LEDAS  
Leicester Database and Archive Service
 
ARNIE Index
ARNIE Help
ARNIE Tutorial
Search...
All databases
All helpfiles
Line
Footer
E-mail

EROSXMM: Help

EROSXMM - Extremely Red Objects XMM-Newton Survey Catalog


Overview

This table contains the results of a deep (about 80 ks) XMM-Newton survey of the largest sample of near-infrared-selected Extremely Red Objects (R-K > 5) available to date to K_s < ~19.2. At the relatively bright X-ray fluxes ((F(2-10 keV) >~ 4 x 10^-15 erg cm^-2 s^-1) and near-infrared magnitude probed by the present observations, the fraction of AGN (i.e. X-ray detected) among the ERO population is small (~3.5%); conversely, the fraction of EROs among hard X-ray selected sources is much higher (~20%). The X-ray properties of the 9 EROs detected in this XMM-Newton observation indicate absorption in excess of 10^22 cm^-2 in a large fraction of them. The X-ray, optical and near-infrared properties of those X-ray selected EROs with a spectroscopic or photometric redshift nicely match those expected for type 2 quasars, the high-luminosity, high-redshift obscured AGNs predicted in baseline XRB synthesis models. A close correlation is detected between X-ray and K-band fluxes.

This table contains the X-ray and optical information for the sources detected in the sum of 3 separate XMM-Newton observations of a field centered on 14 49 25, +09 00 13 (J2000.0 RA and Dec) known as the "Daddi" field (Daddi et al. 2000, A&A, 361, 535) in which 257 EROs are known to be present. The data from all 3 EPIC instruments (PN, MOS1 and MOS2) obtained in the 3 observations was combined, yielding a total exposure time for the PN of ~82 ks, and for the MOS instruments of ~78 ks. The X-ray hardness ratio (HR) and the optical to near-infrared color (R and K magnitudes) are reported for all the detected X-ray sources and their counterparts, along with the reliability of the X-ray to optical or near-infrared associations as measured by the likelihood ratios, LR(R) and LR(K). This table lists data for the 111 proposed optical/infrared counterparts for the 97 detected X-ray sources, i.e., X-ray sources with more than one possible optical/IR counterpart will have multiple entries in this table, one for each counterpart, as follows: 73 X-ray sources have secure optical/near-IR counterparts (counterpart_status=1), 7 X-ray sources have 2 possible 'likely' counterparts, and 1 X-ray source has 3 such counterparts (counterpart_status=2), 6 X-ray sources have only low-likelihood counterparts all of which lie outside the 3" matching radii (counterpart_status=3), and the remaining 9 X-ray sources lack optical and infrared photometry (counterpart_status=4).


Catalog Bibcode

2005A&A...432...69B

References

XMM-Newton observations of Extremely Red Objects and the link with luminous,
X-ray obscured quasars.
    Brusa M., Comastri A., Daddi E., Pozzetti L., Zamorani G., Vignali C.,
    Cimatti A., Fiore F., Mignoli M., Ciliegi P., Rottgering H.J.A.
   <Astron. Astrophys. 432, 69 (2005)>
   =2005A&A...432...69B

Provenance

This table was created by the HEASARC in February 2007 based on the CDS Catalog J/A+A/432/69 files table1.dat and table2.dat.

Parameters

Source_Number
A unique X-ray source identifier, apparently from the source detection algorithm. Since only sources which were detected above a detection probability threshold of 2 x 10^-5 (which corresponds to less than 1 spurious X-ray source, or a ~4-sigma Gaussian threshold) were retained in the final list, the source numbers for the 87 X-ray sources are not contiguous, but range from 23 to 370.

Name
The name for the X-ray source using the '[BCD2005]' prefix (for Brusa, Comastri and Daddi 2005) and the source number value, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the X-ray source centroid in the selected equinox. This was given in J2000.0 decimal degree coordinates to a precision of 10^-5 degrees in Table 1 of the reference paper. The X-ray centroids were astrometrically calibrated with respect to the optical positions of three bright quasars in the field: the resulting shift of ~2" (including a shift of +1.47" in RA) was applied to all the source positions.

