All Models Are Wrong: Noise Modelling in Pulsar Timing

Abstract:

Pulsar timing arrays are only as good as the timing residuals they produce — and those residuals are only as clean as the method used to extract them. Traditional template-matching approaches measure pulse time-of-arrival (TOA) by fitting a single fixed or radio-frequency dependent template to observed profiles, but this leaves a critical vulnerability: any stochastic variation in pulse shape is silently absorbed into the TOA as a systematic bias, quietly corrupting the signals we are trying to extract.

SCULPT is a new technique built of old ideas that fixes this at its source. By constructing a basis directly from observed profiles via SVD, SCULPT learns the true structure of pulse shape variability from the data itself — no analytic assumptions, no oracle knowledge required. Stochastic shape changes are absorbed into nuisance amplitude coefficients within this basis, keeping them out of the timing solution. The result is a variational profile basis that is optimally adapted to the actual pulse morphology: expressive where it needs to be, simple everywhere else.

I will present the methodology behind this process and explore with the audience what it is we’re trying to achieve and why it’s an important goal.

Please note that the event timezone is AEDT (UTC+11 hrs) and will be held in the Faraday room

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