Probing the He <scp>ii</scp> re-Ionization ERa via Absorbing C <scp>iv</scp> Historical Yield (HIERACHY). II. Project Design, Current Status, and Examples of Initial Data Products
Abstract The He ii reionization epoch is expected to take place at z ∼ 3–5. In this stage, the helium and metals in the intergalactic medium are further ionized with additional contributions from harder nonstellar sources, and some large-scale gravitationally bound systems approach virialization. The Probing the He ii re-Ionization ERa via Absorbing C iv Historical Yield (HIERACHY) program utilizes high- and medium-resolution spectra of bright background quasars at z ≈ 3.9–5.2 to investigate Ly α , C iv , and other metal absorption lines during this epoch. Additionally, we employ narrowband imaging to search for Ly α emitters associated with C iv absorbers, alongside multiwavelength observations to identify and study particularly intriguing cases. In this paper, we present the design of the HIERACHY program, its current status, major scientific goals, and examples of initial data products from completed Magellan/MIKE, MagE spectroscopy, and MDM imaging observations. We also provide a brief outlook on future multiwavelength observations that may significantly impact the related science.
Authors
- Ji Li (ORCID: https://orcid.org/0000-0002-6632-3422)
- Fuyan Bian (ORCID: https://orcid.org/0000-0002-1620-0897)
- Zhijie Qu (ORCID: https://orcid.org/0000-0002-2941-646X)
- Zhiyuan Ji (ORCID: https://orcid.org/0000-0001-7673-2257)
- Sean D. Johnson (ORCID: https://orcid.org/0000-0001-9487-8583)
- Xiaohui Fan (ORCID: https://orcid.org/0000-0003-3310-0131)
- Jinyi Yang (ORCID: https://orcid.org/0000-0001-5287-4242)
- Yang Yang (ORCID: https://orcid.org/0000-0001-7254-219X)
- Tiancheng Yang (ORCID: https://orcid.org/0000-0002-7967-9727)
- Feige Wang (ORCID: https://orcid.org/0000-0002-7633-431X)
- Taotao Fang (ORCID: https://orcid.org/0000-0002-2853-3808)
- Weizhe Liu (ORCID: https://orcid.org/0000-0003-3762-7344)
- Xin Wang (ORCID: https://orcid.org/0000-0002-9373-3865)
- Joel N. Bregman (ORCID: https://orcid.org/0000-0001-6276-9526)
- Ying-Yi Song (ORCID: https://orcid.org/0000-0002-6270-8851)
- Mingxuan Xu
- Xiaodi Yu (ORCID: https://orcid.org/0009-0004-1889-3043)
- Jiangtao Li (ORCID: https://orcid.org/0000-0001-6239-3821)
- Guoliang Li (ORCID: https://orcid.org/0000-0002-1751-242X)
- Tao Wang (ORCID: https://orcid.org/0000-0001-7852-0901)
- Hanxiao Chen (ORCID: https://orcid.org/0000-0001-8892-8759)
- Zheng Cai (ORCID: https://orcid.org/0009-0007-8000-3912)
- Huiyang Mao (ORCID: https://orcid.org/0009-0006-7138-2095)
- Christina Williams
- Xianzhong Zheng
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-05-15
- DOI
- https://doi.org/10.3847/1538-4357/adc89d
- Citations
- 2
- Primary Topic
- Gamma-ray bursts and supernovae
- Type
- article
- Field-Weighted Citation Impact
- 2.31
Funders
- National Natural Science Foundation of China