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Tidal interaction can stop galactic bars : On the LMC non-rotating bar

Jiménez-Arranz LU and Roca-Fàbrega, S. LU orcid (2025) In Astronomy and Astrophysics 698.
Abstract

Context. The bar pattern speed of the LMC has been computed based on data from Gaia DR3 using three different methods. One method suggested that the LMC might be hosting a bar that barely rotates, and is slightly counter-rotating with respect to the disc of the LMC, with a pattern speed of Ωp = −1.0 ± 0.5 km s−1 kpc−1. Aims. We aim to confirm that tidal interactions might prevent the bar hosted by the LMC from rotating as a result of its interaction with the SMC. This might cause the bar in the LMC to slow down significantly until it (momentarily) stops. Methods. We analysed a subset of models (K9 and K21) from the KRATOS suite in which we detected non-rotating bars. We used two different methods to... (More)

Context. The bar pattern speed of the LMC has been computed based on data from Gaia DR3 using three different methods. One method suggested that the LMC might be hosting a bar that barely rotates, and is slightly counter-rotating with respect to the disc of the LMC, with a pattern speed of Ωp = −1.0 ± 0.5 km s−1 kpc−1. Aims. We aim to confirm that tidal interactions might prevent the bar hosted by the LMC from rotating as a result of its interaction with the SMC. This might cause the bar in the LMC to slow down significantly until it (momentarily) stops. Methods. We analysed a subset of models (K9 and K21) from the KRATOS suite in which we detected non-rotating bars. We used two different methods to track the evolution of the bar pattern speed: the program patternSpeed.py and temporal finite-differences of the change in the rate in the major axis of the phase angle of the bar. Results. In the second LMC–SMC-like pericenter passage of K9, the bar of the LMC-like galaxy weakens so much as to almost disappear and regenerates with a pattern speed that slows down from Ωp ∼ 20 km s−1 kpc−1 to Ωp ∼ 0 km s−1 kpc−1 in less than 75 Myr. Then, the bar rotates at less than Ωp ∼ 3−5 km s−1 kpc−1 for about 100 Myr, until it recovers the initial (before the interaction) pattern speed of Ωp ∼ 10 km s−1 kpc−1. The results for the K21 simulation are similar. Conclusions. We show that galactic bars can be slowed down or even stopped by tidal interaction. This strengthens the hypothesis that the LMC hosts a non-rotating bar, and it can be an alternative formation scenario for other observed slowly rotating bars.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
galaxies: interactions, Galaxy: kinematics and dynamics, Magellanic Clouds
in
Astronomy and Astrophysics
volume
698
article number
L7
publisher
EDP Sciences
external identifiers
  • scopus:105007108371
ISSN
0004-6361
DOI
10.1051/0004-6361/202555019
language
English
LU publication?
yes
id
5ac6e8fa-57a4-4be4-a094-20416efdae55
date added to LUP
2025-07-30 10:27:22
date last changed
2025-07-30 10:28:15
@article{5ac6e8fa-57a4-4be4-a094-20416efdae55,
  abstract     = {{<p>Context. The bar pattern speed of the LMC has been computed based on data from Gaia DR3 using three different methods. One method suggested that the LMC might be hosting a bar that barely rotates, and is slightly counter-rotating with respect to the disc of the LMC, with a pattern speed of Ω<sub>p</sub> = −1.0 ± 0.5 km s<sup>−1</sup> kpc<sup>−1</sup>. Aims. We aim to confirm that tidal interactions might prevent the bar hosted by the LMC from rotating as a result of its interaction with the SMC. This might cause the bar in the LMC to slow down significantly until it (momentarily) stops. Methods. We analysed a subset of models (K9 and K21) from the KRATOS suite in which we detected non-rotating bars. We used two different methods to track the evolution of the bar pattern speed: the program patternSpeed.py and temporal finite-differences of the change in the rate in the major axis of the phase angle of the bar. Results. In the second LMC–SMC-like pericenter passage of K9, the bar of the LMC-like galaxy weakens so much as to almost disappear and regenerates with a pattern speed that slows down from Ω<sub>p</sub> ∼ 20 km s<sup>−1</sup> kpc<sup>−1</sup> to Ω<sub>p</sub> ∼ 0 km s<sup>−1</sup> kpc<sup>−1</sup> in less than 75 Myr. Then, the bar rotates at less than Ω<sub>p</sub> ∼ 3−5 km s<sup>−1</sup> kpc<sup>−1</sup> for about 100 Myr, until it recovers the initial (before the interaction) pattern speed of Ω<sub>p</sub> ∼ 10 km s<sup>−1</sup> kpc<sup>−1</sup>. The results for the K21 simulation are similar. Conclusions. We show that galactic bars can be slowed down or even stopped by tidal interaction. This strengthens the hypothesis that the LMC hosts a non-rotating bar, and it can be an alternative formation scenario for other observed slowly rotating bars.</p>}},
  author       = {{Jiménez-Arranz and Roca-Fàbrega, S.}},
  issn         = {{0004-6361}},
  keywords     = {{galaxies: interactions; Galaxy: kinematics and dynamics; Magellanic Clouds}},
  language     = {{eng}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Tidal interaction can stop galactic bars : On the LMC non-rotating bar}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202555019}},
  doi          = {{10.1051/0004-6361/202555019}},
  volume       = {{698}},
  year         = {{2025}},
}