Overview of the Near-IR S0 Galaxy Survey (NIRS0S)

Laurikainen, Eija; Salo, H.; Buta, Ronald J.; Knapen, Johan H.

doi:10.1155/2011/516739

Cited by 10 publications

(19 citation statements)

References 79 publications

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“…Fast rotators have similar intrinsic flattening as spiral galaxies, which is in line with the results of Paper XVII, where we showed that fast rotators show a large span in disc-to-total ratios, and with the classification scheme introduced by Van den Bergh (1976), and revisited in Paper VII to emphasize the parallelism between fast rotators and spirals (see also Laurikainen et al 2011;Kormendy & Bender 2012). This observation could hint to a similar evolutionary path of spirals and fast rotators, and it would be interesting to study this further in the context of the morphologydensity relation, as mentioned in e.g.…”

Section: Discussionsupporting

confidence: 91%

The ATLAS 3D project – XXIV. The intrinsic shape distribution of early-type galaxies

Weijmans

Zeeuw

Emsellem

et al. 2014

Monthly Notices of the Royal Astronomical Society

126

188

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We use the ATLAS 3D sample to perform a study of the intrinsic shapes of early-type galaxies, taking advantage of the available combined photometric and kinematic data. Based on our ellipticity measurements from the Sloan Digital Sky Survey Data Release 7, and additional imaging from the Isaac Newton Telescope, we first invert the shape distribution of fast and slow rotators under the assumption of axisymmetry. The so-obtained intrinsic shape distribution for the fast rotators can be described with a Gaussian with a mean flattening of q = 0.25 and standard deviation σ q = 0.14, and an additional tail towards rounder shapes. The slow rotators are much rounder, and are well described with a Gaussian with mean q = 0.63 and σ q = 0.09. We then checked that our results were consistent when applying a different and independent method to obtain intrinsic shape distributions, by fitting the observed ellipticity distributions directly using Gaussian parametrisations for the intrinsic axis ratios. Although both fast and slow rotators are identified as early-type galaxies in morphological studies, and in many previous shape studies are therefore grouped together, their shape distributions are significantly different, hinting at different formation scenarios. The intrinsic shape distribution of the fast rotators shows similarities with the spiral galaxy population. Including the observed kinematic misalignment in our intrinsic shape study shows that the fast rotators are predominantly axisymmetric, with only very little room for triaxiality. For the slow rotators though there are very strong indications that they are (mildly) triaxial.

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Section: Discussionsupporting

confidence: 91%

The ATLAS 3D project – XXIV. The intrinsic shape distribution of early-type galaxies

Weijmans

Zeeuw

Emsellem

et al. 2014

Monthly Notices of the Royal Astronomical Society

126

188

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“…Graham 2001;MacArthur et al 2003;Weinzirl et al 2009;Laurikainen et al 2010), and strongly suggest an evolutionary link. Our results support the revision of the Hubble diagram put forward initially by van den Bergh (1976), which we revised to include fast and slow rotators in Paper VII (for photometric investigations see Laurikainen et al (2011) and Kormendy & Bender (2012)).…”

Section: Similarities Of Fast Rotators Galaxies and Spiralssupporting

confidence: 87%

The ATLAS3D project – XVII. Linking photometric and kinematic signatures of stellar discs in early-type galaxies

