Short time-scale optical variability properties of the largest AGN sample observed with Kepler/K2

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dc.contributor.authorAranzana E
dc.contributor.authorKörding E
dc.contributor.authorUttley P
dc.contributor.authorScaringi S
dc.contributor.authorBloemen S
dc.date.accessioned2018-12-10T22:30:01Z
dc.date.available2018-12-10T22:30:01Z
dc.date.issued2018en
dc.date.updated2018-10-31T19:42:52Z
dc.description.abstract© 2017 The Authors. We 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 bymeans 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 6 × 10-6-10-4 Hz varies from 1to10 per cent with an average of 1.7 per cent.We explore correlations between the variability amplitude and key parameters of theAGN, 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.en
dc.identifier.doihttps://doi.org/10.1093/mnras/sty413
dc.identifier.issn0035-8711
dc.identifier.issn1365-2966
dc.identifier.urihttp://hdl.handle.net/10092/16321
dc.language.isoen
dc.subjectaccretion, accretion discsen
dc.subjectgalaxies: activeen
dc.subjectquasars: generalen
dc.subjectquasars: super-massive black holesen
dc.subject.anzsrcField of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences::020102 - Astronomical and Space Instrumentationen
dc.subject.anzsrcFields of Research::51 - Physical sciences::5101 - Astronomical sciences::510104 - Galactic astronomyen
dc.subject.anzsrcField of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences::020106 - High Energy Astrophysics; Cosmic Raysen
dc.titleShort time-scale optical variability properties of the largest AGN sample observed with Kepler/K2en
dc.typeJournal Articleen
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