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ECDFSCXO - Extended Chandra Deep Field-South X-Ray Point Source Catalog

HEASARC
Archive

Overview

The Extended Chandra Deep Field-South (ECDFS) survey consists of four Chandra X-Ray Observatory (CXO) ACIS-I pointings and covers ~1100 arcmin2 (~0.3 deg2) centered on the original CDF-S field to a depth of approximately 228 ks. This is the largest Chandra survey ever conducted at such depth, and only one XMM-Newton survey reaches a lower flux limit in the hard 2.0-8.0 keV band. The authors detect 651 unique sources: 587 using a conservative source-detection threshold (identified by source_type = 'P' for primary source) and 64 (identified by source_type = 'S' for secondary source) using a lower source-detection threshold. These are combined in this HEASARC representation but were presented as two separate catalogs (Table 4 contained the primary sources, and Table 5 the secondary sources) in the original reference paper. Of the 651 total sources, 561 are detected in the full 0.5-8.0 keV band, 529 in the soft 0.5-2.0 keV band, and 335 in the hard 2.0-8.0 keV band. For point sources near the aim point, the limiting fluxes are approximately 1.7 x 10-16 and 3.9 x 10-16 ergs/cm2/s in the 0.5-2.0 and 2.0-8.0 keV bands, respectively. In their paper, the authors present the differential and cumulative flux distributions, which are in good agreement with the number counts from previous deep X-ray surveys and with the predictions from an active galactic nucleus (AGN) population synthesis model that can explain the X-ray background. In general, fainter sources have harder X-ray spectra, consistent with the hypothesis that these sources are mainly obscured AGNs.

All nine observations of the ECDFS survey field were conducted with the Advanced CCD Imaging Spectrometer (ACIS) on board Chandra as part of the approved guest observer program in Cycle 5.

Notice that Lehmer et al. (2005, ApJS, 161, 21) conducted a somewhat different analysis on these same data and obtained similar, but not identical results, e.g., Lehmer et al. found 809 total X-ray sources compared to 651 in the present table.


Catalog Bibcode

2006AJ....131.2373V

References

The extended Chandra Deep Field-South survey: X-ray point-source catalog.
    Virani S.N., Treister E., Urry C.M., Gawiser E.
   <Astron. J., 131, 2373-2382 (2006)>
   =2006AJ....131.2373V

Provenance

This table was created by the HEASARC in April 2009 based on the electronic versions of Tables 4 and 5 from the paper which were obtained from the CDS (their catalog J/AJ/131/2373 files table4.dat and table5.dat).

HEASARC Implementation

This HEASARC table contains 651 unique sources: 587 X-ray sources found using a conservative source-detection threshold which had a false-positive probability threshold p_thresh of 1 x 10-7 in at least one of the three standard bands (identified by the HEASARC-created parameter of source_type = 'P' for primary source) and 64 additional sources (identified by source_type = 'S' for secondary source) obtained using a lower source-detection threshold of 1 x 10-6 ^. These are combined in this HEASARC representation but were presented as two separate catalogs (Table 4 contained the primary sources, and Table 5 the secondary sources) in the original reference paper. Tables 4 and 5 from the reference paper (and thus this HEASARC table based on them) exclude sources found by wavdetect in which one or both of the axes of the "source ellipse" collapsed to zero. Over the survey field, there were 70 such sources (listed in Table 6 of the reference paper, but not included in this HEASARC table): in general, these are unusual sources, and although their formal probablility of being spurious was low, there may have been problems with these detections.

Parameters

Source_Number
A sequential unique identification number for each X-ray source in this catalog, with source numbers from 1 to 587, inclusive, being the primary sources (Table 4 of the reference paper) and those from 588 to 651, inclusive, being the secondary sources (Table 5 of the reference paper). The HEASARC notes that the source numbers shown in the sample versions of these two tables in the published version of the paper disagree with (and apparently have been superseded by) those in the machine-readable version of the tables that were archived with the CDS (used as the basis of this HEASARC table).

Name
The source number-based designation for the X-ray source, in the form '[VTU2006] NNN', where VTU2006 refers to the authors (Virani, Treister, Urry) and the publication date, and NNN is the source number.

