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Abstract: Through gravitational lensing, galaxy clusters can magnify supernovae (SNe) and thereby create multiple images of the same SN. This enables measurements of cosmological parameters (primarily the Hubble constant), which will be increasingly important in the context of upcoming surveys from the Nancy Grace Roman Space Telescope ( Roman ) and Vera C. Rubin Observatory. We study the prospects of detecting strongly lensed supernovae in cluster fiels with Roman 's High Latitude Time Domain Survey (HLTDS) and the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). We employed two approaches: one focusing on known multiply imaged galaxies (arcs) behind cluster fields, along with the SN rates specific to those galaxies (arc-specific), while the second is based on the expected number of lensed SNe exploding in a given volume behind a galaxy cluster (volumetric). We collected all the clusters in the literature that feature a) a well-constrained lens model and b) multiply imaged galaxies behind clusters with high-quality data for the multiply imaged galaxies behind clusters. This allowed us to determine the supernova rate for each galaxy. We provide predictions for 46 clusters visible to the Vera C. Rubin Observatory, as well as for 9 observable by Roman ’s HLTDS, depending on whether the clusters fall within the survey’s observing field. We predict that the number of multiply imaged SNe discovered by LSST in its first three years is $3.95 ± 0.89$ from the first approach or $4.94±1.02$ from the second. Based on the current proposed observing strategy for the HLTDS, which specifies the requirements on galactic and ecliptic latitudes, the expected number of multiply imaged supernovae ranges from $0.38 ± 0.15$ to $5.2 ± 2.2$, depending on the specific cluster observed. However, the exact fields to be targeted remain a matter of discussion. We conclude that LSST offers great prospects for detecting multiply imaged SNe. If adequate follow-up campaigns are conducted, these capabilities will enable measurements of cosmological parameters independent of conventional probes. These predictions are effectively lower limits, as we only considered the most massive and well-studied clusters in the present work. Here, we provide a recommendation for HLTDS observing field selection, namely: either MACS J0553.4-3342 or Abell 1758a should be observed by the survey to maximize the number of potential multiply imaged SN discoveries.
Keywords: supernovae, gravitational lensing
Published in RUNG: 14.05.2025; Views: 435; Downloads: 6
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Abstract: Abstract Strong gravitational lensing magnifies the light from a background source, allowing us to study these sources in detail. Here, we study the spectra of a z = 1.95 lensed Type Ia supernova SN Encore for its brightest Image A, taken 39 days apart. We infer the spectral age with template matching using the supernova identification (SNID) software and find the spectra to be at 29.0 ±5.0 and 37.4 ±2.8 rest-frame days post maximum respectively, consistent with separation in the observer frame after accounting for time-dilation. Since SNe Ia measure dark energy properties by providing relative distances between low- and high-z SNe, it is important to test for evolution of spectroscopic properties. Comparing the spectra to composite low-z SN Ia spectra, we find strong evidence for similarity between the local sample and SN Encore. The line velocities of common SN Ia spectral lines, Si II 6355 and Ca II NIR triplet are consistent with the distribution for the low-z sample as well as other lensed SNe Ia, e.g. iPTF16geu (z = 0.409)and SN H0pe (z = 1.78). The consistency between the low-z sample and lensed SNe at high-z suggests no obvious cosmic evolution demonstrating their using as high-z distance indicators, though this needs to be confirmed/refuted via a larger sample. We also find that the spectra of SN Encore match the predictions for explosion models very well. With future large samples of lensed SNe Ia e.g. with the Vera C. Rubin Observatory, spectra at such late phases will be important to distinguish between different explosion scenarios.
Keywords: Encore, supernovae
Published in RUNG: 29.10.2024; Views: 1274; Downloads: 8
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Keywords: supernova, strong lensing, cosmology, Hubble constant, James Webb Space Telescope
Published in RUNG: 21.05.2024; Views: 2022; Downloads: 13
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Abstract: I will present our current efforts to enable the use of strongly lensed supernovae behind galaxy clusters as powerful tools to tackle several open questions in astrophysics and cosmology. As a preparatory task, we are collecting all available gravitational telescopes into a database, and estimating the properties of all reported multiply-imaged galaxies behind clusters. We are building a tool that will enable accurate estimates of cluster-lensed supernova yields for a given survey. In addition, we are developing the methods to extract the cosmological parameters from cluster-lensed supernovae in the Rubin and Roman data.
Keywords: supernova, gravitational lensing, Vera Rubin Observatory, Roman Space telescope, LSST, Hubble constant
Published in RUNG: 09.11.2022; Views: 2734; Downloads: 9
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Abstract: In the event of a release of toxic gas in the center of London, emergency services personnel would need to determine quickly the extent of the area contaminated. The transport of pollutants by turbulent flow within the complex streets and building architecture of London, United Kingdom, is not straightforward, and we might wonder whether it is at all possible to make a scientifically reasoned decision. Here, we describe recent progress from a major U.K. project, Dispersion of Air Pollution and its Penetration into the Local Environment (DAPPLE; information online at www.dapple.org.uk). In DAPPLE, we focus on the movement of airborne pollutants in cities by developing a greater understanding of atmospheric flow and dispersion within urban street networks. In particular, we carried out full-scale dispersion experiments in central London from 2003 through 2008 to address the extent of the dispersion of tracers following their release at street level. These measurements complemented previous studies because 1) our focus was on dispersion within the first kilometer from the source, when most of the material was expected to remain within the street network rather than being mixed into the boundary layer aloft; 2) measurements were made under a wide variety of meteorological conditions; and 3) central London represents a European, rather than North American, city geometry. Interpretation of the results from the full-scale experiments was supported by extensive numerical and wind tunnel modeling, which allowed more detailed analysis under idealized and controlled conditions. In this article, we review the full-scale DAPPLE methodologies and show early results from the analysis of the 2007 field campaign data.
Keywords: Air quality, Atmospheric thermodynamics, Dispersions, Experiments
Published in RUNG: 18.07.2019; Views: 5596; Downloads: 0
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