Searching for optical pulsations from spider millisecond pulsars with the fast photometer SiFAP2
Abstract
Optical pulsations from millisecond pulsars (MSPs) have recently been detected in a transitional MSP and an accreting MSP. Evidence for optical pulsations has also been found for a rotation-powered redback MSP. Observations suggest that optical pulsed emission is produced by different mechanisms depending on whether an accretion disk is present in the system. We explored a sample of rotation-powered MSPs in close binaries (Porb<1day; redbacks and black widows), searching for optical periodic signals with the SiFAP2 photometer mounted on the Telescopio Nazionale Galileo (TNG). We performed pulsation searches using the epoch-folding method with the most up-to-date (radio or gamma-ray) orbital solution for each system. These solutions were based either on previously published works or recent observations from Nançay, the Giant Metrewave Radio Telescope, the Parkes Observatory, and Fermi-LAT. We update or confirm radio and gamma-ray ephemerides for five of the presented systems. No optical pulsations were detected with a significance exceeding a 3σ confidence level in any of our searches, despite achieving sensitivities close to the instrument's limit. This places correspondingly stringent upper limits on the systems' optical pulsed magnitude and conversion efficiency. Our upper limits are consistent with the pulsed optical luminosity of optical pulsations from the redback PSR J2339-0533. Compared to accreting and transitional MSPs, redback and black widow systems show much lower efficiency in converting their spin-down power into pulsed optical emission. This supports the recent suggestion that the accretion disk around the neutron star plays a role in accelerating the particles responsible for producing bright optical pulsed emission.
Related
- The Origin of Isolated Millisecond Pulsars in Non-core-collapsed Globular Clusters
- Discovery of γ-Ray Pulsations from the Extreme-Spin-Down Millisecond Pulsar PSR J0435+3233
- Discovery of Gamma-Ray Pulsations from the Millisecond Pulsar PSR J0435+3233
- Modes in Transitional Millisecond Pulsars: Evidence of Pulsar Wind-Induced Disk Heating from GRMHD and Radiative Transfer
- A0538-66: A transient ultraluminous X-ray source with a relativistic outflow, 69,ms pulsations, and anomalous optical activity
BibTeX
@misc{malacaria2026searching,
title = {{Searching for optical pulsations from spider millisecond pulsars with the fast photometer SiFAP2}},
author = {Christian Malacaria and Alessandro Papitto and Filippo Ambrosino and Caterina Ballocco and Riccardo La Placa and Giulia Illiano and Arianna Miraval Zanon and Luigi Stella and Marco Turchetta and James D Turner and Clara Blanchard and Ignacio Cognard and Lucas Guillemot and Marta Burgay and Paolo d'Avanzo and Aleksandr Burtovoi and Andrea Sanna and Sergio Campana and Massimo Cecconi and Adriano Ghedina and Andrea Possenti and Diego Torres},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.02395},
eprint = {2609.02395},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05758448v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Searching for optical pulsations from spider millisecond pulsars with the fast photometer SiFAP2
AU - Christian Malacaria
AU - Alessandro Papitto
AU - Filippo Ambrosino
AU - Caterina Ballocco
AU - Riccardo La Placa
AU - Giulia Illiano
AU - Arianna Miraval Zanon
AU - Luigi Stella
AU - Marco Turchetta
AU - James D Turner
AU - Clara Blanchard
AU - Ignacio Cognard
AU - Lucas Guillemot
AU - Marta Burgay
AU - Paolo d'Avanzo
AU - Aleksandr Burtovoi
AU - Andrea Sanna
AU - Sergio Campana
AU - Massimo Cecconi
AU - Adriano Ghedina
AU - Andrea Possenti
AU - Diego Torres
PY - 2026
DA - 2026/09/22
PB - HAL
DO - 10.48550/arxiv.2609.02395
UR - https://hal.science/hal-05758448v1
AB - Optical pulsations from millisecond pulsars (MSPs) have recently been detected in a transitional MSP and an accreting MSP. Evidence for optical pulsations has also been found for a rotation-powered redback MSP. Observations suggest that optical pulsed emission is produced by different mechanisms depending on whether an accretion disk is present in the system. We explored a sample of rotation-powered MSPs in close binaries (P_orb<1day; redbacks and black widows), searching for optical periodic signals with the SiFAP2 photometer mounted on the Telescopio Nazionale Galileo (TNG). We performed pulsation searches using the epoch-folding method with the most up-to-date (radio or gamma-ray) orbital solution for each system. These solutions were based either on previously published works or recent observations from Nançay, the Giant Metrewave Radio Telescope, the Parkes Observatory, and Fermi-LAT. We update or confirm radio and gamma-ray ephemerides for five of the presented systems. No optical pulsations were detected with a significance exceeding a 3σ confidence level in any of our searches, despite achieving sensitivities close to the instrument's limit. This places correspondingly stringent upper limits on the systems' optical pulsed magnitude and conversion efficiency. Our upper limits are consistent with the pulsed optical luminosity of optical pulsations from the redback PSR J2339-0533. Compared to accreting and transitional MSPs, redback and black widow systems show much lower efficiency in converting their spin-down power into pulsed optical emission. This supports the recent suggestion that the accretion disk around the neutron star plays a role in accelerating the particles responsible for producing bright optical pulsed emission.
ER -