Séminaire/Seminar Galaxies |
| « A story of streams: the dynamical friction effect on the tails of globular clusters » |
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Aikaterini Niovi Triantafyllaki |
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Globular clusters travel within a galaxy, leaving behind a trail of stars in their orbits. The motions of the stream stars are governed by the potential they are in. The evaporation of these stars results in two tidal arms: the leading and the trailing. While these arms are populated symmetrically in the first approximation, Gaia data and subsequent research reveal asymmetries in the evaporation of open clusters (e.g., Pflamm-Altenburg et al., 2023). Hence, differences between the arms. We hypothesize that these asymmetries and inhomogeneities are caused by the wake of dynamical friction, primarily located on one side of the stream, thus influencing one arm more. We test this scenario by calculating the dynamical friction wake effects on the orbit of a globular cluster. We apply the method introduced by Kipper et al. (2023)to integrate the stars in the vicinity of the globular cluster into the past and then back to the present without the potential of the globular cluster. To our knowledge, the studies on the gas distribution specifics so far is limited and our research focuses on the local gas time-dependent inhomogeneities, such as how multiple supernovae explosions affect the gravitational potential of the galaxy's disk and hence the shape of a stellar stream that travels through, it as studied in Kipper et al, (2024)
We observe a strong dependence on the stream's location: a dark matter halo environment does not induce significant asymmetries, while disc contributions are more pronounced. With every passage through the disc, the wake forms and slightly changes the velocity of the stream stars while the formation of the biggest superbubbles, when it cohabits the same place with a stream, can produce gaps up to of 50% underdensity on the amount of gas that is pushed away from their origin and are capable of producing strong local changes in the gravitational potential to alter the passing stream. |
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jeudi 28 novembre 2024 - 11:30 Salle Entresol Daniel Chalonge Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |