Near‐Infrared Imaging Spectrophotometry of the Gravitational Mirage Q2237+0305

Nadeau, Daniel; Racine, R.; Doyon, René; Arboit, Geneviève

doi:10.1086/308054

Cited by 5 publications

(4 citation statements)

References 28 publications

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“…12, we have plotted the magnification factor -expressed as a magnitude difference -as a function of the inverse wavelength. It shows a remarkably tight wavelength dependence strikingly similar to that found by Nadeau et al (1999) for Q2237+0305. This suggests that HE 2149−2745 presently suffers a chromatic microlensing event similar (although of much longer duration) to the 1991 high-magnification event in Q2237+0305 and which was interpreted -on the basis of its colour dependenceas evidence for the thermal accretion disk model as the source of UV-visible continuum emission in quasars (cf.…”

Section: Microlensingsupporting

confidence: 77%

“…This suggests that HE 2149−2745 presently suffers a chromatic microlensing event similar (although of much longer duration) to the 1991 high-magnification event in Q2237+0305 and which was interpreted -on the basis of its colour dependenceas evidence for the thermal accretion disk model as the source of UV-visible continuum emission in quasars (cf. Nadeau et al 1999). Fig.…”

Section: Microlensingmentioning

confidence: 99%

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An optical time-delay for the lensed BAL quasar HE 2149-2745

Burud

Courbin

Magain

et al. 2002

A&A

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Abstract. We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE 2149−2745. The data, obtained with the 1.5 m Danish Telescope (ESO-La Silla) between October 1998 and December 2000, are the first from a long-term project aimed at monitoring selected lensed quasars in the Southern Hemisphere. A time delay of 103±12 days is determined from the light curves. In addition, VLT/FORS1 spectra of HE 2149−2745 are deconvolved in order to obtain the spectrum of the faint lensing galaxy, free of any contamination by the bright nearby two quasar images. By cross-correlating the spectrum with galaxy-templates we obtain a tentative redshift estimate of z = 0.495 ± 0.01. Adopting this redshift, a Ω = 0.3, Λ = 0.7 cosmology, and a chosen analytical lens model, our time-delay measurement yields a Hubble constant of H0 = 66 ± 8 km s −1 Mpc −1 (1σ error) with an estimated systematic error of ±3 km s −1 Mpc −1 . Using non-parametric models yields H0 = 65 ± 8 km s(1σ error) and confirms that the lens exhibits a very dense/concentrated mass profile. Finally, we note, as in other cases, that the flux ratio between the two quasar components is wavelength dependent. While the flux ratio in the broad emission lines -equal to 3.7 -remains constant with wavelength, the continuum of the brighter component is bluer. Although the data do not rule out extinction of one quasar image relative to the other as a possible explanation, the effect could also be produced by differential microlensing by stars in the lensing galaxy.

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Section: Microlensingsupporting

confidence: 77%

Section: Microlensingmentioning

confidence: 99%

An optical time-delay for the lensed BAL quasar HE 2149-2745

Burud

Courbin

Magain

et al. 2002

A&A

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“…Due to its very convenient configuration, it is one of the best investigated GLSs. It has been continuously monitored by a number of groups from 1992-2005 (Rix et al 1992;Falco et al 1996;Oestensen et al 1996;Blanton et al 1998;Bliokh et al 1999;Nadeau et al 1999;Wozniak et al 2000;Alcalde et al 2002;Schmidt et al 2002). Significant microlensing-induced brightness peaks on lightcurves of quasar images were detected in this system (see, e.g., Wozniak et al 2000;Alcalde et al 2002;Moreau et al 2005).…”

Section: Introductionmentioning

confidence: 96%

Q2237+0305 in X-rays: spectra and variability with XMM-Newton

Fedorova

Жданов

Vignali

et al. 2008

A&A

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Aims. X-ray observations of gravitationally lensed quasars may allow us to probe the inner structure of the central engine of a quasar. Observations of Q2237+0305 (Einstein Cross) in X-rays may be used to constrain the inner structure of the X-ray emitting source. Methods. Here we analyze the XMM-Newton observation of the quasar in the gravitational lens system Q2237+0305 taken during 2002. Combined spectra of the four images of the quasar in this system were extracted and modelled with a power-law model. Statistical analysis was used to test the variability of the total flux. Results. The total X-ray flux from all the images of this quadruple gravitational lens system is 6 × 10 −13 erg/(cm 2 s) in the range 0.2-10 keV, showing no significant X-ray spectral variability during almost 42 ks of the observation time. Fitting of the cleaned source spectrum yields a photon power-law index of Γ = 1.82−0.08 . The X-ray lightcurves obtained after background subtraction are compatible with the hypothesis of a stationary flux from the source.

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“…Different authors have made some attempts to detect chromatic microlensing and use it with different scopes. However, in many cases the detection of chromatic microlensing was rather ambiguous, since in general it is not easy to disentangle this effect from others with similar observational signatures (Wisotzki et al 1993;Nadeau et al 1999;Wucknitz et al 2003;Nakos et al 2005). The first significant applications of chromatic microlensing appeared in a very recent work of Poindexter et al (2008).…”

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confidence: 99%

Detection of Chromatic Microlensing in Q 2237 + 0305 A

Mosquera

Muñoz

Mediavilla

2009

ApJ

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We present narrowband images of the gravitational lens system Q 2237+0305 made with the Nordic Optical Telescope in eight different filters covering the wavelength interval 3510-8130 Å. Using point-spread function photometry fitting we have derived the difference in magnitude versus wavelength between the four images of Q 2237+0305. At λ = 4110 Å, the wavelength range covered by the Strömgren-v filter coincides with the position and width of the CIV emission line. This allows us to determine the existence of microlensing in the continuum and not in the emission lines for two images of the quasar. Moreover, the brightness of image A shows a significant variation with wavelength which can only be explained as consequence of chromatic microlensing. To perform a complete analysis of this chromatic event our observations were used together with Optical Gravitational Lensing Experiment light curves. Both data sets cannot be reproduced by the simple phenomenology described under the caustic crossing approximation; using more realistic representations of microlensing at high optical depth, we found solutions consistent with simple thin disk models (r s ∝ λ 4/3 ); however, other accretion disk size-wavelength relationships also lead to good solutions. New chromatic events from the ongoing narrow band photometric monitoring of Q 2237+0305 are needed to accurately constrain the physical properties of the accretion disk for this system.

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Near‐Infrared Imaging Spectrophotometry of the Gravitational Mirage Q2237+0305

Cited by 5 publications

References 28 publications

An optical time-delay for the lensed BAL quasar HE 2149-2745

An optical time-delay for the lensed BAL quasar HE 2149-2745

Q2237+0305 in X-rays: spectra and variability with XMM-Newton

Detection of Chromatic Microlensing in Q 2237 + 0305 A

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