SAXHELLASR - BeppoSAX High-Energy Large Area Survey (HELLAS) Radio Source Catalog

Overview

This table contains results of a complete radio follow-up obtained with the VLA and ATCA radio telescopes down to a 6-cm flux limit of about 0.3 mJy (3-sigma) of all the 147 X-ray sources detected in the BeppoSAX HELLAS survey (Fiore et al. 2001, MNRAS, 327, 771). The authors found 53 X-ray/radio likely associations, corresponding to about one-third of the X-ray sample. Using the two-point spectral index alpha_ro = 0.35 they divided all the HELLAS X-ray sources into radio-quiet and radio-loud. They have 26 sources classified as radio-loud objects, corresponding to 18 per cent of the HELLAS sample. In agreement with previous results, the identified radio-loud sources are associated mainly with Type 1 active galactic nuclei (AGNs) with L_5-10keV >~ 10⁴⁴ erg/s, while all the identified Type 2 AGNs and emission-line galaxies are radio-quiet objects with L_5-10keV <~ 10⁴⁴ erg/s.

The 20 HELLAS sources with Declinations south of -40^o were observed with the ATCA, while the 127 sources with more northerly Declinations were observed with the VLA. For these latter sources a complete covering at 20 cm down to the 5-sigma flux limit of 2.5 mJy is already available with the NRAO/VLA Sky Survey (NVSS) while the FIRST survey (Faint Images of the Radio Sky at Twenty centimeters) is available only for 27 HELLAS sources (5-sigma limit of ~ 1 mJy).In order to obtain information also on the radio spectral properties of the HELLAS sources the authors adopted the following strategy. All the 147 HELLAS sources were observed at 6 cm down to a 1 -sigma flux limit of ~ 0.10 - 0.25 mJy. For the 20 HELLAS sources observed with the ATCA, they took advantage of the fact that the 6 and 3 cm receivers of the ATCA share a common feed-horn and they observed simultaneously also at 3 cm, obtaining a 3-cm flux limit of ~ 0.22 mJy (1-sigma level).

Starting from the radio position of the 53 X-ray/radio associations, the authors searched for optical counterparts within 5 arcseconds from the radio position using the optical positions of the 61 HELLAS sources identified by La Franca et al. (2002, ApJ, 570, 100 = LF02), the USNO-A2.0 1 optical catalog, the APM 2 optical catalog and the NASA Extragalactic Database (NED). 24 X-ray/radio associations have been identified with sources in LF02 (10 Type 1 AGN, 4 Type 2 AGN, 2 BL Lacs, 3 Clusters, 4 ELGs and 1 Radio galaxy), 1 has been identified with a z = 0.708 Radio galaxy in the Lockman Hole using NED (see Table 2 source 116 in Lehmann et al. 2000, A&A, 354, 35 for a description of this source), 13 have an optical (R-band) identification in the USNO and/or APM catalogue while 15 X-ray/radio associations do not have an optical identification brighter than R=20.

Catalog Bibcode

2003MNRAS.342..575C

References

The BeppoSAX High Energy Large Area Survey (HELLAS).
VI. The radio properties.
    Ciliegi P., Vignali C., Comastri A., Fiore F., La Franca F., Perola G.C.
   <Mon. Not. R. Astron. Soc. 342, 575 (2003)>
   =2003MNRAS.342..575C
The BeppoSAX High Energy Large Area Survey (HELLAS)
V. The nature of the hard X-ray source population and its evolution.
    La Franca F., Fiore F., Vignali C., Antonelli A., Comastri A., Giommi P.,
    Matt G., Molendi S., Perola G.C., Pompilio F.
   <Astrophys. J. 570, 100 (2002)>
   =2002ApJ...570..100L
The BeppoSAX High Energy Large Area Survey (HELLAS).
II. Number counts and X-ray spectral properties.
    Fiore F., Giommi P., Vignali C., Comastri A., Matt G., Perola G.C.,
    La Franca F., Molendi S., Tamburelli F., Antonelli L.A.
   <Mon. Not. R. Astron. Soc. 327, 771 (2001)>
   =2001MNRAS.327..771F

Provenance

This table was created by the HEASARC in July 2014 based on CDS Catalog J/MNRAS/342/575 file table1.dat.

