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EnglishWe present AGN feedback in the interesting cases of two groups: AWM 4 and NGC 5044. AWM 4 is characterized by a combination of properties which seems to defy the paradigm for AGN heating in cluster cores: a flat inner temperature profile indicative of a past, major heating episode which completely erased the cool core, as testified by the high central cooling time (> 3 Gyrs) and by the high central entropy level (∼50 keV cm2), and yet an active central radio galaxy with extended radio lobes out to 100 kpc, revealing recent feeding of the central massive black hole. A recent Chandra observation has revealed the presence of a compact cool corona associated with the BCG, solving the puzzle of the apparent lack of low entropy gas surrounding a bright radio source, but opening the question of its origin. NGC 5044 shows in the inner 10 kpc a pair of cavities together with a set of bright filaments. The cavities are consistent with a recent AGN outburst as also indicated by the extent of dust and Hα emission even though the absence of extended 1.4 GHz emission remains to be explained. The soft X-ray filaments coincident with Hα and dust emission are cooler than those which do not correlate with optical and infrared emission, suggesting that dust-aided cooling can contribute to the overall cooling. For the first time sloshing cold fronts at the scale of a galaxy group have been observed in this object. © 2009 American Institute of Physics.
| Titolo: | AGN feedback in galaxy groups: The two interesting cases of AWM 4 and NGC 5044 |
| Autore/i: | GASTALDELLO, FABIO; Buote, David A.; BRIGHENTI, FABRIZIO; Mathews, William G.; Temi, Pasquale; Ettori, Stefano |
| Autore/i Unibo: | |
| Anno: | 2009 |
| Rivista: | |
| Titolo del libro: | AIP Conference Proceedings |
| Pagina iniziale: | 237 |
| Pagina finale: | 240 |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1063/1.3293045 |
| Abstract: | We present AGN feedback in the interesting cases of two groups: AWM 4 and NGC 5044. AWM 4 is characterized by a combination of properties which seems to defy the paradigm for AGN heating in cluster cores: a flat inner temperature profile indicative of a past, major heating episode which completely erased the cool core, as testified by the high central cooling time (> 3 Gyrs) and by the high central entropy level (∼50 keV cm2), and yet an active central radio galaxy with extended radio lobes out to 100 kpc, revealing recent feeding of the central massive black hole. A recent Chandra observation has revealed the presence of a compact cool corona associated with the BCG, solving the puzzle of the apparent lack of low entropy gas surrounding a bright radio source, but opening the question of its origin. NGC 5044 shows in the inner 10 kpc a pair of cavities together with a set of bright filaments. The cavities are consistent with a recent AGN outburst as also indicated by the extent of dust and Hα emission even though the absence of extended 1.4 GHz emission remains to be explained. The soft X-ray filaments coincident with Hα and dust emission are cooler than those which do not correlate with optical and infrared emission, suggesting that dust-aided cooling can contribute to the overall cooling. For the first time sloshing cold fronts at the scale of a galaxy group have been observed in this object. © 2009 American Institute of Physics. |
| Data stato definitivo: | 27-nov-2016 |
| Appare nelle tipologie: | 4.01 Contributo in Atti di convegno |
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http://hdl.handle.net/11585/570910
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