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Abstract We present cosmological-scale three-dimensional neutral hydrogen (Hi) tomographic maps atz= 2–3 over a total of 837 deg2in two blank fields that are developed with Lyαforest absorptions of 14,736 background Sloan Digital Sky Survey (SDSS) quasars atz= 2.08–3.67. Using the tomographic maps, we investigate the large-scale (≳10h−1cMpc) average Hiradial profiles and two-direction profiles of the line-of-sight (LOS) and transverse directions around galaxies and active galactic nuclei (AGNs) atz= 2–3 identified by the Hobby–Eberly Telescope Dark Energy eXperiment survey and SDSS, respectively. The peak of the Hiradial profile around galaxies is lower than the one around AGNs, suggesting that the dark matter halos of galaxies are less massive on average than those of AGNs. The LOS profile of AGNs is narrower than the transverse profile, indicating the Kaiser effect. There exist weak absorption outskirts at ≳30h−1cMpc beyond Histructures of galaxies and AGNs found in the LOS profiles that can be explained by the Higas at ≳30h−1cMpc falling toward the source position. Our findings indicate that the Hiradial profile of AGNs has transitions from proximity zones (≲a fewh−1cMpc) to the Histructures (∼1–30h−1cMpc) and the weak absorption outskirts (≳30h−1cMpc). Although there is no significant dependence of AGN types (type 1 vs. type 2) on the Hiprofiles, the peaks of the radial profiles anticorrelate with AGN luminosities, suggesting that AGNs’ ionization effects are stronger than the gas mass differences.
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This content will become publicly available on March 2, 2027
New Insight from the James Webb Space Telescope on Variable Active Galactic Nuclei
Abstract Variability detected in galaxies is usually attributed to their active galactic nuclei (AGNs). While all AGNs are intrinsically variable, the AGN unification model predicts that Type 2 AGNs rarely vary because their engines are blocked by dust tori. Previous UV to near-IR variability studies largely support this expectation. Here, we present a variability study with the James Webb Space Telescope (JWST) that reveals a more subtle picture. Using NIRCam imaging data from three surveys over ∼140 arcmin2in the COSMOS field, we found 117 galaxies with ≥4σvariability in the F356W band across an ∼2 yr baseline. Crossmatching with existing JWST spectroscopic data, we identified five of them atz= 0.19–3.69 (F356W corresponding to rest-frameλ ≈ 0.76–2.97 μm), which were all coincidentally observed by an NIRSpec program almost contemporaneously with the last imaging epoch. One additional variable was identified atz= 0.90 using archival Keck telescope data. These six objects form our spectroscopic subsample. Interestingly, two reside in close-pair environments, while two others form a close pair themselves. Most of their light curves can hardly be explained by nuclear transients, and AGN variability is a more plausible cause. However, among these six objects (1) only one shows broad Bracket and Pfund series permitted lines (Δv > 1000 km s−1) indicative of a Type 1 AGN; (2) two show narrow permitted lines (Hαand/or He Iλ10830) consistent with Type 2 AGNs, with another one likely Type 2 based on the host galaxy properties; and (3) two others, which form a pair, show no emission lines. Our results add more challenges to the unification model.
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- Award ID(s):
- 2307447
- PAR ID:
- 10704038
- Publisher / Repository:
- IOP Science
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 999
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 152
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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