Migration and heating in the galactic disc from encounters between Sagittarius and the Milky Way

Carr, Christopher; Johnston, Kathryn V.; Laporte, Chervin F. P.; Ness, Melissa

doi:10.1093/mnras/stac2403

Cited by 15 publications

(5 citation statements)

References 71 publications

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“…6). Carr et al (2022) also showed the impact of a massive satellite in the outer disc, where the radial migration strength increases with radius and the guiding radius increases by more than 1 kpc explicitly whereR gal > 8 kpc (see their Fig. 9).…”

Section: Sf Enhancement As a Function Of R Galmentioning

confidence: 86%

Impact of orbiting satellites on star formation rate evolution and metallicity variations in Milky Way-like discs

Annem¹,

Khoperskov²

2022

Preprint

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At least one major merger is currently taking place in the Milky Way (MW). The Sgr dwarf spheroidal galaxy is being tidally destroyed while orbiting around the MW, whose close passages perturb the MW disc externally. In this work, using a series of hydrodynamical simulations, we investigate how massive dwarf galaxies on quasi-polar Sgr-like orbits impact the star formation activity inside the MW-like discs. First, we confirm that interactions with orbiting satellites enhance the star formation rate in the host galaxy. However, prominent short-time scale bursts are detected during the very close passages (< 20 kpc) of massive (> 2 × 10 10 M ) gas-poor satellites. In the case of gas-rich satellites, while we see a substantial enhancement of the star formation on a longer time scale, we do not detect prominent peaks in the star formation history of the host. This can be explained by the steady accretion of gas being stripped from the satellite, which smoothens short-term variations in the star formation rate of the host. It is important that the impact of the satellite perturbations, especially its first encounters, is seen mainly in the outer (> 10 kpc) disc of the host. We also found that the close passages of satellites cause the formation of a substantial amount of low-metallicity stars in the host, and the effect is the most prominent in the case of gas infall from the satellites resulting in the dilution of the mean stellar metallicity soon after the first pericentric passage of massive satellites. Our simulations are in favour of causality between the recent passages of the Sgr galaxy and the bursts of the star formation (SF) in the solar neighbourhood (≈ 1 and ≈ 2 Gyr ago); however, in order to reproduce the SF burst at its first infall (≈ 6 Gyr), we require a very close pericentric passage (< 20 kpc) with subsequent substantial mass loss of the Sgr precursor.

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Section: Sf Enhancement As a Function Of R Galmentioning

confidence: 86%

Impact of orbiting satellites on star formation rate evolution and metallicity variations in Milky Way-like discs

Annem¹,

Khoperskov²

2022

Preprint

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“…The disruption of Sgr is contributing to the build-up of the MW halo in terms of dark matter, stars, and globular clusters (see, e.g., Majewski et al 2003;Huxor & Grebel 2015;Hasselquist et al 2019;Bellazzini et al 2020). The interaction with the MW appears to have left its imprint in the structure, kinematics and star formation history of the MW disc (see, e.g., Laporte et al 2019;Ruiz-Lara et al 2020;Carr et al 2022). Vasiliev & Belokurov (2020) estimates that the present-day total mass of the main body is M ∼ 4 × 10 8 M , with M ∼ 1 × 10 8 M in stars, but several lines of evidence suggest that the original progenitor of the system was significantly more massive, in the range 10 10 −10 11 M (Łokas et al 2010;Niederste-Ostholt Based on observations collected at the ESO-VLT under programs 105.20AH.001 Gibbons et al 2017;Dierickx & Loeb 2017;Minelli et al 2021;Vasiliev et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…The interaction with the MW appears to have left its imprint on the structure, kinematics, and star formation history of the MW disc (see e.g. Laporte et al 2019;Ruiz-Lara et al 2020;Carr et al 2022). Vasiliev & Belokurov (2020) estimates that the present-day total mass of the main body is M ∼ 4 × 10 8 M ⊙ , with M ⋆ ∼ ⋆ Based on observations collected at the ESO-VLT under programs 105.20AH.001 ⋆⋆ Full Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/cgi-bin/qcat?J/A+A/2022/44890 1 × 10 8 M ⊙ in stars, but several lines of evidence suggest that the original progenitor of the system was significantly more massive, in the range 10 10 −10 11 M ⊙ (Łokas et al 2010;Niederste-Ostholt et al 2012;Gibbons et al 2017;Dierickx & Loeb 2017;Minelli et al 2021;Vasiliev et al 2021).…”

