Millisecond pulsars (MSPs) are unique laboratories for probing the properties of matter at supra-nuclear densities (Equation of State, EoS), by determining the stability of neutron stars (NSs) against break-up from extreme spin. The quickest rotating NSs are prime targets for continuous gravitational wave (CW) emission, which can be enabled by an asymmetric structure. The GEMS project was conceived at the intersection of innovative observational strategies in the gravitational and electromagnetic (EM) domains. A key focus was to obtain the accurate EM spin and orbital parameters necessary to maximise the sensitivity of CW searches in LIGO-Virgo data.
GEMS leveraged the sensitivity gain offered by dedicated hardware (e.g., the SiFAP2 instrument at INAF/TNG) to perform high-time resolution optical surveys of candidate CW sources like bright accreting NSs in Low-Mass X-ray Binaries and MSPs. It performed a survey of potential optical millisecond pulsars in a multiwavelength context, including observations also in the radio, UV, X-ray and gamma-rays, bringing the total number of detected systems to three and identified promising candidates. This result advances our understanding of how an accretion disk or pulsar magnetosphere accelerates particles and amplifies the optical signal in these systems. Furthermore, GEMS pioneered the use of X-ray polarimetry to study accreting MSPs. By contributing to the first measurement of X-ray polarisation from an accreting MSP, the project provided a powerful new probe for constraining the geometry of the magnetic fields and emission regions. This geometric information is vital for breaking parameter degeneracies in pulse profile modeling, thus extending the possibility of accurately constraining the NS mass and radius, which directly informs the EoS. Fast optical photometry can also play a key role to test models that explain the phenomenology of certain Fast Radio Bursts in terms of fast-spinning magnetars.
This workshop will gather experts from multi-wavelength and multi-messenger astrophysics to present and discuss the key results of the GEMS research project. It is aimed to synthesise the project's observational and theoretical outcomes, share the validated search algorithms and improved hardware solutions, and collectively plan the necessary future observing strategies that will push the boundaries of NS fundamental physics with next-generation detectors.
The conference will take place from Wednesday 13 May to Friday 15 May 2026 at the INAF-Observatory of Rome.
