Title A deep search for line-emitting galaxies using ALMA Pi A. Blain Time 160 hrs 1. Name of program and authors A deep search for line-emitting galaxies using ALMA Andrew Blain 2. One short paragraph with science goal(s) So far, no galaxies have been discovered directly by their CO line emission. Only unusual catagories of distant galaxies: the brightest QSOs and most luminous dust-enshrouded galaxies have been detected. The properties of typical field galaxies in CO lines at even moderate redshifts is not currently known. ALMA has the sensitivity to search for their CO emission very efficiently, especially at longer wavelengths, where the fractional bandwidth is greatest. The 140-GHz band is likely to be most sensitive ultimately, but Band-3 can be used straightaway. Band-3 combines a wide primary beam, a large fractional bandwidth, availablility in the worst of observing conditions, and access to CO lines that have a high probability of excitation (CO(5-4) and lower) out to z=5. To a 5-sigma depth of 0.3mJy, a 300-km/s line can probably be detected every hour in a staring observation. Other CO lines can then be targetted in detected objects to confirm redshifts, and the continuum emission should be easy to detect alongside at higher frequencies. The equivalent widths of CO lines can be used to provide a redshift estimate from a single CO line. 3. Number of sources (e.g., 1 deep field of 4'x4', 50 YSO's, 300 T Tauri stars with disks, ...; do NOT list individual sources or your "pet object", except in special cases like LMC, Cen A, HDFS) Scans of fields covered in other deep surveys. Parts of sky very adaptable. 4. Coordinates: 4.1. Rough RA and DEC (e.g., 30 sources in Taurus, 30 in Oph, 20 in Cha, 30 in Lupus) Indicate if there is significant clustering in a particular RA/DEC range (e.g., if objects in one particular RA range take 90% of the time) Could be widely spread. GOODS-S field at 02hr is an excellent candidate. Should target fields that have deep ALMA continuum imaging in preference to unobserved fields. 4.2. Moving target: yes/no (e.g. comet, planet, ...) No 4.3. Time critical: yes/no (e.g. SN, GRB, ...) No 4.4. Scheduling constraints: (optional) None 5. Spatial scales: 5.1. Angular resolution (arcsec): 1" Modest for line detection 5.2. Range of spatial scales/FOV (arcsec): (optional: indicate whether single-field, small mosaic, wide-field mosaic...) Single field 5.3. Required pointing accuracy: (arcsec) 1" 6. Observational setup 6.1. Single dish total power data: no/beneficial/required No Observing modes for single dish total power: (e.g., nutator switch; frequency switch; position switch; on-the-fly mapping; and combinations of the above) 6.2. Stand-alone ACA: no/beneficial/required No 6.3. Cross-correlation of 7m ACA and 12m baseline-ALMA antennas: no/beneficial/required No 6.4. Subarrays of 12m baseline-ALMA antennas: yes/no No 7. Frequencies: 7.1. Receiver band: Band 3, 4, 5, 6, 7, 8, or 9 Band 3 & 4: 4 tunings in each. If line detected then could cut bands to cover short - but likely not possible in real time. 7.2. Lines and Frequencies (GHz): (approximate; do _not_ go into detail of correlator set-up but indicate whether multi-line or single line; apply redshift correction yourself; for multi-line observations in a single band requiring different frequency settings, indicate e.g. "3 frequency settings in Band 7" without specifying each frequency (or give dummies: 340., 350., 360. GHz). For projects of high-z sources with a range of redshifts, specify, e.g., "6 frequency settings in Band 3". Apply redshift correction yourself.) Redshifted CO(4-3)/CO(5-4). 4 settings in B3 and B4. 7.3. Spectral resolution (km/s): 300 7.4. Bandwidth or spectral coverage (km/s or GHz): 8GHz 8. Continuum flux density: 8.1. Typical value (Jy): (take average value of set of objects) (optional: provide range of fluxes for set of objects) Of order 0.1mJy 8.2. Required continuum rms (Jy or K): Of order 0.02mJy 8.3. Dynamic range within image: (from 7.1 and 7.2, but also indicate whether, e.g., weak objects next to bright objects) Modest 8.4. Calibration requirements: absolute ( 1-3% / 5% / 10% / n/a ) repeatability ( 1-3% / 5% / 10% / n/a ) relative ( 1-3% / 5% / 10% / n/a ) 10% 9. Line intensity: 9.1. Typical value (K or Jy): (take average value of set of objects) (optional: provide range of values for set of objects) ~0.5 Jy km/s - in ~300 km/s line 9.2. Required rms per channel (K or Jy): 5-10-sigma, so 0.2mJy in 300 km/s 9.3. Spectral dynamic range: Modest 9.4. Calibration requirements: absolute ( 1-3% / 5% / 10% / n/a ) repeatability ( 1-3% / 5% / 10% / n/a ) relative ( 1-3% / 5% / 10% / n/a ) 10% 10. Polarization: yes/no (optional) No 10.1. Required Stokes parameters: 10.2. Total polarized flux density (Jy): 10.3. Required polarization rms and/or dynamic range: 10.4. Polarization fidelity: 10.5. Required calibration accuracy: 11. Integration time for each observing mode/receiver setting (hr): 360s per pointing, (~200 pointings at 90GHz to cover GOODS-S field) 12. Total integration time for program (hr): 200 pointings, 4 tunings, 2 bands, 8x200x360s = 57600s = 160 hours 13. Comments on observing strategy : (optional) (e.g. line surveys, Target of Opportunity, Sun, ...): Line surveys could be easily expanded/deepened. Expect about 2400 sources per square degree in a 24-GHz band at 5-sigma sensitivity of 0.3 Jy km/s, implies expect (150/3600)*2400 = 100 sources. The best strategy for line surveys is currently unclear, until the population of galaxies being probed is better quantified. Carrying out the survey at some of the settings, then reviewing and deciding whether to keep searching or follow up should bring down the total time by a factor of 2. The field will be contiguous, so calibrators and slewing will be quick and easy. Little retuning should be necessary until a substantial part of the field has been covered. Note that a z~1.2 redshift survey cannot be carried out any other way. -------------------------------------------------- Review v2.0: 1.1.7 Sensitivity calculation seems appropriate.