Carnegie Supernova Project-II: Extending the Near-Infrared Hubble Diagram for Type Ia Supernovae to $z\sim0.1$

TL;DR

The CSP-II project extended the near-infrared Hubble diagram for Type Ia supernovae up to redshift 0.1, improving distance measurements by combining optical and near-infrared data.

Contribution

This study provides detailed data and methodology for using optical and near-infrared observations to enhance the precision of Type Ia supernova distance measurements.

Findings

Achieved better than 5% distance precision using combined optical and near-infrared data.

Extended the near-infrared Hubble diagram to z~0.1 for Type Ia supernovae.

Provided comprehensive photometric data and observational strategies.

Abstract

The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year program to obtain optical and near-infrared observations of a "Cosmology" sample of $\sim100$ Type Ia supernovae located in the smooth Hubble flow ($0.03 \lesssim z \lesssim 0.10$). Light curves were also obtained of a "Physics" sample composed of 90 nearby Type Ia supernovae at $z \leq 0.04$ selected for near-infrared spectroscopic time-series observations. The primary emphasis of the CSP-II is to use the combination of optical and near-infrared photometry to achieve a distance precision of better than 5%. In this paper, details of the supernova sample, the observational strategy, and the characteristics of the photometric data are provided. In a companion paper, the near-infrared spectroscopy component of the project is presented.