The buildup of galaxies and their spheroids: the contributions of mergers, disc instabilities and star formation

Abstract

We use the GALFORM semi-analytical model of galaxy formation and the Planck-Millennium simulation to investigate the origins of stellar mass in galaxies and their spheroids. We compare the importance of mergers and disc instabilities, as well as the starbursts that they trigger. We find that the fraction of galaxy stellar mass formed \textit{ex situ} ($f_{\mathrm{ex}}$) increases sharply from $M_{\ast }=10^{11}$ M${}_{\odot }$ upwards, reaching $80\%$ at $M_{\ast }=10^{11.3}$ M${}_{\odot }$. For low-mass galaxies we find larger \textit{\textit{ex situ}} contributions at $z=0$ than in other models ($7$-$12\%$), with a decrease towards higher redshifts. The global \textit{ex situ} fraction of all stellar mass falls sharply with redshift, from $40\%$ at $z=0$ to $3\%$ at $z=10$. Major mergers contribute roughly half of the \textit{ex situ} mass, with minor mergers and smooth accretion of satellites both accounting for $\approx 25\%$, almost independent of stellar mass and redshift. Mergers dominate in building up high-mass ($M_{\ast ,\mathrm{sph}}>10^{11}$ M${}_{\odot }$) and low-mass ($M_{\ast ,\mathrm{sph}}<10^{8.5}$ M${}_{\odot }$) spheroids. Disc instabilities and their associated starbursts dominate for intermediate-mass spheroids ($10^{8.5}<M_{\ast ,\mathrm{sph}}<10^{11}$ M${}_{\odot }$) at $z=0$. The mass regime where pseudobulges dominate is in agreement with observed pseudobulge fractions, but the peak value in the pseudobulge fraction predicted by GALFORM is likely too high. The total contributions of disc instabilities and their starbursts are roughly equal at $z=0$, with the former dominating for lower-mass spheroids (peak at $M_{\ast ,\mathrm{sph}}=10^{9.5}$ M${}_{\odot }$) and the latter for higher-mass ones (peak at $M_{\ast ,\mathrm{sph}}=10^{10.5}$ M${}_{\odot }$).

arXiv commentAccepted for publication in MNRAS

References in corpus (126)

