Attendance: Amy, Nick B., Marcel S., Raphael F., Alex vE, Colin H., Dan G.

Notes by: Karl

• Report Mechanics
  • Current version posted on main wiki
  • Public repository: alive and kicking. Solution for updates found.
  • Science section is updated frequently. Engineering section of Nov. 1 is available. Updated engineering section will become public (again) on Dec. 20. No more closures.
  • Dec. 20 deadline for input of new material
• Report
  • Currently ~120 authors/endorsers (are institutions important?)
  • Executive Committee Listing
  • Reviewer comments - any questions?
  • This past week: progress on Legacy and Galactic
  • Executive summary:
    • Strauss - include *how* we get the science in the ES? pro - more concrete; con - need to introduce new terms, and ES becomes verbose and voluminous.
    • Bennett + Bock comments

Concerning the Executive Summary, I think that it is too detailed and is missing some really big picture motivation and description - especially for those not into CMB details.

I think you need to get across that there is a lot that we have learned about cosmology - largely from the CMB - but much that we still do not understand (dark matter, dark energy, inflation, etc.). There are now growing tensions between cosmology data sets. As our only probe of the early universe, future precision studies are essential for all of these problems, as well as for new questions that will arise in the intervening years.

You give lots of justifications for PICO, but the number of justifications will not carry the day as well as one or two really compelling stories - told in the most general terms: what's dark energy? what's dark matter? how did the universe begin? is GR right? (These are clearly understood to be important questions and I doubt that any exoplanet mission, for example, will answer them. That's why PICO is needed.)

Similarly, I think that your case for space in terms of multipole moments is too detailed and debatable. Instead, I think you should appeal to the generic advantages of a well-designed space mission in obtaining conditions that the ground can never match: (no atmosphere/weather, precision full sky coverage linking a wide range of angular scales, thermal stability, solar shielding, low magnetic fields, no ground pick-up, etc.).

Hi Shaul,

The audience is the decadal so I think one should be a bit broader than one would with a mission proposal template. Here are thoughts:

1) For why space, surely you want to highlight getting the complete B-mode spectrum, accessing both the reionization and recombination bumps. That's stronger than 'multiple patches' that one can do from the ground.

2) All-sky multi-frequency polarization data from Planck sets the stage for precision foreground control. We are building on this information that was not available in 2010. I think Raphael was saying the 'worst-case' foreground model now has decorrelation at limits from Planck, but could become better? If I got that right it would be a useful selling point.

I think you can make the points about technology and maturity with more favorable spin. E.g.

3) We are building on the legacy of Planck, which demonstrated multi-frequency detectors operating near background limits and accessing large angular scales. The cooling system leverages Planck's accomplishment of stable 100 mK operation. The main technology advance needed are large arrays of detectors operate near Planck's level of demonstrated performance. Significant advances have been made in the last decade with arrays and there are multiple approaches that can meet PICO's requirements.

4) Planck has shown methods for systematic error control especially on large spatial scales. Ground-based experiments have now demonstrated systematics control to < 50 nK deg-2 on degree scales, close to PICO's target sensitivity. We are building on these as well.

5) One might consider a figure to summarize the above flow of technology and systematics that will help make it stick in reader's minds.

The “points remaining necessary steps forward” section seems problematic. Technology adjustments are ok but I don't think we can ever make a foreground or systematics demonstration that is fully representative, so I would not offer them up as being necessary.

I like the idea of recommendations for endorsement, especially technology development and demonstrations. I'm not quite sure how to play the mission recommendation. Technically one would only have to ask for the probe mission class, but the inflation probe is a special case in that it was a recommended mission in 2010 and I would hate to give that up since it conveys some advantage in nasa support that would not be available as one of many potential probes.

Jamie

Report Mechanics

• All: no ?s.

