ALMA-IMF Core Working Group, June 25 2020

Connection:
https://zoom.us/j/92270792020?pwd=b1dndW96TkI4ZlNjcWIvbE5MS1lrQT09

Attendees: Fred, Alex, Roberto, Sylvain, Yohan, Sasha, fab, Nathalie, Lee, Thomas, Tapas, Ben, Adam, 
Not attending: Gemma

For memory:
Minutes from last week’s telecon
Members and their main interests


Agenda:

1. Core identification and first CMFs papers (WG led by Fabien)

• First-pass global CMFs, a point of clarification:
  

The goal of Fabien’s paper is to show the integrated CMF of all ALMA-IMF regions and possibly the 3 integrated CMFs for the young, intermediate, evolved regions imaged by ALMA-IMF. 

• Papers dedicated to CMFs of individual (or a couple of) regions:
  

It is mandatory to do a more detailed and more correct work on core catalogs and CMFs for the regions that have enough cores: 
Young: G327 (84 cores), G338 (63 cores), W43-MM2 and MM3 (63 cores), 
Intermediate: G12 (82 cores), W51E (159 cores)
Old: G10 (<100 cores), G333 (<183 cores), W51-IRS2 (<98 cores)
The topic of each paper is up to the responsible team since CMF alone might not be interesting enough. Some of us proposed to present MST and mass segregation analyzes, comparisons between ALMA-IMF regions. If you need other datasets (especially lines), please ask the DR team but these papers should rather be “continuum-focused” papers.
Here are the paper projects that will develop in the coming 6 months:

• Yohan et al.: W43-MM2&3, comparison with MM1 and discussion of mass segregation.
  
• Estrella et al.: W51-E, …
  
• Walker et al.: G327, …
  
• PhD student with Patricio and Fumitaka (Hideaki Takemura): G338, TBC. 
  
• Mélanie et al.: G12=W33, from October on.
  
• Thomas et al.: G010, G333, or W49,  from October on (evolved, will need more work).
  
• more?
  

1. Mass estimates (WG led by Alex & Fred)

• Alex started building up a PPMAP temperature cube for W43-MM2&3. Other fields will follow. Alex will present his first results - UPDATE: results delayed due to cluster scheduling.
  
• Here are decisions taken at our last (2020/06/18) telecon:
  
  • use fixed beta=1.8 for first run (variable in future)
    
  • degrade ALMA data to 2" (was 2.5’’ for W43-MM1)
    

    Fabien: could the PPMAP model have a 0.5’’ beam? 
Alex: Introducing 7M data could help but artefacts will most probably appear. And computing time will increase with the number of pixels...

• use just 12M-only for first run (maybe both 12M AND 7M images in the future)
  

• Issues to be solved:
  
  • Need to check equinox of ALMA regions (was at 0.1E-4) → Fred in her stitched data, Yohan in data produced by the DR pipeline
    
  • Checking how to add data taken at the same wavelength but with different beam and filtering scale → The HPCORR subroutine of PPMAP does high-pass correct the model before synthetic observations (with beam smoothing) are created and compared to observations
    
  • Need beam profiles for all observations (currently missing B3 beam)
    
  • If people are changing flux units and projection before sending to me, then please set everything to MJy/sr and the same projection (preferably RA---TAN, DEC--TAN, easiest to use Herschel images as a reference).
    

• Pending questions
  
  • Are the combined 12M+7M data useful? both at at 1mm and 3mm?
    

Fred: This was the map used for W43-MM1 (instead of 12M-only). It should be tried but I’m afraid that the large scales are very much attenuated and that you do not get more information than with the 12M-only image.

• Do we use just 7M instead? 
  

Alex: Maybe. Fourier combination for data taken at comparable bands. Using astropy/FFT, better than CASA/feathering. Could be dangerous to ask PPMAP to fit both small and large-scales  
Fred: What does comparable bands mean? Inaccuracy should be estimated.
Adam: another benchmark for fourier-space combination = feathering: https://github.com/radio-astro-tools/uvcombine/blob/master/uvcombine/uvcombine.py (it is exactly the same thing Alex described; it includes tools for converting units and regridding)
Lee: Test of clean on the MM2 field, with and without self-calibration. Strange behavior suggesting that small scales are missing… TBC later!

• Add 0-point correction 
  

For Herschel maps: SPIRE in the header, PACS offset to be given to Alex
For ATLASGAL: Timea could provide the ATLASGAL with Planck offset but current data could be more sensitive, TBC
For SABOCA, using Herschel + Planck is OK
ALMA 1mm and 3mm will most probably remain filtered (MUSTANG? BOLOCAM? TolTec? NIKA2?)

• Alex will explain us what are the necessary data sets:
  

8 bands

• ALMA 12M-only cleanest images at 1mm (B6) and 3mm (B3)
  
• Herschel 70, 160, 250, 500 micron images. The 350 micron image is only used to add a background to the SABOCA map.
  
• LABOCA 870 micron images
  
• SABOCA and/or Artemis 350 micron images
  

    Other useful data if they exist

• NOEMA 1mm-3mm images?
  
• MAMBO 1mm and/or BOLOCAM 1mm images?
  

• Free-free contamination level could be estimated from H41a images. Roberto?
  

1. Core extraction strategy

Here is just a summary of what we discussed last week. further comments? or suggestions?

