2017/05/31 by R. F. L. Holanda, S. H. Pereira, Deepak Jain
Physics and Astronomy · #Astronomy #Astrophysics #Cosmology #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Gravitation #Gravitational lens #Gravitational lensing formalism #Physics #Power law #Redshift #Stellar, planetary, and galactic studies #Strong gravitational lensing #Supernova #Type (biology) #Velocity dispersion #astro-ph.CO #gr-qc
paper · pdf · doi:10.1093/mnras/stx1791
published as MNRAS 471, 3079 (2017) · 11 pages, 5 figures, 1 table, text revised and new analysis included. Accepted for publication in MNRAS
arxiv created 2017/07/12 · openalex publication_date 2017/07/14 · openalex created_date 2017/07/21 · arxiv updated 2017/08/16 · openalex updated_date 2026/08/05
In this work, by using strong gravitational lensing (SGL) observations along with Type Ia Supernovae (Union2.1) and gamma-ray burst data (GRBs), we propose a new method to study a possible redshift evolution of γ(z), the mass density power-law index of strong gravitational lensing systems. In this analysis, we assume the validity of cosmic distance duality relation and the flat universe. In order to explore the γ(z) behaviour, three different parametrizations are considered, namely: (P1) γ(zl) = γ0 + γ1zl; (P2) γ(zl) = γ0 + γ1zl/(1 + zl); and (P3) γ(zl) = γ0 + γ1ln (1 + zl), where zl corresponds to lens redshift. If γ0 = 2 and γ1 = 0, the singular isothermal sphere model is recovered. Our method is performed on SGL sub-samples defined by different lens redshifts and velocity dispersions. For the former case, the results are in full agreement with each other, while a 1σ tension between the sub-samples with low (≤250 km s−1) and high (>250 km s−1) velocity dispersions was obtained on the (γ0–γ1) plane. By considering the complete SGL sample, we obtain γ0 ≈ 2 and γ1 ≈ 0 within 1σ c.l. for all γ(z) parametrizations. However, we find the following best-fitting values of γ1: −0.085; −0.16; and −0.12 for P1, P2 and P3 parametrizations, respectively, suggesting a mild evolution for γ(z). By repeating the analysis with Type Ia Supernovae from Joint Light Analysis compilation, GRBs and SGL systems this mild evolution is reinforced.