J/A+A/593/A55ivo://CDS.VizieR/J/A+A/593/A55doi:10.26093/cds/vizier.35930055CDSVagnetti F.Middei R.Antonucci M.Paolillo M.Serafinelli R.2018-08-07T12:30:22Z2016-09-21T08:13:19ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiquasarsx-ray-sourcesMost investigations of the X-ray variability of active galactic nuclei (AGN) have been concentrated on the detailed analyses of individual, nearby sources. A relatively small number of studies have treated the ensemble behaviour of the more general AGN population in wider regions of the luminosity-redshift plane. We want to determine the ensemble variability properties of a rich AGN sample, called Multi-Epoch XMM Serendipitous AGN Sample (MEXSAS), extracted from the fifth release of the XMM-Newton Serendipitous Source Catalogue (XMMSSC-DR5), with redshift between 0.1 and 5, and X-ray luminosities in the 0.5-4.5keV band between 10^42^ and 10^47^erg/s. We urge caution on the use of the normalised excess variance (NXS), noting that it may lead to underestimate variability if used improperly. We use the structure function (SF), updating our previous analysis for a smaller sample. We propose a correction to the NXS variability estimator, accounting for the light curve duration in the rest frame on the basis of the knowledge of the variability behaviour gained by SF studies. We find an ensemble increase of the X-ray variability with the rest-frame time lag tau, given by tau^0.12^. We confirm an inverse dependence on the X-ray luminosity, approximately as L_X^-0.19^. We analyse the SF in different X-ray bands, finding a dependence of the variability on the frequency as nu^-0.15^, corresponding to a softer when brighter trend. In turn, this dependence allows us to parametrically correct the variability estimated in observer-frame bands to that in the rest frame, resulting in a moderate shift upwards (V-correction). Ensemble X-ray variability of AGNs is best described by the structure function. An improper use of the normalised excess variance may lead to an underestimate of the intrinsic variability, so that appropriate corrections to the data or the models must be applied to prevent these effects.2016A&A...593A..55Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/593/A55CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIX/46 : XMM-Newton Serendipitous Source Cat. 3XMM-DR5 (XMM-SSC, 2016)VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)J/A+A/536/A84 : X-ray variability of AGN (Vagnetti+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/593/A55https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/593/A55http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/593/A55https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/593/A55https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/593/A55http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/593/A55GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/593/A55/table1 (The MEXSAS sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/593/A55/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/593/A55/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/593/A55/table1?GETtext/xml+votable180.050000true4.32-1.1236110.0055555555555555565/1827 4419 4421-4425 4428 4438 6814 6/2154-2155 2227 2230 2240 4206 4298 4313-4314 4352 4403 4409 4438-4439 4488 4536 4653 4695 4748 4804 4831 4964-4965 4976 4992 5069 5074 5091 5130 5244 5305 5367 5370 5414 5417 5420 5423 5434 5469 5471 5536 5560 5570 5576 5610 5816 5857 5860 5862 5939 5945 5952 5970 5975-5976 5983-5984 6020-6021 6035 6040 6047 6051 6056 6069 6073 6075 6077 6079 6090 6096 6098 6112 6251 6337 6340 6495 6539 6560 6977 7178 7210-7211 7258-7259 7266-7267 7280-7281 7301-7303 7349 7409 7424 7426 7485 7606 8193 8195-8196 8220 8224 8271 8299 8339 8385 8675 8707 8805 8809 8843 8909 8922-8923 8927 8941 8945 8952 9036 9052 9077 9168 9192 9194 9231 9253 9287 9333 9343 9346-9347 9354 9399 9401 9428 9436 9443-9445 9468-9469 9476-9477 9512 9612-9613 9638-9639 9654 9660 9662 9672 9752 9754 9831 9837 9842 9959 9997 9999 10004 10020 10030 10116 10153 10169 10183 10189-10191 10212-10214 10255 10264-10266 10293 10306 10312 10348 10378-10379 10400-10401 10413-10414 10484 10549 10598 10601 10604-10605 10645 10653 10761 10763-10764 10769 10771-10772 10841 10856 10888 10905 10911-10912 10924-10925 10927 10977 10979-10980 10982 11026-11027 11048 11050 11063 11080 11101 11112 11127 11230 11249 11252-11253 11255 11337 11340 11347 11351 11353-11355 11365 11375 11382 11388 11391-11392 11411 11416 11424 11430 11434 11436 11461 11810 11829 11873 11875 11924 11936 12317 12405 12644 13414 17399 17497 17503 17622-17623 17671 17674-17675 17681-17683 17705 17708-17709 17716 17727 17730 17766-17767 17772-17773 17814 18009 18017 18062 18069 18084 18114 18153 18184 18206-18207 18241 18258 18365 18385 18387 18398 18431 18607 18773 18790 18794-18796 18809 18894 19027 19030 19033 19035-19036 19193 19283 19402 19424 19609 19717 19728 19730 19848 19883 19904-19905 19950 19978 19990 19996 20000 20071 20083 20209 20358 21870 23190-23191 23197 23209 25906-25907 25944 25946 25968 25972 25982 25989 25991 26000 26002 26019 26022-26023 26025 26028 26037 26039 26080 26082 26090-26091 26223 26292-26294 26300 26303 26365 26432 26561 26563 27124 27126-27127 27133 27219 27223 27225 27228 27245-27247 27428 27460 27462 27491 27714-27715 27719 27721 27730 27742 27765 27767 27772-27773 27859-27860 27862 27907 27913 27936 27941 27944-27945 27950 28015 28019 28023 28026 28029 28045 28063 28075 28127 28173 28221 28223 28249 28251 28275 28278 28281 28284 28344 28346 28356 28390 28396 28430 28449 28452 28492 28494 28516-28517 28522 28529 28534-28535 28540-28541 28583 28589 28632 28634 28636-28637 31399 31628 31662 31669 31712 32418 32424 32483 32486 32500 36765 36774 36785 36798 40958https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/593/A55?format=asciiX-raydefaultJ/A+A/593/A55/table1The MEXSAS sampleSeqSequential source numbermeta.id;meta.mainintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource 3XMM name (JHHMMSS.s+DDMMSS)meta.idcharzRedshiftsrc.redshiftfloat<fX>Average flux, 0.5-4.5keVmW.m**-2phot.flux;em.X-raydoubleNepNumber of observing epochsmeta.numberintDtrestRest-frame time intervaldtime.intervalfloatNXSNormalised excess variancestat.variancefloatNXScorrNormalised excess variance, correctedstat.variancefloatSimbadSimbad column added by the CDSmeta.ref.urlchar_RAPosition from 3XMM name (right ascension part)degpos.eq.ra;meta.main_DEPosition from 3XMM name (declination part)degpos.eq.dec;meta.main