Abstract
The role of the cosmic web in shaping galaxy properties is investigated in the Galaxy And Mass Assembly (GAMA) spectroscopic survey in the redshift range 0.03 ≤ z ≤ 0.25. The stellar mass, ...u − r dust corrected colour and specific star formation rate (sSFR) of galaxies are analysed as a function of their distances to the 3D cosmic web features, such as nodes, filaments and walls, as reconstructed by DisPerSE. Significant mass and type/colour gradients are found for the whole population, with more massive and/or passive galaxies being located closer to the filament and wall than their less massive and/or star-forming counterparts. Mass segregation persists among the star-forming population alone. The red fraction of galaxies increases when closing in on nodes, and on filaments regardless of the distance to nodes. Similarly, the star-forming population reddens (or lowers its sSFR) at fixed mass when closing in on filament, implying that some quenching takes place. These trends are also found in the state-of-the-art hydrodynamical simulation Horizon-AGN. These results suggest that on top of stellar mass and large-scale density, the traceless component of the tides from the anisotropic large-scale environment also shapes galactic properties. An extension of excursion theory accounting for filamentary tides provides a qualitative explanation in terms of anisotropic assembly bias: at a given mass, the accretion rate varies with the orientation and distance to filaments. It also explains the absence of type/colour gradients in the data on smaller, non-linear scales.
ABSTRACT
Galaxy clusters exhibit a rich morphology during the early and intermediate stages of mass assembly, especially beyond their boundary. A classification scheme based on shapefinders deduced ...from the Minkowski functionals is examined to fully account for the morphological diversity of galaxy clusters, including relaxed and merging clusters, clusters fed by filamentary structures, and cluster-pair bridges. These configurations are conveniently treated with idealized geometric models and analytical formulas, some of which are novel. Examples from CLASH and LC2 clusters and observed cluster-pair bridges are discussed.
ABSTRACT
A new fully non-linear reconstruction algorithm for the accurate recovery of the baryonic acoustic oscillations (BAO) scale in two-point correlation functions is proposed, based on the least ...action principle and extending the Fast Action Minimisation method by Nusser & Branchini (2000). Especially designed for massive spectroscopic surveys, it is tested on dark matter halo catalogues extracted from the deus-fur Lambda cold dark matter simulation (Reverdy et al. 2015) to trace the trajectories of up to ${\sim }207\, 000$ haloes backward in time, well beyond the first-order Lagrangian approximation. The new algorithm successfully recovers the BAO feature in real and redshift space in both the monopole and the anisotropic two-point correlation function, also for anomalous samples showing misplaced or absent signature of BAO. In redshift space, the non-linear displacement parameter ΣNL is reduced from $11.8\pm 0.3\, h^{-1}$ Mpc at redshift $z$ = 0 to $4.0\pm 0.5\, h^{-1}$ Mpc at $z$ ≃ 37 after reconstruction. A comparison with the first-order Lagrangian reconstruction is presented, showing that these techniques outperform the linear approximation in recovering an unbiased measurement of the acoustic scale.
ABSTRACT
The morphology of haloes inform about both cosmological and galaxy formation models. We use the Minkowski Functionals (MFs) to characterize the actual morphology of haloes, only partially ...captured by smooth density profile, going beyond the spherical or ellipsoidal symmetry. We employ semi-analytical haloes with NFW and αβγ-profile and spherical or ellipsoidal shape to obtain a clear interpretation of MFs as function of inner and outer slope, concentration and sphericity parameters. We use the same models to mimic the density profile of N-body haloes, showing that their MFs clearly differ as sensitive to internal substructures. This highlights the benefit of MFs at the halo scales as promising statistics to improve the spatial modelling of dark matter, crucial for future lensing, Sunyaev–Zel’dovich, and X-ray mass maps as well as dark matter detection based on high-accuracy data.
