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Proper Motion Measurements of Radio-Quiet Pulsars Using -ray Single Photons

Presentation #107.29 in the session Stellar/Compact Objects - Poster Session.

Published onMay 03, 2024
Proper Motion Measurements of Radio-Quiet Pulsars Using -ray Single Photons

Measuring the proper motion of young pulsars informs us about the birth mechanisms and locations of neutron stars, and measuring proper motions is possible through radio- and -ray pulsar timing. -ray pulsar timing is generally more difficult due to the low number of collected -ray photons and confusion with background sources. For comparison, creating a good signal-to-noise ratio radio pulse time-of-arrival (TOA) requires averaging over 102 to 103 pulses (slow pulsars) or 104 to 106 pulses (millisecond pulsars), which can be typically done within an hour of radio observations. However, a similar analysis in -rays would require averaging over weeks to months of data for most pulsars due to an extremely low photon count rate. Given this low count rate, it is advantageous to extract the maximum amount of information from each photon. We do this by using Bayesian analysis and MCMC techniques with PINT to time -ray pulsars using single photons. This technique allows us to take advantage of the long, 14-yr Fermi-LAT data set. For several of our pulsars, we have found significant red noise, correlated noise that has higher power in the lower frequencies, which causes the pulse to wander. To fully account for the noise within our data, we have had to incorporate a more complex noise analysis that uses a sum of sinusoidal waves alongside our Bayesian MCMC analysis. I will present our selection criteria, the techniques we used to measure the proper motions of young radio-quiet -ray pulsars and our results.

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