Exploring MAXI J1744-294: IXPE insights into a Newly Discovered X-ray Transient

TL;DR

This study reports IXPE X-ray polarimetric observations of the transient black hole candidate MAXI J1744-294, setting upper limits on polarization and constraining the disk inclination during its soft state in 2025.

Contribution

First IXPE spectro-polarimetric observation of MAXI J1744-294, providing polarization constraints and disk inclination estimates for a newly discovered X-ray transient.

Findings

No significant polarization detected, upper limit of 1.3%.

Disk inclination constrained to less than 38-71 degrees.

Results consistent with soft-state black hole binaries at low to intermediate inclination.

Abstract

We present the first IXPE spectro-polarimetric observation of the black hole candidate MAXI J1744$-$294, a transient X-ray source discovered during a bright 2025 outburst in the Galactic center region. During the $\sim$150 ks observation, the source was found in the soft state, and its spectrum was well described by an absorbed multicolor disk with a minor high-energy tail. No significant polarization was detected, and we derived a 3$\sigma$ upper limit on the polarization degree of $1.3\%$ in the 2--8 keV energy band. This result is consistent with previous findings for soft-state black hole binaries observed at low to intermediate inclination angles. By comparing the polarization degree upper limit with theoretical predictions for standard accretion disk emission, we constrain the disk inclination to $i \lesssim 38^\circ$--$71^\circ$, depending on the black hole spin and the disk atmosphere albedo.