1. Lunatic fringe: probing the dark ages from the dark side of the Moon C. Carilli (NRAO) Enchanted Skies Socorro, NM Sept. 2008

2. Ionized f(HI) ~ 0 Neutral f(HI) ~ 1 Reionized f(HI) ~ 1e-5 History of Baryons in the Universe

3. Chris Carilli (NRAO) Berlin June 29, 2005 WMAP – structure from the big bang (  /  ~ 1e-5)

4. Hubble Space Telescope Realm of the Galaxies  /  ~ 1e5

5. Dark Ages Twilight Zone Epoch of Reionization Last phase of cosmic evolution to be tested Bench-mark in cosmic structure formation indicating the first luminous structures

6. Dark Ages Twilight Zone Epoch of Reionization Epoch? Process? Sources?

7. Dark Ages Twilight Zone Pushing into reionization: most distant galaxies and quasars SDSS J1148+5251 t univ ~ 0.87 Gyr

8. Barkana and Loeb 2001 Gunn-Peterson Effect z

9. First constraints on cosmic reionization Gunn-Peterson Effect toward z~6 QSO = absorption by the neutral intergalactic medium (IGM) at t univ < 1Gyr Fan et al 2006 0.87 Gyr 1.0 From t univ ~ 0.87 to 1.0 Gyr, neutral fraction changes by order of magnitude

10. Gnedin 03 Reionization: the movie 8Mpc comoving

11. Radio => Hydrogen Gas Most direct probe of the neutral IGM during, and prior to, cosmic reionization, is the 21cm line of neutral hydrogen HI spin flip => 21cm radiation (1420 MHz)

12.  3D ‘tomography’ of the evolution of the large scale structure of the IGM: “richest of all cosmological data sets” (Loeb)  Low frequencies: Universal expansion (‘redshift’) implies HI 21cm line will be observed at < 200 MHz  Weak signal requires very large area telescopes ‘Square kilometer array’ 400Myr, 109MHz 600Myr, 142 MHz 800Myr, 178MHz

13. Multiple experiments under-way MWA (Oz; MIT/CfA/ANU) LOFAR (NL) 21CMA (China)

14. Takla Makan Desert 10,000 TV antennas

16. Challenge I: Low frequency foreground – hot, confused sky Eberg 408 MHz Image (Haslam + 1982) Cosmological signal ~ 0.00001 x Sky

17. Fluctuations in ionospheric electron content causes interferometric phase errors at low radio frequencies ~ ‘radio seeing’ Challenge II: Ionospheric ‘seeing’

18. Virgo A 6 hrs VLA 74 MHz Lane + 02 15’ Challenge II: Ionospheric ‘seeing’

19. Challenge III: Interference 100 MHz z=13 200 MHz z=6 Solutions -- RFI Mitigation (Ellingson06)  Digital filtering: multi-bit sampling for high dynamic range (>50dB)  Beam nulling/Real-time ‘reference beam’  LOCATION!

20. VLA-VHF: 180 – 200 MHz Prime focus CSS search Greenhill, Blundell (SAO); Carilli, Perley (NRAO) Leverage: existing telescopes, IF, correlator, operations  $110K D+D/construction (CfA)  First light: Feb 16, 05  Four element interferometry: May 05  First limits: Winter 06/07

21. Project abandoned: Digital TV KNMD Ch 9 150W at 100km

22. RFI mitigation: location, location location… 100 people km^-2 1 km^-2 0.01 km^-2 (Briggs 2005)

23. Murchison widefield array (MIT - Melbourne) Precision Array to Probe the Epoch of Reionization (Berkeley -- NRAO) Radio astronomers going to the ends of the Earth

24. Ultimate location: the dark side of the Moon

25. Long History of Lunar Low Freq Telescope Gorgolewski 1965: Ionospheric opacity Ionosphere opaque below 10 MHz Interstellar medium opaque below 0.1 MHz t univ not (very) relevant for HI 21cm studies, ‘beyond dark ages’ Lunar window ion. cutoff ~ 30m ISM cutoff ~ 3km

26. Return to moon is Presidential national security directive (an order, not a request). Summary of STScI Workshop, Mario Livio, Nov. 2006 “The workshop has identified a few important astrophysical observations that can potentially be carried out from the lunar surface. The two most promising in this respect are: (i)Low-frequency radio observations from the lunar far side to probe structures in the high redshift (10 < z< 100) universe and the epoch of reionization (ii)Lunar ranging experiments…”

27. Ares I Ares V 10m diameter faring Lifting power = 65 tons to Moon Heavy lifting: capitalize on future launch vehicles

28. Clementine (NRL) star tracker Lunar advantage I: ultra-thin ionosphere  Soviet LUNA orbiters in 1970’s detected plasma layer > 10 km above surface  Apollo surface+subsatellite: detected photoionized layer extending to 100km  p = 0.2 to 1 MHz  large day/night variation => two weeks of ionosphere-free night-time