Dec
The Declination of the X-ray source centroid in the selected equinox. This was given in J2000.0 decimal degree coordinates to a precision of 10^-5 degrees in Table 1 of the reference paper. The X-ray centroids were astrometrically calibrated with respect to the optical positions of three bright quasars in the field: the resulting shift of ~2" (including a shift of -1.29" in Declination) was applied to all the source positions.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

HB_Flux
The hard-band (2 - 10 keV) X-ray flux of the source, in erg/cm^2/s. The count rate to flux conversion factor was derived assuming a power law with a photon index Gamma of 1.7, absorbed by the Galactic column density in the direction of the Daddi field N_H of 5 x 10^20 atoms cm^-2 (Dickey and Lockman 1990, ARA&A, 28, 215), and weighted by the effective exposure times of the different EPIC cameras. The uncertainty in the derived fluxes is <15% for Delta(Gamma) = +/- 0.5 and N_H up to 10^21 atoms cm^-2. The corresponding full-band limiting flux is ~2 x 10^-15 erg/cm^2/s at the aim point and is a factor of ~1.5 times higher at the edge of the selected area, where the net exposure is ~40 ks. If the source was not detected in this band, no value is given for this flux.

HB_Counts_Limit
This parameter is set to '<' if the source was not detected in the hard band.

HB_Counts
The X-ray source counts in the hard band (2 - 10 keV), or the 3-sigma upper limit if the source was not detected in this band, i.e., if the corresponding limit parameter value is '<'.

HB_Counts_Error
The rms uncertainty in the X-ray source hard counts.

SB_Flux
The soft-band (0.5 - 2 keV) X-ray flux of the source, in erg/cm^2/s. The count rate to flux conversion factor was derived assuming a power law with a photon index Gamma of 1.7, absorbed by the Galactic column density in the direction of the Daddi field N_H of 5 x 10^20 atoms cm^-2 (Dickey and Lockman 1990, ARA&A, 28, 215), and wighted by the effective exposure times of the different EPIC cameras. The uncertainty in the derived fluxes is <15% for Delta(Gamma) = +/- 0.5 and N_H up to 10^21 atoms cm^-2. The corresponding full-band limiting flux is ~2 x 10^-15 erg/cm^2/s at the aim point and is a factor of ~1.5 times higher at the edge of the selected area, where the net exposure is ~40 ks. If the source was not detected in this band, no value is given for this flux.

SB_Counts_Limit
This parameter is set to '<' if the source was not detected in the soft band.

SB_Counts
The X-ray source counts in the soft band (0.5 - 2 keV), or the 3-sigma upper limit if the source was not detected in this band, i.e., if the corresponding limit parameter value is '<'.

SB_Counts_Error
The rms uncertainty in the X-ray source soft counts.

Counterpart_Status
The reliability status of the association of the optical/IR object with the X-ray source, coded as follows:

  1 = sources with secure X-ray to optical associations
  2 = sources with ambiguous X-ray to optical associations
  3 = sources with low X-ray to optical likelihood ratio
  4 = sources without optical/near infrared photometry
  

The methodology used to estimate the counterpart status is discussed in Section 2.4 of the reference paper. Of the 111 proposed optical/infrared counterparts for the 97 detected X-ray sources, i.e., X-ray sources with more than one possible optical/IR counterpart will have multiple entries in this table, one for each counterpart, as follows: 73 X-ray sources have secure optical/near-IR counterparts (counterpart_status=1), 7 X-ray sources have 2 possible 'likely' counterparts, and 1 X-ray source has 3 such counterparts (counterpart_status=2), 6 X-ray sources have only low-likelihood counterparts all of which lie outside the 3" matching radii (counterpart_status=3), and the remaining 9 X-ray sources lack optical and infrared photometry (counterpart_status=4).

Offset
The angular offset between the possible optical/IR counterpart and the X-ray source, in arcseconds.

Rmag
The R-band magnitude (in the AB system) of the possible optical/IR counterpart to the X-ray source detected within a radius of 3" around the X-ray source.

Kmag_Limit
This parameter is set to '<' if the K magnitude is an upper limit.

Kmag
The K-band magnitude (in the AB system) of the possible optical/IR counterpart to the X-ray source detected within a radius of 3" around the X-ray source.

R_Band_Likelihood
The likelihood ratio LR(R) in the R-band, defined as the ratio of the probablity that the optical/IR source is the correct identification for the x-ray source to the corresponding probability that it is an unrelated background object. This should be compared with the threshold value LR_th(R) = 0.25 which discriminates between spurious (<0.25) and real (>0.25) identifications (see Section 2.3 of the reference paper for more details).

K_Band_Likelihood
The likelihood ratio LR(K) in the K-band, defined as the ratio of the probablity that the optical/IR source is the correct identification for the x-ray source to the corresponding probability that it is an unrelated background object. This should be compared with the threshold value LR_th(K) = 0.25 which discriminates between spurious (<0.25) and real (>0.25) identifications (see Section 2.3 of the reference paper for more details).


Contact Person

Questions regarding the EROSXMM database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
HOME
SEARCH
SERVICES INFO SOFTWARE ViZieR BLASTA DSS
ARCHIVES ASCA CHANDRA GINGA ROSAT ARNIE