SKA KSP: probing cosmic reionization and the first galaxies

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SKA KSP probing cosmic reionization and the
first galaxies Manchester, Oct 2007 Chris
Carilli (NRAO)
Ionized
Neutral
Reionized
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Chris Carilli (NRAO) Berlin June 29, 2005
WMAP structure from the big bang
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Realm of the Galaxies
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• Last phase of cosmic evolution to be explored
• Benchmark in cosmic structure formation
  indicating the formation of the first luminous
  objects.
• HI 21cm line is most direct, incisive probe of
  structure formation during, and process of,
  reionization.
• Radio(cm/mm) observations reveal the gas, dust,
  star formation, and AGN in the earliest galaxies

Dark Ages
Cosmic reionization
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Constraint I Gunn-Peterson Effect
End of reionization? f(HI) gt 1e-3 at z 6.3
f(HI) lt 1e-4 at z 5.7 IGM opaque at ?obs lt 1um
Fan et al 2006
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Constraint II CMB large scale polarization
Thompson scattering during reionization

• Scattered CMBquad. gt polarized
• Horizon scale 10s deg
• EE 1 TT
• ? 0.09/-0.03 gt zreion 11/-3

TT
TE
EE
Fan et al 2003
Page 06
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Fan, Carilli, Keating ARAA 2006

• Not event but complex process, large
  variance zreion 14 to 6
• Good evidence for qualitative change in nature
  of IGM at z6

ESO
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Local ioniz.?

• Current probes are all fundamentally limited in
  diagnostic power
• Need more direct probe of process of reionization
  HI 21cm line

ESO
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KSP part I Studying the pristine IGM into the
EOR using redshifted HI 21cm observations (100
200 MHz)

• Large scale structure
• cosmic density, ?
• neutral fraction, f(HI)
• Temp TK, TCMB, Tspin
• Heating Ly?, Xrays, shocks

1e13
1e9
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Signal I Global (all sky) reionization
signature in low frequency HI spectra
IGM heating TspinTK gt TCMB
Lya coupling TspinTK lt TCMB
130MHz
190MHz
Gnedin Shaver 03
21cm deviations lt 1e-4 wrt foreground
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Signal II HI 21cm Tomography of IGM Zaldarriaga
2003
z12
9
7.6

• ?TB(2) 10s mK
• SKA rms(100hr) 4mK
• LOFAR rms (1000hr) 80mK

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Signal III 3D Power spectrum analysis
??only
LOFAR
? f(HI)
SKA
McQuinn 06
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Cosmic Web after reionization Ly alpha forest at
z3.6 (? lt 10)
Womble 96
N(HI) 1e13 1e15 cm-2, f(HI/HII) 1e-5 --
1e-6 gt Before reionization N(HI) 1e18 1e21
cm-2
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Signal IV Cosmic web before reionization HI
21Forest
z12
z8
19mJy
130MHz

• Only method to study small scale structure
• expect 0.05 to 0.5 deg-2 at zgt 6 with S_151 gt
  6 mJy

• radio G-P (?1)
• 21 Forest (10)
• mini-halos (10)
• primordial disks (100)

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Pathfinders First light 2007/2008
MWA (MIT/ANU)
LOFAR (NL)
PAST (CMU/China)
PAPER Berk/NRAO
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Challenge I Low frequency foreground hot,
confused sky Eberg 408 MHz Image (Haslam 1982)
Coldest regions T 100 (?/200 MHz)-2.6
K Highly confused 1 source/deg2 with S140 gt 1
Jy
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• Solution spectral decomposition (eg. Morales,
  Gnedin)
• Foreground non-thermal featureless over
  100s MHz
• Signal fine scale structure on scales few MHz

Cygnus A
500MHz
5000MHz

• Remove low order polynomial or other smooth
  function?
• Cross correlation in channels, or 3D power
  spectrum

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Challenge II Ionospheric phase errors varying
e- content
TID
100
-100
74MHz Lane 03

• Isoplanatic patch few deg few km
• Phase variation proportional to wavelength2
• Solution Wide field rubber screen phase
  self-calibration

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Challenge III RFI location, location,
location
100 people km-2
1 km-2
0.01 km-2
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KSP part II -- first galaxies CO redshift
coverage
Epoch of Reionization

