42 research outputs found
The effect of massive neutrinos on the Sunyaev-Zeldovich and X-ray observables of galaxy clusters
Massive neutrinos are expected to influence the formation of the large-scale
structure of the Universe, depending on the value of their total mass, . In particular Planck data indicate that a non-zero may
help to reconcile CMB data with Sunyaev-Zel'dovich (SZ) cluster surveys. In
order to study the impact of neutrinos on the SZ and X-ray cluster properties
we run a set of six very large cosmological simulations (8 Gpc
comoving volume) that include a massive neutrino particle component: we
consider the values of = (0, 0.17, 0.34) eV in two cosmological
scenarios to test possible degeneracies. Using the halo catalogues extracted
from their outputs we produce 50 mock light-cones and, assuming suitable
scaling relations, we determine how massive neutrinos affect SZ and X-ray
cluster counts, the -parameter and its power spectrum. We provide forecasts
for the South Pole Telescope (SPT) and eROSITA cluster surveys, showing that
the number of expected detections is reduced by 40 per cent when assuming
=0.34 eV with respect to a model with massless neutrinos.
However the degeneracy with and is strong, in particular
for X-ray data, requiring the use of additional probes to break it. The
-parameter properties are also highly influenced by the neutrino mass
fraction, , with , considering the cluster
component only, and the normalization of the SZ power spectrum is proportional
to . Comparing our findings with SPT and Atacama Cosmology
Telescope measurements at = 3000 indicates that, when Planck
cosmological parameters are assumed, a value of eV is
required to fit with the data.Comment: 13 pages, 10 figures, 3 tables. Accepted for publication by MNRAS.
Substantial revisions after reviewer's comment
Constraints on and from the potential-based cluster temperature function
The abundance of galaxy clusters is in principle a powerful tool to constrain
cosmological parameters, especially and , due to
the exponential dependence in the high-mass regime. While the best observables
are the X-ray temperature and luminosity, the abundance of galaxy clusters,
however, is conventionally predicted as a function of mass. Hence, the
intrinsic scatter and the uncertainties in the scaling relations between mass
and either temperature or luminosity lower the reliability of galaxy clusters
to constrain cosmological parameters. In this article, we further refine the
X-ray temperature function for galaxy clusters by Angrick et al., which is
based on the statistics of perturbations in the cosmic gravitational potential
and proposed to replace the classical mass-based temperature function, by
including a refined analytic merger model and compare the theoretical
prediction to results from a cosmological hydrodynamical simulation. Although
we find already a good agreement if we compare with a cluster temperature
function based on the mass-weighted temperature, including a redshift-dependent
scaling between mass-based and spectroscopic temperature yields even better
agreement between theoretical model and numerical results. As a proof of
concept, incorporating this additional scaling in our model, we constrain the
cosmological parameters and from an X-ray sample
of galaxy clusters and tentatively find agreement with the recent cosmic
microwave background based results from the Planck mission at 1-level.Comment: 10 pages, 5 figures, 2 tables; accepted by MNRAS; some typos
correcte
AMICO: optimised detection of galaxy clusters in photometric surveys
We present AMICO (Adaptive Matched Identifier of Clustered Objects), a new
algorithm for the detection of galaxy clusters in photometric surveys. AMICO is
based on the Optimal Filtering technique, which allows to maximise the
signal-to-noise ratio of the clusters. In this work we focus on the new
iterative approach to the extraction of cluster candidates from the map
produced by the filter. In particular, we provide a definition of membership
probability for the galaxies close to any cluster candidate, which allows us to
remove its imprint from the map, allowing the detection of smaller structures.
As demonstrated in our tests, this method allows the deblending of close-by and
aligned structures in more than of the cases for objects at radial
distance equal to or redshift distance equal to , being the typical uncertainty of photometric redshifts.
Running AMICO on mocks derived from N-body simulations and semi-analytical
modelling of the galaxy evolution, we obtain a consistent mass-amplitude
relation through the redshift range , with a logarithmic slope
and a logarithmic scatter . The fraction of false
detections is steeply decreasing with S/N, and negligible at S/N > 5.Comment: 18 pages, accepted for publication in MNRA
AMICO galaxy clusters in KiDS-DR3: sample properties and selection function
We present the first catalogue of galaxy cluster candidates derived from the
third data release of the Kilo Degree Survey (KiDS-DR3). The sample of clusters
has been produced using the Adaptive Matched Identifier of Clustered Objects
(AMICO) algorithm. In this analysis AMICO takes advantage of the luminosity and
spatial distribution of galaxies only, not considering colours. In this way, we
prevent any selection effect related to the presence or absence of the
red-sequence in the clusters. The catalogue contains 7988 candidate galaxy
clusters in the redshift range 0.13.5 with a purity
approaching 95% over the entire redshift range. In addition to the catalogue of
galaxy clusters we also provide a catalogue of galaxies with their
probabilistic association to galaxy clusters. We quantify the sample purity,
completeness and the uncertainties of the detection properties, such as
richness, redshift, and position, by means of mock galaxy catalogues derived
directly from the data. This preserves their statistical properties including
photo-z uncertainties, unknown absorption across the survey, missing data,
spatial correlation of galaxies and galaxy clusters. Being based on the real
data, such mock catalogues do not have to rely on the assumptions on which
numerical simulations and semi-analytic models are based on. This paper is the
first of a series of papers in which we discuss the details and physical
properties of the sample presented in this work.Comment: 16 pages, 14 figures, 3 tables, submitted to MNRA
AMICO galaxy clusters in KiDS-DR3: weak-lensing mass calibration
We present the mass calibration for galaxy clusters detected with the AMICO
code in KiDS DR3 data. The cluster sample comprises 7000 objects and
covers the redshift range 0.1 < < 0.6. We perform a weak lensing stacked
analysis by binning the clusters according to redshift and two different mass
proxies provided by AMICO, namely the amplitude (measure of galaxy
abundance through an optimal filter) and the richness (sum of
membership probabilities in a consistent radial and magnitude range across
redshift). For each bin, we model the data as a truncated NFW profile plus a
2-halo term, taking into account uncertainties related to concentration and
miscentring. From the retrieved estimates of the mean halo masses, we construct
the - and the - relations. The relations extend
over more than one order of magnitude in mass, down to at = 0.2 (0.5), with small evolution in redshift.
