scholarly journals The assembly of the Virgo cluster, traced by its galaxy haloes

2019 ◽  
Vol 488 (1) ◽  
pp. 1111-1126 ◽  
Author(s):  
James E Taylor ◽  
Jihye Shin ◽  
Nathalie N-Q Ouellette ◽  
Stéphane Courteau
Keyword(s):  
Dark Matter ◽  
Cluster Formation ◽  
Virgo Cluster ◽  
Scaling Relations ◽  
Density Profiles ◽  
Large Samples ◽  
Dark Matter Mass ◽  
Theoretical Predictions ◽  
History Of ◽  
Kinematic Studies

ABSTRACT Kinematic studies have produced accurate measurements of the total dark matter mass and mean dark matter density within the optical extent of galaxies for large samples of objects. Here we consider theoretical predictions for the latter quantity, $\bar{\rho }_{\rm dm}$, measured within the isophotal radius R23.5, for isolated haloes with universal density profiles. Through a combination of empirical scaling relations, we show that $\bar{\rho }_{\rm dm}$ is expected to depend weakly on halo mass and strongly on redshift. When galaxy haloes fall into larger groups or clusters, they become tidally stripped, reducing their total dark matter mass, but this process is expected to preserve central density until an object is close to disruption. We confirm this with collisonless simulations of cluster formation, finding that subhaloes have values of $\bar{\rho }_{\rm dm}$ close to the analytic predictions. This suggests that $\bar{\rho }_{\rm dm}$ may be a useful indicator of infall redshift on to the cluster. We test this hypothesis with data from the SHIVir survey, which covers a reasonable fraction of the Virgo cluster. We find that galaxies with high $\bar{\rho }_{\rm dm}$ do indeed trace the densest regions of the cluster, with a few notable exceptions. Samples selected by environment have higher densities at a significance of 3.5–4σ, while samples selected by density are more clustered at 3–3.5σ significance. We conclude that halo density can be a powerful tracer of the assembly history of clusters and their member galaxies.

Cosmic structure

2014 ◽  
Vol 23 (10) ◽  
pp. 1430021
Author(s):  
Marc Davis
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Initial Conditions ◽  
Cluster Formation ◽  
Acoustic Oscillations ◽  
Highly Nonlinear ◽  
History Of

The history of cosmic structure goes back to the time of Einstein's youth, although few scientists actually thought of the problem of galaxy and cluster formation. The data and ideas were collected slowly as astronomers slowly realized the nature of the problem of large-scale structure. This paper will review several of the key episodes in the history of the field. Starting with the discovery of dark matter in the 30s, the CMBR discovery in the 1960s to the idea of an early episode of inflation in the 1980s, the field has had an acceleration of discovery. In the 80s it was realized that the initial conditions of the universe were specified by the cold dark matter (CDM). Now initial conditions for the formation of structure could be specified for any type of dark matter. With the advent of computing resources, highly nonlinear phases of galaxy formation could be simulated and scientists could ask whether cold dark matter was the correct theory, even on the scale of dwarf spheroidal galaxies, or do the properties of the dwarfs require a different type of dark matter? In an idiosyncratic list, we review several of the key events of the history of cosmic structure, including the first measurements of ξ(r), then the remarkable success of Λ CDM explanations of the large-scale universe. We next turn to velocity fields, the large-scale flow problem, a field which was so promising 20 years ago, and to the baryon acoustic oscillations, a field of remarkable promise today. We review the problem of dwarf galaxies and Lyman-α absorption systems, asking whether the evidence is pointing toward a major switch in our understanding of the nature of dark matter. Finally, we discuss flux anomalies in multiply-lensed systems, which set constraints on the number of dwarf galaxies associated with the lensing galaxy, a topic that is now very interesting since simulations have indicated there should be hundreds of dwarfs orbiting the Milky Way, rather than the 10 that are known. It is quite remarkable that many of the today's results are dependent on techniques first used by Einstein.

scholarly journals Scaling relations of fuzzy dark matter haloes – I. Individual systems in their cosmological environment

