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LÕLLiÃʅiÀiÊ>˜`Ê̅iÀi°ÊÛi˜ÌÕ>ÞÊ̅iÃiÊLÕLLiÃʓiÀ}i`Ê
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Epoch of Reionization/Cosmic Dawn Science with SKA
/ˆ“i\Ê
7ˆ`̅ʜvÊvÀ>“i\Ê
"LÃiÀÛi`ÊÜ>Ûii˜}̅\Ê
-ˆ“Տ>Ìi`ʈ“>}iÃʜvÊÓ£‡Vi˜Ìˆ“iÌiÀÊÀ>`ˆ>̈œ˜ÊŜÜʅœÜʅÞ`Àœ}i˜Ê
}>ÃÊÌÕÀ˜Ãʈ˜ÌœÊ>Ê}>>ÝÞÊVÕÃÌiÀ°Ê/…iÊ>“œÕ˜ÌʜvÊÀ>`ˆ>̈œ˜Ê­Ü…ˆÌiʈÃÊ
…ˆ}…iÃÌÆʜÀ>˜}iÊ>˜`ÊÀi`Ê>Àiʈ˜ÌiÀ“i`ˆ>ÌiÆÊL>VŽÊˆÃʏi>ÃÌ®ÊÀiyiVÌÃÊ
LœÌ…Ê̅iÊ`i˜ÃˆÌÞʜvÊ̅iÊ}>ÃÊ>˜`ʈÌÃÊ`i}Àiiʜvʈœ˜ˆâ>̈œ˜\Ê`i˜Ãi]Ê
iiVÌÀˆV>ÞʘiÕÌÀ>Ê}>ÃÊ>««i>ÀÃÊ܅ˆÌiÆÊ`i˜Ãi]ʈœ˜ˆâi`Ê}>ÃÊ>««i>ÀÃÊ
L>VŽ°Ê/…iʈ“>}iÃʅ>ÛiÊLii˜ÊÀiÃV>i`Ê̜ÊÀi“œÛiÊ̅iÊivviVÌʜvÊVœÃ“ˆVÊ
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̅iÊÜ>Ûii˜}̅°
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Ê̅iÊ}>ÃʈÃʘiÕÌÀ>°
/…iÊ܅ˆÌiÊ>Ài>ÃÊ>ÀiÊ
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}ˆÛiÊÀˆÃiÊ̜Ê̅iÊwÀÃÌÊ
ÃÌ>ÀÃÊ>˜`ʵÕ>Ã>Àð
әäʓˆˆœ˜ÊÞi>ÀÃ
ΰäʓˆˆœ˜Êˆ}…̇Þi>ÀÃ
ΰÎʓiÌiÀÃ
>ˆ˜ÌÊÀi`Ê«>ÌV…iÃ
ŜÜÊ̅>ÌÊ̅iÊÃÌ>ÀÃÊ
>˜`ʵÕ>Ã>ÀÃʅ>ÛiÊ
Li}՘Ê̜ʈœ˜ˆâiÊ̅iÊ
}>ÃÊ>ÀœÕ˜`Ê̅i“°
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Ó°nʓiÌiÀÃ
/…iÃiÊLÕLLiÃʜv
ˆœ˜ˆâi`Ê}>ÃÊ}ÀœÜ°
Jonathan Pritchard !
Co-chair EoR-SWG
{Èäʓˆˆœ˜ÊÞi>ÀÃ
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iÜÊÃÌ>ÀÃÊ>˜`
µÕ>Ã>ÀÃÊvœÀ“Ê>˜`Ê
VÀi>ÌiÊ̅iˆÀʜܘÊ
LÕLLið
x{äʓˆˆœ˜ÊÞi>ÀÃ
{°Èʓˆˆœ˜Êˆ}…̇Þi>ÀÃ
Ó°£Ê“iÌiÀÃ
/…iÊLÕLLiÃÊ>Ài
Li}ˆ˜˜ˆ˜}Ê̜Ê
ˆ˜ÌiÀVœ˜˜iVÌ°
ÈÓäʓˆˆœ˜ÊÞi>ÀÃ
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Ó°äʓiÌiÀÃ
/…iÊLÕLLiÃʅ>ÛiÊ
“iÀ}i`Ê>˜`ʘi>ÀÞÊ
Ì>Ži˜ÊœÛiÀÊ>ÊœvÊë>Vi°
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£°nʓiÌiÀÃ
/…iʜ˜ÞÊÀi“>ˆ˜ˆ˜}Ê
˜iÕÌÀ>Ê…Þ`Àœ}i˜ÊÊ
ˆÃÊVœ˜Vi˜ÌÀ>Ìi`ÊÊ
ˆ˜Ê}>>݈ið
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}>>ÝÞÊvœÀ“>̈œ˜°Ê"˜iÊÃiÌʜvʵÕiÃ̈œ˜ÃÊVœ˜ViÀ˜ÃÊ̅iʓ>ÃÈÛiÊ
L>VŽÊ…œiÃʈ˜Ê̅iÊVi˜ÌiÀÃʜvÊ}>>݈iðÊ"ÛiÀÊ̅iÊ«>ÃÌÊ`iV>`iÊ>Ç
Àœ˜œ“iÀÃʅ>ÛiÊÀi>ˆâi`Ê̅>ÌÊ>“œÃÌÊiÛiÀÞÊ}>>ÝÞʈ˜Ê̅iÊ«ÀiÇ
i˜Ì‡`>ÞÊ՘ˆÛiÀÃi]ʈ˜VÕ`ˆ˜}ʜÕÀʜܘʈŽÞÊ7>Þ]ʅœÃÌÃÊ>ʓ>Ç
, " -Ê* " 6 Ê­ ˆ   Õ Ã Ì À > Ì ˆ œ ˜® ÆÊÊ
Ê 1 , / / " ]Ê , " Ê- " - Ê ÊÊ
, + 1 - /Ê > À Û > À `Ê1 ˜ ˆ Û i À à ˆ Ì ÞÊ­ à ˆ “ Õ  > Ì ˆ œ ˜ î
UK EoR-SWG members:!
