Journal of High Energy Astrophysics
02/2026
JHEAp
X-ray emission of the Nuclear Stellar Disk as seen by SRG/ART-XC
Незабудкин, В.
Кривонос, Р.
Сазонов, С.
Буренин, Р.
Лутовинов, А.
The Nuclear Stellar Disk (NSD), together with the Nuclear Stellar Cluster and the supermassive black hole Sgr A*, forms the central region of the Milky Way. Galactic X-ray background emission is known to be associated with the old stellar population, predominantly produced by accreting white dwarfs. In this work we characterize the X-ray emission of the Galactic Center (GC) region using wide-field observations with the ART-XC telescope on-board the SRG observatory in the 4‑12 keV energy band. Our analysis demonstrates that the X-ray emission of the GC at a spatial scale of a few hundred parsecs is dominated by the regularly-shaped NSD aligned in the Galactic plane, and characterized by latitudinal and longitudinal scale heights of ∼20 pc and ∼100 pc, respectively. The measured flux (6.8‑0.3+0.1)×10‑10erg s‑1 cm‑2 in the 4‑12 keV band corresponds to a luminosity of L4–12keV=(5.9‑0.3+0.1)×1036erg s‑1, assuming the GC distance of 8.178 kpc. The average mass-normalized X-ray emissivity of the NSD, 〈L/M〉=(5.6‑0.7+0.5)×1027erg s‑1 M⊙‑1, exceeds the corresponding value for the Galactic ridge by a factor of 3.3‑0.5+0.4, confirming other studies. We also perform a deprojection of the observed NSD surface brightness distribution in order to construct a three-dimensional X-ray luminosity density model, which can be directly compared to the existing 3D stellar mass models. Finally, we conclude that the spatial distribution of the X-ray emission from the NSD is consistent with the most recent stellar mass density distribution model within 30%, which suggests that this emission is dominated by unresolved point X-ray sources rather than by diffuse X-ray emission.
