Pulsar Timing: Experience from Fermi LAT

Pulsars are the most common Galactic GeV gamma-ray sources. Their spectra are hard, but cut off sharply in the energy range of the Large Area Telescope (LAT) on the Fermi satellite. Cherenkov telescopes have detected pulsations from 4 of the brightest of the nearly 300 LAT pulsars. CTAO’s improved sensitivity may triple the number of TeV pulsed detections, but will in any case detail the high energy spectral shape of those detected, to clarify the emission processes at play.

This seminar addresses the tools that CTAO needs in order to best exploit pulsed signals. The first is access to rotation ephemerides valid during the CTAO data epochs. These can be made from Fermi-LAT data. Some radio timing may also be needed. Other tools include procedures to test CTAO’s event timestamp accuracy, and reliable software to convert the gamma-ray arrival times to neutron star rotational phases. Prof. Smith will talk about how they solved these problems for the Fermi-LAT, and compare with CTAO. The above may sound dry, but he will favor anecdotes of “lessons learned,” and leave the arcane details for offline study.