Review Article

Evidence for AGN Feedback in Galaxy Clusters and Groups

Figure 6

(a) High-contrast hardness ratio map of the galaxy cluster Hydra A obtained by dividing a 1.5–7.5 keV image by a 0.3–1.5 keV image. Regions in black are indicative of low temperature gas, indicating the presence of low-entropy filaments. Overlaid in green are the sectors used to study the spectral properties of the cool gas (located between radii ~70–150 kpc). Gitti et al. [120] extracted the spectra in these sectors and compared two different spectral models: a single-temperature plasma “1T’’ model, and a “2T’’ model which includes a second thermal emission component. The F statistics for the spectral fitting improvement over the single-phase model indicate that the addition of a second thermal component is most significant in sectors SSE, NNW, NNE, and ENE, thus providing evidence for the presence of multiphase gas in agreement with the hardness ratio map. Adapted from Gitti et al. [120]. (b) Metallicity map showing the central of Hydra A. Brighter regions represent a higher metallicity. The color scale of the metallicity (in solar units) is as follows: white: , yellow: , orange: , red: , blue: , and black: . The 1.4 GHz radio emission is shown by the black contours. The green elliptical regions indicate the position of the inner cavities. Adapted from Kirkpatrick et al. [119]. In both panels are overlaid the white contours outlining the 330 MHz radio emission from Lane et al. [164].
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