Survey of near-infrared diffuse interstellar bands in $Y$ and $J$ bands. I. Newly identified bands

TL;DR

This study conducted a high-resolution survey of near-infrared diffuse interstellar bands in the 0.91-1.33 micrometer range, identifying 54 DIBs including 25 new ones, and analyzed their properties and possible molecular carriers.

Contribution

It provides the first comprehensive catalog of NIR DIBs in this wavelength range, including newly detected bands and their characteristics, expanding understanding of DIBs and their carriers.

Findings

54 DIBs detected, 25 newly identified

NIR DIBs are generally narrower than optical DIBs

DIB carrier column densities decrease with increasing wavelength

Abstract

We searched for diffuse interstellar bands (DIBs) in the 0.91$<\lambda<$1.33 $\mu$m region by analyzing the near-infrared (NIR) high-resolution ($R=20,000$ and 28,000) spectra of 31 reddened early-type stars ($0.04<E(B-V)<4.58$) and an unreddened reference star. The spectra were collected using the WINERED spectrograph, which was mounted on the 1.3 m Araki telescope at Koyama Astronomical Observatory, Japan, in 2012--2016, and on the 3.58 m New Technology Telescope at La Silla Observatory, Chile, in 2017--2018. We detected 54 DIBs -- 25 of which are newly detected by this study -- eight DIB candidates. Using this updated list, the DIB distributions over a wide wavelength range from optical to NIR are investigated. The FWHM values of the NIR DIBs are found to be narrower than those of the optical DIBs on average, which suggests that the DIBs at longer wavelengths tend to be caused by larger molecules. Assuming that the larger carriers are responsible for the DIBs at longer wavelengths and have the larger oscillator strengths, we found that the total column densities of the DIB carriers tend to decrease with increasing DIB wavelength. The candidate molecules and ions for the NIR DIBs are also discussed.