Browse
this table...

VLAECDFSOI - VLA Extended-Chandra Deep Field-South 1.4-GHz Sources Opt/IR Counterparts

HEASARC
Archive

Overview

This table contains a sample of 883 sources detected in a deep Very Large Array (VLA) survey at 1.4 GHz in the Extended-Chandra Deep Field South (E-CDFS). The reference paper focuses on the identification of their optical and infrared (IR) counterparts. The authors use a likelihood-ratio technique that is particularly useful when dealing with deep optical images to minimize the number of spurious associations. They find a reliable counterpart for 95% of their radio sources. Most of the counterparts (74%) are detected at optical wavelengths, but there is a significant fraction (21%) that are only detectable in the IR. Combining newly acquired optical spectra with data from the literature, the authors are able to assign a redshift to 81% of the identified radio sources (37% spectroscopic). They also investigate the X-ray properties of the radio sources using the Chandra 4 Ms and 250 ks observations. In particular, the authors use a stacking technique to derive the average properties of radio objects undetected in the Chandra images. The results of their analysis are collected in this new catalog containing the position of the optical/IR counterpart, the redshift information, and the X-ray fluxes. It is the deepest multi-wavelength catalog of radio sources, which will be used for future study of this galaxy population.

The E-CDFS was observed at 1.4 GHz with the VLA between 2007 June and September (Miller et al. 2008, ApJS, 179, 114). The mosaic image covered an area of about 34 by 34 arcminutes with near-uniform sensitivity. The typical rms is 7.4 microJy for a 2.8 by 1.6 arcseconds beam. The second data release (N. Miller et al. 2012, in preparation) provides a new source catalog with a 5-sigma point-source detection limit, for a total of 883 sources. The median value of the distribution is 58.5 microJy and the median signal-to-noise ratio (S/N) is 7.6. The authors note that ~ 90% of the sample has a flux density below 1 mJy, a regime where radio-quiet AGNs and star-forming galaxies (SFGs) become the dominant populations


Catalog Bibcode

2012ApJS..203...15B

References

The Sub-mJy Radio Population of the E-CDFS: Optical and Infrared Counterpart
Identification
     Bonzini M.; Mainier V.; Padovani P.; Kellermann K. I.; Miller N.;
     Rosati P.; Tozzi P.; Vattakunnel S.; Balestra I.; Brandt W. N.; Luo B.;
     Xue Y.Q.
    <Astrophys. J. Suppl., 203, 15 (2012)>
    =2012ApJS..203...15B

Provenance

This table was created by the HEASARC in November 2012 based on the files table3.dat and table5.dat which were obtained from the ApJS web site.

Parameters

Source_Number
The uniquely identifying radio source sequence number (RID) in order of increasing J2000.0 Right Ascension.

Name
The radio source designation using the prefix '[BMP2012] RID' for Bonzini, Mainieri, Padovani 2012 radio identification and the source number, in a style based on that recommended by the Dictionary of Nomenclature of Celestial Objects. In the reference paper itself, these sources are referred to without the first part of the prefix, e.g., as 'RID 360'.

RA
The Right Ascension of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Flux_1p4_GHz
The flux density of the radio source, in milliJansky (mJy). This was converted by the HEASARC from the microJansky (uJy) units used in the original table in the reference paper. The authors use the peak flux density or the integrated flux density according to the specifications of N. Miller et al. (2012, in preparation).

Flux_1p4_GHz_Error
The 1-sigma error in the flux density of the radio source, in milliJansky (mJy). This was converted by the HEASARC from the microJansky (uJy) units used in the original table in the reference paper.

SNR_1p4_GHz
The signal-to-noise ratio of the radio source detection.

Ctrpart_RA
The Right Ascension of the counterpart to the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table. The counterpart position was taken from an optical catalog, when available, since these observations have the highest spatial resolution. In particular, the authors chose the catalog in which the counterpart had the highest reliability. If there was no optical counterpart above the reliability threshold, they used the coordinates of the most reliable counterpart found in the NIR catalogs. More details of the counterpart identification procedure are given in Section 3 of the reference paper. This field is left blank if no counterpart was identified.

Ctrpart_Dec
The Declination of the counterpart to the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds in the original table. The counterpart position was taken from an optical catalog, when available, since these observations have the highest spatial resolution. In particular, the authors chose the catalog in which the counterpart had the highest reliability. If there was no optical counterpart above the reliability threshold, they used the coordinates of the most reliable counterpart found in the NIR catalogs. More details of the counterpart identification procedure are given in Section 3 of the reference paper. This field is left blank if no counterpart was identified.

