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1.
SEARCH FOR LENSED SUPERNOVAE BY MASSIVE GALAXY CLUSTERS WITH THE 2.5m NORDIC OPTICAL TELESCOPE
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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Abell 1689, galaxy clusters, telescopes, lensed supernovae, strong lensing...
Ključne besede: gravitational telescopes, Abell 1689, galaxy clusters, telescopes, lensed supernovae, strong lensing
Objavljeno: 23.01.2018; Ogledov: 173; Prenosov: 0
.pdf Polno besedilo (59,07 KB)
Gradivo ima več datotek! Več...

2.
High-redshift supernova rates measured with the gravitational telescope A 1689
Tanja Petrushevska, R. Amanullah, Ariel Goobar, S. Fabbro, Joel Johansson, Tor Kjellsson, Chris Lidman, K. Paech, Johan Richard, H. Dahle, Raphael Ferretti, J.P. Kneib, M. Limousin, Jakob Nordin, V. Stanishev, 2016, izvirni znanstveni članek

Opis: Aims. We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides. Methods. Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope. Results. Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671 < z < 1.703 and magnifications in the range ∆m = −0.31 to −1.58 mag, as calculated from lensing models in the literature. Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z ∼ 3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4 ≤ z < 2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19 −0.09 ± 0.01 SNuB h 2 (SNuB ≡ 10−12 SNe L −1 ,B yr−1 ), where the error bars indicate 1σ confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10+0.13 −0.06 ± 0.02 in SNuM h 2 (SNuM ≡ 10−12 SNe M−1 yr−1 ). Furthermore, we explore the optimal future survey for improving the core-collapse supernova rate measurements at z & 2 using gravitational telescopes, and for detections with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects. Conclusions. Massive clusters can be used as gravitational telescopes to significantly expand the survey range of supernova searches, with important implications for the study of the high-z transient Universe.
Najdeno v: ključnih besedah
Povzetek najdenega: ...supernovae: general – gravitational lensing: strong – galaxies: star formation – galaxies: clusters:...
Ključne besede: supernovae: general – gravitational lensing: strong – galaxies: star formation – galaxies: clusters: individual: A 1689 – techniques: photometric
Objavljeno: 23.01.2018; Ogledov: 116; Prenosov: 0
.pdf Polno besedilo (2,64 MB)

3.
iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova
Tanja Petrushevska, S.R. Kulkarni, Rahman Amanullah, Ariel Goobar, 2017, izvirni znanstveni članek

Opis: We report the discovery of a multiply-imaged gravitationally lensed Type Ia supernova, iPTF16geu, at redshift z = 0.409. This phenomenon could be iden- tified because the light from the stellar explosion was magnified more than fifty times by the curvature of space around matter in an intervening galaxy. We used high spatial resolution observations to resolve four images of the lensed supernova, approximately 0.300 from the center of the foreground galaxy. The observations probe a physical scale of ⇠1 kiloparsec, smaller than what is typical in other studies of extragalactic gravitational lensing. The large mag- nification and symmetric image configuration implies close alignment between the line-of-sight to the supernova and the lens. The relative magnifications of the four images provide evidence for sub-structures in the lensing galaxy.
Najdeno v: ključnih besedah
Povzetek najdenega: ...lensed supernova, strong lensing, galaxy lens, multiply-lensed supernova... ...typical in other studies of extragalactic gravitational lensing. The large mag- nification and symmetric image...
Ključne besede: lensed supernova, strong lensing, galaxy lens, multiply-lensed supernova
Objavljeno: 23.01.2018; Ogledov: 160; Prenosov: 0
.pdf Polno besedilo (2,53 MB)

4.
Testing for redshift evolution of Type Ia supernovae using the strongly lensed PS1-10afx at z = 1.4
Tanja Petrushevska, Rahman Amanullah, Mattia Bulla, Markus Kromer, Raphael Ferretti, Ariel Goobar, Semeli Papadogiannakis, 2017, izvirni znanstveni članek

