A Catalog of Near Infrared Spectra from Type Ia Supernovae

TL;DR

This paper presents a comprehensive set of near-infrared spectra from 41 Type Ia supernovae, analyzing spectral features, velocities, and chemical distributions to enhance understanding of explosion mechanisms and improve their use as cosmological tools.

Contribution

It provides the first extensive NIR spectral dataset for SNe Ia, detailing procedures for analysis and revealing insights into explosion product distribution and chemical composition.

Findings

Spectral features develop consistently over time in NIR spectra.

Burning products are layered with minimal mixing, and no significant carbon detected.

Outer layers contain oxygen and magnesium, indicating complete progenitor burning.

Abstract

We present forty-one near infrared (NIR, 0.7-2.5 microns) spectra from normal Type Ia supernovae (SNe Ia) obtained at epochs ranging from fourteen days before to seventy-five days with respect to the maximum light date in the V-band. All data were obtained at the IRTF using the SpeX instrument. We identify many spectral features, measure the Doppler velocities, and discuss the chemical distribution of explosion products in SNe Ia. We describe procedures for smoothing data, fitting continua, and measuring absorption features to insure consistency for measurement and analysis. This sample provides the first opportunity to examine and compare a large number of SNe Ia in this wavelength region. NIR data are a rich source of information about explosion products whose signatures are blended or obscured in other spectral regions and NIR observations probe a greater radial depth than optical wavelengths. We analyze similarities and differences in the spectra and we show that the progressive development of spectral features for normal SNe Ia in the NIR is consistent with time. Measured Doppler velocities indicate that burning products in SNe Ia are distributed in distinct layers with no large scale mixing. Carbon is not detected in these data, in agreement with previous results with NIR data establishing very low limits on carbon abundance in SNe Ia. Carbon burning products, O and Mg, are plentiful in the outer layers suggesting that the entire progenitor is burned in the explosion. The data provide a resource for investigations of cross-correlations with other data libraries that may further constrain SN Ia physics and improve the effectiveness of SNe Ia as cosmological distance indicators.