA prospects for GW detection while highlighting intriguing astrophysical hints and the need for extended baselines.

Abstract

We calculate a new gravitational wave background limit using timing residuals from PSRs J1713+0747, B1855+09, and B1937+21. The new limit is based on 17 years of continuous data pieced together from 3 different observing projects: 2 at the Arecibo Observatory and 1 at the 140ft Green Bank Telescope. This project represents the earliest results from the `Pulsar Timing Array' which will soon be able detect the stochastic background from early massive black hole mergers.

New Limits on Gravitational Radiation using Pulsars

TL;DR

The paper reports a 17-year, multi-telescope PTA analysis of three millisecond pulsars to constrain the stochastic gravitational-wave background, achieving a GW energy-density limit of . It introduces a robust method for combining heterogeneous timing data, uses orthogonal-polynomial spectral estimators to bound GW signals, and applies a Neyman-Pearson framework to derive limits. The work also updates timing-noise characterizations for MSPs, assesses terrestrial-time versus pulsar-clock stability, and explores a tentative planetary companion to PSR B1937+21 that could explain a cubic residual. Overall, the results strengthen PTA prospects for GW detection while highlighting intriguing astrophysical hints and the need for extended baselines.

Abstract

We calculate a new gravitational wave background limit using timing residuals from PSRs J1713+0747, B1855+09, and B1937+21. The new limit is based on 17 years of continuous data pieced together from 3 different observing projects: 2 at the Arecibo Observatory and 1 at the 140ft Green Bank Telescope. This project represents the earliest results from the `Pulsar Timing Array' which will soon be able detect the stochastic background from early massive black hole mergers.

Paper Structure

This paper contains 10 sections, 17 equations, 11 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Observations
  3. Analysis
  4. Connection of Data Sets
  5. Limit on Gravitational Radiation
  6. Fractional Stability of Terrestrial Atomic Time Standards vs. Fractional Stability of Neutron Star Rotations
  7. Update on Timing Noise as a Function of Period Derivative
  8. Planet Around PSR B1937+21?
  9. Implications of Planet on Possible Evolutionary Scenarios of PSR B1937+21
  10. Conclusion

Figures (11)

  • Figure 1: (a) PSR J1713+0747, (b) PSR B1855+09, (c) PSR B1937+21 and (d) PSR B1937+21 fit for $\ddot{P}$. The open circles are KTR94 data, the filled circles are Green Bank data, and the open diamonds are ABPP data.
  • Figure 2: $\log{S_m}$ vs frequency index. Solid line shows measured values for each pulsar. Dotted lines show simulated data for spectral index 0. Dashed lines show simulated data for spectral indices 2, 3, and 5. (a) PSR J1713+0747, (b) PSR B1855+09, and (c) PSR B1937+21. Frequencies corresponding to frequency index are m/L where L is the length of the data set: (a) 9.2 yr, (b) 15.6 yr, and (c) 16.8 yr.
  • Figure 3: An example of two different probability density distributions. 5% of the area under the solid curve is to the left of the dotted line.
  • Figure 4: The solid line shows the probability density of the null statistic, S0, while the dashed curve shows the probability density of the S1 statistic at the 95% confidence value. The dotted line is the same as in Figure \ref{['fig:thorsett_example']}
  • Figure 5: Residuals from B1937+21 with no $\ddot{\nu}$ removed, fitted only to the range of the J1713+0747 data.
  • ...and 6 more figures