Frequency-Dependent Template Profiles for High Precision Pulsar Timing. (arXiv:1812.02006v1 [astro-ph.HE])

Frequency-Dependent Template Profiles for High Precision Pulsar Timing. (arXiv:1812.02006v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pennucci_T/0/1/0/all/0/1">Timothy T. Pennucci</a>

Pulsar timing experiments require high fidelity template profiles in order to
minimize the biases in pulse time-of-arrival (TOA) measurements and their
uncertainties. Efforts to acquire more precise TOAs given fixed effective area
of telescopes, finite receiver noise, and limited integration time have led
pulsar astronomers to the solution of implementing ultra-wideband receivers.
This solution, however, has run up against the problem that pulse profile
shapes evolve with frequency, which raises the question of how to properly
measure and analyze TOAs obtained using template-matching methods. This paper
proposes a new method for one facet of this problem, that of template profile
generation, and demonstrates it on the well-timed millisecond pulsar
J1713+0747. Specifically, we decompose pulse profile evolution into a linear
combination of basis eigenvectors, the coefficients of which change slowly with
frequency such that their evolution is modeled simply by a sum of low degree
piecewise polynomial spline functions. These noise-free, high fidelity,
frequency-dependent templates can be used to make measurements of so-called
“wideband TOAs” simultaneously with an estimate of the instantaneous dispersion
measure. The use of wideband TOAs is becoming important for pulsar timing array
experiments, as the volume of datasets comprised of conventional, subbanded
TOAs are quickly becoming unwieldly for the Bayesian analyses needed to uncover
latent gravitational wave signals. Although motivated by high precision timing
experiments, our technique is applicable in more general pulsar observations.

Pulsar timing experiments require high fidelity template profiles in order to
minimize the biases in pulse time-of-arrival (TOA) measurements and their
uncertainties. Efforts to acquire more precise TOAs given fixed effective area
of telescopes, finite receiver noise, and limited integration time have led
pulsar astronomers to the solution of implementing ultra-wideband receivers.
This solution, however, has run up against the problem that pulse profile
shapes evolve with frequency, which raises the question of how to properly
measure and analyze TOAs obtained using template-matching methods. This paper
proposes a new method for one facet of this problem, that of template profile
generation, and demonstrates it on the well-timed millisecond pulsar
J1713+0747. Specifically, we decompose pulse profile evolution into a linear
combination of basis eigenvectors, the coefficients of which change slowly with
frequency such that their evolution is modeled simply by a sum of low degree
piecewise polynomial spline functions. These noise-free, high fidelity,
frequency-dependent templates can be used to make measurements of so-called
“wideband TOAs” simultaneously with an estimate of the instantaneous dispersion
measure. The use of wideband TOAs is becoming important for pulsar timing array
experiments, as the volume of datasets comprised of conventional, subbanded
TOAs are quickly becoming unwieldly for the Bayesian analyses needed to uncover
latent gravitational wave signals. Although motivated by high precision timing
experiments, our technique is applicable in more general pulsar observations.

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