41. Prospects for lensed supernovae behind galaxy clusters with the James Webb Space TelescopeTanja Petrushevska, 2018, published scientific conference contribution abstract Abstract: 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. I will also show the expectations
of search campaigns that can be conducted with future facilities, such as the James Webb
Space Telescope (JWST) or the Wide-Field Infrared Survey Telescope (WFIRST).
Keywords: Strong lensing, Hubble constant, measuring expansion history with time delays, lensed supernovae
Published in RUNG: 09.07.2018; Views: 3646; Downloads: 139
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42. Searching for supernovae in the multiply-imaged galaxies behind the gravitational telescope A370Tanja Petrushevska, Ariel Goobar, D. J. Lagattuta, R. Amanullah, Laura Hangard, S. Fabbro, C. Lindman, K. Paech, J. Richard, J.P. Kneib, 2017, original scientific article Abstract: Aims. Strong lensing by massive galaxy clusters can provide magnification of the flux and even multiple images of the galaxies that lie behind them. This phenomenon facilitates observations of high-redshift supernovae (SNe) that would otherwise remain undetected. Type Ia supernovae (SNe Ia) detections are of particular interest because of their standard brightness, since they can be used to improve either cluster lensing models or cosmological parameter measurements.
Methods. We present a ground-based, near-infrared search for lensed SNe behind the galaxy cluster Abell 370. Our survey was based on 15 epochs of J-band observations with the HAWK-I instrument on the Very Large Telescope (VLT). We use Hubble Space Telescope (HST) photometry to infer the global properties of the multiply-imaged galaxies. Using a recently published lensing model of Abell 370, we also present the predicted magnifications and time delays between the images.
Results. In our survey, we did not discover any live SNe from the 13 lensed galaxies with 47 multiple images behind Abell 370. This is consistent with the expectation of 0.09 ± 0.02 SNe calculated based on the measured star formation rate. We compare the expectations of discovering strongly lensed SNe in our survey and that performed with HST during the Hubble Frontier Fields (HFF) programme. We also show the expectations of search campaigns that can be conducted with future facilities, such as the James Webb Space Telescope (JWST) or the Wide-Field Infrared Survey Telescope (WFIRST). We show that the NIRCam instrument aboard the JWST will be sensitive to most SN multiple images in the strongly lensed galaxies and thus will be able to measure their time delays if observations are scheduled accordingly.
Keywords: gravitational lensing: strong / supernovae: general / galaxies: clusters: individual: A 370
Published in RUNG: 28.06.2018; Views: 3656; Downloads: 142
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43. Supernovae seen through gravitational telescopesTanja Petrushevska, 2018, published scientific conference contribution abstract (invited lecture) Abstract: 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.
Keywords: lensed supernovae, strong lensing
Published in RUNG: 03.05.2018; Views: 3354; Downloads: 0
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45. PASSERBY BECOME SUPERNOVA HUNTERS IN KUNGSTRÄDGÅRDENTanja Petrushevska, S. Papadogiannakis, Emir Karamehmetoglu, 2015, other performed works Abstract: Fysik i Kungsträdgården is one of the major outreach events in Stockholm where scientists have the chance to show their research. This year the supernova group at the OKC invited the public to look for supernovae with us using the intermediate Palomar (Transient) Factory (iPTF) collaboration telescope in Palomar, California, U.S.A. Due to the time difference between Stockholm and California, we were able to look at live images as they were taken from the telescope, to search for new transient objects such as supernovae. The event was successful, bringing a lot of people from the park in central Stockholm to come and search with us.
Keywords: science outreach, supernova hunting for the public
Published in RUNG: 09.02.2018; Views: 3793; Downloads: 0
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46. Supernovae seen through gravitational telescopesTanja Petrushevska, 2017, other performed works Abstract: 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.
Keywords: lensed supernovae
Published in RUNG: 06.02.2018; Views: 3012; Downloads: 0
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48. SUMMER SCHOOL AT FYSIKUMTanja Petrushevska, other performed works Abstract: This summer, for two weeks, 120 high school students (out of 750 applicants) had the opportunity to taste how research is done at Stockholm University. The students worked in small groups under the supervision of doctoral students in chemistry, physics, biology and geology. At the Physics department, the two PhD students Tanja Petrushevska and Seméli Papadogiannakis offered a project that involved supernovae and their host galaxies.
Keywords: summer school for high school students in astrophysics
Published in RUNG: 06.02.2018; Views: 3183; Downloads: 0
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49. PM SPECIAL – ALLDELES NY UPPTÄCKT INOM SUPERNOVOR OCH GRAVITATIONSLINSNINGTanja Petrushevska, Katarina Bendtz, other performed works Abstract: I dagarna offentliggjordes att astrofysikerna på (iPTF) Intermediate Palomar Transient Factory detekterat en supernova typ 1a som vars ljus just nu böjs av en galax. Fenomenet kallas ”gravitational lensing” och är en effekt av att rumtiden kröks av massiva objekt, som vi diskuterade i Professor Magenta avsnitt om maskhål. Tanja Petrushevska är doktorand på Stockholms universitet och medlem av iPTF. Hon och de andra i iPTF skriver just nu på artikeln om upptäckten som hon berättar mer om i detta PM special!
Keywords: interview, astrophysics outreach
Published in RUNG: 06.02.2018; Views: 3372; Downloads: 0
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