- ID:
- ivo://nasa.heasarc/chansexagn
- Title:
- Chandra Serendipitous Extragalactic X-Ray Source ID (SEXSI)/Spitzer AGN Catalog
- Short Name:
- CHANSEXAGN
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors compare the relative merits of active galactic nuclei (AGN) selection at X-ray and mid-infrared wavelengths using data from moderately deep fields observed by both Chandra and Spitzer. The X-ray-selected AGN sample and associated photometric and spectroscopic optical follow-up are drawn from a subset of fields studied as part of the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program. Mid-infrared data in these fields are derived from targeted and archival Spitzer imaging, and mid-infrared AGN selection is accomplished primarily through application of the Infrared Array Camera (IRAC) color-color AGN "wedge" selection technique. Nearly all X-ray sources in these fields which exhibit clear spectroscopic signatures of AGN activity have mid-infrared colors consistent with IRAC AGN selection. These are predominantly the most luminous X-ray sources. X-ray sources that lack high-ionization and/or broad lines in their optical spectra are far less likely to be selected as AGNs by mid-infrared color selection techniques. The fraction of X-ray sources identified as AGN in the mid-infrared increases monotonically as the X-ray luminosity increases. Conversely, only 22% of mid-infrared-selected AGN are detected at X-ray energies in the moderately deep (t_exp_n~ 100 ks) SEXSI Chandra data. The authors have expanded the multi-wavelength data available for six SEXSI fields by obtaining Spitzer imaging observations. All six fields have deep Chandra X-ray images, optical imaging, and extensive, deep optical spectroscopy -- all of which has been published in Harrison et al. (2003, ApJ, 596, 944), Eckart et al. (2005, ApJS, 156, 35), and Eckart et al. (2006, ApJS, 165, 19). The authors obtained mid-infrared imaging through both archival and targeted Spitzer programs which include imaging at 3.6, 4.5, 5.8, and 8 micron (µm) from IRAC (PID 00017, 00064, 20694 and 20808), and imaging at 24 um from MIPS (PID 20808 and 00083). This table contains mid-IR photometric data for 290 hard X-ray-selected SEXSI sources. Each of the four IRAC catalogs as well as the MIPS catalog was individually matched to the SEXSI X-ray source positions using a 2.5 arcseconds search radius. To calculate a false match rate, the authors shifted the X-ray source catalog by 1' and matched to the IRAC and MIPS catalogs; this entire procedure was repeated 6 times using different 1' shifts. The resulting false match rates were 10.1% (3.6 um), 7.2% (4.5 um), 3.7% (5.8 um), 2.6% (8.0 um), 1% (24 um), and <1% for four-band-detected IRAC sources. This table was created by the HEASARC in Match 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/708/584">CDS Catalog J/ApJ/708/584</a> file table2.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/mystixires
- Title:
- MassiveYoungStar-FormingComplexStudyinIR&X-Rays:IR-ExcessSources
- Short Name:
- MYSTIXIRES
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Massive Young Star-Forming Complex Study in Infrared and X-rays (MYStIX) project provides a comparative study of 20 Galactic massive star-forming complexes with distances between 0.4 and 3.6 kpc. Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. In this particular study, the authors present the methodology for the second pathway using Spitzer/IRAC, 2MASS, and UKIRT imaging and photometry. Although IRE selection of YSOs is well-trodden territory, MYStIX presents unique challenges. The target complexes range from relatively nearby clouds in uncrowded fields located toward the outer Galaxy (e.g., NGC 2264, the Flame Nebula) to more distant, massive complexes situated along complicated, inner Galaxy sightlines (e.g., NGC 6357, M 17). The authors combine IR spectral energy distribution (SED) fitting with IR color cuts and spatial clustering analysis to identify IRE sources and to isolate probable YSO members in each MYStIX target field from the myriad types of contaminating sources that can resemble YSOs: extragalactic sources, evolved stars, nebular knots, and even unassociated foreground/background YSOs. Applying their methodology consistently across 18 of the target complexes, they produce the MYStIX IRE Source (MIRES) Catalog comprising 20,719 sources, including 8,686 probable stellar members of the