16 research outputs found
On the coherent rotation of diffuse matter in numerical simulations of galaxy clusters
We present a study on the coherent rotation of the intracluster medium and
dark matter components of simulated galaxy clusters extracted from a
volume-limited sample of the MUSIC project. The set is re-simulated with three
different recipes for the gas physics: non-radiative, radiative
without AGN feedback, and radiative with AGN feedback. Our analysis is
based on the 146 most massive clusters identified as relaxed, 57 per cent of
the total sample. We classify these objects as rotating and non-rotating
according to the gas spin parameter, a quantity that can be related to cluster
observations. We find that 4 per cent of the relaxed sample is rotating
according to our criterion. By looking at the radial profiles of their specific
angular momentum vector, we find that the solid body model is not a suitable
description of rotational motions. The radial profiles of the velocity of the
dark matter show a prevalence of the random velocity dispersion. Instead, the
intracluster medium profiles are characterized by a comparable contribution
from the tangential velocity and the dispersion. In general, the dark matter
component dominates the dynamics of the clusters, as suggested by the
correlation between its angular momentum and the gas one, and by the lack of
relevant differences among the three sets of simulations.Comment: 12 pages, updated to match the MNRAS versio
nIFTy galaxy cluster simulations – II. Radiative models
We have simulated the formation of a massive galaxy cluster (M = 1.110) in a CDM universe using
10 different codes (RAMSES, 2 incarnations of AREPO and 7 of GADGET), modeling
hydrodynamics with full radiative subgrid physics. These codes include
Smoothed-Particle Hydrodynamics (SPH), spanning traditional and advanced SPH
schemes, adaptive mesh and moving mesh codes. Our goal is to study the
consistency between simulated clusters modeled with different radiative
physical implementations - such as cooling, star formation and AGN feedback. We
compare images of the cluster at , global properties such as mass, and
radial profiles of various dynamical and thermodynamical quantities. We find
that, with respect to non-radiative simulations, dark matter is more centrally
concentrated, the extent not simply depending on the presence/absence of AGN
feedback. The scatter in global quantities is substantially higher than for
non-radiative runs. Intriguingly, adding radiative physics seems to have washed
away the marked code-based differences present in the entropy profile seen for
non-radiative simulations in Sembolini et al. (2015): radiative physics +
classic SPH can produce entropy cores. Furthermore, the inclusion/absence of
AGN feedback is not the dividing line -as in the case of describing the stellar
content- for whether a code produces an unrealistic temperature inversion and a
falling central entropy profile. However, AGN feedback does strongly affect the
overall stellar distribution, limiting the effect of overcooling and reducing
sensibly the stellar fraction.Comment: 20 pages, 13 figures, submitted to MNRA
The MUSIC of Galaxy Clusters I: Baryon properties and Scaling Relations of the thermal Sunyaev-Zel'dovich Effect
We introduce the Marenostrum-MultiDark SImulations of galaxy Clusters (MUSIC)
Dataset, one of the largest sample of hydrodynamically simulated galaxy
clusters with more than 500 clusters and 2000 groups. The objects have been
selected from two large N-body simulations and have been resimulated at high
resolution using SPH together with relevant physical processes (cooling, UV
photoionization, star formation and different feedback processes). We focus on
the analysis of the baryon content (gas and star) of clusters in the MUSIC
dataset both as a function of aperture radius and redshift. The results from
our simulations are compared with the most recent observational estimates of
the gas fraction in galaxy clusters at different overdensity radii. When the
effects of cooling and stellar feedbacks are included, the MUSIC clusters show
a good agreement with the most recent observed gas fractions quoted in the
literature. A clear dependence of the gas fractions with the total cluster mass
is also evident. The impact of the aperture radius choice, when comparing
integrated quantities at different redshifts, is tested: the standard
definition of radius at a fixed overdensity with respect to critical density is
compared with a definition based on the redshift dependent overdensity with
respect to background density. We also present a detailed analysis of the
scaling relations of the thermal SZ (Sunyaev Zel'dovich) Effect derived from
MUSIC clusters. The integrated SZ brightness, Y, is related to the cluster
total mass, M, as well as, the M-Y counterpart, more suitable for observational
applications. Both laws are consistent with predictions from the self-similar
model, showing a very low scatter. The effects of the gas fraction on the Y-M
scaling and the presence of a possible redshift dependence on the Y-M scaling
relation are also explored.Comment: 22 pages, 25 figures, accepted for pubblication by MNRA
nIFTy galaxy cluster simulations - IV. Quantifying the influence of baryons on halo properties
Building on the initial results of the nIFTy simulated galaxy cluster comparison, we compare
