Formation and X-ray emission from hot bubbles in planetary nebulae - III. The impact of [Wolf-Rayet]-type winds

TL;DR

This study uses radiation-hydrodynamical simulations to explore how [Wolf-Rayet]-type winds influence hot bubble formation and X-ray emission in planetary nebulae, revealing higher X-ray luminosities but similar plasma temperatures across models.

Contribution

It introduces new models incorporating [WR] winds with updated mass-loss rates, showing their impact on hot bubble evolution and X-ray properties in planetary nebulae.

Findings

[WR] winds increase X-ray luminosity in models.

X-ray plasma temperature converges to 1-3 million K.

Mixing of gas phases is crucial for soft X-ray emission.

Abstract

We use radiation-hydrodynamical simulations to investigate the formation and synthetic X-ray emission of hot bubbles within planetary nebulae (PNe) driven by the powerful winds of H-deficient, [Wolf-Rayet]([WR])-type stars. Our models, based on {\sc mesa} stellar evolution tracks for 1--3 M$_{\odot}$ progenitors, adopt a recent mass-loss rate prescription for [WR] stars and incorporate the enhanced radiative cooling of their C-rich material, comparing the results against standard H-rich PN models. The enhanced mass-loss in the [WR] models leads to an accelerated post-AGB evolution and a subsequent delay in hot bubble formation compared to their H-rich counterparts, as suggested by a previous work. By computing synthetic X-ray spectra that account for the mixed H-rich and H-deficient gas phases, we find that models incorporating [WR] winds exhibit significantly higher X-ray luminosities ($L_\mathrm{X}$) than their H-rich counterparts, but the emissivity-weighted plasma temperature of the X-ray-emitting gas converge to values of $T_\mathrm{X} = [1-3] \times 10^{6}$~K, regardless of whether the system follows a [WR]-type or an H-rich post-AGB evolutionary path. Our results reinforce previous suggestions that mixing is a key mechanism in generating the observed soft X-ray emission even for PN hosting [WR] central stars.