• Our current agreement for young and intermediate protoclusters
  
  • use Band 6 (1mm) and Band 3 (3mm) 12M-only images for detection (for getsf: simultaneous detection without asking for 2 detections)
    
  • use Best Sensitivity = BSENS for detection and measurement (not used for hot cores): B6_BSENS and B3_BSENS
    
  • use Cleanest for measurement only: B6_CLEANEST and B3_CLEANEST
    

• Our current agreement for evolved protoclusters
  
  • only use the Band 6 (1mm) Best Sensitivity = BSENS 12M-only image for detection and measurement: B6_BSENS
    
  • use B3_BSENS, B3_CLEANEST, and  B6_CLEANEST 12M-only for measurement only
    

A proposition from Roberto last week made us think… 
Sasha and Sylvain agree that we should use the Non-pbcorr image for detection to avoid the effect of variable noise and work on a flattened image. We then could use the pbcorr image for measurement or, even simpler, multiply the measured fluxes in the Non-pbcorr image by the PrimaryBeam image itself.
The MnGSeg segmentation process produces a noise image (Gaussian part of the structure at the small scales) could give a good estimate of the noise in the map. Sylvain and Sasha could contact Jeff for that if it helps the extraction method.

Here are preliminary results of tests. We need volunteers to make others:

• TESTS AT THE DETECTION STEP. Other images could be used hoping to enlarge the core sample and/or get better flux measurements:
  
  • the coherent component (using MnGSeg) of the B6_CLEANEST image could replace the B6_CLEANEST. Results from Yohan on W43-MM2&3:
    

• the 7M+12M B6_BSENS image could replace the 12M-only B6_BSENS image. Who could compare catalogs? of which region?
  

• TESTS AT THE MEASUREMENT STEP. Other images could be used to help us post-select real cores and improve their flux measurement:
  
  • the proxy of the free-free emission map at 3 (and 1?) mm (using H41a images) could provide an estimate of the compact free-free emission measured toward cores. 
    

Does it help for evolved regions? or is it more efficient to measure 1mm/3mm flux ratios. Who could investigate an evolved region?
At minimum, these images will be use as masks for intermediate regions.

• in fine the “pure-continuum” image (with Jordan’s method or STATCONT) will provide a better estimate of the continuum emission. Deep cleaning of line cubes will take time… Who could help Nathalie?
  

• Others?
  

• Questions: 
  

• What do we do about 3mm-only cores? (largest images, 3mm emissivity less well constrained, free-free emission, ??% more sources in W43-MM2&3)
  
• What matching criteria do we use between bands? and between various extraction catalogs?
  
• Does it make sense to publish several catalogs? or median size and flux estimates? The Core extraction WG will investigate this issue but you could give your opinion here:
  

Note from Sasha: It is not the best idea to average measured quantities between the catalogs from different codes. This would decrease their accuracy, if one of the codes does measurements more accurately than the other. The question about measurement accuracy can only be answered by running the same benchmark by both codes and by
comparing the measured values with the truth table.



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• Who would like to start investigating thermometers like CH3OH, CH3CN, CH3CCH lines? Timea will start on G328. Someone else? Nathalie has begun with W43-MM1 and can go on with W43-MM2&3.
  

This information cannot be used for the 1st mass estimates we’ll make but we can expect publishing  more corrected core temperature and thus mass measurements in the future.

• Who could join Brian to help him get ready to ask for more ammonia data? Gemma? others?
  

Gemma: Yes, I can help with the ammonia data

•  Some ideas to constrain kappa? Someone interested? 1mm/3mm ratios are sometimes strange, maybe due to hot-core emission… To be investigated
  

• Fred could present the proxy she proposes for the protostellar luminosity, using the line contamination from COMs.
  

1. Foreseen papers on “Cores”

Survey papers:

• First-pass global CMF: (Fabien et al.). 
  
• Search for prestellar cores: 2 or 3 papers (Sylvain, Timea et al.; Patricio, Ben et al.; maybe Thomas et al. for W43)
  
  1.  Sylvain & Timea: The idea to detect/reject outflow in a systematic way (before a complete and detailed analysis of CO outflows) for all detected cores to produce a consortium validated list of pre-stellar core and with a clear focus on the one we can be sure they are indeed massive. This would also support follow-ups any other group in the consortium could be interested in. 
     
  2. Patricio & Ben: ...
     
  3. Thomas et al. (in prep.) has already done the careful analysis on W43-MM1 (cycle 2 data). Could be extended to W43-MM2...
     

Papers dedicated to individual (or a couple of) regions:

• Ionizing feedback in G333.6: Roberto et al.
  
• Case-study of G337.92
  
• Mass segregation in ??: HongLi
  
• Line survey in W51-E: Estrella et al.
  
• ?: Patricio
  
• others...
  

1. Cores fragmentation/multiplicity (Feasibility to be discussed)

• Isabelle and Benjamin statistically investigate the fragmentation cascade in Herschel and simulated images. The final goal is to link the multiplicity of cores and the multiplicity of YSOs (as IR detections) and correct CMFs.
  
• It requires emission maps sensitive to a large range of scales down to the protostellar binary regime (100 AU). The fragmentation should be investigated at >4 scales separated by a factor of 2, thus over at least a decade. 
  
• Questions: 
  
  • How to add short spacings to continuum ALMA data? Could we use NIKA2, LABOCA, Bolocam data? Shall we use PPMAP to combine them with Herschel data?
    
  • What high-resolution data could we use? Adam and Patricio have some.