scholarly journals Tracking dispersion measure variations of timing array pulsars with the GMRT

2012 ◽  
Vol 8 (S291) ◽  
pp. 432-434 ◽  
Author(s):  
Ujjwal Kumar ◽  
Yashwant Gupta ◽  
Willem van Straten ◽  
Stefan Osłowski ◽  
Jayanta Roy ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Corona ◽  
Radio Telescope ◽  
Line Of Sight ◽  
Dispersion Measure ◽  
Millisecond Pulsars ◽  
Preliminary Comparison ◽  
Pulsar Timing ◽  
Single Epoch ◽  
Pulsar Timing Array

AbstractWe present the results from nearly three years of monitoring of the variations in dispersion measure (DM) along the line-of-sight to 11 millisecond pulsars using the Giant Metrewave Radio Telescope (GMRT). These results demonstrate accuracies of single epoch DM estimates of the order of 5 × 10−4 cm−3 pc. A preliminary comparison with the Parkes Pulsar Timing Array (PPTA) data shows that the measured DM fluctuations are comparable. We show effects of DM variations due to the solar wind and solar corona and compare with the existing models.

scholarly journals Rotation Measure variations for millisecond pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 568-570
Author(s):  
Wenming Yan ◽  
R. N. Manchester ◽  
Na Wang
Keyword(s):  
Radio Telescope ◽  
Position Angle ◽  
Polarization Mode ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
Rotation Measure ◽  
The Mean ◽  
Pulsar Timing Array

AbstractAs part of the Parkes Pulsar Timing Array (PPTA) project, frequent observations of 20 millisecond pulsars are made using the Parkes 64-m radio telescope. Variations in the mean position angle of the 20 millisecond pulsars can be studied by the PPTA data being recorded in full-polarization mode. We briefly discuss these results.

scholarly journals Commensal discovery of four fast radio bursts during Parkes Pulsar Timing Array observations

2019 ◽  
Vol 488 (1) ◽  
pp. 868-875 ◽  
Author(s):  
S Osłowski ◽  
R M Shannon ◽  
V Ravi ◽  
J F Kaczmarek ◽  
S Zhang ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Spectral Properties ◽  
Signal To Noise Ratio ◽  
Radio Bursts ◽  
Signal To Noise ◽  
Fundamental Physics ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
Physics Experiments ◽  
Pulsar Timing Array

ABSTRACT The Parkes Pulsar Timing Array (PPTA) project monitors two dozen millisecond pulsars (MSPs) in order to undertake a variety of fundamental physics experiments using the Parkes 64-m radio telescope. Since 2017 June, we have been undertaking commensal searches for fast radio bursts (FRBs) during the MSP observations. Here, we report the discovery of four FRBs (171209, 180309, 180311, and 180714). The detected events include an FRB with the highest signal-to-noise ratio ever detected at the Parkes Observatory, which exhibits unusual spectral properties. All four FRBs are highly polarized. We discuss the future of commensal searches for FRBs at Parkes.

scholarly journals Pulsar science with the CHIME telescope

2017 ◽  
Vol 13 (S337) ◽  
pp. 179-182 ◽  
Author(s):  
Cherry Ng
Keyword(s):  
Northern Hemisphere ◽  
Radio Telescope ◽  
Field Of View ◽  
Radio Bursts ◽  
Radio Telescopes ◽  
Acoustic Oscillations ◽  
Daily Monitoring ◽  
Intensity Mapping ◽  
Pulsar Timing ◽  
Pulsar Timing Array

AbstractThe CHIME telescope (the Canadian Hydrogen Intensity Mapping Experiment) recently built in Penticton, Canada, is currently being commissioned. Originally designed as a cosmology experiment, it was soon recognized that CHIME has the potential to simultaneously serve as an incredibly useful radio telescope for pulsar science. CHIME operates across a wide bandwidth of 400–800 MHz and will have a collecting area and sensitivity comparable to that of the 100-m class radio telescopes. CHIME has a huge field of view of ~250 square degrees. It will be capable of observing 10 pulsars simultaneously, 24-hours per day, every day, while still accomplishing its missions to study Baryon Acoustic Oscillations and Fast Radio Bursts. It will carry out daily monitoring of roughly half of all pulsars in the northern hemisphere, including all NANOGrav pulsars employed in the Pulsar Timing Array project. It will cycle through all pulsars in the northern hemisphere with a range of cadence of no more than 10 days.

scholarly journals Identifying and mitigating noise sources in precision pulsar timing data sets

2020 ◽  
Author(s):  
Boris Goncharov ◽  
D J Reardon ◽  
R M Shannon ◽  
Xing-Jiang Zhu ◽  
Eric Thrane ◽  
...  
Keyword(s):  
Gravitational Waves ◽  
Physical Models ◽  
Dispersion Measure ◽  
Data Sets ◽  
Pulse Profile ◽  
Noise Sources ◽  
Arrival Times ◽  
Pulsar Timing ◽  
Noise Models ◽  
Pulsar Timing Array

Abstract Pulsar timing array projects measure the pulse arrival times of millisecond pulsars for the primary purpose of detecting nanohertz-frequency gravitational waves. The measurements include contributions from a number of astrophysical and instrumental processes, which can either be deterministic or stochastic. It is necessary to develop robust statistical and physical models for these noise processes because incorrect models diminish sensitivity and may cause a spurious gravitational wave detection. Here we characterise noise processes for the 26 pulsars in the second data release of the Parkes Pulsar Timing Array using Bayesian inference. In addition to well-studied noise sources found previously in pulsar timing array data sets such as achromatic timing noise and dispersion measure variations, we identify new noise sources including time-correlated chromatic noise that we attribute to variations in pulse scattering. We also identify “exponential dip” events in four pulsars, which we attribute to magnetospheric effects as evidenced by pulse profile shape changes observed for three of the pulsars. This includes an event in PSR J1713+0747, which had previously been attributed to interstellar propagation. We present noise models to be used in searches for gravitational waves. We outline a robust methodology to evaluate the performance of noise models and identify unknown signals in the data. The detection of variations in pulse profiles highlights the need to develop efficient profile domain timing methods.

scholarly journals High-precision timing of 42 millisecond pulsars with the European Pulsar Timing Array

2016 ◽  
Vol 458 (3) ◽  
pp. 3341-3380 ◽  
Author(s):  
G. Desvignes ◽  
R. N. Caballero ◽  
L. Lentati ◽  
J. P. W. Verbiest ◽  
D. J. Champion ◽  
...  
Keyword(s):  
High Precision ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
Pulsar Timing Array

scholarly journals Gravitational wave research using pulsar timing arrays

2017 ◽  
Vol 4 (5) ◽  
pp. 707-717 ◽  
Author(s):  
George Hobbs ◽  
Shi Dai
Keyword(s):  
Gravitational Wave ◽  
High Precision ◽  
Low Frequency ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
Distributed Array ◽  
The Status ◽  
Wave Research ◽  
Near Future ◽  
Pulsar Timing Array

Abstract A pulsar timing array (PTA) refers to a program of regular, high-precision timing observations of a widely distributed array of millisecond pulsars. Here we review the status of the three primary PTA projects and the joint International Pulsar Timing Array project. We discuss current results related to ultra-low-frequency gravitational wave searches and highlight opportunities for the near future.

scholarly journals Correlated timing noise and high-precision pulsar timing: measuring frequency second derivatives as an example

2019 ◽  
Vol 488 (2) ◽  
pp. 2190-2201 ◽  
Author(s):  
X J Liu ◽  
M J Keith ◽  
C G Bassa ◽  
B W Stappers
Keyword(s):  
Measurement Uncertainty ◽  
High Precision ◽  
Power Law ◽  
Power Laws ◽  
Noise Model ◽  
Dispersion Measure ◽  
Pulsar Timing ◽  
Timing Noise ◽  
The Impact ◽  
Pulsar Timing Array

Abstract We investigate the impact of noise processes on high-precision pulsar timing. Our analysis focuses on the measurability of the second spin frequency derivative $\ddot{\nu }$. This $\ddot{\nu }$ can be induced by several factors including the radial velocity of a pulsar. We use Bayesian methods to model the pulsar times-of-arrival in the presence of red timing noise and dispersion measure variations, modelling the noise processes as power laws. Using simulated times-of-arrival that both include red noise, dispersion measure variations, and non-zero $\ddot{\nu }$ values, we find that we are able to recover the injected $\ddot{\nu }$, even when the noise model used to inject and recover the input parameters are different. Using simulations, we show that the measurement uncertainty on $\ddot{\nu }$ decreases with the timing baseline T as Tγ, where γ = −7/2 + α/2 for power-law noise models with shallow power-law indices α (0 < α < 4). For steep power-law indices (α > 8), the measurement uncertainty reduces with T−1/2. We applied this method to times-of-arrival from the European Pulsar Timing Array and the Parkes Pulsar Timing Array and determined $\ddot{\nu }$ probability density functions for 49  millisecond pulsars. We find a statistically significant $\ddot{\nu }$ value for PSR B1937+21 and consider possible options for its origin. Significant (95 per cent C.L.) values for $\ddot{\nu }$ are also measured for PSRs J0621+1002 and J1022+1001, thus future studies should consider including it in their ephemerides. For binary pulsars with small orbital eccentricities, such as PSR J1909−3744, extended ELL1 models should be used to overcome computational issues. The impacts of our results on the detection of gravitational waves are also discussed.

scholarly journals Dispersion measure variability for 36 millisecond pulsars at 150 MHz with LOFAR

