Chandra’s Insights into SN 2023ixf

Abstract

We report Chandra-ACIS observations of supernova (SN) 2023ixf in M101 on day 13 and 86 since the explosion. The X-rays in both epochs are characterized by high-temperature plasma from the forward shocked region as a result of circumstellar interaction. We are able to constrain the absorption column density at both Chandra epochs, which is much larger than that due to the Galactic and host absorption column, and we attribute it to absorption by the circumstellar matter in the immediate vicinity of SN 2023ixf. Combining our column density measurements with the published measurement on day 4, we show that the column density declines as t −2 between day 4 to day 13 and then evolves as t −1. The unabsorbed 0.3–10 keV luminosity evolves as t −1 during the Chandra epochs. On the Chandra first epoch observation, when the SN was 13 days old, we detect the Fe Kα fluorescent line at 6.4 keV indicating presence of cold material in the vicinity of the supernova. The line is absent on day 86, consistent with the decreased column density by a factor of 7 between the two epochs. Our analysis indicates that during 10–1.5 yr before explosion, the progenitor was evolving with a constant mass-loss rate of 5.6 × 10−4 M ⊙ yr−1.

Final Moments. II. Observational Properties and Physical Modeling of Circumstellar-material-interacting Type II Supernovae

“…In this case, high mass-loss rates (e.g., ∼10 −2 M e yr −1 ) could still be inferred from electron scattering of recombination photons in dense parts of CSM, while lowerdensity material along different lines of sight would still allow typical ejecta velocities of ∼10 4 km s −1 , with little to no deceleration by dense CSM. This physical picture may also be able to explain the discrepancies in the derived mass-loss rates between UV/optical versus X-ray/radio observations of SN 2023ixf (Berger et al 2023;Chandra et al 2024;Grefenstette et al 2023;Jacobson-Galán et al 2023;Matthews et al 2023;Nayana et al 2024, in prep.). Furthermore, a deviation from a steady-state CSM density profile (ρ ∝ r −2 ) in these models may be necessary to adequately match the early time light-curve slope (e.g., SN 2023ixf; Jacobson-Galán et al 2023;Hiramatsu et al 2023).…”

The SN 2023ixf Progenitor in M101. II. Properties

“…Smith et al (2023), Vasylyev et al (2023), and Li et al (2024) presented evidence for asymmetry in the CSM and the SN ejecta. Further signs of early CSM interaction at other wavelengths include the detection of the SN in X-rays (up to 20 keV) at several epochs, starting about 4 days after explosion and beyond (Chandra et al 2023b;Grefenstette et al 2023;Mereminskiy et al 2023;Chandra et al 2024), as well as, after initial radio and submillimeter nondetections (Chandra et al 2023a;Berger et al 2023), detection at centimeter wavelengths ∼29 days postdiscovery (Matthews et al 2023). Early attempts were made to detect the SN in γ-rays (Ravensburg et al 2024) and neutrinos (Guetta et al 2023;Thwaites et al 2023), with null results.…”