Gravitational Lensing in TeVe S

Abstract

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.

Testing MOND over a Wide Acceleration Range in X-Ray Ellipticals

“…, which was shown in many previous studies [5,9,[18][19][20][21] to perform well in the range of x values I cover here. The fact that ν 1 is not compatible with solar system constraints for very large y (y > 10 6 ) is of no concern here, since I use this form only up to y ∼ 20 (as in all the above references).…”

“…They conclude that, as a rule, "the gas is at least so far out of equilibrium that it does not retain any information about the shape of the potential, and that X-ray-derived radial mass profiles may be in error by factors of order unity". 5 This view is strengthened by the work of Ref. [24], and the recent [25].…”

“…[4] claim meaningful (albeit small) tension between the strong-lensing, MOND masses, and the stellar masses they deduce in the central, high-acceleration regions of several ellipticals, while Ref. [5] claim success for the MOND predictions applying the same technique to a larger sample, including that of Ref. [4] (see also Refs.…”

Mass of galaxy lenses in modified gravity: Any need for dark mass?

“…However, all of these work above are non-relativistic approximation of TeVeS. In a conference paper, [18] also showed the lens data from CASTLES and SLACS catalog are consistent with TeVeS, but they did not show the details.…”