«A Microquasar Odyssey: Unveiling the Complexities»

IXPE’s First Look at the Newly Discovered Black Hole Binary MAXI J1744–294

Not scheduled

15m

Palazzo Municipale - Sala delle Capriate (Cefalù (Palermo))

Talk Talk Polarimetry (X-ray, Optical, Radio…)

Speaker

Lorenzo Marra (Istituto Nazionale di Astrofisica (INAF))

Description

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 diffuse Galactic center emission. We report on the first Imaging X-ray Polarimetry Explorer (IXPE) observation of MAXI J1744–294, carried out over April 5–8, 2025, for a total exposure of 150 ks. In the 2–8 keV band, the measured polarization degree remained below the observation Minimum Detectable Polarization, resulting in an upper limit of PD < 1.3%. This non-detection is in line with expectations for a thermal-dominated accretion disk viewed at low‐to‐intermediate inclination. We discuss how polarimetric measurements can help constrain key disk parameters such as inclination and the BH spin.