VLAECDFSCLS - VLA Extended-Chandra Deep Field-South Classification Catalog

Overview

The sub-mJy radio population is a mixture of active systems, that is star-forming galaxies (SFGs) and active galactic nuclei (AGNs). In their paper, the authors study a sample of 883 radio sources detected at 1.4 GHz in a deep Very Large Array (VLA) survey of the Extended Chandra Deep Field-South (E-CDF-S) that reaches a best rms sensitivity of 6 microJansky (uJy). The authors have used a simple scheme to disentangle SFGs, radio-quiet (RQ), and radio-loud (RL) AGNs based on the combination of radio data with Chandra X-ray data and mid-infrared observations from Spitzer. They find that at flux densities between about 30 and 100 uJy, the radio population is dominated by SFGs (~60%) and that RQ AGNs become increasingly important over RL ones below 100 uJy. In the paper, the authors also compare the host galaxy properties of the three classes in terms of morphology, optical colors and stellar masses. Their results show that both SFG and RQ AGN host galaxies have blue colors and late-type morphology while RL AGNs tend to be hosted by massive red galaxies with early-type morphology. This supports the hypothesis that radio emission in SFGs and RQ AGNs mainly comes from the same physical process: star formation in the host galaxy.

Catalog Bibcode

2013MNRAS.436.3759B

References

The sub-mJy radio sky in the Extended Chandra Deep Field-South: source
population.

    Bonzini M., Padovani P., Mainieri V., Kellermann K.I., Miller N.,
    Rosati P., Tozzi P., Vattakunnel S.
   <Monthly Notices of the Royal Astronomical Society, Volume 436, p.3759-3771>
   =2013MNRAS.436.3759B

Provenance

This table was created by the HEASARC in January 2014 based on the machine-readable version of Table 1 from the reference paper which was obtained from the MNRAS web site.

Parameters

Source_Number
The uniquely identifying radio source sequence number (RID) in order of increasing J2000.0 Right Ascension. This corresponds to that given in Miller et al. (2013, ApJS, 205, 13: the HEASARC table VLAECDFS1P4) and Bonzini et al. (2012, ApJS, 203, 15; the HEASARC table VLAECDFSOI).

Name
The radio source designation using the prefix '[BMP2012] RID' for the original Bonzini, Mainieri, Padovani 2012 paper which listed the radio identification and the radio source number (RID), and the radio source number (RID number), in a style based on that recommended by the Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the optical/IR 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. For the 44 sources without any optical, IR or X-ray counterpart no positions were given in the original table. For all such sources (indicated by having a position_flag value of 'R'), the HEASARC has substituted the position of the radio source itself, as given in Bonzini et al. (2012, ApJS, 203, 15; the HEASARC table VLAECDFSOI).

Dec
The Declination of the optical/IR 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. For the 44 sources without any optical, IR or X-ray counterpart no positions were given in the original table. For all such sources (indicated by having a position_flag value of 'R'), the HEASARC has substituted thye position of the radio source itself, as given in Bonzini et al. (2012, ApJS, 203, 15; the HEASARC table VLAECDFSOI).

LII
The Galactic Longitude of the optical/IR counterpart to the radio source, or, if position_flag = 'R', of the radio source itself.

BII
The Galactic Latitude of the optical/IR counterpart to the radio source, or, if position_flag = 'R', of the radio source itself.

Position_Flag
This HEASARC-created flag parameter is set to 'R' to indicate that the quoted position is that of the radio source since no counterpart has been identified.

Broad_Type
The classification of the radio source using the criteria discussed in the reference paper, where 'SFG' means Star-Forming Galaxy, 'RQ AGN', Radio-Quiet AGN, and 'RL AGN=', Radio-Loud AGN.

Redshift
The redshift of the source.

Log_L_Rad
The logarithm of the radio power of the source, in W Hz^-1.

Log_Lx_Limit
This limit flag parameter is set to '<' if the quoted value of the logarithm of the unabsorbed X-ray luminosity is a 3-sigma upper limit rather than a detection.

Log_Lx
The logarithm of the unabsorbed X-ray luminosity in the hard band (2-10 keV), in erg s^-1 (or of the 3-sigma upper limit if not detected in X-rays).

Q24_Obs_Limit
This limit flag parameter is set to '<' if the quoted value of the logarithm of the ratio of the observed 24-micron and 1.4-GHz luminosities q24_obs is an upper limit rather than an actual value.

Q24_Obs
The logarithm of the ratio of the observed 24-micron and 1.4-GHz luminosities, q24_obs, of the source (or upper limit thereof if the corresponding limit flag = '<'). The use of the observed flux densities rather than the rest-frame ones minimizes the uncertainties due to modeling according to the authors. In the case of resolved radio sources, the authors used the integrated radio flux densities.

Log_Ratio_5p8_3p6_um
The first IRAC color of the infrared counterpart to the radio source, defined as the logarithm of the ratio of the 5.8-um flux density to the 3.6-um flux density.

Log_Ratio_8p0_4p5_um
The second IRAC color of the infrared counterpart to the radio source, defined as the logarithm of the ratio of the 8.0-um flux density to the 4.5-um flux density.

Radio_Spectral_Index
The radio spectral index of the source, alpha_r. This has been set to 0.7 if no 6-cm observations were available. The data sets used to calculate alpha_r are discussed in Section 3.5.1 of the reference paper.

Abs_Bmag
The rest-frame absolute B-magnitude of the radio source counterpart.

Class_Quality_Flag
The quality flag QF of the source classification, ranging from 3 for a secure classification, i.e., one for which all of the various classification criteria agree or are at least not in contradiction, to 1 for a tentative classification. Sources with classifications flagged as 3 comprise 45% of the total sources. The authors set QF to 2 to sources with q24_obs values just above the RL AGN threshold (q24_obs,M82 - 2 sigma < q24_obs < q24obs_,M82 - 1 sigma). Sources without redshift but with a clear signature of AGN activity also have QF = 2. A total of 18% of the sources have QF = 2. The remaining sources have classification flag values QF = 1. Examples of this last category are sources without redshifts and without clear signature of AGN activity or without an optical/IR counterpart. Also sources with upper limits to the X-ray luminosity > 10⁴² erg s^-1, not in the Donley wedge, and above the RL AGN threshold have QF = 1. These sources are classified as SFGs but, even if the authors can exclude that they are RL AGNs, there might be a contamination from RQ AGNs.

Class
The HEASARC Browse object classification based on the value of the broad_type parameter.

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: Wednesday, 15-Jan-2014 15:27:54 EST