ABSTRACT
Cosmic voids occupy most of the volume of the Universe, and their statistical properties can be exploited for constraining dark energy, as well as for testing theories of gravity. ...Nevertheless, in spite of their growing popularity as cosmological probes, a gap of knowledge between cosmic void observations and theory still persists. In particular, the void size function models proposed in literature have been proven unsuccessful in reproducing the results obtained from cosmological simulations in which cosmic voids are detected from biased tracers of the density field. The goal of this work is to cover this gap. In particular, we make use of the findings of a previous work in which we have improved the void selection procedure, presenting an algorithm that redefines the void ridges and, consequently, their radii. By applying this algorithm, we validate the volume conserving model of the void size function on a set of unbiased simulated density field tracers. We highlight the difference in the internal structure between voids selected in this way and those identified by the popular vide void finder. We also extend the validation of the model to the case of biased tracers. We find that a relation exists between the tracer used to sample the underlying dark matter density field and its unbiased counterpart. Moreover, we demonstrate that, as long as this relation is accounted for, the size function is a viable approach for studying cosmology with cosmic voids.
Aims.
We present a cosmological analysis of abundances and stacked weak lensing profiles of galaxy clusters, exploiting the AMICO KiDS-DR3 catalogue. The sample consists of 3652 galaxy clusters with ...intrinsic richness
λ
*
≥ 20, over an effective area of 377 deg
2
, in the redshift range
z
∈ 0.1, 0.6.
Methods.
We quantified the purity and completeness of the sample through simulations. The statistical analysis has been performed by simultaneously modelling the co-moving number density of galaxy clusters and the scaling relation between the intrinsic richnesses and the cluster masses, assessed through stacked weak lensing profile modelling. The fluctuations of the matter background density, caused by super-survey modes, have been taken into account in the likelihood. Assuming a flat Λ cold dark matter (ΛCDM) model, we constrained Ω
m
,
σ
8
,
S
8
≡
σ
8
(Ω
m
/0.3)
0.5
, and the parameters of the mass-richness scaling relation.
Results.
We obtained Ω
m
= 0.24
−0.04
+0.03
,
σ
8
= 0.86
−0.07
+0.07
, and
S
8
= 0.78
−0.04
+0.04
. The constraint on
S
8
is consistent within 1
σ
with the results from WMAP and Planck. Furthermore, we got constraints on the cluster mass scaling relation in agreement with those obtained from a previous weak lensing only analysis.
We provide fits to the distribution of galaxy luminosity, size, velocity dispersion and stellar mass as a function of concentration index Cr and morphological type in the Sloan Digital Sky Survey ...(SDSS). (Our size estimate, a simple analogue of the SDSS cmodel magnitude, is new: it is computed using a combination of seeing-corrected quantities in the SDSS data base, and is in substantially better agreement with results from more detailed bulge/disc decompositions.) We also quantify how estimates of the fraction of ‘early’- or ‘late’-type galaxies depend on whether the samples were cut in colour, concentration or light profile shape, and compare with similar estimates based on morphology. Our fits show that ellipticals account for about 20 per cent of the r-band luminosity density, , and 25 per cent of the stellar mass density, ρ*; including S0s and Sas increases these numbers to 33 per cent and 40 per cent, and 50 per cent and 60 per cent, respectively. The values of and ρ*, and the mean sizes, of E, E+S0 and E+S0+Sa samples are within 10 per cent of those in the Hyde & Bernardi, Cr≥ 2.86 and Cr≥ 2.6 samples, respectively. Summed over all galaxy types, we find ρ*∼ 3 × 108 M⊙ Mpc−3 at z∼ 0. This is in good agreement with expectations based on integrating the star formation history. However, compared to most previous work, we find an excess of objects at large masses, up to a factor of ∼10 at M*∼ 5 × 1011 M⊙. The stellar mass density further increases at large masses if we assume different initial mass functions for elliptical and spiral galaxies, as suggested by some recent chemical evolution models, and results in a better agreement with the dynamical mass function. We also show that the trend for ellipticity to decrease with luminosity is primarily because the E/S0 ratio increases at large L. However, the most massive galaxies, M*≥ 5 × 1011 M⊙, are less concentrated and not as round as expected if one extrapolates from lower L, and they are not well fit by pure deVaucouleur laws. This suggests formation histories with recent radial mergers. Finally, we show that the age–size relation is flat for ellipticals of fixed dynamical mass, but, at fixed Mdyn, S0s and Sas with large sizes tend to be younger. Hence, samples selected on the basis of colour or Cr will yield different scalings. Explaining this difference between E and S0 formation is a new challenge for models of early-type galaxy formation.