2020 ◽  
Vol 501 (1) ◽  
pp. 1539-1556
Author(s):  
Matteo Nori ◽  
Marco Baldi
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dark Matter Particle ◽  
Small Scale ◽  
Scaling Relations ◽  
Linear Evolution ◽  
Cosmological Context ◽  
History Of ◽  
The Individual ◽  
Isolated Systems

ABSTRACT Dark matter models involving a very light bosonic particle, generally known as fuzzy dark matter (FDM), have been recently attracting great interest in the cosmology community, as their wave-like phenomenology would simultaneously explain the long-standing misdetection of a dark matter particle and help easing the small-scale issues related to the standard cold dark matter (CDM) scenario. With this work, we initiate a series of papers aiming at investigating the evolution of FDM structures in a cosmological framework performed with our N-body code ax-gadget, detailing for the first time in the literature how the actual scaling relations between solitonic cores and host haloes properties are significantly affected by the dynamical state, morphology, and merger history of the individual systems. In particular, in this first paper we confirm the ability of ax-gadget to correctly reproduce the typical FDM solitonic core and we employ it to study the non-linear evolution of eight FDM haloes in their cosmological context through the zoom-in simulation approach. We find that the scaling relations identified in previous works for isolated systems are generally modified for haloes evolving in a realistic cosmological environment, and appear to be valid only as a limit for the most relaxed and spherically symmetric systems.

scholarly journals Structure and kinematics of the Virgo cluster of galaxies

2020 ◽  
Vol 635 ◽  
pp. A135 ◽  
Author(s):  
Olga G. Kashibadze ◽  
Igor D. Karachentsev ◽  
Valentina E. Karachentseva
Keyword(s):  
Dark Matter ◽  
Radial Velocity ◽  
Virgo Cluster ◽  
Radial Velocities ◽  
Cluster Core ◽  
Number Density ◽  
Density Profiles ◽  
Cluster Of Galaxies ◽  
Virial Mass ◽  
Mass Estimate

Aims. This work considers the Virgo cluster of galaxies, focusing on its structure, kinematics, and morphological landscape. Our principal aim is to estimate the virial mass of the cluster. For this purpose, we present a sample of 1537 galaxies with radial velocities VLG <  2600 km s−1 situated within a region of ΔSGL = 30° and ΔSGB = 20° around M 87. About half of the galaxies have distance estimates. Methods. We selected 398 galaxies with distances in a (17 ± 5) Mpc range. Based on their 1D and 2D number-density profiles and their radial velocity dispersions, we made an estimate for the virial mass of the Virgo cluster. Results. We identify the infall of galaxies towards the Virgo cluster core along the Virgo Southern Extension filament. From a 1D profile of the cluster, we obtain the virial mass estimate of (6.3 ± 0.9)×1014 M⊙, which is in tight agreement with its mass estimate via the external infall pattern of galaxies. Conclusions. We conclude that the Virgo cluster outskirts between the virial radius and the zero-velocity radius do not contain significant amounts of dark matter beyond the virial radius.

scholarly journals Constraining the inner density slope of massive galaxy clusters

2020 ◽  
Vol 496 (4) ◽  
pp. 4717-4733 ◽  
Author(s):  
Qiuhan He ◽  
Hongyu Li ◽  
Ran Li ◽  
Carlos S Frenk ◽  
Matthieu Schaller ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Matter Density ◽  
Stellar Kinematics ◽  
Density Profiles ◽  
Mass Distributions ◽  
Dark Matter Density ◽  
Dark Matter Mass ◽  
Massive Galaxy

