J/MNRAS/476/2501ivo://CDS.VizieR/J/MNRAS/476/2501doi:10.26093/cds/vizier.74762501CDSAranzana E.Kording E.Uttley P.Scaringi S.Bloemen S.2024-08-18T20:18:29Z2021-05-31T13:38:28ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiquasarsredshiftedWe present the first short time-scale (~ hours to days) optical variability study of a large sample of active galactic nuclei (AGNs) observed with the Kepler/K2 mission. The sample contains 252 AGN observed over four campaigns with ~30 min cadence selected from the Million Quasar Catalogue with R magnitude <19. We performed time series analysis to determine their variability properties by means of the power spectral densities (PSDs) and applied Monte Carlo techniques to find the best model parameters that fit the observed power spectra. A power-law model is sufficient to describe all the PSDs of our sample. A variety of power-law slopes were found indicating that there is not a universal slope for all AGNs. We find that the rest-frame amplitude variability in the frequency range of 6x10^-6^-10^-4^Hz varies from 1 to 10 per cent with an average of 1.7 per cent. We explore correlations between the variability amplitude and key parameters of the AGN, finding a significant correlation of rest-frame short-term variability amplitude with redshift. We attribute this effect to the known 'bluer when brighter' variability of quasars combined with the fixed bandpass of Kepler data. This study also enables us to distinguish between Seyferts and blazars and confirm AGN candidates. For our study, we have compared results obtained from light curves extracted using different aperture sizes and with and without detrending. We find that limited detrending of the optimal photometric precision light curve is the best approach, although some systematic effects still remain present.2018MNRAS.476.2501Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/476/2501CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)VII/283 : The Million Quasars (Milliquas) catalog (6.3) (Flesch, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/476/2501https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/476/2501http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/476/2501https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/476/2501https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/476/2501http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/476/2501GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/476/2501/tableb1 (Parameters for all the MQ AGN analysed in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/476/2501/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/476/2501/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/476/2501/tableb1?GETtext/xml+votable180.050000true174.5331-5.38050.0055555555555555565/4634 4653 4665 6772 6920 6/18437 18458 18466 18496 18498 18520 18522 18532 18540 18544 18586 18588 18590-18591 18605 18610 18616 18620-18621 18625 18627 18630-18632 18635-18637 18642 18648-18649 18652 18656-18657 18664 23995 24003 24019 24027 24042-24043 24047 24058-24059 24063 24336 24339 24341-24343 24384-24385 24387 24391 24400-24401 25535 25577 25579 25582 25586-25587 25592 25595-25596 26901-26903 26906 26909-26910 26932 26935 26943-26944 26946 26955 26966 26969 26974-26978 26983 26985 26990 26993 26995 26999 27004-27006 27025 27029 27031 27072 27074-27077 27080-27081 27084 27087 27093 27096-27097 27099 27101-27103 27109 27120 27123 27654 27661 27684 27686 27689-27690 27692 27695 27706 27778-27782 27784 27787 27792 30733 44307 44356 44378 44390-44391 44406-44407 44412-44413 48500 48503 48597https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/476/2501?format=asciidefaultJ/MNRAS/476/2501/tableb1Parameters for all the MQ AGN analysed in this workTypeType of AGN (2)src.classcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPICEPIC numbermeta.id;meta.mainlongn_EPIC[*] Note on EPIC (1)meta.notecharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainb'magb' magnitude (2)magphot.mag;em.opt.Bfloatr'magr' magnitude (2)magphot.mag;em.opt.RfloatzRedshift (2)src.redshiftfloatbetaoptNegative power-law index of the simulated PSD for the 'optimal' aperturemeta.code;spect.indexfloatE_betaoptError on betaopt (upper value)stat.error;stat.maxfloate_betaoptError on betaopt (lower value)stat.errorfloatbetaPRF9Negative power-law index of the simulated PSD for the PRF aperturemeta.code;spect.indexfloatE_betaPRF9Error on betaPRF9 (upper value)stat.error;stat.maxfloate_betaPRF9Error on betaPRF9 (lower value)stat.errorfloatbetadetNegative power-law index of the simulated PSD for the 'optimal' detrended light curvesmeta.code;spect.indexfloatE_betadetError on betadet (upper value)stat.error;stat.maxfloate_betadetError on betadet (lower value)stat.errorfloatNormBest normalisationmeta.notefloatNoisePoisson noise level obtained in the minimisation%instr.det.noisefloatProbAcceptance probability for the model%statfloatsigmaobs? Fractional rms measured in the observed power spectra%stat.errorfloatnullablesigmalitFractional rms measured in the simulated power spectra%stat.errorfloatsigmarestfitRest-frame fractional rms%stat.stdev;instr.det.noise;arith.ratiofloate_sigmarestfitRms uncertainty on sigmarestfit%stat.errorfloatLbolEstimated bolometric luminosityphys.luminosityfloatSimbadSimbad column added by the CDSmeta.ref.urlchar