scholarly journals Bayesian inference for pulsar-timing models

2014 ◽  
Vol 440 (2) ◽  
pp. 1446-1457 ◽  
Author(s):  
Sarah J. Vigeland ◽  
Michele Vallisneri
Keyword(s):  
Bayesian Inference ◽  
Pulsar Timing ◽  
Timing Models

scholarly journals Timing of young radio pulsars – I. Timing noise, periodic modulation, and proper motion

2019 ◽  
Vol 489 (3) ◽  
pp. 3810-3826 ◽  
Author(s):  
A Parthasarathy ◽  
R M Shannon ◽  
S Johnston ◽  
L Lentati ◽  
M Bailes ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Plasma Physics ◽  
Proper Motion ◽  
Noise Amplitude ◽  
Periodic Modulation ◽  
Proper Motions ◽  
Radio Pulsars ◽  
Arrival Times ◽  
Pulsar Timing ◽  
Timing Noise

ABSTRACT The smooth spin-down of young pulsars is perturbed by two non-deterministic phenomenon, glitches, and timing noise. Although the timing noise provides insights into nuclear and plasma physics at extreme densities, it acts as a barrier to high-precision pulsar timing experiments. An improved methodology based on the Bayesian inference is developed to simultaneously model the stochastic and deterministic parameters for a sample of 85 high-$\dot{E}$ radio pulsars observed for ∼10 yr with the 64-m Parkes radio telescope. Timing noise is known to be a red process and we develop a parametrization based on the red-noise amplitude (Ared) and spectral index (β). We measure the median Ared to be $-10.4^{+1.8}_{-1.7}$ yr3/2 and β to be $-5.2^{+3.0}_{-3.8}$ and show that the strength of timing noise scales proportionally to $\nu ^{1}|\dot{\nu }|^{-0.6\pm 0.1}$, where ν is the spin frequency of the pulsar and $\dot{\nu }$ is its spin-down rate. Finally, we measure significant braking indices for 19 pulsars and proper motions for 2 pulsars, and discuss the presence of periodic modulation in the arrival times of 5 pulsars.

scholarly journals Radio timing in a millisecond pulsar – extreme/intermediate mass ratio binary system

2020 ◽  
Vol 644 ◽  
pp. A167
Author(s):  
T. Kimpson ◽  
K. Wu ◽  
S. Zane
Keyword(s):  
Globular Clusters ◽  
Relativistic Effects ◽  
Propagation Delay ◽  
Higher Order ◽  
Galactic Centre ◽  
Millisecond Pulsar ◽  
Fundamental Physics ◽  
Timing Model ◽  
Pulsar Timing ◽  
Timing Models

Radio timing observations of a millisecond pulsar in orbit around the Galactic centre black hole (BH) or a BH at the centre of globular clusters could answer foundational questions in astrophysics and fundamental physics. Pulsar radio astronomy typically employs the post-Keplerian approximation to determine the system parameters. However, in the strong gravitational field around the central BH, higher order relativistic effects may become important. We compare the pulsar timing delays given by the post-Keplerian approximation with those given by a relativistic timing model. We find significant discrepancies between the solutions derived for the Einstein delay and the propagation delay (i.e. Roemer and Sharpiro delay) compared to the fully relativistic solutions. Correcting for these higher order relativistic effects is essential in order to construct accurate radio timing models for pulsar systems at the Galactic centre and the centre of globular clusters and informing issues related to their detection.

scholarly journals Pulsars Probe the Low-Frequency Gravitational Sky: Pulsar Timing Arrays Basics and Recent Results

2018 ◽  
Vol 35 ◽  
Author(s):  
Caterina Tiburzi
Keyword(s):  
Gravitational Waves ◽  
Galaxy Formation ◽  
Low Frequency ◽  
Radio Telescopes ◽  
Detection Algorithms ◽  
Pulsar Timing ◽  
Upper Limits ◽  
New Generation ◽  
Timing Models ◽  
Pulsar Timing Array

AbstractPulsar Timing Array experiments exploit the clock-like behaviour of an array of millisecond pulsars, with the goal of detecting low-frequency gravitational waves. Pulsar Timing Array experiments have been in operation over the last decade, led by groups in Europe, Australia, and North America. These experiments use the most sensitive radio telescopes in the world, extremely precise pulsar timing models and sophisticated detection algorithms to increase the sensitivity of Pulsar Timing Arrays. No detection of gravitational waves has been made to date with this technique, but Pulsar Timing Array upper limits already contributed to rule out some models of galaxy formation. Moreover, a new generation of radio telescopes, such as the Five hundred metre Aperture Spherical Telescope and, in particular, the Square Kilometre Array, will offer a significant improvement to the Pulsar Timing Array sensitivity. In this article, we review the basic concepts of Pulsar Timing Array experiments, and discuss the latest results from the established Pulsar Timing Array collaborations.

