Precision Measurement of The Most Distant Spectroscopically Confirmed Supernova Ia with the Hubble Space Telescope

TL;DR

This paper reports the discovery and spectroscopic confirmation of the most distant Type Ia supernova at redshift 1.71, providing valuable data for cosmology and dark energy studies.

Contribution

It presents the first spectroscopic confirmation of a supernova Ia at such a high redshift with precise measurements, utilizing HST data and principal component analysis.

Findings

Most distant spectroscopically confirmed SN Ia at z=1.71

Supernova distance aligns with LambdaCDM predictions

Achieved high-confidence classification with minimal host contamination

Abstract

We report the discovery of a redshift 1.71 supernova in the GOODS North field. The Hubble Space Telescope (HST) ACS spectrum has almost negligible contamination from the host or neighboring galaxies. Although the rest frame sampled range is too blue to include any Si ii line, a principal component analysis allows us to confirm it as a Type Ia supernova with 92% confidence. A recent serendipitous archival HST WFC3 grism spectrum contributed a key element of the confirmation by giving a host-galaxy redshift of 1.713 +/- 0.007. In addition to being the most distant SN Ia with spectroscopic confirmation, this is the most distant Ia with a precision color measurement. We present the ACS WFC and NICMOS 2 photometry and ACS and WFC3 spectroscopy. Our derived supernova distance is in agreement with the prediction of LambdaCDM.