The core of the relaxed cluster AWM 4 is characterized by a unique combination of properties which defy a popular scenario for AGN heating of cluster cores. A flat inner temperature profile is indicative of a past, major heating episode which completely erased the cool core, as testified by the high central cooling time (3 Gyr) and by the high central entropy level (∼60 keV cm2 ). Yet the presence of a 1.4 GHz active central radio galaxy with extended radio lobes out to 100 kpc reveals recent feeding of the central massive black hole. A system like AWM 4 should have no radio emission at all if only feedback from the cooling hot gas regulates the AGN activity.
Gastaldello F., Buote D.A., Brighenti F., Mathews W.G. (2008). Trouble for AGN Feedback? The Puzzle of the Core of the Galaxy Cluster AWM 4. THE ASTROPHYSICAL JOURNAL LETTERS, 673, L17-L20 [10.1086/527472].
Trouble for AGN Feedback? The Puzzle of the Core of the Galaxy Cluster AWM 4
BRIGHENTI, FABRIZIO;
2008
Abstract
The core of the relaxed cluster AWM 4 is characterized by a unique combination of properties which defy a popular scenario for AGN heating of cluster cores. A flat inner temperature profile is indicative of a past, major heating episode which completely erased the cool core, as testified by the high central cooling time (3 Gyr) and by the high central entropy level (∼60 keV cm2 ). Yet the presence of a 1.4 GHz active central radio galaxy with extended radio lobes out to 100 kpc reveals recent feeding of the central massive black hole. A system like AWM 4 should have no radio emission at all if only feedback from the cooling hot gas regulates the AGN activity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