Filipe Abdalla (UCL)!
Epoch of Reionization Science Working Group
Anna
" , ÊBonaldi
/ " Ê 8 * " , (Manchester)!
}ÀœÜ̅ÊëÕÀÌÃ]Ê̅iÊ>VVÀï˜}Ê}>ÃÊň˜iÃʓÕV…Ê“œÀiÊLÀˆ}…̏ÞÊ
iÃi˜Ì>̈ÛiÊÃÌ>̈Ã̈V>ÊÃ>“«iʜvʜÕÀÊ՘ˆÛiÀÃiÊ>˜`Ê܈̅ʅˆ}…Ê
̅>˜Ê̅iÊi˜ÌˆÀiÊÀiÃÌʜvÊ̅iÊ}>>ÝÞ]Ê«Àœ`ÕVˆ˜}Ê>ʵÕ>Ã>À°Ê/…iÊ
i˜œÕ}…ÊÀi܏Ṏœ˜Ê̜ÊV>«ÌÕÀiÊ`Ü>ÀvÊ}>>݈iðÊ/…iÊȓՏ>̈œ˜Ê
i>ÃÕÀˆ˜}Ê̅iÊ-“>‡-V>iÊ*œÜiÀÊ-«iVÌÀՓʜvÊ
œÃ“ˆVÊi˜ÃˆÌÞÊ
Chair:
Leon
Koopmans
(Groningen)!
Emma
Chapman (UCL)!
ÕVÌÕ>̈œ˜ÃÊ̅ÀœÕ}…ÊÓ£ÊV“Ê/œ“œ}À>«…ÞÊ*ÀˆœÀÊ̜Ê̅iÊ«œV…ÊÊ
-œ>˜Êˆ}ˆÌ>Ê-ŽÞÊ-ÕÀÛiÞʅ>ÃÊÀiÛi>i`Ê̅>ÌʵÕ>Ã>ÀÃÊ܈̅ÊL>VŽÊ
>ÃœÊ˜ii`ÃÊ̜ÊÌÀ>ViÊ̅iÊ«Àœ«>}>̈œ˜ÊœvÊ̅iʈœ˜ˆâˆ˜}ÊÀ>`ˆ>̈œ˜Ê
œvÊ-ÌÀÕVÌÕÀiʜÀ“>̈œ˜°ÊLÀ>…>“ÊœiLÊ>˜`Ê>̈>ÃÊ<>`>ÀÀˆ>}>ʈ˜Ê
…œiÃʜvʓœÀiÊ̅>˜Ê>ÊLˆˆœ˜Ê܏>Àʓ>ÃÃiÃÊ>Ài>`ÞÊi݈ÃÌi`Ê>ÌÊ>Ê
Àœ“Ê̅iÊ}>>݈iÃÊ̅ÀœÕ}…Ê̅iÊÃÕÀÀœÕ˜`ˆ˜}Ê}>Ã]Ê>Ê«ÀœViÃÃʓœ`‡
Co-chairs:
Garrelt
Mellema
(Stockholm)!
Ilian
Iliev (Sussex)!
