Spectroscopic standardisation of the ZTF-SEDm Type Ia supernova sample (Constance Ganot, IP2I)

par CONSTANCE GANOT, Constance Ganot

lundi 1 déc. 2025, 14:00 → 16:00 Europe/Paris

amphi Charpak

Type Ia Supernovae (SNe Ia) are standardisable cosmological candles used to measure cosmic distances from their nearly constant maximum luminosity. Standardisation methods have been developed to reduce intrinsic scatter and improve distance estimates. Traditional photometric method reaches a ~0.15 mag precision, but the SNFactory (SNf) survey has suggested that a spectroscopic approach can reach ~0.07 mag. We applied for the first time this spectroscopic method, called the Twins Embedding (TE), using an other survey. The Zwicky Transient Facility (ZTF) SNe Ia spectral sample contains about 700 spectroscopic SNe Ia. It is an homogeneous dataset from the SEDm spectrograph, four times larger than SNf for the same selection cuts.

During the presentation, I will talk about the general context on which this study is set, and explain why this new approach would improve future cosmological results. I will present results of applying TE to the ZTF sample, and I will discuss the robustness of the method and its limits, in light of the new spectroscopic surveys of SN.

seminaire_lpnhe.pdf