Browsing by Author "Challis, P."

Now showing 1 - 5 of 5
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    First Cosmology Results using Supernovae Ia from the Dark Energy Survey : Survey Overview, Performance, and Supernova Spectroscopy
    (2020) Smith, M.; D'Andrea, C. B.; Sullivan, M.; Moller, A.; Nichol, R. C.; Thomas, R. C.; Kim, A. G.; Sako, M.; Castander, F. J.; Clocchiatti, Alejandro; Filippenko, A. V.; Foley, R. J.; Galbany, L.; González Gaitan, S.; Kasai, E.; Kirshner, R. P.; Lidman, C.; Scolnic, D.; Brout, D.; Davis, T. M.; Gupta, R. R.; Hinton, S. R.; Kessler, R.; Lasker, J.; Macaulay, E.; Wolf, R. C.; Zhang, B.; Asorey, J.; Avelino, A.; Bassett, B. A.; Calcino, J.; Carollo, D.; Casas, R.; Challis, P.; Childress, M.; Crawford, S.; Frohmaier, C.; Glazebrook, K.; Goldstein, D. A.; Graham, M. L.; Hoormann, J. K.; Kuehn, K.; Lewis, G. F.; Mandel, K. S.; Morganson, E.; Muthukrishna, D.; Nugent, P.; Pan, Y. C.; Pursiainen, M.; Sharp, R.
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    First cosmology results using Type Ia supernova from the Dark Energy Survey: simulations to correct supernova distance biases
    (2019) Kessler, R.; Brout, D.; D'Andrea, C. B.; Davis, T. M.; Hinton, S. R.; Kim, A. G.; Lasker, J.; Lidman, C.; Macaulay, E.; Moeller, A.; Sako, M.; Scolnic, D.; Smith, M.; Sullivan, M.; Zhang, B.; Andersen, P.; Asorey, J.; Avelino, A.; Calcino, J.; Carollo, D.; Challis, P.; Childress, M.; Clocchiatti, A.; Crawford, S.; Filippenko, A. V.; Foley, R. J.; Glazebrook, K.; Hoormann, J. K.; Kasai, E.; Kirshner, R. P.; Lewis, G. F.; Mandel, K. S.; March, M.; Morganson, E.; Muthukrishna, D.; Nugent, P.; Pan, Y. -C.; Sommer, N. E.; Swann, E.; Thomas, R. C.; Tucker, B. E.; Uddin, S. A.; Abbott, T. M. C.; Allam, S.; Annis, J.; Avila, S.; Banerji, M.; Bechtol, K.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Carnero Rosell, A.; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Crocce, M.; da Costa, L. N.; Davis, C.; De Vicente, J.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Flaugher, B.; Fosalba, P.; Frieman, J.; Garcia-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Hartley, W. G.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Johnson, M. W. G.; Johnson, M. D.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; Marshall, J. L.; Martini, P.; Menanteau, F.; Miller, C. J.; Miquel, R.; Nord, B.; Plazas, A. A.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Serrano, S.; Sevilla-Noarbe, I.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Walker, A. R.; Zhang, Y.
    We describe catalogue-level simulations of Type Ia supernova (SN Ia) light curves in the Dark Energy Survey Supernova Program (DES-SN) and in low-redshift samples from the Center for Astrophysics (CfA) and the Carnegie Supernova Project (CSP). These simulations are used to model biases from selection effects and light-curve analysis and to determine bias corrections for SN Ia distance moduli that are used to measure cosmological parameters. To generate realistic light curves, the simulation uses a detailed SN Ia model, incorporates information from observations (point spread function, sky noise, zero-point), and uses summary information (e.g. detection efficiency versus signal-to-noise ratio) based on 10 000 fake SN light curves whose fluxes were overlaid on images and processed with our analysis pipelines. The quality of the simulation is illustrated by predicting distributions observed in the data. Averaging within redshift bins, we find distance modulus biases up to 0.05 mag over the redshift ranges of the low-z and DES-SN samples. For individual events, particularly those with extreme red or blue colour, distance biases can reach 0.4 mag. Therefore, accurately determining bias corrections is critical for precision measurements of cosmological parameters. Files used to make these corrections are available at https://des.ncsa.illinois.edu/releases/sn.
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    HIGH-AMPLITUDE δ-SCUTIS IN THE LARGE MAGELLANIC CLOUD
    (2010) Garg, A.; Cook, K. H.; Nikolaev, S.; Huber, M. E.; Rest, A.; Becker, A. C.; Challis, P.; Clocchiatti, A.; Miknaitis, G.; Minniti, D.; Morelli, L.; Olsen, K.; Prieto, J. L.; Suntzeff, N. B.; Welch, D. L.; Wood-Vasey, W. M.
    We present 2323 high-amplitude delta-Scuti (HADS) candidates discovered in the Large Magellanic Cloud by the SuperMACHO survey (Rest et al.). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, we find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. We also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax.
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    LIGHT. CURVES. OF. 213 TYPE. Ia SUPERNOVAE. FROM. THE. ESSENCE. SURVEY
    (2016) Narayan, G.; Rest, A.; Tucker, B.; Foley, R.; Wood, W.; Challis, P.; Stubbs, C.; Kirshner, R.; Aguilera, C.; Clocchiatti, Alejandro; Becker, A.; Blondin, S.; Covarrubias, R.; Damke, G.; Davis, T.; Filippenko, A.
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    Supernova 2011D in UGC 2498
    (2011) Narla, A.; Cenko, S. B.; Li, W.; Filippenko, A. V.; Howerton, S.; Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Prieto, J. L.; Catelan, Marcio; Beshore, E. C.; Larson, S. M.; Christensen, E.; Marion, G. H.; Challis, P.; Berlind, P.
    Via public images from the Catalina Sky Survey (CSS). 2011 UT R.A. (2000.0) Decl. Mag. Offset Observers Jan. 5.09 3 02 14.58 +17 20 58.9 18.2 33".8 E, 14".7 N CSS Jan. 6.30 3 02 14.53 +17 20 58.3 18.2 34".4 E, 14".8 N KAIT Additional magnitudes for 2011D: 2010 Dec. 8.32 UT, [19.3 (KAIT); 10.19, [19.4 (CSS); 2011 Jan. 7.21, 18.2 (KAIT); 8.13, 17.8 (S. Howerton, remotely with the LB-1 0.6-m telescope near Rodeo, NM, U.S.A.). Drake notes that the presumed host galaxy, UGC 2498, has redshift z = 0.0231. G. H. Marion and P. Challis, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report that a spectrum (range 340-740 nm) was obtained of 2011D on Jan. 8 UT by P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+ FAST). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2011D is a type-IIb supernova a few days before maximum light....