The EPIC Concept for the Inflation Probe. Shaul Hanany (Minnesota), Adrian Lee (Berkeley), and Brian Keating (UCSD)

Transcription

1 The EPIC Concept for the Inflation Probe Shaul Hanany (Minnesota), Adrian Lee (Berkeley), and Brian Keating (UCSD)

2 NASA Mission Concept Studies, 2004 CMBPol (Gary Hinshaw, Goddard) NASA Mission Concept Study, 2008 Two Example Missions EPIC (Experimental Probe of Inflationary Cosmology, Jamie Bock, JPL) (Astro-ph/ ) EPIC (Jamie Bock, JPL) EPIC (Einstein Polarization Interferometer for Cosmology, Peter Timbie, Wisconsin) Coherent Receiver Concept (Mike Seifert, JPL) BEPAC Reviews Concept Studies PPPDT (~8/2007) leads CMB community to a unified response to NASA Solicitation

3 Title Here Experimental Probe of Inflationary Cosmology (EPIC) Jamie Bock JPL / Caltech (Astro-ph/ ) JPL Peter Day Clive Dickenson Darren Dowell Mark Dragovan Todd Gaier Krzysztof Gorski Warren Holmes Jeff Jewell Bob Kinsey Charles Lawrence Rick LeDuc Erik Leitch Steven Levin Mark Lysek Sara MacLellan Hien Nguyen Ron Ross Celeste Satter Mike Seiffert Hemali Vyas Brett Williams Caltech/IPAC Charles Beichman Sunil Golwala Marc Kamionkowski Andrew Lange Tim Pearson Anthony Readhead Jonas Zmuidzinas UC Berkeley/LBNL Adrian Lee Carl Heiles Bill Holzapfel Paul Richards Helmut Spieler Huan Tran Martin White Cardiff Walter Gear Carnegie Mellon Jeff Peterson The EPIC Consortium U Chicago John Carlstrom Clem Pryke U Colorado Jason Glenn UC Davis Lloyd Knox Dartmouth Robert Caldwell Fermilab Scott Dodelson IAP Ken Ganga Eric Hivon IAS Jean-Loup Puget Nicolas Ponthieu UC Irvine Alex Amblard Asantha Cooray Manoj Kaplinghat U Minnesota Shaul Hanany Michael Milligan Tomotake Matsumura NIST Kent Irwin UC San Diego Brian Keating Tom Renbarger Stanford Sarah Church Swales Aerospace Dustin Crumb TC Technology Terry Cafferty USC Aluizio Prata

4 Science Drivers Science Objective Measurement Criteria Instrument Criteria E PI C C O M P R E H E N SI V E E PI C L C Inflationary Gravity Waves Reionization Cosm. Parameters Neutrino mass, dark energy, map lensing shear Galactic magnetic fields Detect BB to r=0.01 after removal of foregrounds Positively detect both =5, =100 peaks EE to cosmic variance limit BB to cosmic variance limit W p -1/2 < 6 μk arcmin* GHz bands* Control systematics to negligible levels All sky coverage Resolution < 1 degree* Same as above + Moderate angular resolution (~5 ) Dust + Synchrotron polarization * Recommended by Weiss Committee

5 Design Approach EPIC is a Scan-Imaging Polarimeter Scan Modulated Polarimeters Simple technique, strong established history (maxipol, boomerang, bicep, quad) {EBEX, Planck-HFI, Clover, Polarbear, } Background Limited Sensitivity in a Single Technology GHz (or more) with bolometers High Sensitivity ~x10 better than Planck Requires large focal plane arrays High throughput optical designs Control of Systematics Goal: raw effects are x10 lower than statistical noise Requirement: characterize effects such as to remove below r=0.01

6 EPIC = Study of Two Implementations EPIC Low Cost (LC) EPIC Comprehensive Science (CS) ~3.5 m Delta II Mass 1.3 tons L2 orbit Atlas V Mass 3.5 tons L2 orbit LC CS 6 x 30 cm Telescopes Single 2.8 meter telescope Frequencies GHz GHz Resolution 0.9 at 90 GHz 4.6 at 100 GHz ~16 m Detectors 2366 Bolometers 1520 Bolometers Lifetime 2 years 4 years Cost $660M No assessment done

7 EPIC - LC EPIC Low-Cost Mission Architecture Six 30 cm Telescopes at 2 K 100 K 155 K 40 K 450 Liquid Helium 0.1 K bolometers NET = 1.2 μk sec Weight -1 = 2.5 μk arcmin ΔT pix =16 nk 2 noise margin 295 K 8 m Half-Wave Plate (2 K) Telescop e Freq [GHz] θ FWHM [arcmin] N bol [#] δt pix [nk] e 1 30/40 155/116 8/ /300 23/16 576/ cm Polyethylene Lenses (2 K) Focal Plane Bolometer Array

8 Passively Cooled Mirrors 293 K Receiver & Lenses 85 K 155 K EPIC - CS 2.8 m 0.1 K bolometers NET = 1.8 μk sec Weight -1 = 2.8 μk arcmin ΔT pix =16 nk 2 noise margin 20 m Freq [GHz] θ FWHM N bol [#] δt pix [nk] [arcmin]

