Supernova Shocks Cannot Explain the Inflated State of Hypervelocity Runaways from White Dwarf Binaries

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Auteurs principaux: Bhat, Aakash, Bauer, Evan B., Pakmor, Rüdiger, Shen, Ken J., Caiazzo, Ilaria, Rajamuthukumar, Abinaya Swaruba, El-Badry, Kareem, Kerzendorf, Wolfgang E.
Format: Preprint
Publié: 2024
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author Bhat, Aakash
Bauer, Evan B.
Pakmor, Rüdiger
Shen, Ken J.
Caiazzo, Ilaria
Rajamuthukumar, Abinaya Swaruba
El-Badry, Kareem
Kerzendorf, Wolfgang E.
author_facet Bhat, Aakash
Bauer, Evan B.
Pakmor, Rüdiger
Shen, Ken J.
Caiazzo, Ilaria
Rajamuthukumar, Abinaya Swaruba
El-Badry, Kareem
Kerzendorf, Wolfgang E.
contents Recent observations have found a growing number of hypervelocity stars with speeds of $\approx 1500-2500\,$km\,s$^{-1}$ which could have only been produced through thermonuclear supernovae in white dwarf binaries. Most of the observed hypervelocity runaways in this class display a surprising inflated structure: their current radii are roughly an order of magnitude greater than they would have been as white dwarfs filling their Roche lobe. While many simulations exist studying the dynamical phase leading to supernova detonation in these systems, no detailed calculations of the long-term structure of the runaways have yet been performed. We use an existing \textsc{Arepo} hydrodynamical simulation of a supernova in a white dwarf binary as a starting point for the evolution of these stars with the 1 dimensional stellar evolution code MESA. We show that the supernova shock is not enough to inflate the white dwarf over timescales longer than a few thousand years, significantly shorter than the $10^{5-6}$ year lifetimes inferred for observed hypervelocity runaways. Despite experiencing a shock from a supernova less than $\approx 0.02\,R_\odot$ away, our models do not experience significant interior heating, and all contract back to radii around $0.01\,R_\odot$ within about $10^4$\,years. Explaining the observed inflated states requires either an additional source of significant heating or some other physics that is not yet accounted for in the subsequent evolution.
format Preprint
id arxiv_https___arxiv_org_abs_2407_03424
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Supernova Shocks Cannot Explain the Inflated State of Hypervelocity Runaways from White Dwarf Binaries
Bhat, Aakash
Bauer, Evan B.
Pakmor, Rüdiger
Shen, Ken J.
Caiazzo, Ilaria
Rajamuthukumar, Abinaya Swaruba
El-Badry, Kareem
Kerzendorf, Wolfgang E.
Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
Recent observations have found a growing number of hypervelocity stars with speeds of $\approx 1500-2500\,$km\,s$^{-1}$ which could have only been produced through thermonuclear supernovae in white dwarf binaries. Most of the observed hypervelocity runaways in this class display a surprising inflated structure: their current radii are roughly an order of magnitude greater than they would have been as white dwarfs filling their Roche lobe. While many simulations exist studying the dynamical phase leading to supernova detonation in these systems, no detailed calculations of the long-term structure of the runaways have yet been performed. We use an existing \textsc{Arepo} hydrodynamical simulation of a supernova in a white dwarf binary as a starting point for the evolution of these stars with the 1 dimensional stellar evolution code MESA. We show that the supernova shock is not enough to inflate the white dwarf over timescales longer than a few thousand years, significantly shorter than the $10^{5-6}$ year lifetimes inferred for observed hypervelocity runaways. Despite experiencing a shock from a supernova less than $\approx 0.02\,R_\odot$ away, our models do not experience significant interior heating, and all contract back to radii around $0.01\,R_\odot$ within about $10^4$\,years. Explaining the observed inflated states requires either an additional source of significant heating or some other physics that is not yet accounted for in the subsequent evolution.
title Supernova Shocks Cannot Explain the Inflated State of Hypervelocity Runaways from White Dwarf Binaries
topic Solar and Stellar Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2407.03424