Millisecond Pulsars in a New Light: Insights from High-Speed Optical Photometry

by Dr Alessandro Papitto (INAF-OAR)

Thursday 11 Dec 2025, 11:30 → 12:30 Europe/Rome

Sala Jappelli (Osservatorio astronomico di Padova)

Spinning hundreds of times per second, millisecond pulsars are extraordinary laboratories for testing theories of gravity, detecting gravitational waves, and probing matter under extreme densities. Traditionally, they have been observed in two distinct states: as rotation-powered radio/gamma-ray pulsars, or as X-ray pulsars energised by accretion from a companion star. The discovery of transitional pulsars, switching between these regimes as the accretion rate varies, has blurred this long-standing dichotomy.

Ultra-fast optical photometers such as SiFAP2 and Aqueye+ have now added a key dimension to these studies. Their detection of remarkably bright optical pulsations from two millisecond pulsars suggests that magnetospheric particle acceleration can persist even in the presence of an accretion disk, challenging conventional models. The identification of optical pulses from a strictly rotation-powered millisecond pulsar further highlights the broader potential of fast optical photometry. I will review these pioneering observations, discuss their implications for pulsar emission models, and outline future opportunities, including applications to luminous low-mass X-ray binaries.

 

Join Zoom Meeting

 

https://unipd.zoom.us/j/82482883288?pwd=MVvmMWSGaiVrGMyAFOdyQG61OAcI7D.1

Meeting ID: 824 8288 3288

Passcode: 072472