The X-ray Luminous Type Ibn SN 2022ablq: Estimates of Pre-explosion Mass Loss and Constraints on Precursor Emission

Type Ibn supernovae (SNe Ibn) are rare stellar explosions powered primarily by interaction between the SN ejecta and H-poor, He-rich material lost by their progenitor stars. Multi-wavelength observations, particularly in the X-rays, of SNe Ibn constrain their poorly-understood progenitor channels and mass-loss mechanisms. Here we present Swift X-ray, ultraviolet, and ground-based optical observations of the Type Ibn SN 2022ablq -- only the second SN Ibn with X-ray detections to date. While similar to the prototypical Type Ibn SN 2006jc in the optical, SN 2022ablq is roughly an order of magnitude more luminous in the X-rays, reaching unabsorbed luminosities LX ~ 3×10⁴⁰ erg s⁻¹ between 0.2 - 10 keV. From these X-ray observations we infer time-varying mass-loss rates between 0.05 - 0.5 M_ yr⁻¹ peaking 0.5 - 2 yr before explosion. This complex mass-loss history and circumstellar environment disfavor steady-state winds as the primary progenitor mass-loss mechanism. We also search for precursor emission from alternative mass-loss mechanisms, such as eruptive outbursts, in forced photometry during the two years before explosion. We find no statistically significant detections brighter than M ≈ -14 -- too shallow to rule out precursor events similar to those observed for other SNe Ibn. Finally, numerical models of the explosion of a ~15 M_ helium star that undergoes an eruptive outburst ≈1.8 years before explosion are consistent with the observed bolometric light curve. We conclude that our observations disfavor a Wolf-Rayet star progenitor losing He-rich material via stellar winds and instead favor lower-mass progenitor models, including Roche-lobe overflow in helium stars with compact binary companions or stars that undergo eruptive outbursts during late-stage nucleosynthesis stages.