Title Survey of massive molecular outflows with ACA and TP only Pi D. Shepherd Time 180 hrs DRSP 2.0, re-submittal of DRSP 1.1 project 2.2.7 1. Name: Survey of massive molecular outflows with ACA and TP only. Authors: D. Shepherd et al. 2. Science goal(s): Molecular outflows from massive and intermediate-mass young stars are generally complex and are the result of the combined energetics from several OB stars and lower mass YSOs in a relatively dense cluster. The global properties of massive flow complexes is important for understanding the star formation efficiency in massive star forming regions and being able to relate galactic and extra-galactic star formation regions. Our current understanding of massive outflows is often based on CO(J=1-0 or 2-1) images that may not cover the entire outflow and that assume optically thin emission - both of these constraints can dramatically underestimate the dynamics of the outflowing gas (often by more than a factor of 10). Thus, a survey of molecular outflows from intermediate to high-mass YSOs in 12CO(J=2-1), 13CO(J=2-1), & C18O(J=2-1) (along with several other shock and high-density tracers) using the ACA combined with total power observations would provide a uniform sample with accurate estimates of outflow, dense gas, and cluster properties. Continuum observations with at least 2GHz of bandwidth will also detect embedded high- and intermediate-mass stars in the cluster that may be contributing to the outflow dynamics. If the continuum emission can be distributed between 230 & 219 GHz will be used to estimate the millimeter SED of the driving source(s). The mosaics must also be sensitive to size scales up to about 60" in the outflow. Multi-scale reconstruction of the combined uv-data will be needed to generate the final mosaic images. High resolution is NOT required at this stage. Promising candidates will be identified during this program and high-resolution and high-sensitivity follow up studies will be proposed. ************** Note: A similar survey should be contemplated for lower mass outflows. The low-mass survey should be separate from this one because: 1) The lines chosen will likely be different (fewer high density tracers) and the spectral resolution will be different. 2) The spatial resolution should be lower (e.g. low-mass outflows are generally less than a kiloparsec away, lower resolution is required match the expected size scale in the flows). 3) The continuum sensitivity will need to be higher to detect dust emission around the less luminous sources. ************** 3. Number of sources: 20 - 10'x10' mosaics 4. Coordinates: 4.1. Rough RA and DEC: 20 sources distributed through out the galactic plane. There will likely be some clustering toward the inner quadrant of the galaxy. 4.2. Moving target: no 4.3. Time critical: no 4.4. Scheduling constraints: (optional): None 5. Spatial scales: 5.1. Angular resolution (arcsec): 10" 5.2. Range of spatial scales/FOV (arcsec): 10" to 60" FOV range from 5'-20', depends on distance & source structure. These will all be large-field mosaics. 5.3. Required pointing accuracy: (arcsec): 0.6" High pointing accuracy is required for accurate mosaic imaging with this band 6 primary beam. 0.6" should be achievable with reference pointing. 6. Observational setup 6.1. Single dish total power data: required Observing modes for single dish total power: Position switch in on-the-fly mapping mode 6.2. Stand-alone ACA: yes 6.3. Cross-correlation of 7m ACA and 12m baseline-ALMA antennas: no (*** NO ALMA ARRAY TIME REQUESTED ***) 6.4. Subarrays of 12m baseline-ALMA antennas: ? Not clear what this means. This project requires 2 subarrays: 1 for the ACA 7m array, and 1 for the ACA 12m TP antennas. 7. Frequencies: 7.1 Receiver Band: 6 7.2 Lines: Main lines of interest = CO isotopes (e.g. CO(J=2-1), 13CO(J=2-1), C18O(J=2-1)) Frequencies (GHz): 230, 220, 219 (lines listed are the main lines of interest, other will also be observed). 7.3 Spectral Resolution (km/s): 0.3 km/s 7.4 Spectral Coverage (km/s or GHz): 100-200 km/s per line 8. Continuum flux density: 8.1. Typical value (Jy): 0.5-10 mJy 8.2. Required continuum rms (Jy or K): 0.3 mJy (to detect primary driving source of the flow as well as any lower-mass YSOs in the cluster) 8.3. Dynamic range within image: > 20 There will be weak and bright, extended emission. 8.4. Calibration requirements: absolute ( 1-3% / 5% / 10% / n/a ) 5% repeatability ( 1-3% / 5% / 10% / n/a ) 5% relative ( 1-3% / 5% / 10% / n/a ) 5% This data will be VERY valuable for archive purposes (e.g. to combine with ALMA 12m array observations of the sources made at a later time). Thus, calibration accuracy should be adquate to ensure that this data is useful. 9. Line intensity: 9.1. Typical value (K or Jy): > 10 Jy at 12CO line peak 10-100 mJy in high velocity wings 9.2. Required rms per channel (K or Jy): 60 mJy/beam 9.3. Spectral dynamic range: > 10 9.4. Calibration requirements: absolute ( 1-3% / 5% / 10% / n/a ) 5% repeatability ( 1-3% / 5% / 10% / n/a ) 1-3% relative ( 1-3% / 5% / 10% / n/a ) 5% While absolute calibration and relative calibration between spectral lines in this band do not require extremely high accuracy, I think that the repeatability is another issue. This is a LARGE mosaic and if the line flux densities between different segments of the mosaic (taken on different days) and/or different observations of the same field ( ACA 7m & 12m dishes) have significantly different flux densities, this will compromise the accuracy of the final mosaic deconvolution. 10. Polarization: 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): 11.1 Time requested (for ACA 12-7m array) Assuming a multi-field mosaic, 50" primary beam for 7m dishes, 10'x10' mosaic, => 24x24beams = 576 fields (just less than Nyquist spaced). Estimate (ALMA sensitivity calculator doesn't work with 10" resolution), use calculator for 50 antennas, then multiply by 4 to get ACA time estimate: 60 mJy/beam RMS in each field => 10s integration on each field (0.3 km/s resolution) => 1.6hrs x 4 = 6.4hrs for one source Because fields will overlap, we will gain roughly a root 2 increase in sensitivity over the mosaic region. Integration time = 6.4/sqrt(2) hrs = 4.5 hrs times 20 sources = 90 hrs total for the survey. NOTE: this is an average time, assuming all flows mapped are 10'x10', actual time estimate may differ depending on size of actual outflow fields. 11.2 Time requested for ACA 12m total power dishes: Same as above, thus, 4.5 hr/source x 20 sources = 90 hours However, if the TP mosaic must be larger than the interferometric array (e.g. to get out of the galactic plane) then this time could increase by a factor of 4. 12. Total integration time for program (hr): * 90 hours for the ACA 7m array * 90 hours for the ACA 12m TP antennas 13. Comments on observing strategy : (optional) This project may have to obtain a larger mosaic in Total Power than the field needed to be covered by the interferometer for some sources. Actual size of the TP mosaic is uncertain. -------------------------------------------------- Review v2.0: 2.2.7 Shepherd Survey of massive molecular outflows In this, and all other projects, there seems to be an open question as to how much time is needed for the ACA component. The basic assumption seems to be 4 times the ALMA array times but I am not sure if this is well justified or not. A question I cannot answer.