We present new ultraviolet , optical , and X-ray data on the Phoenix galaxy cluster ( SPT-CLJ2344-4243 ) .
Deep optical imaging reveals previously-undetected filaments of star formation , extending to radii of \sim 50–100 kpc in multiple directions .
Combined UV-optical spectroscopy of the central galaxy reveals a massive ( 2 \times 10 ^ { 9 } M _ { \odot } ) , young ( \sim 4.5 Myr ) population of stars , consistent with a time-averaged star formation rate of 610 \pm 50 M _ { \odot } yr ^ { -1 } .
We report a strong detection of O vi \lambda \lambda 1032,1038 , which appears to originate primarily in shock-heated gas , but may contain a substantial contribution ( > 1000 M _ { \odot } yr ^ { -1 } ) from the cooling intracluster medium .
We confirm the presence of deep X-ray cavities in the inner \sim 10 kpc , which are amongst the most extreme examples of radio-mode feedback detected to date , implying jet powers of 2 - 7 \times 10 ^ { 45 } erg s ^ { -1 } .
We provide evidence that the AGN inflating these cavities may have only recently transitioned from “ quasar-mode ” to “ radio-mode ” , and may currently be insufficient to completely offset cooling .
A model-subtracted residual X-ray image reveals evidence for prior episodes of strong radio-mode feedback at radii of \sim 100 kpc , with extended “ ghost ” cavities indicating a prior epoch of feedback roughly 100 Myr ago .
This residual image also exhibits significant asymmetry in the inner \sim 200 kpc ( 0.15R _ { 500 } ) , reminiscent of infalling cool clouds , either due to minor mergers or fragmentation of the cooling ICM .
Taken together , these data reveal a rapidly evolving cool core which is rich with structure ( both spatially and in temperature ) , is subject to a variety of highly energetic processes , and yet is cooling rapidly and forming stars along thin , narrow filaments .