The Physical Origin of the Mass-Size Relation and Its Scatter of Disk Galaxies

Abstract

Utilizing a kinematic decomposition of simulated galaxies, we focus on galaxies with tiny kinematically inferred stellar halos, indicative of weak external influences. We investigate the intricate interplay between internal (natural) and external (nurture) processes in shaping the scaling relationships of specific angular momentum ($j_{\star }$), stellar mass ($M_{\star }$), and size of disk galaxies within the IllustrisTNG simulation. The correlation among mass, size, and angular momentum of galaxies is examined by comparing simulations with observations and the theoretical predictions of the exponential hypothesis. Galaxies with tiny stellar halos exhibit a large scatter in the $j_{\star }$-$M_{\star }$ relation, which suggests that it is inherently present in their initial conditions. The analysis reveals that the disks of these galaxies adhere to the exponential hypothesis, resulting in a tight fiducial $j_{\star }$-$M_{\star }$-scale length (size) relation that is qualitatively consistent with observations. The inherent scatter in $j_{\star }$ provides a robust explanation for the mass-size relation and its substantial variability. Notably, galaxies that are moderately influenced by external processes closely adhere to a scaling relation akin to that of galaxies with tiny stellar halos. This result underscores the dominant role of internal processes in shaping the overall $j_{\star }$-$M_{\star }$ and mass-size relation, with external effects playing a relatively minor role in disk galaxies. Furthermore, the correlation between galaxy size and the virial radius of the dark matter halo exists but fails to provide strong evidence of the connection between galaxies and their parent dark matter halos.

11 pages, 9 figures, accepted for publication in A&A

References in corpus (27)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• The Structure of Classical Bulges And Pseudobulges: The Link Between Pseudobulges And Sersic Index
• The Size Evolution of Star-forming and Quenched Galaxies in the IllustrisTNG simulation
• A Revised Model for the Formation of Disk Galaxies: Low Spin and Dark-Halo Expansion
• Introducing the NewHorizon simulation: Galaxy properties with resolved internal dynamics across cosmic time
• Angular momentum evolution of galaxies in EAGLE
• Dissipation and Extra Light in Galactic Nuclei: III. 'Core' Ellipticals and 'Missing' Light
• Angular momentum properties of haloes and their baryon content in the Illustris simulation
• On the baryonic, stellar, and luminous scaling relations of disk galaxies
• The high mass end of the Tully-Fisher relation
• The baryonic specific angular momentum of disc galaxies
• Morphological decomposition of TNG50 galaxies: methodology and catalogue
• Galactic angular momentum in the IllustrisTNG simulation -- I. Connection to morphology, halo spin, and black hole mass
• Predicting the Properties of the Remnants of Dissipative Galaxy Mergers
• The Role of Dissipation in the Scaling Relations of Cosmological Merger Remnants
• Galaxy sizes and the galaxy-halo connection -- I: the remarkable tightness of the size distributions
• The Evolutionary Pathways of Disk-, Bulge-, and Halo-dominated Galaxies
• How to bend galaxy disc profiles: the role of halo spin
• The galaxy size to halo spin relation of disk galaxies in cosmological hydrodynamical simulations
• Modeling the Ages and Metallicities of Early-Type Galaxies in Fundamental Plane Space
• Smoothing Rotation Curves and Mass Profiles
• The Origin of the Relation Between Stellar Angular Momentum and Stellar Mass in Nearby Disk-dominated galaxies
• The relationship between galaxy and halo sizes in the Illustris and IllustrisTNG simulations
• Negligible Effects of Baryons on the Angular Momentum Scaling Relations of Galactic Dark Matter Halos

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• The evolutionary pathways of disk galaxies with different sizes
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• The Radio Spectral Energy Distribution and Star Formation Calibration in MIGHTEE-COSMOS Highly Star-Forming Galaxies at 1.5 < z < 3.5
• Introducing cosmosTNG: simulating galaxy formation with constrained realizations of the COSMOS field
• Bulgeless Evolution And the Rise of Discs (BEARD) I. Physical drivers of the mass-size relation for Milky Way-like galaxies
• The weak connection between the stellar haloes and merger histories of Milky Way-mass galaxies
• Bulgeless Evolution And the Rise of Discs (BEARD) II. The role of mergers in shaping the Milky Way analogues in TNG50
• COSMOS-Web: Galaxy Size and Surface Brightness Evolution at Rest-Frame 1.22 $\mu$m Since $z=3$