Measuring Radial Orbit Migration in the Galactic Disk

Frankel, Neige; Rix, Hans─Walter; Ting, Yuan-Sen; Ness, Melissa; Hogg, David W.

doi:10.3847/1538-4357/aadba5

Cited by 159 publications

(224 citation statements)

References 78 publications

Supporting

Mentioning

202

Contrasting

Order By: Relevance

“…3 are selected to only show stars in between 7 < R < 9 kpc but we find that the highα sequence stars must have migrated outwards in order to be found at ∼ 8 kpc today while for the low-α sequence we find that stars come both from the inner and the outer disk (sometimes as far as 15 − 20 kpc). These results are in agreement with estimates of the radial migration strength of the MW disk stars (∼ 3.6 kpc Frankel et al 2018) and recent findings of a strong impact of radial migration in the MW by Feuillet et al (2019). We find that the α-bimodality is already present at time of birth of the stars but with a much stronger radial separation.…”

Section: Birth Radiisupporting

confidence: 93%

On the origin of the chemical bimodality of disc stars: a tale of merger and migration

Buck

2019

Monthly Notices of the Royal Astronomical Society

149

132

View full text Add to dashboard Cite

The Milky Way's stellar disk exhibits a bimodality in the [Fe/H] vs. [α/Fe] plane, showing a distinct high-α and low-α sequence whose origin is still under debate. We examine the [Fe/H]-[α/Fe] abundance plane in cosmological hydrodynamical simulations of Milky Way like galaxies from the NIHAO-UHD project and show that the bimodal α-sequence is a generic consequence of a gas-rich merger at some time in the Galaxy's evolution. The high-α sequence evolves first in the early galaxies, extending to high metallicities, while it is the low-α sequence that is formed after the gas-rich merger. The merger brings in fresh metal-poor gas diluting the interstellar medium's metallicity while keeping the [α/Fe] abundance almost unchanged. The kinematic, structural and spatial properties of the bimodal α-sequence in our simulations reproduces that of observations. In all simulations, the high-α disk is old, radially concentrated towards the galaxy's center and shows large scale heights. In contrast, the low-α disk is younger, more radially extended and concentrated to the disk mid-plane. Our results show that the abundance plane is well described by these two populations that have been distributed radially across the disk by migration: at present-day in the solar neighbourhood, low-α stars originate from both the inner and outer disk while high-α stars have all migrated from the inner disk. We show that age dating the stars in the [Fe/H]-[α/Fe] plane can constrain the time of the low-α sequence forming merger and conclude that α-bimodality is likely a not uncommon feature of disk galaxies.

show abstract

Section: Birth Radiisupporting

confidence: 93%

On the origin of the chemical bimodality of disc stars: a tale of merger and migration

Buck

2019

Monthly Notices of the Royal Astronomical Society

149

132

View full text Add to dashboard Cite

show abstract

“…This suggests that the radial migration of stars in the disc could be a significant process (e.g. Minchev et al 2014;Frankel et al 2018;Weinberg et al 2019). In this larger sample, there is also a secondary turnover feature around [M/H] ∼ 0.4 dex.…”

Section: Metallicity-age Relationmentioning

confidence: 79%

Spatial variations in the Milky Way disc metallicity–age relation

Feuillet

Frankel

Lind

et al. 2019

Monthly Notices of the Royal Astronomical Society

Self Cite

104

View full text Add to dashboard Cite

Stellar ages are a crucial component to studying the evolution of the Milky Way. Using Gaia DR2 distance estimates, it is now possible to estimate stellar ages for a larger volume of evolved stars through isochrone matching. This work presents [M/H]age and [α/M]-age relations derived for different spatial locations in the Milky Way disc. These relations are derived by hierarchically modelling the star formation history of stars within a given chemical abundance bin. For the first time, we directly observe that significant variation is apparent in the [M/H]-age relation as a function of both Galactocentric radius and distance from the disc mid-plane. The [M/H]-age relations support claims that radial migration has a significant effect in the plane of the disc. Using the [M/H] bin with the youngest mean age at each radial zone in the plane of the disc, the present-day metallicity gradient is measured to be −0.059 ± 0.010 dex kpc −1 , in agreement with Cepheids and young field stars. We find a vertically flared distribution of young stars in the outer disc, confirming predictions of models and previous observations. The mean age of the [M/H]-[α/M] distribution of the solar neighborhood suggests that the high-[M/H] stars are not an evolutionary extension of the low-α sequence. Our observational results are important constraints to Galactic simulations and models of chemical evolution.

show abstract

“…Strong secular evolution of the MW's stellar disk implies that detailed models have to be assumed in order to draw conclusions about the formation of the stellar disk from these surveys (for recent models of radial migration in the MW see e.g. Frankel et al 2018;Minchev et al 2018;Feltzing et al 2019). However, a detailed, observationally motivated study is outside the scope of this paper and will be left for future work.…”

Section: Time Evolution Of the Scale Length And Heightmentioning

confidence: 99%

NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations

Buck

Obreja

Macciò

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Simulating thin and extended galactic disks has long been a challenge in computational astrophysics. We introduce the NIHAO-UHD suite of cosmological hydrodynamical simulations of Milky Way mass galaxies and study stellar disk properties such as stellar mass, size and rotation velocity which agree well with observations of the Milky Way and local galaxies. In particular, the simulations reproduce the age-velocity dispersion relation and a multi-component stellar disk as observed for the Milky Way. Half of our galaxies show a double exponential vertical profile, while the others are well described by a single exponential model which we link to the disk merger history. In all cases, mono-age populations follow a single exponential whose scale height varies monotonically with stellar age and radius. The scale length decreases with stellar age while the scale height increases. The general structure of the stellar disks is already set at time of birth as a result of the inside-out and upside-down formation. Subsequent evolution modifies this structure by increasing both the scale length and height of all mono-age populations. Thus, our results put tight constraints on how much dynamical memory stellar disks can retain over cosmological timescales. Our simulations demonstrate that it is possible to form thin galactic disks in cosmological simulations provided there are no significant stellar mergers at low redshifts. Most of the stellar mass is formed in-situ with only a few percent ( ∼ < 5%) brought in by merging satellites at early times. Redshift zero snapshots and halo catalogues are publicly available.

show abstract

Measuring Radial Orbit Migration in the Galactic Disk

Cited by 159 publications

References 78 publications

On the origin of the chemical bimodality of disc stars: a tale of merger and migration

On the origin of the chemical bimodality of disc stars: a tale of merger and migration

Spatial variations in the Milky Way disc metallicity–age relation

NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations

Contact Info

Product

Resources

About