Keeping It Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk

Frankel, Neige; Sanders, Jason L.; Ting, Yuan-Sen; Rix, Hans─Walter

doi:10.3847/1538-4357/ab910c

Cited by 91 publications

(98 citation statements)

References 110 publications

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“…Galactic evolution models often simplify the abundance distributions of gas in galaxies to a 1-D model (e.g. Minchev et al 2018;Mollá et al 2019a;Frankel et al 2020), with azimuthal scatter assumed from measurements at z = 0. While this is a useful first step in understanding the abundance evolution of galaxies and testing chemical tagging, our results mean that this simplifying assumption overestimates the radial information content in elemental abundances, including how well chemical tagging can constrain the birth radius of a star.…”

Section: Discussionmentioning

confidence: 99%

“…We thus test a common assumption in galactic evolution, that gas is well mixed azimuthally within a given annulus (e.g. Frankel et al 2018;Frankel et al 2020). Fig.…”

Section: Azimuthal Variations Across Timementioning

confidence: 99%

“…Consequently, works modeling the abundance evolution of galaxies, which inform chemical tagging, generally assume that gas is well mixed azimuthally in the disk at all times (e.g. Minchev et al 2018;Mollá et al 2019a;Frankel et al 2020), such that the key spatial variation is radial. While galaxies exhibit radial gradients across a range of redshifts (Queyrel et al 2012;Stott et al 2014;Wuyts et al 2016;Carton et al 2018;Patrício et al 2019;Curti et al 2020), radial variations may not always dominate.…”

Section: Introductionmentioning

confidence: 99%

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3D gas-phase elemental abundances across the formation histories of Milky Way-mass galaxies in the FIRE simulations: initial conditions for chemical tagging

Bellardini

Wetzel

Loebman

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We use FIRE-2 simulations to examine 3-D variations of gas-phase elemental abundances of [O/H], [Fe/H], and [N/H] in 11 MW and M31-mass galaxies across their formation histories at z ≤ 1.5 ($t_{\rm lookback} \le 9.4 \, \rm {Gyr}$), motivated by characterizing the initial conditions of stars for chemical tagging. Gas within $1 \, \rm {kpc}$ of the disk midplane is vertically homogeneous to $\lesssim 0.008 \, \rm {dex}$ at all z ≤ 1.5. We find negative radial gradients (metallicity decreases with galactocentric radius) at all times, which steepen over time from $\approx -0.01 \, \rm {dex}\, \rm {kpc}^{-1}$ at z = 1 ($t_{\rm lookback} = 7.8 \, \rm {Gyr}$) to $\approx -0.03 \, \rm {dex}\, \rm {kpc}^{-1}$ at z = 0, and which broadly agree with observations of the MW, M31, and nearby MW/M31-mass galaxies. Azimuthal variations at fixed radius are typically $0.14 \, \rm {dex}$ at z = 1, reducing to $0.05 \, \rm {dex}$ at z = 0. Thus, over time radial gradients become steeper while azimuthal variations become weaker (more homogeneous). As a result, azimuthal variations were larger than radial variations at z ≳ 0.8 ($t_{\rm lookback} \gtrsim 6.9 \, \rm {Gyr}$). Furthermore, elemental abundances are measurably homogeneous (to ≲ 0.05 dex) across a radial range of $\Delta R \approx 3.5 \, \rm {kpc}$ at z ≳ 1 and $\Delta R \approx 1.7 \, \rm {kpc}$ at z = 0. We also measure full distributions of elemental abundances, finding typically negatively skewed normal distributions at z ≳ 1 that evolve to typically Gaussian distributions by z = 0. Our results on gas abundances inform the initial conditions for stars, including the spatial and temporal scales for applying chemical tagging to understand stellar birth in the MW.

