The Zwicky Transient Facility Type Ia supernova survey: first data release and results

Abstract

Type Ia supernovae (SNe Ia) in the nearby Hubble flow are excellent distance indicators in cosmology. The Zwicky Transient Facility (ZTF) has observed a large sample of supernovae from an untargeted, rolling survey, reaching 20.8, 20.6, 20.3 mag in g r, and i-band, respectively. With a FoV of 47 sq.deg, ZTF discovered > 3000 SNe Ia in a little over 2.5 years. Here, we report on the sample of 761 spectroscopically classified SNe Ia from the first year of operations (DR1). The sample has a median redshift $\bar{z} =$ 0.057, nearly a factor of two higher than the current low-z sample. Our sample has a total of 934 spectra, of which 632 were obtained with the robotic SEDm on Palomar P60. We assess the potential for precision cosmology for a total of 305 SNe with redshifts from host galaxy spectra. The sample is already comparable in size to the entire combined literature low-z anchor sample. The median first detection is 13.5 days before maximum light, about 10 days earlier than the median in the literature. Furthermore, six SNe from our sample are at DL < 80 Mpc, for which host galaxy distances can be obtained in the JWST era, such that we have calibrator and Hubble flow SNe observed with the same instrument. In the entire duration of ZTF-I, we have observed nearly fifty SNe for which we can obtain calibrator distances, key for percent level distance scale measurements.

The Pantheon+ Analysis: The Full Dataset and Light-Curve Release

“…The size of a sample like this will soon be surpassed by other samples from newer and upcoming surveys like the Zwicky Transient Facility (ZTF; Dhawan et al 2021), the Young Supernova Experiment (YSE; Jones et al 2021), the Dark Energy Survey (DES; Smith et al 2020), the Legacy Survey of Space and Time (LSST; Ivezić et al 2019), and the Nancy Grace Roman Space Telescope (Roman; Hounsell et al 2018). These surveys may find a similar number of SNe to this compilation in only a matter of days.…”

“…Since then, the continually growing sample size of these special "standardizable candles" has strengthened a key pillar of our understanding of the standard model of cosmology in which the universe is dominated by dark energy and dark matter. While modern transient surveys are now discovering as many SNe Ia in 5 yr as had been discovered in the last 40 yr (e.g., Smith et al 2020;Dhawan et al 2021;Jones et al 2021), progress in using these data for constraining cosmological parameters has been made by the compilation of multiple samples (e.g., Betoule et al 2014;Scolnic et al 2018;Brout et al 2019a;Jones et al 2019). The reason for this is that different surveys are optimized to discover and measure SNe in different redshift ranges, and the constraints on cosmological parameters benefit from leveraging measurements at different redshifts.…”

A Uniform Type Ia Supernova Distance Ladder with the Zwicky Transient Facility: Absolute Calibration Based on the Tip of the Red Giant Branch (TRGB) Method

“…We combine the calibrator data with the ZTF DR1 Hubble flow sample (Dhawan et al 2022). TRGB stars are found in all types of SN Ia host galaxies and therefore, the TRGB-calibrated sample will be volume limited.…”

Observational constraints on the deceleration parameter in a tilted universe

“…We expect that the ongoing [103,107] and the forthcoming [108] wide-field surveys should achieve exquisite precision in their bulk-flow measurements and in so doing provide us with accurate kinematic estimates of the observed peculiar velocity fields.…”

“…(2.13), as well as the use of different types of cosmological data. Those from the Pantheon+ dataset [15], the SnIa compilation on [103], or from SnIa and from Sn of type II [104], should help to constrain further the parameters of the tilted model.…”