# First observation of double-peaked O I emission in the near-infrared spectrum of an active galaxy

**Authors:** Denimara Dias dos Santos, Alberto Rodríguez-Ardila, Swayamtrupta Panda, Murilo Marinello  
**arXiv:** [2308.04555](https://arxiv.org/abs/2308.04555)  
**Date:** 2023-08-08  
**Summary page:** https://www.summarizepaper.com/en/paper/2308.04555v1/

## Key points

- Double-peaked profiles in the broad-line region (BLR) of active galactic nuclei (AGNs) indicate the presence of an accretion disk
- Previously, double-peaked profiles were observed in optical spectroscopy, but now they have been detected in the near-infrared (NIR) spectrum
- The O I λ11297 emission line in a local Seyfert 1 galaxy called III Zw 002 shows a double-peak broad emission line in the NIR spectrum
- Double-peak emissions were also observed in the Paα and potentially He II λ10830 lines within the same spectrum
- A disk-based model was used to analyze these observations and determine important parameters such as disk inclination and geometry
- The results suggest that the BLR in III Zw 002 has a disk-like geometry extending to its outer edge
- This finding provides valuable insights into AGNs and their accretion processes
- Detection of multiple broad double-peaked NIR emission lines opens up new avenues for further research and exploration

## Summary

In a recent study, researchers have made an exciting discovery in the field of active galactic nuclei (AGNs). Double-peaked profiles associated with the broad-line region (BLR) of AGNs are considered strong evidence for the presence of an accretion disk. These profiles are typically observed through optical spectroscopy in Balmer lines and the Mg II λ2798 ultraviolet line. However, for the first time, scientists have detected a double-peak broad emission line associated with the O I λ11297 emission line in the near-infrared (NIR) spectrum of a local Seyfert 1 galaxy called III Zw 002. In addition to this groundbreaking finding, the researchers also simultaneously detected double-peak emissions in the Paα line and potentially in the He II λ10830 line within the same spectrum. This marks a significant milestone as it is the first instance where multiple broad double-peaked NIR emission lines have been observed together. To analyze these observations, a disk-based model was employed to fit the double-peaked profiles. The model also included an additional Gaussian component attributed to nondisk clouds, representing the classical BLR. Through this fitting process, important parameters such as disk inclination and geometry were determined. The results obtained from these fits suggest that the BLR in III Zw 002 exhibits a disk-like geometry that extends up to its outer edge. This finding provides valuable insights into understanding AGNs and their accretion processes. Overall, this study presents compelling evidence for double-peaked NIR emission lines associated with AGNs and highlights their significance in studying accretion disks and BLRs. The detection of multiple broad double-peaked NIR emission lines opens up new avenues for further research and exploration in this field.