Title Circumnuclear Starburst Rings: From Gas to Stars Pi E. Schinnerer Time 80 hrs 1. Name of program and authors 1.5.2: Name -- Circumnuclear Starburst Rings: From Gas to Stars Authors: E. Schinnerer 2. Science goal: We will perform a high-resolution imaging (5-10pc) study of the molecular gas, including individual GMC complexes, in a sample of nearby (D ~ 17 Mpc) spiral galaxies containing circumnuclear starburst rings which are generally associated with large-scale stellar bars. These rings have typical diameters of about 1 kpc and are the sites of massive star clusters similar to those observed in merging systems. Comparison to high-resolution optical and NIR imaging data as well as radio continuum data will allow us to study the process of star formation from the gas phase via HII regions to 'fossil' star clusters. This comprehensive data set will allow us to access the process of star formation in an environment with short dynamical timescales. In addition, the gas kinematics and distribution will be compared to dynamical models for the gas flow in such circumnuclear rings. For a direct comparison to the models it is essential that the entire gas content is observed to test whether the assumption of continuity in the models is valid. This study has also direct consequences for possible feeding mechanisms of nuclear BH or star clusters. 3. Number of sources: 10 4. Coordinates: 4.1. Virgo cluster targets plus others 4.2. Moving target: no 4.3. Time critical: no 5. Spatial scales: 5.1. Angular resolution (arcsec): 0.05" 5.2. Range of spatial scales/FOV (arcsec): 0.05" to 15" 5.3. Required pointing accuracy: ~ 1" 6. Observational setup 6.1. Single dish total power data: required Observing modes for single dish total power: on-the-fly mapping 6.2. Stand-alone ACA: no 6.3. Cross-correlation of 7m ACA and 12m baseline-ALMA antennas: required 6.4. Subarrays of 12m baseline-ALMA antennas: no 7. Frequencies: 7.1. Receiver band: Band 6 -- 230 GHz in Configuration ABCD 7.2. Lines and Frequencies (GHz): CO(2-1) @ 230 GHz 7.3. Spectral resolution (km/s): 2-3 km/s 7.4. Bandwidth or spectral coverage (km/s or GHz): ~ (800 - 1000) km/s 8. Continuum flux density: 8.1. Typical value (Jy): < 0.5 mJy/beam at 230 GHz 8.2. Required continuum rms (Jy or K): 8.3. Dynamic range within image: 8.4. Calibration requirements: absolute ( n/a ) repeatability ( n/a ) relative ( n/a ) 9. Line intensity: 9.1. Typical value (K or Jy): <= 60 mJy/beam at 230 GHz 9.2. Required rms per channel (K or Jy): 0.6 mJy/beam 9.3. Spectral dynamic range: 5 - 100 9.4. Calibration requirements: absolute ( 5% ) repeatability ( 5% ) relative ( 1-3% ) 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): 1 track (+/- 1hr) at 230 x 10 sources x 4 configurations 12. Total integration time for program (hr): 80 hr 13. Comments on observing strategy : (optional) Tracing the gas flow in the centers of galaxies depends critically on measuring the distribution of the entire (molecular) gas. Thus short spacings are essential to probe diffuse extended material. ----------------------------------------------------------------------------- Revised version of drsp1_1.5.2.txt. The science goal has been up-dated and slightly modified thus some of the previous comments might not be relevant anymore. ************************************************************************* Comments: science goal.. surely the distance is 17 Mpc.. not kpc --> Corrected the science goal seems now to partially overlap with 1.5.1.. study of the gas flow feeding the back hole. However the emphasis is on the study of the formation of star clusters in starburst rings. This is definitely very interesting. --> Indeed, the emphasis of this project is on the onset, the continuation and possible determination of star formation in small rings around galactic nuclei. While the star formation might interact with the feeding of a (putative) black hole, it is not clear at all how and when in time, thus the science questions posed here are clearly distinct from 1.5.1. The number of sources proposed is 10. I don't understand why 10.. 1 could already be very interesting. Any number between 1 and 10 could be ok too. --> The geometry of starburst rings depends heavily on the shape of bar (strong, weak) as well as the gravitational potential of the bulge (early vs. late Hubble type). In addition, starburst rings have diameters ranging from a few 10pc to several 100pc and some galaxies host even two nuclear rings within their inner kiloparsec. Thus in order to be able to identify mechanisms for star formation that are similar in all types of starburst rings and to isolate the environmental effects a sample of 10 galaxies appears to be the bare minimum for some statistical analysis. estimated time is ok ************************************************************************* Previous comments: Review Jean Turner: Starburst rings are good targets, not well understood, and neither is SSC formation. Putting CO together with high resolution optical and near-IR imaging can provide useful circumstantial evidence for how star formation proceeds. Number of targets is somewhat arbitrary but about right; could reduce the time request to half and still have enough galaxies to discern patterns. Technical aspects. There will not be much power on the smallest angular scales, I don't think you will gain much in these galaxies below ~0.08-0.1" (1K). However, this is a multiconfiguration proposal, so that would perhaps mean one configuration's worth of data, and you never know, there could be hot spots. So this is okay. This project does not really need ACA or single dish since the focus is GMCs. 230 GHz is good for GMCs and for the primary beam, since the starburst rings are ~10-15" in size (1 kpc). Higher frequency CO lines may not show up due to excitation, and will have smaller primary beams. Integration time is reasonable.