Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Kormendy, John; Kennicutt, Robert C.

doi:10.1146/annurev.astro.42.053102.134024

Cited by 1,763 publications

(2,489 citation statements)

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“…Ko- Table 8. Table shows rmendy & Kennicutt 2004;Fisher & Drory 2011). Considering all these implications for the galaxies in our sample, it is likely that internal processes are in many cases responsible for the formation of stars and driving the gas into the nuclear regions to feed black holes in their centre.…”

Section: Interpretation Of the Correlation Between Sfr And Agn Powermentioning

confidence: 87%

Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

Gürkan¹,

Hardcastle²,

Jarvis³

et al. 2015

Mon. Not. R. Astron. Soc.

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We examine the relationship between star formation and AGN activity by constructing matched samples of local (0 < z < 0.6) radio-loud and radio-quiet AGN in the Herschel-ATLAS fields. Radio-loud AGN are classified as high-excitation and low-excitation radio galaxies (HERGs, LERGs) using their emission lines and WISE 22-µm luminosity. AGN accretion and jet powers in these active galaxies are traced by [OIII] emission-line and radio luminosity, respectively. Star formation rates (SFRs) and specific star formation rates (SSFRs) were derived using Herschel 250-µm luminosity and stellar mass measurements from the SDSS−MPA-JHU catalogue. In the past, star formation studies of AGN have mostly focused on high-redshift sources to observe the thermal dust emission that peaks in the far-infrared, which limited the samples to powerful objects. However, with Herschel we can expand this to low redshifts. Our stacking analyses show that SFRs and SSFRs of both radio-loud and radioquiet AGN increase with increasing AGN power but that radio-loud AGN tend to have lower SFR. Additionally, radio-quiet AGN are found to have approximately an order of magnitude higher SSFRs than radio-loud AGN for a given level of AGN power. The difference between the star formation properties of radio-loud and -quiet AGN is also seen in samples matched in stellar mass.

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Section: Interpretation Of the Correlation Between Sfr And Agn Powermentioning

confidence: 87%

Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

Gürkan¹,

Hardcastle²,

Jarvis³

et al. 2015

Mon. Not. R. Astron. Soc.

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“…Similar criteria were used by, e. g., Begeman (1987) and de Blok et al (2008). Oval distortions (Bosma 1978;Kormendy 1982;Kormendy & Kennicutt 2004) can lead to incorrect estimates of inclinations for the more face-on galaxies. We retained four i < 40 • galaxies from ABP (M 101, NGC 5236, NGC 6946, and IC 342) because they provide leverage at high luminosities.…”

Section: Galaxy Selection Criteriamentioning

confidence: 99%

Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies

Kormendy

Freeman

2014

Proc. IAU

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Published mass models fitted to kinematic data are used to study the systematic properties of dark matter (DM) halos in Sc -Im and dwarf spheroidal (dSph) galaxies. Halo parameters are derived for rotationally supported galaxies by decomposing rotation curves V (r) into visible-and dark-matter contributions. The visible matter potential is calculated from the surface brightness assuming that the mass-to-light ratio M/L is constant with radius. "Maximum disk" values of M/L are adjusted to fit as much of the inner rotation curve as possible without making the halo have a hollow core. Rotation curve decomposition is impossible fainter than absolute magnitude M B ≃ −14, where V becomes comparable to the velocity dispersion of the gas. To increase the luminosity range further, we include central densities of dSph and dIm galaxies estimated via the Jeans equation for their stars (dSph) or H I (dIm). Combining these data, we find that DM halos satisfy well defined scaling laws analogous to the "fundamental plane" relations for elliptical galaxies. Halos in less luminous galaxies have smaller core radii r c , higher central densities ρ • , and smaller central velocity dispersions σ. Scaling laws provide new constraints on the nature of DM and on galaxy formation and evolution:1. A continuous sequence of decreasing mass extends from the highest-luminosity Sc I galaxies with M B ≃ −22.4 (H 0 = 70 km s −1 Mpc −1 ) to the lowest-luminosity galaxy with sufficient data (an ultrafaint dSph with M B ≃ −1).2. The high DM densities in dSph galaxies are normal for such tiny galaxies. Because virialized DM density depends on collapse redshift z coll , ρ • ∝ (1 + z coll ) 3 , and because the DM densities in the faintest dwarfs are about 500 times higher than those in the brightest spirals, therefore the collapse redshifts of the faintest dwarfs and the brightest spirals are related by (1 + z dwarf )/(1 + z spiral ) ≃ 8.3. The high DM densities in the dSph companions of our Galaxy imply that they are real galaxies formed from primordial density fluctuations. They are not tidal fragments. Tidal dwarfs cannot retain even the low DM densities of their giant-galaxy progenitors. In contrast, dSph galaxies generally have higher DM densities than those of possible giant-galaxy progenitors.4. We show explicitly that spiral, irregular, and spheroidal galaxies with M V > ∼ −18 form a sequence of decreasing baryon-to-DM surface density with decreasing luminosity. We suggest that these dS, dIm, and dSph galaxies form a sequence of decreasing baryon retention (caused by supernova-driven winds) or decreasing baryon capture (after cosmological reionization) in smaller galaxies.5. In all structural parameter correlations, dS+Im and dSph galaxies behave similarly; any differences between them are small. We conclude that the difference between z ∼ 0 galaxies that still contain gas (and that still can form stars) and those that do not (and that cannot form stars) is a second-order effect.The primary effect appears to be the physics that control...

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“…A more detailed comparison of a barred simulation with kinematics from the BRAVA survey (Howard et al 2008;Kunder et al 2012) by Shen et al (2010) noted that the velocity and velocity dispersion profiles can be reproduced provided a slowly rotating bulge component constitutes less than 8% of the disc mass. Thus, these properties all favour the presence of a bulge formed by the vertical thickening of the bar (see the reviews of Kormendy & Kennicutt (2004) and Fisher & Drory (2016)). …”

Section: Introductionmentioning

confidence: 99%

Separation of stellar populations by an evolving bar: implications for the bulge of the Milky Way

Debattista

Ness

Gonzalez

et al. 2017

Monthly Notices of the Royal Astronomical Society

157

255

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We present a novel interpretation of the previously puzzling different behaviours of stellar populations of the Milky Way's bulge. We first show, by means of pure N -body simulations, that initially co-spatial stellar populations with different in-plane random motions separate when a bar forms. The radially cooler populations form a strong bar, and are vertically thin and peanut-shaped, while the hotter populations form a weaker bar and become a vertically thicker box. We demonstrate that it is the radial, not the vertical, velocity dispersion that dominates this evolution. Assuming that early stellar discs heat rapidly as they form, then both the in-plane and vertical random motions correlate with stellar age and chemistry, leading to different density distributions for metal-rich and metal-poor stars. We then use a high-resolution simulation, in which all stars form out of gas, to demonstrate that this is what happens. When we apply these results to the Milky Way we show that a very broad range of observed trends for ages, densities, kinematics and chemistries, that have been presented as evidence for contradictory paths to the formation of the bulge, are in fact consistent with a bulge which formed from a continuum of disc stellar populations which were kinematically separated by the bar. For the first time we are able to account for the bulge's main trends via a model in which the bulge formed largely in situ. Since the model is generic, we also predict the general appearance of stellar population maps of external edge-on galaxies.

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Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Cited by 1,763 publications

References 432 publications

Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies

Separation of stellar populations by an evolving bar: implications for the bulge of the Milky Way

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