A multiwavelength study of the new Galactic center black hole candidate MAXI J1744-294

Abstract: For the first time in nearly a decade, a new, bright transient was detected in the central parsec (pc) of the Galaxy. MAXI J1744-294 was never observed in outburst prior to January 2025. We present the results of a broadband, multi-wavelength study of this enigmatic source, including data from the NuSTAR, Chandra, XMM-Newton, Swift, and NICER X-ray telescopes, as well as complementary radio and near-infrared observations. We find that MAXI J1744-294 remained in the bright/soft state throughout the first months of 2025. Spectral hardening was observed in April 2025, followed by a decline in flux. Based on the spectral and temporal characteristics of the source, we identify MAXI J1744-294 as a candidate black hole (BH) low-mass X-ray binary (LMXB) $-$ the fourth candidate BH transient discovered within a (projected) distance of one pc from the Galactic supermassive black hole Sgr A*. This discovery provides further evidence for a cusp of BH-LMXBs in the central pc of our Galaxy, as argued for in previous observational work and suggested by analytical and theoretical work. Our multi wavelength study, involving a complementary range of observatories and spanning different outburst states, can serve as a model for future time domain astrophysics research.