Probing habitable regions with SRG/eROSITA

Stellar high-energy radiation is a key driver of atmospheric erosion and evolution in exoplanets, directly affecting their long-term habitability. We present a comprehensive study on stellar high-energy radiation and its impact on exoplanetary atmospheres, leveraging data from the $\mathit{\text{SRG/eROSITA}}$ all-sky survey. Our sample consists of 3750 main-sequence stars identified by cross-matching with $\mathit{\text{Gaia}}$ DR3. Utilizing X-ray spectral fits from the $\mathit{\text{eROSITA}}$ catalog, we computed X-ray ($L_X$) and combined extreme-ultraviolet (EUV) luminosities ($L_{\mathrm{E}\mathrm{U}\mathrm{V}}$), which we used to derive XUV fluxes at the habitable zone ($F_{\mathrm{X}\mathrm{U}\mathrm{V},\mathrm{H}\mathrm{Z}}$). We find that the majority of stars in our sample are significantly more XUV-active than the Sun, with habitable zone fluxes ranging from ${10}^0$ to ${10}^5$ erg~cm${}^{-2}$~s${}^{-1}$. The ratio of $L_{\mathrm{X}\mathrm{U}\mathrm{V}}\mathrm{/}{L}_{\mathrm{b}\mathrm{o}\mathrm{l}}$ is found to be higher for cooler, magnetically active stars, highlighting their potentially hazardous nature for planetary atmospheres. Applying the energy-limited escape model, we computed atmospheric mass-loss rates for hypothetical earth-like planets located at the habitable zone of each star. We also present local maps for distances up to $500$~pc of the average XUV flux, revealing ``hazard zones’’ where stellar radiation could significantly influence planetary atmospheric evolution. This work demonstrates the power of X-ray surveys in constraining the high-energy environments of exoplanets and underscores the critical role of stellar activity in planetary habitability.