scholarly journals The cosmological analysis of X-ray cluster surveys

2018 ◽  
Vol 614 ◽  
pp. A72 ◽  
Author(s):  
A. Valotti ◽  
M. Pierre ◽  
A. Farahi ◽  
A. Evrard ◽  
L. Faccioli ◽  
...  
Keyword(s):  
Cosmological Parameters ◽  
Scaling Relations ◽  
Temperature Relation ◽  
Local Scaling ◽  
X Ray ◽  
Mass Size ◽  
Final Error ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Size Relation

Context. This paper is the fourth of a series evaluating the ASpiX cosmological method, based on X-ray diagrams, which are constructed from simple cluster observable quantities, namely: count rate (CR), hardness ratio (HR), core radius (rc), and redshift. Aims. Following extensive tests on analytical toy catalogues (Paper III), we present the results of a more realistic study over a 711 deg2 template-based maps derived from a cosmological simulation. Methods. Dark matter haloes from the Aardvark simulation have been ascribed luminosities, temperatures, and core radii, using local scaling relations and assuming self-similar evolution. The predicted X-ray sky-maps were converted into XMM event lists, using a detailed instrumental simulator. The XXL pipeline runs on the resulting sky images, produces an observed cluster catalogue over which the tests have been performed. This allowed us to investigate the relative power of various combinations of the CR, HR, rc, and redshift information. Two fitting methods were used: a traditional Markov chain Monte Carlo (MCMC) approach and a simple minimisation procedure (Amoeba) whose mean uncertainties are a posteriori evaluated by means of synthetic catalogues. The results were analysed and compared to the predictions from the Fisher analysis (FA). Results. For this particular catalogue realisation, assuming that the scaling relations are perfectly known, the CR-HR combination gives σ8 and Ωm at the 10% level, while CR-HR-rc-z improves this to ≤3%. Adding a second HR improves the results from the CR-HR1-rc combination, but to a lesser extent than when adding the redshift information. When all coefficients of the mass-temperature relation (M-T, including scatter) are also fitted, the cosmological parameters are constrained to within 5–10% and larger for the M-T coefficients (up to a factor of two for the scatter). The errors returned by the MCMC, those by Amoeba and the FA predictions are in most cases in excellent agreement and always within a factor of two. We also study the impact of the scatter of the mass-size relation (M-Rc) on the number of detected clusters: for the cluster typical sizes usually assumed, the larger the scatter, the lower the number of detected objects. Conclusions. The present study confirms and extends the trends outlined in our previous analyses, namely the power of X-ray observable diagrams to successfully and easily fit at the same time, the cosmological parameters, cluster physics, and the survey selection, by involving all detected clusters. The accuracy levels quoted should not be considered as definitive. A number of simplifying hypotheses were made for the testing purpose, but this should affect any method in the same way. The next publication will consider in greater detail the impact of cluster shapes (selection and measurements) and of cluster physics on the final error budget by means of hydrodynamical simulations.

scholarly journals Anisotropy of the galaxy cluster X-ray luminosity–temperature relation

2018 ◽  
Vol 611 ◽  
pp. A50 ◽  
Author(s):  
Konstantinos Migkas ◽  
Thomas H. Reiprich
Keyword(s):  
Galaxy Clusters ◽  
Statistical Significance ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
Luminosity Distance ◽  
Temperature Relation ◽  
X Ray ◽  
Two Samples ◽  
The Galaxy ◽  
Group A

We introduce a new test to study the cosmological principle with galaxy clusters. Galaxy clusters exhibit a tight correlation between the luminosity and temperature of the X-ray-emitting intracluster medium. While the luminosity measurement depends on cosmological parameters through the luminosity distance, the temperature determination is cosmology-independent. We exploit this property to test the isotropy of the luminosity distance over the full extragalactic sky, through the normalization a of the LX–T scaling relation and the cosmological parameters Ωm and H0. To this end, we use two almost independent galaxy cluster samples: the ASCA Cluster Catalog (ACC) and the XMM Cluster Survey (XCS-DR1). Interestingly enough, these two samples appear to have the same pattern for a with respect to the Galactic longitude. More specifically, we identify one sky region within l ~ (−15°, 90°) (Group A) that shares very different best-fit values for the normalization of the LX–T relation for both ACC and XCS-DR1 samples. We use the Bootstrap and Jackknife methods to assess the statistical significance of these results. We find the deviation of Group A, compared to the rest of the sky in terms of a, to be ~2.7σ for ACC and ~3.1σ for XCS-DR1. This tension is not significantly relieved after excluding possible outliers and is not attributed to different redshift (z), temperature (T), or distributions of observable uncertainties. Moreover, a redshift conversion to the cosmic microwave background (CMB) frame does not have an important impact on our results. Using also the HIFLUGCS sample, we show that a possible excess of cool-core clusters in this region, is not able to explain the obtained deviations. Furthermore, we tested for a dependence of the results on supercluster environment, where the fraction of disturbed clusters might be enhanced, possibly affecting the LX–T relation. We indeed find a trend in the XCS-DR1 sample for supercluster members to be underluminous compared to field clusters. However, the fraction of supercluster members is similar in the different sky regions, so this cannot explain the observed differences, either. Constraining Ωm and H0 via the redshift evolution of LX–T and the luminosity distance via the flux–luminosity conversion, we obtain approximately the same deviation amplitudes as for a. It is interesting that the general observed behavior of Ωm for the sky regions that coincide with the CMB dipole is similar to what was found with other cosmological probes such as supernovae Ia. The reason for this behavior remains to be identified.

