The Origin of Massive Compact Galaxies: Lessons from IllustrisTNG

Abstract

We investigate the formation and evolution of z=0 massive compact galaxies (MCGs) in the IllustrisTNG cosmological simulation. We found that, as in observations, MCGs are mainly old (median age $\sim 10.8$ Gyr), have super-solar metallicities (median $\log Z/Z_{\odot }\sim 0.35$) and are $\alpha$-enhanced (median $[\alpha /Fe]\sim 0.25$). The age distribution extends to younger ages, however, and a few MCGs are as young as $\sim 7$ Gyr. In general, MCGs assemble their mass early and accrete low angular momentum gas, significantly increasing their mass while growing their size much slower. A small fraction of MCGs follow another evolutionary path, going through a compaction event, with their sizes shrinking by 40% or more. The accretion of low angular momentum gas leads to enhanced SMBH growth, and MCGs reach the threshold SMBH mass of $\log M_{\mathrm{BH}}\sim 10^{8.5}{M}_{\odot }$ - when kinetic AGN feedback kicks in and quenches the galaxy - earlier than non-compact galaxies. Comparing MCGs to a sample of median-sized quiescent galaxies matched in effective velocity dispersion, we find that their accretion histories are very different. 71% of MCGs do not merge after quenching compared to 37% of median-sized quiescent galaxies. Moreover, tracing these populations back in time, we find that at least a third of median-sized quiescent galaxies do not have a compact progenitor, underscoring that both dry mergers and progenitor bias effects are responsible for the differences in the kinematics and stellar population properties of MCGs and median-sized quiescent galaxies.

15 pages, 15 figures (not including appendices). Accepted for publication in the Monthly Notices of the Royal Astronomical Society

References in corpus (29)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• Properties of galaxies reproduced by a hydrodynamic simulation
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• Introducing the Illustris Project: the evolution of galaxy populations across cosmic time
• The SAURON project -- IX. A kinematic classification for early-type galaxies
• The SAURON project -- X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/sigma,epsilon) diagram with integral-field stellar kinematics
• Compaction and Quenching of High-z Galaxies in Cosmological Simulations: Blue and Red Nuggets
• The MaNGA Integral Field Unit Fiber Feed System for the Sloan 2.5 m Telescope
• A surprising abundance of massive quiescent galaxies at 3 < z < 5 in the first data from JWST CEERS
• The Carnegie-Irvine Galaxy Survey. III. The Three-Component Structure of Nearby Elliptical Galaxies
• How to quench a galaxy
• CANDELS: Elevated Black Hole Growth in the Progenitors of Compact Quiescent Galaxies at z~2
• Minor Mergers or Progenitor Bias? The Stellar Ages of Small and Large Quenched Early-Type Galaxies
• Galaxy mergers can rapidly shut down star formation
• The AMIGA sample of isolated galaxies. IV. A catalogue of neighbours around isolated galaxies
• Wet Compaction to a Blue Nugget: a Critical Phase in Galaxy Evolution
• Spatially resolved kinematics in the central 1 kpc of a compact star-forming galaxy at z=2.3 from ALMA CO observations
• Low Gas Fractions Connect Compact Star-Forming Galaxies to their z ~ 2 Quiescent Descendants
• Interacting galaxies in the IllustrisTNG simulations -- III: (the rarity of) quenching in post-merger galaxies
• INSPIRE: INvestigating Stellar Population In RElics -- I. Survey presentation and pilot program
• Testing the presence of multiple photometric components in nearby early-type galaxies using SDSS
• AGN accretion and black hole growth across compact and extended galaxy evolution phases
• Relic galaxy analogues in Illustris TNG50: the formation pathways of surviving red nuggets in a cosmological simulation
• Merger Signatures are Common, but not Universal, In Massive, Recently-Quenched Galaxies at z~0.7
• The Structural Evolution of Isolated Galaxies at Low Redshift in the IllustrisTNG Simulation

Cited by in corpus (4)

• Demographics of Tidal Disruption Events with L-Galaxies: I. Volumetric TDE rates and the abundance of Nuclear Star Clusters
• What drives the corpulence of galaxies? I. The formation of central compact dwarf galaxies in TNG50
• Gamma Analytical Modeling Evolution (GAME) I: The physical implications of deriving the stellar mass functions from z=0 to z=8
• Stealing galaxies from galaxy clusters