! File: 4683C.PROP ! Database: PEPDB ! Date: 22-FEB-1994:22:19:49 coverpage: title_1: EVOLUTION OF GALAXIES IN INTERMEDIATE REDSHIFT CLUSTERS : IMAGING title_2: OF ABELL 665- CYC3 SUPPLEMENTAL sci_cat: GALAXIES & CLUSTERS sci_subcat: EVOLUTION/COSMOLOGY proposal_for: GO pi_fname: MARIJN pi_lname: FRANX pi_inst: KAPTEYN ASTRONOMICAL INSTITUTE pi_country: NETHERLANDS hours_pri: 2.20 num_pri: 2 wf_pc: Y off_fname: PIET off_mi: C off_lname: VAN DER KRUIT off_title: CHAIRMAN off_inst: 6830 off_addr_1: KAPTEYN ASTRONOMICAL INSTITUTE off_addr_2: UNIVERSITY OF GRONINGEN off_addr_3: P.O. BOX 800 off_city: GRONINGEN off_zip: 9700 AV off_country: NETHERLANDS off_phone: 011 31 50 634053 ! end of coverpage abstract: line_1: One of the more fundamental problems in current astronomy is that of galaxy line_2: evolution. We still do not have good constraints on how galaxy densities, line_3: types, and luminosities evolve with redshift. Most studies until now have used line_4: only photometric and spectrophotometric information to derive 'spectral' line_5: classifications and luminosities. Whereas these methods will remain essential line_6: to understanding evolution, they are insufficient for a unique interpretation line_7: of the data. I have started a ground-based program to measure dynamical line_8: parameters of galaxies in intermediate redshift clusters. I have successfully line_9: measured velocity dispersions, and in some cases, rotational velocities. These line_10: dynamical data are a fundamental step forward towards quantifying the effects line_11: of 'passive evolution', mergers, starburst, etc. For a proper interpretation, line_12: morphological information on the studied galaxies is necessary. I propose HST line_13: observations of the well-studied cluster A 665 at z=0.18 to obtain the line_14: necessary morphological information. ! ! end of abstract general_form_proposers: lname: FRANX fname: MARIJN title: PI inst: KAPTEYN ASTRONOMICAL INSTITUTE country: NETHERLANDS ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: I propose to take WFPC images of Abell 665, a well studied line_2: cluster at a redshift of 0.18. This cluster is one of the line_3: clusters for which the Sunyaev-Zel'dovitch effect has been line_4: established$^1$, and a good dataset of spectra and radial line_5: velocities are available$^{2,3}$. I have already measured line_6: internal velocity dispersions for a sample of galaxies, line_7: and I will extend this sample in the near future. The HST line_8: images will allow a good morphological classification of line_9: the studied galaxies, essential before they can be used line_10: for the analysis. Although it would be of great interest line_11: to have very detailed information on the galaxies, it is line_12: clearly beyond the means of the current instruments to go line_13: beyond a classification of the galaxies; thus images will line_14: be taken in only one passband. Because of the large area line_15: that needs to be surveyed it is optimal to use the WF, line_16: despite the slightly performance due to the large pixel line_17: scale. Imaging with the PC would be too time consuming. line_18: It will be necessary to observe two separate fields to line_19: cover all the galaxies of the ground based program. line_20: \bigskip\parindent=0pt line_21: $^1$ Birkinshaw, Hughes and Arnaud, 1991, Ap. J. in press.\par line_22: $^2$ Oegerle, Fitchett, Hill, Hintzen, 1991, preprint.\par line_23: $^3$ Birkinshaw, private communication.\par ! question: 4 section: 1 line_1: The need for HST images is obvious if there were no spherical aberration: it line_2: would provide us with 2D photometry comparable to the ground-based data that line_3: can be achieved on Coma. Thus detailed structural studies would be possible. line_4: The spherical aberration reduces the quality of the data, but still allows for line_5: a good morphological classification of the galaxies, which is the main purpose line_6: of the current proposal. It is expected that fine structure caused by spiral line_7: arms, and mergers, can be recognized easily. It will be especially interesting line_8: to see if there is any evidence for a merger in the image of the large, line_9: post-starburst galaxy shown in Figure 1b of the scientific justification. line_10: There is no other such galaxy to date for which this type of kinematic data line_11: exists, and thus the HST images would be particularly useful. line_12: The power of the current HST for morphological studies has been demonstrated line_13: in a recent analysis by King \etal$^{1}$: These authors showed that several line_14: deconvolution techniques can produce useful images out to a surface line_15: brightnesses at which the Signal to Noise ratio is 10. They showed line_16: specifically how images with moderate integration times enable classification line_17: at low-intermediate redshift (around 0.2). Thus the proposed project is one line_18: of the types that HST still can do well, and are impossible to do from the line_19: ground. The reason is that the core of the PSF of HST (which is very narrow, line_20: but has not much energy) still provides the qualitative information on the line_21: galaxy structure. This information is completely absent in ground-based work. line_22: It will be harder to derive accurate quantitative information on these line_23: galaxies, as these will depend on the quality of the PSF. ! question: 5 section: 1 line_1: As imaging in