scholarly journals On the impact of baryons on the halo mass function, bias, and cluster cosmology

2020 ◽  
Vol 500 (2) ◽  
pp. 2316-2335
Author(s):  
Tiago Castro ◽  
Stefano Borgani ◽  
Klaus Dolag ◽  
Valerio Marra ◽  
Miguel Quartin ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Cosmological Parameters ◽  
High Sensitivity ◽  
Mass Function ◽  
Quality Data ◽  
Systematic Uncertainties ◽  
Statistical Precision ◽  
Supernova Explosions ◽  
Hydrodynamical Simulations ◽  
The Impact

ABSTRACT Luminous matter produces very energetic events, such as active galactic nuclei and supernova explosions, that significantly affect the internal regions of galaxy clusters. Although the current uncertainty in the effect of baryonic physics on cluster statistics is subdominant as compared to other systematics, the picture is likely to change soon as the amount of high-quality data is growing fast, urging the community to keep theoretical systematic uncertainties below the ever-growing statistical precision. In this paper, we study the effect of baryons on galaxy clusters, and their impact on the cosmological applications of clusters, using the magneticum suite of cosmological hydrodynamical simulations. We show that the impact of baryons on the halo mass function can be recast in terms on a variation of the mass of the haloes simulated with pure N-body, when baryonic effects are included. The halo mass function and halo bias are only indirectly affected. Finally, we demonstrate that neglecting baryonic effects on haloes mass function and bias would significantly alter the inference of cosmological parameters from high-sensitivity next-generations surveys of galaxy clusters.

scholarly journals Probing cosmic isotropy with a new X-ray galaxy cluster sample through the LX–T scaling relation

2020 ◽  
Vol 636 ◽  
pp. A15 ◽  
Author(s):  
K. Migkas ◽  
G. Schellenberger ◽  
T. H. Reiprich ◽  
F. Pacaud ◽  
M. E. Ramos-Ceja ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Statistical Significance ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
Temperature Measurements ◽  
Joint Analysis ◽  
Scaling Relations ◽  
Exact Nature ◽  
X Rays ◽  
X Ray

The isotropy of the late Universe and consequently of the X-ray galaxy cluster scaling relations is an assumption greatly used in astronomy. However, within the last decade, many studies have reported deviations from isotropy when using various cosmological probes; a definitive conclusion has yet to be made. New, effective and independent methods to robustly test the cosmic isotropy are of crucial importance. In this work, we use such a method. Specifically, we investigate the directional behavior of the X-ray luminosity-temperature (LX–T) relation of galaxy clusters. A tight correlation is known to exist between the luminosity and temperature of the X-ray-emitting intracluster medium of galaxy clusters. While the measured luminosity depends on the underlying cosmology through the luminosity distance DL, the temperature can be determined without any cosmological assumptions. By exploiting this property and the homogeneous sky coverage of X-ray galaxy cluster samples, one can effectively test the isotropy of cosmological parameters over the full extragalactic sky, which is perfectly mirrored in the behavior of the normalization A of the LX–T relation. To do so, we used 313 homogeneously selected X-ray galaxy clusters from the Meta-Catalogue of X-ray detected Clusters of galaxies. We thoroughly performed additional cleaning in the measured parameters and obtain core-excised temperature measurements for all of the 313 clusters. The behavior of the LX–T relation heavily depends on the direction of the sky, which is consistent with previous studies. Strong anisotropies are detected at a ≳4σ confidence level toward the Galactic coordinates (l, b) ∼ (280°, − 20°), which is roughly consistent with the results of other probes, such as Supernovae Ia. Several effects that could potentially explain these strong anisotropies were examined. Such effects are, for example, the X-ray absorption treatment, the effect of galaxy groups and low redshift clusters, core metallicities, and apparent correlations with other cluster properties, but none is able to explain the obtained results. Analyzing 105 bootstrap realizations confirms the large statistical significance of the anisotropic behavior of this sky region. Interestingly, the two cluster samples previously used in the literature for this test appear to have a similar behavior throughout the sky, while being fully independent of each other and of our sample. Combining all three samples results in 842 different galaxy clusters with luminosity and temperature measurements. Performing a joint analysis, the final anisotropy is further intensified (∼5σ), toward (l, b) ∼ (303°, − 27°), which is in very good agreement with other cosmological probes. The maximum variation of DL seems to be ∼16 ± 3% for different regions in the sky. This result demonstrates that X-ray studies that assume perfect isotropy in the properties of galaxy clusters and their scaling relations can produce strongly biased results whether the underlying reason is cosmological or related to X-rays. The identification of the exact nature of these anisotropies is therefore crucial for any statistical cluster physics or cosmology study.

