Spitzer Space Telescope - General Observer Proposal #50492 Constraining the power output of central galaxies into cluster cores Principal Investigator: Alastair Edge Institution: Durham University Technical Contact: Alastair Edge, Durham University Co-Investigators: Richard Wilman, University of Oxford Andrew Fabian, University of Cambridge Hans Bohringer, MPE Christopher O'Dea, Rochester Mark Swinbank, Durham University Stefi Baum, Rochester Alice Quillen, Rochester Jaehong Park, Rochester Carolin Crawford, University of Cambridge Roderick Johnstone, University of Cambridge Philippe Salome, IRAM, Gernoble George Privon, Rochester Eiichi Egami, University of Arizona Science Category: galaxy clusters and groups(low-z) Observing Modes: IracMap MipsPhot Hours Approved: 6.8 Abstract: The cores of clusters of galaxies are now recognised to be amongst the most dynamic environments known. The high pressure and density of the intracluster medium in the centre of the most massive clusters of galaxies provides a number of astrophysical puzzles. Can AGN provide all of the energy required to prevent large-scale cooling of gas in a cluster core? How long to AGN exist in their active phase? Do all brightest galaxies in cluster cores have an active phase? This proposal draws on results from two programmes that are about to complete data collection. The first is the ESO X-ray Cluster Elliptical Spectral Survey, EXCESS, which is a VLT programme of 446 spectra of every brightest cluster galaxy in the REFLEX X-ray cluster sample. This investment of 192 hours of VLT time has revealed the largest sample of optically line luminous objects known to date. The second program is P30659 (PI O'Dea) that has targeted 63 optically line luminous BCGs in the northern hemisphere and has clearly identified that the most extreme objects show evidence for strong star-formation and/or active galaxy. We propose to observe the 21 optically line luminous EXCESS BCGs with IRAC to provide a definitive sample of these rare objects. These data will inform future HST, APEX, VLT, ALMA and JWST observations of these enigmatic objects. We have already made 12 new CO detections from newly identified EXCESS BCGs with the IRAM 30m telescope and ancipate that this optical spectral library will be the basis of many multi-wavelength studies in the next decade. We request IRAC and MIPS 24um observations as the observations of the O'Dea sample clearly show an excess at 8 and 24um that correlates well with the fluxes at longer wavelengths.