No Evolution in the Half-mass Radius of Milky Way-type Galaxies over the Last 10 Gyr

Abstract

The Milky Way (MW) galaxy is in focus, thanks to new observational data. Here we shed new light on the MW's past by studying the structural evolution of MW progenitors, which we identify from extragalactic surveys. Specifically, we constrain the stellar-mass growth history (SMGH) of the MW with two methods: ($i$) direct measurement of the MW's star formation history, and ($ii$) assuming the MW is a typical star-forming galaxy that remains on the star-forming main sequence. We select MW progenitors based on these two SMGHs at $z=0.2-2.0$ from the CANDELS/3D-HST data. We estimate the structural parameters (including half-mass radius $r_{50}$ and Sérsic index) from the stellar-mass profiles. Our key finding is that the progenitors of the MW galaxy grow self-similarly on spatially resolved scales with roughly a constant half-mass radius ($\sim 2-3$ kpc) over the past 10 Gyr, while their stellar masses increase by about 1 dex, implying little-to-no inside-out growth. We discover that the radius containing $20\%$ of the stellar mass ($r_{20}$) decreases by $60\%$ between redshifts of $z=2.0$ and $z=0.7$, while the central stellar-mass density (${\Sigma }_1$) increases by a factor of 1.3 dex over the same time and the Sérsic index changes as $n\propto (1+z{)}^{-1.41\pm 0.19}$. This is consistent with an early ($z>1$) formation of a thick disk, followed by the formation of a bar that led to an increase in the mass in the core. The formation and evolution of the thin disk had only little impact on the overall half-mass size. We also show that the constant-size evolution of the MW progenitors challenges semiempirical approaches and numerical simulations.

arXiv commentPublished in ApJL; 8 pages, 5 figures; doi:10.3847/2041-8213/ac76c8

References in corpus (51)

• Gaia Data Release 2. Summary of the contents and survey properties
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• Galactic star formation and accretion histories from matching galaxies to dark matter haloes
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The mass distribution and gravitational potential of the Milky Way
• Co-formation of the Galactic disc and the stellar halo
• First Results from the TNG50 Simulation: Galactic outflows driven by supernovae and black hole feedback
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• First Results from the TNG50 Simulation: The evolution of stellar and gaseous disks across cosmic time
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• Improved Estimates of the Milky Way's Stellar Mass and Star Formation Rate from Hierarchical Bayesian Meta-Analysis
• The formation and assembly history of the Milky Way revealed by its globular cluster population
• The Confinement of Star-Forming Galaxies into a Main Sequence through Episodes of Gas Compaction, Depletion, and Replenishment
• Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge
• Evidence for Mature Bulges and an Inside-out Quenching Phase 3 Billion Years After the Big Bang
• Newly-quenched galaxies as the cause for the apparent evolution in average size of the population
• A universal structural and star-forming relation since $z\sim 3$: connecting compact star-forming and quiescent galaxies
• The Assembly of Milky Way-like Galaxies Since z~2.5
• Kraken reveals itself -- the merger history of the Milky Way reconstructed with the E-MOSAICS simulations
• Where stars form: inside-out growth and coherent star formation from HST Halpha maps of 2676 galaxies across the main sequence at z~1
• The Galaxy-Halo Connection Over The Last 13.3 Gyrs
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• COSMOS-DASH: The Evolution of the Galaxy Size-Mass Relation Since z~3 from new Wide Field WFC3 Imaging Combined with CANDELS/3DHST
• Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances
• Fuel Efficient Galaxies: Sustaining Star Formation with Stellar Mass Loss
• Reconstructing the Last Major Merger of the Milky Way with the H3 Survey
• Mapping the Stellar Halo with the H3 Spectroscopic Survey
• Dust attenuation, bulge formation and inside-out cessation of star-formation in Star-Forming Main Sequence galaxies at z~2
• ZFOURGE/CANDELS: On the Evolution of M* Galaxy Progenitors from z=3 to 0.5
• Half-mass radii for ~7,000 galaxies at 1.0 < z < 2.5: most of the evolution in the mass-size relation is due to color gradients
• Using Cumulative Number Densities to Compare Galaxies across Cosmic Time
• z~2: An Epoch of Disk Assembly
• Timing the Early Assembly of the Milky Way with the H3 Survey
• The Inside-out Growth of the Galactic Disk
• Connection Between Stellar Mass Distributions Within Galaxies and Quenching Since z =2
• A Different Approach to Galaxy Evolution
• An analysis of the evolving comoving number density of galaxies in hydrodynamical simulations
• The SINS/zC-SINF Survey of z~2 Galaxy Kinematics: Rest-frame Morphology, Structure, and Colors from Near-infrared Hubble Space Telescope Imaging
• Half-mass radii of quiescent and star-forming galaxies evolve slowly from 0 < z < 2.5: implications for galaxy assembly histories
• Disk Growth and Quenching
• Return to [Log-]Normalcy: Rethinking Quenching, The Star Formation Main Sequence, and Perhaps Much More
• Phylogeny of the Milky Way's inner disk and bulge populations: Implications for gas accretion, (the lack of) inside-out thick disk formation, and quenching
• The Structural Evolution of Milky Way-like Star Forming Galaxies since z~1.3
• Galaxy Sizes Since $z=2$ from the Perspective of Stellar Mass Distribution within Galaxies
• A New View of the Size-Mass Distribution of Galaxies: Using $r_{20}$ and $r_{80}$ instead of $r_{50}$
• Spatial distribution of stellar mass and star formation activity at 0.2<z<1.2 across and along the Main Sequence
• The Zurich Environmental Study (ZENS) of Galaxies in Groups along the Cosmic Web. II. Galaxy Structural Measurements and the Concentration of Morphologically Classified Satellites in Diverse Environments
• On the Angular Momentum History of Galactic Disks
• The angular momentum of disc galaxies: implications for gas accretion, outflows, and dynamical friction
• The global and radial stellar mass assembly of Milky Way-sized galaxies

Cited by in corpus (2)

• The evolution of radial gradients of MaNGA quiescent elliptical galaxies: inside-out quenching or outer mass growth?
• Self-Similar Buildup and Inside-Out Growth: Tracing the Evolution of Intermediate to High-Mass Star-Forming Galaxies Since $z=2$