Mass decomposition of SLACS lens galaxies in Weyl conformal gravity

Abstract

We study here, using the Mannheim-Kazanas solution of Weyl conformal theory, the mass decomposition in the representative subsample of 57 earlytype elliptical lens galaxies of the Sloan Lens Advanced Camera for Surveys (SLACS) on board the Hubble Space Telescope (HST). We begin by showing that the solution need not be an exclusive solution of conformal gravity but can also be viewed as a solution of a class of f (R) gravity theories coupled to non-linear electrodynamics thereby rendering the ensuing results more universal. Since lensing involves light bending, we shall first show that the solution adds to Schwarzschild light bending caused by the luminous mass (M * ) a positive contribution +γR contrary to the previous results in the literature, thereby resolving a long standing problem. The cause of the error is critically examined. Next, applying the expressions for light bending together with an input equating Einstein and Weyl angles, we develop a novel algorithm for separating the luminous component from the total lens mass (luminous+dark) within the Einstein radius. Our results indicate that the luminous mass estimates differ from the observed total lens masses by a linear proportionality factor across the subsample, which qualitatively agrees with the common conclusion from a number of different simulations in the literature. In quantitative detail, we observe that the ratios of luminous over total lens mass (f * ) within the Einstein radius of individual galaxies take on values near unity, many of which remarkably fall inside or just marginally outside the specified error bars obtained from a simulation based on the Bruzual-Charlot stellar population synthesis model together with the Salpeter Intitial Mass Function (IMF) favored on the ground of metallicity [Grillo et al., Astron. Astrophys. 501, 461(2009) average dark matter density ρ av of individual galaxies within their respective Einstein spheres. To our knowledge, the present approach, being truly analytic, seems to be the first of its kind attempting to provide a new decomposition scheme distinct from the simulational ones.

Exact gravitational lensing in conformal gravity and Schwarzschild–de Sitter spacetime

“…Previously, this has been done by Cutajar and Adami [38] using the deflection formulas obtained by [23,26,27]. More recently, an analysis inspired by [37] was conducted by [39]. Since we have updated these formulas to exact expressions, it would be worthwhile to revisit the observational data using Eq.…”

Ergosphere, Photon Region Structure, and the Shadow of a Rotating Charged Weyl Black Hole

“…The coefficientε ≡ c 1 in Equation ( 16), is intended to recover the cosmological constituents of the spacetime and, here, has the dimension of m −2 . Accordingly, the lapse function (15) provides the exterior geometry of the CWBH. In the adopted geometric system of units, Q and λ have the dimensions of m. For λ > Q, this spacetime allows for two horizons; an event horizon r + , and a cosmological horizon r ++ (instead of a Cauchy horizon), given by [55] r…”

“…The exterior geometry of the RCWBH is, therefore, specified by applying the lapse function (15), which provides…”

“…Along the same efforts, the fourth order theory of conformal gravity appeared as one of the alternatives to compare the theoretical results with the cosmological and astrophysical observations, and some considerable constraints have been driven. This theory was formulated by H. Weyl in 1918 [8], revived by Riegert in 1984 [9], and since then, has been applied widely to explain astrophysical phenomena (see, for example [10][11][12][13][14][15][16][17][18]).…”

Gravitational waves in conformal gravity

“…A series of dynamical solutions in CG were found in [36]. Mass decomposition of the lens galaxies of the Sloan Lens Advanced Camera for Surveys in CG was discussed in [37]. Recently it was indicated that conformal gravity can potentially test well against all astrophysical observations to date [38].…”