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High redshift supernova rates measured with a gravitational telescope
Tanja Petrushevska, 2015, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Supernovae (SNe) are one the most energetic phenomena in the Universe and have been extensively used for astrophysical and cosmological applications. For example, type Ia SNe as distance indicators tools have revealed the accelerating expansion of the universe, while core-collapse (CC) being directly related to the death of massive stars, they trace the star formation history. One of the challenges of SN research is the measurements of the SN rates, particularly at high-z where not many measurements exist. Possible approach to this problem is to use the magnification power of gravitational telescopes such as galaxy clusters. I will present our ground based near-infrared/optical search for gravitationally magnified supernovae behind the galaxy cluster A1689. Our search resulted in the discovery of five highly magnified candidates at high-z classified as CC SNe. We measure the first volumetric CC SN rates.
Ključne besede: supernova rates, gravitational telescopes, galaxy clusters
Objavljeno v RUNG: 26.01.2018; Ogledov: 2959; Prenosov: 0
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Survey with gravitational telescope to measure high redshift supernova rates
Tanja Petrushevska, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: supernova rates, high-redshift universe, gravitational telescopes, galaxy clusters
Objavljeno v RUNG: 26.01.2018; Ogledov: 3049; Prenosov: 0
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Supernovae seen through gravitational telescopes
Tanja Petrushevska, 2017, doktorska disertacija

Opis: Gravitational lenses such as galaxies and galaxy clusters, can magnify the flux of background galaxies. These galaxies at high redshift can host supernovae (SNe) which, thanks to the magnification boost due to lensing, can be observed, otherwise too faint to be detected by current telescopes. Under the right circumstances, the background galaxies may also have multiple images due to the strong lensing. Of particular interest is to detect lensed supernovae of type Ia (SNe Ia), because of their standard brightness. They could help improve lensing models and, if multiple images are observed, the Hubble constant can be measured independently. In this thesis, we use galaxy clusters as gravitational telescopes to search for lensed SNe at high redshift. We performed ground-based, near-infrared and optical search campaigns towards the massive clusters Abell 1689 and 370, which are among the most powerful gravitational telescopes known. Our search resulted in the discovery of five photometrically classified, core- collapse SNe at redshifts of 0.671 < z < 1.703 with significant magnification from the cluster. Owing to the power of the lensing cluster, we calculated the volumetric core-collapse SN rates for 0.4  z < 2.9, and find good agreement with previous estimates and predictions from cosmic star formation history. During our survey, we also discovered two SNe Ia in A1689 cluster members, which allowed us to determine the cluster Ia rate. Furthermore, we discuss the expectations of finding lensed SNe at high redshift in simulated search campaigns that can be conducted with upcoming ground- and space-based telescopes. Magnification from a galaxy lens also allows for detailed studies of the SN properties at high redshift that otherwise would not be possible. Spec- troscopic observations of lensed high-redshift SNe Ia are of particular interest since they can be used to test for evolution of the standard candle nature of these objects. However, if systematic redshift-dependent properties are found, their utility for future surveys could be challenged. We investigate whether the properties of the strongly lensed and very distant SN Ia PS1- 10afx at z = 1.4, deviates from the well-studied nearby and intermediate populations of normal SNe Ia. In other study, we report the discovery of the first resolved multiply-imaged gravitationally lensed SN Ia.
Ključne besede: supernovae, gravitational telescopes, galaxy clusters, lensed supernovae, strong lensing, astronomical surveys and telescopes
Objavljeno v RUNG: 23.01.2018; Ogledov: 3514; Prenosov: 0
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Tanja Petrushevska, 2013, objavljeni znanstveni prispevek na konferenci

Opis: We shortly present here the ongoing project by the Stockholm supernova group about the search of high-z supernovae with the ALFOSC camera at the Nordic Optical Telescope by using galaxy clusters as gravitational telescope.
Ključne besede: gravitational telescopes, Abell 1689, galaxy clusters, telescopes, lensed supernovae, strong lensing
Objavljeno v RUNG: 23.01.2018; Ogledov: 3398; Prenosov: 0
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