Improving pulsar timing precision with single pulses

Abstract

The measurement error of pulse times of arrival (TOAs) in the high S/N limit is dominated by the quasi-random variation of a pulsar's emission profile from rotation to rotation. Like measurement noise, this noise is only reduced as the square root of observing time, posing a major challenge to future pulsar timing campaigns with large aperture telescopes, e.g. the Five-hundred-metre Aperture Spherical Telescope and the Square Kilometre Array.We propose a new method of pulsar timing that attempts to approximate the pulse-to-pulse variability with a small family of 'basis' pulses. If pulsar data are integrated over many rotations, this basis can be used to measure sub-pulse structure. Or, if high-time resolution data are available, the basis can be used to 'tag' single pulses and produce an optimal timing template. With realistic simulations, we show that these applications can dramatically reduce the effect of pulse-to-pulse variability on TOAs. Using high-time resolution data taken from the bright PSR J0835−4510 (Vela), we demonstrate a 25-40% improvement in TOA precision. Crucially for pulsar timing applications, we further establish that these techniques produce TOAs with gaussian residuals.Improvements of this level halve the telescope time required to reach a desired TOA precision. Although some gains can be achieved with existing data, the greatest improvements result from the 'tagging' approach, which in turn requires online or posthoc analysis of single pulses, an important consideration for the design of future instrumentation.

Periodic modulation in pulse arrival times from young pulsars: a renewed case for neutron star precession

“…However, searches for multiple sinusoids are computationally prohibitive, and we have visually examined the timing residuals for all 151 pulsars to search for any additional "obvious" modulation, finding none. As noted by Kerr (2015), the presence of strong timing noise causes sensitivity to coherent sinusoids to scale roughly as the square root of observing span. Thus, for most of our sample, substantial further observations will be required to detect modulations with lower amplitude.…”

Spin dynamics of a millisecond pulsar orbiting closely around a massive black hole

“…Besides gravitational wave, the spin-orbit coupling effect can be observed in pulsar timing observation. The correction to orbital precession would introduce extra shift of pulses received by a distant observer, and the spin precession and nutation could lead to the variation of pulse profiles, the detection of which has been shown to be possible (Kerr 2015). To estimate the effect of spin's precession and nutation, we adopt a toy model, using the light house model of pulsar here, as shown in Fig.…”

On a common carrier hypothesis for the 6613.6 and 6196.0 Å diffuse interstellar bands

“…For the purpose of this analysis, the shoulders, which are not perfectly resolved but seen reproducibly, are regarded as band-heads or subheads. We note that a very weak shoulder appears on the blue edge of the spectrum of Kerr et al (1996) and on two or three of the lines-of-sight in Galazutdinov et al (2002).…”

“…It has been demonstrated that the carrier of many of the DIBs are most probably free flying molecules (ions or radicals) (Ehrenfreund and Foing 1996;Sarre et al 1995;Kerr et al 1988; Motylewski et al 2000). Several attempts at spectroscopic analysis including rotational contour modeling have made plausible fits of the λ6614 DIB (Kerr et al 1996;Schulz et al 2000;Cami et al 2004;Oka et al 2013;Bernstein et al 2015;Marshall et al 2015) and the DIB near 5797Å (Edwards and Leach 1993;Rouan et al 1997;Huang and Oka 2015). Dahlstrom et al (2013) report that these two highly correlated DIBs show similar anomalous broadening in the spectrum of Herschel 36.…”