ALMA-IMF Core Working Group, August 27 2020

Connection:
https://ufl.zoom.us/j/96368629056?pwd=c1JmbWN6Rll0ZkNjYzJZamtXZFdmUT09

Attendees: Fred, Alex, Sasha, Thomas, Adam, Nichol, Leo, HongLi
Not attending: Yohan, Jeff, Timea

For memory:
Minutes from our last telecon
Members and their main interests


Agenda:

1. News on the core extraction strategy of detailed CMF papers

Work by Yohan (analysis), Sasha (getsf), Jeff (MnGSeg) and Fabien (ALMA simulations), presented by Fred

• Tests using BSENS instead of CLEANEST:
  

On the 1mm/3mm images of W43-MM2MM3
→ 65% more sources (85→139)
→ common sources (85) should be better measured (from the goodness factor of getsf), fluxes only vary by 10% [TBC].
→ up to 6 [TBC with Nathalie] hot cores, for which the CLEANEST flux should be used

• Tests using MnGseg to remove the Gaussian noise:
  

On the 1mm/3mm images of W43-MM2MM3: 
→ 25% more sources (139→173)
→ common sources (139) should be better measured.
→ fluxes measured on MnGSeg vary by 20% for common sources to 40% for new sources [TBC]
Question: shall we trust more fluxes measured on the MnGSeg image? 
We were thinking to 
1. detect sources on MnGseg/BSENS/NoBeamCorrected and 
2. Measure on BSENS/BeamCorrected

On the synthetic images provided by Fabien (projected numerical simulations by Ntormousi+2019 processed by the ALMA simulator and MnGseg)
→ 20%-40% more sources (87→ 71 50sec, 133→190 240s), depending on the integration time/sensitivity of the input image.
→ common sources should be better measured. 
→ 3% (5/190 and 3/87) spurious sources only (versus <1% without MnGseg)
→ fluxes vary by 5-15% for common sources
To Do: Check on the truth table of synthetic sources if fluxes measured on the MnGSeg image are more trustable...

• Remaining tests on core extraction: 
  
  • For evolved regions with extended free-free emission @ 3mm and, to a smaller extent, at 1mm (News from Gemma?): 
    

Is using **only** 1.3mm for detection and filtering out cores with small 1.3mm/3mm fluxes enough to remove spurious cores/free-free blobs?

• Let us convince the referee that using the 7M+12M B6_BSENS image instead of 12M-only B6_BSENS is not a good idea (more noise, less sources, investigate the image difference)
  

• “Pure-continuum” images compared to BSENS and CLEANEST images
  

• Flux and CMF comparisons using different extraction tools (getsf, GExt2D and dendrogram). 
  

1. News on the core extraction of the global CMF paper

Work by Sasha (getsf), Sylvain (GExt2D), presented by Fabien

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

• News from Alex
  
  • Results of:
    
    1. using SPIRE (instead of SABOCA)
       
    2. High Pass Correcting (mean subtraction before comparison) of ALL bands
       
    3. Making 0 and negative flux pixels in the observations NaNs (and thus not fitting them with PPMAP)
       
  • Should use recovered flux, not internal RChiSquared values (Edges and cores have too much effect on total RChiSquared value) 
    
    1. Show ratio maps
       
  • How best to filter obs (see below)?
    
  • Next test - mask centre of brightest core - not designed to be a final model, but just to see if masking core creates better convergence for rest of the map   
    

• Pending questions and issues:
  
  • Are 12M+7M and/or 7M-only data data useful? 
    
  • Evaluation of the filtering scale of each image using MnGSeg
    
    

* Max recov. scale = ~0.6 x \lambda/Lmin         See equation nº6.1 (p53) in https://www.iram.fr/IRAMFR/ARC/documents/cycle1/alma-technical-handbook.pdf

• Free-free contamination level from H41a images.
  

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1. Temperature estimates

• 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. 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.