Photometric monitoring of gravitational lenses with the nordic optical telescope

Florentin-Nielsen, R.; Teuber, J.; Knain, Erik; Stabell, R.

doi:10.1007/3-540-55797-0_82

Cited by 5 publications

(10 citation statements)

References 6 publications

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“…The first time delay for the gravitational lens Q0957+561 was measured in 1984 (Florentin-Nielsen 1984), since then more than 11 time delay lenses have been found, including 7 systems with a good quality of the astrometric data and 2 systems with serious problems (Kochanek & Schechter 2003). It would be very interesting if those debatable systems can be explained in the framework of TeVe S. However, we emphasize that the measurement of time delay is controversial.…”

Section: Discussionmentioning

confidence: 99%

Gravitational Lensing in TeVe S

Chiu¹,

Ko²,

Tian³

2006

Gravitation and Astrophysics

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Since Bekenstein's (2004) creation of his Tensor-Vector-Scalar theory (TeVe S), the Modified Newtonian dynamics (MOND) paradigm has been redeemed from the embarrassment of lacking a relativistic version. One primary success of TeVe S is that it provides an enhancement of gravitational lensing, which could not be achieved by other MONDian theories. Following Bekenstein's work, we investigate the phenomena of gravitational lensing including deflection angles, lens equations and time delay. We find that the deflection angle would maintain its value while the distance of closest approach vary in the MOND regime. We also use the deflection angle law to derive magnification and investigate microlensing light curves. We find that the difference in the magnification of the two images in the point mass model is not a constant such as in GR. Besides, microlensing light curves could deviate significantly from GR in the deep MOND regime. Furthermore, the scalar field, which is introduced to enhance the deflection angle in TeVe S, contributes a negative effect on the potential time delay. Unfortunately this phenomenon is unmeasurable in lensing systems where we can only observe the time delay between two images for a given source. However, this measurable time delay offers another constraint on the mass ratio of the dark matter and MOND scenarios, which in general differs from that given by the deflection angle. In other words, for a lensing system, if two masses, m gN and m gM , are mutually alternatives for the deflection angles in their own paradigm, regarding the time delay they are in general in an exclusive relation.

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Section: Discussionmentioning

confidence: 99%

Gravitational Lensing in TeVe S

Chiu¹,

Ko²,

Tian³

2006

Gravitation and Astrophysics

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“…However, it was found to be a very challenging measurement to make. Optical (Lloyd 1981;Keel 1982;Florentin-Nielsen 1984;Schild & Cholfin 1986;Vanderriest et al 1989;Schild & Thomson 1995) and radio monitoring programs produced extensive data, but analyses with a host of sophisticated techniques (see, e.g., Press, Rybicki & Hewitt 1992a, 1992bPelt et al 1994Pelt et al , 1996 could not resolve the conflict between groups obtaining delays near 400 days and those finding delays close to 540 days. Only recently has an optical detection of a sharp event in the light curve of each image resulted in a precise determination (∆τ = 417 ± 3 days, Kundić et al 1997), confirming the short value of the delay first obtained by Schild & Cholfin (1986).…”

Section: Introductionmentioning

confidence: 99%

A Reassessment of the Data and Models of the Gravitational Lens Q0957+561

Barkana

Lehár

Falco

et al. 1999

ApJ

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We examine models of the mass distribution for the first known case of gravitational lensing. Several new sets of constraints are used, based on recent observations. We remodel the VLBI observations of the radio cores and jets in the two images of Q0957+561, showing that the previously derived positions and uncertainties were incorrect. We use as additional constraints the candidate lensed pairs of galaxies discovered recently with the Hubble Space Telescope. We explore a wider range of lens models than before, and find that the Hubble constant is not tightly constrained once elliptical lens models are considered. We also discuss the systematic uncertainties caused by the cluster containing the lens galaxy. We conclude that additional observations of the candidate lensed galaxies as well as direct measurements of the cluster mass profile are needed before a useful value of the Hubble constant can be derived from this lens.

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“…As had already been shown by Refsdal (1966), a value for the Hubble constant which does not rely on the steps of the local distance ladder may be determined from the time delay between the di erent images of the same variable source in such gravitationally lensed systems. The QSO 0957+561 system is the only one where a fairly accurate, although not uncontested, value for the time delay has been obtained (e.g., Florentin-Nielsen 1984;Press, Rybicky, & Hewitt 1992;Pelt et al 1994). However, as was shown rst by Borgeest & Refsdal (1984) and later elaborated by e.g., Falco, Gorenstein, & Shapiro (1991) and Kochanek (1991), a determination of the Hubble constant will not only require a reliable value for the time delay between the two quasar images, but also a well-constrained model for the lensing mass distribution.…”

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confidence: 99%

Deep imaging of the double quasar QSO 0957+561: New constraints on H[SUB]0[/SUB]

Dahle¹,

Maddox²,

Lilje³

1994

ApJ

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In this Letter we present new results from extremely deep, high-resolution images of the eld around the double quasar QSO 0957+561. A possible gravitational arc system near the double quasar has recently been reported, which, if real, would set strong constraints on determinations of the Hubble constant from the time delay in the double quasar. We nd that both the morphology and the colors of the claimed arc systems suggest that they are chance alignments of three and two di erent objects, and not gravitationally lensed arcs. Hence, the constraints on H 0 -determinations from the arcs are not valid. Also, a small group of galaxies at z = 0:5 near the line-of-sight which was required to have a very large mass in the physically interesting arc models, is most likely insigni cant.From our deep images we are able to use weak lensing of faint background galaxies in the eld to map the gravitational potential in the main cluster. This sets new constraints on determinations of H 0 . We nd that the Hubble constant is constrained to be less than 70 kms 1 Mpc 1 , if the time delay between the two images of the QSO is equal to or larger than 1.1 years.

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Photometric monitoring of gravitational lenses with the nordic optical telescope

Cited by 5 publications

References 6 publications

Gravitational Lensing in TeVe S

Gravitational Lensing in TeVe S

A Reassessment of the Data and Models of the Gravitational Lens Q0957+561

Deep imaging of the double quasar QSO 0957+561: New constraints on H[SUB]0[/SUB]

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