ABSTRACT
We present a novel application of the extended Fast Action Minimization method (eFAM) aimed at assessing the role of the environment in shaping galaxy evolution and validate our approach ...against the Magneticum hydrodynamical simulation. We consider the z ≃ 0 snapshot as our observed catalogue and use the reconstructed trajectories of galaxies to model the evolution of cosmic structures. At the statistical level, the fraction of volume occupied by voids, sheets, filaments, and clusters in the reconstructed and simulated high-redshift snapshots agree within 1σ. Locally, we estimate the accuracy of eFAM structures by computing their purity with respect to simulated structures, P, at the cells of a regular grid. Up to z = 1.2, clusters have 0.58 < P < 0.93, filaments vary in 0.90 < P < 0.99, sheets show 0.78 < P < 0.92, and voids have 0.90 < P < 0.92. As redshift increases, comparing reconstructed and simulated tracers becomes more difficult and the purity decreases to P ∼ 0.6. We retrieve the environmental history of individual galaxies by tracing their trajectories through the cosmic web and relate their observed gas fraction, fgas, with the time spent within different structures. For galaxies in clusters and filaments, eFAM reproduces the dependence of fgas on the redshift of accretion/infall as traced by the simulations with a 1.5σ statistical agreement (which decreases to 2.5σ for low-mass galaxies in filaments). These results support the application of eFAM to observational data to study the environmental dependence of galaxy properties, offering a complementary approach to that based on light-cone observations.
ABSTRACT
We present the first application of the extended Fast Action Minimization method (eFAM) to a real data set, the SDSS-DR12 Combined Sample, to reconstruct galaxies orbits back-in-time, their ...two-point correlation function (2PCF) in real-space, and enhance the baryon acoustic oscillation (BAO) peak. For this purpose, we introduce a new implementation of eFAM that accounts for selection effects, survey footprint, and galaxy bias. We use the reconstructed BAO peak to measure the angular diameter distance, $D_\mathrm{A}(z)r^\mathrm{fid}_\mathrm{s}/r_\mathrm{s}$, and the Hubble parameter, $H(z)r_\mathrm{s}/r^\mathrm{fid}_\mathrm{s}$, normalized to the sound horizon scale for a fiducial cosmology $r^\mathrm{fid}_\mathrm{s}$, at the mean redshift of the sample z = 0.38, obtaining $D_\mathrm{A}(z=0.38)r^\mathrm{fid}_\mathrm{s}/r_\mathrm{s}=1090\pm 29$(Mpc)−1, and $H(z=0.38)r_\mathrm{s}/r^\mathrm{fid}_\mathrm{s}=83\pm 3$(km s−1 Mpc−1), in agreement with previous measurements on the same data set. The validation tests, performed using 400 publicly available SDSS-DR12 mock catalogues, reveal that eFAM performs well in reconstructing the 2PCF down to separations of ∼25h−1Mpc, i.e. well into the non-linear regime. Besides, eFAM successfully removes the anisotropies due to redshift-space distortion (RSD) at all redshifts including that of the survey, allowing us to decrease the number of free parameters in the model and fit the full-shape of the back-in-time reconstructed 2PCF well beyond the BAO peak. Recovering the real-space 2PCF, eFAM improves the precision on the estimates of the fitting parameters. When compared with the no-reconstruction case, eFAM reduces the uncertainty of the Alcock-Paczynski distortion parameters α⊥ and α∥ of about 40 per cent and that on the non-linear damping scale Σ∥ of about 70 per cent. These results show that eFAM can be successfully applied to existing redshift galaxy catalogues and should be considered as a reconstruction tool for next-generation surveys alternative to popular methods based on the Zel’dovich approximation.
Context. Oscillation experiments yield strong evidence that at least some neutrinos are massive. As a hot dark-matter component, massive neutrinos should modify the expansion history of the Universe ...as well as the evolution of cosmological perturbations, in a different way from cold dark matter or dark energy. Aims. We use the latest release of CFHTLS cosmic-shear data to constrain the sum of the masses $\sum m_\nu$ of neutrinos, assuming three degenerate mass states. We also consider a joint analysis including other cosmological observables, notably CMB anisotropies, baryonic acoustic oscillations, and distance modulus from type Ia supernovae. Methods. Combining CAMB with a lensing code, we compute the aperture mass variance using a suitable recipe to deal with matter perturbations in the non-linear regime. The statistical analysis is performed by sampling an 8-dimensional likelihood on a regular grid as well as using the importance sampling technique. Results. We obtain the first constraint on neutrino masses based on cosmic-shear data, and combine CFHTLS with WMAP, SDSS, 2dFGRS, Gold-set, and SNLS data. The joint analysis yields 0.03 eV $ < \sum m_\nu < 0.54$ eV at the 95% confidence level. The preference for massive neutrinos vanishes when systematics are included.
