ALMA-IMF Core Working Group, July 2 2020

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

Attendees: Fred, Yohan, fab, Alex, Ben, Tapas, Nathalie, Patricio, Adam, Thomas, Hongli, Sasha
Not attending: Jeff, Gemma, Roberto

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


Agenda:

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

• Alex started building up a PPMAP temperature cube for W43-MM2&3. Alex presented his first results.
  

• ALMA data smoothed to 2”, all data reprojected onto 1.25” pixel size, beta=1.8, 7-70 K investigated
  

• First results (issues with edges of the W43-MM2 and MM3 combined image): 
  

Nh2: 3 main structures, up to 4 x 10^24 cm-2
    Mass-weighted temperature: from 20K (most of the image) to 35K (compact HII region), should be checked if there is a continuous rather than bimodal temperature distribution.

• Need to check the residuals (data - filtered model) of ALMA data could help check if small-scale variations are missing in the current model.
  

    Need to check the (1mm) offsets to be added to ALMA data to have proper SED fits at mm wavelengths
    PACS 70, 160 micron not zero-point corrected yet (use Planck and HIRES) but wouldn't it be easier to filter all images to 5’ beforehand? We are losing the absolute Nh2 values of filaments but it might not be so important after all...

• Reminder, 8 bands:
  
  • ALMA 12M-only cleanest images at 1mm (B6) and 3mm (B3)
    
  • Herschel 70, 160, 250, 500 micron images.
    
  • 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?
  

• Pending questions:
  
  • Are the combined 12M+7M data useful? or Do we use just 7M instead? 
    

• Add 0-point correction 
  
  • Adam asks: Why?  Would it not be better to filter out large scales from everything?  (the answer may still be no, but it’s worth doing some exploration)
    

For Herschel maps: SPIRE in the header, PACS offset to be given to Alex
For ATLASGAL: could Timea provide the ATLASGAL images with Planck offsets?

• 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
    
  • Need filtering scale of each image
    
  • If possible MJy/sr and the same projection (preferably RA---TAN, DEC--TAN
    

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

Roberto: I could provide the current FITS files. They are with the old cubes though. Will update at some point with new (better) cubes

1. Core extraction strategy

Here are the propositions from Fabien, Yohan and Fred, already discussed with Sasha and Sylvain. Feel free to comment and suggest improvements.

• For Fabien’s CMF paper
  

Use cleanest 12M-only images
with a detection step slightly different for evolved protoclusters
with non pb-corrected for detection and pb-corrected for measurements.

• detection in young & intermediate regions with 12M_B6_CLEANEST and 12M_B3_CLEANEST_NOPBCOR; detection in evolved regions with 12M_B6_CLEANEST_NOPBCOR only (no B3 used for detection due to the risk of free-free contamination)
  
• measurements in all cases: 12M_B6_CLEANEST and 12M_B3_CLEANEST 
  

Question from Sasha: why is it assumed that free-free contamination is important to avoid for detection, but not for measurements?
Fred: It will be an issue. As for now detailed CMFs will only be built for young (no HII region) and intermediate (localized compact HII region, where extracted sources are removed afterward). More detailed work involving H41a images will need to be done for evolved regions.

• For more detailed CMF papers
  

Use bsens and cleanest, 12M-only plus 12M+7M images
with a detection step different for evolved protoclusters
with cleanest used only for measurements
with non pb-corrected for detection and pb-corrected for measurements
with 12M+7M for tests
possibly with MnGSeg denoised maps.

• detection1: 
  

12M_B6_BSENS_NOPBCOR 
and, except for evolved protoclusters, 12M_B3_BSENS_NOPBCOR 

• measurements1: 
  

12M_B6_BSENS and 12M_B6_CLEANEST
12M_B3_BSENS and 12M_B3_CLEANEST

• To go deeper:
  

detection3: 
12M_B6_BSENS_denoised 
and, except for evolved protoclusters, 12M_B3_BSENS_denoised
measurements3: 
12M_B6_BSENS_PBCORR and 12M_B3_BSENS_PBCORR

• For test
  

detection2: 
12M+7M_B6_BSENS and, except for evolved protoclusters, 12M+7M_B3_BSENS
measurements2: 
12M+7M_B6_BSENS_PBCORR and 12M+7M_B3_BSENS_PBCORR

1. Improvement of the core extraction strategy of detailed CMF papers

• Tests at the detection step to enlarge the core sample and/or get better flux measurements:
  
  • the coherent component (using MnGSeg) of the B6_CLEANEST image could replace it. For W43-MM2&MM3, MnGSeg extraction allows a deeper extraction and the common sources with a normal extraction have a higher goodness quantity with denoised images. As a result, if we post-select the catalogs correctly, we can end up with ~20% more cores in the final catalog using MnGSeg technique. Note from Sasha: The 20% of cores may contain an unknown fraction of spurious sources. It must be first investigated, how many of those new sources may be accepted as real; for now it’s unknown. We may end up with more spurious sources, if the new sources remain not inspected carefully.
    

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

• Tests at the detection step: 
  
  • Who could investigate an evolved region to check if it provides a good estimate of the free-free component of 3mm and 1.3mm fluxes?
    

• Will “pure-continuum” images (with Jordan’s method or STATCONT) be available Nathalie?
  

1. Other points regarding core catalogs

• Post-treatment of core catalogs to better identify the columns to be used to get access to core’s characteristics. Yohan: I propose to develop a fully automated procedure to read your data, either if it is a getsf, GExt2D, dendogram, … catalog. To properly do this, I already have scripts to do that but I still need some human intervention to process a bit the catalog to create “universal column names”. After some discussions with Sasha and Sylvain, two options were promising:
  

1. write a code to edit a new catalog with the most important information in a very specific and standard format. Fabien already developed this kind of procedure for his CMF paper. Advantage: column ordering would be the same so reading your data should be very simple. Problem: not all parameters would be included so you will not be able to use one of them.
   
2. keep the actual structure and all the information but we need to edit a bit the catalog to create “universal column names” that will match the actual structure. Advantage: no matter the version, the nb of wavelength, the ordering, the scripts will search for specific column names and will adapt to it. Problem: still some adjustments to be done to get simple column names in GExt2D and based on the principle that these names won’t change from one version to another.
   

I (Yohan) then plan to develop a small code that will write this small header with universal column names to avoid human intervention. if you plan to use this user friendly procedure (python functions very detailed and simple to use), here are the different steps you will have to do:
            - obtain core catalogs by running getsf/GExt2D
            - run my small code to edit a header 
            - run my automatic reading procedure to get your data

• Pending questions for post-selection of cores: 
  

• What do we do about 3mm-only cores? (largest images, 3mm emissivity less well constrained, free-free emission, ??% more sources in W43-MM2&3)
  

• Pending questions for the publication of  core’s catalogs: 
  

• 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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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.