Title Dust in normal Lyman Break Galaxies Pi M. Sawicki Time 80 hrs 1. Name of program and authors Title: Dust in normal Lyman Break Galaxies. Author: Marcin Sawicki, marcin.sawicki@nrc.ca 2. One short paragraph with science goal(s) Star-formation rates and other properties of z~3 Lyman Break Galaxies (LBGs) remain only poorly constrained because of the poorly-understood starlight-absorbing interstellar dust that they contain. To properly understand the impact of dust, these objects must be observed in the rest-frame far-IR. Until now, however, normal LBGs were out of reach at these wavelengths and only one typical (but gravitationally lensed) LBG, MS1512-cB58, has been detected with SCUBA. We will use ALMA to obtain spatially unresolved continuum flux densities of 20 normal LBGs at 900 and 450um and use these data in combination with rest-frame optical, UV, and near-IR observations (in hand from HST and SIRTF) to map out the LBG spectral energy distributions over a wavelength range that spans dust both in absorption and in emission. These observations will allow us to constrain the properties of dust in emission such as its mass and temperature. 3. Number of sources: 20 4. Coordinates: 4.1. Rough RA and DEC all 20 in Southern GOODS field approximately at: R.A. = 03:32:27 Dec. = -27:48:31 4.2. Moving target: no 4.3. Time critical: no 5. Spatial scales: 5.1. Angular resolution (arcsec): ANY 5.2. Range of spatial scales/FOV (arcsec): individual point sources - one per field 5.3. Single dish total power data: no 5.4. ACA: no 5.5. Subarrays: no 6. Frequencies: 6.1. Receiver band: Bands 7 and 9 6.2. Lines and Frequencies (GHz): continuum 6.3. Spectral resolution (km/s): N/A 6.4. Bandwidth or spectral coverage (km/s or GHz): N/A 7. Continuum flux density: 7.1. Typical value (Jy): 0.1 mJy at 900um and 1 mJy at 450 um, based on SCUBA 850um flux density of the lensed LBG MS1512-cB58. Observations should continue until a reasonable detection is made (see #12 below) 7.2. Required continuum rms (Jy or K): 0.01 mJy in Band 7 0.1 mJy in Band 9 7.3. Dynamic range within image: 7 8. Line intensity: 8.1. Typical value (K or Jy): N/A 8.2. Required rms per channel (K or Jy): N/A 8.3. Spectral dynamic range: N/A 9. Polarization: no 9.1. Required Stokes N/A 9.2. Total polarized flux density (Jy) N/A 9.3. Required polarization rms and/or dynamic range N/A 9.4. Polarization fidelity N/A 10. Integration time for each observing mode/receiver setting (hr): Band 7 continuum: 20 x 3.25 hr Band 9 continuum: 20 x 1.75 hr 11. Total integration time for program (hr): 80 hrs 12. Comments on observing strategy (e.g. line surveys, Target of Opportunity, Sun, ...): (optional) Each target should be observed until a S/N=10 is reached, but for at least a total of 2 hrs and for not more than 7 hrs. ********************************************************************* Review Pierre Cox: This programme proposes to search the thermal dust continuum emission of 20 Lyman Break Galaxies at the highest frequencies (Bands 7 and 9). Clearly important science. It is not clear why a signal-to-noise ratio of 10 is requested for a detection experiment. Aiming for say s/n of 5-6 would reduce the observing time significantly. Comment EvD: keep programme as is, since it does not require much time overall; reduced S/N could be compensated by increased number of sources -------------------------------------------------- Review v2.0: 1.1.9 Achieving a sensitivity of 0.01 mJy rms at 900 um band is somewhat a time consuming business for a simple detection purpose, as suggested by previous reviewers; it will already require about 8 hours integration per source at 300 GHz (1000 um) band (more integration time for shorter wavelengths, such as 880 um). Cross-correlation between ACA and 12-m array antennas will be beneficial; especially for band 9 observations.