Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5491 Report Date: 18-Jul-95:17:31 Version: ********** Check-in Date: ********** 1.Proposal Title: YOUNG GALAXIES AND THE IONIZATION OF THE INTERGALACTIC MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO Sub Category EVOLUTION/COSMOLOGY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Timothy M. Heckman JOHNS HOPKINS UNIVERSITY USA ------------------------------------------------------------------------------------ 7. Abstract We propose slitless spectroscopic observations with the FOC of two luminous star- forming galaxies at z~0.4 to determine the amplitude of their intrinsic Lyman breaks. The opacity to ionizing UV photons of even the closest starbursts, not to mention the Milky Way, remains highly uncertain and yet bears directly on such issues as the ionization source for the Lyman-alpha forest and other QSO absorption- line systems, the reionization of the early universe, the strength of the local UV background radiation, and the physical state of gas in galactic gaseous halos. By obtaining sensitive, low-resolution spectra covering the redshifted Lyman limit breaks of two actively star-forming, narrow-emission-line galaxies, we can directly measure or set limits on the escaping ionizing UV light. We will extrapolate the results to higher redshifts in an effort to interpret galaxies at early epochs and to test the hypothesis that primeval galaxies ionized the IGM at z>3. HST observations are required for this project due to the starbursts' extreme faintness and the need for sensitivity near 1300A. With the refurbished PSF, we should also be able to resolve the galaxies spatially, which will help quantify the scales of patchiness of the UV absorption and emission. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 8.25 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5491 PI: Timothy M. Heckman Proposal Title: YOUNG GALAXIES AND THE IONIZATION OF THE INTERGALACTIC MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Timothy M Heckman 2380 USA Claus Leitherer 3470 USA Linda Smith 8090 UNITED KING X James D. Lowenthal 2380 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We have selected two narrow-emission line galaxies satisfying the following criteria: (1) z>0.35 to shift the Lyman limit break well past geocoronal Ly-a; (2) u<20.5 and u-b<-0.5 to maximize the detectability of UV light; and (3) [O II] 3727A Rest Equivalent Width > 20A and FWHM < 300 km/s, indicative of copious star formation. We wish to obtain slitless spectra with the FOC operating in objective prism mode of each galaxy to measure the emergent flux below the Lyman limit. We require no more exposures than are necessitated by the spacecraft orbital parameters. We also require non-dispersed images of each galaxy to establish the wavelength zero-point of each spectrum, which must be obtained immediately following the images. For this purpose we have chosen the F342W filter, which will allow us to compare the morphologies of these z=0.4 starbursts with those at z=0 studied by Heckman with HST at the same rest wavelength, ~2500A. This filter also allows us to take advantage of the FOC's peak sensitivity. Galaxy z lambda(Lyman break) u u-b SGP1:10 0.426 1301A 20.14 -0.72 QNY1:32 0.445 1318 20.37 -0.69 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. HST is required for these observations because we need access to spectral regions just longward of geocoronal Lyman-alpha, but we also need high sensitivity for the detection of the low flux levels expected (F(lambda)~10e-16 erg/sec/cm^2/A at 1300A), so space-based observations are necessary but IUE is not a viable possibility. Furthermore, although our targets were originally discovered because they appeared unresolved in ground-based images, we expect HST to be capable of resolving morphological details on the scale of < 500 pc; at z=0.4, 1 arcsec corresponds to about 3.3 kpc (for H=100 km/s/Mpc). ------------------------------------------------------------------------------------ 11. Address Information Name: TIMOTHY M. HECKMAN Category: PI Institution: 2380 Address: DEPARTMENT OF PHYSICS AND ASTRONOMY JOHNS HOPKINS UNIVERSITY City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: 410-516-7369 Telex (or e-mail): heckman@pha.jhu.edu ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5491 [ 3] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 SGP1-10 E,318 PLATE-ID=025A, 2000 Z = 1 U=20.14 +/- 0.5 RA=00H 58M 13.778S +/- 0.426 2 U-B=-0.72 +/- 0.5 0.08S, DEC=-28D 15' 57.12" +/-1" ------------------------------------------------------------------------------------------------------------------------------------ 2 QNY1-32 E,318 PLATE-ID=012G, 2000 1 U=20.37 +/- 0.5 RA=12H 36M 36.649S +/- 2 U-B=-0.69 +/-0.5 0.07S, DEC=-00D 37' 23.87" +/- 1.0" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5491 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 SGP1-10 FOC/96 IMAGE 512X512 F342W 1 800S 1 CYCLE 4 SEQ 101-102 NO GAP DARK TIME Comments: UNDISPERSED IMAGE FOR WAVELENGTH CALIBRATION OF EXPOSURE 102. ------------------------------------------------------------------------------------------------------------------------------------ 102 SGP1-10 FOC/96 IMAGE 512X512 PRISM1 1140- 1 9700S 1 CYCLE 4 5660 POS TARG +0.0,-4.5 DARK TIME Comments: SPECTRUM OF GALAXY IMAGED IN EXPOSURE 101 ------------------------------------------------------------------------------------------------------------------------------------ 103 QNY1-32 FOC/96 IMAGE 512X512 F342W 1 800S 1 CYCLE 4 SEQ 103-104 NO GAP DARK TIME Comments: UNDISPERSED IMAGE FOR WAVELENGTH CALIBRATION OF EXPOSURE 104. ------------------------------------------------------------------------------------------------------------------------------------ 104 QNY1-32 FOC/96 IMAGE 512X512 PRISM1 1140- 1 9700S 1 CYCLE 4 5660 POS TARG +0.0,-4.5 DARK TIME Comments: SPECTRUM OF GALAXY IMAGED IN EXPOSURE 103 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5491 [ 5] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 8.25 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category EVOLUTION/COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; SEQ 101-102 NO GAP; DARK TIME; POS TARG +0.0,-4.5; SEQ 103-104 NO GAP; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F342W PRISM1 ------------------------------------------------------------------------------------------------------------------------------------ Target Names SGP1-10 QNY1-32 ------------------------------------------------------------------------------------------------------------------------------------