Star-Disk Collisions: Implications for Quasi-periodic Eruptions and Other Transients Near Supermassive Black Holes

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Main Authors: Yao, Philippe Z., Quataert, Eliot, Jiang, Yan-Fei, Lu, Wenbin, White, Christopher J.
Format: Preprint
Published: 2024
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_version_ 1866915082963779584
author Yao, Philippe Z.
Quataert, Eliot
Jiang, Yan-Fei
Lu, Wenbin
White, Christopher J.
author_facet Yao, Philippe Z.
Quataert, Eliot
Jiang, Yan-Fei
Lu, Wenbin
White, Christopher J.
contents We use Athena++ to study the hydrodynamics of repeated star-accretion disk collisions close to supermassive black holes, and discuss their implications for the origin of quasi-periodic eruptions (QPEs) and other repeating nuclear transients. We quantify the impact of the collisions on the stellar structure, the amount of stripped stellar debris, and the debris' orbital properties. We provide simple fitting functions for the stellar mass-loss per collision; the mass-loss is much larger after repeated collisions due to the dilute stellar atmosphere shock-heated in earlier collisions. The lifetime of the QPE-emitting phase set by stellar mass-loss in star-disk collision models for QPEs is thus at most ~1000 years; it is shortest for eRO-QPE2, of order a few decades. The mass of the stripped stellar debris per collision and its orbital properties imply that currently observed QPEs are not powered by direct star-disk collisions but rather by collisions between the stellar debris liberated in previous collisions and the accretion disk (`circularization shocks'). We discuss how the hydrodynamics of this interaction can explain the diverse timing properties of QPEs including the regular timing of GSN 069 and eRO-QPE2 and the large flare-to-flare timing variations observed in eRO-QPE1. QPEs with recurrence times of many days, if observed, may have more regular timing.
format Preprint
id arxiv_https___arxiv_org_abs_2407_14578
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Star-Disk Collisions: Implications for Quasi-periodic Eruptions and Other Transients Near Supermassive Black Holes
Yao, Philippe Z.
Quataert, Eliot
Jiang, Yan-Fei
Lu, Wenbin
White, Christopher J.
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
We use Athena++ to study the hydrodynamics of repeated star-accretion disk collisions close to supermassive black holes, and discuss their implications for the origin of quasi-periodic eruptions (QPEs) and other repeating nuclear transients. We quantify the impact of the collisions on the stellar structure, the amount of stripped stellar debris, and the debris' orbital properties. We provide simple fitting functions for the stellar mass-loss per collision; the mass-loss is much larger after repeated collisions due to the dilute stellar atmosphere shock-heated in earlier collisions. The lifetime of the QPE-emitting phase set by stellar mass-loss in star-disk collision models for QPEs is thus at most ~1000 years; it is shortest for eRO-QPE2, of order a few decades. The mass of the stripped stellar debris per collision and its orbital properties imply that currently observed QPEs are not powered by direct star-disk collisions but rather by collisions between the stellar debris liberated in previous collisions and the accretion disk (`circularization shocks'). We discuss how the hydrodynamics of this interaction can explain the diverse timing properties of QPEs including the regular timing of GSN 069 and eRO-QPE2 and the large flare-to-flare timing variations observed in eRO-QPE1. QPEs with recurrence times of many days, if observed, may have more regular timing.
title Star-Disk Collisions: Implications for Quasi-periodic Eruptions and Other Transients Near Supermassive Black Holes
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2407.14578