INSIDE OUT AND UPSIDE DOWN: TRACING THE ASSEMBLY OF A SIMULATED DISK GALAXY USING MONO-AGE STELLAR POPULATIONS

By J. Bird, S. Kazantzidis, D. Weinberg, J. Guedes, Simone Callegari, Lucio Mayer, P. Madau. 2013

163 citations recorded by the source corpus.

We analyze the present day structure and assembly history of a high-resolution hydrodynamic simulation of the formation of a Milky-Way-(MW)-like disk galaxy, from the “Eris” simulation suite, dissecting it into cohorts of stars formed at different epochs of cosmic history. At z = 0, stars with tform < 2 Gyr mainly occupy the stellar spheroid, with the oldest (earliest forming) stars having more centrally concentrated profiles. The younger age cohorts populate disks of progressively longer radial scale lengths and shorter vertical scale heights. At a given radius, the vertical density profiles and velocity dispersions of stars vary smoothly as a function of age, and the superposition of old, vertically extended and young, vertically compact cohorts gives rise to a double-exponential profile like that observed in the MW. Turning to formation history, we find that the trends of spatial structure and kinematics with stellar age are largely imprinted at birth, or immediately thereafter. Stars that form during the active merger phase at z > 3 are quickly scattered into rounded, kinematically hot configurations. The oldest disk cohorts form in structures that are radially compact and relatively thick, while subsequent cohorts form in progressively larger, thinner, colder configurations from gas with increasing levels of rotational support. The disk thus forms “inside out” in a radial sense and “upside down” in a vertical sense. Secular heating and radial migration influence the final state of each age cohort, but the changes they produce are small compared to the trends established at formation. The predicted correlations of stellar age with spatial and kinematic structure are in good qualitative agreement with the correlations observed for mono-abundance stellar populations in the MW.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d4fa501486ecc4f2c090c15c2ce697321fda4e56