MYStIX target complexes. They also classify the SEDs of 9,365 IR counterparts to MYStIX X-ray sources to assist the first pathway, the identification of X-ray-detected stellar members. The MYStIX project, described by Feigelson et al. (2013, ApJS, 209, 26), provides a comprehensive, parallel study of 20 Galactic massive star-forming regions. The basic input data for the MIRES Catalog were near-IR (NIR) and mid-IR (MIR) photometric catalogs. The authors also used NIR and MIR images and mosaics for visualizing the point-source populations with respect to various nebular structures. They provide high-level descriptions of each input catalog in section 2 of the reference paper. This table contains the MYStIX IRE Source (MIRES) Catalog comprising IR data on 20,719 sources, including 8,686 probable stellar members of the MYStIX target complexes, viz., massive star-forming regions (MSFRs), which was given in Table 2 of the reference paper. It does not include the IR data of the above-mentioned 9,365 IR counterparts to MYStIX X-ray sources (the SED Classification of IR Counterparts to MYStIX X-ray sources (SCIM-X Catalog) that were listed in Table 7 of the reference paper. This table was created by the HEASARC in February 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/209/31">CDS Catalog J/ApJS/209/31</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/mystixmidi
- Title:
- MassiveYoungStar-FormingComplexStudyinIR&X-Rays:Mid-IRSourceCatalogs
- Short Name:
- MYSTIXMIDI
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Spitzer IRAC observations and stellar photometric catalogs are presented for the Massive Young star-forming complex Study in the Infrared and X-ray (MYStIX). MYStIX is a multi-wavelength census of young stellar members of 20 nearby (distances < 4 kpc), Galactic, star-forming regions (SFRs) that contain at least one O-type star. All regions have data available from the Spitzer Space Telescope consisting of GLIMPSE or other published catalogs for 11 regions and results of the authors' own photometric analysis of archival data for the remaining 9 regions. The authors also reduced the GLIMPSE data for the W 3 SFR using the aperture photometry method in order to compare the results obtained using the two methods (see Section 3.4.2 of the reference paper). The reference paper seeks to construct deep and reliable catalogs of sources from the Spitzer images. Mid-infrared study of these regions faces challenges of crowding and high nebulosity. These new catalogs typically contain fainter sources than existing Spitzer studies, which improves the match rate to Chandra X-ray sources that are likely to be young stars, but increases the possibility of spurious point-source detections, especially peaks in the nebulosity. IRAC color-color diagrams help distinguish spurious detections of nebular polycyclic aromatic hydrocarbon (PAH) emission from the infrared excess associated with dusty disks around young stars. The distributions of sources on the mid-infrared color-magnitude and color-color diagrams reflect differences between MYStIX regions, including astrophysical effects such as stellar ages and disk evolution. The GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) Survey is a Legacy Science Program of the Spitzer Space Telescope to study star formation in the disk of the Milky Way Galaxy. It contains six MYStIX regions - the Lagoon Nebula, the Trifid Nebula, NGC 6334, the Eagle Nebula, M 17, and NGC 6357 - within the 2-degree wide strip along the Galactic equator (GLIMPSE I and II data releases). Furthermore, Spitzer images and photometry for RCW 38 and NGC 3576 come from the Vela-Carina survey (Majewski et al. 2007, Spitzer Proposal 40791), using a similar observing strategy with mosaicking and photometric analysis as performed with the GLIMPSE pipeline. The authors obtained publicly available raw IRAC images from the Spitzer Heritage Archive for nine MYStIX regions without GLIMPSE coverage. The target list and details of the Astronomical Observation Requests (AORs) are provided in Table 1 of the reference paper. The camera spatial resolutions are FWHM = 1.6" to 1.9" from 3.6 to 8.0um. This table contains the combined IRAC source lists from the GLIMPSE photometry of W 3 and the aperture photometry of the 9 SFRs listed in Table 4, part 1 of the reference paper. This table was created by the HEASARC in February 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/209/29">CDS Catalog J/ApJS/209/29</a> files table2.dat and table3.dat. To distinguish from which table a source originated, the HEASARC has added a parameter called table_number listing the number of the source table, 2 or 3. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rcw38yso
