J/ApJ/708/661 SDSS-II SN Survey: SNe II-P standardization (D'Andrea+, 2010)
Type II-P supernovae from the SDSS-II Supernova Survey and the Standardized Candle Method. D'Andrea C.B., Sako M., Dilday B., Frieman J.A., Holtzman J., Kessler R., Konishi K., Schneider D.P., Sollerman J., Wheeler J.C., Yasuda N., Cinabro D., Jha S., Nichol R.C., Lampeitl H., Smith M., Atlee D.W., Bassett B., Castander F.J., Goobar A., Miquel R., Nordin J., Ostman L., Prieto J.L., Quimby R., Riess A.G., Stritzinger M. <Astrophys. J., 708, 661-674 (2010)> =2010ApJ...708..661D
ADC_Keywords: Supernovae ; Photometry, SDSS ; Spectroscopy ; Surveys Keywords: cosmology: observations - distance scale - supernovae: general - surveys Abstract: We apply the Standardized Candle Method (SCM) for Type II Plateau supernovae (SNe II-P), which relates the velocity of the ejecta of a SN to its luminosity during the plateau, to 15 SNe II-P discovered over the three season run of the Sloan Digital Sky Survey-II Supernova Survey. The redshifts of these SNe - 0.027<z<0.144 - cover a range hitherto sparsely sampled in the literature; in particular, our SNe II-P sample contains nearly as many SNe in the Hubble flow (z>0.01) as all of the current literature on the SCM combined. We find that the SDSS SNe have a very small intrinsic I-band dispersion (0.22mag), which can be attributed to selection effects. When the SCM is applied to the combined SDSS-plus-literature set of SNe II-P, the dispersion increases to 0.29mag, larger than the scatter for either set of SNe separately. We show that the standardization cannot be further improved by eliminating SNe with positive plateau decline rates, as proposed in Poznanski et al. (2009ApJ...694.1067P). We thoroughly examine all potential systematic effects and conclude that for the SCM to be useful for cosmology, the methods currently used to determine the FeII velocity at day 50 must be improved, and spectral templates able to encompass the intrinsic variations of Type II-P SNe will be needed. Description: The SDSS-SNS (Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN; Frieman et al. 2008AJ....135..338F) repeatedly surveyed the 300deg2 Southern Equatorial Stripe (designated stripe 82; see Stoughton et al. 2002AJ....123..485S) during the Fall seasons (September 1-November 30) of 2005-2007 using a dedicated 2.5m telescope at Apache Point Observatory, New Mexico. The SDSS-SNS spectroscopically confirmed a total of 34 SNe II-P. Our Standardized Candle Method (SCM) sample is composed of the SDSS-SNS SNe II-P that pass three cuts (see section 2.1). In the end, we find 15 of the 34 spectroscopically confirmed SNe II-P have sufficient data for the SCM analysis, and thus form our SCM sample. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 107 21 Rest-frame day 50 magnitudes of SNe II-P from the SDSS-II SN Survey (and FeII velocities for the 15 SCM sample from table 3) sn.dat 44 34 List of SNe with photometry and spectroscopy phot/* 117 34 *Individual SNe photometry files spec/* 0 73 *Individual fits spectra for the 34 confirmed Type II-P SNe from the SDSS-II
Notes on phot/*: These files contain results of the scene modelling photometry for each of the spectroscopically confirmed Type II-P supernovae from the full three season run of the SDSS supernova survey. Each file contains a header section that gives information about the particular supernova: its designation, coordinates, redshift, the derived galaxy brightness underneath the supernova as derived from the scene modelling photometry, and the foreground extinction. The header also contains a few notes on the units used. Notes on spec/*: This folder contains all spectra taken of the 34 spectroscopically confirmed Type II-P SNe from the SDSS-II Supernova Survey. Note that the SN is not necessarily visible in each spectra; for every object that was eventually identified as a SN II-P, all spectra taken are included. The name of each file is the SDSS Candidate Identification Number (CID) followed by the date the spectrum was taken in MMDDYYYY format. Each file is in the format obtained from the observers. Spectra have not been corrected for reddening and are presented in the observer frame.
