COSMOS-3D: Two obscured X-ray AGNs with hot dust and He I$lambda$10830 absorption at z~3

COSMOS-3D: Two obscured X-ray AGNs with hot dust and He I$lambda$10830 absorption at z~3
Zi-Jian Li, Siwei Zou, Jianwei Lyu, Jaclyn B. Champagne, Jia-Sheng Huang, Cheng Cheng, Shuqi Fu, Zijian Zhang, Danyang Jiang, Khee-Gan Lee, Feige Wang, Xiaohui Fan, Jinyi Yang, Ruancun Li, Hollis B. Akins, Fuyan Bian, Y. Sophia Dai, Andreas L. Faisst, Luis C. Ho, Kohei Inayoshi, Linhua Jiang, Xiangyu Jin, Koki Kakiichi, Jeyhan S. Kartaltepe, Zihao Li, Weizhe Liu, Jan-Torge Schindler, Wei Leong Tee
arXiv:2512.02093v2 Announce Type: replace
Abstract: We report the discovery of two broad-line X-ray AGNs cid_414 and cid_947 at z~3 that exhibit prominent He I$lambda$10830+ Pa$gamma$ emission and absorption, identified from the JWST Cycle 3 large GO treasury program COSMOS-3D using NIRCam F444W grism spectroscopy. Additional UV/optical line measurements (e.g., Ly$alpha$, Si IV, C IV) come from complementary COSMOS-field spectroscopy. Both sources are robustly detected in the mid-infrared, with detections in MIRI F1000W for both AGNs and an additional detection in MIRI F2100W for cid_414, indicating the presence of hot dust emission. The source cid_947 shows a higher He I$lambda$10830 absorption column density and X-ray-inferred $N_{rm H}$, and displays strong outflow signatures in He I, Si IV, and C IV with velocity offsets exceeding 5000 km/s. The source cid_414 shows a narrow Ly$alpha$ emission line with luminosity $log L_{rm Lyalpha}=42.49pm0.01~mathrm{erg~s^{-1}}$ and a higher intrinsic 2-10 keV X-ray luminosity. Host-galaxy decomposition and multi-component SED fitting indicate that cid_947 hosts a more massive black hole but lower star formation rate than cid_414. From simplified photoionization modeling, we infer that the dense absorbing gas has a characteristic size comparable to the nuclear broad-line region and is likely kinematically coupled to the obscuration associated with the dust torus. He I$lambda$1083 absorption has also been identified in several compact little red dots at similar redshifts. Together with the two AGNs reported here, these findings suggest that dense circumnuclear gas are plausibly prevalent at high redshift and plays an important role in regulating AGN obscuration and black hole–host co-evolution.arXiv:2512.02093v2 Announce Type: replace
Abstract: We report the discovery of two broad-line X-ray AGNs cid_414 and cid_947 at z~3 that exhibit prominent He I$lambda$10830+ Pa$gamma$ emission and absorption, identified from the JWST Cycle 3 large GO treasury program COSMOS-3D using NIRCam F444W grism spectroscopy. Additional UV/optical line measurements (e.g., Ly$alpha$, Si IV, C IV) come from complementary COSMOS-field spectroscopy. Both sources are robustly detected in the mid-infrared, with detections in MIRI F1000W for both AGNs and an additional detection in MIRI F2100W for cid_414, indicating the presence of hot dust emission. The source cid_947 shows a higher He I$lambda$10830 absorption column density and X-ray-inferred $N_{rm H}$, and displays strong outflow signatures in He I, Si IV, and C IV with velocity offsets exceeding 5000 km/s. The source cid_414 shows a narrow Ly$alpha$ emission line with luminosity $log L_{rm Lyalpha}=42.49pm0.01~mathrm{erg~s^{-1}}$ and a higher intrinsic 2-10 keV X-ray luminosity. Host-galaxy decomposition and multi-component SED fitting indicate that cid_947 hosts a more massive black hole but lower star formation rate than cid_414. From simplified photoionization modeling, we infer that the dense absorbing gas has a characteristic size comparable to the nuclear broad-line region and is likely kinematically coupled to the obscuration associated with the dust torus. He I$lambda$1083 absorption has also been identified in several compact little red dots at similar redshifts. Together with the two AGNs reported here, these findings suggest that dense circumnuclear gas are plausibly prevalent at high redshift and plays an important role in regulating AGN obscuration and black hole–host co-evolution.