A Type Ia Supernova at Redshift 1.55 in Hubble Space Telescope Infrared Observations from CANDELS
Ferguson, Henry C.; Grogin, Norman A.; Weiner, Benjamin J.; Casertano, Stefano; Filippenko, Alexei V.; Scarlata, Claudia; Jones, David O.; Mobasher, Bahram; Garnavich, Peter; Riess, Adam G.; Kirshner, Robert P.; Faber, S. M.; Hjorth, Jens; Koekemoer, Anton; Graur, Or; Challis, Peter; Strolger, Louis-Gregory; Dahlen, Tomas; Kocevski, Dale; Rajan, Abhijith; Hayden, Brian; Jha, Saurabh W.; McCully, Curtis; Rodney, Steven A.; Patel, Brandon; Frederiksen, Teddy F.
United States, Denmark, Israel
Abstract
We report the discovery of a Type Ia supernova (SN Ia) at redshift z = 1.55 with the infrared detector of the Wide Field Camera 3 (WFC3-IR) on the Hubble Space Telescope (HST). This object was discovered in CANDELS imaging data of the Hubble Ultra Deep Field and followed as part of the CANDELS+CLASH Supernova project, comprising the SN search components from those two HST multi-cycle treasury programs. This is the highest redshift SN Ia with direct spectroscopic evidence for classification. It is also the first SN Ia at z > 1 found and followed in the infrared, providing a full light curve in rest-frame optical bands. The classification and redshift are securely defined from a combination of multi-band and multi-epoch photometry of the SN, ground-based spectroscopy of the host galaxy, and WFC3-IR grism spectroscopy of both the SN and host. This object is the first of a projected sample at z > 1.5 that will be discovered by the CANDELS and CLASH programs. The full CANDELS+CLASH SN Ia sample will enable unique tests for evolutionary effects that could arise due to differences in SN Ia progenitor systems as a function of redshift. This high-z sample will also allow measurement of the SN Ia rate out to z ≈ 2, providing a complementary constraint on SN Ia progenitor models.