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AEGISX - AEGIS-X Chandra Extended Groth Strip X-Ray Point Source Catalog

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Overview

This table contains the X-ray sources detected in the AEGIS-X survey, a series of deep Chandra ACIS-I observations of the Extended Groth Strip (EGS). The survey comprises pointings at eight separate positions, each with nominal exposure of 200 ks, covering a total area of approximately 0.67 deg2 in a strip of length 2 degrees. In their paper, the authors describe in detail an updated version of the data reduction and point-source-detection algorithms used to analyze these data. A total of 1325 band-merged sources have been found to a Poisson probability limit of 4 x 10-6, with limiting fluxes of 5.3 x 10-17 erg cm-2 s-1 in the soft (0.5 - 2 keV) band and 3.8 x 10-16 erg cm-2 s-1 in the hard (2 - 10 keV) band. They present simulations verifying the validity of their source-detection procedure and showing a very small, <1.5%, contamination rate from spurious sources. Optical/NIR counterparts have been identified from the DEEP2, CFHTLS, and Spitzer/Infrared Array Camera (IRAC) surveys of the same region. Using a likelihood ratio method, they find optical counterparts for 76% of their sources, complete to R_AB = 24.1, and, of the 66% of the sources that have IRAC coverage, 94% have a counterpart to a limit of 0.9 uJy at 3.6 um (m_AB = 23.8). After accounting for (small) positional offsets in the eight Chandra fields, the astrometric accuracy of Chandra positions is found to be 0.8 arseconds rms; however, this number depends both on the off-axis angle and the number of detected counts for a given source.

The AEGIS-X source catalog is publicly available in FITS table format at http://astro.imperial.ac.uk/research/aegis/cats.shtml. The FITS version of the catalog includes more information about the sources, such as the Poisson probability, counts, PSF size, and exposure value in each of the bands. Postage stamp images of the sources are also available.


Catalog Bibcode

2009ApJS..180..102L

References

AEGIS-X: the Chandra Deep Survey of the Extended Groth Strip
    Laird E.S., Nandra K., Georgakakis A., Aird J.A., Barmby P.,
    Conselice C.J., Coil A.L., Davis M., Faber S.M., Fazio G.G.,
    Guhathakurta P., Koo D.C., Sarajedini V., Willmer C.N.A.
   <Astrophys. J. Suppl. 180, 102-116 (2009)
   =2009ApJS..180..102L

Provenance

This table was created by the HEASARC in February 2009 based on the electronic versions of Tables 9, 10 and 11 from the paper which were obtained from the strophysical Journal web site.

Parameters

Source_ID
The X-ray source identifier using the 'egs' prefix for Extended Groth Strip and a source number in order of increasing J2000.0 Right Ascension.

Field_ID
The field identifier for the X-ray source, which indicates the individual field in which the source was detected (see Section 2.1 of the reference paper for further information on the field definitions).

Name
The Chandra X-ray Observatory (CXO) X-ray designation, using the standard 'CXOU J' prefix and the J2000.0 equatorial source position.

RA
The Right Ascension of the Chandra X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-6 degrees (0.0036 arcseconds) in the original table. These coordinates have been shifted to agree with the Sloan Digital Sky Survey (SDSS) reference frame of the DEEP2 images: the positional offsets applied to each field are listed in Table 3 of the reference paper.

Dec
The Declination of the Chandra X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-6 degrees (0.0036 arcseconds) in the original table. These coordinates have been shifted to agree with the Sloan Digital Sky Survey (SDSS) reference frame of the DEEP2 images: the positional offsets applied to each field are listed in Table 3 of the reference paper.

LII
The Galactic Longitude of the Chandra X-ray source.

BII
The Galactic Latitude of the Chandra X-ray source.

Error_Radius
The X-ray source one-sigma positional error, in arcseconds.

Off_Axis
The X-ray source off-axis angle, in arcminutes.

FB_Counts
The X-ray source full-band (0.5 - 7 keV) counts. Counts are given regardless of whether a source was detected in the band.

FB_Bck_Counts
The expected full-band (0.5 - 7 keV) background counts within the X-ray source extraction region.

SB_Counts
The X-ray source soft-band (0.5 - 2 keV) counts. Counts are given regardless of whether a source was detected in the band.

SB_Bck_Counts
The expected soft-band (0.5 - 2 keV) background counts within the X-ray source extraction region.

HB_Counts
The X-ray source hard-band (2 - 7 keV) counts. Counts are given regardless of whether a source was detected in the band.

HB_Bck_Counts
The expected hard-band (2 - 7 keV) background counts within the X-ray source extraction region.

UHB_Counts
The X-ray source ultra-hard-band (4 - 7 keV) counts. Counts are given regardless of whether a source was detected in the band.