• Planck 2013 results. XVI. Cosmological parameters
• The cosmological simulation code GADGET-2
• The Global Schmidt Law in Star Forming Galaxies
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Populating a cluster of galaxies - I. Results at z=0
• The broken hierarchy of galaxy formation
• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Simulating Galaxy Formation with the IllustrisTNG Model
• Hierarchical Galaxy Formation
• The Star Formation Law in Nearby Galaxies on Sub-Kpc Scales
• Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
• Gasdynamics and Starbursts in Major Mergers
• The hierarchical formation of the brightest cluster galaxies
• Galactic star formation and accretion histories from matching galaxies to dark matter haloes
• From dwarf spheroidals to cDs: Simulating the galaxy population in a LCDM cosmology
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• Minor mergers and the size evolution of elliptical galaxies
• First Results from the TNG50 Simulation: The evolution of stellar and gaseous disks across cosmic time
• Resolving Cosmic Structure Formation with the Millennium-II Simulation
• Very High Gas Fractions and Extended Gas Reservoirs in z=1.5 Disk Galaxies
• Dancing in the dark: galactic properties trace spin swings along the cosmic web
• The Growth of Massive Galaxies Since z=2
• The merger rate of galaxies in the Illustris Simulation: a comparison with observations and semi-empirical models
• Galaxy formation in the Planck Cosmology - I. Matching the observed evolution of star formation rates, colours and stellar masses
• From rings to bulges: evidence for rapid secular galaxy evolution at z~2 from integral field spectroscopy in the SINS survey
• Structural Properties of Pseudo-Bulges, Classical Bulges and Elliptical Galaxies: an SDSS Perspective
• How Do Disks Survive Mergers?
• Galaxy Pairs in the Sloan Digital Sky Survey I: Star Formation, AGN Fraction, and the Luminosity/Mass-Metallicity Relation
• A primer on hierarchical galaxy formation: the semi-analytical approach
• The effect of galaxy mass ratio on merger--driven starbursts
• The Horizon-AGN simulation: morphological diversity of galaxies promoted by AGN feedback
• The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars
• The Secular Evolution of Disk Structural Parameters
• Can Minor Merging Account for the Size Growth of Quiescent Galaxies? New Results from the CANDELS Survey
• Mergers and Bulge Formation in Lambda-CDM: Which Mergers Matter?
• The Major and Minor Galaxy Merger Rates at z < 1.5
• EMERGE - An empirical model for the formation of galaxies since $z\sim 10$
• A unified multi-wavelength model of galaxy formation
• Major Galaxy Mergers Only Trigger the Most Luminous AGN
• Secular Evolution in Disk Galaxies
• The Structure of Classical Bulges And Pseudobulges: The Link Between Pseudobulges And Sersic Index
• Bulge Formation by the Coalescence of Giant Clumps in Primordial Disk Galaxies
• Excitation of Activity in Galaxies by Minor Mergers
• The Greater Impact of Mergers on the Growth of Massive Galaxies: Implications for Mass Assembly and Evolution Since z~1
• The Central Region of Barred Galaxies: Molecular Environment, Starbursts, and Secular Evolution
• Galaxy Pairs in the Sloan Digital Sky Survey - V. Tracing changes in star formation rate and metallicity out to separations of 80 kpc
• Gas Physics, Disk Fragmentation, and Bulge Formation in Young Galaxies
• The Effect of Mass Ratio on the Morphology and Time-scales of Disc Galaxy Mergers
• Galaxy And Mass Assembly (GAMA): Data Release 4 and the z < 0.1 total and z < 0.08 morphological galaxy stellar mass functions
• Clumpy Galaxies in CANDELS. I. The Definition of UV Clumps and the Fraction of Clumpy Galaxies at 0.5<z<3
• Galaxy growth in the concordance $\Lambda$CDM cosmology
• A calibration of the relation between the abundance of close galaxy pairs and the rate of galaxy mergers
• Bursting and Quenching in Massive Galaxies without Major Mergers or AGNs
• A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed
• A chronicle of galaxy mass assembly in the EAGLE simulation
• Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs
• The Fornax Deep Survey with VST. I. The extended and diffuse stellar halo of NGC~1399 out to 192 kpc
• A new model of galaxy formation: How sensitive are predicted galaxy luminosities to the choice of SPS model?
• N-body Dark Matter Haloes with simple Hierarchical Histories
• Ongoing Assembly of Massive Galaxies by Major Merging in Large Groups and Clusters from the SDSS
• Galaxy And Mass Assembly (GAMA): Galaxy close-pairs, mergers, and the future fate of stellar mass
• Effects of AGN feedback on LCDM galaxies
• Size Evolution of Spheroids in a Hierarchical Universe
• Quantifying the impact of mergers on the angular momentum of simulated galaxies
• Intracluster light and the extended stellar envelopes of cD galaxies: An analytical description
• The dominant role of mergers in the size evolution of massive early-type galaxies since z ~ 1
• Composite Bulges: The Coexistence of Classical Bulges and Disky Pseudobulges in S0 and Spiral Galaxies
• Galaxy Merger Statistics and Inferred Bulge-to-Disk Ratios in Cosmological SPH Simulations
• Demographics of Bulge Types within 11 Mpc and Implications for Galaxy Evolution
• Galaxy Mergers and Dark Matter Halo Mergers in LCDM: Mass, Redshift, and Mass-Ratio Dependence
