Seminars

BIO: Dr Alessandro Papitto is a Primo Ricercatore (Research Scientist) in the High-Energy Astrophysics group at the INAF Osservatorio Astronomico di Roma, where he leads a team focused on millisecond pulsars. He previously held a Marie Skłodowska-Curie individual fellowship in Rome and a Juan de la Cierva fellowship at the Institute of Space Sciences in Barcelona. With extensive experience in timing studies across X-ray, radio, and gamma-ray energies, the discovery of the prototype of a transitional millisecond pulsar is one of his main achievements. He is currently the scientific coordinator for the SiFAP2 fast photometer project, which obtained the pioneering detection of optical pulsations from millisecond pulsars.

COLLOQUIUM

Alessandro PAPITTO

INAF - OAR

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

11 Dec 2025, 11:30, Aula Jappelli

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.

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IMP: Thursday afternoon, the speaker will meet with students and post-docs at 4:30 PM in Sala della Madonna for the event called "Spritz&Tramezzino." This informal session is designed as an opportunity for young people and the speaker to discuss their mutual scientific interests, the speaker’s career journey, prospects, and the secret recipe for the perfect Spritz.

If you would like to arrange a one-on-one meeting with Roberto, please let us know.

Join Zoom Meeting

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

Meeting ID: 824 8288 3288

Passcode: 072472

NEXT SEMINARS

General Seminar:

17/12 - Andrea Balestra

-----------2026------------

General Seminars:

15/01 - Olexandra Razim

22/01 - Margherita Talia

05/03 - Matteo Pais

Colloquium:

08/01 - Carlo Ferrigno

12/02 - Annalisa Bonafede

12/03 - Lucio Mayer

09/04 - Andrea Ferrara

14/05 - Stephen Mojzsis

11/06 - Daniel Apai

Other useful websites: https://indico.dfa.unipd.it/category/38/

Seminar Task Force: Elisabetta Rigliaco (elisabetta.rigliaco@inaf.it) Joel Beccarelli (joel.beccarelli@inaf.it)Domenico Barbato (domenico.barbato@inaf.it)Elena Carolo (elena.carolo@inaf.it) Alessandro Ignesti (alessandro.ignesti@inaf.it) Antonino Marasco (antonino.marasco@inaf.it)Alessandra Mastrobuono (alessandra.mastrobuono@unipd.it)Filippo Tusberti (filippo.tusberti@inaf.it)

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