Telecon Notes Oct. 17, 2018

Attendance: Amy Trangsrud, Tim Pearson, Marcel Schmittfull, Charles L., Al K., Nick B., Jim, Dan Green

Notes by: Karl Young

• Including any S4 Forecasts? (default = no)
• Including figure showing comprehensiveness of science?
• Update on status of report + action items
  • Reminder of Schedule: essentially final version to be distributed to ~15 external reviewers by Nov. 15.
  • subtopic: breadth is important for space missions. Are we missing any science deliverables (even if they are not in the STM)?

Including any S4 Forecasts? (default = no)

• SH (via Charles): default no. would be nice for reviewers to see, but complexity of coordinating with S4 and maybe LiteBIRD is unlikely to happen in next 30 days.
• AK: There is a section about complementary. SHould say something about how probe fits in.
• NB: My understanding was there is discussion of S4, but this would be additional detailed quantitative forecasts.
• AT: I understood that qualitative comparisons are in already, quantitative is what under discussion.
• NB: S4 is currently redoing forecasts for 2020 decadal (won't converge in < 30 days), so there isn't any way to do a quantitative comparison
• DG: agree, quantitative is very difficult. Could do a 'generic ground mission' at some noise level.
• CL: Need at least some comparisons to justify a $1 billion mission. For example need to discuss r. BICEP/KECK limits at 0.06, S$ aiming at r = 10^-3, etc. orders of magnitude are sufficient. What do people think?
  • AK: yes, makes sense.
  • NB: works for r, yes.
  • AT: yes, there are a lot of science goals. maintain the emphasis on a broad science case.
  • MS: are there other examples that are also clear/simple? besides r. Is PICO much better on other science goals?
  • DG: order of magnitude is good for r. qouting exact numbers for each science target may be difficult. can we be quantitative there as well.
  • TP: need to be quantitative at the level that is possible.
  • JB: r, order of magnitude is fine. A target at that level would be even better.
• CL: Comment – we don't demonstrate in the report that PICO gets to 10^-4. we can't yet. We need to discuss the work needed to enable that demonstration.
  • AK: that's a real danger. This is a common conservatism in CMB forecasting. Other fields tend to be more optimistic. My do ourselves a disservice by being to careful/cautious/pessimistic in forecasts and being compared to more optimistic forecasts.
    • CL: CMB is a mature field. 3 space missions, many generations on ground. Hope can't overwhelm reality. we know the problems better than newer fields.
    • CL: This report is oppurtunity to specify to NASA what work needs support. Tech + systematics + foregrounds + simulations . . . Need to stress all these areas in report.
    • AK: agree r = 10^-4 is challenging task. but don't need to get there with this report. This isn't a direct satellite proposal at that level. We just need a plausible path to 10^-4 not a bulletproof path.
      • CL: completely and exactly agree. This is not a mission proposal. So we can discuss the work needed to get to 10^-4 to encourage investment in that work.
      • JB: do we know what needs to be done? Can we be specific?
        • CL: partially. Need to separate foregrounds, currently working on full sky models. need to include variations in dust, synchrotron, etc. Also need simulations to include systematic effects in detail. currently 60x lower noise than Planck. Planck already systematics dominated, so PICO will need better systematic control.
        • JB: Emphasis on complex dust helps PICO.
    • CL/AK, this discussion can be done in a positive 'this work will be done' way rather than a negative 'foregrounds have not been separated, systematics not controlled' way.

Including figure showing comprehensiveness of science?

• from a SO talk by Colin H. originally from ESO. CL: is this useful? good figure?
• AK: nice figure. PIXIE had a similar range of science figure, but it didn't seem to impress anyone. May have given the impression of not enough focus.
• AT: Probe is larger so talking about a broader science goal is reasonable. Looks like an executive summary or science intro section type figure. Needs fewer words, should focus on broad science. Include in draft and see what feedback we get.
• MS: worth adding. good figure.
• Generally in favor. But needs some editing to have less text.

Update on status of report + action items

• NB and SH working on comments and revisions in Intro and Extra-galactic section. Colin also has been editing. Need a few more cuts to reionization and adding some CMB halo lensing text and clusters and legacy catalog text.
• NB/DG adding a few sentences on Neff and clusters to fundamental physics section.
  • DG: some exact organizing needs to be figured out, working with RF.
  • CL: Rafael will be back and do serious work this weekend.
  • NB will add a couple sentences on clusters and neutrinos in < 1 week timescale

• CL: there is a lot of detail on foreground sims. Thought this would be better in an appendix, rather than in the flow of text.
  • NB: similar to how CDT did? CL: yes. NB: sounds reasonable. Liked the CDT. and S4 will be doing a similar thing.
• subtopic: breadth is important for space missions. Are we missing any science deliverables (even if they are not in the STM)?
  • No immeadiate ideas.
  • CL send STM comment to SH
  • JB: large scale structure? Don't see it in STM.
    • NB: yes, that was removed. We couldn't come up with statements on what PICO would do specifically. and PICO doesn't have the resolution to compete with ground. The details of how PICO helps seemed too far inside the field, not interesting to larger audience.
    • JB: will keep thinking about, maybe can discuss offline. NB: sure. we're open to thoughts on how we can add this to STM. There is text in the report on this topic.
      • NB: mostly the resolution issue meant PICO does significantly worse. NB and JB will talk offline in next few days
  • CL: Note that there is lots of detail of some very specific science goals. We should have a somewhat uniform criteria for how detailed we go in each topic. Example is the galactic science is quite detailed.
    • CL: we've been in accretion phase. when reading report consider what level of detail should stay, how to make the whole more uniform and coherent.
  • JB: general question, if we do worse that S4 do we just not discuss that? Or do we still say PICO does XXXX.
• Reminder of Schedule: essentially final version to be distributed to ~15 external reviewers by Nov. 15.
  • CL: Amy, status of instrument section?
    • AT: Various chapters. Instrument is most mature. Management is least mature. Will send them in piece by piece. planning to send everything by 7-10 days.
  • CL: process for including?
    • TP: section will go out to review as word doc. Not converted to latex yet. Just glued to github for now. Will convert all to latex after Nov. 1. Focusing on cleaning up the material that is currently on github.