Transcript The Transient Radio Sky Astrophysical and Artificial

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
China KARST
Canada LAR
US LargeN+Small-D
Australia
Luneburg
Lenses
Europe:
phased array
Australia:
Cylindrical
Telescopes
India:
Preloaded
parabolas
•“White Papers” issued
for each concept in 2002
•Reviewed by EMT/ISAC
and revised 2003
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
Advantages: many simultaneous beams, fast response
Disadvantage: Max. frequency = 1.4 GHz
SKA poster (multi-beams)
Disadvantage: max freq = 1.4 GHz
SKA and VLBI
“SKV”
The SKV – Scaled arrays to 5000 km
Centimeter observations of thermal sources at mas resolution
X PP-disks
X NGC1068 Disk
SKV
+
SKV Science
• Dust obscured star and black hole formation history
a. starburst – AGN connection/discrimination:
T_B(5s,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
SKV Science
•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
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
Ionizing
intensity
density
Gas
Temp
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, mJy 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
30 Mpc comoving
QSOs: 3uJy/beam at 2’ res
With and without soft Xray
pre-heating.
Difficulty with (LSS) emission observations: Confusion
Continuum sources (di
Free-Free emission (Oh
Matteo et al.2002)
& Mack 2002)
Cosmic Web after reionization = Ly alpha forest (d <= 10)
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 before reionization: HI 21cm Forest
Z=9
Z=7
Carilli, Gnedin,
Owen 2002
  0.008(
TCMB 1  z 1/ 2
)(
) f HI (1  d )
TS
10
Absorption – best done
at (sub)arcsecond
resolution => 1000 km
baselines
•Mean optical depth (z = 10) = 1% = ‘Radio Gunn-Peterson effect’
•Narrow lines (1 to 10%, few km/s) = HI 21cm forest (d = 10)
SKA observations of absorption before the EOR
A/T = 2000 m^2/K
z = 10
240 hrs 1 kHz/channel
z=8
Absorption in primordial disks toward GRBs/Starbursts?
N/Dz << 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?
>1
Furlanetto & Loeb 2002
Radio sources beyond the EOR?
Luminous radio sources at very high z
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
M_BH = 1e9 M_sun
10mas
1”
•(sub)arcsec resolution preferred: decrease confusion,
allow imaging
CO 3-2 at z=6.42
1148+5251 z=6.42
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
46.6 GHz
Radio sources beyond the EOR:
sifting problem (1/1400 per 20 sq.deg.)
1.4e5 at z > 6
S_120 > 6mJy
2240 at z > 6
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 1mm
•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.
final design and site choice by ISSC in 2007
Goal:
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 l_obs < 1 mm
Lower limit to z_reio: GP Effect
White et al. 2003
f(HI) > 0.01 at z = 6.3
Fan et al. 2002
Upper limit to z_reio: CMB anisotropies
Briggs
Thompson scattering => polarization
•Large scale
structure (10’s deg)
=> relic of EOR
•  = Ln_es_e = 0.17
=> z_reion = 10 to 20
(Kogut et al. 2003)
f(HI) < 0.5 at z = 20
f(HI) > 0.01 at zKogut
= 6.3 et al. WMAP
IGM Thermal History: Spin, CMB, Kinetic and the 21cm
signal
Tozzi 2002
T_s
T_CMB
T_K
•Initially T_S= T_CMB
•T_S = T_CMB => no signal
•T_S couples to T_K via Lya scattering
•T_S = T_K < T_CMB => Absorption
against CMB
•T_K = 0.026 (1+z)^2 (wo. heating)
•T_CMB = 2.73 (1+z)
•T_S > T_CMB => Emission
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 (d > 100) (Furlanetto & Loeb
2002)
N/Dz(minihalos) = N/Dz(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?