Epoch of Reionization last phase of cosmic evolution to be explored bench-mark in cosmic structure formation indicating the first luminous structures Cosmic reionization and other lunar radio studies Chris Carilli (NRAO)

z=5.80 z=5.82 z=5.99 z=6.28 Large scale CMB pol: z EoR =11+/-3 First observational constraints on cosmic reionization T TE EE Gunn-Peterson Effect: z EoR >= 6 Fan Page TT

Current observations: z EoR = 14 to 6 (Fan, Carilli, Keating 2006)  Not ‘event’, but complex process, large variance time/space  GP => occurs in ‘twilight zone’, opaque _obs  < 0.9 um Limited Diagnostics GP:  Ly  > 1e4 for f(HI)> 1e-3 => low f(HI) CMB pol = integral measure of  e => high f(HI)

Studying the pristine IGM into the reionization, and beyond: redshifted HI 21cm observations in range 30 – 200 MHz SKA goal:  Jy at 200 MHz Large scale structure: density, f(HI), T _spin 1e12M o 1e9M o

Lunar Advantage I: Interference 100 MHz z= MHz z=6 Destination: Moon! RAE

Ionospheric Opacity: p ~1 to 10 MHz  TIDs – ‘fuzz-out’ sources  ‘Isoplanatic patch’ = few deg = few km  Phase variation proportional to ^-2 Solution: ‘Rubber screen’ phase self-calibration Virgo A VLA 74 MHz Lane + 02 Lunar Advantage II: Ionospheric phase distortions

Remaining challenge: low frequency foreground  Coldest regions: T = 100  z)^-2.7 K  Highly ‘confused’: 3 sources/arcmin^2 with S _0.2 > 0.1 mJy Eberg 408 MHz Image (Haslam82) Solution: fitting in the spectral domain

HI 21cm Tomography of IGM Zaldarriaga z=   T _B (2’) = 10’s mK => DNR > 1e5  LOFAR rms (1000hr) = 80mK  SKA rms(100hr) = 4mK

z=3.62 Womble 1996 N(HI) = 1e e15 cm^-2, f(HI/HII) = 1e e-6 => Before reionization N(HI) =1e18 – 1e21 cm^-2 Cosmic Web (IGM) after reionization = Ly alpha forest (  <= 10))

z=12z=8 19mJy 130MHz Radio G-P (  =1%) 21 Forest (10%) Mini-halos (10%) Primordial disks (100%) Signal IV: Cosmic web before reionization: HI 21Forest Expect 0.05 to 0.5 sources/deg^2 at z> 6 with S _151 > 6 mJy z=12 z=8

GMRT 230 MHz – HI 21cm abs toward highest z radio AGN (z = 5.2) S 230 = 0.5Jy; rms (20km/s) = 5 mJy z(CO) GHz 1” Van Breugel et al. RFI = 20 kiloJy ! N(HI) < 1e20 (T s /100) cm^-2

 Only direct probe of host galaxy: dust, molecular gas  Coeval starburst/AGN: SFR ~ 1e3 M o /yr  2e10 M o of molecular gas = fuel for star formation  Early enrichment of heavy elements/dust: z sf > 8 J1148 VLA CO ” IRAM Molecular gas + fine structure lines: J z=6.42 t univ =0.87 Gyr [CII] CO

Cosmic Stromgren Spheres : Accurate z _host from CO: z=6.419+/0.001 Proximity effect: photons leaking from 6.32<z<6.419 ‘time bounded’ Stromgren sphere: R = 4.7 Mpc f(HI) = 1e-5 R^-3 (t qso /1e7) yrs White et al. 2003

Loeb & Rybicki 2000 Largest ‘bubbles’ at end of reionization

HI imaging of Cosmic Stromgren spheres around z > 6 QSOs 0.5 mJy  LOFAR ‘observation’: 0.5 f(HI) mJy  Pathfinders: Set first hard limits on f(HI) at end of cosmic reionization  Easily rule-out cold IGM (T _s < T _cmb ): signal = 360 mK Wyithe et al Mpc

VLA-VHF: 180 – 200 MHz Prime focus X-dipole Greenhill, Blundell (SAO Rx lab); 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

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

Focus: EoR signal (power spec, CSS, abs) Very wide field: full cross correlation of all dipoles Staged engineering approach: GB  Mileura07

PAPER: First images/spectra Cygnus A 1e4Jy Cas A 1e4Jy 3C Jy 3C Jy 140MHz 180MHz

Very low frequency (<30MHz): pre-reionization HI signal  Lunar imperative; eg. Baryon Oscillations (Barkana & Loeb) Very difficult to detect  Signal: 10 arcmin, 10mk => S _30MHz = 0.02 mJy  SKA sens in 1000hrs: T= 100( /200 MHz)^-2.7 K = 20000K at 30MHz => rms = 0.2 mJy Need > 10 SKAs Need DNR > 1e6 z=50 z=150

Lunar VLF science: 0.1 to 10 MHz Advantages Between Earth’s ionospheric cutoff and heliosphere/Galactic free-free cutoff Blocked from earth auroral emission RFI Protected ‘volume’ (ITU – 22.25) Easy deployment: Javelins, Roll-out, Rover, Inflatables Easy maintenance: ‘cheap’, high tolerance electronics, no moving parts