• First galaxies standard molecular transitions
  redshift to cm regime
• Total gas mass
• Gas dynamics
• Gas excitation
• High density gas tracers

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First galaxies -- Radio astronomy into cosmic
reionization z 6 QSO host galaxies molecular
gas and dust
VLA
z6.42
50K
PdBI
FWHM350 km/s
Radio-FIR correlation

• Mdust 1e8 Mo
• Dust heating star formation or AGN?
• Follows Radio-FIR correlation SFR 3000 Mo/yr

• Giant reservoirs of molecular gas 2e10 Mo
  fuel for star formation.
• Currently 3 solid detections, 1 likely at z6

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J114852 VLA imaging of CO3-2
VLA imaging of gas at subkpc resolution
0.4res
rms50uJy at 47GHz
1 5.5kpc
0.15 res

• Separation 0.3 1.7 kpc
• TB 20K gt Typical of starburst nuclei

• Not just circumnuclear disk.
• Mdyn 4e10Mo Mgas gtgt Mbulge 1e12 Mo
  predicted by M-?
• Only probe of host galaxy

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CII 158um ISM gas cooling line at z6.4
30m 256GHz Maiolino etal

• C workhorse line for zgt6 galaxies with ALMA
• Structure identical to CO 3-2 ( 5 kpc) gt
  distributed gas heating star formation?
• SFR 6.5e-6 LCII 3000 Mo/yr

CII PdBI Walter et al.
CII CO 3-2
1
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Higher Density (ncrgt1e4 cm-3) Tracers HCN, CN,
HCO
HCO 1-0
HCN 1-0
Riechers

• Linearly correlated with FIR gt dense gas
  directly associated with star forming clouds
• Lines 5-10x fainter than CO
• ncr gt 1e7cm-3 for higher orders gt higher
  order not (generally) excited?
• Dense gas tracers exclusive regime of cm
  telescopes

200uJy
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Building a giant elliptical galaxy SMBH at
tuniv lt 1Gyr
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10.5

• Multi-scale simulation isolating most massive
  halo in 3 Gpc3 (co-mov)
• Stellar mass 1e12 Mo forms in series (7) of
  major, gas rich mergers from z14, with SFR 1e3
  - 1e4 Mo/yr
• SMBH of 2e9 Mo forms via Eddington-limited
  accretion mergers
• Evolves into giant elliptical galaxy in massive
  cluster (3e15 Mo) by z0

8.1
Li, Hernquist, Roberston, Dave ..
6.5

• Enrichment of heavy elements, dust starts early
  (z gt 8) good news for radio astronomy
• Extreme and rare objects 100 SDSS z6 QSOs on
  entire sky
• Integration times of hours to days to detect
  HyLIGRs

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The need for collecting area pushing to normal
galaxies at high redshift -- spectral lines
cm telescopes low order molecular transitions
(sub)mm high order molecular lines fine
structure lines
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The need for collecting area continuum A
Panchromatic view of galaxy formation
Arp 220 vs z
cm Star formation, AGN
(sub)mm Dust, molecular gas
Near-IR Stars, ionized gas, AGN
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Radio astronomy Reionization and 1st galaxies

• Twilight zone study of first light limited to
  near-IR to radio wavelengths
• First constraints GP, CMBpol gt reionization is
  complex and extended zreion 6 to 14
• HI 21cm most direct probe of reionization
• - Low freq pathfinders All-sky, PS, CSS, Abs
• - SKA imaging of IGM
• First galaxies cm/mm -- gas, dust, star
  formation, AGN

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END
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Signal VI pre-reionization HI signal richest
of all cosmological data sets eg. Baryon
Oscillations (Barkana Loeb)

• Very difficult to detect !
• z50 gt n 30 MHz
• Signal 30 arcmin, 50 mk gt S_30MHz 0.1 mJy
• SKA sens in 1000hrs
• T_fg 20000K gt
• rms 0.2 mJy

z50
z150
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Destination Moon!

• No interference (ITU protected zone)
• No ionosphere (?)
• Easy to deploy and maintain (high tolerance
  electronics no moving parts)

10MHz
Needed for probing Dark ages zgt30 gt freq lt
50 MHz
RAE2 1973
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