9 Comparison of Raw Sensitivity 70 GHz; 65% of sky WMAP 8 year; / =0.3 Planck 1.2 year; / =0.3 EPIC-LC 2 year; / =0.3 EPIC-CS 4 year; / =0.3 No foreground subtraction; No systematic uncertainties

10 EPIC Bolometer Sensitivity already Achieved Two EBEX Wafers (~1500 TES Bolometers ) EPIC Goal Detector Sensitivity Courtesy of Jonas Zmuidzinas

11 Two EBEX Wafers (~1500 TES Bolometers ) BICEP-II (512 TEPS Bolometers) Back: ACT one of 3 32x32 arrays SCUBA2 Focal Plane (10,000 TES Bolometers) One SPT Wafer (~1000 TES Bolometers)

12 Foreground EPIC Redundant Low-Cost Removal & Mission Uniform Architecture for Scan EPIC-LC Coverage Only dust + synchrotron space subtraction (Amblard et al. 2007) Dust + synch correlations from simulations Polarization amplitude = 5% of dust intensity (model 8), or from synch Polarization orientation = synchrotron traces B field Can reach r=0.003 (99%, binned 2< <100)

13 Systematic Error Study

14 EPIC-LC Systematic Error Mitigation Systematic Description Goal Mitigation Main beam Effects Instrumental Polarization Δ Beam Size FWHM E FWHM H <4 x 10-5 Δ gain G HWP in front; E G H <10-4 Refractor; Δ Beam Offset Point E Point H <0.14 Scan crossings Δ Ellipticity e E e H <6 x 10-6 Sat. Pointing Q, U Offset <0.12 Gyro + tracker Main beam Effects Cross Polarization Δ Rotation E, H not orthogonal <4 HWP in front; Pixel rotation E,H rotated <2.4 Measure and Subtract Opt. Cross Pol Birefringence <10-4 Sidelobes Scan Synchronous Signals Diffraction, Scattering Refractor + Baffle Thermal drift Sun viewing angle <1 nk Thermal design Magnetic Pickup Achieved TES, SQUID susceptibility Shielding Requires space Tested by sub-orbital experiments

15 EPIC-LC Systematic Error Mitigation Systematic Description Goal Mitigation 40 K Baffle Thermal Stability 5 mk/ Hz; Varying power from 5 μk s/s 2 K Optics thermal emission 500 μk/ Hz; 0.1 K Focal Plane Thermal signal induced in detectors 1/f Noise Detector + readout gain drift Passband Mismatch Gain Error Variation in Filters Relative responsivity uncertainty Achieved Requires space Tested by sub-orbital experiments Other 1 μk s/s 200 nk/ Hz; 0.5 nk s/s Temperature Control Hz Demonstrate, or faster scan, or modulate HWP Δν c /ν c <10-4 Δν c /ν c <10-4 Measure to required level Orbit-modulated dipole

16 Optical Axis Orbit Moon 55 Spin Axis (~1 rpm) 45 Sun Sun-Spacecraft Axis (~0.3 rph) Earth SE L2 Why Space? - All-Sky Coverage - High Sensitivity - Systematic Error Control - Broad Frequency Coverage

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18 Scan Strategy Optical Axis 55 Spin Axis (~1 rpm) Scan Coverage 45 Precession (~1 rph) 1 minute Sun-Spacecraft Axis Downlink To Earth 3 minutes 1 hour

19 Scan Strategy Optical Axis 55 Spin Axis (~1 rpm) 1 Day Maps 45 Precession (~1 rph) Sun-Spacecraft Axis Spatial Coverage Downlink To Earth Angular Uniformity More than half the sky in a single day!

20 Scan Strategy EPIC Redundant Low-Cost & Mission Uniform Architecture Scan Coverage N-hits (1-day) Angular Uniformity* (6-months) Planck WMAP EPIC *<cos 2β> 2 + <sin 2β> 2 0 1

21 Far-Sidelobe Performance BICEP Sidelobe Performance BICEP Measurements Sky at 100 GHz 1e5 1e4 1e Sidelobe Map at 100 GHz 1 µk ~ 20% polarized Levels below 3 nk for most of the 3nK

22 EPIC Polarization Modulators EPIC-LC 6 single-band stepped HWPs 45 Steps every 24 hours 90 GHz Band Upscope: continuous HWP EPIC-C Focal Plane Modulators 200/300 GHz Band

23 EPIC Systematics Survey Brian Keating, Meir Shimon, Nicolas Ponthieu, Eric Hivon & Jamie Bock

24 EPIC Systematics Mission Concept Study Bock et al. -- astro-ph ) Simulated both 5 Low Cost and 60 CS missions Largely based on Shimon, Keating, Ponthieu & Hivon 2008 (PRD v77). Found excellent agreement with map-domain approach (Ponthieu & Hivon) Have adapted EPIC pipeline for effects on secondary science, as well as primary B modes (Miller, Shimon, & Keating astro-ph/ )