We investigate the main tensions within the current standard model of cosmology from the perspective of the main statistics of cosmic voids, using the final BOSS DR12 data set. For this purpose, we ...present the first estimate of the
S
8
≡
σ
8
Ω
m
/0.3 and
H
0
parameters obtained from void number counts and shape distortions. To analyze void counts we relied on an extension of the popular volume-conserving model for the void size function, tailored to the application on data, including geometric and dynamic distortions. We calibrated the two nuisance parameters of this model with the official BOSS Collaboration mock catalogs and propagated their uncertainty through the statistical analysis of the BOSS void number counts. The constraints from void shapes come from the study of the geometric distortions of the stacked void-galaxy cross-correlation function. In this work we focus our analysis on the Ω
m
−
σ
8
and Ω
m
−
H
0
parameter planes and derive the marginalized constraints
S
8
= 0.813
−0.068
+0.093
and
H
0
= 67.3
−9.1
+10.0
km s
−1
Mpc
−1
, which are fully compatible with constraints from the literature. These results are expected to notably improve in precision when analyzed jointly with independent probes and will open a new viewing angle on the rising cosmological tensions in the near future.
We analyse the largest spectroscopic samples of galaxy clusters to date, and provide observational constraints on the distance–redshift relation from baryon acoustic oscillations. The cluster samples ...considered in this work have been extracted from the Sloan Digital Sky Survey at three median redshifts, z = 0.2, 0.3 and 0.5. The number of objects is 12 910, 42 215 and 11 816, respectively. We detect the peak of baryon acoustic oscillations for all the three samples. The derived distance constraints are r
s/D
V
(z = 0.2) = 0.18 ± 0.01, r
s/D
V
(z = 0.3) = 0.124 ± 0.004 and r
s/D
V
(z = 0.5) = 0.080 ± 0.002. Combining these measurements with the sound horizon scale measured from the cosmic microwave background, we obtain robust constraints on cosmological parameters. Our results are in agreement with the standard Λ cold dark matter (ΛCDM) model. Specifically, we constrain the Hubble constant in a ΛCDM model,
$H_0 = 64_{-8}^{+17} \, \, \mathrm{km} \, \mathrm{s}^{-1}\,\mathrm{Mpc}^{-1} \,$
, the density of curvature energy, in the oΛCDM context,
$\Omega _K = -0.01_{-0.33}^{+0.34}$
, and finally the parameter of the dark energy equation of state in the wCDM case,
$w = -1.06_{-0.52}^{+0.49}$
. This is the first time the distance–redshift relation has been constrained using only the peak of baryon acoustic oscillations of galaxy clusters.
ABSTRACT
Galaxy clusters and cosmic voids, the most extreme objects in our Universe in terms of mass and size, trace two opposite sides of the large-scale matter density field. By studying their ...abundance as a function of their mass and radius, respectively, i.e. the halo mass function (HMF) and void size function (VSF), it is possible to achieve fundamental constraints on the cosmological model. While the HMF has already been extensively exploited, providing robust constraints on the main cosmological model parameters (e.g. Ωm, σ8, and S8), the VSF is still emerging as a viable and effective cosmological probe. Given the expected complementarity of these statistics, in this work, we aim at estimating the costraining power deriving from their combination. To this end, we exploit realistic mock samples of galaxy clusters and voids extracted from state-of-the-art large hydrodynamical simulations, in the redshift range 0.2 ≤ z ≤ 1. We perform an accurate calibration of the free parameters of the HMF and VSF models, needed to take into account the differences between the types of mass tracers used in this work and those considered in previous literature analyses. Then, we obtain constraints on Ωm and σ8 by performing a Bayesian analysis. We find that cluster and void counts represent powerful independent and complementary probes to test the cosmological framework. In particular, the constraining power of the HMF on Ωm and σ8 improves with the VSF contribution, increasing the S8 constraint precision by a factor of about 60 per cent.
