University of Sydney Facilities

17 Dec 2004 E.M. Sadler 1

University of Sydney Facilities

Sydney University Stellar Interferometer (SUSI)

Molonglo Radio Telescope (MOST/SKAMP)

Used for research in both astronomy/astrophysics and instrumentation. Funded by external competitive grants. Important role in student training.

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Who’s involved?

SUSI: Peter Tuthill, John Davis, Mike Ireland, Andrew Jacob, Julian North, John O’Byrne, Steve Owens, Gordon Robertson, Bill Tango

MOST/SKAMP: Anne Green, Richard Hunstead, Elaine Sadler, Duncan Campbell-Wilson, Tim Adams, John Barry, Adrian Blake, John Bunton, Julia Bryant; David Crawford, Helen Johnston, Mike Kesteven, Greg Kingston, Martin Leung, Daniel Mitchell, Tom Mauch, Barbara Piestrzynska, Tony Turtle, Sergiy Vinogradov

Plus Australian and overseas collaborators

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SUSI: A pictorial introduction

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SUSI Science Programs

New red (500-900 nm) beam-combiner is now fully commissioned and science program underway

Single Stars• Diameters, Effective Temperature scale• Stellar atmosphere studies• Winds, shells, circumstellar matter• Rapid Rotators - Oblateness• Pulsating Stars, Cepheid distance scale

Binary Stars• Double-lined spectroscopic binaries give mass, distance• Ellipsoidal Variables – multiple distortions• Low Mass/Faint companions

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Delta Canis Majoris at 700 nm

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 5 10 15 20 25 30 35 40 45 50

Projected Baseline (m)

Correlation

(Preliminary data processing)

Angular Diameter: CMa (F8 Ia)

Angular diameter = 3.471 +/- 0.022 mas

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Angular Diameter of l Carinae against Phase

2.4

2.5

2.6

2.7

2.8

2.9

3.0

0.0 0.5 1.0 1.5Phase

Angular Diameter (mas)

SUSI 700nm UD Diameters (prelim)Repeated dataDay ticks

1 day intervals

Cepheid l Car: Diameter Variations

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Molonglo Observatory Synthesis Telescope

Array of 600 cylinders, each 111 x 15 m (area 1650 m2)

Prototype: SKAMP (10,000 m2) operating to 1 GHz by 2007

1.6km cylindrical reflector, currently operating at 843 MHz. Largest radio telescope in the southern hemisphere.

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Wide-field images of the radio sky

‘Radio Schmidt’ telescope: 2.7o field of view, excellent surface-brightness sensitivity

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Sydney University Molonglo Sky Survey (SUMSS)

www.astrop.physics.usyd.edu.au/SUMSS

SUMSS: Imaging survey of the entire southern sky, at similar sensitivity and resolution to the northern NVSS. Now 95% complete: FITS images and catalogue released on the web.Key science:• Local radio source populations to z~0.3• Angular clustering at z~1• Radio galaxies at z>3

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SUMSS and optical redshift surveys

Overlap with 2dF/6dF gives spectra of 10,000+ radio AGN and starburst galaxies.

Local radio luminosity functions and timescales; local benchmark for high-z studies.

6dFGS spectra

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Clustering studies with SUMSS

Angular (two-point) correlation function: w() = A

(Blake et al. 2004)

3-D clustering studies now in progress using SUMSS/NVSS/6dFGS (Mauch & Rawlings 2005 )

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SKA Molonglo Prototype (SKAMP)

Goal: To equip the Molonglo telescope with new feeds, low-noise amplifiers, digital filterbank and FX correlator with the joint aims of:

(i) developing and testing SKA-relevant technologies and

(ii) providing a powerful new facility for low-frequency radio astronomy in Australia

A$1.9 million funding from 2001 MNRF grant, ARC Linkage program and University of Sydney: timescale 2002-2007, PI Anne Green

International technology demonstrator for the cylindrical reflector SKA concept (one of six SKA designs currently being evaluated)

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From MOST to SKAMP:A three-stage approach

