scholarly journals The UTMOST pulsar timing programme – II. Timing noise across the pulsar population

2020 ◽  
Vol 494 (1) ◽  
pp. 228-245 ◽  
Author(s):  
M E Lower ◽  
M Bailes ◽  
R M Shannon ◽  
S Johnston ◽  
C Flynn ◽  
...  
Keyword(s):  
Large Scale ◽  
Rotational Stability ◽  
Scaling Relation ◽  
Noise Strength ◽  
Radio Pulsars ◽  
Bayesian Techniques ◽  
Pulsar Timing ◽  
Rotational Evolution ◽  
Timing Noise ◽  
Noise Models

ABSTRACT While pulsars possess exceptional rotational stability, large-scale timing studies have revealed at least two distinct types of irregularities in their rotation: red timing noise and glitches. Using modern Bayesian techniques, we investigated the timing noise properties of 300 bright southern-sky radio pulsars that have been observed over 1.0–4.8 yr by the upgraded Molonglo Observatory Synthesis Telescope (MOST). We reanalysed the spin and spin-down changes associated with nine previously reported pulsar glitches, report the discovery of three new glitches and four unusual glitch-like events in the rotational evolution of PSR J1825−0935. We develop a refined Bayesian framework for determining how red noise strength scales with pulsar spin frequency (ν) and spin-down frequency ($\dot{\nu }$), which we apply to a sample of 280 non-recycled pulsars. With this new method and a simple power-law scaling relation, we show that red noise strength scales across the non-recycled pulsar population as $\nu ^{a} |\dot{\nu }|^{b}$, where $a = -0.84^{+0.47}_{-0.49}$ and $b = 0.97^{+0.16}_{-0.19}$. This method can be easily adapted to utilize more complex, astrophysically motivated red noise models. Lastly, we highlight our timing of the double neutron star PSR J0737−3039, and the rediscovery of a bright radio pulsar originally found during the first Molonglo pulsar surveys with an incorrectly catalogued position.

scholarly journals Diagnostics of interstellar medium parameters on non-discrete timing irregularities of pulsars

2021 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
E. U. Iyida ◽  
C. I. Eze
Keyword(s):  
Interstellar Medium ◽  
Stability Parameter ◽  
Rotational Stability ◽  
Radio Pulsars ◽  
Activity Parameter ◽  
Significant Relationships ◽  
Pulsar Timing ◽  
Rotation Measure ◽  
Over 40 Years ◽  
Statistical Effects

In this paper, a large homogenous sample of Jodrell Bank Observatory (JBO) radio pulsars was used to investigate the statistical effects of interstellar medium (ISM) parameters: dispersion and rotation measure (DM and RM, respectively) on non-discrete timing irregularities of our sample (whose observed timing activity timescales span over 40 years). This is done by using the correlations between the measured DM and RM, and some parameters that have been commonly used to measure non-discrete timing irregularities [timing activity parameter (A), the amount of timing fluctuations absorbed by the cubic term (σR23), measure of pulsar rotational stability (σz ) and stability parameter (∆8)]. Our results show that ISM parameters positively correlate (r > 0.60) with the pulsar timing irregularities parameters of our sample. The significant relationships observed are discussed.  

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 A pulsar-based time-scale from the International Pulsar Timing Array

2019 ◽  
Vol 491 (4) ◽  
pp. 5951-5965 ◽  
Author(s):  
G Hobbs ◽  
L Guo ◽  
R N Caballero ◽  
W Coles ◽  
K J Lee ◽  
...  
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Limiting Factor ◽  
Radio Pulsars ◽  
Pulsar Timing ◽  
The Us ◽  
The Stability ◽  
Solar System Dynamics ◽  
Noise Models ◽  
Pulsar Timing Array

ABSTRACT We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar time-scale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected time-scale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based time-scales are unlikely to contribute to the stability of the best time-scales over the next decade, but they will remain a valuable independent check on atomic time-scales. We also find that the stability of the pulsar-based time-scale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves.

scholarly journals Probing fundamental physics with pulsars

2009 ◽  
Vol 5 (H15) ◽  
pp. 131-136
Author(s):  
Duncan R. Lorimer ◽  
Maura A. McLaughlin
Keyword(s):  
Large Scale ◽  
Radio Pulsars ◽  
Fundamental Physics ◽  
Superdense Matter ◽  
Pulsar Timing ◽  
Binary Evolution ◽  
Radio Transients ◽  
Pulsar Timing Array ◽  
Review Current ◽  
Pulsar Evolution

