Annual Review of Astronomy and Astrophysics· 2015Q1· Review
Revisiting the Unified Model of Active Galactic Nuclei
- 849citations
- Q1SCImago
- 2015year
Short summary
Recent advancements in understanding Active Galactic Nuclei (AGNs) focus on the central obscuring torus and its environment, with new models involving disk winds and hydrodynamic simulations.
AI-generated from the title and abstract; the full text is not read.
Key points
- New models for AGNs involve disk winds and hydrodynamic simulations connecting galactic disks to accretion flows.
- Infrared studies have advanced understanding of AGN spectral energy distribution, though selection effects remain a challenge.
- X-ray samples offer a more complete view of AGNs compared to infrared studies.
- The covering factor of the torus's dependence on luminosity is a key unexplained relationship.
- IR interferometry and ionization cone mapping provide impressive new data, sometimes conflicting with existing torus models.
AI-generated from the title and abstract; the full text is not read.
Abstract
This review describes recent developments related to the unified model of active galactic nuclei (AGNs). It focuses on new ideas about the origin and properties of the central obscurer (torus) and the connection to its surroundings. The review does not address radio unification. AGN tori must be clumpy but uncertainties about their properties persist. Today's most promising models involve disk winds of various types and hydrodynamic simulations that link the large-scale galactic disk to the inner accretion flow. Infrared (IR) studies greatly improved our understanding of the spectral energy distribution of AGNs, but they are hindered by various selection effects. X-ray samples are more complete. The dependence of the covering factor of the torus on luminosity is a basic relationship that remains unexplained. There is also much confusion regarding real type-II AGNs, which do not fit into a simple unification scheme. The most impressive recent results are due to IR interferometry, which is not in accord with most torus models, and the accurate mapping of central ionization cones. AGN unification may not apply to merging systems and is possibly restricted to secularly evolving galaxies.
The authors' abstract, as published at the source. Annual Review of Astronomy and Astrophysics, 2015 · DOI ↗
Continue with a free account
Ask the paper: 3 free questions a day about this paper; save it, get its citation, new summaries every day for your field. Takeaways are Premium.
Continue free on the webSign in with Google or Apple; no card needed. You come back to this paper.
On your phone:
Field: Instrumentation
InstrumentationPhysics and Astronomy