J/A+A/636/A15ivo://CDS.VizieR/J/A+A/636/A15doi:10.26093/cds/vizier.36360015CDSMigkas K.Schellenberger G.Reiprich T.H.Pacaud F.Ramos-ceja M.E.,Lovisari L.2021-03-23T12:15:38Z2020-07-22T14:13:48ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxy-clustersx-ray-sourcesThe 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 (L_X_-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 D_L_, 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 L_X_-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 L_X_-T relation heavily depends on the direction of the sky, which is consistent with previous studies. Strong anisotropies are detected at a>=4{sigma} confidence level toward the Galactic coordinates (l, b)~(280{deg}, -20{deg}), 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 10^5^ 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 (~5{sigma}), toward (l, b)~(303{deg}, -27{deg}), which is in very good agreement with other cosmological probes. The maximum variation of D_L_ 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.2020A&A...636A..15Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/636/A15CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/534/A109 : MCXC Meta-Catalogue X-ray galaxy Clusters (Piffaretti+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/636/A15https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/636/A15http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/636/A15https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/636/A15https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/636/A15http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/636/A15GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/636/A15/tablec1 (Properties of the 313 clusters used in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/636/A15/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/636/A15/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/636/A15/tablec1?GETtext/xml+votable180.050000true194.952916727.98055560.0055555555555555566/50 87 206-207 306 361 929 986 1006 2227 2251 2432 4394 5099 5305 5327 5373 5524 5536 5881 5931 6017 6088 6223 6337 6609 6611 7004 7026 7242 7768 8196 8220 8223 8264 8268 8271 8520 8526 8575 8648 8788 8823 8919 8963 9036 9047 9050 9072 9168 9287 9354 9366 9468 9476 9506 9508 9543 9583 9776 9997 10180 10182 10271 10311-10312 10318 10379 10527 10664 10717 11080 11287 11591 11626 11809 11846 12121 12642 12664 15085 16030 16410-16411 16434 16492 16510 16526 16543 16609 16642 16713 16806 16953 16959 17084 17124 17141 17237 17300 17387 17452 17457 17662 17745 18009 18016 18168 18184 18324 18566 18584-18585 18598 18607 18622 18635 18742 18939 19097 19130 19204 19314 19451 19501 19608 19941 19993 20021 20029 20083 20302 20335 20355 20361 20481 20494 20507 20624 20642 20669 20707 21064 21073 21156 21169 21387 21977 22545 22577 22722 22792 22972 23097 23306 23451 24622 24637 24822 24848 24853 24943 24951 25042 25302 25478 25675 25682 25769 25852 25981 26037 26135 26188-26189 26208 26302 26313 26563 26690 26746 26770 26785 27081 27224 27428 27486 27595 27652 27660 27676 27742 27760 28005 28181 28220 28249 28414 28430 28663 30946 31121 31288 31509 31537 32362 32500 32503 32693 32746 32798 32907 33235 33433 33614 33628 33649 33894 34159 34161 34229 34442-34443 34461 34480 34496 34805 34910 35055 35985 36144 38852 38858 38973 39067-39068 39079 39577 39658 40777 40803 40987 43433 43451 43503 43627 43706 43830 43836-43838 43849 43891 43938-43939 43941 43948 43950 43977 44008 44017 44108 44502 44554 44802 45044 45242 45253 45421 45506 45542-45543 45562 45754 45893 45984 45997 46020 46237 46244 46255 46441 46474 46484 46540 46548 46652 46687 46763 46855 46889 46892 46911 47016 47188 47207 47358 47368 47386 47573 48258 48323 48344 48456 48479 48489 48639 48688 48735 48738https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/636/A15?format=asciiX-raydefaultJ/A+A/636/A15/tablec1Properties of the 313 clusters used in this workSimbadNameSimbad column added by the CDSmeta.idcharzRedshiftsrc.redshiftfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster namemeta.id;meta.maincharNote[* ] Note (1)meta.notecharGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latfloatTTemperature within 0.2-9.5R500keVphys.temperaturefloatE_TError on T, upper valuekeVstat.error;stat.maxfloate_TError on T, lower valuekeVstat.errorfloatLXX-ray luminosity within R500 for the 0.1-2.4keV energy range1e+35Wphys.luminosity;em.X-rayfloate_LXError on LX%stat.errorfloatFXX-ray flux 10-15W/m21e-15W.m**-2phot.flux;em.X-rayfloatNHtotNeutral + molecular hydrogen column density1e+20cm**-2phys.columnDensityfloatZMetal abundance within 0.2-0.5R500phys.abund.ZfloatE_ZError on Z, upper valuephys.abund.Z;stat.maxfloate_ZError on Z, lower valuephys.abund.Z;stat.minfloatInstInstrument used for analysisinstr.setupchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main