The Type Ia Supernova Rate at z ~0.5 from the Supernova Legacy Survey

J.D. Neill , M. Sullivan , D. Balam , C.J. Pritchet , D.A. Howell , K. Perrett , P. Astier (1) , E. Aubourg (2) , S. Basa (3) , R.G. Carlberg , A. Conley , S. Fabbro , D. Fouchez (4) , J. Guy (1) , I. Hook , R. Pain (1) , N. Palanque-Delabrouille (5) , N. Regnault (1) , J. Rich (5) , Richard Taillet (1) , G. Aldering , P. Antilogus (1) , V. Arsenijevic , C. Balland (6) , S. Baumont (1) , J. Bronder , R.S. Ellis , M. Filiol , A. Goncalves , D. Hardin (1) , M. Kowalski , C. Lidman (7) , V. Lusset (5) , M. Mouchet (6) , A. Mourao , S. Perlmutter , P. Ripoche (4) , D. Schlegel , C. Tao (4)

1 LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
2 APC - Cosmologie
3 LAM - Laboratoire d'Astrophysique de Marseille
4 CPPM - Centre de Physique des Particules de Marseille
5 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
6 APC (UMR_7164) - AstroParticule et Cosmologie
7 LUTH (UMR_8102) - Laboratoire Univers et Théories

We present a measurement of the distant Type Ia supernova rate derived from the first two years of the Canada -- France -- Hawaii Telescope Supernova Legacy Survey. We observed four one-square degree fields with a typical temporal frequency of ~ 4 observer-frame days over time spans of from 158 to 211 days per season for each field, with breaks during full moon. We used 8-10 meter-class telescopes for spectroscopic followup to confirm our candidates and determine their redshifts. Our starting sample consists of 73 spectroscopically verified Type Ia supernovae in the redshift range 0.2 < z < 0.6. We derive a volumetric SN Ia rate of r_V(=0.47) = 0.42^{+0.13}_{-0.09} (systematic) +- 0.06 (statistical) X 10^-4 yr^-1 Mpc^3, assuming h = 0.7, Omega_m = 0.3 and a flat cosmology. Using recently published galaxy luminosity functions derived in our redshift range, we derive a SN Ia rate per unit luminosity of r_L(=0.47) = 0.154^{+0.048}_{-0.033} (systematic) ^{+0.039}_{-0.031} (statistical) SNu. Using our rate alone, we place an upper limit on the component of SN Ia production that tracks the cosmic star formation history of 1 SN Ia per 10^3 M_sun of stars formed. Our rate and other rates from surveys using spectroscopic sample confirmation display only a modest evolution out to z=0.55.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

J.D. Neill, M. Sullivan, D. Balam, C.J. Pritchet, D.A. Howell, et al.. The Type Ia Supernova Rate at z ~0.5 from the Supernova Legacy Survey. The Astronomical Journal, 2006, 132, pp.1126-1145. ⟨10.1086/505532⟩. ⟨hal-00082961⟩