On the evolution of mass density power-law index in strong gravitational lensing: cosmological model independent constraints [CL]


Strong gravitational lensing is a powerful cosmological tool, furnishing angular diameter distances independent of local calibrators and cosmic transparency. However, a crucial point in the strong gravitational lensing science is the knowledge of exact matter distribution of lens. Nowadays, studies have shown that slopes of density profiles of individual galaxies exhibit a non-negligible scatter from the simplest model, the singular isothermal sphere ($\rho \propto r^{-2}$), and a spherically symmetric power-law mass distribution has been assumed ($\rho \propto r^{-\gamma}$) as a generalization, including a possible time-evolution of the $\gamma$ parameter. In this work, by using strong gravitational lensing observations, SNe Ia data and the cosmic distance duality relation validity, we propose a cosmological model independent method to explore if the $\gamma$ parameter is time-dependent. As is largely known, a $\gamma$ evolution may play a crucial role on galaxy structure. We use three different parametrizations for $\gamma(z)$, namely: $\gamma(z)=\gamma_0+\gamma_1 z$, $\gamma(z)=\gamma_0+\gamma_1 z/(1+z)$ and $\gamma(z)=\gamma_0+\gamma_1 \ln(1+z)$. No significant evidence for $\gamma$ evolution was verified with present data.

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R. Holanda, S. Pereira and D. Jain
Fri, 19 May 17

Comments: 6 pages, 6 figures