A NEW MECHANISM FOR RADIAL MIGRATION IN GALACTIC DISKS: SPIRAL–BAR RESONANCE OVERLAP

By I. Minchev, B. Famaey. 2009

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While it has long been known that a large number of short-lived transient spirals can cause stellar migration, here we report that another mechanism is also effective at mixing disks of barred galaxies. The resonance overlap of the bar and spiral structure (SS) induces a nonlinear response leading to a strong redistribution of angular momentum in the disk. We find that, depending on the amplitudes of the perturbers, the changes in angular momentum, ΔL, could occur up to an order of magnitude faster than in the case of recurrent spirals. The signature of this mechanism is a bimodality in ΔL with maxima near the bar's corotation and its outer Lindblad resonance; this is independent of the properties of the SS. For parameters consistent with the Milky Way, the disk mixes in about 3 Gyr and the stellar velocity dispersion increases with time in a manner roughly consistent with observations. This new mechanism could account for both the observed age–velocity relation and the absence of age–metallicity relation in the solar neighborhood. Spiral–bar interaction could also explain observations showing that strongly barred galaxies have weaker metallicity gradients than weakly barred or non-barred galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/096e40336df683b91ad5ff7285a8768eeedc3fc5

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Citations in the corpus

The age structure of stellar populations in the solar vicinity Clues of a two-phase formation history of the Milky Way disk (2013, background): “…migration, as it has been discussed in the literature A109, page 14 of 18 (Sellwood & Binney 2002; Schönrich & Binney 2009a; Roškar et al. 2008; Minchev & Famaey 2010; Minchev et al. 2011, 2012a,b; Di Matteo et al. 2013) is the result of a secular process related to the presence of stellar…”
Vertical disc heating in Milky Way-sized galaxies in a cosmological context (2015, background): “…a jump in velocity dispersion ∼ 8− 9 Gyr ago (Soubiran et al. 2008). mechanisms for radial migration, such as migration induced by spiral-bar coupling (Minchev & Famaey 2010), wave mode coupling (Comparetta & Quillen 2012), co-rotating spiral arms (Grand et al. 2012a,b, 2014; Kawata et al. 2014;…”
The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location (2018, background): “One mechanism that does not rely on transience was proposed by Minchev & Famaey (2010) and Minchev et al. (2011): this quasi-chaotic, unruly process results from interference between resonances from multiple rotating patterns, e.g. the central bar and the spiral arms which are known to rotate with…”
EVOLVING GRAVITATIONALLY UNSTABLE DISKS OVER COSMIC TIME: IMPLICATIONS FOR THICK DISK FORMATION (2011, background): “There are additional scattering mechanisms, such as two-body scattering and the resonant overlap between spirals and the bar (Minchev & Famaey 2010; Brunetti et al. 2011), which will also redistribute stellar angular momenta.”
THE VERTICAL METALLICITY GRADIENT OF THE MILKY WAY DISK: TRANSITIONS IN [α/Fe] POPULATIONS (2014, background): “…involves stars moving radially from the inner to – 5 – the outer regions of the disk, and vice versa, due to scattering by transient spiral structure (Sellwood & Binney 2002) or diffusion caused by overlap of bar-spiral resonances (Minchev & Famaey 2010; Brunetti et al. 2011; Minchev et al. 2011).”
A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA (2013, background): “Resonance patterns between the bar and the spiral pattern speed can shift the orbits of stars, mostly toward the outer regions (Minchev & Famaey 2010), a mechanism that also affects the gas.”
LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan (2012, background): “…& Wyse 1983; Brook et al. 2004); and 4) in-situ formation of the thick disk through radial migration of stars as a consequence of corotation resonance with transient spiral structures (Sellwood & Binney 2002), bar structures (Minchev & Famaey 2010), or orbiting satellites (Quillen et al. 2009).”
Constraints on Radial Migration in Spiral Galaxies - II. Angular momentum distribution and preferential migration (2018, background): “A complication we have not addressed in this work is the consequence of overlapping resonances from multiple patterns (e.g. Minchev & Famaey 2010) or multiple transient modes (Sellwood & Carlberg 2014).”
New constraints on the chemical evolution of the solar neighbourhood and galactic disc(s) - improved astrophysical parameters for the Geneva-Copenhagen Survey (2011, background): “The presence of a bar would rather imply the existence of an old metal-rich population, which we do not detect (but see Minchev & Famaey 2010; Minchev et al. 2011, for a recent dis- cussion on the effect of the bar).”
The Milky Way’s stellar disk (2013, background): “A similar—and potentially more efficient—process was later shown to happen when the bar and spiral structure’s resonances overlap (Minchev & Famaey 2010; Minchev et al. 2011).”
Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient (2018, background): “…(2006) identified a new galactic disk heating mechanism, resulting from the interaction among long-lived spiral modes moving at different pattern speeds and suggested that this also creates radial mixing, a phenomenon explored later in detail by Minchev & Famaey (2010) and Minchev et al. (2012a).”
Radial migration in galactic disks caused by resonance overlap of multiple patterns: Self-consistent simulations (2010, background): “Moreover, we have recently demonstrated (Minchev & Famaey 2010, hereafter MF10) that a strong exchange of angular momentum occurs when a stellar disk is perturbed by a central bar and SS simultaneously: our test-particle simulations allowed us to attribute thiseffect to the overlap or first and…”
THE STELLAR POPULATION STRUCTURE OF THE GALACTIC DISK (2015, background): “…(e.g., Quinn et al. 1993; Abadi et al. 2003; Brook et al. 2004) or through radial migration (e.g., Sellwood & Binney 2002; Schönrich & Binney 2009; Minchev & Famaey 2010; Loebman et al. 2011), the possibility that (at least some part of) the stellar disk formed “upside-down” with its current…”
The structure of the Milky Way's bar outside the bulge (2015, background): “It influences for example the disk outside the bar (Minchev & Famaey 2010), the kinematics in the solar neighbourhood (Dehnen 2000), and the observed non-circular gas flow (Bissantz et al. 2003).”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “In reality, these “components” exhibit strong overlap by virtue of sharing the same evolving Galactic potential (e.g., Guedes et al. 2013) and the likelihood that stars migrate far from their formation sites (Sellwood & Binney 2002, Minchev & Famaey 2010).”
FORMATION AND EVOLUTION OF THE DISK SYSTEM OF THE MILKY WAY: [α/Fe] RATIOS AND KINEMATICS OF THE SEGUE G-DWARF SAMPLE (2011, methodology): “…Rotational Velocity and Metallicity According to the radial migration models (Sellwood & Binney 2002; Roškar et al. 2008a; Schönrich & Binney 2009a; Minchev & Famaey 2010), the (presumably) metal-poor stars of the thin disk (which includes young, low-[α/Fe] stars) that were born in the outer disk…”
The Lives of Stars: Insights from the TGAS–RAVE–LAMOST Data Set (2018, background): “Minchev & Famaey (2010) expanded on this with the addition of a bar component and found that bars may affect angular momentum change in the vicinity of the corotation radius and the outer Lindblad resonance and also that bars may enhance the rate at which metallicity gradients flatten (Minchev et…”