SKA in context

z=8

Fields of View

1deg^2 With Full Sensitivity at subarcsec resolution

RMS sensitivity in 8hrs at 1.4 GHz = 23 nJy

•“White Papers” issued for each concept in 2002•Reviewed by EMT/ISAC and revised 2003

China KARSTChina KARST

Canada LARCanada LAR

US Large-US Large-N+Small-DN+Small-D

Australia Australia Luneburg Luneburg LensesLenses

Europe: Europe: phased arrayphased array

Australia:CylindricalTelescopes

India:Preloadedparabolas

Concept USA: ‘Nd’

•4640 x 12m parabolic antennas

•Full Xcorr inner 2300 ants (35 km), outer ‘stations’ of 13 ants

•Advantage: works to high frequency (> 20 GHz)

•Disadvantage: no ‘full-sky, full-array’ multibeaming

Concept Euro: nD – Phased arrays

SKA poster (multi-beams)

Advantages: many simultaneous beams, fast responseDisadvantage: Max. frequency = 1.4 GHz

Disadvantage: max freq = 1.4 GHz

“SKV”

SKA and VLBI

The SKV – Scaled arrays to 5000 km

Centimeter observations of thermal sources at mas resolution

X NGC1068 Disk

X PP-disks

+SKV

SKV Science• Dust obscured star and black hole formation history

a. starburst – AGN connection/discrimination: T_B(5,8hrs,20mas,1.4GHz)=200K (SSCs, EG HII, SNR,… imaging to z=0.5)

b. counting RSNe to z = 3, imaging expansion to z=0.05

c. mapping OH megamasers to z = 0.3

• Imaging water maser disks to z=0.06

• Imaging (faint) GRBs

•High redshift radio absorption lines (HI, molecular): probing dense ISM, evolution physical constants

•(SM)BH physics: low luminosity AGN -- Jet/accretion disk connection, XDAFs, Extragalactic microQuasars

•Protoplanetary disks, jets, and planets: imaging thermal emission at subAU scales, astrometry – Jovian planets around non-flaring solar-type stars to 50pc (30,000 stars!), Jupiter bursts to 100 pc.

•Solar-Stellar connection: imaging coronal activity to 5pc (30 stars)

•Extragalactic pulsars/stellar masers – proper motions

•Geodesy – millimeter accuracy => Earth quake prediction?

•Scattering and Scintillation – uas astronomy, turbulent ISM/IPM

SKV Science

•Proper motions of low luminosity AGN to Virgo – ‘mass map’ of the local supercluster

•Epoch of Reionization – 21cm absorption by neutral IGM toward 1st radio loud AGN/GRBs/Star forming galaxies

For more details see: http://www.euska.org/workshops/hr_ws_MPIfR_Bonn.html

SKV Science

Epoch of Reionization End of ‘Dark age’ sets the fundamental benchmark for cosmic structure formation – formation first luminous objects

Evolution of the neutral IGM (Gnedin): ‘Cosmic Phase transition’

HI fraction

density Gas Temp

Ionizing intensity

Discovery of the EoR

Gunn-Peterson Absorption => f(HI) > 0.01 at z=6.3 (Fan et al. 2002)

CMB large scale (>10deg) polarization => f(HI) < 0.5 at z=17 (Kogut et al. 2003)

Studying the pristine IGM beyond the EOR: HI 21cm observations with the SKA and LOFAR

SKA: A/T = 20000 m^2/K => nJy sensitivity at 1.4 GHz, Jy at 200 MHz

Freq range = 0.1 to 20 GHz

Resolution = 0.1” at 1.4GHz

Imaging the neutral IGM at z=8.5 (Tozzi 2002)

Galaxies: 6uJy at 2’ res

(= 20 mK)

tCDM and OCDM

QSOs: 3uJy/beam at 2’ res

With and without soft Xray pre-heating.

30 Mpc comoving

Difficulty with (LSS) emission observations: Confusion

Continuum sources (di Matteo et al.2002)

Free-Free emission (Oh & Mack 2002)

1422+23 z=3.62 Womble 1996

N(HI) = 1e13 -- 1e15 cm^-2, f(HI/HII) = 1e-5 -- 1e-6

=> Before reionization N(HI) =1e18 – 1e21 cm^-2

Cosmic Web after reionization = Ly alpha forest ( <= 10)

Cosmic Web before reionization: HI 21cm Forest

)1()10

1)((008.0 2/1

HI

S

CMB fz

T

T

•Mean optical depth (z = 10) = 1% = ‘Radio Gunn-Peterson effect’

•Narrow lines (1 to 10%, few km/s) = HI 21cm forest (= 10)

Carilli, Gnedin, Owen 2002

Z=9 Z=7

Absorption – best done at (sub)arcsecond resolution => 1000 km baselines

z = 10 z = 8

SKA observations of absorption before the EOR

A/T = 2000 m^2/K 240 hrs 1 kHz/channel

Absorption in primordial disks toward GRBs/Starbursts?

