Projected Central Dark Matter Fractions and Densities in Massive Early-Type Galaxies From the Sloan Digital Sky Survey

Grillo, C.

doi:10.1088/0004-637x/722/1/779

Cited by 45 publications

(67 citation statements)

References 94 publications

(134 reference statements)

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“…The clear positive correlation between f dm (R R eff ) [or f dm (R 0.5 R eff )] and lg R eff may purely be an aperture effect: the dark matter fraction drops with decreasing radius as baryons dominate more and more towards the galactic centre (also see Grillo 2010;and Fig. 3 of Xu et al 2016).…”

Section: Projected Central Dark Matter Fractionsmentioning

confidence: 96%

The inner structure of early-type galaxies in the Illustris simulation

Springel

Sluse³

et al. 2017

Monthly Notices of the Royal Astronomical Society

139

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Early-type galaxies provide unique tests for the predictions of the cold dark matter cosmology and the baryonic physics assumptions entering models for galaxy formation. In this work, we use the Illustris simulation to study correlations of three main properties of early-type galaxies, namely, the stellar orbital anisotropies, the central dark matter fractions and the central radial density slopes, as well as their redshift evolution since z = 1.0. We find that lower-mass galaxies or galaxies at higher redshift tend to be bluer in rest-frame colour, have higher central gas fractions, and feature more tangentially anisotropic orbits and steeper central density slopes than their higher-mass or lowerredshift counterparts, respectively. The projected central dark matter fraction within the effective radius shows a very mild mass dependence but positively correlates with galaxy effective radii due to the aperture effect. The central density slopes obtained by combining strong lensing measurements with single aperture kinematics are found to differ from the true density slopes. We identify systematic biases in this measurement to be due to two common modelling assumptions, isotropic stellar orbital distributions and power-law density profiles. We also compare the properties of early-type galaxies in Illustris to those from existing galaxy and strong lensing surveys, we find in general broad agreement but also some tension, which poses a potential challenge to the stellar formation and feedback models adopted by the simulation.

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Section: Projected Central Dark Matter Fractionsmentioning

confidence: 96%

The inner structure of early-type galaxies in the Illustris simulation

Springel

Sluse³

et al. 2017

Monthly Notices of the Royal Astronomical Society

139

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show abstract

“…So far, most of the DM studies were limited to low-redshift samples, and only recently systematic analysis of high redshift samples have been started. In some cases the datasets are restricted to small samples and small redshift windows to evaluate the dependence of the galaxy DM content on redshift, as in the case of gravitational lenses (Auger et al 2009, 2010, Tortora et al 2010bSonnenfeld et al 2013). The first studies have given contrasting results (Faure et al 2011;Ruff et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The last 6 Gyr of dark matter assembly in massive galaxies from the Kilo Degree Survey

Tortora

Napolitano

Roy

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We study the dark matter (DM) assembly in the central regions of massive early-type galaxies up to z ∼ 0.65. We use a sample of ∼ 3800 massive (log M /M > 11.2) galaxies with photometry and structural parameters from 156 sq. deg. of the Kilo Degree Survey, and spectroscopic redshifts and velocity dispersions from SDSS. We obtain central total-to-stellar mass ratios, M dyn /M , and DM fractions, by determining dynamical masses, M dyn , from Jeans modelling of SDSS aperture velocity dispersions and stellar masses, M , from KiDS galaxy colours. We first show how the central DM fraction correlates with structural parameters, mass and density proxies, and demonstrate that most of the local correlations are still observed up to z ∼ 0.65; at fixed M , local galaxies have larger DM fraction, on average, than their counterparts at larger redshift. We also interpret these trends with a non universal Initial Mass Function (IMF), finding a strong evolution with redshift, which contrast independent observations and is at odds with the effect of galaxy mergers. For a fixed IMF, the galaxy assembly can be explained, realistically, by mass and size accretion, which can be physically achieved by a series of minor mergers. We reproduce both the R e -M and M dyn /M -M evolution with stellar and dark mass changing at a different rate. This result suggests that the main progenitor galaxy is merging with less massive systems, characterized by a smaller M dyn /M , consistently with results from halo abundance matching.

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“…Estimates of ϒ are also derived using dynamics or gravitational lensing. Comparison of the independent results then yields a revised IMF (e.g., Cappellari et al 2006Cappellari et al , 2012aCappellari et al , 2012bFerreras et al 2008;Tortora et al 2009Tortora et al , 2010Tortora et al , 2012Grillo & Gobat 2010;Grillo 2010;Treu et al 2010;Napolitano et al 2010Napolitano et al , 2011Auger et al 2010; Thomas et al 2011;Spiniello et al 2011;Dutton et al 2012aDutton et al , 2012bSonnenfeld et al 2012;Wegner et al 2012).…”

Section: Introductionmentioning

confidence: 99%

An Inventory of the Stellar Initial Mass Function in Early-Type Galaxies

Tortora

Romanowsky

Napolitano

2013

ApJ

105

158

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Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar population synthesis (SPS) and Jeans dynamical analyses of data on ∼4500 early-type galaxies (ETGs) from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, δ IMF , correlated against the central stellar velocity dispersion, σ . We find a strong correlation between δ IMF and σ , for a wide set of dark matter (DM) model profiles. These results are robust if a uniform halo response to baryons is adopted across the sample. The overall normalization of δ IMF and the detailed DM profile are less certain, but the data are consistent with standard cold DM halos and a central DM fraction that is roughly constant with σ . For a variety of related studies in the literature, using SPS, dynamics, and gravitational lensing, similar results are found. Studies based solely on spectroscopic line diagnostics agree on a Salpeter-like IMF at high σ but differ at low σ . Overall, we find that multiple independent lines of evidence appear to be converging on a systematic variation in the IMF, such that high-σ ETGs have an excess of low-mass stars relative to spirals and low-σ ETGs. Robust verification of super-Salpeter IMFs in the highest-σ galaxies will require additional scrutiny of scatter and systematic uncertainties. The implications for the distribution of DM are still inconclusive.

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Projected Central Dark Matter Fractions and Densities in Massive Early-Type Galaxies From the Sloan Digital Sky Survey

Cited by 45 publications

References 94 publications

The inner structure of early-type galaxies in the Illustris simulation

The inner structure of early-type galaxies in the Illustris simulation

The last 6 Gyr of dark matter assembly in massive galaxies from the Kilo Degree Survey

An Inventory of the Stellar Initial Mass Function in Early-Type Galaxies

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