Transitional millisecond pulsars (tMSPs) bridge the gap between accreting neutron stars in low-mass X-ray binaries and millisecond radio pulsars, offering a unique laboratory to study the interplay between accretion and pulsar activity. These systems exhibit a subluminous X-ray state characterized by alternating high, low and flaring emission modes.
Multi-wavelength campaigns on the prototype...
X-ray binaries are key laboratories for studying accretion and jet ejection mechanisms in strong gravitational fields. Among them, Cygnus X-3 stands out due to its distinctive properties and long-standing observational interest. In this talk, I will present results from the second and third observations of Cygnus X-3 by the Imaging X-ray Polarimetry Explorer (IXPE), focusing on the evolution...
MAXI J1744–294 is a bright X-ray transient discovered in early January 2025 within 20″ of Sgr A* by MAXI/GSC. Multi-instrument follow-up observations established it as a black hole low-mass X-ray binary in outburst, with a soft-state spectrum characterized by strong absorption, a disk component, a steep power-law tail, and a prominent Fe K$\alpha$ line, albeit with possible contamination from...
In this talk, I’ll present the results of a comprehensive, 3-year-long multiwavelength polarimetric campaign on the prototypical black hole X-ray binary Cygnus X-1, conducted between 2022 and 2024. Using data from the Imaging X-ray Polarimetry Explorer (IXPE), we measured X-ray polarization 13 times across both hard and soft spectral states. We found that the polarization degree in the hard...
Accreting, weakly magnetized Neutron Stars in Low-mass X-ray binaries (NS-LMXBs) are a fundamental laboratory to study radiation processes in the strong gravity regime. Z-sources are NS-LMXBs characterized by a wide Z-like three branches track in the Color-Color Diagram, typically accreting close to the Eddington limit.
In this talk, we discuss the spectro-polarimetric results obtained by...
X-ray polarimetry is a fine tool for probing the accretion geometry and physical processes operating in the proximity of compact objects, such as black holes and neutron stars. Recent discoveries made by the Imaging X-ray Polarimetry Explorer question our
understanding of the accretion picture. The observed high levels of X-ray polarization in X-ray binaries and its properties are challenging...
The geometry of the corona in accreting black hole binaries remains a central puzzle in high-energy astrophysics, particularly during their outburst phases when dramatic structural changes occur. Two powerful observational tools available—X-ray reverberation mapping and X-ray polarization—now offer complementary but seemingly conflicting insights into the innermost regions around black holes....
