The multiphase environment in the centre of Centaurus A
Bibliographic record
Abstract
ABSTRACT We study the multiphase medium in the vicinity of the active galactic nucleus Centaurus A (Cen A). Combined high-resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and Chandra X-ray Observatory indicate that the hot X-ray emitting plasma coexists with the warm and cold media in Cen A. This complex environment is a source of CO lines with great impact for its diagnostics. We present the images from the two above-mentioned instruments covering the nuclear region (diameter of 10 arcsec, i.e. ∼180 pc), and we study the conditions for plasma thermal equilibrium and possible coexistence of cool clouds embedded within the hot X-ray emitting gas. Further, we demonstrate that the multiphase medium originates naturally by the thermal instability arising due to the interaction of the high-energy radiation field from the nucleus with the ambient gas and dust. We demonstrate that cold gas clouds can coexist in the mutual contact with hot plasma, but even colder dusty molecular clouds have to be distanced by several hundred pc from the hot region. Finally, we propose a 3D model of the appearance of the hot plasma and the CO line-emitting regions consistent with the Chandra image, and we derive the integrated emissivity in specific molecular lines observed by ALMA from this model. To reproduce the observed images and the CO line luminosity the dusty shell has to be ∼420 pc thick and located at ∼1000 pc from the centre.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".