Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

By J. Kormendy, Robert C. Kennicutt Jr.. 2004

1,363 citations recorded by the source corpus.

▪ Abstract The Universe is in transition. At early times, galactic evolution was dominated by hierarchical clustering and merging, processes that are violent and rapid. In the far future, evolution will mostly be secular—the slow rearrangement of energy and mass that results from interactions involving collective phenomena such as bars, oval disks, spiral structure, and triaxial dark halos. Both processes are important now. This review discusses internal secular evolution, concentrating on one important consequence, the buildup of dense central components in disk galaxies that look like classical, merger-built bulges but that were made slowly out of disk gas. We call these pseudobulges. We begin with an “existence proof”—a review of how bars rearrange disk gas into outer rings, inner rings, and stuff dumped onto the center. The results of numerical simulations correspond closely to the morphology of barred galaxies. In the simulations, gas is transported to small radii, where it reaches high densities and...

Subfields: Astronomy and Astrophysics, Instrumentation

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. R. Dav'e
5. A. Dekel
6. C. Conroy
7. Volker Springel
8. Thomas J. Cox

In Instrumentation

1. P. Hopkins
2. L. Hernquist
3. M. Cappellari
4. A. Dekel
5. C. Conroy
6. R. Somerville
7. P. V. van Dokkum
8. R. Dav'e

Citations in the corpus

• Bar formation and evolution in disc galaxies with gas and a triaxial halo: morphology, bar strength and halo properties (2012, background): “An alternative would be a pseudobulge (as named by Kormendy & Kennicutt 2004) or discy bulge (as named by Athanassoula 2005b).”
• A LINK BETWEEN STAR FORMATION QUENCHING AND INNER STELLAR MASS DENSITY IN SLOAN DIGITAL SKY SURVEY CENTRAL GALAXIES (2013, background): “…gas-rich major mergers (e.g., Toomre & Toomre 1972), violent disk instabilities (e.g., Dekel et al. 2009; Ceverino et al. 2010; Cacciato et al. 2012), gas-rich minor mergers (e.g., Mihos & Hernquist 1994), and bar and related non-axisymmetric disk instabilities (e.g., Kormendy & Kennicutt 2004).”
• The Spitzer/IRAC view of black hole–bulge scaling relations (2010, background): “Pseudobulges are bulges which are photometrically and morphologically disk-like (possibly containing typical disk features such as bars, rings or ovals) and which present ’cool’ kinematics, dominated by rotation (Kormendy & Kennicutt 2004).”
• THE DEPENDENCE OF QUENCHING UPON THE INNER STRUCTURE OF GALAXIES AT 0.5 ⩽ z < 0.8 IN THE DEEP2/AEGIS SURVEY (2012, background): “According to Kormendy & Kennicutt (2004), bars are a major driver of secular evolution at the current epoch.”
• STELLAR VELOCITY DISPERSION MEASUREMENTS IN HIGH-LUMINOSITY QUASAR HOSTS AND IMPLICATIONS FOR THE AGN BLACK HOLE MASS SCALE (2013, methodology): “Following Kormendy & Kennicutt (2004), the galaxies were inspected for the presence of the following MBH–σ∗ Relation 9 pseudobulge indicators: flattened bulge morphology, the presence of a nuclear bar, a low (n 2) Sersic index, and the presence of copious dust and star formation in the nucleus…”
• The Sydney-AAO Multi-object Integral field spectrograph (2011, background): “Their formation pathways are also quite different, with true bulges built up by violent mergers, discs from gas accretion, and pseudo-bulges from secular evolution (Kormendy & Kennicutt 2004).”
• HST WFC3/IR OBSERVATIONS OF ACTIVE GALACTIC NUCLEUS HOST GALAXIES AT z ∼ 2: SUPERMASSIVE BLACK HOLES GROW IN DISK GALAXIES (2010, background): “The disk morphologies of the host galaxies point instead to secular processes (e.g., Kormendy & Kennicutt 2004) as most common growth mode.”
• Rapid Formation of Exponential Disks and Bulges at High Redshift from the Dynamical Evolution of Clump-Cluster and Chain Galaxies (2007, background): “There may be other ways to make bulges or pseudo-bulges (e.g., Fu, Huang, & Deng 2003; Athanassoula 2005; Kormendy & Kennicutt 2004), but only the present model has been observed at high redshift in each of the important stages.”
• Dynamical Blueprints for Galaxies (2008, result): “This result is in agreement with studies of bulges in late-type spiral galaxies (Andredakic et al. 1995; Courteau et al. 1996; MacArthur et al. 2003) and suggests that the Galaxy has a pseudobulge rather than a classical bulge (see Kormendy & Kennicutt 2004, for a review).”
• The Milky Way’s stellar disk (2013, background): “But the hierarchical assembly and secular evolution processes erase, or at least diffuse, dynamical memory with time (Wielen 1977; Sellwood & Binney 2002; Kormendy & Kennicutt 2004; Schönrich & Binney 2008; see Section 7).”
• Galaxy Zoo 2: detailed morphological classifications for 304,122 galaxies from the Sloan Digital Sky Survey (2013, background): “For example, bars, are known to drive gas inwards and are related to the growth of a central bulge (reviews are given in Kormendy & Kennicutt 2004; Masters et al. 2011).”
• What drives the growth of black holes (2011, background): “…it is possible that these late-type systems have never undergone a galaxy major merger, and a non-negligible fraction of the BH mass may be from the massive BH seed formation (e.g., Kormendy & Kennicutt 2004; Volonteri & Natarajan 2009; see §4.3 for the discussion of the formation of massive BHs).”
• BULGE GROWTH AND QUENCHING SINCE z = 2.5 IN CANDELS/3D-HST (2014, background): “…modeling, the higher number of de- 15 Since the choice of a Sérsic index value for the bulge profile has long been debated in the literature (see Kormendy & Kennicutt 2004 and references therein), we repeated our two-component fits, with the only change fixing n = 2 for the bulge component…”
• Structural and Star-forming Relations since z ∼ 3: Connecting Compact Star-forming and Quiescent Galaxies (2015, background): “…with dissipational processes ranging from major mergers (Hopkins et al. 2006; Hopkins et al. 2008), to violent gravitational instabilities (Dekel et al. 2009a; Dekel & Burkert 2014; Ceverino et al. 2010), and weaker secular instabilities (e.g., bars and spiral arms; Kormendy & Kennicutt 2004).”