EVERY BCG WITH A STRONG RADIO AGN HAS AN X-RAY COOL CORE: IS THE COOL CORE-NONCOOL CORE DICHOTOMY TOO SIMPLE?
- Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
The radio active galactic nucleus (AGN) feedback in X-ray cool cores has been proposed as a crucial ingredient in the evolution of baryonic structures. However, it has long been known that strong radio AGNs also exist in 'noncool core' clusters, which brings up the question whether an X-ray cool core is always required for the radio feedback. In this work, we present a systematic analysis of brightest cluster galaxies (BCGs) and strong radio AGNs in 152 groups and clusters from the Chandra archive. All 69 BCGs with radio AGN more luminous than 2 x 10{sup 23} W Hz{sup -1} at 1.4 GHz are found to have X-ray cool cores. BCG cool cores can be divided into two classes: the large cool core (LCC) class and the corona class. Small coronae, easily overlooked at z > 0.1, can trigger strong heating episodes in groups and clusters, long before LCCs are formed. Strong radio outbursts triggered by coronae may destroy embryonic LCCs and thus provide another mechanism to prevent the formation of LCCs. However, it is unclear whether coronae are decoupled from the radio feedback cycles as they have to be largely immune to strong radio outbursts. Our sample study also shows the absence of groups with a luminous cool core while hosting a strong radio AGN, which is not observed in clusters. This points to a greater impact of radio heating on low-mass systems than clusters. Few L {sub 1.4GHz} > 10{sup 24} W Hz{sup -1} radio AGNs (approx16%) host an L {sub 0.5-10keV} > 10{sup 42} erg s{sup -1} X-ray AGN, while above these thresholds, all X-ray AGNs in BCGs are also radio AGNs. As examples of the corona class, we also present detailed analyses of a BCG corona associated with a strong radio AGN (ESO 137-006 in A3627) and one of the faintest coronae known (NGC 4709 in the Centaurus cluster). Our results suggest that the traditional cool core/noncool core dichotomy is too simple. A better alternative is the cool core distribution function, with the enclosed X-ray luminosity or gas mass.
- OSTI ID:
- 21367348
- Journal Information:
- Astrophysical Journal, Vol. 704, Issue 2; Other Information: DOI: 10.1088/0004-637X/704/2/1586; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
BARYONS
DISTRIBUTION FUNCTIONS
FEEDBACK
GALACTIC EVOLUTION
GALAXY CLUSTERS
GHZ RANGE 01-100
LUMINOSITY
MASS
X-RAY GALAXIES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELEMENTARY PARTICLES
EVOLUTION
FERMIONS
FREQUENCY RANGE
FUNCTIONS
GALAXIES
GHZ RANGE
HADRONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES