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AEGIS20 - All-Wavelength Extended Groth Strip Int. Survey (AEGIS) VLA 20-cm Source Catalog

HEASARC
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Overview

This table contains results from AEGIS20, a radio survey of the Extended Groth Strip (EGS) conducted with the Very Large Array (VLA) at a frequency of 1.4 GHz. The resulting catalog contains 1122 emitters (HEASARC Note: The abstract of the original reference paper said 1123, but as noted by Willner et al. (2012, ApJ, 756, 72: footnote 10, one entry ('EGS20 J142303.7+532224.5') was listed twice in the original catalog), and it is sensitive to ultraluminous (1012 solar luminosities) starbursts to z <= 1.3, well matched to the redshift range of the DEEP2 spectroscopic survey in this region. The authors use stacking techniques to explore the microJansky-level emission from a variety of galaxy populations selected via conventional criteria - Lyman break galaxies (LBGs), distant red galaxies (DRGs), UV-selected galaxies, and extremely red objects (EROs) - determining their properties as a function of color, magnitude, and redshift and their extinction-free contributions to the history of star formation. This study confirms the familiar pattern that the star formation rate (SFR) density, increases by at least a factor of ~ 5 from z = 0 to 1, although the authors note highly discrepant UV- and radio-based SFR estimates. Their radio-based SFRs become more difficult to interpret at z > 1 where correcting for contamination by radio-loud active galactic nuclei (AGNs) comes at the price of rejecting luminous starbursts. While stacking radio images is a useful technique, accurate radio-based SFRs for z >> 1 galaxies require precise redshifts and extraordinarily high fidelity radio data to identify and remove accretion-related emission.

Data were obtained at 1.4 GHz during 2003 to 2005 with the VLA in its B configuration, acquiring seven 3.125 MHz channels every 5 s at each of four intermediate frequencies. Data were obtained at six positions, spaced by 15 arcminutes, concentrating in the northern half of the EGS because of the proximity of 3C 295 (a 23 Jy source at 1.4 GHz). Around 18 hours of data were acquired for each of the field positions. Calibrated visibilities and associated weights were used to generate mosaics of 37 x 5122 x 0.8 arcsec2 pixel images to quilt the VLA's primary beam in each EGS field position. CLEAN boxes were placed tightly around all sources, and a series of IMAGR and CALIB tasks were run, clipping the UV data after subtracting CLEAN components generated by the third iteration of IMAGR. The central images from each of the pointings were then knitted together using FLATN, ignoring data beyond the primary beam's half-power point, to produce a large mosaic. The synthesized beam is circular, with a FWHM of ~ 3.8 arcseconds. To define a sample of radio sources, the authors searched signal-to-noise ratio (S/N) images using the SAD detection algorithm, emulating the technique described by Biggs & Ivison (2006, MNRAS, 371, 963). Sources with >= 4-sigma peaks were fitted with two-dimensional Gaussians using JMFIT, and those with >- 5-sigma peaks that survived were fitted in total intensity. Sources with sizes equal to or smaller than the restoring beam were considered unresolved. No correction is made for bandwidth smearing in the catalog; this is a small effect (~ 5%) given the mosaicking strategy and the use of the B configuration. 38, 79, 171, 496, and 1123 sources are detected with 1.4 GHz flux densities >= 2000, >= 800, >= 320, >= 130 and >= 50 microJansky (uJy) [including the duplicate source mentioned above], where the 5-sigma detection limits at 130 and 50 uJy cover 0.73 and 0.04 deg2, respectively. Confusion is not an issue; the source density on an arcmin2 scale is < 0.01 beam-1.


Catalog Bibcode

2007ApJ...660L..77I

References

AEGIS20: A Radio Survey of the Extended Groth Strip
       Ivison R.J., Chapman S.C., Faber S.M., Smail I., Biggs A.D.,
       Conselice C.J., Wilson G., Salim S., Huang J.-S., Willner S.P.
       <Astrophysical Journal, Volume 660, Issue 1, pp. L77-L80>
       =2007ApJ...660L..77I

Provenance

This table was created by the HEASARC in July 2013 based on an electronic versions of the catalog described in the reference paper which was obtained as a FITS file from the first author's web site at http://www.roe.ac.uk/~rji/aegis20/.

Parameters

Name
The IAU-style J2000.0 position-based designation of the radio source, using the prefix 'EGS20' (for Extended Groth Strip, 20 cm) for these names in accordance with the naming convention registered with the Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates decimal degrees in the original tables.

Dec
The Declination of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates decimal degrees in the original tables.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

RA_Error
The uncertainty in the Right Ascension of the radio source, in seconds of time. Values of -1.0 for this parameter in the original version of this catalog have been converted to nulls in this HEASARC table.

Dec_Error
The uncertainty in the Declination of the radio source, in arcseconds. Values of -1.0 for this parameter in the original version of this catalog have been converted to nulls in this HEASARC table.

Flux_20_cm
The peak flux density of the radio source at 1.4 GHz (20 cm), in mJy/beam (converted by the HEASARC from the uJy/beam units used in the original version of this catalog).

Flux_20_cm_Error
The uncertainty in the peak flux density of the radio source at 1.4 GHz (20 cm), in mJy/beam (converted by the HEASARC from the uJy/beam units used in the original version of this catalog). Values of -1.0 for this parameter in the original version of this catalog have been converted to nulls in this HEASARC table.

Int_Flux_20_cm
The integrated flux density of the radio source at 1.4 GHz (20 cm), in mJy (converted by the HEASARC from the uJy units used in the original version of this catalog).

Int_Flux_20_cm_Error
The uncertainty in the integrated flux density of the radio source at 1.4 GHz (20 cm), in mJy (converted by the HEASARC from the uJy units used in the original version of this catalog). Values of -1.0 for this parameter in the original version of this catalog have been converted to nulls in this HEASARC table.

Major_Axis
The major axis of the radio source, in arcseconds, after deconvolution with the synthesized circular beam of ~ 3.8" FWHM.

Minor_Axis
The minor axis of the radio source, in arcseconds, after deconvolution with the synthesized circular beam of ~ 3.8" FWHM. Values of -1.0 for this parameter in the original version of this catalog have been converted to nulls in this HEASARC table.

Position_Angle
The position angle of the deconvolved major axis of the radio source, in degrees, measured eastwards from north.


Contact Person

Questions regarding the AEGIS20 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 23-Jul-2013