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L1641IOXMM - Lynds 1641 and iota Ori Region XMM-Newton X-Ray Point Source Catalog

HEASARC
Archive

Overview

This table contains results from an XMM-Newton and Spitzer survey of the part of the Orion A cloud south of the Orion Nebula, the 'Survey of Orion A with XMM-Newton and Spitzer (SOXS)'. The goal of SOXS is to detect the relatively bright X-ray sources in the Orion A cloud and complete the census of more evolved YSOs in this region. These stars represent a sample of cloud members chosen with minimal a priori bias toward their IR properties. This XMM-Newton survey includes the Lynds 1641 (L1641) dark cloud, a region of the Orion A cloud with very few massive stars and hence a relatively low ambient UV flux, and the region around the O9 III star iota Orionis. In addition to proprietary data, the authors used archival XMM data of the Orion Nebula Cluster (ONC) to extend their analysis to a major fraction of the Orion A cloud. They have detected 1060 X-ray sources with more than 4.5-sigma significance in L1641 and the iota Ori region. About 94% of the sources have Two Micron All Sky Survey (2MASS) and Spitzer counterparts, 204 and 23 being Class II and Class I or protostar objects, respectively. In addition, the authors have identified 489 X-ray sources as counterparts to Class III candidates, given they are bright in X-rays and appear as normal photospheres at mid-IR wavelengths. The remaining 205 X-ray sources are likely distant active galactic nuclei (AGN) or other galactic sources not related to Orion A. The authors find that Class III candidates appear more concentrated in two main clusters in L1641. The first cluster of Class III stars is found toward the northern part of L1641, concentrated around iota Ori. The stars in this cluster are more evolved than those in the Orion Nebula. The authors estimate a distance of 300-320 pc for this cluster showing that it is in the foreground of the Orion A cloud. Another cluster rich in Class III stars is located in L1641 South and appears to be a slightly older cluster embedded in the Orion A cloud. Furthermore, other evolved Class III stars are found north of the ONC toward NGC 1977.

The SOXS survey is composed of seven specifically proposed ~ 50 ks XMM-Newton fields, south of the ONC, to which the authors added four archival fields in the same region. The archival fields are centered on iota Orionis, V380 Ori, and V883 Ori, respectively (see Fig. 1 and Table 1 of the reference paper for more details of the X-ray observations).

This HEASARC table contains the contents of Table 2 (1060 X-ray detected sources in the fields S1 - S10 listed in Table 1 of the reference paper), Table 3 (best-fit spectral parameters for the 232 brightest of these X-ray sources) and Table 4 (list of 1041 IR counterparts to the X-ray sources) from the reference paper. Some X-ray sources have no identified counterparts (16 of them in fact lie outside of the FOV of the Spitzer observations), most have a single counterpart, and a small number have 2 or even 3 IR counterparts within the 5 arcseconds matching radius used. For X-ray sources with more than 1 IR counterpart, we have added entries for the additional counterparts (71 in total), repeating the X-ray information in such cases. Thus, this HEASARC table contains 1131 (1060 + 71) entries corresponding to the 1060 X-ray source detections. To make its contents easier to visualize, the HEASARC has added a a parameter ir_match which lists the counterpart number for the entry: If there is no identified IR counterpart, ir_match is set to 0, for the first listed IR counterpart to 1, for the second and third, to 2 and 3, respectively. Thus, if the user wants to reduce the table back to a pure list of X-ray sources and their primary IR counterparts, they should search the table selecting ir_match < 2.


Catalog Bibcode

2013ApJ...768...99P

References

An X-Ray Survey of the Young Stellar Population of the Lynds 1641 and Iota
Orionis Regions
     Pillitteri I., Wolk S.J., Megeath S.T., Allen L., Bally J., Gagne M.,
     Gutermuth R.A., Hartman L., Micela G., Myers P., and 5 coauthors
    <Astrophysical Journal, Volume 768, article id 99 (21pp) 2013>
    =2013ApJ...768...99P
Erratum: An X-Ray Survey of the Young Stellar Population of the Lynds 1641
and Iota Orionis Regions
     Pillitteri I., Wolk S.J., Megeath S.T., Allen L., Bally J., Gagne M.,
     Gutermuth R.A., Hartman L., Micela G., Myers P., and 5 coauthors
    <Astrophysical Journal, Volume 773, article id 80 (2pp) 2013>
    =2013ApJ...773...80P

Provenance

This table was created by the HEASARC in August 2013 based on the electronic versions of Tables 2 and 3 from the original reference paper (2013ApJ...768...99P) and Table 4 from the erratum (2013ApJ...773...80P), which were all obtained from the ApJ web site.

