First robotic monitoring of a lensed quasar: Intrinsic variability of SBS 0909+532

Abstract

To go into the details about the variability of the double quasar SBS 0909+532, we designed a monitoring programme with the 2 m Liverpool Robotic Telescope in the r Sloan filter, spanning 1.5 years from 2005 January to 2006 June. The rband light curves of the A and B components, several cross-correlation techniques and a large number of simulations (synthetic light curves) lead to a robust delay ∆t BA = − 49 ± 6 days (1σ interval) that agrees with our previous results (the B component is leading). Once the time delay and the magnitude offset are known, the magnitude-and time-shifted light curve of image A is subtracted from the light curve of image B. This difference light curve of SBS 0909+532 is consistent with zero, so any possible extrinsic signal must be very weak, i.e., the observed variability in A and B is basically due to observational noise and intrinsic signal. We then make the combined light curve and analyse its statistical properties (structure functions). The structure function of the intrinsic luminosity is fitted to predictions of simple models of two physical scenarios: accretion disc instabilities and nuclear starbursts. Although no simple model is able to accurately reproduce the observed trend, symmetric triangular flares in an accretion disc seems to be the best option to account for it.

A Consistent Picture Emerges: A Compact X-Ray Continuum Emission Region in the Gravitationally Lensed Quasar SDSS J0924+0219

“…Monitoring lenses over time addresses these problems (Kochanek 2004;Kochanek et al 2006;Goicoechea et al 2008) while simultaneously permitting time delay measurements (e.g., recent measurements by Tewes et al 2013;Eulaers et al 2013;Rathna Kumar et al 2013). In particular, the Bayesian Monte Carlo method of Kochanek (2004) enables the extraction of probability densities for the physical parameters of interest (e.g., source size, M , etc.)…”

H0from ten well-measured time delay lenses

“…For each pair of quasar images, we see that the time delays measured from the two datasets agree to within 2σ. -SBS 0909+532: for our analysis, we used only the r-band data points obtained using the Liverpool Robotic Telescope between 2005 January and 2007 January presented in Goicoechea et al (2008) and Hainline et al (2013), based on homogeneity and sampling considerations. -RX J0911.4+0551: we used the light curves presented in Hjorth et al (2002), which were made publicly available by Paraficz et al (2006).…”

“…Of the 14 remaining systems, we did not model the mass distribution for four of them for the following reasons. 8 GHz, 15 GHz ∆t AB 10.1 +1.5 −1.6 (95% CI) 10.7 ± 0.8 HE 0435−1223 (Courbin et al 2011; R ∆t AB 8.4 ± 2.1 9.8 ± 1.1 Blackburne et al 2014) ∆t AC 0.6 ± 2.3 3.1 ± 2.2 ∆t AD 14.9 ± 2.1 13.7 ± 1.0 ∆t BC −7.8 ± 0.8 −8.0 ± 1.0 ∆t BD 6.5 ± 0.7 6.2 ± 1.5 ∆t CD 14.3 ± 0.8 13.6 ± 0.8 SBS 0909+532 (Goicoechea et al 2008; r ∆t AB −50 +2 R ∆t AB 16 ± 2 7.8 ± 14.0 Q0957+561 (Shalyapin et al 2012) r, g ∆t AB 417.4 ± 0.9 420.0 ± 1.4 SDSS J1001+5027 (Rathna Kumar et al 2013) R ∆t AB 119.3 ± 3.3 119.7 ± 1.8 SDSS J1004+4112 (Fohlmeister et al 2007; R, r ∆t AB −40.6 ± 1.8 −37.2 ± 3.1 Fohlmeister et al 2008) ∆t AC −821.6 ± 2.1 −822.5 ± 7.4 ∆t BC −777.1 ± 9.2 SDSS J1029+2623 (Fohlmeister et al 2013) r ∆t A(B+C) 744 ± 10 (90% CI) 734.3 ± 3.8 HE 1104−1805 (Poindexter et al 2007) R, V ∆t AB −152.2 +2.8 …”

The Mechanism of Intrinsic Variability in Bright Gravitationally Lensed Quasars at 1 less than z less than 2

“…Second, the observed structure function included observational noise. This noise has a significant effect on the measured variations at the shortest lags and the measured slope [8].…”

“…and R 4/3 is the emission radius, e.g., [8] and references 1 The square root of the structure functions once the observational noise is properly subtracted therein. Hence, assuming that the involved scales as 2 , the expected relationship opt~1 0 UV is in clear disagreement with the observed one ( opt~ UV ).…”