5988( 0) - 07/18/95 19:05 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5988 Version: ********** Check-in Date: ********** 1.Proposal Title: IMAGING OF QUASARS IN RICH CLUSTERS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Erica Ellingson Dept. of Astronomy, New Mexico State University CoI: Howard Yee University of Toronto N CoI: Roberto Abraham IoA, Cambridge University N ------------------------------------------------------------------------------------ 6. Abstract We propose to obtain WFPC2 images in 2 colors of rich clusters of galaxies associated with quasars. Our extensive surveys of quasar environments suggest that quasars situated in rich clusters evolve 5--6 times more rapidly than those in poor environments. This evolution is mostly likely tied to the evolution of the clusters themselves. Hence, a cluster harboring a bright quasar at its center is likely to be in a relatively early stage of evolution. A detailed study of these clusters would provide important insights into the relationship between environment and quasar activity, and also the evolution of galaxy clusters and their member galaxies. HST images of these clusters, for which we already have extensive redshift data, will address 3 major scientific goals. First, we can study the morphologies of the cluster galaxies and compare their properties with other high redshift clusters. Ground-based data have indicated that these clusters have lower velocity dispersions, higher blue galaxy fractions, and higher merging fractions, and so may represent a unique population of dynamically young galaxy clusters. Second, we will investigate properties of the host galaxies and the local (<25 kpc) environment of the quasars to test scenarios for triggering AGN activity in these environments. This study may also allow us to investigate the origins of cD galaxies, as these are the most likely host galaxies for these quasars. ------------------------------------------------------------------------------------ 5988( 0) - 07/18/95 19:05 - [ 2] Observations Description ------------------------ We propose WFPC2 observations in two filters of a sample of 3 high redshift galaxy clusters hosting quasars. The sample is chosen to cover a redshift range of 0.4 to 0.6, in clusters as rich as or richer than Abell 1, and have relatively complete redshift data on member galaxies. The filters used depend on the redshift of the clusters. One will be to the red of the 4000Angstrom break, and the other, to the blue. For the red filter, we will use F814W, which approximate rest V or Gunn g. For the blueward filter, to maximize efficiency, we will use F606W for the z>0.5 clusters, and F555W for z<0.5 clusters. These filters approximate rest B or U band photometry. The surface brightness limits required to obtain the necessary morphological and color information will depend on the redshift of the galaxies. Based on actual examples of galaxies at z~0.4 from CHFT HRCam images, we found that in order to discern low surface brightness features that may be tidal debris from interacting galaxies, we need to obtain a S/N ratio of ~ 3 per pixel for surface brightness of 23.5 mag/sq arcsec in R, or I~23.1 mag/sq arcsec. We increase the minimum limit slightly to I=23.3 for the lowest redshift cluster, so as to increase the S/N ratio for background galaxies. To retain the same detection limit for clusters at z~0.6, we require a surface brightness limit of ~23.7 mag/sq arcsec in I, using the (1+z)^-4 dimming law and a small K- correction. For the blue band, we need to detect regions which have relatively young stellar population, requiring surface brightness with typical B-R< 1 mag, or equivalent V magnitude (after consideration for K-correction) surface brightness ranging from 24.3 to 24.9 mag/sq arcsec. Using these considerations and the formulae in the WPC2 Instrument Handbook we require integration times of 113, 63, 63 min for the F814W filter for the quasars at z=0.60, 0.47, and 0.41; and 194 min for the F606W filter for the z=0.60 field; and 176 and 130 min for the F555W filter for the z=0.47 and 0.41 fields, respectively. For computing the orbits, we generally round up for the red filter as it is our primary color, but round down for the blue side filters as we are looking for the bluest regions in the galaxies. As an example, for 3C281, there are 52 minutes of target visibility per orbit with acquisition of guide star and overhead being 12+5 min for the first orbit, and 6+5 for the second. This gives a total of 117 min integration (versus 113 min estimated) for the F814W filter in 3 orbits and 164 min (versus 194 min estimated) for the F606W filter. For the other 3 fields, the numbers of orbits for the red side and blue side filters are: 2 and 4 for 5C2.10, and 2 and 