AbstractPulsars provide a wealth of information about General Relativity, the equation of state of superdense matter, relativistic particle acceleration in high magnetic fields, the Galaxy's interstellar medium and magnetic field, stellar and binary evolution, celestial mechanics, planetary physics and even cosmology. The wide variety of physical applications currently being investigated through studies of radio pulsars rely on: (i) finding interesting objects to study via large-scale and targeted surveys; (ii) high-precision timing measurements which exploit their remarkable clock-like stability. We review current surveys and the principles of pulsar timing and highlight progress made in the rotating radio transients, intermittent pulsars, tests of relativity, understanding pulsar evolution, measuring neutron star masses and the pulsar timing array

scholarly journals Timing of young radio pulsars – II. Braking indices and their interpretation

2020 ◽  
Vol 494 (2) ◽  
pp. 2012-2026 ◽  
Author(s):  
A Parthasarathy ◽  
S Johnston ◽  
R M Shannon ◽  
L Lentati ◽  
M Bailes ◽  
...  
Keyword(s):  
Time Scales ◽  
Radio Telescope ◽  
Archival Data ◽  
Radio Pulsars ◽  
Pulsar Timing ◽  
Timing Noise

ABSTRACT In Paper I of this series, we detected a significant value of the braking index (n) for 19 young, high-$\dot{E}$ radio pulsars using ∼10 yr of timing observations from the 64-m Parkes radio telescope. Here, we investigate this result in more detail using a Bayesian pulsar timing framework to model timing noise and to perform selection to distinguish between models containing exponential glitch recovery and braking index signatures. We show that consistent values of n are maintained with the addition of substantial archival data, even in the presence of glitches. We provide strong arguments that our measurements are unlikely due to exponential recovery signals from unseen glitches even though glitches play a key role in the evolution of a pulsar’s spin frequency. We conclude that, at least over decadal time-scales, the value of n can be significantly larger than the canonical 3 and discuss the implications for the evolution of pulsars.

scholarly journals Modeling pulsar time noise with long term decay modulated by short term oscillations of the magnetic fields of neutron stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 561-561
Author(s):  
Yi Xie ◽  
Shuangnan Zhang
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
Radio Pulsars ◽  
Short Term ◽  
Pulsar Time ◽  
Power Law Decay ◽  
Pulsar Timing ◽  
Model Predictions ◽  
Timing Noise

AbstractWe model the evolution of the magnetic fields of neutron stars as consisting of a long term power-law decay modulated by short term small amplitude oscillations. Our model predictions on the timing noise of neutron stars agree well with the observed statistical properties and correlations of normal radio pulsars. For individual pulsars our model can effectively reduce their timing residuals, thus offering the potential of more sensitive detections of gravitational waves with pulsar timing arrays. Finally our model can also re-produce their observed correlation and oscillations of second derivative of frenquency, as well as the “slow glitch” phenomenon.

scholarly journals Diagnostics of timing noise in middle-aged pulsars

2019 ◽  
Vol 487 (4) ◽  
pp. 5854-5861 ◽  
Author(s):  
Nakornping Namkham ◽  
Phrudth Jaroenjittichai ◽  
Simon Johnston
Keyword(s):  
Gravitational Wave ◽  
Radio Telescope ◽  
Strong Correlation ◽  
Radio Pulsars ◽  
Middle Aged ◽  
Monthly Basis ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
Timing Noise

ABSTRACT Radio pulsars are often used as clocks in a wide variety of experiments. Imperfections in the clock, known as timing noise, have the potential to reduce the significance of, or even thwart e.g. the attempt to find a stochastic gravitational wave (GW) background. We measure the timing noise in a group of 129 mostly middle-aged pulsars (i.e. characteristic ages near 1 Myr) observed with the Parkes radio telescope on a monthly basis since 2014. We examine four different metrics for timing noise, but it remains unclear which, if any, provides the best determination. In spite of this, it is evident that these pulsars have significantly less timing noise than their younger counterparts, but significantly more than the (much older) millisecond pulsars (MSPs). As with previous authors, we find a strong correlation between timing noise and the pulsar spin-down rate, $\dot{\nu}$. However, for a given $\dot{\nu}$ there is a spread of about a factor of 30 in the strength of the timing noise likely indicating that nuclear conditions in the interior of the stars differ between objects. We briefly comment on the implications for GW detection through pulsar timing arrays as the level of timing noise in MSPs may be less than predicted.