29. Advantage II: Interference Lunar shielding of Earth’s auroral emission at low freq (Radio Astronomy Explorer 1975) Alexander + 1975 12MHz

30. The Moon is radio protected ARTICLE 22 (ITU Radio Regulations) Space services Section V – Radio astronomy in the shielded zone of the Moon 22.22 § 8 1) In the shielded zone of the Moon 31 emissions causing harmful interference to radio astronomy observations 32 and to other users of passive services shall be prohibited in the entire frequency spectrum except in the following bands: 31 32 22.23 a) the frequency bands allocated to the space research service using active sensors; 22.24 b) the frequency bands allocated to the space operation service, the Earth exploration-satellite service using active sensors, and the radiolocation service using stations on spaceborne platforms, which are required for the support of space research, as well as for radiocommunications and space research transmissions within the lunar shielded zone. 22.25 2) In frequency bands in which emissions are not prohibited by Nos. 22.22 to 22.24, radio astronomy observations and passive space research in the shielded zone of the Moon may be protected from harmful interference by agreement between administrations concerned.

31. Other advantages Easier deployment: robotic or human Easier maintenance (no moving parts) Less demanding hardware tolerances Very large collecting area, undisturbed for long periods (no weather, no animals, not many people)

32. Deployment Javelin ROLS: polyimide circuit-imprinted film Dipoles: robotic with rover Dipoles: manually

33. Array of lunar sensors (Falcke) ‘Lunar internet’ Cherenkov radiation from neutrinos passing through the lunar regolith Geophones: lunar seismology

34. Apollo 15 Array data rates (Tb/s) >> telemetry limits, requiring in situ processing, ie. low power super computing (LOFAR/Blue Gene = 0.15MW) RFI shielding: How far around limb is required? Thermal cycling (mean): 120 K to 380 K Radiation environment Regolith: dielectric/magnetic properties Lunar challenges Lunar shielding at 60kHz Takahashi + Woan

35. Tsiolkovsky crater (100 km diameter) 20°S 129°E Apollo 15 But how sharp is the knife’s edge? Energy solutions: polar craters of eternal darkness, peaks of eternal light = eternal power

36. DALI - LAMA: A path to enlightenment NASA funded joint design study Dark Ages Lunar Interferometer (Lazio) Lunar Array for Measuring 21cm Anisotropies (Hewitt) Science (Loeb, Furlanetto) Science requirements (Carilli, Taylor) Antennas (Bradley, MacDowall) Receivers (Backer, Ellingson) Correlator (Ford, Kasper) Data communication (Ford, Neff) Site selection (Hoffman, Burns) Deployment (de Weck, DeMaio) Engineering: power/mech/therm Goal: Decade Survey 2010 white paper with mission concept, (rough) costing, and technological roadmap

37. 2010 -- 2020: technology development <2010: mission concept study 2020 -- 2025: Design/Fabrication/Test 2026+: operations Interim programs Orbiter: RFI, ion First dipoles: environ., phase stability Global signal Very long range planning!

38. + ARES V Launch fee ~ $700M Total ~ $2G Budget WAG (Hewitt/LARC)

39. European Aeronautic Defense and Space Corporation/ASTRON (Falcke) Payload = 1000 kg (Ariane V) 100 antennas at 1-10 MHz ~ 1/10 SKA

40. Say, its only a PAPER moon Sailing over a cardboard sea But it wouldn't be make-believe If you believed in me

41. END

42. CMB large scale polarization -- Thomson scattering during reionization   Scattering => polarized   Large scale: horizon scale at reionization ~ 10’s deg  Signal is weak: only 1% of T => finite ionization persisting to t univ ~ 0.4Gyr Page et al. 2006

43. Combined CMB + GP constraints on reionization Not ‘event’ but complex process, large variance in space and time, starting ~ 400 Myr after Big Bang, ending ~ 800 Myr after BB.

44. Combined CMB + GP constraints on reionization Current probes are all fundamentally limited in diagnostic power: Need more direct probe of process of reionization

45. Doppler effect – follow those lines!

46. The amazing and EXPANDING universe Contents of the Universe: 70% Dark Energy 27% Dark Matter 3% Baryons

47. Focus: Reionization (power spec,CSS,abs) C. Carilli, A. Datta (NRAO), J. Aguirre (Penn)

48. PAPER: Staged Engineering Broad band sleeve dipole + flaps 8 dipole test array in GB (06/07) => 32 station array in WA (2008) to 256 (2009) FPGA-based ‘pocket correlator’ from Berkeley wireless lab: easily scale-able S/W Imaging, calibration, PS analysis: AIPY + Miriad/AIPS => Python + CASA, including ionospheric ‘peeling’ calibration 100MHz200MHz BEE2: 5 FPGAs, 500 Gops/s

49. CygA 1e4Jy PAPER/WA -- 4 Ant, July 2007 RMS ~ 1Jy; DNR ~ 1e4 Parsons et al. 2008 1e4Jy