Report

• Currently ~120 authors/endorsers (are institutions important?)
• Executive Committee Listing
  • SH: Current list is names from 2017 proposal. Current members of the EC telecon are acting as EC, but not currently in list. My plan is to list all people who joined EC telecon as EC members. Thoughts?
  • All: no response, so we'll take to mean this is fine.
  • SH: will amend EC list to be all those who have been on EC telecons
  • AT: Some other probes do list affiliations, but they have fewer authors. Don't see a need for affiliations.
  • RF: are we advertising for endorsers?
  • SH: have sent 1 (will send 2nd) emails
  • RF: is there a broader list we should send to? SH: How to find this people?
    • RF: I can send to additional people I know, mostly theorists, and ask them to forward. Names like Linde, …
    • SH: I think more endorsers is good. Should reach as many people as possible.
  • RF: Is there any downside to more endorsers?
  • AT: Other JPL reports are not including endorsers. But the number of people involved/interested in PICO is a strength we should flaunt.
  • SH: Since these go to the decadal the most sensible way to show community support is to have many endorsers. Then don't need some additional document of support later.
  • SH: Support outside of CMB community would be good. Anyone know names in adjacent fields? Particle phys?
    • DG: Will think of some names. Not quite sure where the balance is in terms of how connected people should be.
      • SH: for now 'The more the merrier'.
      • AT: yeah, by adding names to 'endorsers' hopefully we persuade people of our support and persuade more people to read and advertise PICO.
  • RF: can also send to email to workshop list.
  • DG: What is the mechanism?
    • SH: Link to form on main wiki page here or email name to Shaul
  • SH: will talk to Laura/Dave about Galactic science names
• Reviewer comments - any questions?
  • RF: From Martin some comments that affect overall structure. SH: yes, planning to follow-up on those shortly.
    • RF: I can move things, but we want to coordinate. (fnl, collecting all areas of a given science into their own section)
    • SH: You can move fnl around now. But check before moving other sections.
    • SH: I agree with Martin's (and others) comments to move things around to consolidate science areas.
    • SH: Opinions on method? SH move or section leaders move text? ALL: no comment. SH to rearrange science on 1 week timescale.
  • SH: Complementarity section. Did have 2 sections. 1. somewhat repetitive restating of complementarity with other surveys for various sciences. 2. general complementarity with ground. Should these be split? With 1 only being in science goal sections.
    • SH: an outstanding question is if there is anything in (1) that isn't somewhere else.
    • All: no objections.
  • SH: Exec summary and introduction may be too repetitive. Haven't made final decision, but may eliminate introduction. Each section has ~ 1 paragraph intro. Exec summary acts as overall intro to the report.
• This past week: progress on Legacy and Galactic science
  • SH: seem to be some tension between SO, S4, and PICO forecasts. Gianfranco doesn't understand how SO/S4 predict so many point sources. They have few mJy detection limit, on paper. SPT had the same limit (on paper), but never did better than ~20 mJy. Unclear why SO/S4 should do better. This problem is confusion driven. Working on sorting this out. Differences are currently at the order of magnitude level.
• Executive summary - see Strauss, Bennet, Bock comments above
  • SH: Strauss prefers us to explicitly say “limits on r from B modes”, “limits on neutrinos from lensing”, . . . All science limits with techniques in exec summary. Problem is then you need to add more explanations about what B modes are, what other techniques are. Could be buried in detail.
  • RF: Those techniques would be nice, but only if concise enough. Being buried in details makes it no longer a summary. And Bennet's comments are the opposite, saying the summary is too detailed.
  • SH: Currently leaving techniques and science details and new terminology out of exec summ.
  • SH: Bennet's comments; they are very general. But we're trying to make concrete claims through the STM. Not clear how to be as general as Bennet suggests and remain quantitative/concrete. Advice/ideas with specific text that capture quantitative and broad questions would be very welcome.
  • SH: Jamie comments; generally more specific. But he suggests less discussion of foregrounds and systematics in 'necessary next steps'. Charles would say the opposite. Can seem like we're not ready for a mission.
    • RF: Is clearly a fine line. It is true more work is needed. But maybe not everything done on full sky at high resolution. But one goal is getting decadal support for foregrounds and simulations. That is still worthwhile. But don't want to say we are very far from simulations that are critical for flying PICO. We may need more sims, but not every detail with all physics on the full sky needs to be simulated before PICO is ready to fly. Details on small patches are likely sufficient for most things.
    • SH: Need to capture the detail of what sims are realistic and what we do actually need. Don't need every last detail.
    • SH: Jamie's last paragraph. Endorsing idea of tech demonstration recommendation to decadal. Could ask for just Probe class or for inflation probe specifically (was recommended in 2010). The 2nd may carry some additional advantage by maintaining a special slot.
      • AT: There is discussion around bringing Probe leads together to advocate for a probe line. That benefits PICO. But the PICO report advocating for PICO makes the most sense.
      • SH: Jeff Booth (AT's boss) suggested white paper advocating probe line. I support if the paper is 'probe class is recommended' not 'probe class is recommend but don't choose a mission'. We shouldn't tell the decadal not to support PICO specifically.