The Transient Universe: AY 250 Spring 2007 New Radio Telescopes Geoff Bower

The Transient Universe: AY 250 Spring 2007

New Radio Telescopes

Geoff Bower


State of the Art

• 27 antennas– 25 m in diameter– D_eff ~ 130m

• 400 cm to 0.7 cm wavelength

• 1- 35 km baselines• Resolution: 9 arcmin

to 40 milliarcsec

Very Large Array


State of the Art

• 10 antennas• 25 m in diameter• 90 cm --- 0.7 cm• Baselines 100 km ---

8000 km• Resolution: 20 to 0.2

milliarcsec

Very Long Baseline Array


Evolutionary Deadends


Na D (NaD^2)^2

(NaD)^2

VLA 27 25 2e8 5e5

ATA 350 6 2e8 4e6

GBT 1 100 1e8 1e4

Arecibo 1 200 2e9 4e4



Key Characteristics of Next Generation Telescopes

• Greater sensitivity

• More complete image sampling

• Broader wavelength coverage

• Rapid survey speed

• Multi-user capability Large N, Small DiameterLNSD


Cost OptimizationCost per Hectare

0.00

5.00

10.00

15.00

20.00

25.00

30.00

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

Primary Diameter (m)

M$

LaborDSPRF/IFTrenchF/O LinkFront EndAntenna

6.1 m

Cost ~ D^2.7


The Radio Revolution


Allen Telescope Array



Allen Telescope Array• Large N design

– 350 x 6.1m antennas– Sensitivity of the VLA– Unprecedented imaging capabilities

• Continuous frequency coverage– 0.5 to 11.2 GHz

• Wide field of view– 3.5 degrees at 1 GHz– Excellent survey instrument: 17x FOV of VLA

• Compact Configuration– 1 arcmin at 1.4 GHz (350), 1 arcmin at 5 GHz (42)

• Simultaneous observing with multiple backends– Correlator: 2 x 100 MHz x full Stokes x 1024 channels– Phased array beams: 32 indepent at 4 frequencies

• Joint project of UC Berkeley/SETI Inst.• Privately funded construction

– $26M from PGAF and others– NSF support for correlator & operations ($2.2M)– USNO support for construction ($3M)


ATA Log-Periodic Feed

Treceiver~35 K

TLNA~10 K

LNAs from Weinreb & Wadefalk

Feed by Welch & Engargiola

Gain of ATA Feed Antenna

-40

-30

-20

-10

0

10

20

0 2 4 6 8 10 12

GHz

dBi


The Antenna

• 6.1-m offset Gregorian• Low diffractive spillover

~1% at all elevations• Surface rms ~ 1mm• Works to 25 GHz


Antenna Configuration

1 km

Sidelobes less than 1%



ATA-42 Operational Soon

Movie 3x real time

4 deg/sec in azimuth, 2 deg/sec in elevation


Andromeda in a Single Pointing

• 7 antennas• 2 nights


ATA Science• SETI

– GC survey: 20 sq. deg, 1.4-1.7 GHz, 6 months

– 106 stars over 1-10 GHz• Arecibo radar detectable

at 300 pc– Simultaneous with correlator

• Extragalactic HI survey– Neutral gas SDSS equivalent– L* at z=0.1 over the entire sky

• Galactic magnetic fields, HI, long-chain molecules

• Pulsars• Radio continuum science

– All sky surveys– Transients (1 msec 1 year)

Robishaw, Simon & Blitz 2002

LGS

3


The EVLA

• Upgrade of the VLA• Bandwidth

– 100 MHz 8 GHz

• Correlator– 256 channels 256k

• Continuous frequency coverage– 1.0 to 50 GHz


EVLA Phase I - Key Science Examples

• Measuring the three-dimensional structure of the Sun's magnetic field • Mapping the changing structure of the dynamic heliosphere • Measuring the rotation speed of asteroids • Observing ambipolar diffusion and thermal jet motions in young stellar

objects • Measuring three-dimensional motions of ionized gas and stars in the center

of the Galaxy • Mapping the magnetic fields in individual galaxy clusters • Conducting unbiased searches for redshifted atomic and molecular

absorption • Looking through the enshrouding dust to image the formation of high-

redshift galaxies • Disentangling starburst from black hole activity in the early universe • Providing direct size and expansion estimates for up to 100 gamma-ray

bursts every year


EVLAcontinuum


Mileura Wide Field Array --- Low Frequency Demonstrator


Dipole Antennas




The Square Kilometer Array


LNSD Optimization

Weinreb 2007


Science Goals

• The Cradle of Life

• Strong field tests of gravity using pulsars and black holes

• Origin and evolution of magnetism

• Galaxy evolution and cosmoly

• Dark energy


“What are the basic properties of the fundamental particles and forces?”

Neutrinos, Magnetic Fields, Gravity, Gravitational Waves, Dark Energy

“What constitutes the missing mass of the Universe?”Cold Dark Matter (e.g. via lensing), Dark Energy, Hot Dark Matter (neutrinos)

“What is the origin of the Universe and the observed structure and how did it evolve?”

Atomic hydrogen, epoch of reionization, magnetic fields, star-formation history……

“How do planetary systems form and evolve?”

Movies of Planet Formation, Astrobiology, Radio flares from exo-planets……

“Has life existed elsewhere in the Universe, and does it exist elsewhere now?”

SETI

fundamental questions in physics

and astronomy


Technical Specs

• 1 km^2 collecting area– D_eff ~ 1000 m

• Frequency coverage from 0.1 to 25 GHz

• Baselines of 20 m to 3000 km

• FOV >~ 1 sq deg– Goal of 200 sq deg at 0.7 GHz



Inner core

Station

Reference Design

Wide-angle radio camera +

radio “fish-eye lens”

Reference Design


1% SKA Pathfinders - proving SKA technology

• Radio camera: small dishes+smart feeds-SKA Design Study (Europe)-Karoo Array Telescope (South Africa)-Extended New Technology Demonstrator (Australia)-Allen Telescope Array (USA)

• Radio fish-eye lens: aperture array tiles-SKA Design Study (Europe)-LOFAR (Netherlands)

• SKADS – study of end-to-end designEC-FP6, European countries, Australia, South Africa, Canada


EVLAcontinuum

SKA

10^6


2000

Site ranking

‘1% SKA’Science

ISSCMoAs

SiteSelection

ScienceCase

published

Inter-governmental discussions

First SKA WorkingGroup

Initial concept

2000

‘10% SKA’Science

92 96 04 05 06 07 08 09 10 14 18 22

Feasibility study

Full arrayBuild

100% SKA

SKAComplete

Phase 1Build

10% SKA

Conceptexposition

Define SKA

System

SKA timeline

Optimise Reference

Design

Construct 1% SKA “pathfinders”

Documents

The Transient Universe: AY 250 Spring 2007 New Radio Telescopes Geoff Bower