- Title:
- RCW 38 Young Stellar Objects Catalog
- Short Name:
- RCW38YSO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from a study of the structure of the high-mass star-forming region RCW 38 and the spatial distribution of its young stellar population. Spitzer Infrared Array Camera (IRAC) photometry (3-8 micron) is combined with Two Micron All Sky Survey (2MASS) near-IR data to identify young stellar objects (YSOs) by IR-excess emission from their circumstellar material. Chandra X-ray data are used to identify class III pre-main-sequence stars lacking circumstellar material. The authors identify 624 YSOs: 23 class 0/I and 90 flat spectrum (FS) protostars, 437 class II stars, and 74 class III stars. They also identify 29 (27 new) O star candidates over the IRAC field. Seventy-two stars exhibit IR-variability, including 7 class 0/I and 12 flat spectrum YSOs. A further 177 tentative candidates are identified by their location in the IRAC [3.6] versus [3.6]-[5.8] color-magnitude diagram. The authors find strong evidence of subclustering in the region. Three subclusters were identified surrounding the central cluster, with massive and variable stars in each subcluster. The central region shows evidence of distinct spatial distributions of the protostars and pre-main-sequence stars. A previously detected IR cluster, DB2001_Obj36, has been established as a subcluster of RCW 38. This suggests that star formation in RCW 38 occurs over a more extended area than previously thought. The gas-to-dust ratio is examined using the X-ray derived hydrogen column density, NH and the K-band extinction, and found to be consistent with the diffuse interstellar medium, in contrast with Serpens and NGC 1333. The authors posit that the high photoionizing flux of massive stars in RCW 38 affects the agglomeration of the dust grains. This table contains the list of 624 young stellar objects (given in Tables 3 and 4 of the reference paper) found among the Spitzer sources in the field of RCW 38 using the two selection techniques described in Section 3 of the reference paper: (1) selection of stars with IR excesses in IR color-color diagrams, and (2) identification of X-ray luminous YSOs by comparing X-ray sources with IR detections. The latter technique was used to identify Type III YSOs lacking emission from a dusty disk. This table does NOT contain (i) the 177 candidate YSOs listed in Table 5 of the reference paper which were identified using the [3.6] versus [3.6] - [5.8] color-magnitude diagram, since contamination removal methods could not be utilized for these objects, (ii) the 24 candidate variable YSOs listed in Table 6 of the reference paper, nor (iii) 21 of the 29 candidate O-star cluster members which were listed in table 7 of the reference paper. This table was created by the HEASARC in January 2012 based on an electronic version of Tables 3 and 4 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/sporiabyso
- Title:
- Spitzer Survey of Orion A and B Molecular Clouds YSOs Catalog
- Short Name:
- SPORIABYSO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments on board Spitzer. In total, five distinct fields were mapped, covering 9 deg<sup>2</sup> in five mid-IR bands spanning 3 - 24 microns (µm). The survey includes the Orion Nebula Cluster, the Lynds 1641, 1630, and 1622 dark clouds, and the NGC 2023, 2024, 2068, and 2071 nebulae. These data are merged with the Two Micron All Sky Survey point source catalog to generate a catalog of eight-band photometry. The authors identify 3479 dusty young stellar objects (YSOs) in the Orion molecular clouds by searching for point sources with mid-IR colors indicative of reprocessed light from dusty disks or in-falling envelopes. The YSOs are subsequently classified on the basis of their mid-IR colors and their spatial distributions are presented. The authors classify 2991 of the YSOs as pre-main-sequence stars with disks and 488 as likely protostars. Most of the sources were observed with IRAC in two to three epochs over six months; the authors search for variability between the epochs by looking for correlated variability in the 3.6 and 4.5 um bands. They find that 50% of the dusty YSOs show variability. The variations are typically small (~ 0.2 mag) with the protostars showing a higher incidence of variability and larger variations. The observed correlations between the 3.6, 4.5, 5.8, and 8 um variability suggests that we are observing variations in the heating of the inner disk due to changes in the accretion luminosity or rotating accretion hot spots. This table was created by the HEASARC in January 2013 based on an electronic version of Table 4 from the reference paper which was obtained from the AJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/swirecxo