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation (2017, background): “…are usually considered to be growing inside-out by continuous star-formation that is fed by accretion from outside the galaxy (Pichon et al. 2011; Bird et al. 2013), and indeed the effective sizes of the star-forming parts of disc galaxies are observed to be typically larger than the effective…”
Dissecting simulated disc galaxies - I. The structure of mono-age populations (2014, background): “In the light of these new observational results, numerical simulations have also been sliced into mono-abundance or mono-age populations (Bird et al. 2013; Stinson et al. 2013) and show interesting similarities with the structure of the Milky Way.”
THE RELATIONSHIP BETWEEN MONO-ABUNDANCE AND MONO-AGE STELLAR POPULATIONS IN THE MILKY WAY DISK (2016, result): “The general formation and evolutionary behavior of the disk formation is similar to many recent simulations in the cosmological context (e.g., Brook et al. 2012; Stinson et al. 2013; Bird et al. 2013; Marinacci et al. 2014).”
Chemodynamical evolution of the Milky Way disk - I. The solar vicinity (2012, result): “The high stellar birth velocity dispersions at high redshift we find in our simulation (∼50 km/s) is consistent with recent works (Forbes et al., 2012; Brook et al., 2012; Bird et al., 2013).”
Measuring Radial Orbit Migration in the Galactic Disk (2018, background): “…structure must at some level reflect both the global initial conditions, such as the total angular momentum and distribution of the cold gas, and the hierarchical merging during the early turbulent phases of the Milky Way’s formation (Brook et al. 2004; Bird et al. 2013; Stinson et al. 2013).”
Vertical disc heating in Milky Way-sized galaxies in a cosmological context (2015, background): “These results highlight that upside-down disc formation (Bird et al. 2013; Stinson et al. 2013b; Bovy et al. 2015) occurs on some level ubiquitously, which has important implications for thick disc formation.”
Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s) (2017, background): “Viable formation scenarios for the Milky Way disc include inside–out and upside–down formation (e.g. Matteucci & Francois 1989; Brook et al. 2006; Bird et al. 2013; Ness et al. 2016; Schönrich & McMillan 2017), although there are suggestions that the old component of the disc formed outside–in…”
The age structure of stellar populations in the solar vicinity Clues of a two-phase formation history of the Milky Way disk (2013, background): “The recent models by Bird et al. (2013) seem to support this scenario: their thick disk stars have small formation radii, and their guiding centers do not change significantly over time, thus indicating that thick disk stars had already eccentric orbits at the time of their formation.”
The age–metallicity structure of the Milky Way disc using APOGEE (2017, methodology): “Structurally, the mono-age populations of simulated galaxies show good agreement with the Milky Way (e.g. Stinson et al. 2013; Bird et al. 2013; Martig et al. 2014a,b).”
CHEMICAL CARTOGRAPHY WITH APOGEE: METALLICITY DISTRIBUTION FUNCTIONS AND THE CHEMICAL STRUCTURE OF THE MILKY WAY DISK (2015, methodology): “The fraction of stars that undergo radial migration is difficult to predict from first principles because it depends in detail on spiral structure, bar perturbations, and perturbations by and mergers with satellites (e.g., Roškar et al. 2008; Bird et al. 2012, 2013; Minchev et al. 2013).”
Chemodynamical evolution of the Milky Way disk II: Variations with Galactic radius and height above the disk plane (2014, result): “11) This is in agreement with recent results from simulations of spiral galaxies (e.g., Brook et al. 2012; Stinson et al. 2013; Bird et al. 2013) and observations in the MW (Bensby et al., 2011; Bovy et al., 2012b).”
Impacts of a flaring star-forming disc and stellar radial mixing on the vertical metallicity gradient (2016, background): “…disc population is flaring, although the radial mixing will reduce the strength of the flaring, and it is likely that earlier generations of the thin disc were smaller and thicker as seen in numerical simulations (Brook et al. 2004, 2006; Bird et al. 2013; Minchev et al. 2015; Grand et al. 2016).”
CHEMICAL CARTOGRAPHY WITH APOGEE: LARGE-SCALE MEAN METALLICITY MAPS OF THE MILKY WAY DISK (2013, background): “Many models predict that galaxies form inside-out, with star formation proceeding more rapidly, and perhaps starting earlier, in the inner regions of disks (e.g., Larson 1976; Kobayashi & Nakasato 2011; Bird et al. 2013).”
Numerical simulation of a possible origin of the positive radial metallicity gradient of the thick disk (2013, background): “Figure 4 shows a “flaring” feature (e.g. Bird et al. 2012, 2013; Roškar et al. 2013) for the younger stars.”
TRACING CHEMICAL EVOLUTION OVER THE EXTENT OF THE MILKY WAY'S DISK WITH APOGEE RED CLUMP STARS (2014, background): “…largely as it is seen today, from a hot interstellar medium at the onset of disk formation, as favored by recent cosmological simulations (e.g., Bird et al. 2013; Stinson et al. 2013) and observations of high-mass disk galaxies at z ≈ 2 (e.g., Förster Schreiber et al. 2011), or by a…”
Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient (2018, background): “1) and expected from a range of disk formation simulations (e.g., Roškar et al. 2008; Brook et al. 2012, Bird et al. 2013; Ma et al. 2017); • Resulting rbirth distribution of oldest mono-age bin peaks at ∼ 4 kpc - if this peak was located at a smaller radius, negative birth radii would result for…”
PLATO as it is: a legacy mission for Galactic archaeology (2017, unknown): “…thick and thin disks in disk galaxies as we see them now, was established, as suggested by many theoretical models (e.g., Abadi et al. 2003; Bird et al. 2013; Bournaud et al. 2009; Brook et al. 2004; Gibson et al. 2009; Guedes et al. 2013; Jones & Wyse 1983; Kawata & Chiappini 2016;…”