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Title: TWO SNe Ia AT REDSHIFT ∼2: IMPROVED CLASSIFICATION AND REDSHIFT DETERMINATION WITH MEDIUM-BAND INFRARED IMAGING

We present two supernovae (SNe) discovered with the Hubble Space Telescope (HST) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, an HST multi-cycle treasury program. We classify both objects as SNe Ia and find redshifts of z = 1.80 ± 0.02 and 2.26{sup +0.02}{sub −0.10}, the latter of which is the highest redshift SN Ia yet seen. Using light curve fitting we determine luminosity distances and find that both objects are consistent with a standard ΛCDM cosmological model. These SNe were observed using the HST Wide Field Camera 3 infrared detector, with imaging in both wide- and medium-band filters. We demonstrate that the classification and redshift estimates are significantly improved by the inclusion of single-epoch medium-band observations. This medium-band imaging approximates a very low resolution spectrum (λ/Δλ ≲ 100) which can isolate broad spectral absorption features that differentiate SNe Ia from their most common core collapse cousins. This medium-band method is also insensitive to dust extinction and (unlike grism spectroscopy) it is not affected by contamination from the SN host galaxy or other nearby sources. As such, it can provide a more efficient—though less precise—alternative to IR spectroscopy for high-z SNe.
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ; ;  [6] ;  [7] ;  [8]
  1. Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States)
  2. Department of Physics, The University of Chicago, Chicago, IL 60637 (United States)
  3. Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States)
  4. Instituto de Astrofísica de Andalucía (CSIC), E-18080 Granada (Spain)
  5. Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States)
  6. Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)
  7. Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)
  8. Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)
Publication Date:
OSTI Identifier:
22520010
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 150; Journal Issue: 5; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABSORPTION SPECTROSCOPY; APPROXIMATIONS; CAMERAS; COSMIC DUST; COSMOLOGICAL MODELS; COSMOLOGY; DIAGRAMS; GALAXIES; GRAVITATIONAL COLLAPSE; INFRARED SPECTRA; LUMINOSITY; RED SHIFT; SUPERNOVAE; TELESCOPES; VISIBLE RADIATION