From Jodrell Bank: “e-MERLIN’s deep radio survey of the Hubble Deep Field: first results”

Jodrell Bank Lovell Telescope
Lovell

Jodrell Bank Centre for Astrophysics

27 March 2012 [in RSS Jan 25, 2013]

“A team of astronomers at Jodrell Bank Observatory have begun the deepest ever high-resolution radio imaging of the region around the Hubble Deep Field (HDF), the images originally captured by the Hubble Space Telescope (HST) in the mid 1990s. The HDF led to the discovery of numerous galaxies billions of light years distant and provided direct visual evidence of the evolution of the Universe. First results from the new imaging, which uses observations from the UK’s newly upgraded e-MERLIN radio telescope array together with the EVLA radio array based in New Mexico, show galaxies some 7 billion light years away in unprecedented detail.

hdf
About 1,500 galaxies are visible in this deep view of the universe, taken by allowing the Hubble Space Telescope to stare at the same tiny patch of sky for 10 consecutive days in 1995. The image covers an area of sky only about width of a dime viewed from 75 feet away. Credit: Robert Williams and the Hubble Deep Field Team (STScI) and NASA

e-MERLIN is an array of radio telescopes distributed across the United Kingdom connected together by optical fibres. Data from each telescope is sent across this network to Jodrell Bank where a device known as a ‘correlator’ processes them into a single image. This technique, known as interferometry, simulates a single radio telescope hundreds of kilometres across and produces exceptionally sharp images of astronomical objects.

EVLA is a similar more compact array in New Mexico in the United States that shows the coarser structure of objects and complements the e-MERLIN observations. The two arrays started to survey the HDF region in 2011 and the team expect the project to be completed in the next few years.

hdf2
Image composed from e-MERLIN and EVLA observations in C-band. The width of the whole field is approximately 1/4 of a degree (the same diameter as half a full moon). The inset images illustrate the effectiveness of e-MERLIN’s capabilities in revealing the structure of galaxies even at distances of billions of the light years. Bottom left: An interesting example of an AGN galaxy with large lobes thought to be caused by jets, emanating from a central black hole, interacting with interstellar material. Bottom right: An FR1 type AGN galaxy. Top left: A more typical AGN type galaxy. Top right: An AGN with star formation characteristic emission detected at an estimated distance of 7.5 billion light-years. Credit: N. Wrigley / Jodrell Bank Centre for Astrophysics

The first wide-band images of the whole HDF region capture the brightest objects in the field at sub-arcsecond resolution, equivalent to being able to distinguish a ten pence piece at a distance of over 5 kilometres. The pictures were assembled by Mr [Nick] Wrigley under the supervision of Dr Rob Beswick and Dr Tom Muxlow at the Jodrell bank Centre for Astrophysics in Manchester. The image in the background, observed using the EVLA, shows the unresolved emission from whole galaxies, whereas the inset images produced using mapping in combination with e-MERLIN show the fine detail.

This new work is just the start of a multi-year survey of the HDF and provides a glimpse of the capabilities of wide-band (broadband data transmission) synthesis imaging now possible with simultaneous use of the e-MERLIN and EVLA arrays. Crucially, the e-MERLIN and EVLA correlators now generate compatible data allowing future observations to be combined like never before.”

See the full article here.

Jodrell Bank Centre for Astrophysics comprises research activities in astronomy and astrophysics at The University of Manchester, the world leading facilities of the Jodrell Bank Observatory, the e-MERLIN/VLBI National Facility and the Project Development Office of the Square Kilometre Array.

Jodrell Bank e-Merlin

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