Optical short-time variability properties of AGN PDF
Preview Optical short-time variability properties of AGN
Optical short-time variability properties of AGN Ester Aranzana E. Körding, P. Uttley, S. Scaringi X-ray Universe 6-9 June 2017, Rome AGN variability • Characteristic time-scales (different physical mechanisms) • Light crossing time-scale ~ hours • Dynamical time-scale ~ days • Thermal time-scale ~ years • Viscous time-scale ~ tens of years McHardy (2009) Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome AGN variability • Characteristic time-scales (different physical mechanisms) • Light crossing time-scale ~ hours • Dynamical time-scale ~ days • Thermal time-scale ~ years • Viscous time-scale ~ tens of years 2.17 0.90 t M L � b BH bol ⇠ McHardy (2009) Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome AGN variability • Characteristic time-scales (different physical mechanisms) • Light crossing time-scale ~ hours • Dynamical time-scale ~ days • Thermal time-scale ~ years • Viscous time-scale ~ tens of years 2.17 0.90 t M L • Amplitude of variability � b BH bol ⇠ ⌫ 2 � (%) = P(⌫)d⌫ McHardy (2009) s ⌫ Z 1 Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome Why studying optical variability of AGN? • Long-term variability: • Short-term variability: SDSS, Palomar Green handful of selected sources Quasars, PanSTARRS with Kepler Simm et al. 2015 Mushotzy et al. 2011 Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome Why studying optical variability of AGN? Origin of rapid optical variability? ★ Jet ★ Reprocessing of X-rays ★ Disc instabilities Is there a cosmological evolution on the variability properties of the AGN? Accretion states? Variability properties associated to a certain BH mass or luminosity? Ester Aranzana E s t e r A r a n z a n aT h e o p t i c a l r m s - fl u x r e l aOtpiotinca: lf rvoamri aCbVilsit tyo p AroGpNesr t i e s o f A G N X - r a y U n i v e r s e 6 - 9 J u nNeA 2C0 2117s, tR oofm Meay 2015 Sample selection and observations with K2 275 AGN selected from the “Million Quasar Catalogue” with R > 19 (Flesch 2013) Duration: 80 days Cadence: 29.4 min Bandpass: 420-900 nm Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome Monte Carlo simulations of power spectra Uttley et al. 2002 Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome Monte Carlo simulations of power spectra Uttley et al. 2002 Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome Monte Carlo simulations of power spectra e g l r a c S m b - P o L obs Uttley et al. 2002 Ester Aranzana Optical variability properties of AGN X-ray Universe 6-9 June 2017, Rome
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