SNfactory status and current results

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					  Nearby SNe Ia
spectrophotometry
 SNfactory status and current results
         CRAL / IPNL / LPNHE - France
               LBNL / Yale - US




        Rui Pereira - LPNHE Paris
       43rd Rencontres de Moriond
             16 March 2008
                                       SNfactory
       •        Built to tackle one of the biggest sources of statistical and
                systematic uncertainties on the cosmological analysis using high-
                redshift SNe: the nearby SNe sample


                       no local
                                       with local
            wconst




Linder 06                         Ωm                                            Conley AAS08


   •        Aims for a large spectroscopic sample (~200) of well-calibrated,
            well-sampled SNe Ia in the z = 0.03-0.08 range
                       SNfactory
•   New observational paradigm:
    synthesised photometry from
    multi-epoch spectral sequences

•   SNe search
    •   wide field survey using the
        QUEST-II camera (Mt. Palomar)

•   Spectroscopic followup
    •   Univ. Hawaii 2.2m (Mauna Kea)

    •   SuperNova Integral Field
        Spectrograph

    •   remote observation / 3 nights per
        week
                      SuperNova Integral Field
                       Spectrograph (SNIFS)
       •    2 channel 15x15 micro-lenses IFU
            (3200-10000 Å)

           •   225 simultaneous spectra from different
               points of the field (6”x6’’)

           •   absolute flux calibration on photometric
               nights using standard stars




                                                                             Y
                                                                           AR
                                                                    IN
                                                                IM
                                                                EL
                                                               PR
                                                         0.3        λ (Å) [x1e4]   1.0
(C. Buton poster)
               SuperNova Integral Field
                Spectrograph (SNIFS)
•   2k x 4k CCD imager (4.5’x9’)

    •   multifilter for probing different atmospheric
        extinction contributions

    •   simultaneous observation of the field around the
        SN - secondary stars

    •   relative flux calibration on non-photometric nights




          ÷                 =

                                               relative atmospheric attenuation
    Spectrophotometry concept

•   spectral time series




                             Y
                           AR
                       IN
                   IM
                 EL
              PR
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P
 Spectrophotometry concept
     Y
  A R
IN
       L IM
    R E
         P


              •   one spectrum per point / night
              •   synthesisable on any filter
              •   K-correction-free lightcurves +
                  spectral features
          SNfactory status
•   120 objects followed with more than 7 epochs

•   ~ 1900 SNe Ia spectra (3200 - 10000 Å)

•   2/3 of open shutter time on object followup

•   “maximum luminosity” attained during the spring of 2007

                   1200h                          120

               800h
              SNfactory status
•   quick analysis of the sample
    •   phase estimation from the
        acquisition lightcurves
PR                  PR
     EL               EL
       IM                  IM
            IN               IN
              AR                  AR
                Y                   Y


PR                  PR
     EL               EL
       IM                  IM
            IN               IN
              AR                  AR
                Y                   Y
                                        SALT2 fits




PR                  PR
     EL               EL
       IM                  IM
            IN               IN
              AR               AR
                Y                Y
            Hubble diagram
•   overplot on nearby Hubble diagram (Guy 07)




                           Y
                         AR
                      IN
                  IM
                EL
             PR
            Hubble diagram
•   correction for α, β (from the cosmological fit)
    does not fully account for all the residuals
             Hubble diagram




                                          Y
                                        AR
                                     IN
 •   correction for α, β (from the cosmological fit)




                                  IM
     does not fully account for all the residuals




                              EL
                           PR
             Y
           AR
        IN
   IM
 EL
PR
    Conclusion & perspectives

•   SNfactory entered production phase

    •   calibration under way

•   hundreds of high-quality spectra for a large
    dataset of nearby SNe Ia

    •   probing SNe spectroscopic and
        photometric diversity

•   cosmological analysis during 2008

				
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posted:7/13/2011
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