Residual Cooling and Persistent Star Formation amid AGN Feedback in
  Abell 2597
  New Chandra X-ray and Herschel FIR observations enable a multiwavelength
study of active galactic nucleus (AGN) heating and intracluster medium (ICM)
cooling in the brightest cluster galaxy of Abell 2597. The new Chandra
observations reveal the central < 30 kiloparsec X-ray cavity network to be more
extensive than previously thought, and associated with enough enthalpy to
theoretically inhibit the inferred classical cooling flow. Nevertheless, we
present new evidence, consistent with previous results, that a moderately
strong residual cooling flow is persisting at 4%-8% of the classically
predicted rates in a spatially structured manner amid the feedback-driven
excavation of the X-ray cavity network. New Herschel observations are used to
estimate warm and cold dust masses, a lower-limit gas-to-dust ratio, and a star
formation rate consistent with previous measurements. The cooling time profile
of the ambient X-ray atmosphere is used to map the locations of the
observational star formation entropy threshold as well as the theoretical
thermal instability threshold. Both lie just outside the < 30 kpc central
region permeated by X-ray cavities, and star formation as well as ionized and
molecular gas lie interior to both. The young stars are distributed in an
elongated region that is aligned with the radio lobes, and their estimated ages
are both younger and older than the X-ray cavity network, suggesting both
jet-triggered as well as persistent star formation over the current AGN
feedback episode. Bright X-ray knots that are coincident with extended Ly-alpha
and FUV continuum filaments motivate a discussion of structured cooling from
the ambient hot atmosphere along a projected axis that is perpendicular to
X-ray cavity and radio axis. We conclude that the cooling ICM is the dominant
contributor of the cold gas reservoir fueling star formation and AGN activity
in the Abell 2597 BCG.
