Analysis of 14 Years of X-Ray Emission From SN 2011DH

Ejecta from core-collapse supernovae interact with the circumstellar medium shed by the progenitor star, producing X-ray emission. Previous studies analyzed the X-ray spectrum of the Type IIb supernova SN 2011dh up to 500 days after explosion. Long-term monitoring of X-ray emission provides valuable constraints on supernova evolution and progenitor systems, yet such studies remain rare for Type IIb events due to limited data. Here we present the most comprehensive X-ray light curve of SN 2011dh to date, combining all available Chandra and XMM-Newton data with previously published and newly released Swift observations, extending coverage to 5100 days. We measure a luminosity decline proportional to t$^{-0.74 \pm 0.04}$ and infer a mass-loss rate of $(1.0-2.2) \times 10^{-6}$ solar masses per year for $v_w = 10$ km/s, or $(2.0-4.4) \times 10^{-6} $ solar masses per year for $v_w = 20$ km/s. These estimates agree with earlier results, supporting the interpretation that the X-ray emission has been dominated by an adiabatic reverse shock. The consistency of our late-time results with previous studies demonstrates that SN 2011dh has evolved steadily for nearly 14 years.