ALMA-IMF Core Working Group, June 18 2020

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

Attendees: Fred, Fabien, Alex, Yohan, Sasha, Adam, Gemma, Sylvain, Ben, Nathalie, Manuel, Hongli, Amy, Tapas, Mélanie, Antoine, Estrella, Patricio, Lee, Roberto
Not attending: Thomas

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: Core extraction process, first core catalog release, all fields (Fabien et al.). Have a look at his talk at our 2020 consortium meeting. Fabien showed the evolutionary trend observed for CMFs through time.
  

Many of us have concerns on publishing the CMF of evolved regions with constant temperature assumptions. We will see in the process of building this 1st paper if it is worth it. Make simulations with T variations to try to retrieve the Salpeter slope.
Adam: Tests for W51 could be done using ammonia temperatures…
Fred: 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. It is mandatory to do a more detailed and more correct work on CMF for the regions that have enough cores. The topic of each paper is up to the responsible team since CMF alone might not be very interesting. Some of us proposed to present MST and mass segregation analyses, comparison between ALMA-IMF regions. If you need other datasets, please ask the DR team but these papers should rather be “continuum-focused” papers.

• Papers dedicated to CMFs of individual (or a couple of) regions:
  
  • CMF in W43-MM2&3 (young and intermediate): Yohan et al. Have a look at his talk at our 2020 consortium meeting.
    
  • CMF in G12=W33 (intermediate, 82 cores): Antoine with Mélanie starting her PhD in October.
    
  • CMF in evolved regions? (e.g. G010, G333, W49 from Roberto's project): Thomas starting his IRyA postdoc in October.
    
  • G327 and G338 are the obvious regions to study CMFs (84 and 63 cores in the first extraction, larger or equal than in MM2&3 - 63 cores) since they are young/easier to analyze. 
    

A PhD student working with Patricio and Fumitaka could start working on the core catalog of the G338 region. 
Walker is interested to work on the CMF of G327. 

• W51-E (159 cores) is the obvious intermediate region that should be studied. 
  

Gemma will work with Estrella (+Manuel and Adam) on the CMF of the W51-E region.

• Yohan presents his Python script to investigate and compare cores’ catalogs.
  

Roberto: Regarding all those spurious sources in the periphery of the FOV, an easy way of not having them would be to run the identification in the image previous to PB correction. I do it like that for dendrograms. I thought the other identification algorithms do not need this because they flatten and subtract the background, but it looks like this approach could be useful there too. Of course, after the core extraction the fluxes and uncertainties would need to be scaled by the PB response at their position.
Fred: I’m not sure this will help since it is more an edge effect than a noise effect. Sasha could potentially improve on that.

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

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

• Alex will soon start building up a PPMAP temperature cube for W43-MM2&3. Other fields will follow. Your field priorities: ...
  

Alex will explain us what are the necessary data sets:

• ALMA 12M-only cleanest images at 1mm and 3mm
  
• Herschel 5-band images
  
• LABOCA 870 micron images
  
• SABOCA and/or Artemis 350 micron images
  

    Other useful data

• ALMA 7M-only images? at 1mm and 3mm?
  
• NOEMA 1mm-3mm images?
  
• MAMBO 1mm and/or BOLOUCLCAM 1mm images?
  
• (a quick note, if they are of good quality, the combined 12M/7M images can be used by PPMAP. Need to discuss though)
  

    From 2020/06/18 telecon
    Decided to use fixed 1.8 beta for first run (variable in future?)
    Decided to use just 12m for first run (maybe 12m AND 7m bands separate for future)
    Need to check equinox of ALMA regions (was at 0.1E-4)
   

Before running W43 MM2/3 for final model:
* Need to decided following:
- Do we degrade 12m to 2"? Fred: Yes to 2.5’’
- Do we use combined 12m and 7m? Fred: In a second run yes.
- Do we use just 7m instead? Fred: To be tested...

Need beam profiles for all observations (currently missing B3 beam)

To run other regions:
Need observations from:
Herschel (all 5 bands)
SABOCA/LABOCA (or ArTeMiS instead of SABOCA)
ALMA 12 B6 and B3 (1.3mm and 3mm)*

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).

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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
    

Here are prelimnary 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 G338. 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?
  

•  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. Tools/data to be shared among the team

• Yohan’s Python script to investigate and compare cores’ catalogs
  
• LABOCA, SABOCA and Artemis 350 micron data for most regions
  
• Other data
  
• …
  

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.