PHOTOMETRIC TYPE Ia SUPERNOVA CANDIDATES FROM THE THREE-YEAR SDSS-II SN SURVEY DATA

Journal Article · Sat Sep 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/738/2/162; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21584873

Sako, Masao; Connolly, Brian; Gladney, Larry ^[1]; Bassett, Bruce ^[2]; Dilday, Benjamin ^[3]; Cambell, Heather; Lampeitl, Hubert; Nichol, Robert C ^[4]; Frieman, Joshua A; Kessler, Richard ^[5]; Marriner, John ^[6]; Miquel, Ramon ^[7]; Schneider, Donald P ^[8]; Smith, Mathew ^[9]; Sollerman, Jesper ^[10]

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1. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)
2. South African Astronomical Observatory, Observatory 7935 (South Africa)
3. Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States)
4. Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)
5. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
6. Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)
7. Institut de Fisica d'Altes Energies, Universitat Autonoma de Barcelona, E-08193 Barcelona (Spain)
8. Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
9. Astrophysics, Cosmology and Gravity Centre (ACGC), Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7700 (South Africa)
10. Oskar Klein Centre, Department of Astronomy, Albaova SE-106 91 Stockholm (Sweden)

We analyze the three-year Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey data and identify a sample of 1070 photometric Type Ia supernova (SN Ia) candidates based on their multiband light curve data. This sample consists of SN candidates with no spectroscopic confirmation, with a subset of 210 candidates having spectroscopic redshifts of their host galaxies measured while the remaining 860 candidates are purely photometric in their identification. We describe a method for estimating the efficiency and purity of photometric SN Ia classification when spectroscopic confirmation of only a limited sample is available, and demonstrate that SN Ia candidates from SDSS-II can be identified photometrically with {approx}91% efficiency and with a contamination of {approx}6%. Although this is the largest uniform sample of SN candidates to date for studying photometric identification, we find that a larger spectroscopic sample of contaminating sources is required to obtain a better characterization of the background events. A Hubble diagram using SN candidates with no spectroscopic confirmation, but with host galaxy spectroscopic redshifts, yields a distance modulus dispersion that is only {approx}20%-40% larger than that of the spectroscopically confirmed SN Ia sample alone with no significant bias. A Hubble diagram with purely photometric classification and redshift-distance measurements, however, exhibits biases that require further investigation for precision cosmology.

• OSTI ID: 21584873
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 738; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
CLASSIFICATION
EFFICIENCY
ERUPTIVE VARIABLE STARS
PHOTOMETRY
RED SHIFT
STARS
SUPERNOVAE
VARIABLE STARS