UHB_Bck_Counts
The expected ultra-hard-band (4 - 7 keV) background counts within the X-ray source extraction region.

Detect_Bands
The bands in which the source is detected with Poisson false-detection probability < 4 x 10-6, where the bands are full (f), soft (s), hard (h), and ultra-hard (u).

Min_Detect_Prob
The lowest false detection probability found for the X-ray source in the four energy bands; probabilities lower than 10-8 are quoted as 10-8.

Source_Flag
This flag parameter is set to 'a' if the Bayesian X-ray fluxes in the detected bands were calculated from the 70% encircled energy fraction (EEF) rather than the usual 90% EEF.

Bayes_FB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 1-sigma, or 68%, upper limits.

Bayes_FB_Flux
The standard full-band (0.5 - 10 keV) X-ray source flux, in erg s-1 cm-2, calculated using the Bayesian method described in Section 3.3 of the reference paper, which corrects for the Eddington bias. In three cases (source_id values egs_0367, egs_0457, and egs_0633), sources that were significantly detected in a band had best estimate fluxes of zero, using the Bayesian method. This discrepancy arises due to the different EEFs used for the photometry (90% EEF) and for the detection (70% EEF). In these cases, the authors use source and background counts corresponding to the 70% EEF area to calculate the fluxes in the detected bands. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible.

Bayes_FB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_FB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_SB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 1-sigma, or 68%, upper limits.

Bayes_SB_Flux
The standard soft-band (0.5 - 2 keV) X-ray source flux, in erg s-1 cm-2, calculated using the Bayesian method described in Section 3.3 of the reference paper, which corrects for the Eddington bias. In three cases (source_id values egs_0367, egs_0457, and egs_0633), sources that were significantly detected in a band had best estimate fluxes of zero, using the Bayesian method. This discrepancy arises due to the different EEFs used for the photometry (90% EEF) and for the detection (70% EEF). In these cases, the authors use source and background counts corresponding to the 70% EEF area to calculate the fluxes in the detected bands. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible.

Bayes_SB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_SB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_HB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 1-sigma, or 68%, upper limits.

Bayes_HB_Flux
The standard hard-band (2 - 10 keV) X-ray source flux, in erg s-1 cm-2, calculated using the Bayesian method described in Section 3.3 of the reference paper, which corrects for the Eddington bias. In three cases (source_id values egs_0367, egs_0457, and egs_0633), sources that were significantly detected in a band had best estimate fluxes of zero, using the Bayesian method. This discrepancy arises due to the different EEFs used for the photometry (90% EEF) and for the detection (70% EEF). In these cases, the authors use source and background counts corresponding to the 70% EEF area to calculate the fluxes in the detected bands. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible.

Bayes_HB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_HB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_UHB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 1-sigma, or 68%, upper limits.

Bayes_UHB_Flux
The standard ultra-hard-band (5 - 10 keV) X-ray source flux, in erg s-1 cm-2, calculated using the Bayesian method described in Section 3.3 of the reference paper, which corrects for the Eddington bias. In three cases (source_id values egs_0367, egs_0457, and egs_0633), sources that were significantly detected in a band had best estimate fluxes of zero, using the Bayesian method. This discrepancy arises due to the different EEFs used for the photometry (90% EEF) and for the detection (70% EEF). In these cases, the authors use source and background counts corresponding to the 70% EEF area to calculate the fluxes in the detected bands. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible.

Bayes_UHB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_UHB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

FB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 99% upper limits, notice, not 68% ones as for the Bayesian fluxes.

FB_Flux
The observed-frame standard full-band (0.5 - 10 keV) X-ray source flux, in erg s-1 cm-2, obtained using the 'classical method'. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible.

FB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

FB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

SB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 99% upper limits, notice, not 68% ones as for the Bayesian fluxes.

SB_Flux
The observed-frame standard soft-band (0.5 - 2 keV) X-ray source flux, in erg s-1 cm-2, obtained using the 'classical method'. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible

SB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

SB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

HB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 99% upper limits, notice, not 68% ones as for the Bayesian fluxes.

HB_Flux
The observed-frame standard hard-band (2 - 10 keV) X-ray source flux, in erg s-1 cm-2, obtained using the 'classical method'. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible

HB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

HB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

UHB_Flux_Limit
This parameter is set to '<' if the associated flux is an upper limit rather than a measured value. The limits are 99% upper limits, notice, not 68% ones as for the Bayesian fluxes.

