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CHANTYPGPR - Chandra Typical Galactic Plane Region Point Source Catalog

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Overview

Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), the authors carried out a deep hard X-ray observation of the Galactic plane region at a location (l, b) ~ (28.5 degrees, 0.0 degrees), where no discrete X-ray source had been reported previously. They detected 274 new point X-ray sources (4-sigma or greater confidence in any of the 3 energy bands 0.5 - 3.0 keV, 3.0 - 8.0 keV or 0.5 - 8.0 keV), as well as strong Galactic diffuse emission within two partially overlapping ACIS-I fields (~ 250 square arcminutes in total). The point-source sensitivity was ~ 3 x 10^-15 ergs/s/cm^2 in the 2 - 10 keV band and ~ 2 x 10^-16 ergs/s/cm^2 in the 0.5 - 2 keV band The sum of all the detected point-source fluxes accounts for only ~ 10% of the total X-ray flux in the field of view. Only 26 point sources were detected in both the soft and hard bands, indicating that there are two distinct classes of X-ray source distinguished by their spectral hardnese ratios. The surface number density of the hard sources is only slightly higher than that measured in high Galactic latitude regions, indicating that the majority of the hard sources are background AGNs.

Following up the Chandra observation, the authors performed a near-infrared (NIR) survey with SofI at ESO/NTT. Almost all the soft X-ray sources have been identified in the NIR, and their spectral types are consistent with main-sequence stars, suggesting that most of them are nearby X-ray-active stars. On the other hand, only 22% of the hard sources had near-IR counterparts, which are presumably Galactic. From X-ray and near-IR spectral study, they are most likely to be quiescent cataclysmic variables.


Catalog Bibcode

2005ApJ...635..214E

References

Chandra deep X-ray observation of a typical galactic plane region and
near-infrared identification.
    Ebisawa K., Tsujimoto M., Paizis A., Hamaguchi K., Bamba A., Cutri R.,
    Kaneda H., Maeda Y., Sato G., Senda A., Ueno M., Yamauchi S., Beckmann V.,
    Courvoisier T.J.-L., Dubath P., Nishihara E.
   <Astrophys. J., 635, 214-242 (2005)>
   =2005ApJ...635..214E

Provenance

This Browse table was created by the HEASARC in December 2006 based on CDS Catalog J/ApJ/635/214/, the file table1.dat.

Parameters

Sequence_Number
A running sequential identification number in order of increasing J2000 Right Ascension. This can be used to construct an alternative name for an X-ray source in this catalog, using the prefix '[ETP2005] {X} ' followed by the sequence number of the source.

Name
The recommended designation for the X-ray source, using the prefix 'CXOGPE J' (for Chandra X-ray Observatory, Galactic Plane, Ebisawa') and the truncated J2000 coordinates of the source.

Source_Flag
This parameter is a flag for the X-ray source, where 'T' means that the source shows significant time variation, whereas 'E' means that the source is extended.

AO
The Chandra Announcement of Opportunity Cycle in which the source was detected: 1 for the AO-1 observation which was carried out in 2000 February 25 (obsid 900021) and 2 for the AO-2 observation carried out in 2001 May 20 (obsid 900125).

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000 coordinates to a precision of 0.01 seconds of time in the originating table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000 coordinates to a precision of 0.1 arcseconds in the originating table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The positional error of the X-ray source, in arcseconds. This is the statistical error calculated by wavdetect, and does not include any systematic errors.

FB_Count_Rate_SNR
The significance of the X-ray source in the total 0.5 - 8.0 keV band, in multiples of sigma.

SB_Count_Rate_SNR
The significance of the X-ray source in the soft 0.5 - 3.0 keV band, in multiples of sigma.

HB_Count_Rate_SNR
The significance of the X-ray source in the hard 3.0 - 8.0 keV band, in multiples of sigma.

FB_Count_Rate
The normalized count rate of the X-ray source in the total band (0.5 - 8.0 keV), in counts per second. This is the count rate expected if the source had been located at the ACIS-I aim point (the on-axis direction) and observed for a 100 ksec exposure.

SB_Count_Rate
The normalized count rate S of the X-ray source in the soft band (0.5 - 3.0 keV), in counts per second. This is the count rate expected if the source had been located at the ACIS-I aim point (the on-axis direction) and observed for a 100 ksec exposure.

HB_Count_Rate
The normalized count rate H of the X-ray source in the hard band (3.0 - 8.0 keV), in counts per second. This is the count rate expected if the source had been located at the ACIS-I aim point (the on-axis direction) and observed for a 100 ksec exposure.

Hardness_Ratio
The spectral hardness ratio, (H-S)/(H+S), of the X-ray source.

Hardness_Ratio_Error
The uncertainty in the spectral hardness ratio.

SB_Flux
The flux of the X-ray source in the `standard' soft band (0.5 - 2 keV), in erg/s/cm^2. Notice that the definition of the bands for the fluxes and count rates are slightly different. The technique with which the fluxes were calculated and the adopted spectral model parameters are discussed in Section 3.2 of the published paper.

HB_Flux
The flux of the X-ray source in the `standard' hard band (2 - 10 keV), in erg/s/cm^2. Notice that the definition of the bands for the fluxes and count rates are slightly different. The technique with which the fluxes were calculated and the adopted spectral model parameters are discussed in Section 3.2 of the published paper.

Near_IR_Name
The near-IR counterpart to the X-ray source which is within 1" from the Chandra position, either from follow-up observations made with the SofI infrared camera on the New Technology Telescope (NTT) at the European Southern Observatory (ESO), or, for Chandra sources outside of the SofI fields, the 2MASS Survey. A near-IR name of the form 'SNNNNNN' indicates a SofI ID while one of the form 'JHHMMSSss+DDMMSSs' means a 2MASS ID. A value of 'No' means that the source is in the SOFI field of view, but that there are no SOFI counterparts, while a value of 'OoF' means that the source is out of the SOFI field, and has no 2MASS counterparts. Notice that, given the SofI source number density of ~0.03 sources per square arcsecond and the 1" arcsecond matching radius used, there is a 10% chance that any Chandra source will have an accidental SofI counterpart.

Offset
The positional offset between the X-ray source and the near-IR counterpart, in arcseconds.

Jmag
The J-band magnitude of the near-IR counterpart to the X-ray source. 2MASS magnitudes are used for stars brighter than 10th magnitude, since SofI starts to saturate for sources < 10 magnitudes (see Fig. 5 in the published paper). A value of 99.99 indicates that the source was not detected in this band.

Hmag
The H-band magnitude of the near-IR counterpart to the X-ray source. 2MASS magnitudes are used for stars brighter than 10th magnitude, since SofI starts to saturate for sources < 10 magnitudes (see Fig. 5 in the published paper). A value of 99.99 indicates that the source was not detected in this band.

Ks_Mag
The K_s-band magnitude of the near-IR counterpart to the X-ray source. 2MASS magnitudes are used for stars brighter than 10th magnitude, since SofI starts to saturate for sources < 10 magnitudes (see Fig. 5 in the published paper). A value of 99.99 indicates that the source was not detected in this band.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 6-Dec-2006