2020 ◽  
Vol 644 ◽  
pp. A153
Author(s):  
J. Y. Donner ◽  
J. P. W. Verbiest ◽  
C. Tiburzi ◽  
S. Osłowski ◽  
J. Künsemöller ◽  
...  
Keyword(s):  
Time Series ◽  
Low Frequency ◽  
Propagation Delay ◽  
Dispersion Measure ◽  
Millisecond Pulsars ◽  
Low Frequencies ◽  
Pulsar Timing ◽  
Variable Dispersion ◽  
Delay Variations ◽  
Plasma Dispersion

Context. Radio pulses from pulsars are affected by plasma dispersion, which results in a frequency-dependent propagation delay. Variations in the magnitude of this effect lead to an additional source of red noise in pulsar timing experiments, including pulsar timing arrays (PTAs) that aim to detect nanohertz gravitational waves. Aims. We aim to quantify the time-variable dispersion with much improved precision and characterise the spectrum of these variations. Methods. We use the pulsar timing technique to obtain highly precise dispersion measure (DM) time series. Our dataset consists of observations of 36 millisecond pulsars, which were observed for up to 7.1 yr with the LOw Frequency ARray (LOFAR) telescope at a centre frequency of ~150 MHz. Seventeen of these sources were observed with a weekly cadence, while the rest were observed at monthly cadence. Results. We achieve a median DM precision of the order of 10−5 cm−3 pc for a significant fraction of our sources. We detect significant variations of the DM in all pulsars with a median DM uncertainty of less than 2 × 10−4 cm−3 pc. The noise contribution to pulsar timing experiments at higher frequencies is calculated to be at a level of 0.1–10 μs at 1.4 GHz over a timespan of a few years, which is in many cases larger than the typical timing precision of 1 μs or better that PTAs aim for. We found no evidence for a dependence of DM on radio frequency for any of the sources in our sample. Conclusions. The DM time series we obtained using LOFAR could in principle be used to correct higher-frequency data for the variations of the dispersive delay. However, there is currently the practical restriction that pulsars tend to provide either highly precise times of arrival (ToAs) at 1.4 GHz or a high DM precision at low frequencies, but not both, due to spectral properties. Combining the higher-frequency ToAs with those from LOFAR to measure the infinite-frequency ToA and DM would improve the result.

scholarly journals Pulsar science with data from the Large European Array for Pulsars

2017 ◽  
Vol 13 (S337) ◽  
pp. 374-375
Author(s):  
James W. McKee
Keyword(s):  
Galactic Centre ◽  
Radio Telescopes ◽  
Central Frequency ◽  
Millisecond Pulsars ◽  
Pulsar Timing ◽  
The Individual ◽  
Pulsar Timing Array

AbstractThe Large European Array for Pulsars (LEAP) is a European Pulsar Timing Array project that combines the Lovell, Effelsberg, Nançay, Sardinia, and Westerbork radio telescopes into a single tied-array, and makes monthly observations of a set of millisecond pulsars (MSPs). The overview of our experiment is presented in Bassa et al. (2016). Baseband data are recorded at a central frequency of 1396 MHz and a bandwidth of 128 MHz at each telescope, and are correlated offline on a cluster at Jodrell Bank Observatory using a purpose-built correlator, detailed in Smits et al. (2017). LEAP offers a substantial increase in sensitivity over that of the individual telescopes, and can operate in timing and imaging modes (notably in observations of the galactic centre radio magnetar; Wucknitz 2015). To date, 4 years of observations have been reduced. Here, we report on the scientific projects which have made use of LEAP data.

scholarly journals Pulsar science at the Sardinia Radio Telescope

2017 ◽  
Vol 13 (S337) ◽  
pp. 392-393
Author(s):  
D. Perrodin ◽  
M. Burgay ◽  
A. Corongiu ◽  
M. Pilia ◽  
A. Possenti ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Radio Telescope ◽  
Galactic Center ◽  
Active Surface ◽  
Radio Bursts ◽  
Extraterrestrial Intelligence ◽  
Wave Detection ◽  
Pulsar Timing ◽  
Wide Range ◽  
Pulsar Timing Array

AbstractThe Sardinia Radio Telescope (SRT) is a modern, fully-steerable 64-m dish located in San Basilio, Sardinia (Italy). It is characterized by an active surface that allows it to cover a wide range of radio frequencies (300 MHz to 100 GHz). During SRT’s commissioning phase, we installed the hardware and software needed for pulsar observations. Since then, SRT has taken part in Large European Array for Pulsars and European Pulsar Timing Array observations for the purpose of gravitational wave detection. We have installed a new S-band receiver that will allow us to search for pulsars in the Galactic Center. We also plan to combine our efforts to search for Extraterrestrial Intelligence (SETI) with the search for pulsars and Fast Radio Bursts.

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