A measurement of the transverse velocity of Q2237+0305

Wyithe, J. Stuart B.; Webster, R. L.; Turner, Edwin L.

doi:10.1046/j.1365-8711.1999.02844.x

Cited by 49 publications

(51 citation statements)

References 24 publications

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“…In spite of the fact that the range of typical determinations of dM/dt is not excessively broad, all the individual 1σ measurements are in agreement with no accretion, but a flow of matter of almost 1000ε M yr −1 cannot be ruled out. On the other hand, one direct constraint on v d was recently reported by Wyithe et al (1999). This group is involved in a project to interpret the QSO 2237+0305 microlensing light-curves, and as a part of the program, they derived an upper limit of v t < 500 km s −1 , where v t is the galactic transverse velocity (Ω 0 = 1, λ 0 = 0).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Determination of the properties of the central engine in microlensed QSOs

Goicoechea¹,

Alcalde²,

Mediavilla³

et al. 2002

A&A

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Abstract. We study a recently observed gravitational microlensing peak in the V-band light curve of Q2237+0305A using a relatively simple physical model, but one that is highly consistent with the data (the best-fit reduced χ 2 is very close to 1). The source quasar is assumed to be a Newtonian geometrically-thin and optically-thick accretion disk. The disk has an arbitrary orientation, and both blackbody and greybody emission spectra are considered. When the electron-photon scattering plays a role, the greybody spectrum will be a simplified version of the exact one. In our model, the microlensing variability results from the source crossing a caustic straight line. The main goal of our work is to estimate the black hole mass and the mass accretion rate in QSO 2237+0305 as well as to discuss the power and the weakness of the technique, some possible improvements, and future prospects from multifrequency monitoring of new microlensing peaks. We also put into perspective the new methodology and the results on the central engine in QSO 2237+0305. From the fitted microlensing parameters and reasonable dynamical/cosmological constraints, it is concluded that QSO 2237+0305 harbours a central massive black hole: 10 7 M < M < 6 × 10 8 M . While the information about the central dark mass is very interesting, the mass accretion rate is not so well constrained. The typical values of the disk luminosity/Eddington luminosity ratio are in the (1 − 20)ε range, where ε ≤ 1 is the emissivity relative to a blackbody and the highest L/L Edd ratio corresponds to the largest deflector motion. Therefore, in order to verify L/L Edd ≤ 1, a relatively small projected peculiar motion of the lens galaxy and a greybody emission seem to be favored.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Determination of the properties of the central engine in microlensed QSOs

Goicoechea¹,

Alcalde²,

Mediavilla³

et al. 2002

A&A

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“…The value of this "effectiveness parameter" is a ≈ 1.3 (see Wambsganss & Kundic 1993;Kundić & Wambsganss 1995, for details). Since the central velocity dispersion of the lensing galaxy in Q2237+0305 has been measured: v µlens 215 km s −1 (Foltz et al 1992), we can use that and infer an even lower value for the upper limit on the effective velocity of the bulk motion (the velocity dispersion at the location of the images could be slightly different, though): Wyithe et al (1999) presented the first determination of the effective transverse velocity of the lens galaxy in Q2237 via microlensing. Here we compare this approach to ours.…”

Section: CLmentioning

confidence: 99%

“…Q2237+0305 is the best studied quasar microlensing system. With ten years of monitoring data, Wyithe et al (1999) used the derivatives of the observed microlensing lightcurves to put limits on the lens galaxy tranverse velocity of Q2237+0305. Very recently, Kochanek (2004) developed a method for analysing microlensing lightcurves based on a χ 2 statistics which includes the transverse velocity of the source as an output parameter.…”

Section: Introductionmentioning

confidence: 99%

Limits on the transverse velocity of the lensing galaxy in Q2237+0305 from the lack of strong microlensing variability

Gil-Merino

Wambsganß

Goicoechea

et al. 2005

A&A

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Abstract. We present a method for the determination of upper limits on the transverse velocity of the lensing galaxy in the quadruple quasar system Q2237+0305, based on the lack of strong microlensing signatures in the quasar lightcurves. The limits we derive here are based on four months of high quality monitoring data, by comparing the low amplitudes of the lightcurves of the four components with extensive numerical simulations. We make use of the absence of strong variability of the components (especially components B and D) to infer that a "flat" time interval of such a length is only compatible with an effective transverse velocity of the lensing galaxy of v bulk ≤ 630 km s −1 for typical microlenses masses of M µlens = 0.1 M (or v bulk ≤ 2160 km s −1 for M µlens = 1.0 M ) at the 90% confidence level. This method may be applicable in the future to other systems.

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“…This makes possible some estimations of certain GLS characteristics, in particular, the source size [25]. For example, in case of the well-known GLS Q2237+0305 (Einstein Cross), several HAEs was observed [26][27][28] and the estimates of the source size have been obtained within different source models [16,[29][30][31][32][33][34].…”

Section: Preliminary Commentsmentioning

confidence: 99%

Analytical Methods in Gravitational Microlensing

Жданов

Alexandrov

Fedorova

et al. 2012

ISRN Astronomy and Astrophysics

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We discuss analytical results dealing with photometric and astrometric gravitational microlensing. The first two sections concern approximation methods that allow us to get solutions of the general lens equation near fold caustics and cusp points up to any prescribed accuracy. Two methods of finding approximate solutions near the fold are worked out. The results are applied to derive new corrections to total amplifications of critical source images. Analytic expressions are obtained in case of the Gaussian, power-law, and limb-darkening extended source models; here we present the first nonzero corrections to the well-known linear caustic approximation. Possibilities to distinguish different source models in observations are discussed on the basis of statistical simulations of microlensed light curves. In the next section, we discuss astrometric microlensing effects in various cases of extended sources and extended lenses, including a simple model of weak statistical microlensing by extended dark matter clumps. Random walks of a distant source image microlensed by stochastic masses are estimated. We note that the bulk motion of foreground stars induces a small apparent rotation of the extragalactic reference frame. Compact analytical relations describing the statistics of such motions are presented.

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A measurement of the transverse velocity of Q2237+0305

Cited by 49 publications

References 24 publications

Determination of the properties of the central engine in microlensed QSOs

Determination of the properties of the central engine in microlensed QSOs

Limits on the transverse velocity of the lensing galaxy in Q2237+0305 from the lack of strong microlensing variability

Analytical Methods in Gravitational Microlensing

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