Source_Type
This HEASARC-created flag parameter indicates whether the source is primary ('P') or secondary ('S'), as discussed in more detail in the HEASARC_Implementation section above.

Alt_Name
The International Astronomical Union-style J2000.0 position-based names for the X-ray sources in this catalog. All source names begin with the acronym "CXOYECDF" (for "CXO Yale Extended Chandra Deep Field south").

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original tables. The X-ray positions are wavdetect-determined positions for the unbinned images. If a source is detected in multiple bands, then the authors quote the position determined in the full band; when a source is not detected in the full band, they quote the soft-band position or the hard-band position.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original tables. The X-ray positions are wavdetect-determined positions for the unbinned images. If a source is detected in multiple bands, then the authors quote the position determined in the full band; when a source is not detected in the full band, they quote the soft-band position or the hard-band position.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

PSF_Size
The point-spread function (PSF) cell size, in units of arcseconds, as determined by wavdetect. The farther off-axis a source lies, the larger the PSF size is.

FB_Count_Rate
The source count rate (in counts s-1) in the full band (0.5-8.0 keV) derived using the appropriate band exposure map. The count rates are exposure- and contamination-corrected. If a source is undetected in a given band, no count rate is tabulated.

FB_Count_Rate_High_Bound
The upper bound to the corresponding count rate estimated according to the prescription of Gehrels (1986, ApJ, 303, 336).

FB_Count_Rate_Low_Bound
The lower bound to the corresponding count rate estimated according to the prescription of Gehrels (1986, ApJ, 303, 336).

SB_Count_Rate
The source count rate (in counts s-1) in the soft band (0.5-2.0 keV) derived using the appropriate band exposure map. The count rates are exposure- and contamination-corrected. If a source is undetected in a given band, no count rate is tabulated.

SB_Count_Rate_High_Bound
The upper bound to the corresponding count rate estimated according to the prescription of Gehrels (1986, ApJ, 303, 336).

SB_Count_Rate_Low_Bound
The lower bound to the corresponding count rate estimated according to the prescription of Gehrels (1986, ApJ, 303, 336).

HB_Count_Rate
The source count rate (in counts s-1) in the hard band (2.0-8.0 keV) derived using the appropriate band exposure map. The count rates are exposure- and contamination-corrected. If a source is undetected in a given band, no count rate is tabulated.

HB_Count_Rate_High_Bound
The upper bound to the corresponding count rate estimated according to the prescription of Gehrels (1986, ApJ, 303, 336).

HB_Count_Rate_Low_Bound
The lower bound to the corresponding count rate estimated according to the prescription of Gehrels (1986, ApJ, 303, 336).

FB_Flux
The full-band flux (in units of ergs cm-2 s-1) calculated from the corresponding count rate and assuming a photon slope of power-law index Gamma = 1.4 corrected for Galactic absorption. If a source was undetected in the full band but was detected in the hard or soft band, the hard- or soft-band flux (in that order of priority) was used to extrapolate to the full band assuming a photon slope of 1.4.

SB_Flux
The soft-band flux (in units of ergs cm-2 s-1) calculated from the corresponding count rate and assuming a photon slope of power-law index Gamma = 1.4 corrected for Galactic absorption. If a source was undetected in the soft band but was detected in the full or hard band, the full- or hard-band flux (in that order of priority) was used to extrapolate to the soft band assuming a photon slope of 1.4.

HB_Flux
The hard-band flux (in units of ergs cm-2 s-1) calculated from the corresponding count rate and assuming a photon slope of power-law index Gamma = 1.4 corrected for Galactic absorption. If a source was undetected in the hard band but was detected in the full or soft band, the full- or soft-band flux (in that order of priority) was used to extrapolate to the hard band assuming a photon slope of 1.4.

Source_Notes
This parameters contains individual notes for each source. Examples include the A03 catalog ID number (with a "c" prefix, e.g., "c15") if the source was detected in the CDF-S by Alexander et al. (2003, AJ, 126, 539), or values indicating if the source was selected from a band other than the full band ("h" or "s"), or was only detected in the full band ("f").


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 17-Apr-2009