! $Id: 5491,v 12.1 1995/03/07 19:10:39 pepsa Exp $ coverpage: title_1: YOUNG GALAXIES AND THE IONIZATION OF THE INTERGALACTIC MEDIUM sci_cat: GALAXIES & CLUSTERS sci_subcat: EVOLUTION/COSMOLOGY proposal_for: GO pi_fname: TIMOTHY pi_mi: M. pi_lname: HECKMAN pi_inst: JOHNS HOPKINS UNIVERSITY pi_country: USA hours_pri: 8.25 num_pri: 2 foc: Y off_fname: CHERYL-LEE off_lname: HOWARD off_title: ASST. DEAN FOR ADM. off_inst: JOHNS HOPKINS UNIVERSITY off_addr_1: 3400 N. CHARLES ST. off_city: BALTIMORE off_state: MD off_zip: 21218 off_country: USA off_phone: 410-516-8668 ! end of coverpage abstract: line_1: We propose slitless spectroscopic observations with the FOC of two luminous line_2: star-forming galaxies at z~0.4 to determine the amplitude of their intrinsic line_3: Lyman breaks. The opacity to ionizing UV photons of even the closest line_4: starbursts, not to mention the Milky Way, remains highly uncertain and yet line_5: bears directly on such issues as the ionization source for the Lyman-alpha line_6: forest and other QSO absorption-line systems, the reionization of the early line_7: universe, the strength of the local UV background radiation, and the physical line_8: state of gas in galactic gaseous halos. By obtaining sensitive, low-resolution line_9: spectra covering the redshifted Lyman limit breaks of two actively star-forming, line_10: narrow-emission-line galaxies, we can directly measure or set limits on the line_11: escaping ionizing UV light. We will extrapolate the results to higher line_12: redshifts in an effort to interpret galaxies at early epochs and to test the line_13: hypothesis that primeval galaxies ionized the IGM at z>3. HST observations are line_14: required for this project due to the starbursts' extreme faintness and the need line_15: for sensitivity near 1300A. With the refurbished PSF, we should also be able line_16: to resolve the galaxies spatially, which will help quantify the scales of line_17: patchiness of the UV absorption and emission. ! ! end of abstract general_form_proposers: lname: HECKMAN fname: TIMOTHY mi: M inst: 2380 country: USA esa: N ! lname: LEITHERER fname: CLAUS inst: 3470 country: USA esa: N ! lname: SMITH fname: LINDA inst: 8090 country: UNITED KINGDOM esa: Y ! lname: LOWENTHAL fname: JAMES mi: D. inst: 2380 country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We have selected two narrow-emission line galaxies satisfying the following line_2: criteria: line_3: (1) z>0.35 to shift the Lyman limit break well past geocoronal Ly-a; line_4: (2) u<20.5 and u-b<-0.5 to maximize the detectability of UV light; line_5: and (3) [O II] 3727A Rest Equivalent Width > 20A and FWHM < 300 line_6: km/s, indicative of copious star formation. line_8: We wish to obtain slitless spectra with the FOC operating in objective line_9: prism mode of each galaxy to measure the emergent flux below the Lyman line_10: limit. We require no more exposures than are necessitated by the line_11: spacecraft orbital parameters. line_13: We also require non-dispersed images of each galaxy to establish the line_14: wavelength zero-point of each spectrum, which must be obtained line_15: immediately following the images. For this purpose we have chosen the line_16: F342W filter, which will allow us to compare the morphologies of these line_17: z=0.4 starbursts with those at z=0 studied by Heckman with HST at the line_18: same rest wavelength, ~2500A. This filter also allows us to take line_19: advantage of the FOC's peak sensitivity. line_21: Galaxy z lambda(Lyman break) u u-b line_22: SGP1:10 0.426 1301A 20.14 -0.72 line_23: QNY1:32 0.445 1318 20.37 -0.69 ! question: 4 section: 1 line_1: HST is required for these observations because we need access to line_2: spectral regions just longward of geocoronal Lyman-alpha, but we also line_3: need high sensitivity for the detection of the low flux levels line_4: expected (F(lambda)~10e-16 erg/sec/cm^2/A at 1300A), so space-based line_5: observations are necessary but IUE is not a viable possibility. line_7: Furthermore, although our targets were originally discovered because they line_8: appeared unresolved in ground-based images, we expect HST to line_9: be capable of resolving morphological details on the scale of < 500 pc; line_10: at z=0.4, 1 arcsec corresponds to about 3.3 kpc (for H=100 km/s/Mpc). ! ! !end of general form text general_form_address: lname: HECKMAN fname: TIMOTHY mi: M. category: PI inst: 2380 addr_1: DEPARTMENT OF PHYSICS AND ASTRONOMY addr_2: JOHNS HOPKINS UNIVERSITY city: BALTIMORE state: MD zip: 21218 country: USA phone: 410-516-7369 telex: heckman@pha.jhu.edu ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: SGP1-10 descr_1: E,318 pos_1: PLATE-ID=025A, pos_2: RA=00H 58M 13.778S +/- 0.08S, pos_3: DEC=-28D 15' 57.12" +/-1" equinox: 2000 rv_or_z: Z = 0.426 fluxnum_1: 1 fluxval_1: U=20.14 +/- 0.5 fluxnum_2: 2 fluxval_2: U-B=-0.72 +/- 0.5 ! targnum: 2 name_1: QNY1-32 descr_1: E,318 pos_1: PLATE-ID=012G, pos_2: RA=12H 36M 36.649S +/- 0.07S, pos_3: DEC=-00D 37' 23.87" +/- 1.0" equinox: 2000 fluxnum_1: 1 fluxval_1: U=20.37 +/- 0.5 fluxnum_2: 2 fluxval_2: U-B=-0.69 +/-0.5 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 101.000 targname: SGP1-10 config: FOC/96 opmode: IMAGE aperture: 512X512 sp_element: F342W num_exp: 1 time_per_exp: 800S priority: 1 req_1: CYCLE 4; req_2: SEQ 101-102 NO GAP; req_3: DARK TIME; comment_1: UNDISPERSED IMAGE FOR WAVELENGTH comment_2: CALIBRATION OF EXPOSURE 102. ! linenum: 102.000 targname: SGP1-10 config: FOC/96 opmode: IMAGE aperture: 512X512 sp_element: PRISM1 wavelength: 1140-5660 num_exp: 1 time_per_exp: 9700S priority: 1 req_1: CYCLE 4; req_2: POS TARG +0.0,-4.5; req_3: DARK TIME; comment_1: SPECTRUM OF GALAXY comment_2: IMAGED IN EXPOSURE 101 ! linenum: 103.000 targname: QNY1-32 config: FOC/96 opmode: IMAGE aperture: 512X512 sp_element: F342W num_exp: 1 time_per_exp: 800S priority: 1 req_1: CYCLE 4; req_2: SEQ 103-104 NO GAP; req_3: DARK TIME; comment_1: UNDISPERSED IMAGE FOR WAVELENGTH comment_2: CALIBRATION OF EXPOSURE 104. ! linenum: 104.000 targname: QNY1-32 config: FOC/96 opmode: IMAGE aperture: 512X512 sp_element: PRISM1 wavelength: 1140-5660 num_exp: 1 time_per_exp: 9700S priority: 1 req_1: CYCLE 4; req_2: POS TARG +0.0,-4.5; req_3: DARK TIME; comment_1: SPECTRUM OF GALAXY comment_2: IMAGED IN EXPOSURE 103 ! ! end of exposure logsheet ! No scan data records found