UHB_Flux
The observed-frame standard ultra-hard-band (5 - 10 keV) X-ray source flux, in erg s-1 cm-2, obtained using the 'classical method'. All the fluxes have not been corrected for Galactic or intrinsic source absorption. To correct for Galactic absorption the full- and soft-band fluxes should be increased by 2% and 4.2%, respectively. The corrections to the hard and ultra-hard fluxes are negligible

UHB_Flux_Pos_Err
The upper 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

UHB_Flux_Neg_Err
The lower 1-sigma error in the associated flux parameter, in erg s-1 cm-2.

Bayes_HR
The X-ray source hardness ratio calculated using the Bayesian method.

Bayes_HR_Pos_Err
The upper 1-sigma error in the Bayesian hardness ratio.

Bayes_HR_Neg_Err
The lower 1-sigma error in the Bayesian hardness ratio

Hardness_Ratio
The X-ray source hardness ratio HR calculated using the classical method. For sources only detected in the full band, and with upper limits in both hard and soft bands, the classical HR cannot be determined and is set to -99.00.

Quality_Flag
This parameter contains a flag for the quality of the X-ray photometry. A flag value of '1' indicates the presence of a nearby source that may be contaminating the photometry. A flag value of '2' indicates that another source was detected with the 90% EEF and that the photometry is likely heavily contaminated and the source position uncertain (see Section 3.3 of the reference paper). All other sources have a flag value of 0'.

Opt_IR_Match_Flag
This parameter can contain a coded flag for the source matching details as follows:

   a = Bright, resolved galaxies that are clearly present in the CFHTLS i'
        imaging but have been excluded from CFHTLS catalog for unknown reason.
   b = Bright IRAC sources, without secure optical counterpart listed in the
        table, that have been excluded from Figure 9. Clear, very bright optical
        counterparts exist, but are excluded from DEEP2 catalog.
  

Rmag_Limit
This parameter is set to '>' if the associated magnitude is a lower (bright) limit rather than a measured value.

Rmag
The R-band magnitude of the DEEP2 counterpart, for every X-ray source with a secure DEEP2 counterpart. If optical or IR coverage exists but no secure counterpart was detected, then an upper limit for the magnitude is given, whereas X-ray sources with no optical or IR coverage are left blank.

DEEP2_CXO_Offset
The positional offset, in arcseconds, between the DEEP2 optical counterpart and the Chandra X-ray source position.

DEEP2_Likelihood
The likelihood ratio LR for the DEEP2 counterpart to the Chandra X-ray source. For both the DEEP2 and CFHTLS surveys, the authors consider counterparts with LR > 0.5 as secure, giving a ~6% contamination rate in both cases.

DEEP2_ID
The DEEP2 counterpart ID number (see Coil et al. 2004, ApJ, 617, 765).

Imag_Limit
This parameter is set to '>' if the associated magnitude is a lower (bright) limit rather than a measured value.

Imag
The i-prime (i') band AB magnitude of the CHFTLS counterpart, for every X-ray source with a secure CFHTLS counterpart. If optical or IR coverage exists but no secure counterpart was detected, then an upper limit for the magnitude is given, whereas X-ray sources with no optical or IR coverage are left blank.

CFHTLS_CXO_Offset
The positional offset, in arcseconds, between the CFHTLS optical counterpart and the Chandra X-ray source position.

CFHTLS_Likelihood
The likelihood ratio LR for the CFHTLS counterpart to the Chandra X-ray source. For both the DEEP2 and CFHTLS surveys, the authors consider counterparts with LR > 0.5 as secure, giving a ~6% contamination rate in both cases.

CFHTLS_ID
The CFHTLS counterpart ID number (see http://terapix.iap.fr/article.php?id_article=556).

IRAC_3p6_um_Mag_Limit
This parameter is set to '>' if the associated magnitude is a lower (bright) limit rather than a measured value.

IRAC_3p6_um_Mag
The 3.6-um magnitude of the Spitzer IRAC counterpart, for each source with a secure IRAC counterpart. If optical or IR coverage exists but no secure counterpart was detected, then an upper limit for the magnitude is given, whereas X-ray sources with no optical or IR coverage are left blank.

IRAC_CXO_Offset
The positional offset, in arcseconds, between the IRAC infrared counterpart and the Chandra X-ray source position.

IRAC_Likelihood
The likelihood ratio LR for the IRAC counterpart to the Chandra X-ray source. A total of 882 Chandra sources are covered by the Spitzer region. Using the maximum likelihood method, and considering only matches with LR > 0.5, the authors find that 830 (94.1%) have secure 3.6-um counterparts. This cut on LR gives a ~ 1% spurious counterpart rate.

IRAC_ID
The truncated IRAC object 3.6-micron identification of the counterpart to the X-ray source, from Barmby et al. (2008, ApJS, 177, 431). The complete IRAC name of the object should be preceded by a prefix of 'EGSIRAC '.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 12-Feb-2009