See also: B/sn : Asiago Supernova Catalogue (Barbon et al., 1999-) J/A+A/526/A28 : SDSS-II supernovae NTT and NOT spectroscopy (Oestman+, 2011) J/ApJS/185/32 : First-year SDSS-II SN results (Kessler+, 2009) J/AJ/136/2306 : SDSS-II Supernova survey, 2005 (Holtzman+, 2008) J/AJ/135/348 : SDSS-II SNe survey: search and follow-up (Sako+, 2008) J/AJ/135/1766 : Sloan Digital Sky Survey-II supernova survey (Zheng+, 2008) http://sdssdp62.fnal.gov/sdsssn/snlist_confirmed_updated.php : SDSS-II SNe http://www.sdss.org/ : SDSS home page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 A6 --- SN IAU name (YYYYaa) (except flagged) (1) 7 A1 --- f_SN [a] a: SDSS-II SN number 9- 14 F6.4 --- z Redshift (2) 16- 21 F6.4 --- e_z Redshift uncertainty 23- 27 F5.2 mag Bmag Bessell B-band magnitude (Vega) (3) 29- 32 F4.2 mag e_Bmag Bmag uncertainty 34- 38 F5.2 mag Vmag Bessell V-band magnitude (Vega) (3) 40- 43 F4.2 mag e_Vmag Vmag uncertainty 45- 49 F5.2 mag Rmag Bessell R-band magnitude (Vega) (3) 51- 54 F4.2 mag e_Rmag Rmag uncertainty 56- 60 F5.2 mag Imag Bessell I-band magnitude (Vega) (3) 62- 65 F4.2 mag e_Imag Imag uncertainty 67- 71 F5.2 mag gmag SDSS g-band AB magnitude (3) 73- 76 F4.2 mag e_gmag gmag uncertainty 78- 82 F5.2 mag rmag SDSS r-band AB magnitude (3) 84- 87 F4.2 mag e_rmag rmag uncertainty 89- 93 F5.2 mag imag SDSS i-band AB magnitude (3) 95- 98 F4.2 mag e_imag imag uncertainty 100-103 I4 km/s FeIIvel ? FeII velocity (nu_FeII_) from table 3 (2) 105-107 I3 km/s e_FeIIvel ? FeIIvel uncertainty from table 3 (2)
Note (1): The 21 SNe listed here include the 15 SCM (Standardized Candle Method) sample SNe, as well as those that only fail our spectroscopy cut (described in Section 2.1). Note (2): An additional uncertainty of σpec=300km/s is added in quadrature to both the redshift z and the velocity derived from the FeII5169 absorption feature before applying the SCM to this sample. Note (3): Magnitudes listed here are derived for 50 days after the explosion, and have been both K-corrected and corrected for MW extinction along the line of sight. Bessell BVRI magnitudes are calculated in the Vega system and have been S-corrected from the observed filters; SDSS gri magnitudes are standard log10 magnitudes (not asinh, as in Holtzman et al. 2008, Cat. J/AJ/136/2306), and are in the AB system. We model the plateau as an exponential in flux space, and fold into our photometric corrections the uncertainties in observed flux, explosion epoch and redshift.
Byte-by-byte Description of file: sn.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Simbad hour of right ascension (
J2000) 4- 5 I2 min RAm Simbad minute of right ascension ( J2000) 7- 10 F4.1 s RAs Simbad second of right ascension ( J2000) 12 A1 --- DE- Simbad sign of declination ( J2000) 13- 14 I2 deg DEd Simbad degree of declination ( J2000) 16- 17 I2 arcmin DEm Simbad arcminute of declination ( J2000) 19- 20 I2 arcsec DEs Simbad arcsecond of declination ( J2000) 22- 31 A10 --- --- [SDSS-II SN] 33- 37 I5 --- SDSS-II SDSS-II number (<SDSS-II SN NNNNN> in Simbad) 39- 44 A6 --- SN IAU SN designation (YYYYaa) if any
Byte-by-byte Description of file (# headlines): phot/*
Bytes Format Units Label Explanations
1- 4 I4 --- Flag [0/1469] Photometry flags for each measurement (1) 6- 17 F12.6 d MJD Modified Julian Date of the measurement 20 I1 --- Filt [0/4] Filter in which the measurement was obtained:  corresponds to [ugriz] 23- 28 F6.3 mag mag The asinh magnitude of the supernova for this epoch and filter in the native SDSS photometric system 31- 36 F6.3 mag e_mag Error on the magnitude 39- 44 F6.3 mag e_sky Estimate of possible systematic error from uncertainty in sky determination 47- 52 F6.3 mag e_gal Estimate of possible systematic error from uncertainty in galaxy background determination 54- 63 E10.4 uJy Flux Derived flux using the SDSS/AB correction from the paper 66- 74 E9.4 uJy e_Flux Error in the flux 77- 85 E9.4 uJy e_sky2 Estimate of possible systematic error from uncertainty in sky determination in flux units 88- 96 E9.4 uJy e_gal2 Estimate of possible systematic error from uncertainty in galaxy background determination in flux units 100-101 I2 --- Npre [1/27] The number of available SDSS frames before 2005, which constrain the total brightness of the underlying galaxy 103-106 A4 --- Tel [sdss] The telescope used for the measurement, always sdss here 110-113 I4 --- run [5566/7202] The SDSS run number in which the observation was obtained 115-117 A3 --- strip [82N/82S] SDSS strip 82N or 82S
Note (1): Flag as follows: 0 = there are no lines on the measurement. >1024 = the measurement is likely bad. 0<FLAG<1024 = the measurement is likely OK, but there was some line on the frames so it was not used to constrain the galaxy background. See paper for more details.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Feb-2012
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