scholarly journals Effects of periodicity in observation scheduling on parameter estimation of pulsar glitches

2021 ◽  
Author(s):  
L Dunn ◽  
M E Lower ◽  
A Melatos
Keyword(s):  
Radio Telescope ◽  
Additional Data ◽  
Hidden Markov ◽  
Phase Error ◽  
Synthetic Data ◽  
Time Of Arrival ◽  
Pulsar Timing ◽  
Public Data ◽  
Period Data ◽  
Timing Models

Abstract In certain pulsar timing experiments, where observations are scheduled approximately periodically (e.g. daily), timing models with significantly different frequencies (including but not limited to glitch models with different frequency increments) return near-equivalent timing residuals. The average scheduling aperiodicity divided by the phase error due to time-of-arrival uncertainties is a useful indicator of when the degeneracy is important. Synthetic data are used to explore the effect of this degeneracy systematically. It is found that phase-coherent tempo2 or temponest-based approaches are biased sometimes toward reporting small glitch sizes regardless of the true glitch size. Local estimates of the spin frequency alleviate this bias. A hidden Markov model is free from bias towards small glitches and announces explicitly the existence of multiple glitch solutions but sometimes fails to recover the correct glitch size. Two glitches in the UTMOST public data release are re-assessed, one in PSR J1709−4429 at MJD 58178 and the other in PSR J1452−6036 at MJD 58600. The estimated fractional frequency jump in PSR J1709−4429 is revised upward from Δf/f = (54.6 ± 1.0) × 10−9 to Δf/f = (2432.2 ± 0.1) × 10−9 with the aid of additional data from the Parkes radio telescope. We find that the available UTMOST data for PSR J1452−6036 are consistent with Δf/f = 270 × 10−9 + N/(fT) with N = 0, 1, 2, where T ≈ 1 siderealday is the observation scheduling period. Data from the Parkes radio telescope can be included, and the N = 0 case is selected unambiguously with a combined dataset.

scholarly journals Stochastic and continuous gravitational wave analysis pipelines for pulsar timing array data

2012 ◽  
Vol 8 (S291) ◽  
pp. 178-178
Author(s):  
Justin Ellis ◽  
Fredrick Jenet ◽  
Xavier Siemens ◽  
Maura McLaughlin
Keyword(s):  
Data Analysis ◽  
Gravitational Waves ◽  
Recent Progress ◽  
Simulated Data ◽  
Wave Analysis ◽  
Stochastic Background ◽  
Pulsar Timing ◽  
Timing Data ◽  
Timing Models ◽  
Pulsar Timing Array

AbstractThe Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration aims to detect gravitational waves (GWs) through the precise timing of millisecond pulsars. GWs will come in the form of a stochastic background, continuous sources and burst sources. Here we will review recent progress on the development of data analysis pipelines aimed at the detection of a stochastic background as well as continuous sources. We will introduce the Optimal Statistic and F-Statistic methods that are used in the stochastic and continuous pipelines, respectively. Both pipelines are fully functional on real pulsar timing data and take into account the timing models for each pulsar. Finally, we will present the efficacy of each pipeline on locally simulated data as well as data from the 2012 IPTA data challenge.

Unifying Bayesian Inference and Vector Space Models for Improved Decipherment

2015 ◽  
Author(s):  
Qing Dou ◽  
Ashish Vaswani ◽  
Kevin Knight ◽  
Chris Dyer
Keyword(s):  
Bayesian Inference ◽  
Vector Space ◽  
Vector Space Models

How do academics assess the results of multiple experiments?

2018 ◽  
Author(s):  
Olmo Van den Akker ◽  
Linda Dominguez Alvarez ◽  
Marjan Bakker ◽  
Jelte M. Wicherts ◽  
Marcel A. L. M. van Assen
Keyword(s):  
Bayesian Inference ◽  
Secondary Analysis ◽  
Individual Participant Data ◽  
Additional Experiment ◽  
Underlying Theory ◽  
Individual Participant ◽  
Vote Counting

We studied how academics assess the results of a set of four experiments that all test a given theory. We found that participants’ belief in the theory increases with the number of significant results, and that direct replications were considered to be more important than conceptual replications. We found no difference between authors and reviewers in their propensity to submit or recommend to publish sets of results, but we did find that authors are generally more likely to desire an additional experiment. In a preregistered secondary analysis of individual participant data, we examined the heuristics academics use to assess the results of four experiments. Only 6 out of 312 (1.9%) participants we analyzed used the normative method of Bayesian inference, whereas the majority of participants used vote counting approaches that tend to undervalue the evidence for the underlying theory if two or more results are statistically significant.

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