N/z << minihalos and IGM (<1e-4x) but

>> minihalos and IGM (>50x) => Use much fainter radio sources (0.1 mJy): GRB afterglow within disk? or Starburst radio emission?

Furlanetto & Loeb 2002

> 1

Radio sources beyond the EOR?

Radio galaxy: 0924-220 (van Breugel et al) z = 5.19 S_151 = 600 mJy

Quasar: 0913+5821 (Momjian et al.) z = 5.12 S_151 = 150 mJy

1”

Luminous radio sources at very high z

•(sub)arcsec resolution preferred: decrease confusion, allow imaging

M_BH = 1e9 M_sun10mas

VLA detection of CO 3-2 emission from most distant QSO – within the EoR (Walter, Carilli, Bertoldi)

M(dust) = 1e8 M_sun

M(H_2) = 2e10 M_sun

M_BH = 1 – 5e9 M_sun

M_dyn > 1e10 M_sun

S_190MHz = 0.1 mJy predicted if dust is heated by star formation

CO 3-2 at z=6.42

46.6 GHz1148+5251 z=6.42

Radio sources beyond the EOR:

sifting problem (1/1400 per 20 sq.deg.)

2240 at z > 6

1.4e5 at z > 6

S_120 > 6mJy

Summary: SKA study of the EoR

•‘Complex’ reionization -- GP: F(HI) > 0.01 at z=6.4, CMB pol: F(HI) < 0.5 at z= 20.

•Neutral IGM is opaque => need observations longward of 1m

•Neutral, pristine IGM: realm of low frequency radio astronomy.

•HI 21cm emission probes large scale structure.

•HI 21cm absorption probes intermediate to small scale structure (radio GP effect, ‘21cm forest’, minihalos, proto-disks) – (sub)arcsec resolution decreases confusion, allows imaging.

•Constrain: z_reion, detailed structure formation, nature of first luminous sources, ionizing background, IGM heating and cooling.

•LOFAR should provide first detections of the neutral IGM at z>6.

•SKA will allow for detailed studies.

ISSC: SKA planning schedule• 2002 Design concept “white papers” • 2002 Director Appointed: Management plan with ISSC• 2003 Updated design concept “white papers”• 2003 “White papers” on possible locations• 2004 Updated “white papers” on locations• 2005 Choice of SKA location• 2005 Full Proposals for designs to ISSC• 2007 SKA “facility definition” (may merge designs)• 2010-12 SKA construction begins ?• 2015-17 SKA completed ?

ISAC Mandates:

1. Revise science case and requirements, involving larger community, and put in context of future capabilities at other wavelengths. Goal: new Taylor-Braun document by Aug. 2004.

2. Evaluate (w. EMT) proposed SKA designs and advise ISSC. Goal: final design and site choice by ISSC in 2007

Current documentation:

1. Science with the Square Kilometer Array, R. Taylor & R. Braun, 1999 (www.skatelescope.org/ska_science.shtml)

2. Perspectives on Radio Astronomy: Science with Large Antenna Arrays, ed. M. van Haarlem, 1999 (ASTRON)

3. SKA memo series: Groningen (2002), Bologna (2002), and Berkeley(2001), science working group reports (www.skatelescope.org/ska_memos.shtml)

Discovery of the EOR (Becker et al. 2002)

Fast reionization at z = 6.3

=> opaque at _obs < 1 m

Fan et al. 2002

Lower limit to z_reio: GP Effect

f(HI) > 0.01 at z = 6.3

White et al. 2003

Briggs

Upper limit to z_reio: CMB anisotropies

Thompson scattering => polarization

•Large scale structure (10’s deg) => relic of EOR

• = Ln_ee = 0.17

=> z_reion = 10 to 20 (Kogut et al. 2003)

f(HI) < 0.5 at z = 20

Kogut et al. WMAPf(HI) > 0.01 at z = 6.3

IGM Thermal History: Spin, CMB, Kinetic and the 21cm signal

•Initially T_S= T_CMB

•T_S couples to T_K via Lya scattering

•T_K = 0.026 (1+z)^2 (wo. heating)

•T_CMB = 2.73 (1+z)

•T_S = T_CMB => no signal

•T_S = T_K < T_CMB => Absorption against CMB

•T_S > T_CMB => Emission

T_K

T_CMBT_s

Tozzi 2002

Evolution of <temperatures> in the simulation

Confusion by free-free emission during EOR

(Oh & Mack 2003)

Detection limits

Running rms: S_120 > 6 mJy in

240 hrs

KS of noise:

S_120 > 12mJy

Absorption by minihalos ( > 100) (Furlanetto & Loeb 2002)

N/z(minihalos) = N/z(IGM) = 10/unit z at z=8, > 0.02

Inverse Compton losses off the CMB

= U_B (radio lobe)

CDM structure formation (PS)

Efstathiou 1995

M_BH = 0.006 M_spheroid

N(1e11, z=6 – 8) = 3/arcmin^2

Evolution of space density of luminous QSOs (Fan et al. 2003)

USS samples (de Breuck et al.)

z>8 radio galaxies?