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Strong Lensing by Subhalos in the Dwarf Galaxy Mass Range. I. Image Separations
Stockholm University, Faculty of Science, Department of Astronomy.
Stockholm University, Faculty of Science, Department of Astronomy.
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2008 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 684, no 2, 804-810 p.Article in journal (Refereed) Published
Abstract [en]

The cold dark matter scenario predicts that a large number of dark subhalos should be located within the halo of each Milky Way-sized galaxy. One telltale signature of such dark subhalos could be additional milliarcsecond-scale image splitting of quasars previously known to be multiply imaged on arcsecond scales. Here we estimate the image separations for the subhalo density profiles favored by recent N-body simulations and compare these to the angular resolution of both existing and upcoming observational facilities. We find that the image separations produced are very sensitive to the exact subhalo density profile assumed, but in all cases they are considerably smaller than previous estimates based on the premise that subhalos can be approximated by singular isothermal spheres. Only the most optimistic subhalo models produce image separations that would be detectable with current technology, and many models produce image separations that will remain unresolved with all telescopes expected to become available in the foreseeable future. Detections of dark subhalos through image-splitting effects will therefore be far more challenging than currently believed, albeit not necessarily impossible.

Place, publisher, year, edition, pages
2008. Vol. 684, no 2, 804-810 p.
Keyword [en]
dark matter, galaxies: dwarf, galaxies: halos, gravitational lensing, quasars: general
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-16165DOI: 10.1086/590541OAI: diva2:182685
Available from: 2008-12-15 Created: 2008-12-15 Last updated: 2011-04-20Bibliographically approved
In thesis
1. Investigating the Dark Universe through Gravitational Lensing
Open this publication in new window or tab >>Investigating the Dark Universe through Gravitational Lensing
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A variety of precision observations suggest that the present universe is dominated by some unknown components, the so-called dark matter and dark energy. The distribution and properties of these components are the focus of modern cosmology and we are only beginning to understand them.

Gravitational lensing, the bending of light in the gravitational field of a massive object, is one of the predictions of the general theory of relativity. It has become an ever more important tool for investigating the dark universe, especially with recent and coming advances in observational data.

This thesis studies gravitational lensing effects on scales ranging over ten orders of magnitude to probe very different aspects of the dark universe. Implementing a matter distribution following the predictions of recent simulations, we show that microlensing by a large population of massive compact halo objects (MACHOs) is unlikely to be the source of the observed long-term variability in quasars. We study the feasibility of detecting the so far elusive galactic dark matter substructures, the so-called “missing satellites”, via millilensing in galaxies close to the line-of-sight to distant light sources. Finally, we utilise massive galaxy clusters, some of the largest structures known in the universe, as gravitational telescopes in order to detect distant supernovae, thereby gaining insight into the expansion history of the universe. We also show, how such observations can be used to put constraints on the dark matter component of these galaxy clusters.

Place, publisher, year, edition, pages
Stockholm: Department of Astronomy, Stockholm University, 2011. 67 p.
cosmology, gravitational lensing, dark matter, galaxies, galaxy clusters
National Category
Astronomy, Astrophysics and Cosmology
Research subject
urn:nbn:se:su:diva-56515 (URN)978-91-7447-281-3 (ISBN)
Public defence
2011-06-01, lecture room FD5, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:15 (English)
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Submitted. Available from: 2011-05-10 Created: 2011-04-19 Last updated: 2011-05-16Bibliographically approved

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