Speaker
Description
Recent studies based on XMM-Newton and SRG/ART-XC observations have reported an excess of X-ray emission per unit stellar mass in the Nuclear Stellar Disk (NSD) compared to regions farther from the Galactic Center. These results are based on hard X-ray measurements (4-12 keV) and studies of the Fe XXV emission line at 6.7 keV. In this work, we investigate the population of faint X-ray sources in the NSD using deep Chandra observations (peak exposure $\sim$800 ks) in the 4-8 keV band. In the region of highest sensitivity, 546 sources are detected within an area of 25 arcmin$^2$. We construct the source number-flux distribution (dN/dS) and compare it with model predictions based on the luminosity function of the Solar neighborhood, as well as with previous logN-logS measurements in the Norma region. We find good agreement between our data, the model, and the Norma region results across the entire flux range probed by the observations, down to the sensitivity limit of $\sim 2.2 \times 10^{-15}$ erg $s^{-1}$ $cm^{-2}$. Our results indicate that the detected source population in the NSD remains consistent with the expected stellar population, dominated by Cataclysmic Variables (CVs) and Active Binaries (ABs) down to the observation's sensitivity limit. This suggests that the reported emissivity excess in the NSD either arises from a population of even fainter sources below our detection threshold or requires a different physical interpretation, such as a contribution from a truly diffuse component.