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Compact Objects in the Magellanic System

Stellar evolution in interacting galaxies

Figure 2: (a) Gaia positions of the stars in the LMC, SMC, and the Magellanic Bridge (Image credit: ESA/Gaia/DPAC) (b) the proper motion of the old stars in the Magellanic Bridge indicating the flow of stellar objects from the SMC to the LMC. The black marker and the arrow originating from it represents the position and the direction of proper motion of the first ever supersoft Symbiotic binary eRASSU J043115.8-711730 (J0431-71, Saha et al. 2026) in the Magellanic Bridge respectively. The brown arrows in each cell delineated by the dashed line is the average proper motion of the stars in the corresponding cell. (c) RGB false color image from XMM-Newton offering a closer look of the field around J0431-71. (d) the mechanism that drives the multi-wavelength variability in J0431-71 where a pulsating red-giant induces a Roche lobe overflow from the star to the white-dwarf.

The Magellanic Clouds and the Magellanic Bridge provide a unique template for studying X-ray binary populations at known distances and sub-solar metallicities. I am a member of the eROSITA German Consortium and work closely with the Compact Objects Working group to identify and characterise the endpoints of stellar evolution — neutron stars, white dwarfs, and black holes — in binary systems using eROSITA all-sky survey (eRASS) data. I combine X-ray spectral analysis with multiwavelength observations, including optical spectroscopy, long-term optical/IR photometry, and kinematic data from Gaia, to identify and classify optical counterparts. My current work focuses on compact-object-powered X-ray sources in the Magellanic Bridge, including symbiotic X-ray binaries (Saha et al. 2026, Fig. 2), low-mass X-ray binaries, and super-soft sources. Using a continuous time-domain approach, I aim to build a more complete census of X-ray binaries in the Magellanic Bridge and use these systems to trace the history of stellar evolution in a dynamic environment shaped by the tidal interaction between the LMC and SMC. Classifying X-ray sources in crowded fields requires robust probabilistic cross-matching of X-ray catalogues with multiwavelength surveys. I develop and apply positional cross-matching pipelines and isochrone-based photometric classification methods to distinguish compact-object populations in the Local Group from background AGNs and foreground stars.