Evolution of radio telescopes (Braun 1996)
-
Upload
orlando-wolf -
Category
Documents
-
view
15 -
download
0
description
Transcript of Evolution of radio telescopes (Braun 1996)
Evolution of radio telescopes (Braun 1996)
SKA in context
Fields of View
Centimeter observations of thermal sources at mas resolution
X NGC1068 Disk
X PP-disks
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)
SKA Designs ("compliance" matrix)http://www-astro.physics.ox.ac.uk/~sr/ska/ska_matrix.html
Level 1 Science Strawman China Europe India Ozlens Ozcyli USA Canada
1: Galactic HI YES UPGRADE? UPGRADE? YES YES YES UPGRADE? UPGRADE?
1: Galactic NT+B YES UPGRADE? NO YES UPGRADE? YES YES UPGRADE?
2: Transients UPGRADE? NO NO NO NO NO NO NO
2: Pulsars UPGRADE? NO NO NO NO NO NO NO
2: SETI UPGRADE? NO NO NO NO NO NO NO
3: EOR UPGRADE? NO UPGRADE? UPGRADE? UPGRADE? UPGRADE? UPGRADE? UPGRADE?
4: HI surveys / LSS YES UPGRADE? UPGRADE? YES YES YES YES YES
4: Continuum surveys
UPGRADE? NO NO UPGRADE? UPGRADE? UPGRADE? UPGRADE? UPGRADE?
4: CO surveys YES NO NO UPGRADE? NO UPGRADE? YES YES
5: Hi-z AGN UPGRADE? NO NO YES UPGRADE? YES YES UPGRADE?
5: Inner AGN UPGRADE? NO NO UPGRADE? NO UPGRADE? YES UPGRADE?
6: Protoplanetary systems
UPGRADE? NO NO UPGRADE? NO UPGRADE? YES YES
7: CMEs UPGRADE? NO UPGRADE? UPGRADE? YES YES UPGRADE? YES
7: SS bodies YES NO NO UPGRADE? NO UPGRADE? UPGRADE? YES
8: IGM non thermal YES UPGRADE? NO YES YES YES UPGRADE? UPGRADE?
8: IGM thermal UPGRADE? NO NO UPGRADE? NO NO YES UPGRADE?
9: Spacecraft Tracking
UPGRADE? NO NO UPGRADE? NO NO YES UPGRADE?
9: Geodesy UPGRADE? NO NO UPGRADE? NO UPGRADE? UPGRADE? UPGRADE?
Notes: Level-1 science may still be missing. 'Level-1' probably not a uniform measure across the WGs.
Last updated: 10th August 2002
Compliance Matrix: www-astro.physics.ox.ac.uk/~sr/ska/ska_matrix.html
Highest z HI emission to date: 110 hours VLA + GMRT
Verheijen, Dwarakanath, van Gorkom
kpc60Dkpc120DM101M(HI) optHIsun10
SMC
M 101
M 51
Maximum redshift for a 360 hour integration with SKA
Star formation with z
Crucial epoch
2000 galaxies/ deg
100 000
30 000
z = 2 z = 4
z = 0.45
z = 0.9
M101 z = 0.2
Imaging to z=1 => TF distances => peculiar motions
Braun 1996
SKA HI Survey: ‘Sloan x 100’
1000 hrs, 1000 sq.deg.
Evolution of gas and dark matter content of galaxies
Origin of Hubble sequence and density-morphology relation
Evolution of LSS and cluster velocity dispersions
Tully-Fisher distances: Peculiar motions => evolution of bias parameter
SKA continuum survey: HDFx10000
5e8 sources at > 0.3 uJy over 1000 sq.deg.
Star formation history of the universe unbiased by dust
Massive black hole formation and accretion history
Hopkins 1999
Dust obscured star formation at high z:
The brightest mm source in HDF not detected by HST!
Elliptical galaxy formation in dusty, high z starbursts?
Maximum redshift for a 360 hour integration with SKA
resolved flux (0.1”) total flux (1”)
M 33
NGC 6946
resolved flux total fluxM 51
Thermal flux
HI 21cm absorption in deep, wide surveys
1229-021 Briggs 1996
z_abs = 0.4
N(S>1mJy) = 36000 => O(50000) HI 21cm absorption lines by damped
Ly alpha systems (1e20 /cm/cm, T_spin = 1000 K)
Dense ISM in nascent galaxies
Dust unbiased QSO statistics: ‘Red quasars’ and ‘dark’ gravitational lenses
Evolution of physical constants
OH megamasers in deep HI surveys: beacons to high z, merging starburst galaxies
Briggs 1995
Highest z CO emission to date: 24 hrs/source w. VLA M(H_2) = few e11 M_sun
1202-0725 z =4.69
CO(2-1)
2322+1944 z = 4.12
CO(2-1)
1331-0417 z = 4.41
CO(2-1)
0827+5255 z = 3.91
CO(1-0)
0827+5255 at z=3.9: An ‘Einstein Arc’ in CO
8 GHz
HST
CO(2-1)
300 pc
SKA and CO
22 GHz
43 GHz
M(H_2) = few e9 M_sun
Optimal CO surveys: ‘speed of discovery’
Carilli and Blain 2002
HCN (89 GHz): Dense gas + starburst tracer?
Solomon 2001
Conflict I: low vs. high frequency?
HI Surveys require frequencies < 1.4 GHz
CO Surveys require frequencies > 20 GHz
Can we do both with one design?
Epoch of Reionization:
Evolution of the neutral IGM (Gnedin): ‘Cosmic Phase transition’
HI fraction
density Gas Temp
Ionizing intensity
Gunn-Peterson effect
Barkana and Loeb 2001
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
Briggs
Upper limit to z_reio: CMB anisotropies
Studying the IGM beyond the EOR: HI 21cm observations with the Square Kilometer Array and LOFAR
_21cm = 1e-8 _Lya
Temperatures: 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
HI 21cm Emission
Difficulty with (LSS) emission observations: confusion by foreground radio sources (di Matteo 2001)
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 = 10 z = 8
SKA observations of absorption before the EOR
A/T = 2000 m^2/K 240 hrs 1 kHz/channel
Radio sources beyond the EOR?
0924-220 z = 5.19 S_151 = 600 mJy
0913+5821 z = 5.12 S_151 = 150 mJy
1”
Inverse Compton losses off the CMB
= U_B (radio lobe)
Radio sources beyond the EOR:
sifting problem (1/1400 per 20 sq.deg.)
2240 at z > 6
1.4e5 at z > 6
USS samples (de Breuck et al.)
Conflict II: Long vs. Short baselines?
EOR emission requires arcmin resolution => baselines < 5km
EOR absorption requires arcsec resolution => baselines > 300km
Both are sensitivity limited: where to put our collecting area?