Parameters

HELLAS_ID
The unique BeppoSAX HELLAS source designation. This was not given in the original table but was taken by the HEASARC from table 2 of Fiore et al. (2001, MNRAS, 327, 771, available at the HEASARC as the SAXHELLAS table) which lists the same set of 147 X-ray sources.

Name
The BeppoSAX HELLAS source designation as recommended by the CDS Dictionary of Nomenclature of Celestial Objects, using the 'HELLAS' prefix (for High Energy Large Area Survey) and the source identification number, replacing the underscore ('_') character in some of the source numbers with a period ('.'). This was not given in the original table but was taken by the HEASARC from table 2 of Fiore et al. (2001, MNRAS, 327, 771, available at the HEASARC as the SAXHELLAS table) which lists the same set of 147 X-ray sources. HELLAS Identification Number

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 sexagesimal coordinates to a precision of 0.1 seconds of time in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 sexagesimal coordinates to a precision of 1 arcsecond in the original table. The HEASARC notes that the HELLAS source #124 has a J2000.0 Declination of -19^o 26' 19" which differs by 12 arcseconds from the corresponding value given in the SAXHELLAS table of -19^o 26' 31".

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Off_Axis
The off-axis angle of the X-ray source from the field center, in arcminutes.

Flux
The flux of the X-ray source in the 5-10 keV band, in erg cm^-2s^-1.

Rmag_Limit
This flag parameter is set to '>' if the corresponding R magnitude value is an upper limit in brightness rather than a detection.

Rmag
The R-band magnitude of the optical counterpart to the X-ray source, taken from La Franca et al. (2002, ApJ, 570, 100) unless otherwise specified by a non-blank value of the ref_rmag parameter (q.v.).

Ref_Rmag
This flag parameter is set to non-blank values in cases where the R magnitude is not taken from La Franca et al. (2002, ApJ, 570, 100), as follows:

        a = Magnitude from the APM (CDS Cat. <I/267>) catalog;
        l = Magnitude from Lehmann et al. 2000, A&A, 354, 35;
        u = Magnitude from the USNO (CDS Cat. <I/252>) catalog.

Source_Type
The spectroscopic identification of the optical counterpart for the X-ray source taken from La Franca et al. (2002, ApJ, 570, 100), as follows:

        1 = Type 1 AGN;
        2 = Type 2 AGN;
        3 = BL Lac;
        4 = Cluster of galaxies;
        5 = ELG (emission-line galaxy);
        6 = Radio galaxy.

Ref_Source_Type
This flag parameter is set to 'l' to indicate that the source type and redshift information come from Lehmann et al. (2000, A&A, 354, 35).

Redshift
The spectroscopic redshift of the optical counterpart for the X-ray source taken from La Franca et al. (2002, ApJ, 570, 100).

Flux_8p6_GHz_Limit
This flag parameter is set to '<' if the corresponding flux density value is an upper limit rather than a detection. For the X-ray sources without radio counterparts, the authors report the 3-sigma upper limit of their maps.

Flux_8p6_GHz
The flux density of the radio counterpart to the X-ray source (or upper limit thereof if the corresponding limit flag value is <') at 8.6 GHz (3 cm), in mJy.

Flux_8p6_GHz_Error
The rms uncertainty in the 8.6-GHz flux density of the radio counterpart to the X-ray source, in mJy.

Flux_8p6_GHz_Flag
This flag parameter is set to 'n' if the corresponding flux density value is taken from NED.

Flux_5_GHz_Limit
This flag parameter is set to '<' if the corresponding flux density value is an upper limit rather than a detection. For the X-ray sources without radio counterparts, the authors report the 3-sigma upper limit of their maps.