The logarithmic slope is for the -mass relation, and
for the -mass relation, consistent with previous estimations on mock
catalogues and coherent with the different nature of the two observables.Comment: 19 pages, 16 figures, accepted by MNRA
CoMaLit -- VI. Intrinsic scatter in stacked relations. The weak lensing AMICO galaxy clusters in KiDS-DR3
Unbiased and precise mass calibration of galaxy clusters is crucial to fully
exploit galaxy clusters as cosmological probes. Stacking of weak lensing signal
allows us to measure observable-mass relations down to less massive halos halos
without extrapolation. We propose a Bayesian inference method to constrain the
intrinsic scatter of the mass proxy in stacked analyses. The scatter of the
stacked data is rescaled with respect to the individual scatter based on the
number of binned clusters. We apply this method to the galaxy clusters detected
with the AMICO (Adaptive Matched Identifier of Clustered Objects) algorithm in
the third data release of the Kilo-Degree Survey. The results confirm the
optical richness as a low scatter mass proxy. Based on the optical richness and
the calibrated weak lensing mass-richness relation, mass of individual objects
down to ~10^13 solar masses can be estimated with a precision of ~20 per cent.Comment: 12 pages, 6 figures; in press on MNRA
Outskirts of Galaxy Clusters
Until recently, only about 10% of the total intracluster gas volume had been
studied with high accuracy, leaving a vast region essentially unexplored. This
is now changing and a wide area of hot gas physics and chemistry awaits
discovery in galaxy cluster outskirts. Also, robust large-scale total mass
profiles and maps are within reach. First observational and theoretical results
in this emerging field have been achieved in recent years with sometimes
surprising findings. Here, we summarize and illustrate the relevant underlying
physical and chemical processes and review the recent progress in X-ray,
Sunyaev--Zel'dovich, and weak gravitational lensing observations of cluster
outskirts, including also brief discussions of technical challenges and
possible future improvements.Comment: 52 pages. Review paper. Accepted for publication in Space Science
Reviews (eds: S. Ettori, M. Meneghetti). This is a product of the work done
by an international team at the International Space Science Institute (ISSI)
in Bern on "Astrophysics and Cosmology with Galaxy Clusters: the X-ray and
Lensing View
Simulating the impact of dust cooling on the statistical properties of the intracluster medium
From the first stages of star and galaxy formation, non-gravitational
processes such as ram pressure stripping, SNs, galactic winds, AGNs,
galaxy-galaxy mergers, etc... lead to the enrichment of the IGM in stars,
metals as well as dust, via the ejection of galactic material into the IGM. We
know now that these processes shape, side by side with gravitation, the
formation and the evolution of structures. We present here hydrodynamic
simulations of structure formation implementing the effect of the cooling by
dust on large scale structure formation. We focus on the scale of galaxy
clusters and study the statistical properties of clusters. Here we present our
results on the and the scaling relations which exhibit changes
on both the slope and normalization when adding cooling by dust to the standard
radiative cooling model. For example, the normalization of the relation
changes only by a maximum of 2% at M whereas the
normalization of the changes by as much as 10% at keV for
models that including dust cooling. Our study shows that the dust is an added
non-gravitational process that contributes shaping the thermodynamical state of
the hot ICM gas.Comment: 11 pages, 4 figures, ASR in pres
AMICO galaxy clusters in KiDS-DR3: galaxy population properties and their redshift dependence
A catalogue of galaxy clusters was obtained in an area of 414 sq deg up to a
redshift from the Data Release 3 of the Kilo-Degree Survey
(KiDS-DR3), using the Adaptive Matched Identifier of Clustered Objects (AMICO)
algorithm. The catalogue and the calibration of the richness-mass relation were
presented in two companion papers. Here we describe the selection of the
cluster central galaxy and the classification of blue and red cluster members,
and analyze the main cluster properties, such as the red/blue fraction, cluster
mass, brightness and stellar mass of the central galaxy, and their dependence
on redshift and cluster richness. We use the Illustris-TNG simulation, which
represents the state-of-the-art cosmological simulation of galaxy formation, as
a benchmark for the interpretation of the results. A good agreement with
simulations is found at low redshifts (), while at higher redshifts
the simulations indicate a lower fraction of blue galaxies than what found in
the KiDS-AMICO catalogue: we argue that this may be due to an underestimate of
star-forming galaxies in the simulations. The selection of clusters with a
larger magnitude difference between the two brightest central galaxies, which
may indicate a more relaxed cluster dynamical status, improves the agreement
between the observed and simulated cluster mass and stellar mass of the central
galaxy. We also find that at a given cluster mass the stellar mass of blue
central galaxies is lower than that of the red ones.Comment: 14 pages, 16 figures, accepted for publication on MNRA