Section: Introductionmentioning

confidence: 99%

The metallicity distribution in the core of the Sagittarius dwarf spheroidal: Minimising the metallicity biases

Minelli

Bellazzini²,

Mucciarelli

et al. 2023

A&A

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We present metallicity and radial velocity for 450 bona-fide members of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy, measured from high resolution (R 18000) FLAMES@VLT spectra. The targets were carefully selected (a) to sample the core of the main body of Sgr dSph while avoiding contamination from the central stellar nucleus, and (b) to prevent any bias on the metallicity distribution, by selecting targets based on their Gaia parallax and proper motions. All the targets selected in this way were confirmed as radial velocity members. We used this sample to derive the first metallicity distribution of the core of the Sgr dSph virtually unaffected by metallicity biases. The observed distribution ranges from [Fe/H] −2.3 to [Fe/H] 0.0, with a strong, symmetric and relatively narrow peak around [Fe/H] −0.5 and a weak, extended metal-poor tail, with only 13.8 ± 1.9% of the stars having [Fe/H]< −1.0. We confirm previous evidence of correlations between chemical and kinematical properties of stars in the core of Sgr. In our sample stars with [Fe/H]≥ −0.6 display a lower velocity dispersion and a higher rotation amplitude than those with [Fe/H]< −0.6, confirming previous suggestions of a disk/halo structure for the progenitor of the system.

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“…In addition, the effects of the galaxydwelling environment should also be accounted for. The presence of satellites and minor mergers predominantly affect the orbits of stars in the outskirts directly (Bird, Kazantzidis, & Weinberg, 2012;Carr et al, 2022). They also cause perturbations that lead to the formation of non-axisymmetric features and drive radial migrations and mixing indirectly.…”

Section: On the Concept Of A Ghzmentioning

confidence: 99%

Dynamical aspects of Galactic habitability in N-body simulations

Mitrašinović,

Vukotić,

Micic

et al. 2023

Publ. Astron. Soc. Aust.

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Recent studies of Galactic evolution revealed that the dynamics of the stellar component might be one of the key factors when considering galactic habitability. We run an N-body simulation model of the Milky Way, which we evolve for 10 Gyr, to study the secular evolution of stellar orbits and the resulting galactic habitability related properties, i.e., the density of the stellar component and close stellar encounters. The results indicate that radial migrations are not negligible, even in a simple axisymmetric model with mild levels of dynamical heating, and that the net outward diffusion of the stellar component can populate galactic outskirts with habitable systems. Habitable environment is also likely even at sub-Solar galactocentric radii, because the rate of close encounters should not significantly degrade habitability. Stars that evolve from non-circular to stable nearly circular orbits typically migrate outwards, settling down in a broad Solar neighbourhood. The region between $R \approx 3$ kpc and $R \approx 12$ kpc represents the zone of radial mixing, which can blur the boundaries of the Galactic Habitable Zone (GHZ), as it has been conventionally understood. The present-day stable population of the stars in the Solar neighbourhood originates from this radial mixing zone, with most of the stars coming from the inner regions. The Solar system can be considered as a typical Milky Way habitable system because it migrated outwards from the metal-rich inner regions of the Disk and has a circular orbit in the present epoch. We conclude that the boundaries of the GHZ cannot be sharply confined for a given epoch because of the mixing caused by the stellar migrations and secular evolution of stellar orbits.

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Migration and heating in the galactic disc from encounters between Sagittarius and the Milky Way

Cited by 15 publications

References 71 publications

Impact of orbiting satellites on star formation rate evolution and metallicity variations in Milky Way-like discs

Impact of orbiting satellites on star formation rate evolution and metallicity variations in Milky Way-like discs

The metallicity distribution in the core of the Sagittarius dwarf spheroidal: Minimising the metallicity biases

Dynamical aspects of Galactic habitability in N-body simulations

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