The XXL Survey L. Active galactic nucleus contamination in galaxy clusters: Detection and cosmological impact

Abstract

X-ray observations of galaxy clusters are impacted by the presence of active galactic nuclei (AGNs) in a manner that is challenging to quantify, leading to biases in the detection and measurement of cluster properties for both astrophysics and cosmological applications. We detect and characterise clusters contaminated by central AGNs within the XXL survey footprint and provide a systematic assessment of the cosmological impact of such systems in X-ray cluster samples. We introduce a new automated class for AGN-contaminated (AC) clusters in the XXL source detection pipeline. The majority of these systems are otherwise missed by current X-ray cluster-detection methods. The AC selection is also effective in distinguishing AGN and cool-core presence using supplementary optical and infrared information. We present 33 AC objects, including 25 clusters in the redshift range, $0.14\le z\le 1.03$, and eight other sources with significantly peaked central profiles. Six of these are new confirmed clusters. We computed the missed fraction of the XXL survey, which is defined as the fraction of genuine clusters that are undetected due to their centrally peaked X-ray profiles. We report seven undetected AC clusters above $z>0.6$, in the range where X-ray cluster detection efficiency drops significantly. The missed fraction is estimated to be at the level of $5\%$ for the 50 square-degree XXL area. The impact on cosmological estimates from missed clusters is negligible for XXL, but it produces a tension of $\sim 3\sigma$ with the fiducial cosmology when considering larger survey areas. Looking towards surveys such as eROSITA and \textit{Athena}, larger areas and increased sensitivity will significantly enhance cluster detection, and therefore robust methods for characterising AGN contamination will be crucial for precise cluster cosmology, particularly in the redshift $z>1$ regime.

arXiv comment26 pages, 11 figures (33 images of AC objects presented in the appendix), 3 tables. Accepted for publication in A&A

References in corpus (50)

• Astropy: A Community Python Package for Astronomy
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Hyper Suprime-Cam SSP Survey: Overview and Survey Design
• The ROSAT Brightest Cluster Sample (BCS) - I. The compilation of the sample and the cluster log N-log S distribution
• The Northern ROSAT All-Sky (NORAS) Galaxy Cluster Survey I: X-ray Properties of Clusters Detected as Extended X-ray Sources
• Planck 2013 results. XXIX. Planck catalogue of Sunyaev-Zeldovich sources
• The Dark Energy Survey Data Release 1
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• The resolved fraction of the Cosmic X-ray Background
• The XXL Survey: I. Scientific motivations - XMM-Newton observing plan - Follow-up observations and simulation programme
• The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release
• The XMM-Newton EPIC Background: Production of Background Maps and Event Files
• The Growth of Cool Cores and Evolution of Cooling Properties in a Sample of 83 Galaxy Clusters at 0.3 < z < 1.2 Selected from the SPT-SZ Survey
• The XMM Cluster Survey: Optical analysis methodology and the first data release
• The Atacama Cosmology Telescope: The Two-Season ACTPol Sunyaev-Zel'dovich Effect Selected Cluster Catalog
• The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction
• The XXL Survey XX: The 365 cluster catalogue
• Scaling Relations and Overabundance of Massive Clusters at z>~1 from Weak-Lensing Studies with HST
• The XMM Large Scale Structure survey: The X-ray pipeline and survey selection function
• The XXL Survey. XIII. Baryon content of the bright cluster sample
• Structure Detection in Low Intensity X-Ray Images
• The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II)\\ II. Construction and Properties of the Survey
• The XXL Survey XXV. Cosmological analysis of the C1 cluster number counts
• A New RASS Galaxy Cluster Catalog with Low Contamination Extending to $z\sim 1$ in the DES Overlap Region
• The Blanco Cosmology Survey: An Optically-Selected Galaxy Cluster Catalog and a Public Release of Optical Data Products
• Distant galaxy clusters in the XMM Large Scale Structure survey
• AGN contamination of galaxy-cluster thermal X-ray emission: predictions for eRosita from cosmological simulations
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Galaxy Clusters and Groups in Disguise
• Comparison of source detection procedures for XMM-Newton images
• Enhancement of AGN in a protocluster at z=1.6
• A New Comprehensive 2-D Model of the Point Spread Functions of the XMM-Newton EPIC Telescopes : Spurious Source Suppression and Improved Positional Accuracy
• The XMM-LSS survey: the Class 1 cluster sample over the extended 11 deg${}^2$ and its spatial distribution
• The Evolution of Active Galactic Nuclei in Clusters of Galaxies from the Dark Energy Survey
• The X-CLASS survey: A catalogue of 1646 X-ray-selected galaxy clusters up to z$\sim$1.5
• A New Infrared Criterion for Selecting Active Galactic Nuclei to Lower Luminosities
• The cosmological analysis of X-ray cluster surveys: I- A new method for interpreting number counts
• XXL Survey groups and clusters in the Hyper Suprime-Cam Survey. Scaling relations between X-ray properties and weak lensing mass
• The XXL survey: XLVI. Forward cosmological analysis of the C1 cluster sample
• Deep Learning-Based Super-Resolution and De-Noising for XMM-Newton Images
• The WaZP galaxy cluster sample of the Dark Energy Survey Year 1
• The XXL survey XXXV. The role of cluster mass in AGN activity
• DES Science Portal: Computing Photometric Redshifts
• The XXL Survey XXIV. The final detection pipeline
• The XXL Survey XIX. A realistic population of simulated X-ray AGN: Comparison of models with observations
• High-redshift galaxy groups as seen by Athena/WFI
• The X-ray Variability of AGN and its Implications for Observations of Galaxy Clusters
• A Multi-wavelength Survey of AGN in Massive Clusters: AGN Distribution and Host Galaxy Properties
• Clusters of Galaxies Masquerading as X-Ray Quasars
• The XXL survey: XLII. Detection and characterization of the galaxy population of distant galaxy clusters in the XXL-N/VIDEO field: A tale of variety
• The XXL Survey: XXXIII. Chandra Constraints on the AGN Contamination of z > 1 XXL Galaxy Clusters

Cited by in corpus (1)

• XXL-HSC: Host properties of X-ray detected AGNs in XXL clusters