Keck Mid‐Infrared Imaging of QSO 2237+0305

Agol, Eric; Jones, B.; Blaes, Omer

doi:10.1086/317847

Cited by 63 publications

(104 citation statements)

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“…In particular the magnitude difference as a function of wavelength for the epoch HJD 2454001 (Figure 1(c)) is flat given our errors of the order of ∼0.1 mag. This suggests a smaller differential extinction than the estimates of Agol et al (2000), although we cannot rule out fortuitous cancellations of color variations due to extinction by chromatic microlensing effects. Finding chromatic microlensing during this period of observations is not a surprise, since the Optical Gravitational Lensing Experiment V-band continuum data (Woźniak et al 2000) shows significant brightness variations in the three independent magnitude differences at this time.…”

Section: Observations and Data Analysiscontrasting

confidence: 62%

Structure of the Accretion Disk in the Lensed Quasar Q2237+0305 From Multi-Epoch and Multi-Wavelength Narrowband Photometry

Muñoz

Vives-Arias

Mosquera

et al. 2016

ApJ

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We present estimates for the size and the logarithmic slope of the disk temperature profile of the lensed quasar Q2237+0305, independent of the component velocities. These estimates are based on six epochs of multiwavelength narrowband images from the Nordic Optical Telescope. For each pair of lensed images and each photometric band, we determine the microlensing amplitude and chromaticity using pre-existing mid-IR photometry to define the baseline for no microlensing magnification. A statistical comparison of the combined microlensing data (6 epochs×5 narrow bands×6 image pairs) with simulations based on microlensing magnification maps gives Bayesian estimates for the half-light radius oflt-day, and p=0.95±0.33 for the exponent of the logarithmic temperature profile µ -T R p 1 . This size estimate is in good agreement with most recent studies. Other works based on the study of single microlensing events predict smaller sizes, but could be statistically biased by focusing on high-magnification events.

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Section: Observations and Data Analysiscontrasting

confidence: 62%

Structure of the Accretion Disk in the Lensed Quasar Q2237+0305 From Multi-Epoch and Multi-Wavelength Narrowband Photometry

Muñoz

Vives-Arias

Mosquera

et al. 2016

ApJ

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“…According to the macromodel by Schmidt et al (1998), rather well confirmed by the observations in emission lines (Fitte & Adam 1994;Racine 1992;Lewis et al 1998;Saust 1994), and in the IR spectral range (Nadeau et al 1991;Agol et al 2000), where no microlensing effects are expected, the A, B and D components must be almost equally amplified, with flux ratios of 0.25, 0.27 and 0.32 respectively. The C component is expected to have the lowest macroamplification factor by this model, a flux ratio of 0.15 is predicted for it.…”

Section: Variations Of Color In Q2237+0305mentioning

confidence: 56%

“…By this time, a great amount of observations of Q2237+0305 in spectral ranges other than visual continuum exists -VLA observations at 20 cm and 3.6 cm (Falco et al 1996), observations in the near and mid-IR (Nadeau et al 1991;Agol et al 2000), and in the quasar emission lines (Fitte & Adam 1994;Racine 1992;De Robertis & Yee 1988;Lewis et al 1998;Saust 1994). The observed magnitudes of the components have been found to be almost unaffected by microlensing in these spectral ranges, which indicates that much larger quasar features radiate in IR and in the radio, as well as in the emission lines, compared to the optical continuum.…”

Section: Introductionmentioning

confidence: 99%

Color effects associated with the 1999 microlensing brightness peaks in gravitationally lensed quasar Q2237+0305

Vakulik¹,

Schild

Dudinov³

et al. 2004

A&A

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Abstract. We present photometry of the Q2237+0305 gravitational lens system in VRI spectral bands with the 1.5-m telescope of the high-altitude Maidanak observatory in 1995−2000. The time interval includes the epoch of the dramatic brightness peaks discovered previously in the A and C image components (Wozniak et al. 2000a,b). By good luck three nights of observation in 1999 were almost at the time of the strong brightness peak of image C, and approximately in the middle of the ascending slope of the brightness peak of image A. Having reached its brightness maximum at the very end of June 1999, the C component had changed its (V − I) color from 0.3 m to 0.12 m since August 1998, and from 0.56 m to 0.12 m since August 1997. It was the bluest component in the system in 1998 and 1999, but by October 2000 that was no longer the case. We do not know the color of the A component exactly at its brightness peak, but we do know that it became 0.47 m brighter in R and 0.15 m bluer in (V − R) between August 1998 and August 2000, about three months before the peak. More intensive monitoring of Q2237+0305 in July-October 2000, made on a nearly daily basis, did not reveal rapid (night-to-night and intranight) brightness variations of the components during this time period, exceeding the photometry error bars. Rather slow changes of magnitudes of the components were observed, in particular, nearly synchronous 0.08 m fading of B and C components, and 0.05 m brightening of D in the R band during July 23−October 7, 2000, while the B component had become the faintest in all filters by the end of this time period. The behavior of the colors of the components was analyzed on the basis of all our VRI observations, made in 1995−2000 on Maidanak. A qualitative tendency of the components to become bluer as their brightness increases, noted in our previous works, was confirmed quantitatively. A correlation between the color variations and variations of magnitudes of the components is demonstrated to be significant and reaches 0.75 for ∆(V − I) vs. ∆R, with a regression line slope of 0.33± 0.08 for these quantities. A plot of (V − I) vs. (V − R) shows the components settled in a cluster, stretchng along a line with a slope of 1.31 ± 0.14. Both slopes are noticeably less steep than those expected if a standard galactic interstellar reddening law were responsible for the differences between the colors of images and their variations over time. We attribute the brightness and color changes to microlensing of the quasar's structure, which we conclude to be more compact at shorter wavelengths, as predicted by most quasar models featuring an energizing central source.

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“…The optical data were taken from Wozniak et al (2000), and corrected for extinction. The analysis of the 1999 data is described in Agol et al (2000). The 2000 data had Poisson errors since the pattern noise was eliminated.…”

Section: Observationsmentioning

confidence: 99%