25 Systematic effects in real space differential beam offset (dipole IP effect) differential gain (monopole effect) differential FWHM (monopole effect) differential ellipticity (quadrupole effect) } Irreducible

26 Definitions

27 Scaling Laws

28 Spin Classification of Systematics The various spin characteristics and the mismatch with the required quadrupole allude to the role of scanning strategy

29 Irreducible Beam Systematic: Differential Ellipticity T 1 T 2 For an unpolarized point source - = Diff. ellipticity - Intrinsic, on the sky

30 B-Mode Polarization (1 ): Differential Ellipticity (Inst. Polarization) e

31 B-Mode Polarization (1 ) Differential Rotation (Cross Polarization)

32 Reducible Beam Systematic Differential Pointing (Instrumental Polarization) T 1 T 2 For an unpolarized point source - = Diff. pointing N.B. Both Differential ellipticity and pointing have an orientation angle which determines what fraction is converted to E or B.

33 EPIC Pipeline Comparison Map-domain (Ponthieu & Hivon) Frequency Domain (Shimon, Keating, Miller)

34 Requirements and Goals - LC Results

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36 37 37

37 Uniformity of Scan Strategy K. Gorski, Ponthieu, Hivon

38 Systematic Error Mitigation

39 Post-scanning Idealization Differential gain, beamwidth couple to the quadrupole of the scanning strategy Differential pointing couples to the dipole Experiments with reasonable scanning can benefit from throwing out the dipole and quadrupole from the data

40 Scan Strategy Issues & EPIC Work TBD ideal

41 Removing the dipole" refers to the multipoles of the scanning strategy, NOT to be confused with the "dipole and quadrupole beam systematic effect. Removing the dipole of the scanning strategy eliminates the first order pointing error. ideal Removing the dipole

42 Removing the quadrupole Removing the quadrupole asymmetry from the scanning strategy eliminates the differential gain and differential beamwidth effects. ideal

43 Medium Scale Mission

44 EPIC Challenges EPIC LC (30 cm aperture) EPIC CS (~3 meter aperture) Scientific Scope Beam Effects Cost Scan Speed vs. Stability Multichroic Refracting optics

45 In Search of an Optimum EPIC LC (30 cm aperture) Scientific Scope Beam Effects How to Broaden Scientific Scope with Minimal Cost Increase? EPIC CS (~3 meter aperture) Cost Scan Speed vs. Stability Multichroic Refracting optics What is the Optimal Angular

46 A 2 meter Mission Concept Single ~2 meter aperture Frequencies Resolution Detectors Lifetime Freq [GHz] GHz 8 at 100 GHz 1620 Bolometers 4 years θ FWHM [arcmin] N bol [#] K TEPS bolometers NET = 1.6 μk sec Weight = 2.5 μk arcmin ΔT pix =15 nk 2 noise margin No Waveplate => focal plane modulators? Galactic Science Band

47 Freq [GHz] Sensitivity Numbers for Science Workshop: 2 m θ FWHM [arcmin] N bol [#] AΩ/band [cm 2 sr] a -1/2 AΩ max /band NET [µk s] w p [cm 2 sr] b bolo band [µk-arcmin] (0.2) f 200 δt pix [nk] (0.04) f 4000 a Focal Totalplane is nested with 1620 highest frequency 610 bands in center, lowest frequency bands 1.4 at edge b Total unabberated throughput if entire telescope uses one band only c Sensitivity of one bolometer (T CMB ); in combined band using 2 bolometers per pixel d w p -1/2 = [8π NET bolo2 /(T mis N bol )] 1/2 (10800/π) e Sensitivity δt CMB in a 2 x 2 pixel (1σ) f Point source sensitivity in mjy (1σ) per beam without confusion Focal plane temperature T K Optical efficiency η opt 40% Lens temperature T lens 4 K Fractional bandwidth Δν/ν 30% Mirror temperature T opt 4 K Noise margin Mirror emissivity at 1 mm ε 1.0% Mission lifetime T life 4 years

48 Summary EPIC two ( three) realizations of a CMB inflation probe Need input on Optimization of angular resolution vs. science deliverables Neutrino mass limit vs. angular resolution (or weight) Dark energy constraints vs angular resolution (or weight) Ancillary science vs. angular resolution, frequency coverage Sensitivity How much is good enough? Do we need more? Frequency Coverage Is a 300 GHz band necessary? Is a 30 GHz band necessary? Is a very precise temperature measurement important? e.g. Non-gaussianity

49 Systematic Error Conclusions Some experimental approaches are generically good: modulate polarization w/out modulating beam shape; low 1/f noise; low polarization rotation through optics; low sidelobes In reality different instrument designs trade-off between different sources of systematic errors. many sources are instrument + scan strategy specific and they Interact in a complicated way with overall design Not clear that the issue of systematic errors gives preference for one design over another All designs will require careful analysis of calibration and systematic error mitigation To date no CMB experiment has fallen short of expectations because of systematic limitations