The origin of pseudobulges in cosmological simulations of galaxy formation

Abstract

More than half of nearby disc galaxies have pseudobulges instead of classical bulges that are though to be end-products of galaxy mergers. Pseudobulges are presumed to develop overtime as a result of secular evolution of galaxy discs. We report simulations of galaxy formation, in which two disc galaxies with disky pseudobulges have formed. Based on the profile decomposition, the bulge-to-total mass ratio of the simulated galaxies is 0.6 for one galaxy and 0.3 for the other. We find that the main formation mechanism of the pseudobulges in our simulations is not the secular evolution of discs but high-redshift starbursts. The progenitors of the pseudobulges form as high-redshift discs with small scale lengths by rapid supply of low angular momentum gas. By redshift 2, before the main disc formation, pseudobulge formation has largely completed in terms of mass. The secular evolution such as bar instability accounts for about 30 % of the bulge mass for one galaxy and only 13 % for the other but does affect the final shape and kinematic properties of the pseudobulges.

12 pages, 14 figures, accepted for publication in MNRAS. Movies can be found at http://www.ccs.tsukuba.ac.jp/Astro/Members/takashi/research/movies.html#pseudobulges"

References in corpus (10)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• The effect of photo-ionization on the cooling rates of enriched, astrophysical plasmas
• Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows
• Forming Disk Galaxies in Lambda CDM Simulations
• Massloss of galaxies due to a UV-background
• Modelling discontinuities and Kelvin-Helmholtz instabilities in SPH
• The Structure of Classical Bulges And Pseudobulges: The Link Between Pseudobulges And Sersic Index
• The formation and assembly of a typical star-forming galaxy at z~3
• The origin of failed subhaloes and the common mass scale of the Milky Way satellite galaxies
• The impact of radio feedback from active galactic nuclei in cosmological simulations: Formation of disk galaxies

Cited by in corpus (11)

• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
• The Bulge Metallicity Distribution from the APOGEE Survey
• The diverse formation histories of simulated disc galaxies
• Dissecting galactic bulges in space and time I: the importance of early formation scenarios vs. secular evolution
• Reproducing cosmic evolution of galaxy population from $z=4$ to $0$
• The central spheroids of Milky Way mass-sized galaxies
• The continuous rise of bulges out of galactic disks
• Cosmic evolution of bars in simulations of galaxy formation
• The metal enrichment of passive galaxies in cosmological simulations of galaxy formation
• Dark matter halos of barred disk galaxies
• Spiral Galaxies as Progenitors of Pseudobulge Hosting S0s