0 Assigned ID: 1128 ----- Attempting Submission 1 (Fri Sep 27 12:46:43 GMT 2019) ----- 0 ----- Attempting Submission 1 (Tue Nov 05 19:09:48 GMT 2019) ----- ----- Attempting Submission 2 (Thu Nov 07 14:15:51 GMT 2019) ----- We have recently discovered a new galaxy cluster at z=0.48 that harbors a massive central galaxy forming stars at a rate of ~150 Msun/yr. This would make it the second most star-forming central galaxy known and a far cry from the typical red-and-dead giant ellipticals that live in the centers of clusters. While star formation has been seen in the centers of relaxed, cool core clusters -- thought to be a residual cooling flow that represents the imbalance between cooling and feedack -- this system represents the only known system at z<1 where star formation is proceeding in the center of a merging galaxy cluster. It is unclear how such a system could come to be, as the current understanding is that relaxedness is a necessary condition for the development of cooling in the intracluster medium. With the proposed-for HST data, we will be able to map out the ongoing star formation and see if it is morphologically more similar to the distribution of cooling intracluster gas or to nearby member galaxies. This will allow us to distinguish between a merger and cooling origin for the star formation. In either case, this system represents a rare phase of galaxy formation, and may provide important clues to the formation of giant elliptical galaxies and the cooling/feedback balance in cluster cores. The goal of this program is to obtain broadband images in F550M and F110W to probe the young and old stellar populations, respectively. In each filter we will obtain 3 exposures to allow removal of cosmic rays. Overall it should be a really straightforward program to execute. We are only interested in the ~15" surrounding our pointing position, so orientation is not important. The PI (McDonald) has significant experience studying star formation in giant elliptical galaxies using ground-based imaging/spectroscopy as well as HST imaging in narrow and broad bands. One of his recent publications summarizes the current status of the cooling flow problem, with a focus on understanding the most star-forming central cluster galaxies known. The co-PI (Somboonpanyakul) is a graduate student working under McDonald who has led the development of the CHiPS survey and initially discovered this galaxy cluster. He is well-versed in optical and X-ray data reduction, and has sufficient time and resources to carry out this program. Galaxies and the IGM Massive Black Holes And Their Host Galaxies 6 false false false false false false false SUPPORTED GALAXY COOLING FLOW ELLIPTICAL EMISSION LINE NEBULA STARBURST TIDAL TAIL YES J2000 J2000 ACS/WFC Imaging No No F550M WFC3/IR Imaging No No F110W POS-TARG DITHER 3.034 LINE false false 3 85.29 ACS-WFC-DITHER-LINE 1 false POS-TARG DITHER DITHER 2 5.183 WFC3-IR-DITHER-LINE true true 5.183 2 41.859 POS-TARG WFC3-IR-DITHER-BLOB 131.859 2 true 1573135993821 /private/var/folders/x1/8vhxbyrs2fzdnd9qzn5z__9h0000gn/T/OPVisit6242753596932967496.xml The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16038 :visit-id "01" :proposal-version -1 :trans-version "20190514" :date "07-Nov-2019 09:13:13.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 852672 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16038 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16038 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2905 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3238 :pcs-gap 0 ) true 1 0 1573135986850 /private/var/folders/x1/8vhxbyrs2fzdnd9qzn5z__9h0000gn/T/OPVisit9769451435603985509.xml The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16038 :visit-id "02" :proposal-version -1 :trans-version "20190514" :date "07-Nov-2019 09:13:06.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1044528 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16038 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16038 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2863 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3238 :pcs-gap 0 ) true 1 0