Assoc_Reliability
The reliability Rel of the association of the optical and/or infrared counterpart with the radio source, as defined in Section 3 of the reference paper. Sources whose identifications have been revisited (see Section 3.4 of the reference paper) or for which the counterpart position has been extracted from the IRAC image (see Section 3.2) have Rel = 9.0. The HEASARC notes that, in addition to 19 such entries having Rel = 9.0 in this table, there are an additional 4 cases with Rel > 9.0 (9.01,9.44, 9.99 and 10.00) the significance of whose values is unclear.

Offset
The angular distance between the radio source and the counterpart, in arcseconds.

Ctrpart_Catalog
The catalog from which the counterpart was selected, as detailed in Table 1 of the reference paper.

Rmag
The R-band AB magnitude of the counterpart from the WFI Catalog.

Rmag_Error
The error in the R-band AB magnitude of the counterpart from the WFI Catalog.

Ks_Mag
The KS-band AB magnitude of the counterpart from the MUSYC Catalog.

Ks_Mag_Error
The error in the KS-band AB magnitude of the counterpart from the MUSYC Catalog.

IRAC_3p6_um_Mag
The 3.6-micron-band AB magnitude of the counterpart from the IRAC SIMPLE Catalog.

IRAC_3p6_um_Mag_Error
The error in the 3.6-micron-band AB magnitude of the counterpart from the IRAC SIMPLE Catalog

Redshift
The 'best' redshift of the counterpart: this is derived spectroscopically if the value of the redshift_flag parameter is >= 2, else it is derived photometrically. The measurement of redshifts is discussed in Section 4 of the reference paper.

Phot_Redshift
The photometric redshift of the counterpart. The derivation and source of the photometric redshifts is discussed in Section 4.3 of the reference paper.

Phot_Redshift_Neg_Err
The lower 68% uncertainty in the value of the photometric redshift.

Phot_Redshift_Pos_Err
The upper 68% uncertainty in the value of the photometric redshift.

Ref_Phot_Redshift
The reference for the photometric redshift using the following codes (see Section 4.3 of the reference paper for further details):

  Code     Meaning

  ZEB-pz   derived using the Zurich Extragalactic Bayesian Redshift Analyzer
           (ZEBRA) code (Feldmann et al. 2006, MNRAS, 372, 565)
  C10_pz   MUSYC-E-CDFS  (Cardamone et al. 2010, ApJS, 189, 270)
  KM_pz    K-selected MUSYC Catalog (Taylor et al. 2009, ApJS, 183, 295)
  S09_pz   GOODS-MUSYC Catalog (Santini et a. 2009, A&A, 504, 751)
  

Spect_Redshift
The spectroscopic redshift of the counterpart. The derivation and other sources for the spectroscopic redshifts is discussed in Sections 4.1 and 4.2 of the reference paper.

Redshift_Flag
This flag parameter indicates the quality of the redshift as follows:

  3 = secure redshift,
  2 = reasonable redshift,
  1 = one-line detection or tentative redshift.
  

Ref_Spect_Redshift
The reference for the source of the spectroscopic redshift using the labels given in Table 4 of the reference paper.

SB_Xray_Flux
The soft-band X-ray flux (0.5-2 keV) of the X-ray counterpart, in erg s-1 cm-2. The HEASARC notes that there are 18 entries with soft-band fluxes less than the 9.1 x 10-18 erg s-1 cm-2 on-axis flux limit for the Chandra 4-Ms exposure which may be considered suspect

SB_Xray_Flux_Error
The error in the soft-band X-ray flux (0.5-2 keV) of the X-ray counterpart, in erg s-1 cm-2.

HB_Xray_Flux
The hard-band X-ray flux (2-10 keV) of the X-ray counterpart, in erg s-1 cm-2.

HB_Xray_Flux_Error
The error in the hard-band X-ray flux (2-10 keV) of the X-ray counterpart, in erg s-1 cm-2.

Xray_Source_Number
The X-ray source identifier, taken from Xue et al. (2011, ApJS, 195, 10) if < 1000, or from Lehmer et al. (2005, ApJS, 161, 21) if > 1000, where the quoted number is Lehmer's ID + 1000. The HEASARC notes that there are 4 entries with values of -99 the significance of which is not specified.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 17-Dec-2012