ABSTRACT We determine the inner density profiles of massive galaxy clusters (M200 &gt; 5 × 1014 M⊙) in the Cluster-EAGLE (C-EAGLE) hydrodynamic simulations, and investigate whether the dark matter density profiles can be correctly estimated from a combination of mock stellar kinematical and gravitational lensing data. From fitting mock stellar kinematics and lensing data generated from the simulations, we find that the inner density slopes of both the total and the dark matter mass distributions can be inferred reasonably well. We compare the density slopes of C-EAGLE clusters with those derived by Newman et al. for seven massive galaxy clusters in the local Universe. We find that the asymptotic best-fitting inner slopes of ‘generalized’ Navarro–Frenk–White (gNFW) profiles, γgNFW, of the dark matter haloes of the C-EAGLE clusters are significantly steeper than those inferred by Newman et al. However, the mean mass-weighted dark matter density slopes of the simulated clusters are in good agreement with the Newman et al. estimates. We also find that the estimate of γgNFW is very sensitive to the constraints from weak lensing measurements in the outer parts of the cluster and a bias can lead to an underestimate of γgNFW.

scholarly journals Constraints on the mass–concentration relation of cold dark matter haloes with 11 strong gravitational lenses

2019 ◽  
Vol 492 (1) ◽  
pp. L12-L16 ◽  
Author(s):  
Daniel Gilman ◽  
Xiaolong Du ◽  
Andrew Benson ◽  
Simon Birrer ◽  
Anna Nierenberg ◽  
...  
Keyword(s):  
Dark Matter ◽  
Mass Concentration ◽  
Cold Dark Matter ◽  
Finite Size ◽  
Mass Range ◽  
Nuisance Parameters ◽  
Gravitational Lenses ◽  
Matter Power Spectrum ◽  
Theoretical Predictions ◽  
History Of

ABSTRACT The mass–concentration relation of dark matter haloes reflects the assembly history of objects in hierarchical structure formation scenarios and depends on fundamental quantities in cosmology such as the slope of the primordial matter power spectrum. This relation is unconstrained by observations on sub-galactic scales. We derive the first measurement of the mass–concentration relation using the image positions and flux ratios from 11 quadruple-image strong gravitational lenses (quads) in the mass range $10^{6}\!-\!10^{10} {\, \mathrm{M}_{\odot }}$, assuming cold dark matter. We model both subhaloes and line-of-sight haloes, finite-size background sources, and marginalize over nuisance parameters describing the lens macromodel. We also marginalize over the logarithmic slope and redshift evolution of the mass–concentration relation, using flat priors that encompass the range of theoretical uncertainty in the literature. At z = 0, we constrain the concentration of $10^{8} \, \mathrm{M}_{\odot }$ haloes $c=12_{-5}^{+6}$ at $68 {{\ \rm per\ cent}}$ CI, and $c=12_{-9}^{+15}$ at $95 {{\ \rm per\ cent}}$ CI. For a $10^{7} {\, \mathrm{M}_{\odot }}$ halo, we obtain $68 {{\ \rm per\ cent}}$ ($95 {{\ \rm per\ cent}}$) constraints $c=15_{-8}^{+9}$ ($c=15_{-11}^{+18}$), while for $10^{9} \, \mathrm{M}_{\odot }$ haloes $c=10_{-4}^{+7}$ ($c=10_{-7}^{+14}$). These results are consistent with the theoretical predictions from mass–concentration relations in the literature and establish strong lensing by galaxies as a powerful probe of halo concentrations on sub-galactic scales across cosmological distance.

scholarly journals Effects of initial density profiles on massive star cluster formation in giant molecular clouds

2021 ◽  
Author(s):  
Yingtian Chen ◽  
Hui Li ◽  
Mark Vogelsberger
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Molecular Clouds ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Initial Density ◽  
Giant Molecular Clouds ◽  
Density Profiles ◽  
Stellar Feedback ◽  
Gas Accretion

Abstract We perform a suite of hydrodynamic simulations to investigate how initial density profiles of giant molecular clouds (GMCs) affect their subsequent evolution. We find that the star formation duration and integrated star formation efficiency of the whole clouds are not sensitive to the choice of different profiles but are mainly controlled by the interplay between gravitational collapse and stellar feedback. Despite this similarity, GMCs with different profiles show dramatically different modes of star formation. For shallower profiles, GMCs first fragment into many self-gravitation cores and form sub-clusters that distributed throughout the entire clouds. These sub-clusters are later assembled ‘hierarchically’ to central clusters. In contrast, for steeper profiles, a massive cluster is quickly formed at the center of the cloud and then gradually grows its mass via gas accretion. Consequently, central clusters that emerged from clouds with shallower profiles are less massive and show less rotation than those with the steeper profiles. This is because 1) a significant fraction of mass and angular momentum in shallower profiles is stored in the orbital motion of the sub-clusters that are not able to merge into the central clusters 2) frequent hierarchical mergers in the shallower profiles lead to further losses of mass and angular momentum via violent relaxation and tidal disruption. Encouragingly, the degree of cluster rotations in steeper profiles is consistent with recent observations of young and intermediate-age clusters. We speculate that rotating globular clusters are likely formed via an ‘accretion’ mode from centrally-concentrated clouds in the early Universe.