*…ÞÈV>Ê,iۈiÜÊiÌÌiÀÃ]Ê6œ°Ê™Ó]Ê
œ°ÊÓ£]Ê*>«iÀÊ œ°ÊÓ££Îä£ÆÊ>ÞÊÓx]ÊÓää{°ÊÊ
VœÃ“ˆVÊ>}iʜvʜ˜iÊLˆˆœ˜ÊÞi>ÀðʜÜÊ`ˆ`ÊÃÕV…Ê“>ÃÈÛiÊL>VŽÊ
ii`ʜ˜ÞÊÛiÀÞÊVÀÕ`iÞÊÜÊv>À°Ê"LÃiÀÛiÀÃʓ>ÞÊÜiÊÃiiÊÀiˆœ˜ˆâ>‡
*Ài«Àˆ˜ÌÊ>Û>ˆ>LiÊ>ÌÊ>À݈۰œÀ}É>LÃÉ>ÃÌÀœ‡«…ÉäΣӣÎ{
ˆœ˜ÊLivœÀiÊ̅iœÀˆÃÌÃÊ>ÀiÊ>LiÊ̜ÊvœÀiV>ÃÌÊ܅>ÌÊ̅iÞÊŜՏ`ÊÃii°
!/…ˆÃÊVœ“Lˆ˜i`ʜLÃiÀÛ>̈œ˜>Ê>˜`Ê̅iœÀïV>ÊivvœÀÌÊŜՏ`Ê
!
Jonathan Pritchard (Imperial) …œiÃÊVœ“iÊ̜Êi݈ÃÌÊÜÊi>ÀÞ¶Ê7…ÞÊ`ˆ`Ê̅iÞÊÃ̜«Ê}ÀœÜˆ˜}¶
Mike
Jones (Oxford)>ÌÕÀi]Ê6œ°Ê{ÎÎ]ÊÊ
/…iÊ-Ì>ÌiʜvÊ̅iÊ1˜ˆÛiÀÃi°Ê*iÌiÀÊ
œiÃʈ˜Ê
˜œÌ…iÀÊÃiÌÊVœ˜ViÀ˜ÃÊ̅iÊÈâiÊ`ˆÃÌÀˆLṎœ˜ÊœvÊ}>>݈iðÊ/…i‡
œÀˆÃÌÃÊLiˆiÛiÊ̅>ÌÊ̅iÊՏÌÀ>ۈœiÌÊÀ>`ˆ>̈œ˜Ê«Àœ`ÕVi`ÊLÞÊ`Ü>ÀvÊ
}>>݈iÃÊ`ÕÀˆ˜}Ê̅iÊi«œV…ÊœvÊÀiˆœ˜ˆâ>̈œ˜Ê…i>Ìi`Ê̅iÊVœÃ“ˆVÊ
}>ÃÊ>˜`ÊÃÕ««ÀiÃÃi`Ê̅iÊvœÀ“>̈œ˜ÊœvʘiÜʏœÜ‡“>ÃÃÊ}>>݈iðÊ
œÜÊ`ˆ`Ê̅ˆÃÊÃÕ««ÀiÃȜ˜Ê՘vœ`ʜÛiÀÊ̈“i¶Ê7…ˆV…ÊœvÊ̅iÊ
`Ü>ÀvÊ}>>݈iÃÊÜiÊw˜`Ê̜`>ÞÊÜiÀiÊ>Ài>`Þʈ˜Êi݈ÃÌi˜ViÊ>ÌÊ̅iÊ
«>}iÃÊÓ{nqÓxÈÆÊ>˜Õ>ÀÞÊÓx]ÊÓääx°
ˆÀÃÌʈ}…Ì°ÊLÀ>…>“ÊœiL°ÊiVÌÕÀiʘœÌiÃÊvœÀÊ̅iÊ--‡iiÊ7ˆ˜ÌiÀÊ
-V…œœ]Ê«ÀˆÊÓääÈ°Ê>À݈۰œÀ}É>LÃÉ>ÃÌÀœ‡«…ÉäÈäÎÎÈä
…>Ș}ÊÕLLi½ÃÊ-…>`œÜÃ\Ê/…iÊ-i>ÀV…ÊvœÀÊ>>݈iÃÊ>ÌÊ̅iÊ`}iÊÊ
See white paper: Mellema+ 2013 (arXiv:1210.0197)
œvÊ/ˆ“i°ÊivvÊ>˜ˆ«i°ÊˆÊ>˜`Ê7>˜}]ÊÓääÈ°
œÃ“œœ}ÞÊ>ÌʜÜÊÀiµÕi˜VˆiÃ\Ê/…iÊÓ£ÊV“Ê/À>˜ÃˆÌˆœ˜Ê>˜`Ê̅iʈ}…‡
SKA-LOW
Western Australia targets EoR signal at 50MHz-250MHz
UK-SKA Birmingham 2014
Jonathan Pritchard
The first billion years
CMB
Reionization marks the
limits of current
observations
Dark ages
Cosmic Dawn
Reionization
Galaxy !
formation
UK-SKA Birmingham 2014
Jonathan Pritchard
The first billion years
CMB
Dark ages
Cosmic Dawn
Reionization
Galaxy !
formation
UK-SKA Birmingham 2014
Reionization marks the
limits of current
observations
When did the first
galaxies form?
When did the first !
black holes form?
How did reionization
proceed?
How do galaxies form
and evolve?
Jonathan Pritchard
More needed...
Age of Universe=
QSO
CMB
∫
HUDF
redshift=
Existing observations leaves much unanswered
Possible hints of neutral hydrogen at z~7, e.g. z=7 QSO, LAE/LBG ratio
By 2020: possible advances...
