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Contraintes sur la distribution de masse des galaxies par cisaillement gravitationnel

Abstract : Gravitational lensing has now become a popular tool to measure the mass distribution of structure in the universe on various scales. Recently there have been progress on mapping the mass distribution on relatively large scales using cosmic shear, and on cluster scales using the combination of strong and weak lensing. I will focuss on the study of galaxy's scale dark matter halos which become possible with high quality imaging data, from ground based telescope or space telescope. The idea is the following : observing the shapes of distant background galaxies wich have been lensed by foreground galaxies allows us to map the mass distribution of the foreground galaxies. This is called galaxy-galaxy lensing. Of course, the lensing effect is small compared to the intrinsic ellipticity distribution of galaxies, thus a statistical approach is needed; consequently, galaxy-galaxy lensing studies allow to constrain the mean properties of the halo population as a whole, and the reliability of the signal will depend on the number of foreground-background pairs. One advantage of this statistical approach is that it provides a probe of the gravitational potential of the halos of galaxies out to very large radii, where few classical methods are viable, since dynamical and hydrodynamical tracers of the potential cannot be found at this radii. I present a maximum likelihood analysis of simulated data, investigating the properties of different mass models I will introduce, and show the accuracy and robustness of constraints that can be obtained on galaxy halo properties. Then I will apply this method to study the properties of galaxies which stand in massive cluster lenses.
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Contributor : Marceau Limousin <>
Submitted on : Saturday, July 10, 2004 - 5:31:28 PM
Last modification on : Thursday, October 15, 2020 - 4:07:07 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:58:08 PM


  • HAL Id : tel-00006436, version 1



Marceau Limousin. Contraintes sur la distribution de masse des galaxies par cisaillement gravitationnel. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris-Diderot - Paris VII, 2004. Français. ⟨tel-00006436⟩



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