17536( 4) - 07-Jun-2024 20:00:12 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17536 Version: 4 Check-in Time: 07-Jun-2024 20:00:12 STScI Edit Number: 1 Title Probing the Cool, Warm, and Hot Gas at the Center of the Perseus Cluster with Deep Far-Ultraviolet Spectroscopy ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Sylvain Veilleux University of Maryland Y CoI: Prof. Andrew C. Fabian University of Cambridge N CoI: Dr. Richard Mushotzky University of Maryland N CoI: Dr. Christopher S. Reynolds University of Maryland N ------------------------------------------------------------------------------------ Abstract The Perseus Cluster is an ideal laboratory to study the physics of radio-mode AGN feedback which prevents large-scale cooling flows and prodigious star formation at the centers of galaxy clusters. Remarkably, the engine at the heart of the Perseus Cluster, the jetted AGN NGC 1275, has never been spectroscopically observed below 1500 A with the high-resolution grating of COS. This is truly a missed opportunity. This spectral region is rich in spectroscopic diagnostics of the neutral, low-ionization, and high-ionization gas that sample a temperature range (10^4-10^7 K) largely inaccessible to the optical and X-rays. COS is an order of magnitude more sensitive than the previously used FOS and STIS. We propose to obtain a deep COS G130M spectrum of this object covering 1140-1430 A to study the central AGN, its outflow, and the multi-phase circumgalactic and intracluster media along the light of sight to the core of the Perseus Cluster. The new data will allow us to derive the ionization, total column densities, metal abundances, and locations of metal-line absorbers from the wind and circumgalactic medium. The strengths and widths of the emission lines from the cooling intracluster medium, including [Fe XXI] 1354, will be measured with unprecedented precision and compared with the Hitomi X-ray measurements as well as predictions of the ionization state and turbulent pressure support in simulations of AGN feedback in clusters. Finally, the new data will be compared with a contemporaneous (<1 week) optical spectrum and on-going monitoring in the gamma-rays, high-frequency radio, hard X-rays, and optical to test recent claims that SMBH fueling regulates jet power in this system. ------------------------------------------------------------------------------------ Observations Description ------------------------ We requested and were allocated 8 orbits to observe NGC 1275, the central galaxy in the Perseus cluster with COS G130M. The RA and DEC coordinates of NGC 1275 are in the ICRS reference frame and taken from PID 12260 (PI Johnstone); they have been verified using the finding chart generated by the Target Confirmation tool of APT. These coordinates are those of the VLBA radio centroid and are therefore accurate to << 0.1". For each visit, we first use ACQ/IMAGE to obtain a NUV image of the field and center the aperture on the intensity peak. For this procedure, we follow the same method as in HST PID 12260, making use of MIRRORB since NGC 1275 is too bright for MIRRORA: it has a flux of 3.2E-15 erg/cm/cm/s/A at 2300 A and 17536( 4) - 07-Jun-2024 20:00:12 - [ 2] 3.0E-15 erg/cm/cm/s/A at 1380 A within the COS aperture (listed under "Other fluxes" in the target description). The exposure time of 60 seconds for ACQ/IMAGE is generous and results in S/N of 44 assuming NGC 1275 is approximately a point source in the NUV (S/N = 11 in the most pessimistic / unrealistic case where the source entirely fills the 1.25" aperture). For the spectroscopic observations, we request the cenwave = 1291 A setting with both segments A and B to capture redshifted Si II 1190/1193, Si III 1206, Ly-alpha, Si II 1260, O I 1302, Si II 1304, C II 1334, Si IV 1393/1402, and [Fe XXI] 1354 from the AGN and ISM/CGM/ICM of NGC 1275 / Perseus Cluster (z = 0.0176). Following the COS2025 policies, we only use FP-POS = 3 and 4 to get equal exposures for segments A and B. The observations are split into two visits of 4 orbits with a single long exposure per orbit changing the FP-POS value for each orbit to reduce the fixed pattern noise. This observing strategy minimizes the overhead and maximize the on-target exposure time, and thus S/N. All of the observations are done in TIME-TAG mode. This temporal sampling will allow us to exclude poor quality data and get improved thermal correction and background removal. For simplicity and to guard against the (unlikely) possibility that our targets are more than ~50% brighter than expected, we set buffer-time = exposure-time. According to the Bright Object Tool (BOT), there are no bright sources near our targets that could cause a problem for COS. ------------------------------------------------------------------------------------ 17536( 4) - 07-Jun-2024 20:00:12 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC1275-CENT GALAXY, COOLING FLOW, RA=03H19M48.1601S +/- 0.1", J2000 V = 16.7 3.2E-15 erg/cm/cm/s/A at 2300 ER NUCLEUS, QSO, RADIO DEC=+41D30'42.11" +/- 0.1" A and 3.0E-15 erg/cm/cm/s/A at 1380 A GALAXY within COS aperture. Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 9.971237766405197E-6 -1.9799995243374724E-4 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17536( 4) - 07-Jun-2024 20:00:12 - [ 4] Visit: 01 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 NGC1275-CEN COS/NUV ACQ/IMA PSA MIRRORB 1 60 S (60 TER GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2340, FLASH=YES, 1 2340 S TER G FP-POS=3, SEGMENT=BOTH see below (2236 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2760, FLASH=YES, 1 2760 S TER G FP-POS=4, SEGMENT=BOTH see below (2605 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2760, FLASH=YES, 1 2760 S TER G FP-POS=3, SEGMENT=BOTH see below (2605 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2760, FLASH=YES, 1 2760 S TER G FP-POS=4, SEGMENT=BOTH see below (2605 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC1275-CENTER 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE NGC1275-CENTER 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2236.0 S G NGC1275-CENTER 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2605.0 S G NGC1275-CENTER 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 2605.0 S G NGC1275-CENTER 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 2605.0 S G 17536( 4) - 07-Jun-2024 20:00:12 - [ 5] Visit: 02 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 NGC1275-CEN COS/NUV ACQ/IMA PSA MIRRORB 1 60 S (60 TER GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2340, FLASH=YES, 1 2340 S TER G FP-POS=3, SEGMENT=BOTH see below (2236 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2760, FLASH=YES, 1 2760 S TER G FP-POS=4, SEGMENT=BOTH see below (2605 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2760, FLASH=YES, 1 2760 S TER G FP-POS=3, SEGMENT=BOTH see below (2605 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1275-CEN COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=2760, FLASH=YES, 1 2760 S TER G FP-POS=4, SEGMENT=BOTH see below (2605 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC1275-CENTER 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE NGC1275-CENTER 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2236.0 S G NGC1275-CENTER 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2605.0 S G NGC1275-CENTER 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 2605.0 S G NGC1275-CENTER 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 2605.0 S G 17536( 4) - 07-Jun-2024 20:00:12 - [ 6] Summary Form for Proposal 17536 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=2340, BUFFER-TIME=2760, FLASH=YES, FP-POS=3, FP-POS=4, SEGMENT=BOTH ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC1275-CENTER ------------------------------------------------------------------------------------------------------------------------------------