9885( 5) - 10/30/03 07:32 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9885 Version: 5 Check-in Date: 30-Oct-2003 07:31:03 1.Proposal Title: Probing the High Redshift Universe with Quasar Emission Lines ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Jack A. Baldwin Michigan State University CoI: Dr. Kirk T. Korista Western Michigan University N CoI: Dr. Gary J. Ferland University of Kentucky N ------------------------------------------------------------------------------------ 5. Abstract The quasar epoch is believed to be associated with the birth of the most massive galaxies, a time marked by rapid star formation and evolution. Quasar emission lines can reveal the chemical evolution and physical state of gas in the very center of these galaxies. Analysis of the observed line strengths, using tools that have recently become available, implies that the chemical composition of the emitting gas correlates with quasar luminosity in a way that is suggestive of the known galactic mass/luminosity/metallicity correlations. The emission lines can also reveal the form of the ionizing radiation field emitted by the central object. Understanding the evolution of the central powerhouse is important for black hole accretion physics and because its spectrum is likely to dominate the ionization of the IGM. There are many high-ionization permitted emission lines in the region below 1000A rest wavelength that can provide important new constraints on these measurements. Thus, there is a critical need for spectra over the full rest-wavelength range ~ 600A through the UV. Through a pilot Cycle 10 archival study, we have identified the QSO HE 1122-1648 as an optimal object for such a study. This QSO has a sufficiently high redshift (z = 2.4) so that we can see down to very short rest wavelengths (463A) in observed-wavelength regions where STIS has high sensitivity, and lies on a line of sight with an unusually low density of intervening Ly-alpha absorber clouds. A high-quality spectrum of this object will have implications for the ionization of the IGM and will leverage the unique UV capabilities of HST to complement the galaxy formation studies that NGST will do at higher redshift. ------------------------------------------------------------------------------------ 9885( 5) - 10/30/03 07:32 - [ 2] Observations Description ------------------------ We wish to take STIS spectra of the V=16.5 mag QSO HE1122-1648, in order to study the relatively weak emission lines at wavelengths shortward of the Ly- alpha emission line (Ly-alpha is at observed wavelength 2916A in this redshift z=2.400 object ). These lines should tell us much about the physics of the Broad Emission Line Region. We used a Cycle 10 archival project (HST-AR- 09189.01-A) to identify QSOs at z ~ 2 that are shown, by existing HST spectra, to have unusually small amounts of overlying Lya-forest absorption along the line of sight, and that do not have Lyman cutoffs. From this we have identified HE 1122-1648 as an optimal object for further study. It is at redshift z = 2.400, and has F_lambda(rest 800?) = 2.0x10^15 erg cm-2 s-1 ?-1 (L_lambda(rest 800?) = 1.1x10^43 erg s-1 ?-1 ). Our primary goal is to obtain high-quality 500 km/s resolution spectra over the full wavelength region below Ly-alpha, and to obtain accurate measurements of the profiles and strengths of the wide range of emission lines that appear in this spectral region. We specifically selected this object because of the very low density of Lya-forest absorbers along its line of sight, but we will remove the absorption lines that do exist by interpolating over them at much higher velocity resolution, using the STIS echelle gratings to obtain peak s:n ~ 6 per 7-10 km/s 2-pixel resolution element. The data will then be binned up to 30 km/s, producing s:n ~ 2-12, which will permit us to flag and interpolate over pixels containing sharp intervening absorption lines. The remaining pixels can then be smoothed to ~500 km/s resolution with s:n at least 20, but typically s:n ~ 30-40 over most of the spectrum. This is a good match for detailed studies of the broad emission line profiles. We used the STIS Exposure Time Calculator and the spectrum measured from the archival observations to find that we need a total of 13 orbits to obtain a high quality spectrum. Most of the time (11 orbits) will go into obtaining high-quality UV observations with grating E230M, using both prime tilt settings (1978? and 2707?) in order to get full wavelength coverage from 1574-3111?. We will also obtain one-orbit exposures in each of two settings with grating G430M (tilt settings 3165, 3423); this will get out to 3500?, beyond which we can use ground-based spectrographs to obtain further medium-resolution coverage as needed. We also wish to devote one orbit to obtaining short exposures with gratings G430L and G750L. This will produce simultaneous, well-calibrated spectrophotometry for the region to the red of Lya, so that in the future medium resolution ground-based spectra can easily be joined onto the HST observations The final result will be spectra giving full coverage over