VLF science Coronal Mass Ejections and space weather: ‘early warning system’ – passive + remote sensing (Bastian) Extrasolar planetary radio bursts (Lazio)  ~ 1 – 100 MHz S ~ 0.1 – 100 mJy

Array of lunar sensors (Falcke/ASTRON) Moon as a neutrino detector: Cherenkov radiation from neutrinos in lunar regolith Geophones: lunar seismology

IPS/ISS angular/temporal broadening: 1MHz => 1deg, 5years Faraday rotation => no linear polarization High sky temperature Low power super computing: LOFAR/Blue Gene = 0.15MW Diffraction limit: how sharp is ‘knifes edge’? Lunar ionosphere: p = 0.2 to 1MHz (LUNA19, ’s)? Very low frequencies (<10MHz): Lunar challenges

ALMA on the moon: Why? No Troposphere – phase and opacity, eg. 650GHz (350  m): T rx = 125K,  =0.5, T sky =150K => Same sensitivity with 16 ants vs. 64 No wind, less gravity: lighter dishes Stable platform for interferometry Why not? Cryogenics: need 4K (HeII) for SIS Power: ALMA = 5-8 MW 5000m

Radio astronomy – Probing Cosmic Reionization First constraints: GP, CMBpol=> z EoR = 6 to 14 HI 21cm: most direct probe of reionization Low freq pathfinders: All-sky, PS, CSS, Abs. SKA: imaging of IGM Lunar advantages: Interference No ionosphere Relatively ‘easy’

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

END

All sky: SI deviations = Solution: spectral decomposition (eg. Morales, Gnedin…) 10’ FoV; SKA 1000hrs Power spectral analysis: Fourier analysis in 3D – different symmetries in freq space ( ie. Different spectral chan-chan correlation) Freq SignalForeground

Solution – RFI mitigation: location, location location… 100 people km^-2 1 km^ km^-2

‘Pathfinders’: PAST, LOFAR, MWA, VLA-VHF, … MWA prototype (MIT/ANU) LOFAR (NL) PAST (CMU/China)VLA-VHF (CfA/NRAO)

Main Experiment: Cosmic Stromgren spheres around z=6 to 6.5 SDSS QSOs (Wyithe & Loeb 2004) VLA-VHF 190MHz 250hrs 15’ 20 f(HI) mK 0.50+/-0.12 mJy  VLA spectral/spatial resolution well matched to expected signal: 7’, 1000 km/s  Set first hard limits on f(HI) at end of cosmic reionization (f(HI) < 0.3)  Easily rule-out cold IGM (T _s < T _cmb ): signal = 360 mK

LOFAR Hi-Band Antenna ( MHz) Westerbork Radio Observatory Paradigm shift: from steel to silicon. Past: a lot of steel to focus radiation on a single electronic receiver Future: many digital receivers and massive data processing synthesize virtual telescope in software

ARTICLE 22 (ITU Radio Regulations) Space services Section V – Radio astronomy in the shielded zone of the Moon 22.22§ 81)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: a)the frequency bands allocated to the space research service using active sensors; 22.24b)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 )In frequency bands in which emissions are not prohibited by Nos 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 The shielded zone of the Moon comprises the area of the Moon’s surface and an adjacent volume of space which are shielded from emissions originating within a distance of km from the centre of the Earth The level of harmful interference is determined by agreement between the administrations concerned, with the guidance of the relevant ITU-R Recommendations. Good “news” … The Moon is radio protected!  The back side of the moon is declared as a radio protected site within the ITU Radio Regulations  The IT Radio Regulations are an international treaty within the UN.  Details are specified in a published ITU Recommendation (this is a non-mandatory recommendation, but is typically adhered to).  Radio astronomy on the moon has been a long-standing goal, protected by international treaties!  Steps need to be taken to protect the pristine and clean nature of the moon.  Lunar communication on the far side needs to be radio quiet.

Tsiolkovsky crater (100 km diameter) 20°S 129°E Apollo 15 Tsiolkovsky crater

Lunar LOFAR: Distributed array of radio sensors  Start with N=100 antennas  Collecting area:  A eff =N  2 /8 (3 MHz; ~100 m) A eff ~ km 2 (17 football fields or ~400 m dish)  First prototype phase:  Antennas, power, computers, communication, dispatcher  Weight ~1000 kg (payload)  Needs only one Ariane V launch  Separation D = 1 km → 1000 km  Resolution ( /D): ~1.6° (D=1 km, 10 MHz) ~6’’ (D=1000 km, 10 MHz) ~ 1’ (D=1000 km, 1 MHz ) Remote antennas are added later

Ionosphere Opacity: p ~ 1 to 10MHz Phase errors  TIDs – ‘fuzz-out’ sources  ‘Isoplanatic patch’ = few deg = few km  Phase variation proportional to wavelength^2

Global reionization signature in low frequency HI spectra (Gnedin & Shaver 2003) double fast 21cm ‘deviations’ at 1e-4 wrt foreground Spectral index deviations of 0.001