scholarly journals Cosmological hydrodynamical simulations of galaxy clusters: X-ray scaling relations and their evolution

2017 ◽  
Vol 474 (3) ◽  
pp. 4089-4111 ◽  
Author(s):  
N Truong ◽  
E Rasia ◽  
P Mazzotta ◽  
S Planelles ◽  
V Biffi ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Scaling Relations ◽  
X Ray ◽  
Hydrodynamical Simulations

scholarly journals Physical properties and scaling relations of molecular clouds: the impact of star formation

2020 ◽  
Vol 500 (3) ◽  
pp. 3552-3568
Author(s):  
Kearn Grisdale
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Milky Way ◽  
Free Fall ◽  
Scaling Relations ◽  
Formation Method ◽  
Hydrodynamical Simulations ◽  
Formation Efficiency ◽  
The Impact ◽  
Very High

ABSTRACT Using hydrodynamical simulations of a Milky Way-like galaxy, reaching 4.6 pc resolution, we study how the choice of star formation criteria impacts both galactic and giant molecular cloud (GMC) scales. We find that using a turbulent, self-gravitating star formation criteria leads to an increase in the fraction of gas with densities between 10 and $10^{4}{\, \rm {cm^{-3}}}$ when compared with a simulation using a molecular star formation method, despite both having nearly identical gaseous and stellar morphologies. Furthermore, we find that the site of star formation is effected with the the former tending to only produce stars in regions of very high density (${\gt}10^{4}{\, \rm {cm^{-3}}}$) gas, while the latter forms stars along the entire length of its spiral arms. The properties of GMCs are impacted by the choice of star formation criteria with the former method producing larger clouds. Despite the differences, we find that the relationships between clouds properties, such as the Larson relations, remain unaffected. Finally, the scatter in the measured star formation efficiency per free-fall time of GMCs remains present with both methods and is thus set by other factors.

scholarly journals AGN feedback and the origin and fate of the hot gas in early-type galaxies

2018 ◽  
Vol 14 (S342) ◽  
pp. 97-100
Author(s):  
Silvia Pellegrini ◽  
Luca Ciotti ◽  
Andrea Negri ◽  
Jeremiah P. Ostriker
Keyword(s):  
Stellar Population ◽  
Gas Content ◽  
Large Set ◽  
Early Type ◽  
X Ray ◽  
Hot Gas ◽  
Hydrodynamical Simulations ◽  
Consistent Treatment ◽  
The Impact ◽  
Recycled Material

AbstractWe present the results of two-dimensional, grid-type hydrodynamical simulations, with parsec-scale central resolution, for the evolution of the hot gas in isolated early-type galaxies (ETGs). The simulations include a physically self-consistent treatment of the mechanical (from winds) and radiative AGN feedback, and were run for a large set of realistic galaxy models. AGN feedback proves to be very important to maintain massive ETGs in a time-averaged quasi-steady state, keeping the star formation at a low level, and the central black hole mass on observed scaling relations. A comparison with recent determinations of the X-ray properties of ETGs in the local universe shows that, at later epochs, AGN feedback does not dramatically alter the gas content originating in stellar recycled material. Thus, the present-day X-ray luminosity is not a robust diagnostic of the impact of AGN activity, within a scenario where the hot gas mostly originates from the stellar population.

scholarly journals Growth and instability of the liquid rim in the crown splash regime

2014 ◽  
Vol 752 ◽  
pp. 485-496 ◽  
Author(s):  
G. Agbaglah ◽  
R. D. Deegan
Keyword(s):  
Thin Film ◽  
High Speed ◽  
Unstable Mode ◽  
Linear Stability Theory ◽  
Scaling Relations ◽  
X Ray ◽  
X Ray Imaging ◽  
Secondary Droplets ◽  
The Impact ◽  
Good Agreement