the rest wavelength range 463-3021?. For Visit 3 (the CCD observations) we used two different strategies to get several exposures per setting so that we can reject cosmic rays. For the two settings with grating G430M, where we will use one orbit per setting, we used a pattern of 3 steps along the slit, with CR_SPLIT = none. The idea was that this would do a better job of avoiding hot pixels than if we used CR_SPLIT = 3, but no pattern. However, for the short exposures with G430L and G750L, occasional hot pixels in the spectrum will not matter so much (we will just interpolate over them in the final spectrum), so we used no pattern, and CR_SPLIT = 2. Real Time Justification ----------------------- 9885( 5) - 10/30/03 07:32 - [ 3] Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9885( 5) - 10/30/03 07:32 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HE1122-1648 GALAXY, QSO RA=11H24M42.83S +/- 0.1", DEC=- J2000 V = 16.5 17D05'17.91" +/- 0.1", PLATE- ID=02MF Coordinate Source: GSC_SURVEY_PLATE 9885( 5) - 10/30/03 07:32 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.6 Coordinate_Frame POS-TARG Pattern_Orient 90.0 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 9885( 5) - 10/30/03 07:32 - [ 6] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE SCHED 30% On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HE1122-1648 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 1978 1 2383 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 3 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 1978 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 4 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 1978 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 5 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 1978 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 6 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 1978 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 none none none none 1 tbd 01 2 none none none none 1 tbd 01 3 none none none none 2 tbd 01 4 none none none none 3 tbd 01 5 none none none none 4 tbd 01 6 none none none none 5 tbd 9885( 5) - 10/30/03 07:32 - [ 7] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HE1122-1648 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 1978 1 2383 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 3 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 2707 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 4 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 2707 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 5 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 2707 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 6 HE1122-1648 STIS/N ACCUM 0.2X0.2 E230M 2707 1 2877 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 02 1 none none none none 1 tbd 02 2 none none none none 1 tbd 02 3 none none none none 2 tbd 02 4 none none none none 3 tbd 02 5 none none none none 4 tbd 02 6 none none none none 5 tbd 9885( 5) - 10/30/03 07:32 - [ 8] Visit: 03 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HE1122-1648 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HE1122-1648 STIS/C ACCUM 52X0.2E G430M 3423 CR-SPLIT=NO 1 746 S PATTERN 1 2 CD 1 ------------------------------------------------------------------------------------------------------------------------------------ 3 HE1122-1648 STIS/C ACCUM 52X0.2E G430M 3165 CR-SPLIT=NO 1 905 S PATTERN 1 3 CD 1 ------------------------------------------------------------------------------------------------------------------------------------ 4 HE1122-1648 STIS/C ACCUM 52X0.2E G430L 4300 CR-SPLIT=2 1 1000 S CD 1 ------------------------------------------------------------------------------------------------------------------------------------ 5 HE1122-1648 STIS/C ACCUM 52X0.2E G750L 7751 CR-SPLIT=2 1 1510 S CD 1 ------------------------------------------------------------------------------------------------------------------------------------ 6 CCDFLAT STIS/C ACCUM 52X0.1 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 03 1 none none none none 1 tbd 03 2 1 none none none 1 tbd 03 2 2 none none none 1 tbd 03 2 3 none none none 1 tbd 03 3 1 none none none 2 tbd 03 3 2 none none none 2 tbd 03 3 3 none none none 2 tbd 03 4 none none none 1 3 tbd 03 4 none none none 2 3 tbd 03 5 none none none 1 3 tbd 03 5 none none none 2 3 tbd 03 6 none none 1 none 3 tbd 03 6 none none 2 none 3 tbd 9885( 5) - 10/30/03 07:32 - [ 9] Summary Form for Proposal 9885 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 52X0.2E1 52X0.1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=NO CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE SCHED 30% PATTERN 1 2 PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E230M G430M G430L G750L ------------------------------------------------------------------------------------------------------------------------------------ Target Names HE1122-1648 CCDFLAT ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1978 2707 3423 3165 4300 7751 ------------------------------------------------------------------------------------------------------------------------------------