16494( 5) - 17-Feb-2021 16:20:38 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16494 Version: 5 Check-in Time: 17-Feb-2021 16:20:38 STScI Edit Number: 3 Title Re-Testing the Limits of AGN Feedback in Central Cluster Galaxies ------------------------------------------------------------------------------------ Type Cycle GO/DD 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Michael A. McDonald Massachusetts Institute of Technology Y CoI: Michael S. Calzadilla Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ Abstract In the cores of galaxy clusters, the hot intracluster medium should cool rapidly, leading to "cooling flows" of order ~100-1000 Msun/yr. Our current picture is that AGN feedback is responsible for preventing these runaway cooling events, leading to more typical star formation rates of ~1-10 Msun/yr in the centers of relaxed, cool core clusters. However, recent work suggests that feedback may saturate in the most massive clusters, leading to a cooling imbalance in the most extreme systems. In this proposal, we target one of the most star-forming central cluster galaxies in the Universe (with the other 5 having already been observed), which is forming stars at nearly the classical cooling flow prediction. We will obtain narrow-band [O II] imaging using the ACS ramp filter on this cluster, allowing us to probe the development of thermal instabilities as gas condenses out of the hot phase and ultimately forms stars. Combining these data with the larger sample sample of six massive clusters provides an opportunity to test the limits of AGN feedback, where cooling does not appear to be significantly suppressed. Three of these six clusters also harbor central QSOs, allowing us to probe the different effects of mechanical (radio-mode) and radiative (quasar-mode) feedback in the inner regions of clusters. As the six most star-forming central cluster galaxies, these will make stunning and inspiring images and have tremendous legacy value, as recent Chandra+ALMA and future JWST targets. NOTE: This is a reobservation of a failed visit for a larger approved program. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our goal is to obtain a deep, high-angular resolution maps of [O II]3726, 3729 for a single giant elliptical galaxy, following in methodology from HST Proposals 15315 and 15661. This is possible using the ramp filters on ACS, which provide narrow-band filters over the range 3700-10700A. At the redshift of our targets the filter width is ~120A. The width of this filter means that we will (easily) obtain both lines in the [O II] doublet, while avoiding any other strong lines. Given the inherent challenge in flux calibrating and flat fielding HST ramp filter data, achieving a reliable flux map would be challenging even with perfect knowledge of the intrinsic extinction. We will use in-hand broadband filter observations to subtract continuum emission, which will contribute significantly to the narrow bandpass. Broadband filters have been chosen to bracket the 4000A break and avoid emission from Balmer lines and [O III] (5007A). These broadband filters are a factor of ~10x 16494( 5) - 17-Feb-2021 16:20:38 - [ 2] wider than the narrow-band filter, providing similar sensitivity to the continuum in a single orbit as we achieve over 8 exposures in the narrow band. Combining the two bands bracketing the [OII] line, we will have a factor of 5x deeper exposure in the continuum, compared to the narrow-band exposure. Without these deep continuum images, we would add significant amounts of noise during the continuum-subtraction procedure, reducing the effective depth of our narrow-band images. ------------------------------------------------------------------------------------ 16494( 5) - 17-Feb-2021 16:20:38 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RXJ1532.9+30 CLUSTER OF GALAXIES, RA=15H32M53.7777S, J2000 V = 18.7 21 COOLING FLOW, EMISSION DEC=+30D20'59.37" LINE NEBULA, NUCLEUS, STAR FORMING REGION Reference Frame: Other: NED ------------------------------------------------------------------------------------------------------------------------------------ 16494( 5) - 17-Feb-2021 16:20:38 - [ 4] Visit: 01 (RXJ1532-OII-v1) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RXJ1532.9+3 ACS/WFC ACCUM WFC1-MRAM FR505N 5080 1 2000 S 021 P see below (2577 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 RXJ1532.9+3 ACS/WFC ACCUM WFC1-MRAM FR505N 5080 1 2000 S POS TARG 0.247, 0.094 021 P see below (2650 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ RXJ1532.9+3021 1 ACS/WFC ACCUM WFC1-MRA FR505N 5080 none none none none 1 2577.0 S MP RXJ1532.9+3021 2 ACS/WFC ACCUM WFC1-MRA FR505N 5080 none none none none 2 2650.0 S MP 16494( 5) - 17-Feb-2021 16:20:38 - [ 5] Visit: 02 (RXJ1532-OII-v2) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RXJ1532.9+3 ACS/WFC ACCUM WFC1-MRAM FR505N 5080 1 2000 S POS TARG 0.124, 0.232 021 P see below (2577 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 RXJ1532.9+3 ACS/WFC ACCUM WFC1-MRAM FR505N 5080 1 2000 S POS TARG -0.124, 0.138 021 P see below (2650 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ RXJ1532.9+3021 1 ACS/WFC ACCUM WFC1-MRA FR505N 5080 none none none none 1 2577.0 S MP RXJ1532.9+3021 2 ACS/WFC ACCUM WFC1-MRA FR505N 5080 none none none none 2 2650.0 S MP 16494( 5) - 17-Feb-2021 16:20:38 - [ 6] Summary Form for Proposal 16494 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1-MRAMP ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG -0.124, 0.138, POS TARG 0.124, 0.232, POS TARG 0.247, 0.094 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements FR505N ------------------------------------------------------------------------------------------------------------------------------------ Target Names RXJ1532.9+3021 ------------------------------------------------------------------------------------------------------------------------------------