Kinematic properties of gas and stars in 20 disc galaxies

Beltrán, J. C. Vega; Pizzella, A.; Corsini, E. M.; Funes, J. G.; Zeilinger, W. W.; Beckman, J. E.; Bertola, F.

doi:10.1051/0004-6361:20010625

Cited by 79 publications

(96 citation statements)

References 61 publications

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“…NGC 5854 is classified Sa in Sandage & Bedke (1994), who note, "The inner spiral pattern [of two] is in the bulge (it forms the bulge) and has the form and the sense of the opening of a stubby S." This observation is more consistent with a pseudobulge than with a classical bulge. Spiral structure requires a dynamically cold system, and indeed, the weighted mean of the best velocity dispersion measurements is 102 ± 4 km s −1 (Simien & Prugneil 1997;Vega Beltrán et al 2001;Falcón-Barroso, Peletier, & Balcells 2002). The second "young" bulge is in the S0 galaxy NGC 7457; showed that it has an unusually small velocity dispersion indicative of a pseudobulge.…”

Section: Stellar Populations In Classical Bulges and Pseudobulgesmentioning

confidence: 99%

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Kormendy¹,

Kennicutt

2004

Annu. Rev. Astron. Astrophys.

1,761

107

2,359

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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 paper reviews 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. Simulation results correspond closely to the morphology of barred galaxies. In the simulations, gas transported to small radii reaches high densities that plausibly feed star formation. In the observations, many SB and oval galaxies have dense central concentrations of gas and star formation. Optical colors and spectra often imply young stellar populations. So the formation of pseudobulges is well supported by theory and observations. It is embedded in a broader evolution picture that accounts for much of the richness observed in galaxy structure.If secular processes built dense central components that masquerade as bulges, how can we distinguish them from merger-built bulges? Observations show that pseudobulges retain a memory of their disky origin. 2That is, they have one or more characteristics of disks: (1) flatter shapes than those of classical bulges, (2) correspondingly large ratios of ordered to random velocities indicative of disk dynamics, (3) small velocity dispersions σ with respect to the Faber-Jackson correlation between σ and bulge luminosity, (4) spiral structure or nuclear bars in the "bulge" part of the light profile, (5) nearly exponential brightness profiles, and (6) starbursts. These structures occur preferentially in barred and oval galaxies in which secular evolution should be most rapid. So the cleanest examples of pseudobulges are recognizable.Are their formation timescales plausible? We use measurements of central gas densities and star formation rates to show that pseudobulges of the observed densities form on reasonable timescales of a few billion years.Thus a large variety of observational and theoretical results contribute to a new picture of galaxy evolution that complements hierarchical clustering and merging. Secular evolution consists of more than the aging of stellar populations. Every galaxy is dynamically evolving.

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Section: Stellar Populations In Classical Bulges and Pseudobulgesmentioning

confidence: 99%

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Kormendy¹,

Kennicutt

2004

Annu. Rev. Astron. Astrophys.

1,761

107

2,359

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“…We supplemented our sample by adding host galaxies whose rotation sense was determined from the spectroscopic observations in the literature (Rubin et al 1982(Rubin et al , 1985(Rubin et al , 1999Broeils & van Woerden 1994;Han et al 1995;Taylor et al 1995;Rhee & van Albada 1996;Zaritsky et al 1997;Sofue 1997;Sofue et al 1997Sofue et al , 1998Sofue et al , 2003Héraudeau & Simien 1998;Héraudeau et al 1999;Vega Beltrán et al 2001;Garrido et al 2002Garrido et al , 2003Garrido et al , 2004Garrido et al , 2005Vogt et al 2004;Coccato et al 2004;Fridman et al 2005;Hernandez et al 2005;Noordermeer et al 2005;Chemin et al 2006;Falcón-Barroso et al 2006;Daigle et al 2006;Ganda et al 2006;Azzaro et al 2006;Herbert-Fort et al 2008;Epinat et al 2008aEpinat et al , 2008bSwaters et al 2009). We compiled 390 satellites associated with 116 hosts.…”

