The co-evolution of total density profiles and central dark matter fractions in simulated early-type galaxies

Remus, Rhea-Silvia; Dolag, K.; Naab, Thorsten; Burkert, Andreas; Hirschmann, Michaela; Hoffmann, T. L.; Johansson, Peter H.

doi:10.1093/mnras/stw2594

Cited by 106 publications

(146 citation statements)

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“…According to Remus et al (2017), the mass growth of massive galaxies can be explained by two stages: 1) High redshift in situ mass growth resulting in a dense stellar component in the center of the potential where the dark matter fraction is low, 2) dry merger events dominate the mass growth at lower redshift (with major mergers being rare) resulting in the build-up of a stellar envelope increasing the half-light radius and thus the dark matter fraction (similar to the interpretation above). 6.4.…”

Section: Stellar-to-dynamical Mass Evolutionmentioning

confidence: 99%

X-shooter Spectroscopy and HST Imaging of 15 Massive Quiescent Galaxies at z ≳ 2

Stockmann

Toft

Gallazzi

et al. 2019

ApJ

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We present a detailed analysis of a large sample of spectroscopically confirmed ultra-massive quiescent galaxies (log(M * /M ) ∼ 11.5) at z 2. This sample comprises 15 galaxies selected in the COSMOS and UDS fields by their bright K-band magnitudes and followed up with VLT/X-shooter spectroscopy and HST /WFC3 H F 160W imaging. These observations allow us to unambiguously confirm their redshifts ascertain their quiescent nature and stellar ages, and to reliably assess their internal kinematics and effective radii. We find that these galaxies are compact, consistent with the high mass end of the mass-size relation for quiescent galaxies at z = 2. Moreover, the distribution of the measured stellar velocity dispersions of the sample is consistent with the most massive local early-type galaxies from the MASSIVE Survey showing that evolution in these galaxies, is dominated by changes in size. The HST images reveal, as surprisingly high, that 40 % of the sample have tidal features suggestive of mergers and companions in close proximity, including three galaxies experiencing ongoing major mergers. The absence of velocity dispersion evolution from z = 2 to 0, coupled with a doubling of the stellar mass, with a factor of four size increase and the observed disturbed stellar morphologies support dry minor mergers as the primary drivers of the evolution of the massive quiescent galaxies over the last 10 billion years.

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Section: Stellar-to-dynamical Mass Evolutionmentioning

confidence: 99%

X-shooter Spectroscopy and HST Imaging of 15 Massive Quiescent Galaxies at z ≳ 2

Stockmann

Toft

Gallazzi

et al. 2019

ApJ

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“…Napolitano et al 2009;Deason et al 2012;Alabi et al 2016). However, recent models built on cosmological hydrodynamic simulations (Wu et al 2014;Remus et al 2017;Lovell et al 2018) notably predict shallower trends with mass for f DM at the fiducial 5r e . The range of expected values from the Magneticum simulations (Remus et al 2017) in particular is indicated by the dashed lines in Fig.…”

Section: Dark Matter Fraction Within 5r Ementioning

confidence: 97%

“…Contemporary cosmological hydrodynamic models (e.g. Remus et al 2017;Lovell et al 2018) predict that within 1r e the ratio of DM to total mass f DM ranges over ∼ 0.2 to 0.7 for large galaxies and is also a strong function of redshift. A higher in situ fraction of stellar mass should go along with lower f DM , while a larger fraction of dry merging (accretion) should extend the stellar mass profile and increase the inner f DM .…”

Section: Dark Matter Fraction Within 5r Ementioning

confidence: 99%

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Globular Cluster Systems and X-Ray Atmospheres in Galaxies*

Harris¹,

Babyk²,

Harris³

et al. 2019

ApJ

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We compare the empirical relationships between the mass of a galaxy's globular system M GCS , the gas mass in the hot X-ray atmosphere M X within a fiducial radius of 5r e , the total gravitational mass M grav within 5r e , and lastly the total halo mass M h calibrated from weak lensing. We use a sample of 45 early-type galaxies (ETGs) for which both GCS and X-ray data are available; all the galaxies in our sample are relatively high-mass ones with M h > 10 12 M . We find that M X ∝ M 1.0 h , similar to the previously known scaling relation M GCS ∝ M 1.0 h . Both components scale much more steeply than the more well known dependence of total stellar mass M ∝ M 0.3 h for luminous galaxies. These results strengthen previous suggestions that feedback had little effect on formation of the globular cluster system. The current data are also used to measure the relative mass fractions of baryonic matter and dark matter (DM) within 5r e . We find a strikingly uniform mean of f DM = 0.83 with few outliers and an rms scatter of ±0.07. This result is in good agreement with two recent suites of hydrodynamic galaxy formation models.

