The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies

Krajnović, Davor; Emsellem, Éric; Cappellari, Michele; Alatalo, Katherine; Blitz, Leo; Bois, Maxime; Bournaud, F.; Bureau, Martin; Davies, Roger L.; Davis, Timothy A.; Zeeuw, P. T. de; Khochfar, Sadegh; Küntschner, H.; Lablanche, Pierre Yves; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, P.; Weijmans, Anne-Marie; Young, Lisa M.

doi:10.1111/j.1365-2966.2011.18560.x

Cited by 471 publications

(743 citation statements)

References 97 publications

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“…Or the two vectors may not align because we are observing the systems in projection (the orientation of a triaxial galaxy towards an observer is random). Interestingly, analysis presented by Franx et al (1991) showed that majority of early-type galaxies indeed had small misalignments (See also, Krajnović et al 2011). The most modern estimates on elliptical galaxy spin axes claim that a majority of elliptical galaxies appear like spiral galaxies with the gas and dust removed (Cappellari et al 2011), namely with spin vectors aligned with their short axes.…”

Section: Observational Samples and Galaxy Spin Vectorsmentioning

confidence: 99%

The alignment of galaxy spin with the shear field in observations

Pahwa

Libeskind

Tempel

et al. 2016

Mon. Not. R. Astron. Soc.

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Tidal torque theory suggests that galaxies gain angular momentum in the linear stage of structure formation. Such a theory predicts alignments between the spin of haloes and tidal shear field. However, non-linear evolution and angular momentum acquisition may alter this prediction significantly. In this paper, we use a reconstruction of the cosmic shear field from observed peculiar velocities combined with spin axes extracted from galaxies within 115 Mpc (∼ 8000 kms −1 ) from 2MRS catalog, to test whether or not galaxies appear aligned with principal axes of shear field. Although linear reconstructions of the tidal field have looked at similar issues, this is the first such study to examine galaxy alignments with velocity-shear field. Ellipticals in the 2MRS sample, show a statistically significant alignment with two of the principal axes of the shear field. In general, elliptical galaxies have their short axis aligned with the axis of greatest compression and perpendicular to the axis of slowest compression. Spiral galaxies show no signal. Such an alignment is significantly strengthened when considering only those galaxies that are used in velocity field reconstruction. When examining such a subsample, a weak alignment with the axis of greatest compression emerges for spiral galaxies as well. This result indicates that although velocity field reconstructions still rely on fairly noisy and sparse data, the underlying alignment with shear field is strong enough to be visible even when small numbers of galaxies are considered -especially if those galaxies are used as constraints in the reconstruction.

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Section: Observational Samples and Galaxy Spin Vectorsmentioning

confidence: 99%

The alignment of galaxy spin with the shear field in observations

Pahwa

Libeskind

Tempel

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Integral field kinematic data from the ATLAS 3D are available for NGC 4371 and NGC 3945 (Krajnović et al 2011). Fig.…”

Section: Kinematic Comparisonsmentioning

confidence: 99%

The formation of stellar nuclear discs in bar-induced gas inflows

Cole

Debattista

Erwin

et al. 2014

Monthly Notices of the Royal Astronomical Society

123

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The role of gas in the mass assembly at the nuclei of galaxies is still subject to some uncertainty. Stellar nuclear discs bridge the gap between the large-scale galaxy and the central massive objects that reside there. Using a high resolution simulation of a galaxy forming out of gas cooling and settling into a disc, we study the formation and properties of nuclear discs. Gas, driven to the centre by a bar, settles into a rotating star-forming nuclear disc (ND). This ND is thinner, younger, kinematically cooler, and more metal-rich than the surrounding bar. The ND is elliptical and orthogonal to the bar. The complex kinematics in the region of the ND are a result of the superposition of older stars streaming along the bar and younger stars circulating within the ND. The signature of the ND is therefore subtle in the kinematics. Instead the ND stands out clearly in metallicity and age maps. We compare the model to the density and kinematics of real galaxies with NDs finding qualitative similarities. Our results suggest that gas dissipation is very important for forming nuclear structures.

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“…One extreme example is the kinematically decoupled core found in some massive, early-type galaxies (e.g., Krajnović et al 2011) and in a few low-mass, early-type galaxies (e.g., Thomas et al 2006;Chilingarian et al 2007;Toloba et al 2014b, Gérou et al, 2015. These could be remnants of galaxy mergers or gas accretion, and are thus good indicators of the formation history of the galaxy.…”

Section: Introductionmentioning

confidence: 99%

The Next Generation Virgo Cluster Survey Xvi: The Angular Momentum of Dwarf Early-Type Galaxies From Globular Cluster Satellites

Toloba

Guhathakurta

et al. 2016

ApJ

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We analyze the kinematics of six Virgo cluster dwarf early-type galaxies (dEs) from their globular cluster (GC) systems. We present new Keck/DEIMOS spectroscopy for three of them and re-analyze the data found in the literature for the remaining three. We use two independent methods to estimate the rotation amplitude (V rot ) and velocity dispersion (σ GC ) of the GC systems and evaluate their statistical significance by simulating non-rotating GC systems with the same number of GC satellites and velocity uncertainties. Our measured kinematics agree with the published values for the three galaxies from the literature and, in all cases, some rotation is measured. However, our simulations show that the null hypothesis of being non-rotating GC systems cannot be ruled out. In the case of VCC1861, the measured V rot and the simulations indicate that it is not rotating. In the case of VCC1528, the null hypothesis can be marginally ruled out, and thus it might be rotating although further confirmation is needed. In our analysis, we find that, in general, the measured V rot tends to be overestimated and the measured σ GC tends to be underestimated by amounts that depend on the intrinsic V rot /σ GC , the number of observed GCs (N GC ), and the velocity uncertainties. The bias is negligible when N GC  20. In those cases where a large N GC is not available, it is imperative to obtain data with small velocity uncertainties. For instance, errors of 2 km s −1 lead to V rot < 10 km s −1 for a system that is intrinsically not rotating.

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The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies

Cited by 471 publications

References 97 publications

The alignment of galaxy spin with the shear field in observations

The alignment of galaxy spin with the shear field in observations

The formation of stellar nuclear discs in bar-induced gas inflows

The Next Generation Virgo Cluster Survey Xvi: The Angular Momentum of Dwarf Early-Type Galaxies From Globular Cluster Satellites

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