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Strong Lensing by Subhalos in the Dwarf-galaxy-mass Range. II. Detection Probabilities
Stockholm University, Faculty of Science, Department of Astronomy.
Stockholm University, Faculty of Science, Department of Astronomy.
Stockholm University, Faculty of Science, Department of Physics.
2009 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 700, no 2, 1552-1558 p.Article in journal (Refereed) Published
Abstract [en]

The dark halo substructures predicted by current cold dark matter simulations may in principle be detectable through strong-lensing image-splitting of quasars on small angular scales (0.01 arcsec or below). Here, we estimate the overall probabilities for lensing by substructures in a host halo closely aligned to the line of sight to a background quasar. Under the assumption that the quasar can be approximated as a point source, the optical depth for strong gravitational lensing by subhalos typically turns out to be very small (τ < 0.01), contrary to previous claims. We therefore conclude that it is currently not feasible to use this strategy to put the simulation predictions for the dark matter subhalo population to the test. However, if one assumes the source to be spatially extended, as is the case for a quasar observed at radio wavelengths, there is a reasonable probability for witnessing substructure lensing effects even at rather large projected distances from the host galaxy, provided that the angular resolution is sufficient. While multiply imaged, radio-loud quasars would be the best targets for unambiguously detecting dark matter subhalos, even singly imaged radio quasars might be useful for setting upper limits on the abundance and central surface mass density of subhalos.

Place, publisher, year, edition, pages
2009. Vol. 700, no 2, 1552-1558 p.
Keyword [en]
dark matter, galaxies: halos, gravitational lensing, quasars: general
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-35755DOI: 10.1088/0004-637X/700/2/1552ISI: 000268098100052ISBN: 0004-637XOAI: diva2:287973
Available from: 2010-01-20 Created: 2010-01-20 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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Riehm, TeresaZackrisson, ErikMörtsell, Edvard
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