Parameters

Source_Number
A unique identification number for each XMM-Newton X-ray source in the catalog, in order of increasing J2000.0 Right Ascension. Note that to uniquely identify an entry in this table, since some X-ray sources have multiple entries corresponding to alternative IR counterparts, the user must specify both a source_number and an ir_match (q.v.) value.

Name
The XMM-Newton X-ray source designation, using the 'SOXS' prefix (for Survey of Orion A with XMM-Newton and Spitzer) and the X-ray source number, e.g., 'SOXS 1'.

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

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

LII
The Galactic Longitude of the XMM-Newton X-ray source.

BII
The Galactic Latitude of the XMM-Newton X-ray source.

Off_Axis
The off-axis distance of the XMM-Newton X-ray source from the aim point of the observation in which it was detected, in arcminutes.

Counts
The net total (summed MOS1 + MOS2 + PN) 0.3 - 8.0 keV counts in the XMM-Newton X-ray source.

Counts_Error
The uncertainty in the net total (summed MOS1 + MOS2 + PN) 0.3 - 8.0 keV counts in the XMM-Newton X-ray source.

Count_Rate
The count rate in the 0.3 - 8.0 keV band of the XMM-Newton X-ray source scaled to the MOS sensitivity, in counts/s (converted by the HEASARC from the counts/ks used in the original table).

Count_Rate_Error
The uncertainty in the count rate in the 0.3 - 8.0 keV band of the XMM-Newton X-ray source scaled to the MOS sensitivity, in counts/s (converted by the HEASARC from the counts/ks used in the original table).

Exposure
The sum of the exposure times from the 3 EPIC cameras (MOS1 + MOS2 + PN) for the X-ray source, in seconds (converted by the HEASARC from the ks units used in the original table).

ObsID
The XMM-Newton observation identifier of the observation in which the x-ray source was detected.

Spectral_Model
For sources with more than 500 total counts (232 out of 1060), as determined from the wavelet analysis software pwxdetect, spectra from MOS1, MOS2, and PN were grouped to have at least 25 counts per bin and fit simultaneously with XSPEC software V. 12.7 using one or two thermal APEC models (Smith et al. 1999, BAAS, 31, 735) with foreground absorption and with both fixed and varying metallicity (Z). The codes for the spectral models are:

       1t     - single temperature component, fixed metallicity
       2t     - two temperature components, fixed metallicity
     1t_zvar  - single temperature component, variable metallicity
     2t_zvar  - two temperature components, variable metallicity
  

Reduced_Chi_Squared
The reduced Chi2 of the best-fit spectral model to the X-ray source. As a general criterion to determine the parameters from the best-fit modeling, the authors accepted as a good fit the models with the lowest number of free parameters that realize the probability P(Chi2 > Chi20 ) > 0.01. In the case of two very bright sources, they accepted the best-fit parameters from the 2-T and Z variable model even though P(Chi2 > Chi20 ) < 0.01, because the overall shape of the spectrum was well fit. Only near a few blends of lines was the agreement with the best-fit model poor.

DoF
The number of degrees of freedom of the best-fit spectral model to the X-ray source.

NH
The hydrogen column density NH towards the X-ray source, in atoms cm-2, inferred from the best-fit spectral model to the X-ray source.

NH_Error
The uncertainty in the hydrogen column density NH towards the X-ray source, in atoms cm-2, inferred from the best-fit spectral model.

APEC_kT_1
The temperature, in keV, of the first APEC Component inferred from the best-fit spectral model for the X-ray source.