1) Planck polarisation could constrain redshift and duration of reionization!
2) HST+JWST will have observed bright end of luminosity function to z~12
(faint end will still be incomplete; connection to ionizing photons may still be unclear)!
3) Little advance in QSO (more at z~7) - wait for Euclid in 2020 to push to z~8!
4) LAE surveys into EoR will be more advanced (HSC) - maybe clustering => patchy reionization?
SKA will map out details of reionization and cosmic dawn
UK-SKA Birmingham 2014
Jonathan Pritchard
More than reionization
!
Brightness [mK]
• 21 cm fluctuations contain wealth of information!
- Lyman alpha fluctuations => star formation rate and first galaxies!
- Temperature fluctuations => X-ray sources and first black holes!
- Neutral fraction fluctuations => topology of reionization!
- Density fluctuations => cosmology
First galaxies
Reionization!
begins
Dark Ages
Heating begins
50
Pritchard
Loeb 2010
UK-SKA &
Birmingham
2014
Reionization!
ends
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
More than reionization
!
• 21 cm fluctuations contain wealth of information!
- Lyman alpha fluctuations => star formation rate and first galaxies!
- Temperature fluctuations => X-ray sources and first black holes!
- Neutral fraction fluctuations => topology of reionization!
- Density fluctuations => cosmology
Brightness [mK]
Dark!
Ages
First galaxies
Reionization!
begins
Dark Ages
Heating begins
50
Pritchard
Loeb 2010
UK-SKA &
Birmingham
2014
Reionization!
ends
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
More than reionization
!
• 21 cm fluctuations contain wealth of information!
- Lyman alpha fluctuations => star formation rate and first galaxies!
- Temperature fluctuations => X-ray sources and first black holes!
- Neutral fraction fluctuations => topology of reionization!
- Density fluctuations => cosmology
Brightness [mK]
Dark!
Ages
Cosmic!
Dawn
First galaxies
Reionization!
begins
Dark Ages
Heating begins
50
Pritchard
Loeb 2010
UK-SKA &
Birmingham
2014
Reionization!
ends
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
More than reionization
!
• 21 cm fluctuations contain wealth of information!
- Lyman alpha fluctuations => star formation rate and first galaxies!
- Temperature fluctuations => X-ray sources and first black holes!
- Neutral fraction fluctuations => topology of reionization!
- Density fluctuations => cosmology
Brightness [mK]
Dark!
Ages
Cosmic!
Dawn
Reionization
First galaxies
Reionization!
begins
Dark Ages
Heating begins
50
Pritchard
Loeb 2010
UK-SKA &
Birmingham
2014
Reionization!
ends
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
Time evolution of signal
1 cMpc ~ 1deg
SKA FOV~ 20deg2
Santos+ 2008
UK-SKA Birmingham 2014
Jonathan Pritchard
Time evolution of signal
1 cMpc ~ 1deg
SKA FOV~ 20deg2
Santos+ 2008
UK-SKA Birmingham 2014
Jonathan Pritchard
STScI
MAR
2009
SKA
will
image
reionization
Simulation + Lya +X-rays
25
SKA will be first instrument with sensitivity for imaging!
Mellema+ 2013
=> map topology of reionization
~1deg
10’
Numerical simulations of baryons
+ dark matter with radiative
transfer needed for reionization
1’
Iliev+ 2014
- Baek+ 2008, 2010
Santos, Amblard, Pritchard+ 2008
UK-SKA Birmingham 2014
Fast approximate schemes being
developed:!
- Santos+ 2009
“Fast21CM”!
- Mesinger+ 2010 “21cmFast”!
- Thomas+ 2010
“BEARS”
Detailed numerical simulation
including spin temperature Lya & T fluctuations
needed:!
-can
Baek+be
2008,
2010
important
Jonathan Pritchard
Evolution of the power spectrum
Mesinger+ 2010
10 mK
1 mK
~10’
Measure power spectrum from z=27 to z~6 !
=>traces onset of star formation and IGM heating
UK-SKA Birmingham 2014
Jonathan Pritchard
Evolution of the power spectrum
Mesinger+ 2010
10 mK
1 mK
~10’
Measure power spectrum from z=27 to z~6 !
=>traces onset of star formation and IGM heating
UK-SKA Birmingham 2014
Jonathan Pritchard
First galaxies
Pop II vs Pop III stars - onset of metal enrichment!
!
Sterilisation of H2 channel with Lyman-Werner photons!
!
Sinks of ionising radiation!
!
Star formation rate - Lyman alpha production!
!
Black holes - X-ray emission
Complementarity with other observations e.g. HST, JWST, LAEs, ALMA + SKA => galaxies and IGM
UK-SKA Birmingham 2014
Jonathan Pritchard
z = 19.58
z = 22.67
z = 31.73
How the wind blows?
