THE RATE OF TYPE Ia SUPERNOVAE AT HIGH REDSHIFT

摘要

We derive the rates of Type Ia supernovae (SNe Ia) over a wide range of redshifts using a complete sample from the IfA Deep Survey. This sample of more than 100 SNe Ia is the largest set ever collected from a single survey and therefore uniquely powerful for a detailed supernova rate (SNR) calculation. Measurements of the SNR as a function of cosmological time offer a glimpse into the relationship between the star formation rate (SFR) and Type Ia SNR and may provide evidence for the progenitor pathway. We observe a progressively increasing Type Ia SNR between redshifts z ≈ 0.3 and 0.8. The Type Ia SNR measurements are consistent with a short time delay (t ≈ 1 Gyr) with respect to the SFR, indicating a fairly prompt evolution of SN Ia progenitor systems. We derive a best-fit value of SFR/SNR ≈ 580 h_(70)~(-2) solar mass per SN Ia for the conversion factor between the star formation and the SN Ia rates, as determined for a delay time of t ≈ 1 Gyr between the SFR and the Type Ia SNR. More complete measurements of the Type Ia SNR at z > 1 are necessary to conclusively determine the SFR-SNR relationship and constrain SN Ia evolutionary pathways.