APEC_kT_1_Error
The uncertainty in the temperature, in keV, of the first APEC Component inferred from the best-fit spectral model for the X-ray source.

APEC_Norm_1
The normalization, in cm-5, of the first APEC Component inferred from the best-fit spectral model for the X-ray source.

APEC_Norm_1_Error
The uncertainty in the normalization, in cm-5, of the first APEC Component inferred from the best-fit spectral model for the X-ray source.

APEC_kT_2
The temperature, in keV, of the second APEC Component (if present) inferred from the best-fit spectral model for the X-ray source.

APEC_kT_2_Error
The uncertainty in the temperature, in keV, of the second APEC Component (if present).

APEC_Norm_2
The normalization, in cm-5, of the second APEC Component (if present) inferred from the best-fit spectral model for the X-ray source.

APEC_Norm_2_Error
The uncertainty in the normalization, in cm-5, of the second APEC Component (if present).

APEC_Abundance
The global metal abundance Z of the best-fit spectral model for the X-ray source.

Flux
The unabsorbed 0.3 - 8.0 keV X-ray flux of the X-ray source, in erg s-1 cm-2, obtained from the best-fit spectral model for the 232 brightest X-ray sources, or from count rate to flux conversion factors (CFs) for the fainter sources. The CFs for faint sources have been calculated by taking the median of the temperatures and absorption obtained from the spectral fits of the bright sources for each IR class. With PIMMS software and by assuming an absorbed 1-T APEC thermal model, the CFs have been calculated for the MOS camera and the filter used, given that the authors derived the rates for MOS with the wavelet detection code. The CF values are: 1.5 x 10-11, 9.74 x 10-12 and 6.71 x 10-12 erg cm-2 counts -1 for Class I, II and III objects, respectively.

IR_Match
This HEASARC-created parameter designates the specific matching IR counterpart in the 2MASS + Spitzer catalog within 5 arcseconds of the X-ray source. If there is no identified IR counterpart, ir_match is set to 0, for the first listed IR counterpart to 1, for the second and third, to 2 and 3, respectively.

RA_IR
The Right Ascension of the infrared counterpart to the X-ray source in the selected equinox. This was given in J2000 decimal degrees and to a precision of 10-4 degrees (0.36 arcseconds) in the original source table.

Dec_IR
The Declination of the infrared counterpart to the X-ray source in the selected equinox. This was given in J2000 decimal degrees and to a precision of 10-4 degrees (0.36 arcseconds) in the original source table.

Jmag
The 2MASS J band magnitude of the infrared counterpart to the X-ray source.

Hmag
The 2MASS H band magnitude of the infrared counterpart to the X-ray source.

Ks_Mag
The 2MASS Ks band magnitude of the infrared counterpart to the X-ray source.

IRAC_3p6_um_Mag
The Spitzer/IRAC 3.6-micron band magnitude of the infrared counterpart to the X-ray source.

IRAC_4p5_um_Mag
The Spitzer/IRAC 4.5-micron band magnitude of the infrared counterpart to the X-ray source.

IRAC_5p8_um_Mag
The Spitzer/IRAC 5.8-micron band magnitude of the infrared counterpart to the X-ray source.

IRAC_8p0_um_Mag
The Spitzer/IRAC 8.0-micron band magnitude of the infrared counterpart to the X-ray source.

MIPS_24_um_Mag
The Spitzer/MIPS 24-micron band magnitude of the infrared counterpart to the X-ray source.

IR_Spectrum_Flag
This Boolean flag parameter is set to 'T' to indicates that the IR counterpart to the X-ray source is a Class 0, I or flat-spectrum object, else is 'F'.

Class_2_Status_Flag
This Boolean flag parameter is set to 'T' to indicates that the IR counterpart to the X-ray source is a Class II candidate object, else is 'F'.

Class_3_Status_Flag
This Boolean flag parameter is set to 'T' to indicates that the IR counterpart to the X-ray source is a Class III candidate object, else is 'F'.

IR_Xray_Offset
The angular separation between the X-ray source and the corresponding IR counterpart positions, in arcseconds.


Contact Person

Questions regarding the L1641IOXMM database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 7-Aug-2013