e-MERLIN : a pathfinder for the SKAe-MERLIN : a pathfinder for the SKA(a summary of the e-MERLIN talk given at the Berkeley SKA meeting)(a summary of the e-MERLIN talk given at the Berkeley SKA meeting)

e-MERLIN : a pathfinder for the SKAe-MERLIN : a pathfinder for the SKA(a summary of the e-MERLIN talk given at the Berkeley SKA meeting)(a summary of the e-MERLIN talk given at the Berkeley SKA meeting)

P.J.DiamondP.J.DiamondP.J.DiamondP.J.Diamond

MERLIN/VLBI National FacilityMERLIN/VLBI National Facility

Jodrell Bank ObservatoryJodrell Bank Observatory

University of ManchesterUniversity of Manchester

MERLIN/VLBI National FacilityMERLIN/VLBI National Facility

Jodrell Bank ObservatoryJodrell Bank Observatory

University of ManchesterUniversity of Manchester

11/7/01 11/7/01

e-MERLIN www.merlin.ac.uk/e-merlin

• Fibre connection to telescopes; new correlator

• 2 GHz/pol instantaneous bandwidth

• Data rate increases from 128Mb/s/tel to 40Gb/s/tel

• Sensitivity ~ 1 Jy/b in 12hr (> 30 over current system)

• Correlator operates in permanent wide-field mode– e-MERLIN will provide FOV ~ 0.5 degree at 1.4 GHz,

~10 arcmin at 5 GHz. Images will have as many pixels as VISTA – 400,000,000 per channel

– Output data rate 0.5 TB/day

– Hundreds of sources in each observation – superb high-res archive for data mining (AstroGrid, e-science)

• Complete aperture coverage via MFS

e-MERLIN capabilities

Band Frequency

(GHz)

Current Sensitivity

(Jy)

e-MERLIN sensitivity

(Jy)

Brightness

(K)

Resolution

(arcsec)

UHF 0.327/0.408 700 200 7020 0.5

L 1.0 – 2.0 35 4 140 0.14

C 4.0 – 8.0 50 1.4 47 0.04

X 8.0 – 12.0 N/a 1.4 47 0.02

U 12.0 – 18.0 N/a 3.0 104 0.013

K 18.0 – 26.0 400 11.3 390 0.008

Key programme sensitivity: 200 hours at 5 GHz 350 nJy rms

e-MERLIN Science

• Cosmology – gravitational lenses, JVAS/CLASS,

constraints on cosmological parameters, e.g m and

Gravitational Lenses from JVAS/CLASSCurrent constraints: Red from supernovae e-MERLIN constraints

Green from Boomerang, JVAS/CLASS as contours

• Galaxy Formation & Evolution: nature of submm galaxies, starbursts, X-ray background.• 100’s of sources in primary beam.

e-MERLIN Science

HDF: contours are MERLIN+VLA 1.4 GHz emission, rms = 3.5Jy/beam

Statistical detection of < 10Jysources in HDF. Excess radio emission clearly seen for I <26,implying majority of galaxies at this level detectable by e-MERLIN

• Star-formation:– Imaging thermal jets and outflows in YSOs– Maser emission in star-formation regions

Studies of magnetic fields:masers, circular polzn fromplasmas, linear polzn of synchrotronsources

MERLIN 6cmMeaburn et al

Ori A

Non-thermal radio source

Trapezium Cluster

e-MERLIN Science

1400 AU

Subaru

HST300 AU

MERLIN

Seeing through the dust: 150 magnitudes

of optical extinction

Gemini

BD +30o 3639

Planetary Nebulae

MERLIN Chandra

• Main sequence and evolved stars – novae, stellar coronae,

planetary nebula, surfaces of supergiants/giants

e-MERLIN Science

Nova V723 Cas

MERLIN 6cmVLA 7mm

Imaging stellar surfaces

• Extreme environment astrophysics – micro-quasars, relativistic jets in AGN, pulsar proper motions, GRBs ……

e-MERLIN will provide detailed images

of Cygnus A-like objects at 10 times the

distance currently possible.

e-MERLIN Science

e-MERLIN: straw-man timetable (now out of date)

Fibres Installed

LT upgraded

5 year timeline

Cost of leasing dark fibre

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

1996 1997 1998.5 1999.5 2000.5 2001.5

Euro/Mbps/yr

0

1

2

3

4

5

6

1996 1997 1998.5 1999.5 2000.5 2001.5

Euro/Mbps/yr

e-MERLIN status

• Re-scoped project: – deferred 12-18 GHz system

– adopted ALMA data transmission system => 1.5 GHz bandwidth (i.e. 12.5% hit in sensitivity)

– Cost now £7.0M

• March, 2001 --- highly rated by Astronomy Committee

But no capital cost available from PPARC.

• May 2001, final resolution of capital cost:– NWDA: £2.5M

– SRIF: UMan £2.0M, UMIST £0.25M, UCam £0.25M

– Savings on MERLIN Ops: £1.3M

– U Manchester willing to underwrite remainder: £0.7M

£7.0M

e-MERLIN status• Current status:

– Negotiations underway with PPARC on future operating costs

– September, cost and risk assessment

– Early 2002 start project build phase.

From e-MERLIN to SKA• Develop digital, fibre etc technologies essential for SKA

• Learn how to operate fibre-based system with SKA-like baselines

and in hostile RFI environment

• Maintain British astronomical expertise in cm-wave interferometry

• e-MERLIN will have Jy sensitivity at < 0.1 arcsec resolution

demonstration of range of science possible with SKA