Section: Spin Direction Of Host Galaxiesmentioning

confidence: 99%

Orbital Dependence of Galaxy Properties in Satellite Systems of Galaxies

Hwang

Park

2010

ApJ

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We study the dependence of satellite galaxy properties on the distance to the host galaxy and the orbital motion (prograde and retrograde orbits) using the Sloan Digital Sky Survey (SDSS) data. From SDSS Data Release 7, we find 3515 isolated satellite systems of galaxies at z < 0.03 that contain 8904 satellite galaxies. Using this sample, we construct a catalog of 635 satellites associated with 215 host galaxies whose spin directions are determined by our inspection of the SDSS color images and/or by spectroscopic observations in the literature. We divide satellite galaxies into prograde and retrograde orbit subsamples depending on their orbital motion with respect to the spin direction of the host. We find that the number of galaxies in prograde orbit is nearly equal to that of retrograde orbit galaxies: the fraction of satellites in prograde orbit is 50% ± 2%. The velocity distribution of satellites with respect to their hosts is found to be almost symmetric: the median bulk rotation of satellites is −1 ± 8 km s −1 . It is found that the radial distribution of early-type satellites in prograde orbit is strongly concentrated toward the host while that of retrograde ones shows much less concentration. We also find the orbital speed of late-type satellites in prograde orbit increases as the projected distance to the host (R) decreases while the speed decreases for those in retrograde orbit. At R less than 0.1 times the host virial radius (R < 0.1r vir,host ), the orbital speed decreases in both prograde and retrograde orbit cases. Prograde satellites are on average fainter than retrograde satellites for both early and late morphological types. The u − r color becomes redder as R decreases for both prograde and retrograde orbit late-type satellites. The differences between prograde and retrograde orbit satellite galaxies may be attributed to their different origin or the different strength of physical processes that they have experienced through hydrodynamic interactions with their host galaxies.

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“…In elliptical galaxies, V/σ is usually estimated via the ratio of the maximal rotational velocity to the mean velocity dispersion within 0.5r e , where r e is the effective radius of the system (e.g., Davies et al 1983;Bender et al 1994). For spiral galaxies, there is no general consensus: different spatial components of σ, estimated following different methods, have been used (e.g., Bottema 1993;Vega Beltrán et al 2001;Hunter et al 2005). Binney (2005) demonstrates that with integral field spectroscopy (i.e., a 2-dimensional spatial coverage combined with simultaneous spectral coverage), the intrinsic V/σ is more robustly estimated using the ratio between the mean squared rotational velocity and the mean squared velocity dispersion, both measured directly along the line of sight.…”

Section: Dynamical Support Of Distant Disk Galaxiesmentioning

confidence: 99%

“…In the case of local galaxies, if we assume both a well-aligned slit and well-coupled gas and stars dynamics (see Vega Beltrán et al 2001;Pizzella et al 2004), one gets σ obs ∼ σ z . In the case of distant galaxies, observed using integral field spectroscopy, it is necessary to correct for the different η corresponding to the different IFU pixels.…”

Section: Dynamical Support Of Distant Disk Galaxiesmentioning

confidence: 99%

3D spectroscopy with VLT/GIRAFFE

Puech¹,

Hammer²,

Lehnert

et al. 2007

A&A

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Context. One of the most outstanding problems related to numerical models of galaxy formation is the so-called "angular momentum catastrophe", i.e., the inability to theoretically explain the high angular momentum observed in local disk galaxies. Aims. We study the evolution of the angular momentum from z ∼ 0.6 to z = 0 to better understand the mechanisms responsible for the large angular momenta of disk galaxies observed today. This study is based on a complete sample of 32, 0.4 ≤ z ≤ 0.75 galaxies observed with FLAMES/GIRAFFE at the VLT. Their kinematics had been classified as rotating disks (11 galaxies), perturbed rotators (7 galaxies), or complex kinematics (14 galaxies). Methods. We have computed the specific angular momentum of disks ( j disk ) and the dynamical support of rotating disks through the V/σ ratio. To study how angular momentum can be acquired dynamically, we compared the properties of distant and local galaxies, as a function of their kinematical class. Results. We find that distant rotating disks have essentially the same properties ( j disk and R d ) as local disks, while distant galaxies with more complex kinematics have a significantly higher scatter in the j disk -V max and R d -V max planes. On average, distant galaxies show lower values of V/σ than local galaxies, the lowest V/σ values being reached by distant galaxies showing perturbed rotation. This can probably be attributed to heating mechanisms at work in distant disks. Conclusions. We found observational evidence for a non-linear random-walk evolution of the angular momentum in galaxies during the past 8 Gyr. The evolution related to galaxies with complex kinematics can be attributed to mergers, but not to (smooth) gas accretion alone. If galaxies observed at intermediate redshift are related to present-day spirals, then our results match the "spiral rebuilding" scenario proposed by Hammer et al. (2005) quite closely.

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Kinematic properties of gas and stars in 20 disc galaxies

Cited by 79 publications

References 61 publications

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Secular Evolution and the Formation of Pseudobulges in Disk Galaxies

Orbital Dependence of Galaxy Properties in Satellite Systems of Galaxies

3D spectroscopy with VLT/GIRAFFE

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