MH-1-NOREL
MH-2-NOREL
MH-1-REL
MH-3-NOREL
MH-2-REL
Recombination leads to sudden drop in sound speed
=> coherent supersonic relative motion of baryons and dark matter
cal Journal, 736:147 (5pp), 2011 August 1
No-rel: galaxy forms at z~20
MH-1-NOREL
z Rel:
= 19.58
snapshot at z~20
MH-2-NOREL
MH-1-REL
MH-3-REL
Tseliakhovich !
& Hirata 2010
Galaxy formation in low
mass z = 31.73
<108 Msol halos delayed
MH-3-REL
MH-2-REL
MH-3-REL
Greif et al.
zRel:
= z22.67
z
=
=gal19.58
z31.73
= 22.67
formation delayed to z~16
MH-3-NOREL
MH-2-REL
MH-1-REL
Little effect on high mass halos
=> importance of effect decreases at late times
z = 19.58
z = z22.67
= 19.58
z = z31.73
= z22.67
= 15.65
MH-1-REL
MH-2-REL
MH-1-REL
MH-3-REL
MH-2-REL
flow
Maio+2010, Greif+2011, z = z31.73
= 19.48
Stacey+2011 z = 26.06
Greif+ 2011MH-3-REL
T [K]
Side Length: 10 kpc (comoving)
10
360
300
20
240
0
180
z = 19.58
120
MH-1-REL
60
−20
z = z22.67
= 15.65
−40
MH-2-REL
Tb
1000
Coherence of velocity field leads
to boost in 21cm fluctuations!
=> much more detectable signal + enhanced BAO signature
Figure 1. Comparison of three statistically independent minihalos with no streaming velocity (top panels), and with an initial str
40
at z = 99 from left to right (middle and bottom
panels). We show the density-squared weighted gas temperature projected along
300
density in the center has just exceeded nH = 20
109 cm−3 (top and bottom panels), and when the streaming case has evolved to the sa
(middle panels). In the presence of streaming velocities, the effective Jeans mass of the gas is increased. The underlying DM ha
240
before the gas can cool, which delays the onset
of collapse. We also find that virial shocks are more pronounced in the direction
0
in other directions. Nonlinear effects of this sort maybresult in a higher velocity dispersion of the gas (see also Figure 4).
180
(A color version of this figure is available in −20
the online journal.)
z = z31.73
=
19.48
z = 26.06
120
360
40
100
T
−40
greater than 1.5MH-3-REL
km s−1 at z = 99, −60
which we consider
forms a Pop III star. We set Mmax
T [K] a lower
limit 10
forkpcthe
above delay to be significant, may
results are not sensititive to this pa
Side Length:
(comoving)
√ be found by
60
120
180
240
300
360
60
120
240
300
360
10
1000 are rare. As shown in Figure 5, t
infinity,
integrating
the 180
above
function
from
σ/2 = σ1d 1003/2 tostar
formation
inform
low
mass
cool
and
stars
is reduced by u
which
yields
approximately
0.86.
This
shows
that
our
results
z=20
With
vstreaming velocity (top panels), and with an initial streaming
Figure 1. v
Comparison of three statistically independentWithout
minihalos with no
velocity of 3 km s−1 applied
theline
presence
streaming
velocitie
maypanels).
be considered
representative
most gas
of the
volumeprojected
of
the along the
at z = 99 from left to right (middle and bottom
We show the
density-squaredfor
weighted
temperature
of sight of
when
the hydrogen
halos
important
Visbal+ 2012
Figure
3:
The
21-cm
brightness
temperature.
that
streaming
velocities should
be
density in the center has just exceeded nH =universe.
109 cm−3 (top and bottom panels), and when the streaming case has evolved to the same
redshift
as the no-streaming
case
(middle panels). In the presence of streaming The
velocities,
the effective Jeans
mass ofdensity
the gas isof
increased.
The underlying
therefore becomes
morestars
massive
influence
of the first
on obser
cosmological
number
minihalos
hosting DM halo
UK-SKA Birmingham
2014
Jonathan
Pritchard
−60
60
IF
before the gas can cool, which delays the onset of collapse. We also find that virial shocks are more pronounced in the direction of the incoming streaming flow than
Cosmology
SKA-LOW probes new !
volume of universe
Pritchard
To get cosmology must first
disentangle astrophysics
Cosmology requires some degree
of inventiveness:!
1) Infer density field directly (avoid + model astro, RSD)!
2) Heating driven by exotic sources
(DM annihilation,primordial BH, ...)!
3) Impact of cosmology on sources !
(non-Gaussianity, WDM, ...)!
4) Weak lensing (map DM)!
5) Other …!
UK-SKA Birmingham 2014
Jonathan Pritchard
120
ergs s!1 Hz!1. The depression
sponding to P151 ¼ 2:5 $
in the continuum due to absorption by the diffuse IGM is
much less evident than at higher redshift, with a mean value
of ! & 0:1%. The deep narrow lines are still easily seen but,
again, at lower redshift density than is found at higher
redshifts.
