Analysis of Multi-hour Continuous Observations of Seven Millisecond Pulsars

Shapiro-Albert, Brent J.; McLaughlin, M. A.; Lam, Michael T.; Cordes, J. M.; Swiggum, Joseph K.

doi:10.3847/1538-4357/ab65f8

Cited by 7 publications

(2 citation statements)

References 78 publications

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“…Keith et al 2013), while changes in scattering time are often estimated using the statistical relation between the scintillation bandwidth (the frequency width of scintillation) and scattering time (e.g. Levin et al 2016;Shapiro-Albert et al 2020, see Verbiest & Shaifullah 2018 for a review of how these effects limit precision pulsar timing). Dispersion and scattering both scale strongly with frequency, and are often covariant.…”

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confidence: 99%

Measuring interstellar delays of PSR J0613−0200 over 7 yr, using the Large European Array for Pulsars

Main

Sanidas

Antoniadis

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Using data from the Large European Array for Pulsars (LEAP), and the Effelsberg telescope, we study the scintillation parameters of the millisecond pulsar PSR J0613−0200 over a 7 year timespan. The “secondary spectrum” – the 2D power spectrum of scintillation – presents the scattered power as a function of time delay, and contains the relative velocities of the pulsar, observer, and scattering material. We detect a persistent parabolic scintillation arc, suggesting scattering is dominated by a thin, anisotropic region. The scattering is poorly described by a simple exponential tail, with excess power at high delays; we measure significant, detectable scattered power at times out to ∼5μs, and measure the bulk scattering delay to be between 50 to 200 ns with particularly strong scattering throughout 2013. These delays are too small to detect a change of the pulse profile shape, yet they would change the times-of-arrival as measured through pulsar timing. The arc curvature varies annually, and is well fit by a one-dimensional scattering screen $\sim 40\%$ of the way towards the pulsar, with a changing orientation during the increased scattering in 2013. Effects of uncorrected scattering will introduce time delays correlated over time in individual pulsars, and may need to be considered in gravitational wave analyses. Pulsar timing programs would benefit from simultaneously recording in a way that scintillation can be resolved, in order to monitor the variable time delays caused by multipath propagation.

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confidence: 99%

Measuring interstellar delays of PSR J0613−0200 over 7 yr, using the Large European Array for Pulsars

Main

Sanidas

Antoniadis

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…INTRODUCTION Precision timing of millisecond pulsars (MSPs) has allowed us to study some of the most extreme astrophysical phenomena, from the equations of state of neutron stars (e.g., Antoniadis et al 2013;Stovall et al 2018;Cromartie et al 2020) to some of the most rigorous tests of general relativity (e.g., Kramer et al 2006;Archibald et al 2018;Zhu et al 2019). MSPs have also been used to study the properties and dynamics of the interstellar medium (ISM; e.g., Levin et al 2016;Jones et al 2017;Lam et al 2019;Shapiro-Albert et al 2020). Pulsar timing arrays (PTAs) made up of MSPs are used by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav;McLaughlin 2013), the European Pulsar Timing Array (EPTA; Kramer & Champion 2013), and the Parkes Pulsar Timing Array (PPTA; Hobbs 2013) to search for gravitational waves (GWs) from supermassive black hole binary systems (e.g., Shannon et al 2013;Zhu et al 2014;Lentati et al 2015;Shannon et al 2015;Arzoumanian et al 2016;Babak et al 2016;Verbiest et al 2016;Arzoumanian et al 2018b;Aggarwal et al 2019;Arzoumanian et al 2020a,b).…”

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confidence: 99%

A Study in Frequency-Dependent Effects on Precision Pulsar Timing Parameters with the Pulsar Signal Simulator

Shapiro-Albert,

Hazboun,

McLaughlin

et al. 2020

Preprint

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In this paper we introduce a new PYTHON package, the PULSAR SIGNAL SIMULATOR, or PSRSIGSIM, which is designed to simulate a pulsar signal from emission at the pulsar, through the interstellar medium, to observation by a radio telescope, and digitization in a standard data format. We use the PSRSIGSIM to simulate observations of three millisecond pulsars, PSRs J1744-1134, B1855+09, and B1953+29, to explore the covariances between frequency-dependent parameters, such as variations in the dispersion measure (DM), pulse profile evolution with frequency, and pulse scatter broadening. We show that the PSRSIGSIM can produce realistic simulated data and can accurately recover the parameters injected into the data. We also find that while there are covariances when fitting DM variations and frequency-dependent parameters, they have little effect on timing precision. Our simulations also show that time-variable scattering delays decrease the accuracy and increase the variability of the recovered DM and frequency-dependent parameters. Despite this, our simulations also show that the time-variable scattering delays have little impact on the root mean square of the timing residuals. This suggests that the variability seen in recovered DM, when time-variable scattering delays are present, is due to a covariance between the two parameters, with the DM modeling out the additional scattering delays.

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Electron Density Structure of the Local Galactic Disk

Ocker

Cordes²,

Chatterjee³

2020

ApJ

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Pulsar dispersion measures (DMs) have been used to model the electron density of the interstellar medium (ISM) in the Galactic disk as a plane-parallel medium, despite significant scatter in the DM-distance distribution and strong evidence for inhomogeneities in the ISM. We use a sample of pulsars with independent distance measurements to evaluate a model of the local ISM in the thick disk of the Galaxy that incorporates turbulent fluctuations, clumps, and voids in the electron density. The latter two components are required because about one-third of the lines of sight are discrepant from a strictly plane-parallel model. A likelihood analysis for smooth components of the model yields a scale height kpc and a mid-plane density n 0 = 0.015 ± 0.001 cm−3. The scatter in the DM-distance distribution is dominated by clumps and voids but receives significant contributions from a broad spectrum of density fluctuations, such as a Kolmogorov spectrum. The model is used to identify lines of sight with outlier values of DM. Three of these pulsars, J1614−2230, J1623−0908, and J1643−1224, lie behind known H ii regions, and the electron density model is combined with Hα intensity data to constrain the filling factors and other substructure properties of the H ii regions (Sh 2–7 and Sh 2–27). Several pulsars also exhibit enhanced DM fluctuations that are likely caused by an intersection of their lines of sight with the superbubble GSH 238+00+09.

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Analysis of Multi-hour Continuous Observations of Seven Millisecond Pulsars

Cited by 7 publications

References 78 publications

Measuring interstellar delays of PSR J0613−0200 over 7 yr, using the Large European Array for Pulsars

Measuring interstellar delays of PSR J0613−0200 over 7 yr, using the Large European Array for Pulsars

A Study in Frequency-Dependent Effects on Precision Pulsar Timing Parameters with the Pulsar Signal Simulator

Electron Density Structure of the Local Galactic Disk

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