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Light propagation in inhomogeneous universes. III. Distributions of image separations
Martel H.a, Premadi P.b, Matzner R.a
a Department of Astronomy, University of Texas, United States
b Department of Astronomy, Bosscha Observatory, Bandung Institute of Technology, Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]Using an analytical model, we compute the distribution of image separations resulting from gravitational lensing of distant sources, for seven COAE-normalized cold dark matter models with various combinations of Ω0 and λ0. Our model assumes that multiple imaging results from strong lensing by individual galaxies. We model galaxies as nonsingular isothermal spheres, whose parameters are functions of the luminosity and morphological type, and take into account the finite angular size of the sources. Our model neglects the contribution of the background matter distribution to lensing and assumes that lensing is entirely caused by galaxies. To test the validity of this assumption, we performed a series of ray-tracing experiments to study the effect of the background matter on the distribution of image separations. Our results are the following: (1) The presence of the background matter tends to increase the image separations produced by lensing galaxies, making the distributions of image separations wider. However, this effect is rather small and independent of the cosmological model. (2) Simulations with galaxies and background matter often produce a secondary peak in the distribution of image separations at large separations. This peak does not appear when the background matter is excluded from the simulations. (3) The effect of the background matter on the magnification distribution is negligible in low-density universes (Ω0 = 0.2) with small density contrast (σg = 0.4), but becomes very important as Ω0 and σ8 increase, resulting in a significant widening of the distribution. (4) Multiple imaging is caused primarily by early-type galaxies (elliptical and S0), with a negligible contribution from spiral galaxies. (5) Our analytical model, which has only two free parameters, is in good agreement with the results of ray-tracing experiments, successfully reproducing the distributions of image separations, and also the multiple-imaging probability, for all cosmological models considered. (6) The analytical model predicts that the distributions of image separations are virtually indistinguishable for flat, cosmological-constant models with different values of Ω0. (7) For models with no cosmological constant, the distributions of image separations do depend upon Ω0, but this dependence is weak. We conclude that while the number of multiple-imaged sources can put strong constraints on the cosmological parameters, the distribution of image separations does not constrain the cosmological models in any significant way and mostly provides constraints on the structure of the galaxies responsible for lensing.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Cosmology: theory,Gravitational lensing[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1086/339569[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]