The Carnegie Supernova Project: Light Curve Fitting with SNooPy

TL;DR

This paper introduces new light-curve templates and distance measurement methods for Type Ia supernovae using near-infrared observations, improving cosmological distance estimates.

Contribution

It develops new NIR light-curve templates and two distance determination methods calibrated with low-z supernovae, enhancing accuracy in cosmic expansion studies.

Findings

Created uBVgriYJH light-curve templates from 24 low-z SNe.

Calibrated two distance measurement methods with 30 low-z SNe.

Derived distances to seven nearby galaxies.

Abstract

In providing an independent measure of the expansion history of the Universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble Flow are used to calibrate these methods. We then apply the method and derive distances to seven galaxies that are so nearby that their motions are not dominated by the Hubble flow.