Krajnović

Alatalo

Blitz

et al. 2012

Monthly Notices of the Royal Astronomical Society

161

190

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We analyse the morphological structures in galaxies of the ATLAS 3D sample by fitting a single Sérsic profile and decomposing all non-barred objects (180 of 260 objects) in two components parameterised by an exponential and a general Sérsic function. The aim of this analysis is to look for signatures of discs in light distributions of nearby early-type galaxies and compare them to kinematic properties. Using Sérsic index from single component fits for a distinction between slow and fast rotators, or even late-and early-type galaxies, is not recommended. Assuming that objects with n > 3 are slow rotators (or ellipticals), there is only a 22 per cent probability to correctly classify objects as slow rotators (or 37 per cent of previously classified as ellipticals). We show that exponential sub-components, as well as light profiles fitted with only a single component of a low Sérsic index, can be linked with the kinematic evidence for discs in early-type galaxies. The median disk-to-total light ratio for fast and slow rotators is 0.41 and 0.0, respectively. Similarly, the median Sérsic indices of the bulge (general Sérsic component) are 1.7 and 4.8 for fast and slow rotators, respectively. Overall, discs or disclike structures, are present in 83 per cent of early-type galaxies which do not have bars, and they show a full range of disk-to-total light ratios. Discs in early-type galaxies contribute with about 40 per cent to the total mass of the analysed (non-barred) objects. The decomposition into discs and bulges can be used as a rough approximation for the separation between fast and slow rotators, but it is not a substitute, as there is only a 59 per cent probability to correctly recognise slow rotators. We find trends between the angular momentum and the disc-to-total light ratios and the Sérsic index of the bulge, in the sense that high angular momentum galaxies have large disc-to-total light ratios and small bulge indices, but there is none between the angular momentum and the global Sérsic index. We investigate the inclination effects on the decomposition results and confirm that strong exponential profiles can be distinguished even at low inclinations, but medium size discs are difficult to quantify using photometry alone at inclinations lower than ∼ 50 • . Kinematics (i.e. projected angular momentum) remains the best approach to mitigate the influence of the inclination effects. We also find weak trends with mass and environmental density, where disc dominated galaxies are typically less massive and found at all densities, including the densest region sampled by the ATLAS 3D sample.

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“…We showed that the true parallelism is the one between fast rotator ETGs and spirals instead (Cappellari et al 2011b, hereafter Paper VII). Similar conclusions were also reached using photometry by Laurikainen et al (2011) and Kormendy & Bender (2012).…”

Section: Introductionsupporting

confidence: 79%

The ATLAS3D Project – XXIII. Angular momentum and nuclear surface brightness profiles

Krajnović

Karick

Davies

et al. 2013

Monthly Notices of the Royal Astronomical Society

148

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We investigate nuclear light profiles in 135 ATLAS 3D galaxies for which the Hubble Space Telescope (HST) imaging is available and compare them to the large scale kinematics obtained with the SAURON integral-field spectrograph. Specific angular momentum, λ R , correlates with the shape of nuclear light profiles, where, as suggested by previous studies, cores are typically found in slow rotators and core-less galaxies are fast rotators. As also shown before, cores are found only in massive galaxies and only in systems with the stellar mass (measured via dynamical models) M 8 × 10 10 M ⊙ . Based on our sample, we, however, see no evidence for a bimodal distribution of nuclear slopes. The best predictor for finding a core is based on the stellar velocity dispersion within an effective radius, σ e , and specific angular momentum, where cores are found for λ R 0.25 and σ e 160 km/s. We estimate that only about 10 per cent of nearby early-type galaxies contain cores. Furthermore, we show that there is a genuine population of fast rotators with cores. We also show that core fast rotators are morphologically, kinematically and dynamically different from core slow rotators. The cores of fast rotators, however, could harbour black holes of similar masses to those in core slow rotators, but typically more massive than those found in core-less fast rotators. Cores of both fast and slow rotators are made of old stars and found in galaxies typically lacking molecular or atomic gas (with a few exceptions). Core-less galaxies, and especially core-less fast rotators, are under-luminous in the diffuse X-ray emission, but the presence of a core does not imply high X-ray luminosities. Additionally, we postulate (as many of these galaxies lack HST imaging) a possible population of core-less galaxies among slow rotators, which can not be explained as face-on discs, but comprise a genuine sub-population of slow rotators. These galaxies are typically less massive and flatter than core slow rotators, and show evidence for dynamical cold structures and exponential photometric components. Based on our findings, major non-dissipative (gas poor) mergers together with black hole binary evolution may not be the only path for formation of cores in early-type galaxies. We discuss possible processes for formation of cores and their subsequent preservation.

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Overview of the Near-IR S0 Galaxy Survey (NIRS0S)

Cited by 10 publications

References 79 publications

The ATLAS 3D project – XXIV. The intrinsic shape distribution of early-type galaxies

The ATLAS 3D project – XXIV. The intrinsic shape distribution of early-type galaxies

The ATLAS3D project – XVII. Linking photometric and kinematic signatures of stellar discs in early-type galaxies

The ATLAS3D Project – XXIII. Angular momentum and nuclear surface brightness profiles

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