Vertical density waves in the Milky Way disc induced by the Sagittarius dwarf galaxy

Gómez, Facundo A.; Minchev, Ivan; O’Shea, Brian W.; Beers, Timothy C.; Bullock, James S.; Purcell, Chris W.

doi:10.1093/mnras/sts327

Cited by 236 publications

(291 citation statements)

References 27 publications

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“…The validity of this diagnostic was confirmed with N-body simulations (Gómez et al 2012b) and found to be consistent with structure in the SEGUE G-dwarf sample (Gómez et al 2012a). Gómez et al (2013) showed that just such a disturbance from the Sagittarius dwarf galaxy can explain the recent discovery of vertical waves near the Sun in SEGUE (Widrow et al 2012) and RAVE (Williams et al 2013). …”

Section: Constraining Recent Merger Eventsmentioning

confidence: 64%

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Constraining the Milky Way assembly history with Galactic Archaeology

Minchev

2016

Astron Nachr

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The aim of Galactic Archaeology is to recover the evolutionary history of the Milky Way from its present day kinematical and chemical state. Because stars move away from their birth sites, the current dynamical information alone is not sufficient for this task. The chemical composition of stellar atmospheres, on the other hand, is largely preserved over the stellar lifetime and, together with accurate ages, can be used to recover the birthplaces of stars currently found at the same Galactic radius. In addition to the availability of large stellar samples with accurate 6D kinematics and chemical abundance measurements, this requires detailed modeling with both dynamical and chemical evolution taken into account. An important first step is to understand the variety of dynamical processes that can take place in the Milky Way, including the perturbative effects of both internal (bar and spiral structure) and external (infalling satellites) agents. We discuss here (1) how to constrain the Galactic bar, spiral structure, and merging satellites by their effect on the local and global disc phase-space, (2) the effect of multiple patterns on the disc dynamics, and (3) the importance of radial migration and merger perturbations for the formation of the Galactic thick disc. Finally, we discuss the construction of Milky Way chemo-dynamical models and relate to observations.

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Section: Constraining Recent Merger Eventsmentioning

confidence: 64%

“…Evidence for merger encounters can be found in the phasespace structure of Milky Way disc stars (e.g., Gómez et al 2013Gómez et al , 2012bMinchev et al 2009). …”

Section: The Galactic Thick Discmentioning

confidence: 99%

Constraining the Milky Way assembly history with Galactic Archaeology

Minchev

2016

Astron Nachr

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“…Evidence for satellite-disk encounters can be found in structure in the phase-space of MW disk stars (e.g., Minchev et al 2009;Gómez et al 2013Gómez et al , 2012c, which can last for as long as ∼4 Gyr (Gómez et al 2012a). …”

Section: Thick-disk Formation Scenariosmentioning

confidence: 99%

Chemodynamical evolution of the Milky Way disk

Minchev

Chiappini

Martig

2013

A&A

442

574

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In the first paper of this series, we present a new approach for studying the chemo-dynamical evolution in disk galaxies, which consists of fusing disk chemical evolution models with compatible numerical simulations of galactic disks. This method avoids known star formation and chemical enrichment problems encountered in simulations. Here we focus on the Milky Way, by using a detailed thindisk chemical evolution model (matching local observables, which are weakly affected by radial migration) and a simulation in the cosmological context, with dynamical properties close to those of our Galaxy. We examine in detail the interplay between in situ chemical enrichment and radial migration and their impact on key observables in the solar neighborhood, e.g., the age-metallicityvelocity relation, the metallicity distribution, and gradients in the radial and vertical directions. We show that, due to radial migration from mergers at high redshift and the central bar at later times, a sizable fraction of old metal-poor high-[α/Fe] stars can reach the solar vicinity. This naturally accounts for a number of recent observations related to both the thin and thick disks, despite the fact that we use thin-disk chemistry only. Although significant radial mixing is present, the slope in the age-metallicity relation is only weakly affected, with a scatter compatible with recent observational work. While we find a smooth density distribution in the [O/Fe]-[Fe/H] plane, we can recover the observed discontinuity by selecting particles according to kinematic criteria used in high-resolution samples to define the thin and thick disks. We outline a new method for estimating the birth place of the Sun and predict that the most likely radius lies in the range 4.4 < r < 7.7 kpc (for a current location at r = 8 kpc). A new, unifying model for the Milky Way thick disk is offered, where both mergers and radial migration play a role at different stages of the disk evolution. We show that in the absence of early-on massive mergers the vertical velocity dispersion of the oldest stars is underestimated by a factor of ∼2 compared with observations. We can, therefore, argue that the Milky Way thick disk is unlikely to have been formed through a quiescent disk evolution. An observational test involving both chemical and kinematic information must be devised to ascertain this possibility.

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“…Velocity and number density perturbations normal to the Galactic midplane can result from satellite-disk interactions (Widrow et al 2012;Gómez et al 2013;Widrow et al 2014). Gómez et al (2013), for example, used N-body experiments to show that a Sagittarius-like dwarf with a mass of 10 10.5 − 10 11 M⊙ could produce density perturbations of the same amplitude as was seen in Widrow et al (2012) and Yanny & Gardner (2013).…”

Section: Introductionmentioning

confidence: 99%

Vertical oscillations of fluid and stellar discs

Widrow

Bonner

2015

Monthly Notices of the Royal Astronomical Society

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A satellite galaxy or dark matter subhalo that passes through a stellar disk may excite coherent oscillations in the disk perpendicular to its plane. We determine the properties of these modes for various self-gravitating plane symmetric systems (Spitzer sheets) using the matrix method of Kalnajs. In particular, we find an infinite series of modes for the case of a barotropic fluid. In general, for a collisionless system, there is a double series of modes, which include normal modes and/or Landau-damped oscillations depending on the phase space distribution function of the stars. Even Landau-damped oscillations may decay slowly enough to persist for several hundred Myr. We discuss the implications of these results for the recently discovered vertical perturbations in the kinematics of solar neighborhood stars and for broader questions surrounding secular phenomena such as spiral structure in disk galaxies.

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Vertical density waves in the Milky Way disc induced by the Sagittarius dwarf galaxy

Cited by 236 publications

References 27 publications

Constraining the Milky Way assembly history with Galactic Archaeology

Constraining the Milky Way assembly history with Galactic Archaeology

Chemodynamical evolution of the Milky Way disk

Vertical oscillations of fluid and stellar discs

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