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Galactic seismology: can the Gaia ‘phase spiral’ co-exist with a clumpy, turbulent interstellar medium?

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Titel: Galactic seismology: can the Gaia ‘phase spiral’ co-exist with a clumpy, turbulent interstellar medium?
Autoren: Tepper-García, Thor, Bland-Hawthorn, Joss, Bedding, Timothy R., Federrath, Christoph, Agertz, Oscar
Weitere Verfasser: Lund University, Profile areas and other strong research environments, Strategic research areas (SRA), eSSENCE: The e-Science Collaboration, Lunds universitet, Profilområden och andra starka forskningsmiljöer, Strategiska forskningsområden (SFO), eSSENCE: The e-Science Collaboration, Originator, Lund University, Faculty of Science, Department of Physics, Astrophysics, Lunds universitet, Naturvetenskapliga fakulteten, Fysiska institutionen, Astrofysik, Originator
Quelle: Monthly Notices of the Royal Astronomical Society. 542(3):1987-2003
Schlagwörter: Natural Sciences, Physical Sciences, Astronomy, Astrophysics and Cosmology, Naturvetenskap, Fysik, Astronomi, astrofysik och kosmologi
Beschreibung: The Gaia satellite revealed a remarkable spiral pattern (‘phase spiral’, PS) in the z–Vz phase–plane throughout the solar neighbourhood, where z and Vz are the displacement and velocity of a star perpendicular to the Galactic plane. As demonstrated by many groups, the kinematic signature reflects the Galactic stellar disc’s response to a dynamical disturbance some 0.3–3 Gyr ago. However, previous controlled simulations did not consider the impact of the multiphase interstellar medium (ISM) on the existence of the PS. This is crucial because it has been suggested that this weak signal is highly susceptible to scattering by small-scale density fluctuations typical of the ISM. This has motivated us to explore the formation and fate of the PS in a suite of high-resolution, N-body/hydrodynamical simulations of an idealized Galaxy analogue bearing a realistic ISM that interacts impulsively with a massive perturber. In our models, high-gas surface densities within the disc encourage vigorous star formation, which inturn couples with the gas via feedback to drive turbulence. We find that the PS is almost non-existent if the disc potential is too strong or the ISM is highly structured on sub-kiloparsec scales. This can happen in the absence of stellar feedback when the gas is allowed to cool. In the presence of turbulent gas maintained by stellar feedback, the PS has a patchy spatial distribution and a high degree of intermittency on kiloparsec scales. We anticipate that future studies of the phase-spiral behaviour on all scales will provide crucial information on star-gas dynamics.
Zugangs-URL: https://doi.org/10.1093/mnras/staf1331
Datenbank: SwePub
Beschreibung
Abstract:The Gaia satellite revealed a remarkable spiral pattern (‘phase spiral’, PS) in the z–Vz phase–plane throughout the solar neighbourhood, where z and Vz are the displacement and velocity of a star perpendicular to the Galactic plane. As demonstrated by many groups, the kinematic signature reflects the Galactic stellar disc’s response to a dynamical disturbance some 0.3–3 Gyr ago. However, previous controlled simulations did not consider the impact of the multiphase interstellar medium (ISM) on the existence of the PS. This is crucial because it has been suggested that this weak signal is highly susceptible to scattering by small-scale density fluctuations typical of the ISM. This has motivated us to explore the formation and fate of the PS in a suite of high-resolution, N-body/hydrodynamical simulations of an idealized Galaxy analogue bearing a realistic ISM that interacts impulsively with a massive perturber. In our models, high-gas surface densities within the disc encourage vigorous star formation, which inturn couples with the gas via feedback to drive turbulence. We find that the PS is almost non-existent if the disc potential is too strong or the ISM is highly structured on sub-kiloparsec scales. This can happen in the absence of stellar feedback when the gas is allowed to cool. In the presence of turbulent gas maintained by stellar feedback, the PS has a patchy spatial distribution and a high degree of intermittency on kiloparsec scales. We anticipate that future studies of the phase-spiral behaviour on all scales will provide crucial information on star-gas dynamics.
ISSN:00358711
DOI:10.1093/mnras/staf1331