Lunatic fringe: probing the dark ages from the dark side of the MoonC. Carilli (NRAO)

Enchanted Skies

Socorro, NM

Sept. 2008

Ionized f(HI) ~ 0

Neutral f(HI) ~ 1

Reionized f(HI) ~ 1e-5

History of Baryons in the Universe

Chris Carilli (NRAO)

Berlin June 29, 2005

WMAP – structure from the big bang (/~ 1e-5)

Hubble Space Telescope Realm of the Galaxies / ~ 1e5

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

Dark Ages

Twilight Zone

Epoch of Reionization

• Epoch?• Process?• Sources?

Dark Ages

Twilight Zone

Pushing into reionization: most distant galaxies and quasars

SDSS J1148+5251

tuniv ~ 0.87 Gyr

Barkana and Loeb 2001

Gunn-Peterson Effect

z

First constraints on cosmic reionization • Gunn-Peterson Effect toward z~6 QSO = absorption by the neutral intergalactic medium (IGM) at tuniv < 1Gyr

Fan et al 2006

0.87 Gyr

1.0

• From tuniv ~ 0.87 to 1.0 Gyr, neutral fraction changes by order of magnitude

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Gnedin 03

Reionization: the movie

8Mpc comoving

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)

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

Multiple experiments under-way

MWA (Oz; MIT/CfA/ANU) LOFAR (NL)

21CMA (China)

21CMA (China)

Takla Makan Desert

10,000 TV antennas

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Challenge I: Low frequency foreground – hot, confused sky

Eberg 408 MHz Image (Haslam + 1982)

Cosmological signal ~ 0.00001 x Sky

Fluctuations in ionospheric electron content causes interferometric phase errors at low radio frequencies ~ ‘radio seeing’

Challenge II: Ionospheric ‘seeing’

Virgo A 6 hrs VLA 74 MHz Lane + 02

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15’

Challenge II: Ionospheric ‘seeing’

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!

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

Project abandoned: Digital TV

KNMD Ch 9

150W at 100km

RFI mitigation: location, location location…

100 people km^-2

1 km^-2

0.01 km^-2

(Briggs 2005)

Murchison widefield array (MIT - Melbourne)

Precision Array to Probe the Epoch of Reionization

(Berkeley -- NRAO)

Radio astronomers going to the ends of the Earth

Ultimate location: the dark side of the Moon

Long History of Lunar Low Freq Telescope

Gorgolewski 1965: Ionospheric opacity

• Ionosphere opaque below 10 MHz

• Interstellar medium opaque below 0.1 MHz

• tuniv < 10Myr => not (very) relevant for HI 21cm studies, ‘beyond dark ages’

Lunar window

ion. cutoff ~ 30m

ISM cutoff ~ 3km

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…”

Ares IAres I Ares VAres V

Ares V

• 10m diameter faring

• Lifting power = 65 tons to Moon

Heavy lifting: capitalize on future launch vehicles

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

Advantage II: Interference

Lunar shielding of Earth’s auroral emission at low freq (Radio Astronomy Explorer 1975)

Alexander + 1975

12MHz

The Moon is radio protectedARTICLE 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 Moon31 emissions causing harmful interference to radio astronomy observations32 and to other users of passive services shall be prohibited in the entire frequency spectrum except in the following bands: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.

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)

Deployment

• Javelin

• ROLS: polyimide circuit-imprinted film

• Dipoles: robotic with rover

• Dipoles: manually

Array of lunar sensors (Falcke)

• ‘Lunar internet’

• Cherenkov radiation from neutrinos passing through the lunar regolith

• Geophones: lunar seismology

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

Tsiolkovsky crater

(100 km diameter)

20°S 129°E

Apollo 15But how sharp is the knife’s edge?

Energy solutions: polar craters of eternal darkness, peaks of eternal light = eternal power

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

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!

+ ARES V Launch fee ~ $700M

Total ~ $2G

Budget WAG (Hewitt/LARC)

European Aeronautic Defense and Space Corporation/ASTRON (Falcke)

• Payload = 1000 kg (Ariane V)

• 100 antennas at 1-10 MHz ~ 1/10 SKA

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Say, its only a PAPER moonSailing over a cardboard seaBut it wouldn't be make-believeIf you believed in me

END

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 tuniv ~ 0.4Gyr

Page et al. 2006

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.

Combined CMB + GP constraints on reionization

Current probes are all fundamentally limited in diagnostic power: Need more direct probe of process of reionization

Doppler effect – follow those lines!

The amazing and EXPANDING universe

3/13/22 ;)(2

1 −∝∝=>= tdtdR

tRR

GMmdtdR

m

Contents of the Universe:

•70% Dark Energy

•27% Dark Matter

•3% Baryons

Focus: Reionization (power spec,CSS,abs)

C. Carilli, A. Datta (NRAO), J. Aguirre (Penn)

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

100MHz 200MHz

BEE2: 5 FPGAs, 500 Gops/s

CygA 1e4Jy

PAPER/WA -- 4 Ant, July 2007

RMS ~ 1Jy; DNR ~ 1e4

Parsons et al. 2008

1e4Jy