I. 2004-5: Narrowband continuum correlator (843 MHz, 4 MHz bandwidth, 88+2 stations = 4,000 baselines) [In parallel with SUMSS]

II. 2005-6: Increase bandwidth and add spectral capability (830-860 MHz, 4,000 baselines, 2,000 frequency channels) [Uses existing linefeed]

III. 2006-7: New linefeed + enhanced correlator (300-1420 MHz, >50 MHz bandwidth, 4,000 baselines, 2,000 frequency channels) [New wide-band linefeed for ~10% of collecting area is funded under MNRF; additional ~$1 million would equip full 18,000 m2 collecting area with new line feeds and new mesh]

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Stage I correlator: high-dynamic range continuum imaging

2004: Stage I correlator will allow use of self-calibration methods on MOST

Current MOST imaging dynamic range is 100-200:1 (similar to intrinsic dynamic range of VLA)

Use of self-calibration on VLA enabled imaging dynamic ranges of 105-106:1

Current imaging dynamic range of MOST limits imaging of faint sources (eg young supernova remnants) near

bright sources (eg Galactic Centre)

(MGPS Green et. al.)

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Stage II: FX correlator, spectral-line capability

2005-2006: 2,000 spectral channel FX correlator operating at 830-860 MHz enables, eg:• Measurements of HI absorption at z = 0.7 to 0.8 that capitalise on the large collecting area of MOST• OH megamaser emission surveys at z~1• Observing recombination lines of C and H, which set constraints on physical conditions in the ISM (Anantharamaiah & Kantharia 1999)

Stage II enables absorption-line measurements at z = 0.7 to 0.8, where

existing methods work poorly

(Lane 2000)

(Lane and Briggs 2001)

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Stage III Target Specifications

Parameter 1420 MHz 300 MHz

Frequency Coverage 300–1420 MHz

Instantaneous Bandwidth >50 MHz

Resolution ( < -30°) 26" x 26" csc|| 123" x 123" csc||

Imaging field of view 1.5° x 1.5° csc|| 7.7° x 7.7° csc||

uv coverage Fully sampled

Tsys < 50K < 150K

System noise (1) 12hr8 min

11 Jy/beam100 Jy/beam

33 Jy/beam 300 Jy/beam

Polarisation Dual Linear

Correlator Full Stokes

Frequency resolution 120–1 kHz (FXF mode down to 1 Hz)

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SKAMP III science example: HI emission from distant galaxies

8

9

10

11

0 0.05 0.1 0.15 0.2 0.25 0.3

Redshift z

HIPASS (500s)

SKAMP III (10x12 h)

(12 h)

log 10

Mli

m (

HI)

(M

sun)

Typical bright spiral

HI in the nearby Circinus galaxy (Jones et al. 1999)

SKAMP should reach HI mass limits typical of bright spiral galaxies at z=0.2 (lookback time ~3 Gyr), allowing a direct measurement of evolution in the HI mass function.

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Summary

SUSI: Now fully-operational. Unique capabilities as a visible-light interferometer, and science program likely to continue for at least five years. Could also be used as a technology testbed for Antarctic interferometers.

Molonglo: SUMSS survey 95% complete; new science program from 2006 using spectral-line capability.

SKAMP: Vital pathfinder to aspects of SKA technology [cylindrical antennas; software beam-forming; high dynamic-range imaging with fully-sampled uv plane], and hence an important partner to other efforts such as NTD. Modest additional funding (~$1 million) could provide a powerful science instrument with complementary strengths to xNTD.

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Binary star system: Cen

-30

-25

-20

-15

-10

-5

0

5

10

-15 -10 -5 0 5 10 15 20 25 30

y (mas)

x (mas)

1995 MAPPIT Observation

1997 SUSI Observations

1998 SUSI Observations

1999 SUSI Observations

2000 SUSI Observations

Fitted Orbit

E

N

Period: 357.0±0.3 daysInclination: 67.5±0.4 degSemi-major axis: 25.3±0.2 mas