Lensing by substructures

M. Miranda, Ph Jetzer, A. V. Macciò

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Gravitational lenses on arcseconds scales provide a tool to probe the mass distribution in the lensing galaxies at redshift z ≈ 0.5-1.0. Image positions can be fitted using simple smooth galaxy mass models, but observed fluxes are more difficult to match. We analyze the effects of substructures in galaxy halos to explain such anomalies in the cusp and fold leasing configurations with different approaches. In the first case we use detailed numerical simulations combined with a Monte Carlo approach to compare predictions from the ACDM small scale mass function with observed flux ratios. We extended our analysis down to a mass of ≈105 M for the subhalos. Moreover, we considered extra-halos, like other galaxies surrounding the primary lens: also if we include these effects we are not able to reproduce the observed fluxes. This seems to indicate that there is no direct evidence for dark dwarf satellites from multiple imaged QSOs. In the second case we try to constrain, with a semianalytical approach, the mass and the position of a substructure by considering its effects on the flux of the images: 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. With substructures in the mass range ∼106-108 M we are able to fit quite accurately the anomalous fluxes for fold configurations.

Original languageEnglish (US)
Title of host publication21st IAP Colloquium Mass Profiles and Shapes of Cosmological Structures
Number of pages2
StatePublished - 2006
Event21st IAP Colloquium Mass Profiles and Shapes of Cosmological Structures - Paris, France
Duration: Jul 4 2005Jul 9 2005

Publication series

NameEAS Publications Series
ISSN (Print)1633-4760


Other21st IAP Colloquium Mass Profiles and Shapes of Cosmological Structures

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • General Engineering
  • Space and Planetary Science


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