1035
High resolution studies of IGM
Fig. 4.—Radio spectrum of the powerful radio galaxy Cygnus A at
z ¼ 0:057 (P151 ¼ 1:1 $ 1036 ergs s!1 Hz!1; Baars et al. 1977). The dashed
line is a first-order polynomial fit to the (log) data, corresponding to a
power law of index !1:05 " 0:03. The solid line is a second-order polynomial fit.
21 cm forest: HI absorption to radio bright source
3.4. Limits to Detection
Traces cosmic web and structure of halos with
~kpc resolution
sponds to a first-order polynomial fit to the data in the log
plane, corresponding to a power law of index !1:05 " 0:03.
The dashed line corresponds to a second-order polynomial.
We use this second-order polynomial in the analysis below.
Radio bright QSO at z>7?
reionization
We next consider the detection limit of the absorption signal using statistical tests. The challenge is greater at lower
redshifts because of the decreasing strength and redshift
z=7 QSO
Mortlock+2011
z>7 QSO with Euclid
never r
esonan
t
HI abso
rption
cosmic
simulated!
20 mJy QSO!
at z=10
Carilli+2002
web
halos
Fig. 5a
Fig. 5b
Fig.
5.—(a) Simulated
spectrum
from 100 to 200 MHz of a source with S120 ¼ 20 mJy at z ¼ 10 using the Cygnus A spectral model and assuming
H i 21 cm
UK-SKA
Birmingham
2014
Jonathan
Pritchard
Foreground removal
Foregrounds ~ 103 signal
&+D
Foreground removal challenging, but exploiting spectral smoothness of foregrounds seems effective !
Various techniques e.g. ICA, GMCA, … Chapman+ 2013
UK-SKA Birmingham 2014
Jonathan Pritchard
Instrumental path to detection
PAPER
MWA
SKA-LOW
LOFAR
HERA
(2015-2020)
Fig. 5.— The MWA (top left) and PAPER (bottom left) arrays, each currently deployed with 128 elements.
PAPER/MWA setting upper limits <(50mK)2 compared with signal ~(few mK)2!
The 14-m HERA element (right) dramatically improves sensitivity while still delivering the spectral smoothness and stability of response that are required for managing foregrounds. The core of HERA 568 consists
of a redundant hexagonal array with outrigger antennas (not shown) for imaging and foreground mitigation.
Sensitivity required for detection almost achieved (LOFAR ~100hrs analysed ~600hrs collected)!
imaging (MWA). Together, these advances enable HERA to achieve the science goals envisioned in
the decadal survey at a fraction of the anticipated cost.
HERA follows a staged deployment in both physical construction and scientific processing. In
each deployment stage, improvements are incorporated into the system and new science capabilities
are unlocked. This approach o↵ers two advantages: providing early access to science, and reducing
the project risk by testing systems early and changing them incrementally. As shown in Figure
2, each stage of HERA brings an associated improvement in sensitivity that allows key aspects of
21-cm reionization science to be addressed. The timeline of HERA development and its associated
science products is outlined below.
Year 1–Infrastructure and First 37 Antennas (FY 2015).
• Install basic infrastructure (ground leveling, power, network connectivity) at a new site
⇠10 km from the current PAPER site in the Karoo.
• Move existing PAPER-128 antennas, correlator, and EMC container to new site.
• Install first 37 HERA antennas with existing PAPER feeds, electronics, and correlator.
• Start developing improved HERA baluns, receivers, feeds, nodes, and in-situ antenna calibration system. Continue delay-spectrum, FHD, and optimal estimator software development.
Year 2–Hardware Commissioning and Deep Foreground Survey (FY 2016).
• Commissioning observations using a hybrid array of 37 HERA antennas in a close-packed
hexagon surrounded by 91 PAPER antennas in an imaging configuration.
• Perform a polarized foreground survey using hybrid-antenna capability of FHD. Determine
on-sky beam response of HERA antennas to facilitate future source subtraction e↵orts.
• Finalize site infrastructure (high-bandwidth optical network, surveying, trenching).
• Commission new feeds, receivers, nodes, and calibration systems in Green Bank and SA.
• Begin HERA 127 construction.
Year 3–HERA 127 and Detecting the Rise and Fall of Reionization (FY 2017).
• Complete HERA 127 construction. Science observations begin using the PAPER correlator.
• Apply proven delay-spectrum analysis techniques to HERA 127 observations to constrain the
timing and duration of reionization.
Each step in sensitivity pushes ability to remove foregrounds & control instrumental systematics
k3P(k)/2π2 [mK2]
current observations
21cm signal
PAPER
MWA
LOFAR
SKA
tint=1000hours
k[Mpc-1]
Mellema+ 2013
MWA-32T: Dillon+ 2013; GMRT: Paciga+ 2013; PAPER-32: Parsons+ 2013; LOFAR: Yatawatta+ 2013
UK-SKA Birmingham 2014
Jonathan Pritchard
a
cting area Atot , bandwidth B, and total integration time tint for each instrument. These values are fixed
=?? and extrapolated to other frequencies using Atot = Nant Ndip Adip with the number of antennae per
on Ndip = 289 and Adip = min(l 2 /3, 3.2 m2 ).