Aims. Dark energy can be investigated in two complementary ways, by considering either general parameterizations or physically well-defined models. Following the second route, we explore the ...observational constraints on quintessence models where the acceleration of our universe is driven by a slow-rolling scalar field. Using weak lensing data to investigate high-energy motivated models of dark energy for the first time, the analysis focuses on cosmic shear, examining how weak lensing surveys can constrain dark energy, discussing the limitations due to the lack of knowledge of the non-linear regime, and combining with type Ia supernovae data and cosmic microwave background observations to lift some degeneracies. Methods. Using a Boltzmann code that includes quintessence models along with a weak lensing add-on code, we determine the shear power spectrum and several two-point statistics, describing the non-linear regime by two different mappings. The likelihood analysis completing the pipeline, based on a grid method, uses the "gold set" of supernovae Ia, VIRMOS-Descart and CFHTLS-deep and-wide data for weak lensing; we also explore larger angular scales, using a synthetic realization of the complete CFHTLS-wide survey, as well as of space-based mission surveys. WMAP-first year data are used for the normalization and to broadly define the location of the first acoustic peak constraining the quintessence parameter space. Results. Two classes of cosmological parameters are discussed: i) those accounting for quintessence affect mainly geometrical factors; ii) cosmological parameters specifying the primordial universe strongly depend on the description of the non-linear regime. This dependence is confirmed using wide surveys, by discarding the smaller angular scales to reduce the dependence on the non-linear regime. For a flat universe and a quintessence inverse-power-law potential with slope \alpha, the joint analysis gives \alpha<1 and \Omega_{\mathrm=0.75 at a 95% confidence level, whereas \alpha=2 , \Omega_{\mathrm= 0.74 when including supergravity corrections.
We develop a Principal Component Analysis aimed at classifying a subset of 27 350 spectra of galaxies in the range 0.4 < z < 1.0 collected by the VIMOS Public Extragalactic Redshift Survey (VIPERS). ...We apply an iterative algorithm to simultaneously repair parts of spectra affected by noise and/or sky residuals, and reconstruct gaps due to rest-frame transformation, and obtain a set of orthogonal spectral templates that span the diversity of galaxy types. By taking the three most significant components, we find that we can describe the whole sample without contamination from noise. We produce a catalogue of eigencoefficients and template spectra that will be part of future VIPERS data releases. Our templates effectively condense the spectral information into two coefficients that can be related to the age and star formation rate of the galaxies. We examine the spectrophotometric types in this space and identify early, intermediate, late and starburst galaxies.
The XXL Survey: First Results and Future Pierre, M.; Adami, C.; Birkinshaw, M. ...
Astronomische Nachrichten,
March 2017, Letnik:
338, Številka:
3-Feb
Journal Article, Web Resource
Recenzirano
Odprti dostop
The XXL survey currently covers two 25 deg2 patches with XMM observations of approximately 10 ks. We summarize the scientific results associated with the first release of the XXL dataset, which ...occurred in mid-2016.We review several arguments for increasing the survey depth to 40 ks during the next decade of XMM operations. X-ray(zeta less than 2) cluster, (zeta less than 4) active galactic nuclei (AGN), and cosmic background survey science will then benefit from an extraordinary data reservoir. This, combined with deep multi-lambda observations, will lead to solid standalone cosmological constraints and provide a wealth of information on the formation and evolution of AGN, clusters, and the X-ray background. In particular, it will offer a unique opportunity to pinpoint the zeta greater than1 cluster density. It will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions.
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