Emission outside the radio band is predicted for most models trying to explain the FRB phenomenon. Its nature, however, is still to be determined, with the exception of the possible example provided by the Galactic FRB20200428A, where X-ray emission was observed simultaneously with the radio emission, with an energy ratio E_X/E_radio = 10^5.
I will review the targeted attempts to search for...
The first Chinese X-ray mission, Insight Hard X-ray Modulation Telescope (Insight-HXMT), carries on board three collimator-based instruments, which altogether cover the range 1-250 keV. In addition, the High-Energy (HE) instrument works as an open-sky monitor in the 0.2-3 MeV. In this talk I report two main contributions of Insight-HXMT: a) thanks to the unique combination of large effective...
Up to date, there is only one FRB counterpart observed in hard X-rays. Bursts from a peculiar magnetar SGR 1935+2154 associated with FRB 200428, detected by INTEGRAL. In this work, an extensive search for hard X-ray bursts below the automatic INTEGRAL ISGRI-IBIS detection threshold that would be spatially and temporally coincident with the activity of recently active FRB repeaters has been...
Repeating FRBs are ideal targets for multi-wavelength observational campaigns aiming at potential counterparts. We are monitoring FRB 20220912A, one of the most active repeaters, using the fast optical photon counters Aqueye+ and Iqueye at the Asiago Observatory. We are trying to characterize foreground/background events by analyzing archival Aqueye+ data taken on other fields. To this purpose...
High-time-resolution detectors are playing a crucial role in advancing our understanding of fast transient events enabling precise measurements of their properties. SiFAP2, a state-of-the-art high-speed optical photometer permanently mounted at the 3.6m INAF Telescopio Nazionale Galileo (TNG) paved the way for significant breakthroughs in optical observations, especially on neutron stars. This...
The AGILE space mission, with its unique features (two coaligned imaging X- and gamma-ray detectors, a non-imaging calorimeter, and
the observing capability to cover about 80% if the sky in 7 minutes), participated to all the recent campaign searches for electromagnetic
(e.m.) counterparts of multi messenger events (gravitational waves and neutrinos), but also to high-energy counterparts...
We report on a comprehensive search for X-ray and Gamma-ray counterparts to a selected sample of repeating FRBs using AGILE data. Focusing on events with an excess dispersion measure below 300 pc cm⁻³, our high-resolution analysis with the AGILE MiniCalorimiter (MCAL) did not reveal any significant X-ray emission, enabling us to set robust upper limits on the flux above 400 keV within a...
Giant pulses (GPs) are very energetic and impulsive phenomena, with flux densities up to few MJy and pulse widths from ~100 ns to ~100 µs, as observed from the Crab pulsar. The GPs observed from the Crab pulsar can be used to study the energy distribution and their dynamic spectra can address the emission mechanisms of neutron stars. Some fast radio bursts (FRBs) models involve neutron stars...