Story of Universe is story of hydrogen
Array
MWA
LOFAR Core
HERA
SKA0
SKA1
SKA2
Na
112
48
331
850⇥0.5
850
850⇥4
Atot (103 m2 )
1.6
38.6
50.0
290⇥0.5
290
290⇥4
B (MHz)
8
8
8
8
8
8
tint (hr)
1000
1000
1000
1000
1000
1000
Rmin (m)
4
100
14.3
35
35
35
Rmax (km)
0.75
1.5
0.3
2
2
2
SKA-LOW Phase 1
~10 more collecting area!
than LOFAR
~10 number of stations
Brightness [mK]
We first illustrate the sensitivity of different iterations of SKA in Figure 2, where we take the
meters in Table 1 for SKA0 - with 50% of the SKA1 baseline collecting area, SKA1, and
A2 - with x4 the collecting area of SKA1. For each of these we assume a filled core followed
2 distribution out to a maximum radius R
max . HERA is assumed to have a uniform antennae
ibution. SKA1 has 911 stations total with 899 in the core and 650 stations within a radius
km accounting for 75% of the total number of stations and collecting area. We limit to the
rmost 850 within 2km, as the outer stations add little to the sensitivity. Physical station size is
. Stations have 289 antennae with antennae area Ae = l 2 /3 giving 3.2m2 at 110MHz. At lower
Firstand
galaxies
uencies the array is densely packed
has constant collecting area, at higher frequencies the
y becomes sparse.
Reionization!
Figure 2 illustrates a few key points governing parameter constraints.
Here we have eliminated
es whose wavelength exceeds the instrument bandwidth removingbegins
sensitivity to the largest
Dark Ages
ical scales (smallest k modes). At z = 8, SKA0 is directly comparable in sensitivity to the
osed HERA experiment [2], which is more centrally concentrated to compensate for its small
Heating begins
50
Pritchard
Loeb 2010
UK-SKA&Birmingham
2014
Reionization!
ends
4
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
a
cting area Atot , bandwidth B, and total integration time tint for each instrument. These values are fixed
=?? and extrapolated to other frequencies using Atot = Nant Ndip Adip with the number of antennae per
on Ndip = 289 and Adip = min(l 2 /3, 3.2 m2 ).
Story of Universe is story of hydrogen
Array
MWA
LOFAR Core
HERA
SKA0
SKA1
SKA2
Na
112
48
331
850⇥0.5
850
850⇥4
Atot (103 m2 )
1.6
38.6
50.0
290⇥0.5
290
290⇥4
B (MHz)
8
8
8
8
8
8
tint (hr)
1000
1000
1000
1000
1000
1000
Rmin (m)
4
100
14.3
35
35
35
Rmax (km)
0.75
1.5
0.3
2
2
2
SKA-LOW Phase 1
~10 more collecting area!
than LOFAR
~10 number of stations
We first illustrate the sensitivity of different iterations of SKA in Figure 2, where we take the
meters in Table 1 for SKA0 - with 50% of the SKA1 baseline collecting area, SKA1, and
A2 - with x4 the collecting area of SKA1. For each of these we assume a filled core followed
2 distribution out to a maximum radius R
max . HERA is assumed to have a uniform antennae
ibution. SKA1 has 911 stations total with 899 in the core and 650 stations within a radius
km accounting for 75% of the total number of stations and collecting area. We limit to the
rmost 850 within 2km, as the outer stations add little to the sensitivity. Physical station size is
. Stations have 289 antennae with antennae area Ae = l 2 /3 giving 3.2m2 at 110MHz. At lower
Firstand
galaxies
uencies the array is densely packed
has constant collecting area, at higher frequencies the
y becomes sparse.
Reionization!
Figure 2 illustrates a few key points governing parameter constraints.
Here we have eliminated
es whose wavelength exceeds the instrument bandwidth removingbegins
sensitivity to the largest
Dark Ages
ical scales (smallest k modes). At z = 8, SKA0 is directly comparable in sensitivity to the
osed HERA experiment [2], which is more centrally concentrated to compensate for its small
Brightness [mK]
HERA
GMRT
Reionization!
ends
Heating begins
50
Pritchard
Loeb 2010
UK-SKA&Birmingham
2014
MWA
LOFAR
PAPER
4
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
a
cting area Atot , bandwidth B, and total integration time tint for each instrument. These values are fixed
=?? and extrapolated to other frequencies using Atot = Nant Ndip Adip with the number of antennae per
on Ndip = 289 and Adip = min(l 2 /3, 3.2 m2 ).