and contrast the impact of baryonic physics with a single massive galaxy cluster, run with 11
state-of-the-art codes, spanning adaptive mesh, moving mesh, classic and modern smoothed
particle hydrodynamics (SPH) approaches. For each code represented we have a dark-matteronly
(DM) and non-radiative (NR) version of the cluster, as well as a full physics (FP) version
for a subset of the codes. We compare both radial mass and kinematic profiles, as well as
global measures of the cluster (e.g. concentration, spin, shape), in the NR and FP runs with
that in the DM runs. Our analysis reveals good consistency (<≈
20 per cent) between global
properties of the cluster predicted by different codes when integrated quantities are measured
within the virial radius R200. However, we see larger differences for quantities within R2500,
especially in the FP runs. The radial profiles reveal a diversity, especially in the cluster centre,
between the NR runs, which can be understood straightforwardly from the division of codes
into classic SPH and non-classic SPH (including the modern SPH, adaptive and moving mesh
codes); and between the FP runs, which can also be understood broadly from the division
of codes into those that include active galactic nucleus feedback and those that do not. The
variation with respect to the median is much larger in the FP runs with different baryonic
physics prescriptions than in the NR runs with different hydrodynamics solvers
nIFTy galaxy cluster simulations – I. Dark matter and non-radiative models
We have simulated the formation of a galaxy cluster in a É… cold dark matter universe using 13 different codes modelling only gravity and non-radiative hydrodynamics (RAMSES, ART, AREPO, HYDRA and nine incarnations of GADGET). This range of codes includes particle-based, moving and fixed mesh codes as well as both Eulerian and Lagrangian fluid schemes. The various GADGET implementations span classic and modern smoothed particle hydrodynamics (SPH) schemes. The goal of this comparison is to assess the reliability of cosmological hydrodynamical simulations of clusters in the simplest astrophysically relevant case, that in which the gas is assumed to be non-radiative. We compare images of the cluster at z = 0, global properties such as mass and radial profiles of various dynamical and thermodynamical quantities. The underlying gravitational framework can be aligned very accurately for all the codes allowing a detailed investigation of the differences that develop due to the various gas physics implementations employed. As expected, the mesh-based codes RAMSES, ART and AREPO form extended entropy cores in the gas with rising central gas temperatures. Those codes employing classic SPH schemes show falling entropy profiles all the way into the very centre with correspondingly rising density profiles and central temperature inversions. We show that methods with modern SPH schemes that allow entropy mixing span the range between these two extremes and the latest SPH variants produce gas entropy profiles that are essentially indistinguishable from those obtained with grid-based methods
Baryon and Sunyaev-Zel’dovich Effect properties of MareNostrum and MultiDark Simulated Clusters (MUSIC)
We report the first results of the MUSIC project. It consists of two data sets of resimulates clusters extracted from two large dark matter only simulations: Marenostrum Universe and Multidark. In total, the MUSIC contains more than 400 clusters resimulated with high resolution both with radiative and non-radiative physics
included. Here we present the first results on the properties of the baryon content and the Sunyaev Zeldovich scaling relations
Kinetic Sunyaev–Zel’dovich effect in rotating galaxy clusters from MUSIC simulations
The masses of galaxy clusters are a key tool to constrain cosmology through
the physics of large-scale structure formation and accretion. Mass estimates
based on X-ray and Sunyaev--Zel'dovich measurements have been found to be
affected by the contribution of non-thermal pressure components, due e.g. to
kinetic gas energy. The characterization of possible ordered motions (e.g.
rotation) of the intra-cluster medium could be important to recover cluster
masses accurately. We update the study of gas rotation in clusters through the
maps of the kinetic Sunyaev--Zel'dovich effect, using a large sample of massive
synthetic galaxy clusters (M at
) from MUSIC high-resolution simulations. We select few relaxed objects
showing peculiar rotational features, as outlined in a companion work. To
verify whether it is possible to reconstruct the expected radial profile of the
rotational velocity, we fit the maps to a theoretical model accounting for a
specific rotational law, referred as the vp2b model. We find that our procedure
allows to recover the parameters describing the gas rotational velocity profile
within two standard deviations, both with and without accounting for the bulk
velocity of the cluster. The amplitude of the temperature distortion produced
by the rotation is consistent with theoretical estimates found in the
literature, and it is of the order of 23 per cent of the maximum signal
produced by the cluster bulk motion. We also recover the bulk velocity
projected on the line of sight consistently with the simulation true value