Flux_5_GHz
The flux density of the radio counterpart to the X-ray source (or upper limit thereof if the corresponding limit flag value is <') at 4.9 GHz (6 cm), in mJy.

Flux_5_GHz_Error
The rms uncertainty in the 4.9-GHz flux density of the radio counterpart to the X-ray source, in mJy.

Flux_5_GHz_Flag
This flag parameter is set to 'n' if the corresponding flux density value is taken from NED.

Flux_1p4_GHz_Limit
This flag parameter is set to '<' if the corresponding flux density value is an upper limit rather than a detection.

Flux_1p4_GHz
The flux density of the radio counterpart to the X-ray source (or upper limit thereof if the corresponding limit flag value is <') at 1.4 GHz (20 cm), in mJy. These data are taken from the NVSS and/or FIRST catalogs as discussed in the Overview above.

Flux_1p4_GHz_Error
The rms uncertainty in the 1.4-GHz flux density of the radio counterpart to the X-ray source, in mJy.

Flux_1p4_GHz_Flag
This flag parameter is set to 'n' if the corresponding flux density value is taken from NED.

Rad_Spectral_Index_Limit
This flag parameter is set to '<' or '>' if the corresponding spectral index values are upper or lower limits, respectively.

Rad_Spectral_Index
The radio spectral index of the X-ray source counterpart calculated using the available frequencies (mainly 6 and 20 cm).

Radio_RA
The Right Ascension of the radio counterpart to the X-ray source in the selected equinox. This was given in the original table in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time. The position of the radio sources is that obtained from the authors' 6-cm map (except when the source is detected only at 20 cm). The typical positional error of 6-cm sources is below 1 arcsecond.

Radio_Dec
The Declination of the radio counterpart to the X-ray source in the selected equinox. This was given in the original table in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds. The position of the radio sources is that obtained from the authors' 6-cm map (except when the source is detected only at 20 cm). The typical positional error of 6-cm sources is below 1 arcsecond.

Xray_Radio_Offset
The angular distance between the X-ray and radio source positions, in arcseconds.

XR_Random_Assoc_Prob
The probability of a random association between the X-ray and radio sources, P_xr, defined in Section 3 of the reference paper (Ciliegi et al. 2003, MNRAS< 342, 575)..

Radio_Optical_Offset
The angular distance between the radio and optical source positions, in arcseconds.

RO_Random_Assoc_Prob
The probability of a random association between the radio and optical sources, P_ro,

RO_Spectral_Index_Limit
This flag parameter is set to '<' or '>' if the corresponding spectral index values are upper or lower limits, respectively.

RO_Spectral_Index
The two-point radio-to-optical spectral index of the source, alpha_ro. This is defined as alpha_ro = log (F_5GHz/F₂₅₀₀)/5.38, where F_5GHz is the radio flux at 6 cm obtained from the present observation or by extrapolating the 20-cm flux density with a power-law slope with alpha_r = 0.7, and F₂₅₀₀ is the optical flux at 2500 Angstrom derived from the R magnitude with an optical slope of 0.5.

OX_Spectral_Index_Limit
This flag parameter is set to '<' or '>' if the corresponding spectral index values are upper or lower limits, respectively.

OX_Spectral_Index
The two-point radio-to-optical spectral index of the source, alpha_ox. This is defined as alpha_ox = log(F₂₅₀₀/F_2keV)/2.605, where F₂₅₀₀ is the optical flux at 2500 Angstrom derived from the R magnitude with an optical slope of 0.5, and F_2keV is the monochromatic X-ray flux at 2 keV derived from the measured BeppoSAX 5-10 keV flux and assuming an energy spectral index in t X-ray band of 0.6 (Fiore et al. 2001, MNRAS, 327, 771).

Class
The HEASARC Browse object classification of the source, based on the value of the source_type parameter.

Contact Person

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

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Last Modified: 15-Jul-2014

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Last Modified: 15-Jul-2014