3 for 3C215, giving a grand total of 18 orbits. For calibration, we will need flat fields for the F814W, F606W, and F555W filters. Real Time Justification ----------------------- Using CFHT, we have already obtained cluster galaxy redshifts for 73\ additional fainter objects at a lower completeness level (See Ellingson & Yee 1994). We have additional time assigned (Jan 95) at CFHT to complete our redshift identification for ~90\ all the galaxies in these field that are brighter than $r=22 mag. These quasars are also members of a sample which we are studying for associated metal-line absorption systems (e.g. Ellingson et al. 1994, AJ, 107, 1219). This program involves both ground based observations using the MMT and archival HST FOS observations. The proposed imaging data will allow us to determine the properties of galaxies which cause such absorptions in the quasar spectra. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5988( 0) - 07/18/95 19:05 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5988( 0) - 07/18/95 19:05 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C215 GALAXY,QUASAR,CLUSTER RA=9H 3M 44.16S +/- 1.0", B1950.0 z=0.411 V=18.55 +/- 0.5 B-V=0+/- 0.5 OF GALAXIES DEC=16D 58' 15.70" +/- 1.0" Comments: QUASAR LOCATED IN GALAXY CLUSTER z=0.411 2 5C2.10 GALAXY,QUASAR,CLUSTER RA=10H 52M 35.40S +/- 5.0", J2000.0 z=0.478 V=18.18 +/- 0.5 B-V=0+/- 0.5 OF GALAXIES DEC=48D 40' 06.00" +/- 5.0" Comments: QUASAR LOCATED IN GALAXY CLUSTER z=0.478. Coordinates updated from catalog using STScI finder. Quasar is brightest object near these cordinates. 3 3C281 GALAXY,QUASAR,CLUSTER RA=13H 05M 22.48S +/- 1.0", B1950.0 z=0.600 V=17.02 +/- 0.5 B-V=0+/- 0.5 OF GALAXIES DEC=06D 58' 12.90" +/- 1.0" Comments: QUASAR LOCATED IN GALAXY CLUSTER z=0.600 5988( 0) - 07/18/95 19:05 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Quasar on PC, please maximize exposure time Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 3C215 WFPC2 IMAGE PC1 F814W 1 2100S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 12 3C215 WFPC2 IMAGE PC1 F814W 1 2400S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 13 3C215 WFPC2 IMAGE PC1 F555W 1 2400S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 14 3C215 WFPC2 IMAGE PC1 F555W 1 2400S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 15 3C215 WFPC2 IMAGE PC1 F555W 1 2400S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 5988( 0) - 07/18/95 19:05 - [ 6] Visit: 02 Visit Requirements: ORIENT 170D TO 290D On Hold Comments: Additional Comments: Quasar on PC; area NE of quasar on WFCs Ignore orientation request if it reduces schedulability too much. Maximize exposures please Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 21 5C2.10 WFPC2 IMAGE PC1 F814W 1 2200S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 22 5C2.10 WFPC2 IMAGE PC1 F814W 1 2600S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 23 5C2.10 WFPC2 IMAGE PC1 F555W 1 2600S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 24 5C2.10 WFPC2 IMAGE PC1 F555W 1 2600S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 25 5C2.10 WFPC2 IMAGE PC1 F555W 1 2600S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 26 5C2.10 WFPC2 IMAGE PC1 F555W 1 2600S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 5988( 0) - 07/18/95 19:05 - [ 7] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Quasar on PC; maximize exposure time please Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 31 3C281 WFPC2 IMAGE PC1 F814W 1 2100S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 32 3C281 WFPC2 IMAGE PC1 F814W 1 2400S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 33 3C281 WFPC2 IMAGE PC1 F814W 1 2400S NO SPLIT EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 34 3C281 WFPC2 IMAGE PC1 F606W 1 2400S ------------------------------------------------------------------------------------------------------------------------------------ 35 3C281 WFPC2 IMAGE PC1 F606W 1 2400S ------------------------------------------------------------------------------------------------------------------------------------ 36 3C281 WFPC2 IMAGE PC1 F606W 1 2400S ------------------------------------------------------------------------------------------------------------------------------------ 37 3C281 WFPC2 IMAGE PC1 F606W 1 2400S ------------------------------------------------------------------------------------------------------------------------------------ 5988( 0) - 07/18/95 19:05 - [ 8] Summary Form for Proposal 5988 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements NO SPLIT EXPAND ORIENT 170D TO 290D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C215 5C2.10 3C281 ------------------------------------------------------------------------------------------------------------------------------------