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Substructures in lens galaxies: PG1115+080 and B1555+375, two fold configurations


Miranda, Marco; Jetzer, Philippe (2007). Substructures in lens galaxies: PG1115+080 and B1555+375, two fold configurations. Astrophysics and Space Science, 312(3-4):203-214.

Abstract

We study the anomalous flux ratio which is observed in some four-image lens systems, where the source lies close to a fold caustic. In this case two of the images are close to the critical curve and their flux ratio should be equal to unity, instead in several cases the observed value differs significantly. The most plausible solution is to invoke the presence of substructures, as for instance predicted by the Cold Dark Matter scenario, located near the two images. In particular, we analyze the two fold lens systems PG1115+080 and B1555+375, for which there are not yet satisfactory models which explain the observed anomalous flux ratios. We add to a smooth lens model, which reproduces well the positions of the images but not the anomalous fluxes, one or two substructures described as singular isothermal spheres. For PG1115+080 we consider a smooth model with the influence of the group of galaxies described by a SIS and a substructure with mass ∼105 M ⊙ as well as a smooth model with an external shear and one substructure with mass ∼108 M ⊙. For B1555+375 either a strong external shear or two substructures with mass ∼107 M ⊙ reproduce the data quite well

Abstract

We study the anomalous flux ratio which is observed in some four-image lens systems, where the source lies close to a fold caustic. In this case two of the images are close to the critical curve and their flux ratio should be equal to unity, instead in several cases the observed value differs significantly. The most plausible solution is to invoke the presence of substructures, as for instance predicted by the Cold Dark Matter scenario, located near the two images. In particular, we analyze the two fold lens systems PG1115+080 and B1555+375, for which there are not yet satisfactory models which explain the observed anomalous flux ratios. We add to a smooth lens model, which reproduces well the positions of the images but not the anomalous fluxes, one or two substructures described as singular isothermal spheres. For PG1115+080 we consider a smooth model with the influence of the group of galaxies described by a SIS and a substructure with mass ∼105 M ⊙ as well as a smooth model with an external shear and one substructure with mass ∼108 M ⊙. For B1555+375 either a strong external shear or two substructures with mass ∼107 M ⊙ reproduce the data quite well

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Item Type:Journal Article, refereed, original work
Communities & Collections:National licences > 142-005
Dewey Decimal Classification:Unspecified
Scopus Subject Areas:Physical Sciences > Astronomy and Astrophysics
Physical Sciences > Space and Planetary Science
Language:English
Date:29 November 2007
Deposited On:26 Nov 2018 15:30
Last Modified:15 Apr 2021 14:52
Publisher:Springer
ISSN:0004-640X
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1007/s10509-007-9677-3

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