• The evolution of spiral, S0 and elliptical galaxies in clusters
• Gas-Rich Mergers in LCDM: Disk Survivability and the Baryonic Assembly of Galaxies
• Galaxy Pairs in COSMOS -- Merger Rate Evolution Since z=1
• Galaxy morphology in the LambdaCDM cosmology
• Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies
• Galaxy formation in the Planck Millennium: the atomic hydrogen content of dark matter halos
• Morphology and Molecular Gas Fractions of Local Luminous Infrared Galaxies as a Function of Infrared Luminosity and Merger Stage
• A gravitationally unstable gas disk of a starburst galaxy 12 billion years ago
• Enhanced atomic gas fractions in recently merged galaxies: quenching is not a result of post-merger gas exhaustion
• Evolution of violent gravitational disc instability in galaxies: Late stabilization by transition from gas to stellar dominance
• A new criterion for Bar-Forming Instability in Rapidly Rotating Gaseous and Stellar Systems. I. Axisymmetric Form
• Galaxy And Mass Assembly (GAMA): the Stellar Mass Budget by Galaxy Type
• Secular- and merger-built bulges in barred galaxies
• How do galaxies acquire their mass?
• The three phases of galaxy formation
• VEGAS: A VST Early-type GAlaxy Survey. II. Photometric study of giant ellipticals and their stellar halos
• Pseudobulge Formation as a Dynamical Rather than a Secular Process
• Interacting galaxies in the IllustrisTNG simulations -- I: Triggered star formation in a cosmological context
• Early- and late-stage mergers among main sequence and starburst galaxies at 0.2<z<2
• The Effect of Galaxy Interactions on Molecular Gas Properties
• The host galaxies of X-ray selected Active Galactic Nuclei to z=2.5: Structure, star-formation and their relationships from CANDELS and Herschel/PACS
• The Fornax Deep Survey with VST. VIII. Connecting the accretion history with the cluster density
• An EAGLE's View of Ex-situ Galaxy Growth
• Galaxy pairs in the SDSS - XIII. The connection between enhanced star formation and molecular gas properties in galaxy mergers
• Bulges Of Nearby Galaxies With Spitzer: The Growth Of Pseudobulges In Disk Galaxies And Its Connection To Outer Disks
• A two-phase scenario for bulge assembly in LCDM cosmologies
• Constraints on the merging channel of massive galaxies since z~1
• Natures of a clump-origin bulge: a pseudobulge-like but old metal-rich bulge
• What powers the starburst activity of NGC 1068? Star-driven gravitational instabilities caught in the act
• Galaxy Gas Fractions at High-Redshift: The Tension between Observations and Cosmological Simulations
• The merger rates and sizes of galaxies across the peak epoch of star formation from the HiZELS survey
• EMERGE: Empirical predictions of galaxy merger rates since $z\sim 6$
• Galaxy merger histories and the role of merging in driving star formation at z>1
• The growth of disks and bulges during hierarchical galaxy formation. I: fast evolution vs secular processes
• Empirical constraints on the formation of early-type galaxies
• The origin of the mass scales for maximal star formation efficiency and quenching: the critical role of Supernovae
• Stellar mass functions of galaxies, disks and spheroids at z~0.1
• The evolution of the stellar mass versus halo mass relationship
• VEGAS: A VST Early-type GAlaxy Survey. III. Mapping the galaxy structure, interactions and intragroup light in the NGC 5018 group
• Caught in the Act: Direct Detection of Galactic Bars in the Buckling Phase
• Modelling Galaxy Merger Timescales and Tidal Destruction
• The build-up of pseudobulges in a hierarchical universe
• Mass growth and mergers: direct observations of the luminosity function of LRG satellite galaxies out to z=0.7 from SDSS and BOSS images
• Statistics of galaxy mergers: bridging the gap between theory and observation
• VEGAS: VST Early-type GAlaxy Survey. V. IC 1459 group: Mass assembly history in low density environments
• Structural and Stellar Population Properties vs. Bulge Types in Sloan Digital Sky Survey Central Galaxies
• VEGAS: a VST Early-type GAlaxy Survey. IV. NGC 1533, IC 2038 and IC 2039: an interacting triplet in the Dorado group
• The far infra-red SEDs of main sequence and starburst galaxies
• Properties of Molecular Gas in Galaxies in Early and Mid Stage of Interaction: II. Molecular Gas Fraction
• A new methodology to test galaxy formation models using the dependence of clustering on stellar mass
• Morphological evolution and galactic sizes in the L-Galaxies SA model
• A Spitzer Study of Pseudobulges in S0 Galaxies : Secular Evolution of Disks
• The NGC 4013 tale: a pseudo-bulged, late-type spiral shaped by a major merger
• Formation and assembly history of stellar components in galaxies as a function of stellar and halo mass
• On the assembly history of massive galaxies. A pilot project with VEGAS deep imaging and M3G integral field spectroscopy
• MOSEL Survey: Tracking the Growth of Massive Galaxies at 2<z<4 using Kinematics and the IllustrisTNG Simulation

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• JWST reveals a possible $z\sim 11$ galaxy merger in triply-lensed MACS0647$-$JD
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• The $z\lesssim 1$ drop of cosmic dust abundance in a semi-analytic framework
• X-ray AGN in Boötes: The lack of growth of the most massive black holes since z=4
• Superbubbles as the source of dynamical friction: gas migration, stellar and dark matter contributions