scholarly journals The merger-driven evolution of massive early-type galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 62-66
Author(s):  
Carlo Cannarozzo ◽  
Carlo Nipoti ◽  
Alessandro Sonnenfeld ◽  
Alexie Leauthaud ◽  
Song Huang ◽  
...  
Keyword(s):  
Mass Velocity ◽  
Selection Criteria ◽  
Velocity Dispersion ◽  
Ex Situ ◽  
Scaling Relations ◽  
Early Type ◽  
History Of ◽  
Kinematic Properties ◽  
Shed Light

AbstractThe evolution of the structural and kinematic properties of early-type galaxies (ETGs), their scaling relations, as well as their stellar metallicity and age contain precious information on the assembly history of these systems. We present results on the evolution of the stellar mass-velocity dispersion relation of ETGs, focusing in particular on the effects of some selection criteria used to define ETGs. We also try to shed light on the role that in-situ and ex-situ stellar populations have in massive ETGs, providing a possible explanation of the observed metallicity distributions.

scholarly journals Evidence for multiple introductions of an invasive wild bee species currently under rapid range expansion in Europe

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Julia Lanner ◽  
Fabian Gstöttenmayer ◽  
Manuel Curto ◽  
Benoît Geslin ◽  
Katharina Huchler ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Invasion History ◽  
European Continent ◽  
Multiple Introductions ◽  
Wild Bee ◽  
Invasion Stage ◽  
Middle Europe ◽  
History Of ◽  
Genetic Clusters ◽  
Colonization Dynamics

Abstract Background Invasive species are increasingly driving biodiversity decline, and knowledge of colonization dynamics, including both drivers and dispersal modes, are important to prevent future invasions. The bee species Megachile sculpturalis (Hymenoptera: Megachilidae), native to East-Asia, was first recognized in Southeast-France in 2008, and has since spread throughout much of Europe. The spread is very fast, and colonization may result from multiple fronts. Result To track the history of this invasion, codominant markers were genotyped using Illumina sequencing and the invasion history and degree of connectivity between populations across the European invasion axis were investigated. Distinctive genetic clusters were detected with east–west differentiations in Middle-Europe. Conclusion We hypothesize that the observed cluster formation resulted from multiple, independent introductions of the species to the European continent. This study draws a first picture of an early invasion stage of this wild bee and forms a foundation for further investigations, including studies of the species in their native Asian range and in the invaded range in North America.

scholarly journals Displaced new physics at colliders and the early universe before its first second

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Lorenzo Calibbi ◽  
Francesco D’Eramo ◽  
Sam Junius ◽  
Laura Lopez-Honorez ◽  
Alberto Mariotti
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Upper Bound ◽  
New Physics ◽  
Early History ◽  
Relic Density ◽  
History Of ◽  
Indirect Information ◽  
The Universe

Abstract Displaced vertices at colliders, arising from the production and decay of long-lived particles, probe dark matter candidates produced via freeze-in. If one assumes a standard cosmological history, these decays happen inside the detector only if the dark matter is very light because of the relic density constraint. Here, we argue how displaced events could very well point to freeze-in within a non-standard early universe history. Focusing on the cosmology of inflationary reheating, we explore the interplay between the reheating temperature and collider signatures for minimal freeze-in scenarios. Observing displaced events at the LHC would allow to set an upper bound on the reheating temperature and, in general, to gather indirect information on the early history of the universe.

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