Opis: Context. The light from distant supernovae (SNe ) can be magnified through gravitational lensing when a foreground galaxy is located along the line of sight. This line-up allows for detailed studies of SNe at high redshift that otherwise would not be possible. Spectroscopic observations of lensed high-redshift Type Ia supernovae (SNe Ia) are of particular interest since they can be used to test for evolution of their intrinsic properties. The use of SNe Ia for probing the cosmic expansion history has proven to be an extremely powerful method for measuring cosmological parameters. However, if systematic redshift-dependent properties are found, their usefulness for future surveys could be challenged. Aims. We investigate whether the spectroscopic properties of the strongly lensed and very distant SN Ia PS1-10afx at z = 1.4, deviates from the well-studied populations of normal SNe Ia at nearby or intermediate distance. Methods. We created median spectra from nearby and intermediate-redshift spectroscopically normal SNe Ia from the literature at −5 and +1 days from light-curve maximum. We then compared these median spectra to those of PS1-10afx. Results. We do not find signs of spectral evolution in PS1-10afx. The observed deviation between PS1-10afx and the median templates are within what is found for SNe at low and intermediate redshift. There is a noticeable broad feature centred at λ ∼ 3500 Å, which is present only to a lesser extent in individual low- and intermediate-redshift SN Ia spectra. From a comparison with a recently developed explosion model, we find this feature to be dominated by iron peak elements, in particular, singly ionized cobalt and chromium.
Najdeno v: ključnih besedah
Povzetek najdenega: ...supernovae: individual: PS1-10afx – gravitational lensing: strong – supernovae: general...
Ključne besede: supernovae: individual: PS1-10afx – gravitational lensing: strong – supernovae: general
Objavljeno: 23.01.2018; Ogledov: 167; Prenosov: 0
.pdf Polno besedilo (1,00 MB)

5.
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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...also have multiple images due to the strong lensing. Of particular interest is to detect... ...thanks to the magnification boost due to lensing, can be observed, otherwise too faint to...
Ključne besede: supernovae, gravitational telescopes, galaxy clusters, lensed supernovae, strong lensing, astronomical surveys and telescopes
Objavljeno: 23.01.2018; Ogledov: 124; Prenosov: 0
.pdf Polno besedilo (28,31 MB)

6.
High-redshift supernova rates measured with the gravitational telescope A1689
Tanja Petrushevska, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Aims. We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides. Methods. Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope. Results. Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671 < z < 1.703 and magnifications in the range ∆m = −0.31 to −1.58 mag, as calculated from lensing models in the literature. Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z ∼ 3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4 ≤ z < 2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19 ± 0.01 SNuB h2 (SNuB ≡ −0.09 10−12 SNe L−1 yr−1 ), where the error bars indicate 1σ confidence intervals, statistical and systematic, respectively. The cluster rate ⊙,B normalized by the stellar mass is 0.10+0.13 ± 0.02 in SNuM h2 (SNuM ≡ 10−12 SNe M−1 yr−1). Furthermore, we explore the optimal −0.06 ⊙ future survey for improving the core-collapse supernova rate measurements at z 2 using gravitational telescopes, and for detections with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects. Conclusions. Massive clusters can be used as gravitational telescopes to significantly expand the survey range of supernova searches, with important implications for the study of the high-z transient Universe.
Najdeno v: ključnih besedah
Povzetek najdenega: ...supernova, gravitational telescope, galaxy clusters, Abell 1689, strong lensing...
Ključne besede: supernova, gravitational telescope, galaxy clusters, Abell 1689, strong lensing
Objavljeno: 26.01.2018; Ogledov: 137; Prenosov: 0
.pdf Polno besedilo (9,17 MB)

7.
Search for lensed supernovae behind the galaxy cluster Abell 1689
Tanja Petrushevska, prispevek na konferenci brez natisa

Najdeno v: ključnih besedah
Povzetek najdenega: ...lensed supernovae, supernova rates, galaxy clusters, strong lensing...
Ključne besede: lensed supernovae, supernova rates, galaxy clusters, strong lensing
Objavljeno: 26.01.2018; Ogledov: 163; Prenosov: 0
.pdf Polno besedilo (9,17 MB)

8.
Supernovae seen through gravitational telescopes
Tanja Petrushevska, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Galaxies, and clusters of galaxies, can act as gravitational lenses and magnify the light of objects behind them. The effect enables observations of very distant supernovae, that otherwise would be too faint to be detected by existing telescopes, and allows studies of the frequency and properties of these rare phenomena when the universe was young. Under the right circumstances, multiple images of the lensed supernovae can be observed, and due to the variable nature of the objects, the difference between the arrival times of the images can be measured. Since the images have taken different paths through space before reaching us, the time-differences are sensitive to the expansion rate of the universe. One class of supernovae, Type Ia, are of particular interest to detect. Their well known brightness can be used to determine the magnification, which can be used to understand the lensing systems. I will also report our discovery of the first resolved multiply-imaged gravitationally lensed supernova Type Ia.
Najdeno v: ključnih besedah
Povzetek najdenega: ...lensed supernovae, strong lensing...
Ključne besede: lensed supernovae, strong lensing
Objavljeno: 03.05.2018; Ogledov: 207; Prenosov: 0
.pdf Polno besedilo (541,15 KB)

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