TYPE Ia SUPERNOVA RATE MEASUREMENTS TO REDSHIFT 2.5 FROM CANDELS: SEARCHING FOR PROMPT EXPLOSIONS IN THE EARLY UNIVERSE

Abstract

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ∼0.25 deg 2 with ∼900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z ∼ 2.5. We classify ∼24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ∼3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f P = 0.53 ±0.09 stat0.10 ±0.10 sys0.26 , consistent with a delay time distribution that follows a simple t −1 power law for all times t > 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions-though further analysis and larger samples will be needed to examine that suggestion.

Measuring the Properties of Dark Energy with Photometrically Classified Pan-STARRS Supernovae. I. Systematic Uncertainty from Core-collapse Supernova Contamination

“…There are likely substantial differences between the reddening distribution of the templates and the data. However, we find that adding additional reddening to our simulations tends to make the magnitude distribution of CC SNe broader (we approximately adjust the Li et al 2011 LFs for dust following Rodney et al 2014). This increases the discrepancy between simulations and data.…”

“…SNANA creates a combined SN Ia+CC simulation, with each SN type normalized by its rate. The redshift-dependent SN rates used in this work are the same as the baseline model of Rodney et al (2014). SNe Ia follow measured rates, while CC SNe follow the cosmic star formation history.…”

“…Because many SNe Ia have a 1 Gyr delay time between progenitor formation and explosion (Rodney et al 2014), they are the only type of SNe found in early-type galaxies (with very few known exceptions; Suh et al 2011). Foley & Mandel (2013) found that it was possible to accurately classify the ∼20% of SNe Ia found in elliptical galaxies if the morphology of their host galaxy is known.…”

LATE-TIME PHOTOMETRY OF TYPE IA SUPERNOVA SN 2012cg REVEALS THE RADIOACTIVE DECAY OF 57Co

“…We performed aperture photometry of SN 2012cg in a 0 4-diameter aperture using the hstsnphot 7 program used by the CLASH and CANDELS SN surveys (Graur et al 2014b;Rodney et al 2014), which is based on the IRAF 8 apphot routine (Tody 1986). Due to the faintness of the SN on the last observation epoch, 2015 April 26.6, we used a smaller aperture with a diameter of 0 24, along with a larger aperture correction, to capture the low flux counts.…”

LOSS Revisited. I. Unraveling Correlations between Supernova Rates and Galaxy Properties, as Measured in a Reanalysis of the Lick Observatory Supernova Search

“…We confirmed this trend for SNe Ia in starforming galaxies in Graur & Maoz (2013) and for SNe II in Graur et al (2015, hereafter G15). Following Kistler et al (2013), we argued that the dependence of the SN Ia rates on stellar mass results from a combination of galaxy scaling relations (older galaxies are more massive, on average, than younger ones; Gallazzi et al 2005) and the SN Ia delay-time distribution (DTD), which behaves as a power law with an index of ∼ −1 (e.g., observations by Totani et al 2008;Maoz & Badenes 2010;Graur et al 2011Graur et al , 2014bRodney et al 2014; and reviews by Wang & Han 2012;Hillebrandt et al 2013;Maoz et al 2014). Mannucci et al (2005), Sullivan et al (2006), Smith et al (2012), and G15 also measured SN Ia rates as a function of the galaxies' specific star-formation rate (sSFR).…”