A CHANDRA STUDY OF TEMPERATURE SUBSTRUCTURES IN INTERMEDIATE-REDSHIFT GALAXY CLUSTERS
By analyzing the gas temperature maps created from the Chandra archive data, we reveal the prevailing existence of temperature substructures on {approx}100 h{sup -1}{sub 70} kpc scales in the central regions of nine intermediate-redshift (z {approx} 0.1) galaxy clusters, which resemble those found i...
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Veröffentlicht in: | The Astrophysical journal 2009-08, Vol.700 (2) |
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Sprache: | eng |
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Zusammenfassung: | By analyzing the gas temperature maps created from the Chandra archive data, we reveal the prevailing existence of temperature substructures on {approx}100 h{sup -1}{sub 70} kpc scales in the central regions of nine intermediate-redshift (z {approx} 0.1) galaxy clusters, which resemble those found in the Virgo and Coma Clusters. Each substructure contains a clump of hot plasma whose temperature is about 2-3 keV higher than the environment, corresponding to an excess thermal energy of {approx}10{sup 58}-10{sup 60} erg per clump. If there were no significant nongravitational heating sources, these substructures would have perished in 10{sup 8}-10{sup 9} yr due to thermal conduction and turbulent flows, whose velocity is found to range from about 200 to 400 km s{sup -1}, we conclude that the substructures cannot be created and sustained by inhomogeneous radiative cooling. We also eliminate the possibilities that the temperature substructures are caused by supernova explosions, or by the nonthermal X-ray emission due to the inverse-Comptonization of the cosmic microwave background photons. By calculating the rising time of active galactic nucleus (AGN)-induced buoyant bubbles, we speculate that the intermittent AGN outbursts ({>=}10{sup 60} erg per burst) may have played a crucial role in the formation of the high-temperature substructures. Our results are supported by the recent study of McNamara and Nulsen, posing a tight observational constraint on future theoretical and numerical studies. |
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ISSN: | 0004-637X 1538-4357 |
DOI: | 10.1088/0004-637X/700/2/1161;COUNTRYOFINPUT:INTERNATIONALATOMICENERGYAGENCY(IAEA) |