The SN 2023ixf Progenitor in M101: I. Infrared Variability

Observational evidence points to a red supergiant (RSG) progenitor for SN 2023ixf. The progenitor candidate has been detected in archival images at wavelengths (>0.6 micron) where RSGs typically emit profusely. This object is distinctly variable in the infrared (IR). We characterize the variabili...

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Bibliographic Details
Published in:arXiv.org 2023-08
Main Authors: Soraisam, Monika D, Szalai, Tamás, Van Dyk, Schuyler D, Andrews, Jennifer E, Srinivasan, Sundar, Sang-Hyun, Chun, Matheson, Thomas, Scicluna, Peter, Vasquez-Torres, Diego A
Format: Article
Language:English
Subjects:
Astronomical models
Empirical analysis
Gaussian process
Light curve
Luminosity
Near infrared radiation
Red giant stars
Stellar evolution
Supergiant stars
Variability
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Summary:Observational evidence points to a red supergiant (RSG) progenitor for SN 2023ixf. The progenitor candidate has been detected in archival images at wavelengths (>0.6 micron) where RSGs typically emit profusely. This object is distinctly variable in the infrared (IR). We characterize the variability using pre-explosion mid-IR (3.6 and 4.5 micron) Spitzer and ground-based near-IR (JHKs) archival data jointly covering 19 yr. The IR light curves exhibit significant variability with RMS amplitudes in the range of 0.2-0.4 mag, increasing with decreasing wavelength. From a robust period analysis of the more densely sampled Spitzer data, we measure a period of 1091+/-71 days. We demonstrate using Gaussian Process modeling that this periodicity is also present in the near-IR light curves, thus indicating a common physical origin, which is likely pulsational instability. We use a period-luminosity relation for RSGs to derive a value of M_K=-11.58+/-0.31 mag. Assuming a late M spectral type, this corresponds to log(L/L_sun)=5.27+/-0.12 at T_eff=3200 K and to log(L/L_sun)=5.37+/-0.12 at T_eff=3500 K. This gives an independent estimate of the progenitor's luminosity, unaffected by uncertainties in extinction and distance. Assuming the progenitor candidate underwent enhanced dust-driven mass-loss during the time of these archival observations, and using an empirical period-luminosity-based mass-loss prescription, we obtain a mass-loss rate of around (2-4)x10^-4 M_sun/yr. Comparing the above luminosity with stellar evolution models, we infer an initial mass for the progenitor candidate of 20+/-4 M_sun, making this one of the most massive progenitors for a Type II SN detected to-date.
ISSN:2331-8422