Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/people/Ray.Norris/papers/iau_atlas_poster.pdf Дата изменения: Thu Aug 3 03:42:35 2006 Дата индексирования: Sun Dec 23 09:00:10 2007 Кодировка: Поисковые слова: annular solar eclipse

ATLAS: Australia Telescope Large Area Survey:
Deep Radio Observations of the CDFS-SWIRE and ELAIS-S1 fields
Ray Norris1, Enno Middelberg1, JosИ Afonso5, Phil Appleton2, Brian Boyle1, Paolo Ciliegi6, Tim Cornwell1,Scott Croom4, Minh Huynh2, Carole Jackson1, Anton Koekemoer7, Carol Lonsdale3, Bahram Mobasher7, Seb Oliver8, Mari Polletta3, Brian Siana2, Ian Smail9, Maxim Voronkov1
1: CSIRO Australia Telescope, Sydney, Australia 2: Spitzer Science Center, California Institute of Technology, USA 3: University of California at San Diego, USA. 4: Anglo-Australian Observatory, Sydney, Australia. 5: Observatorio Astronomico de Lisboa, Portugal. 6, Bologna Astronomical Observatory, Italy. 7: Space Telescope Science Institute, Baltimore, USA. 8: University of Sussex, UK. 9: University of Durham, UK.

1. Overview
· We are imaging the CDFS and ELAIS-S1 SWIRE fields at 20 cm. Combining radio data with other wavelengths will help us understand the formation and evolution of early galaxies. · Radio observations give information which is not available at any other wavelength. For example, we have found galaxies with a starburst SED but with a vigorous buried AGN, invisible at any other wavelength. · When finished, this will be the widest (6o2) deep (10-15 µJy) radio survey ever. It will: · not be affected by dust obscuration, · uncover rare classes of object, · show obscured large-scale structure. The Australia Telescope Compact Array used to make the radio images in this paper. · This is an interim report ­ we are about half-way through the observations and have not yet reached our final sensitivity. · Stacking gives an rms20cm ~ 1.5 µJy and shows the radio-FIR correlation extends down to S20cm~10 µJy. · We identify a class of radio sources (IFRS=Infrared-faint radio sources) with no visible infra-red emission. These may be very obscured or very high-z galaxies. A typical part of the ELAIS-S1 field, showing examples of classical radio doubles and triples, isolated starburst galaxies, and a disturbed head-tail galaxy.

2. Observations & Data
GOODS CDFS

3. Results
Vital statistics · 6 square degrees observed so far to ~ 40µJy rms · Hope eventually to get to ~15 µJy rms · Spatial resolution ~ 6 arcsec · 1790 radio components detected so far · These correspond to 1642 sources (some have multiple components) · Nearly all are also detected by Spitzer

4. Science
Radio-FIR correlation at µJy levels
150 < F(24µm) < 238µJy 20cm rms = 1.5µJy

Exc. F(20cm) < 100µJy Nobj=1805

Stacking the radio data at the positions of known 24 µm sources enables us to probe very weak radio fluxes, and shows the radioFIR correlation holds down to 10 µJy.

ELAIS-S1

Infrared-faint Radio Sources

Some sources follow the radio-24µm correlation, indicating they are driven by star formation, while others have a strong radio excess, indicating AGN. These mJy radio source (contours) are undetected at 3.6µm (grayscale), or any other Spitzer band. About 3% of our radio sources with good Spitzer data have no IR counterparts, implying an unusually high radio-IR ratio. We call this new class of sources "Infrared-faint radio sources", or IFRS.

A typical part of the CDFS field with 20 cm radio contours overlaid on the 3.6 µm SWIRE image.

References: Norris et al., 2006, AJ, in press. Boyle et al., 2006, to be submitted to MNRAS. Middelberg et al., 2006, to be submitted to AJ.

Stacking 3.6µm Spitzer data (above) still shows no counterparts, implying they are well below the detection threshold. These IFRS may be very heavily obscured, or high-z, AGN.