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Near-IR search for lensed supernovae behind galaxy clusters. I. Observations and transient detection efficiency
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
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2009 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 507, no 1, 61-69 p.Article in journal (Refereed) Published
Abstract [en]

Context: Massive galaxy clusters at intermediate redshift can magnify the flux of distant background sources by several magnitudes.

Aims: We exploit this effect to search for lensed distant supernovae that may otherwise be too faint to be detected.

Methods: A supernova search was conducted at near infrared wavelengths using the ISAAC instrument at the VLT. The massive galaxy clusters Abell 1689, Abell 1835, and AC114 were observed for a total of 20 h to search for supernovae in gravitationally magnified background galaxies. The observations were split into individual epochs of 2 h of exposure time, separated by approximately one month. Image-subtraction techniques were used to search for transient objects with light curve properties consistent with supernovae, both in our new and archival ISAAC/VLT data. The limiting magnitude of the individual epochs was estimated by adding artificial stars to the subtracted images. Most of the epochs reach 90% detection efficiency at SZ(J) ≃ 23.8-24.0 mag (Vega).

Results: Two transient objects, both in archival images of Abell 1689 and AC114, were detected. The transient in AC114 coincides - within the position uncertainty - with an X-ray source and is likely to be a variable AGN at the cluster redshift. The transient in Abell 1689 was found at SZ = 23.24 mag, ~0.5´´away from a galaxy with photometric redshift z_gal = 0.6 ± 0.15. The light curves and the colors of the transient are consistent with a reddened type IIP supernova at redshift z = 0.59 ± 0.05. The lensing model of Abell 1689 predicts ~1.4 mag of magnification at the position of the transient, making it the most magnified supernova ever found and only the second supernova found behind a galaxy cluster. Conclusions: Our pilot survey has demonstrated the feasibility to find distant gravitationally magnified supernovae behind massive galaxy clusters. One likely supernova was found behind Abell 1689, in accordance with the expectations for this survey, as shown in an accompanying analysis paper. Based on observations made with ESO telescopes at the Paranal Observatory under program IDs 079.A-0192 and 081.A-0734.

Place, publisher, year, edition, pages
2009. Vol. 507, no 1, 61-69 p.
Keyword [en]
supernovae: general -- gravitational lensing -- methods: observational -- techniques: photometric
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:su:diva-35757DOI: 10.1051/0004-6361/200911982ISI: 000271782900012ISBN: 0004-6361 (print)OAI: oai:DiVA.org:su-35757DiVA: diva2:287974
Available from: 2010-01-20 Created: 2010-01-20 Last updated: 2017-12-12Bibliographically 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.
Keyword
cosmology, gravitational lensing, dark matter, galaxies, galaxy clusters
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
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)
Opponent
Supervisors
Note
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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Stanishev, ValleryGoobar, ArielPaech, KerstinAmanullah, RahmanJönsson, JakobLidman, ChrisMörtsell, EdvardNobili, SerenaRiehm, Teresavon Strauss, Mikael
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