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Section: Discussionmentioning

confidence: 99%

“…We thus test a common assumption in galactic evolution, that gas is well mixed azimuthally within a given annulus (e.g. Frankel et al 2018;Frankel et al 2020). Fig.…”

Section: Azimuthal Variations Across Timementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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3D gas-phase elemental abundances across the formation histories of Milky Way-mass galaxies in the FIRE simulations: initial conditions for chemical tagging

Bellardini

Wetzel

Loebman

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…Therefore, our interpretations come from basic principles and consider the star formation happening homogeneously through the entire thin and thick disk. This is of course an over simplication of reality -there is enough evidence pointing towards an inside-out formation of the disk (Frankel et al 2018(Frankel et al , 2020Buck 2020) producing a dependency of star formation eciency (hence chemical enrichment rate) as a function of Galactic radius. This is reected in signicant metallicity gradients across the disk (Magrini et al 2017).…”

Section: Reconstruction Of the Galaxy History In Context Of Radial MImentioning

confidence: 99%

Using heritability of stellar chemistry to reveal the history of the Milky Way

Jackson

Jofré

Yaxley

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Since chemical abundances are inherited between generations of stars, we use them to trace the evolutionary history of our Galaxy. We present a robust methodology for creating a phylogenetic tree, a biological tool used for centuries to study heritability. Combining our phylogeny with information on stellar ages and dynamical properties, we reconstruct the shared history of 78 stars in the solar neighbourhood. The branching pattern in our tree supports a scenario in which the thick disc is an ancestral population of the thin disc. The transition from thick to thin disc shows an anomaly, which we attribute to a star formation burst. Our tree shows a further signature of the variability in stars similar to the Sun, perhaps linked to a minor star formation enhancement creating our Solar system. In this paper, we demonstrate the immense potential of a phylogenetic perspective and interdisciplinary collaboration, where with borrowed techniques from biology we can study key processes that have contributed to the evolution of the Milky Way.

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“…It would have been interesting to compare the results obtained with real data, notably those concerning the Milky Way obtained by Gaia-RVS (Trick et al 2019), or recent models also expressed in the action-angle domain (e.g. Frankel et al 2020, and reference therein). However, as mentioned several times, RunC does not have the characteristics of the Milky Way.…”

Section: Discussionmentioning

confidence: 99%

Diffusion of radial action in a galactic disc

Wozniak¹

2020

A&A

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Context. The stellar migration of the galactic disc stars has been invoked to explain the dispersion of stellar metallicity observed in the solar neighbourhood. Aims. We seek to identify the dynamical mechanisms underlying stellar migration in an isolated galaxy disc under the influence of a bar. Our approach is to analyse the diffusion of dynamical quantities. Methods. We extend our previous work by exploring Chirikov’s diffusion rate (and derived timescale) of the radial action JR in an idealised N-body simulation of an isolated disc galaxy. We limit our study to the evolution of the disc region well after the formation of the bar, in a regime of adiabatic evolution. Results. The JR diffusion timescale TD(JR) is less than 3 Gyr for roughly half the galaxy mass. It is always much shorter than the angular momentum diffusion timescale TD(Lz) outside the stellar bar. In the disc, ⟨TD(JR)⟩ ∼ 1 Gyr. All non-axisymmetric morphological structures that are characteristic of resonances and waves in the disc are associated to particles with TD(JR) < 3 Gyr and TD(Lz) > 10 Gyr. Short TD(JR) can be explained by the gradual de-circularisation of initially circular orbits (JR = 0) under the effect of intermittent. Inner Linblad resonance scattering by wave trains propagating in the disc, well beyond the outer Lindblad resonance of the bar (OLR). This leads to a moderate secular heating of the disc beyond the bar’s OLR for 7 Gyr, which is comparable to solar neighbourhood observations. The complex multi-wave structure, mixing permanent and intermittent modes, allows for multiple resonance overlaps.

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Keeping It Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk

Cited by 91 publications

References 110 publications

3D gas-phase elemental abundances across the formation histories of Milky Way-mass galaxies in the FIRE simulations: initial conditions for chemical tagging

3D gas-phase elemental abundances across the formation histories of Milky Way-mass galaxies in the FIRE simulations: initial conditions for chemical tagging

Using heritability of stellar chemistry to reveal the history of the Milky Way

Diffusion of radial action in a galactic disc

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