2DARK天文志

Abstract: We present
distance measurements to 71 high redshift type Ia supernovae discovered during
the first year of the 5-year Supernova Legacy Survey (SNLS). These events were
detected and their multi-color light-curves measured using the MegaPrime/MegaCam
instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging
four one-square degree fields in four bands. Follow-up spectroscopy was
performed at the VLT, Gemini and Keck telescopes to confirm the nature of the
supernovae and to measure their redshift. With this data set, we have built a
Hubble diagram extending to z=1, with all distance measurements involving at
least two bands. Systematic uncertainties are evaluated making use of the
multi-band photometry obtained at CFHT. Cosmological fits to this first year
SNLS Hubble diagram give the following results : Omega_M = 0.263 +/- 0.042(stat)
+/- 0.032(sys) for a flat LambdaCDM model; and w = -1.023 +/- 0.090(stat) +/-
0.054(sys) for a flat cosmology with constant equation of state w when combined
with the constraint from the recent Sloan Digital Sky Survey measurement of
baryon acoustic oscillations.