Assaf Horesh Supernovae Page

The Rate of Type Ia Supernovae at z~0.2 from SDSS-I Overlapping Fields

Authors: Assaf Horesh, Dovi  Poznanski, Eran O. Ofek, Dan Maoz

In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of the surveyed area was observed more than once due to field tiling overlap, usually at different epochs. We utilize some of these data to perform a supernova (SN) survey at a mean redshift of z=0.2. Our archival search, in ~ 5% of the SDSS-I overlap area, produces 29 SN candidates clearly associated with host galaxies. Using the Bayesian photometric classification algorithm of Poznanski et al., and correcting for classification bias, we find 17 of the 29 candidates are likely Type Ia SNe. Accounting for the detection efficiency of the survey and for host extinction, this implies a Type Ia SN rate of R=14.0+(2.5,1.4}-(2.5,1.1}+/-2.5 10^-14 h(70)^2 yr^-1 L_sun^-1, where the errors are Poisson error, systematic detection efficiency error, and systematic classification error, respectively. The volumetric rate is R=1.89+(0.42,0.18)-(0.34,0.15)+/-0.42 10^-5 yr^-1 h(70)^3 Mpc^-3. Our measurement is consistent with other rate measurements at low redshift. An order of magnitude increase in the number of SNe is possible by analyzing the full SDSS-I database.

A subsample of our SN candidates. The left and center panels are two different epochs and the right panel is their subtraction image in which you can see the SN candidate.

A compilation of different Type Ia SN rate measurements, including ours (marked as "this work").

Contact Information:
Address: Department of Astronomy and Astrophysics, Tel Aviv University, 69978 Tel Aviv, Israel
E-Mail: assafh@wise.tau.ac.il
Phone: +972-3-6405121
Fax: +972-3-6408179