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“…In Figure 3 we show the derived dark matter fractions within 5 R e vs galaxy stellar mass from our analysis ) [7] and two sets of cosmological simulations. The simulations are with (Remus et al 2017) [8] and without (Wu et al 2014) [9] AGN feedback. The plot also shows a simple galaxy model based on galaxy scaling relations and an NFW dark matter halo.…”

Section: Dark Matter Contentmentioning

confidence: 99%

Assembly Pathways and the Growth of Massive Early-Type Galaxies

Forbes

2017

Galaxies

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Based on data from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, I present results on the assembly pathways, dark matter content and halo growth of massive early-type galaxies. Using galaxy starlight information we find that such galaxies had an early dissipative phase followed by a second phase of halo growth from largely minor mergers (and in rare cases major mergers). Thus our result fits in well with the two-phase scenario of galaxy formation. We also used globular cluster radial velocities to measure the enclosed mass within 5 effective radii. The resulting dark matter fractions reveal a few galaxies with very low dark matter fractions that are not captured in the latest cosmological models. Multiple solutions are possible, but none yet is convincing. Translating dark matter fractions into epochs of halo assembly, we show that low mass galaxies tend to grow via gas-rich accretion, while high mass galaxies grow via gas-poor mergers.Keywords: galaxies; formation; evolution; halos Assembly PathwaysThe SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey (Brodie et al. 2014) [1] is studying 25 nearby, massive (log stellar mass ∼11), early-type galaxies. The survey uses the DEIMOS multi-slit instrument on the Keck II telescope to obtain spectra of both the underlying starlight and surrounding globular clusters (GCs). The data have the advantage of reaching out to ∼3 R e (effective radii) for starlight and ∼10 R e for GCs. From this data, we can probe the dark matter content, assembly pathways and halo growth of these galaxies.A key aim of near-field cosmology is to determine the assembly history of an individual galaxy. The hydro-zoom cosmological simulations of Naab et al. (2014) [2] showed that the assembly histories of massive galaxies are preserved in the 2D kinematics of present day galaxies. In the Naab et al. simulations massive galaxies form in two phases-the first in-situ phase at high redshift results in a compact, massive object (a red nugget); the second phase after redshift 2 is dominated by accretion of ex-situ stars i.e., formed in external galaxies. In this picture low mass galaxies have a high in-situ formed fraction, whereas high mass galaxies are largely built by accretion. A schematic of this two-phase galaxy formation is given in Figure 1. Naab et al. used 3 kinematic diagnostics to classify galaxies into one of six assembly pathways. The SLUGGS starlight data provides similar diagnostics out to 3 R e . They are radial lambda (spin) profiles, 2D kinematic maps and higher order velocity moments h3 and h4 vs V/σ. Using these 3 diagnostics (see Figure 2 for examples) we have classified each galaxy into a Nabb et al. assembly class. We find the most common pathway (14/24) to be class A-these reveal disk-like kinematics with slowly rotating stellar halos whose mass growth is due to minor mergers. Three galaxies are classified as class E which show disturbed kinematics, including rolling, double sigma profile and a decoupled core. Galaxies with high accretion ...

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The co-evolution of total density profiles and central dark matter fractions in simulated early-type galaxies

Cited by 106 publications

References 100 publications

X-shooter Spectroscopy and HST Imaging of 15 Massive Quiescent Galaxies at z ≳ 2

X-shooter Spectroscopy and HST Imaging of 15 Massive Quiescent Galaxies at z ≳ 2

Globular Cluster Systems and X-Ray Atmospheres in Galaxies*

Assembly Pathways and the Growth of Massive Early-Type Galaxies

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