The Rate of Type Ia Supernovae at High Redshift

Abstract

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 À2 70 M 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.

The Type Ia Supernova Rate atz ≈ 0.5 from the Supernova Legacy Survey

“…The largest disagreement between published rates in Figure 10 (and in the literature as far as we know) is that between the rates at z = 0.55 of Pain et al (2002) and Barris & Tonry (2006). We point out that Barris & Tonry (2006) is a re-analysis of the data from Tonry et al (2003), which reported a rate that agrees with Pain et al (2002).…”

“…We find that the single Gaussian model fit to the Dahlen et al (2004) data consistently over-predicts the rates near and below z = 0.5. In particular, the rate from Barris & Tonry (2006) at z = 0.25 is more than 1σ below this model.…”

“…We point out that Barris & Tonry (2006) is a re-analysis of the data from Tonry et al (2003), which reported a rate that agrees with Pain et al (2002). The rate from Barris & Tonry (2006) is a factor of 3.9 higher than the rate from Pain et al (2002). If we add the errors on these rates in quadrature, this amounts to a 3.8σ difference.…”

“…This trend, compared with the SFH curve, shows some curious properties. The large gradient just beyond z = 0.5 observed in Barris & Tonry (2006) has no analog in the SFH curve, and neither does the apparent down-turn beyond z = 1.2 observed by Dahlen et al (2004). Fits of the delay function to various subsets of these data have produced no consensus on τ , or the form of the delay.…”

“…With the advent of widefield imagers on moderately large telescopes, recent surveys have been able to target specific volumes of space and directly calculate the volumetric rate. Examples of volumetric SN Ia rate calculations at a variety of redshifts can be found in the following studies (plotted in Figure 1) : Cappellaro et al (1999); Hardin et al (2000); Pain et al (2002); Madgwick et al (2003); Tonry et al (2003); Blanc et al (2004); Dahlen et al (2004); Barris & Tonry (2006). We plot the rates from these surveys as a function of redshift in Figure 1, along with a recent SFH fit from Hopkins & Beacom (2006), renormalized by a factor of 10 3 .…”