only one color is requested, I have chosen the passband line_2: which will produce the highest expected S/N. This is the ``R'' filter F702W. line_3: It has almost twice the throughput of other filters in the V to I line_4: wavelengths, mainly because of its width. line_5: A typical surface brightness for an elliptical at an effective radius is line_6: between 20.6 and 22.2 line_7: in R (K corrected). A 2000 sec exposure is expected to give a S/N of line_8: about 13 at a surface brightness of 22.2 mag/arcsec$^2$. line_9: Two exposures will be needed to verify the reality of the observed line_10: structures. These images will go deep enough to detect structures in line_11: disk galaxies to 1-2 effective radii. The integration times are optimal line_12: in the sense that the sky-photon noise will be comparable to the readout noise. ! question: 6 section: 1 line_1: ! question: 7 section: 1 line_1: The data analysis consists of 2 parts: the deconvolution for the morphological line_2: classification and the measurement of global photometric paramters. line_3: 1 Deconvolution : Recent tests on field galaxies have shown that the line_4: flux-conserving CLEAN method devised by Keel provides good line_5: results$^{1,2}$. This method can reconstruct the galaxy images as long as the line_6: S/N is higher than 10. The CLEAN algorithm works so well because of the strong line_7: peak in the PSF. Other techniques have been shown to give similar results. For line_8: the morphological classification it is not necessary to go beyond this step: line_9: the deconvolved images should be sufficient to type the galaxies. line_10: 2 Global Parameters : The global parameters like effective radius, surface line_11: brightness, and bulge to disk ratio will be derived directly from the data, line_12: i.e. bypassing the deconvolution. This can be achieved by minimization of the line_13: residuals of the convolved model with the data. The advantage of this method line_14: is that it allows for a much better determination of the errors (error line_15: estimates for deconvolved images are very complicated). The fitting procedure line_16: is very similar to procedures to determine velocity dispersions for galaxies: line_17: THe problem is transformed into Fourier space (a minimization in real space is line_18: the same as a minimization in Fourier space). Now the convolution with the line_19: PSF is a simple multiplication. The model parameters can be determined by a line_20: non-linear least-squares fit. The correlation matrix gives directly the line_21: errors and correlations of the fit. line_22: 1. King et al, 1991, AJ 102, 1553.\par 2. Keel 1988, ApJ 329, 532. ! question: 8 section: 1 line_1: Any additional comments go here. ! question: 9 section: 1 line_1: A description of any previous HST data goes here. ! question: 10 section: 1 line_1: I am a full professor at the Kapteyn Institute, at the University of Groningen. line_2: The institute has provided me with a powerful workstation, and is able to line_3: fund students and postdocs for this research. ! !end of general form text general_form_address: lname: FRANX fname: MARIJN category: PI addr_1: KAPTEYN ASTRONOMICAL INSTITUTE addr_2: UNIVERSITY OF GRONINGEN addr_3: P.O. BOX 800 city: GRONINGEN zip: 9700 AV country: NETHERLANDS phone: 011 31 50 634067 telex: 53572 STARS NL ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: ABELL0665-POS1 descr_1: F,404 pos_1: RA= 08H26M09.77S +/-0.1S, pos_2: DEC= +66D00'31.2" +/- 0.1", equinox: 1950 rv_or_z: Z= 0.18 comment_1: THIS POSITION IS REALLY ACCU- comment_2: RATE. B1950 COORDINATES. comment_3: WHEN CENTERED ON THIS POSI- comment_4: TION, BRIGHT STAR IN comment_5: SOUTHERN FIELD, WHICH WILL comment_6: SATURATE CCD. OTHER BRIGHT STARS comment_7: FORCE CLOCKS=YES fluxnum_1: 1 fluxval_1: SURF-BKG(R) = 19 +/- 1.0 ! targnum: 2 name_1: ABELL0665-POS2 descr_1: F,404 pos_1: RA= 08H26M29.85S +/-0.1S, pos_2: DEC= +66D00'11.1" +/- 0.1", equinox: 1950 rv_or_z: Z= 0.18 comment_1: THIS POSITION IS REALLY ACCU- comment_2: RATE. B1950 COORDINATES. comment_3: THIS FIELD DOES NOT CONTAIN comment_4: BRIGHT STAR(S). fluxnum_1: 1 fluxval_1: SURF-BKG(R) = 19 +/- 1.0 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 sequence_1: DEFINE ABE targname: ABELL0665-POS2 config: WFC opmode: IMAGE aperture: WFALL-FIX sp_element: F702W time_per_exp: 1400S s_to_n: 20 fluxnum_1: 1 priority: 2 param_1: CR-SPLIT=0.0, param_2: CR-TOLERANCE=0.0, param_3: PRE-FLASH=YES, param_4: PURGE=YES req_2: POS TARG +10,-10 ; req_3: CYCLE 3 comment_1: ORIENTATIONS 96 +-6, 186 +- 6 AND comment_2: 276 +- 10 ARE ALSO ALLOWED. comment_3: THIS IS THE LOWER PRIORITY EXPOSURE. comment_4: WHEN BOTH FIELDS PLANNED comment_5: CONSECUTIVELY, DO THIS FIELD FIRST. ! linenum: 2.000 sequence_1: DEFINE ABE targname: ABELL0665-POS1 config: WFC opmode: IMAGE aperture: WFALL-FIX sp_element: F702W num_exp: 1 time_per_exp: 1400S s_to_n: 20 fluxnum_1: 1 priority: 1 param_1: CR-SPLIT=0.0, param_2: CR-TOLERANCE=0.0, param_3: PRE-FLASH=YES, param_4: CLOCKS=YES req_2: POS TARG +10,-10 ; req_3: CYCLE 3 comment_1: ORIENTATIONS 96 +-10, 186 +- 10 AND comment_2: 276 +- 10 ARE ALSO ALLOWED. THIS IS comment_3: THE MOST IMPORTANT EXPOSURE. DO NOT comment_4: USE WFC WITHIN ONE HOUR AFTER THIS comment_5: EXPOSURE. WHEN BOTH FIELDS PLANNED comment_6: CONSECUTIVELY, DO FIELD 2 FIRST. ! linenum: 3.000 sequence_1: USE ABE num_exp: 3 req_1: CYCLE 3 ! ! end of exposure logsheet ! No scan data records found