AbstractWe study the formation, growth and disintegration of jets following the impact of a drop on a thin film of the same liquid for $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{We}<1000$ and $\mathit{Re}<2000$ using a combination of numerical simulations and linear stability theory (Agbaglah, Josserand & Zaleski, Phys. Fluids, vol. 25, 2013, 022103). Our simulations faithfully capture this phenomena and are in good agreement with experimental profiles obtained from high-speed X-ray imaging. We obtain scaling relations from our simulations and use these as inputs to our stability analysis. The resulting predictions for the most unstable wavelength are in excellent agreement with experimental data. Our calculations show that the dominant destabilizing mechanism is a competition between capillarity and inertia but that deceleration of the rim provides an additional boost to growth. We also predict over the entire parameter range of our study the number and timescale for formation of secondary droplets formed during a splash, based on the assumption that the most unstable mode sets the droplet number.

scholarly journals The impact of mergers on relaxed X-ray clusters – II. Effects on global X-ray and Sunyaev–Zel'dovich properties and their scaling relations

2007 ◽  
Vol 380 (2) ◽  
pp. 437-454 ◽  
Author(s):  
Gregory B. Poole ◽  
Arif Babul ◽  
Ian G. McCarthy ◽  
Mark A. Fardal ◽  
C. J. Bildfell ◽  
...  
Keyword(s):  
Scaling Relations ◽  
X Ray ◽  
The Impact

scholarly journals A general framework to test gravity using galaxy clusters III: Observable-mass scaling relations in f(R) gravity

2021 ◽  
Author(s):  
Myles A Mitchell ◽  
Christian Arnold ◽  
Baojiu Li
Keyword(s):  
Galaxy Formation ◽  
General Framework ◽  
Accurate Determination ◽  
Galaxy Cluster ◽  
Scaling Relations ◽  
Gas Temperature ◽  
Temperature Relation ◽  
X Ray ◽  
Mass Scaling ◽  
Cluster Mass

Abstract We test two methods, including one that is newly proposed in this work, for correcting for the effects of chameleon f(R) gravity on the scaling relations between the galaxy cluster mass and four observable proxies. Using the first suite of cosmological simulations that simultaneously incorporate both full physics of galaxy formation and Hu-Sawicki f(R) gravity, we find that these rescaling methods work with a very high accuracy for the gas temperature, the Compton Y-parameter of the Sunyaev-Zel’dovich (SZ) effect and the X-ray analogue of the Y-parameter. This allows the scaling relations in f(R) gravity to be mapped to their ΛCDM counterparts to within a few percent. We confirm that a simple analytical tanh formula for the ratio between the dynamical and true masses of haloes in chameleon f(R) gravity, proposed and calibrated using dark-matter-only simulations in a previous work, works equally well for haloes identified in simulations with two very different – full-physics and non-radiative – baryonic models. The mappings of scaling relations can be computed using this tanh formula, which depends on the halo mass, redshift and size of the background scalar field, also at a very good accuracy. Our results can be used for accurate determination of the cluster mass using SZ and X-ray observables, and will form part of a general framework for unbiased and self-consistent tests of gravity using data from present and upcoming galaxy cluster surveys. We also propose an alternative test of gravity, using the YX-temperature relation, which does not involve mass calibration.

scholarly journals Impact of systematics on cosmological parameters from future galaxy cluster surveys

2020 ◽  
Vol 643 ◽  
pp. A20 ◽  
Author(s):  
Laura Salvati ◽  
Marian Douspis ◽  
Nabila Aghanim
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Galaxy Clusters ◽  
Cosmological Parameters ◽  
Mass Function ◽  
Function Evaluation ◽  
Scaling Relations ◽  
The Impact ◽  
Parameter Constraints ◽  
Mass Functions

Galaxy clusters are a recent cosmological probe. The precision and accuracy of the cosmological parameters inferred from these objects are affected by the knowledge of cluster physics, entering the analysis through the mass-observable scaling relations, and the theoretical description of their mass and redshift distribution, modelled by the mass function. In this work we forecast the impact of different modelling of these ingredients for clusters detected by future optical and near-IR surveys. We consider the standard cosmological scenario and the case with a time-dependent equation of state for dark energy. We analyse the effect of increasing precision on the scaling relation calibration, finding improved constraints on the cosmological parameters. This higher precision exposes the impact of the mass function evaluation, which is a subdominant source of systematics for current data. We compare two different evaluations for the mass function. In both cosmological scenarios the use of different mass functions leads to biases in the parameter constraints. For the ΛCDM model, we find a 1.6σ shift in the (Ωm, σ8) parameter plane and a discrepancy of ∼7σ for the redshift evolution of the scatter of the scaling relations. For the scenario with a time-evolving dark energy equation of state, the assumption of different mass functions results in a ∼8σ tension in the w0 parameter. These results show the impact, and the necessity for a precise modelling, of the interplay between the redshift evolution of the mass function and of the scaling relations in the cosmological analysis of galaxy clusters.

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