Story of Universe is story of hydrogen
Array
MWA
LOFAR Core
HERA
SKA0
SKA1
SKA2
Na
112
48
331
850⇥0.5
850
850⇥4
Atot (103 m2 )
1.6
38.6
50.0
290⇥0.5
290
290⇥4
B (MHz)
8
8
8
8
8
8
tint (hr)
1000
1000
1000
1000
1000
1000
Rmin (m)
4
100
14.3
35
35
35
Rmax (km)
0.75
1.5
0.3
2
2
2
SKA-LOW Phase 1
~10 more collecting area!
than LOFAR
~10 number of stations
We first illustrate the sensitivity of different iterations of SKA in Figure 2, where we take the
meters in Table 1 for SKA0 - with 50% of the SKA1 baseline collecting area, SKA1, and
A2 - with x4 the collecting area of SKA1. For each of these we assume a filled core followed
2 distribution out to a maximum radius R
max . HERA is assumed to have a uniform antennae
ibution. SKA1 has 911 stations total with 899 in the core and 650 stations within a radius
km accounting for 75% of the total number of stations and collecting area. We limit to the
rmost 850 within 2km, as the outer stations add little to the sensitivity. Physical station size is
. Stations have 289 antennae with antennae area Ae = l 2 /3 giving 3.2m2 at 110MHz. At lower
Firstand
galaxies
uencies the array is densely packed
has constant collecting area, at higher frequencies the
y becomes sparse.
Reionization!
Figure 2 illustrates a few key points governing parameter constraints.
Here we have eliminated
es whose wavelength exceeds the instrument bandwidth removingbegins
sensitivity to the largest
Dark Ages
ical scales (smallest k modes). At z = 8, SKA0 is directly comparable in sensitivity to the
osed HERA experiment [2], which is more centrally concentrated to compensate for its small
Brightness [mK]
SKA
GMRT
Reionization!
ends
Heating begins
50
Pritchard
Loeb 2010
UK-SKA&Birmingham
2014
HERA
MWA
LOFAR
PAPER
4
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
a
cting area Atot , bandwidth B, and total integration time tint for each instrument. These values are fixed
=?? and extrapolated to other frequencies using Atot = Nant Ndip Adip with the number of antennae per
on Ndip = 289 and Adip = min(l 2 /3, 3.2 m2 ).
Story of Universe is story of hydrogen
Array
MWA
LOFAR Core
HERA
SKA0
SKA1
SKA2
Na
112
48
331
850⇥0.5
850
850⇥4
Atot (103 m2 )
1.6
38.6
50.0
290⇥0.5
290
290⇥4
B (MHz)
8
8
8
8
8
8
tint (hr)
1000
1000
1000
1000
1000
1000
Rmin (m)
4
100
14.3
35
35
35
Rmax (km)
0.75
1.5
0.3
2
2
2
SKA-LOW Phase 1
~10 more collecting area!
than LOFAR
~10 number of stations
We first illustrate the sensitivity of different iterations of SKA in Figure 2, where we take the
meters in Table 1 for SKA0 - with 50% of the SKA1 baseline collecting area, SKA1, and
A2 - with x4 the collecting area of SKA1. For each of these we assume a filled core followed
2 distribution out to a maximum radius R
max . HERA is assumed to have a uniform antennae
ibution. SKA1 has 911 stations total with 899 in the core and 650 stations within a radius
km accounting for 75% of the total number of stations and collecting area. We limit to the
rmost 850 within 2km, as the outer stations add little to the sensitivity. Physical station size is
. Stations have 289 antennae with antennae area Ae = l 2 /3 giving 3.2m2 at 110MHz. At lower
Firstand
galaxies
uencies the array is densely packed
has constant collecting area, at higher frequencies the
y becomes sparse.
Reionization!
Figure 2 illustrates a few key points governing parameter constraints.
Here we have eliminated
es whose wavelength exceeds the instrument bandwidth removingbegins
sensitivity to the largest
Dark Ages
ical scales (smallest k modes). At z = 8, SKA0 is directly comparable in sensitivity to the
osed HERA experiment [2], which is more centrally concentrated to compensate for its small
Brightness [mK]
LUNAR!
ARRAY
SKA
GMRT
Reionization!
ends
Heating begins
50
Pritchard
Loeb 2010
UK-SKA&Birmingham
2014
HERA
MWA
LOFAR
PAPER
4
100
Frequency [MHz]
150
200
⌫ = 1420MHz/(1
+ z)
Jonathan Pritchard
Key science with SKA
•
•
SKA will help complete our understanding of cosmic history!
•
21cm fluctuations from z=27 to z=6 traces evolution of first
galaxies and x-ray sources!
•
•
Test cosmology with bulk flows at z>20!
•
•
High resolution IGM studies with 21cm forest!
SKA will image ionised regions directly mapping out
topology of reionization!
Cosmology and fundamental physics from lensing, thermal
history, and density fluctuations!
Complements UK strengths in high-z galaxy observations,
galaxy formation simulation, CMB analysis, …
See Mellema+ 2013 (arXiv:1210.0197) and upcoming SKA Science Case
UK-SKA Birmingham 2014
Jonathan Pritchard