12480( 2) - 29-Jun-2011 15:52:43 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12480 Version: 2 Check-in Time: 29-Jun-2011 15:52:43 STScI Edit Number: 0 Title Characterizing a gravitational lens in the molecular Einstein ring SMG 18423+5938 ------------------------------------------------------------------------------------ Type Cycle GO 19 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Chris Carilli Associated Universities, Inc. CoI: Dr. Jean-Francois Lestrade Observatoire de Paris N CoI: Dr. Manuel A Aravena Associated Universities, Inc. Y CoI: Dr. Karun Thanjavur Canada-France-Hawaii Telescope Corporation N CoI: Prof. Jean-Paul Kneib Laboratoire d'Astrophysique de Marseille Y CoI: Dr. Dominik A. Riechers California Institute of Technology N CoI: Dr. Fabian Walter Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Dr. Frank Bertoldi Max-Planck-Institut fur Radioastronomie N CoI: Prof. Alain Omont CNRS, Institut d'Astrophysique de Paris N ------------------------------------------------------------------------------------ Abstract We propose a single orbit exposure of the strongly lensed submm galaxy (SMG), MM18423+5938, using WFC3 110W. MM1842 is the brightest SMG with a published spectroscopic redshift (z = 3.9296), and has an apparent star formation rate of order 1e4 Mo/yr. Recent EVLA observations reveal a complete Einstein ring for the CO emission, confirming the strong lensing hypothesis for MM1842. Using the CFHT, we have identified the lensing galaxy at the center of the CO ring, with z_phot ~ 1.0. MM1842 is the archetype, and best studied, of the new population of strongly lensed SMGs that have recently been identified in shallow, wide field submm surveys. These systems represent the formation of massive galaxies at high redshift in luminous starburst events. MM1842 presents a unique opportunity to study the physical processes involved in early galaxy formation at unprecedented physical resolution. The goal of this modest HST request is to obtain detailed information on the stellar distribution in the lensing galaxy. Such information is fundamental to accurate lens modeling of the system, as has been clearly demonstrated with the CASTLES HST survey. In parallel, we are performing high resolution imaging (0.1") of the very luminous CO, atomic fine structure line, and dust continuum emission from MM1842 with the EVLA and IRAM PdBI. Using the lens model, we can then trace back the gas distribution and dynamics in the source-plane at an effective physical resolution approaching 100pc. The proposed HST observations are crucial to constrain the lens model, and thereby enable a truly breath-taking, high physical resolution study of massive galaxy formation in the early Universe. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose a 1 orbit exposure with WFC3/F110W to image the strong gravitational lens system MM1842. We are aiming to a point source sensitivity is 27.15 AB (4?). The goal is to obtain detailed information on the stellar distribution in the lensing galaxy at z ? 1. Such information is fundamental to improve the lens 12480( 2) - 29-Jun-2011 15:52:43 - [ 2] model for the system, enabling the accurate lens inversion studies discussed above. Even with this modest time request, these data will provide a high significance detection of the integrated emission from the lensing galaxy, which, combined with the superb spatial resolution (? 0.15Ó), will result in a precise determination of the lensing galaxy stellar distribution. Our current imaging suggests that the lensing galaxy is about 1Ó in extent, which is consistent with the expected size of such a lensing galaxy (? 8kpc; Langston et al. 1990), although this is complicated by the seeing limitations of the current ground based images. The light should then e distributed over about 40 diffraction limited resolution elements of the HST. At the proposed sensitivity, we should detect the light over this entire area, and obtain accurate measures of the position, ellipticity, orientation, and light profile of the galaxy. The sensitive imaging may also reveal substructure in the field (satellite galaxy, faint companions) which would also be critical to the lens model. Indeed, such substructure is already suggested by the presence of the brighter galaxy 4Ó to the north with a similar photometric redshift. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- None ------------------------------------------------------------------------------------ 12480( 2) - 29-Jun-2011 15:52:43 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 MM18423+5938 GALAXY, EINSTEIN RING, RA=18H42M22.2900S +/- 0.1", J2000 V = 26.3 +/- 0.4 J (AB) = 21.8; H ELLIPTICAL, DEC=+59D38'29.50" +/- 0.1" (AB)=21.2 GRAVITATIONAL LENS, HIGH REDSHIFT GALAXY, ULTRALUMINOUS IR GAL Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 12480( 2) - 29-Jun-2011 15:52:43 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 1.716 Line_Spacing 1.095 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO Pattern_Comments: We enlarge by a factor of 3 the default pattern - thus keeping the sub-pixel dithering. ------------------------------------------------------------------------------------------------------------------------------------ 12480( 2) - 29-Jun-2011 15:52:43 - [ 5] Visit: 01 Visit Requirements: PCS MODE FINE 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MM18423+593 WFC3/IR MULTIAC IR-FIX F110W NSAMP=12, SAMP-SEQ=STEP50 2 DEF PATTERN 1 1 8 CUM ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 1 none 1 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 1 none 2 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 2 none 1 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 2 none 2 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 3 none 1 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 3 none 2 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 4 none 1 none 1 N/A CUM MM18423+5938 1 WFC3/IR MULTIAC IR-FIX F110W 4 none 2 none 1 N/A CUM 12480( 2) - 29-Jun-2011 15:52:43 - [ 6] Summary Form for Proposal 12480 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=12, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PCS MODE FINE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W ------------------------------------------------------------------------------------------------------------------------------------ Target Names MM18423+5938 ------------------------------------------------------------------------------------------------------------------------------------