scholarly journals Rotational Instabilities in Pulsars

1996 ◽  
Vol 160 ◽  
pp. 73-81 ◽  
Author(s):  
A. G. Lyne
Keyword(s):  
Angular Momentum ◽  
Neutron Star ◽  
Internal Structure ◽  
Rotational Stability ◽  
Radio Pulsars ◽  
Millisecond Pulsars ◽  
General Radio ◽  
Observational Status ◽  
Timing Noise ◽  
Star Structure

AbstractIn general, radio pulsars are superb clocks. However a few years after their discovery, it became clear that some pulsars show significant departures from their regular slow-down which make their rotation unpredictable. Two main forms of irregularities have been identified – glitches and timing noise – which are most marked in, but not confined to, young pulsars. Both are probably related to the internal structure of the neutron star and the properties of the internal neutron superfluid which prevent the smooth outward flow of angular momentum as the star slows down. In this review, the observational status and statistical aspects of the phenomena are described. We do not discuss in any detail their implications for neutron star structure. Rather, we consider them in so far as they limit studies in which the rotational stability is paramount and may limit the use of pulsars as astronomical chronometers. Glitch activity, the amount of post-glitch relaxation and the amplitude of timing noise all depend roughly linearly on the frequency derivative, implying that even the millisecond pulsars are prone to these effects.

scholarly journals Precision Pulsar Timing with NASA's Deep Space Network

2015 ◽  
Vol 11 (A29B) ◽  
pp. 367-369
Author(s):  
Lawrence Teitelbaum ◽  
Walid Majid ◽  
Manuel M. Franco ◽  
Daniel J. Hoppe ◽  
Shinji Horiuchi ◽  
...  
Keyword(s):  
Low Frequency ◽  
Radio Waves ◽  
Deep Space ◽  
Radio Pulsars ◽  
Deep Space Network ◽  
Space Network ◽  
The Earth ◽  
Pulsar Timing ◽  
Initial Results ◽  
Stable Rotation

AbstractMillisecond pulsars (MSPs) are a class of radio pulsars with extremely stable rotation. Their excellent timing stability can be used to study a wide variety of astrophysical phenomena. In particular, a large sample of these pulsars can be used to detect low-frequency gravitational waves. We have developed a precision pulsar timing backend for the NASA Deep Space Network (DSN), which will allow the use of short gaps in tracking schedules to time pulses from an ensemble of MSPs. The DSN operates clusters of large dish antennas (up to 70-m in diameter), located roughly equidistant around the Earth, for communication and tracking of deep-space spacecraft. The backend system will be capable of removing entirely the dispersive effects of propagation of radio waves through the interstellar medium in real-time. We will describe our development work, initial results, and prospects for future observations over the next few years.

scholarly journals A comparison of Galactic electron density models using PyGEDM

2021 ◽  
Vol 38 ◽  
Author(s):  
D. C. Price ◽  
C. Flynn ◽  
A. Deller
Keyword(s):  
Electron Density ◽  
Large Scale ◽  
Galactic Halo ◽  
Application Programming Interface ◽  
Dispersion Measure ◽  
Radio Pulsars ◽  
Distribution Models ◽  
Distance Measurements ◽  
Application Programming ◽  
The Impact

Abstract Galactic electron density distribution models are crucial tools for estimating the impact of the ionised interstellar medium on the impulsive signals from radio pulsars and fast radio bursts. The two prevailing Galactic electron density models (GEDMs) are YMW16 (Yao et al. 2017, ApJ, 835, 29) and NE2001 (Cordes & Lazio 2002, arXiv e-prints, pp astro–ph/0207156). Here, we introduce a software package PyGEDM which provides a unified application programming interface for these models and the YT20 (Yamasaki & Totani 2020, ApJ, 888, 105) model of the Galactic halo. We use PyGEDM to compute all-sky maps of Galactic dispersion measure (DM) for YMW16 and NE2001 and compare the large-scale differences between the two. In general, YMW16 predicts higher DM values towards the Galactic anticentre. YMW16 predicts higher DMs at low Galactic latitudes, but NE2001 predicts higher DMs in most other directions. We identify lines of sight for which the models are most discrepant, using pulsars with independent distance measurements. YMW16 performs better on average than NE2001, but both models show significant outliers. We suggest that future campaigns to determine pulsar distances should focus on targets where the models show large discrepancies, so future models can use those measurements to better estimate distances along those line of sight. We also suggest that the Galactic halo should be considered as a component in future GEDMs, to avoid overestimating the Galactic DM contribution for extragalactic sources such as FRBs.

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