We detect the peak of baryon acoustic oscillations (BAO) in the two-point correlation function of a spectroscopic sample of 25 226 clusters selected from the Sloan Digital Sky Survey. Galaxy ...clusters, as tracers of massive dark matter haloes, are highly biased structures. The linear bias b of the sample considered in this work, that we estimate from the projected correlation function, is b σ8 = 1.72 ± 0.03. Thanks to the high signal in the cluster correlation function and to the accurate spectroscopic redshift measurements, we can clearly detect the BAO peak and determine its position, s
p, with high accuracy, despite the relative paucity of the sample. Our measurement, s
p = 104 ± 7 Mpc h
−1, is in good agreement with previous estimates from large galaxy surveys, and has a similar uncertainty. The BAO measurement presented in this work thus provides a new strong confirmation of the concordance cosmological model and demonstrates the power and promise of galaxy clusters as key probes for cosmological applications based on large-scale structures.
We present the first quantitative detection of large-scale filamentary structure at z NOT approximately equal to 0.7 in the large cosmological volume probed by the VIMOS Public Extragalactic ...Redshift Survey (VIPERS). We use simulations to show the capability of VIPERS to recover robust topological features in the galaxy distribution, in particular the filamentary network. We then investigate how galaxies with different stellar masses and stellar activities are distributed around the filaments, and find a significant segregation, with the most massive or quiescent galaxies being closer to the filament axis than less massive or active galaxies. The signal persists even after downweighting the contribution of peak regions. Our results suggest that massive and quiescent galaxies assemble their stellar mass through successive mergers during their migration along filaments towards the nodes of the cosmic web. On the other hand, low-mass star-forming galaxies prefer the outer edge of filaments, a vorticity-rich region dominated by smooth accretion, as predicted by the recent spin alignment theory. This emphasizes the role of large-scale cosmic flows in shaping galaxy properties.
Aims.
By means of the
r
-band luminosity function (LF) of galaxies in a sample of about 4000 clusters detected by the cluster finder AMICO in the KiDS-DR3 area of about 400 deg
2
, we studied the ...evolution with richness and redshift of the passive evolving (red), star-forming (blue), and total galaxy populations. This analysis was performed for clusters in the redshift range 0.1, 0.8 and in the mass range 10
13
M
⊙
, 10
15
M
⊙
.
Methods.
To compute LFs, we binned the luminosity distribution in magnitude and statistically subtracted the background. Then, we divided the cluster sample in bins of both redshift and richness/mass. We stacked LF counts in each 2D bin for the total, red, and blue galaxy populations; finally, we fitted the stacked LF with a Schechter function and studied the trend of its parameters with redshift and richness/mass.
Results.
We found a passive evolution with
z
for the bright part of the LF for the red and total populations and no significant trends for the faint galaxies. The mass/richness dependence is clear for the density parameter Φ
⋆
, increasing with richness, and for the total population faint end, which is shallower in the rich clusters.
ABSTRACT
We constrain the ΛCDM cosmological parameter σ8 by applying the extreme value statistics for galaxy cluster mass on the AMICO KiDS-DR3 catalogue. We sample the posterior distribution of the ...parameters by considering the likelihood of observing the largest cluster mass value in a sample of Nobs = 3644 clusters with intrinsic richness λ* > 20 in the redshift range z ∈ 0.10, 0.60. We obtain $\sigma _{8}=0.90_{-0.18}^{+0.20}$, consistent within 1σ with the measurements obtained by the Planck collaboration and with previous results from cluster cosmology exploiting AMICO KiDS-DR3. The constraints could improve by applying this method to forthcoming missions, such as Euclid and LSST, which are expected to deliver thousands of distant and massive clusters.
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