A Study in Frequency-Dependent Effects on Precision Pulsar Timing Parameters with the Pulsar Signal Simulator. (arXiv:2010.07301v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Shapiro_Albert_B/0/1/0/all/0/1">Brent J. Shapiro-Albert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hazboun_J/0/1/0/all/0/1">Jeffrey S. Hazboun</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McLaughlin_M/0/1/0/all/0/1">Maura A. McLaughlin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lam_M/0/1/0/all/0/1">Michael T. Lam</a>
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$-$1134, B1855+09, and B1953+29, to explore the covariances between
frequency-dependent parameters, such as variations in the dispersion measure
(DM), pulse profile evolution with frequency, and pulse scatter broadening. We
show that the PsrSigSim can produce realistic simulated data and can accurately
recover the parameters injected into the data. We also find that while there
are covariances when fitting DM variations and frequency-dependent parameters,
they have little effect on timing precision. Our simulations also show that
time-variable scattering delays decrease the accuracy and increase the
variability of the recovered DM and frequency-dependent parameters. Despite
this, our simulations also show that the time-variable scattering delays have
little impact on the root mean square of the timing residuals. This suggests
that the variability seen in recovered DM, when time-variable scattering delays
are present, is due to a covariance between the two parameters, with the DM
modeling out the additional scattering delays.
In this paper we introduce a new Python package, the {Pulsar Signal
Simulator, or PsrSigSim, which is designed to simulate a pulsar signal from
emission at the pulsar, through the interstellar medium, to observation by a
radio telescope, and digitization in a standard data format. We use the
PsrSigSim to simulate observations of three millisecond pulsars, PSRs
J1744$-$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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