The <i>XMM</i> Cluster Survey analysis of the <i>SDSS</i> DR8 redMaPPer catalogue: implications for scatter, selection bias, and isotropy in cluster scaling relations

Giles, Paul; Romer, A. K.; Wilkinson, R. D.; Bermeo, A.; Turner, David J.; Hilton, Matthew; Upsdell, E W; Rooney, Philip; Bhargava, S.; Ebrahimpour, L; Farahi, Arya; Mann, R. G.; Manolopoulou, Maria; Mayers, Julian A.; Vergara, C; Viana, P. T. P.; Collins, Chris; Hollowood, D. L.; Jeltema, T.; Miller, C. J.; Nichol, R. C.; Noorali, R; Splettstoesser, M.; Stott, John P.

doi:10.1093/mnras/stac2414

Cited by 10 publications

(2 citation statements)

References 53 publications

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“…35 See for example discussion in [147][148][149][150]. Let us stress that variations in the cosmological parameters on the sky [90,91] (supported by [110,161,167]), excesses in the cosmic dipole [111-113, 124-131, 168], anomalous bulk flows [154][155][156][157][158] and anisotropies in scaling relations [110,159,165] constitute current results. Clearly, excess or residual dipoles are unexpected within FLRW, at least beyond perturbative level.…”

Section: Prologuementioning

confidence: 64%

“…This observation is supported by a residual dipole in the 'Low z' subsample of the Pantheon SNe data set [160], which is enhanced by higher redshift SNe [161], but the statistical significance is low < 2 σ (see also [119,[162][163][164] for earlier observations of similar features). Moreover, a recent study [165] replicates the original observation with the same data [159], but fails to detect anisotropies in galaxy cluster scaling relations in the SDSS DR8 sample [166], while cautioning that the incomplete declination coverage of the SDSS DR8 sample may mask any anisotropies. 32 This frequency dependence is driven by a larger dipole in the TGSS survey [135], but the same survey exhibits also an anomalous angular power spectrum [136].…”

Section: Prologuementioning

confidence: 80%

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Is the observable Universe consistent with the cosmological principle?

Aluri

Cea

Chingangbam

et al. 2023

Class. Quantum Grav.

106

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The Cosmological Principle (CP) -- the notion that the Universe is spatially isotropic and homogeneous on large scales -- underlies a century of progress in cosmology. It is conventionally formulated through the Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) cosmologies as the spacetime metric, and culminates in the successful and highly predictive $\Lambda$-Cold-Dark-Matter ($\Lambda$CDM) model. Yet, tensions have emerged within the $\Lambda$CDM model, most notably a statistically significant discrepancy in the value of the Hubble constant, $H_0$. Since the notion of cosmic expansion determined by a single parameter is intimately tied to the CP, implications of the $H_0$ tension may extend beyond $\Lambda$CDM to the CP itself. This review surveys current observational hints for deviations from the expectations of the CP, highlighting synergies and disagreements that warrant further study. Setting aside the debate about individual large structures, potential deviations from the CP include variations of cosmological parameters on the sky, discrepancies in the cosmic dipoles, and mysterious alignments in quasar polarizations and galaxy spins. While it is possible that a host of observational systematics are impacting results, it is equally plausible that precision cosmology may have outgrown the FLRW paradigm, an extremely pragmatic but non-fundamental symmetry assumption.

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Section: Prologuementioning

confidence: 64%

Section: Prologuementioning

confidence: 80%

Is the observable Universe consistent with the cosmological principle?

Aluri

Cea

Chingangbam

et al. 2023

Class. Quantum Grav.

106

View full text Add to dashboard Cite

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CODEX: Role of velocity substructure in the scaling relations of galaxy clusters

Damsted,

Finoguenov,

Clerc

et al. 2023

A&A

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Context. The use of galaxy clusters as cosmological probes relies on a detailed understanding of their properties. They define cluster selection and ranking linked to a cosmologically significant cluster mass function. Previous studies have employed small samples of clusters, concentrating on achieving the first calibrations of cluster properties with mass, while the diversity of cluster properties has been revealed via detailed studies. Aims. The large spectroscopic follow-up on the CODEX cluster sample with SDSS and NOT enables a detailed study of hundreds of clusters, lifting the limitations of previous samples. We aim to update the spectroscopic cluster identification of CODEX by running the spectroscopic group finder on the follow-up spectroscopy results and connecting the dynamical state of clusters to their scaling relations. Methods. We implemented a reproducible spectroscopic membership determination and cleaning procedures, based on the redMaPPer membership, running the spectroscopic group finder on the follow-up spectroscopy results and cleaning the membership for spectroscopic outliers. We applied the Anderson-Darling test for velocity substructure and analysed its influence on the scaling relations. We also tested the effect of the X-ray-to-optical centre offset on the scaling relations. Results. We report on the scaling relations between richness, X-ray luminosity, and velocity dispersion for a complete sample of clusters with at least 15 members. Clusters with velocity substructure exhibit enhanced velocity dispersion for a given richness and are characterized by 2.5 times larger scatter. Clusters that have a strong offset in X-ray-to-optical centres have comparable scaling relations as clusters with substructure. We demonstrate that there is a consistency in the parameters of the scaling relations for the low- and high-richness galaxy clusters. Splitting the clusters by redshift, we note a decrease in scatter with redshift in all scaling relations. We localize the redshift range where a high scatter is observed to z < 0.15, which is in agreement with the literature results on the scatter. We note that the increase in scatter for both high- and low-luminosity clusters is z < 0.15, suggesting that both cooling and the resulting active galactic nucleus feedback are at the root of this scatter.

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AGNs in massive galaxy clusters: Role of galaxy merging, infalling groups, cluster mass, and dynamical state

Koulouridis,

Gkini,

Drigga

2024

A&A

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There is compelling evidence that active galactic nuclei (AGNs) in high-density regions have undergone a different evolution than their counterparts in the field, indicating that they are strongly affected by their environment. However, we still lack a comprehensive understanding of the dominant mechanisms that trigger the nucleus and the processes that drive the evolution of AGNs in clusters. To investigate (and possibly disentangle) the various factors that may affect the prevalence of AGNs in cluster galaxies, we selected a sample of 19 thoroughly studied X-ray-selected galaxy clusters from the LoCuSS survey. All these clusters are considered massive, with $M_ M_ and span a narrow redshift range between $z and 0.28. We divided the cluster surroundings into two concentric annuli with a width of $R_ $ radius. We considered the first annulus as the central cluster region and the second as the outskirts. We further divided the cluster sample based on the presence of infalling X-ray-detected groups, cluster mass, or dynamical state. We determined the AGN fraction in cluster galaxies of the various sub-samples by correlating the X-ray point-like sources selected from the 4XMM DR10 catalogue with the highly complete spectroscopic catalogue of cluster members obtained with Hectospec. We subsequently used the optical spectra to determine the type of nuclear activity and we visually inspected the host morphology for indications of galaxy mergers or other interactions. We found that the X-ray AGN fraction in the outskirts is consistent with the field, but it is significantly lower in cluster centres, in agreement with previous results for massive clusters. We show that these results do not depend on cluster mass, at least within our cluster mass range, nor on the presence of X-ray-detected infalling groups. Furthermore, we did not find any evidence of a spatial correlation between infalling groups and AGNs. Nevertheless, a significant excess of X-ray AGNs is found in the outskirts of relaxed clusters at the 2sigma confidence level, compared both to non-relaxed clusters and to the field. Finally, according to the literature, the fraction of broad- to narrow-line AGNs in clusters is roughly consistent with the field. However, broad-line AGNs may be preferably located in cluster centres. In the outskirts, the optical spectra of X-ray AGNs present narrow emission lines or they are dominated by stellar emission. Our results suggest that the mechanisms that trigger AGN activity may vary between cluster centres and the outskirts. Ram pressure can efficiently remove the gas from infalling galaxies, thereby triggering AGN activity in some cases. However, the reduced availability of gas globally diminishes the fraction of AGNs in cluster centers. The surplus of X-ray AGNs identified in the outskirts of relaxed clusters may be attributed to an increased frequency of galaxy mergers, a notion that is further supported by the disturbed morphology observed in several galaxies.

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The XMM Cluster Survey analysis of the SDSS DR8 redMaPPer catalogue: implications for scatter, selection bias, and isotropy in cluster scaling relations

Cited by 10 publications

References 53 publications

Is the observable Universe consistent with the cosmological principle?

Is the observable Universe consistent with the cosmological principle?

CODEX: Role of velocity substructure in the scaling relations of galaxy clusters

AGNs in massive galaxy clusters: Role of galaxy merging, infalling groups, cluster mass, and dynamical state

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