- Title:
- Spitzer Wide-Area IR Extra-Galactic Survey Chandra X-Ray Sources
- Short Name:
- SWIRECXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from deep combined observations with Spitzer and Chandra of the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) in the ELAIS N1 region. This survey was used to investigate the nature of the faint X-ray and IR sources in common, to identify active galactic nucleus (AGN)/starburst diagnostics, and to study the sources of the X-ray and cosmic infrared backgrounds (XRB and CIRB). In the 17' x 17' area of the Chandra ACIS-I image there were approximately 3400 SWIRE near-IR sources with 4-sigma detections in at least two Infrared Array Camera (IRAC) bands and 988 sources detected at 24 micron (µm) with the Multiband Imaging Photometer (MIPS) brighter than a 24-um flux S_24 ~ 0.1 mJy. Of these, 102 IRAC and 59 MIPS sources have Chandra counterparts, out of a total of 122 X-ray sources present in the area with 0.5 - 8 keV flux > 10-15 erg cm<sup>-2</sup> s<sup>-1</sup>. The SWIRE ELAIS N1 field was imaged by the IRAC multiband camera on Spitzer in 2004 January and with MIPS in early 2004 February. The observations were centered at the position (16h 00m, +59d 01'). The X-ray observations were taken as part of the ELAIS Deep X-ray Survey (EDXS) and are described in detail in Manners et al. (2003, MNRAS, 343, 293). For this analysis, the Chandra Advanced CCD Imaging Spectrometer (ACIS) observation of 75 ks centered on (16h 10m 20.11s, +54d 33' 22.3") (J2000.0) in the ELAIS N1 region. The aim point was focused on the ACIS-I chips, which consist of four CCDs arranged in a 2 x 2 array covering an area of 16.9' x 16.9' (286 square arcmin). Bad pixels and columns were removed, and data were filtered to eliminate high background times (due to strong solar flares), leaving 71.5 ks of good data after filtering. Counts-to-photon calibration assumed a standard power-law model spectrum with photon index Gamma = 1.7. Sources were detected to flux levels of 2.3 x 10<sup>-15</sup> erg s<sup>-1</sup> cm<sup>-2</sup> in the 0.5 - 8 keV band, 9.4 x 10<sup>-16</sup> erg s<sup>-1</sup> cm<sup>-2</sup> in the 0.5 - 2 keV band, and 5.2 x 10<sup>-15</sup> erg s<sup>-1</sup> cm<sup>-2</sup> in the 2 - 8 keV band. Sources are detectable to these flux limits over 90% of the nominal survey area. For this analysis, the authors used sources detected in the full band of ACIS-I only, of which there are 122 in the N1 region. Of the 102 sources in common between Chandra and SWIRE, 83 have significant detections in the separate soft X-ray band (0.5 - 2 keV) and 64 are detected in the hard (2 - 8 keV) band. A simple near-neighbor search was performed to cross-correlate the Spitzer and Chandra source catalogs within the Chandra ACIS-I chip image, using a d = 5" search radius (roughly the quadratic sum of the astrometric errors). All together, the authors found reliably associated counterparts for 102 of the 122 Chandra sources (84% in total). The vast majority of these were detected with the IRAC channels 1 and 2 (3.6 and 4.5 um): 100 of the 122 Chandra sources in each case. As many as 59 Chandra objects are reliably associated with MIPS 24 um sources (all of them having IRAC counterparts), and just 1 had a MIPS 70 um counterpart. Of the 102 Spitzer-identified Chandra sources, three turned out to correspond to Galactic stars on the basis of their position on color-magnitude plots and optical morphology and were excluded from the subsequent analysis (and this table). This table was created by the HEASARC in March 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/129/2074">CDS catalog J/AJ/129/2074</a> file table2.dat, This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/swirelhcxo
- Title:
- SWIRE/Chandra Lockman Hole Field X-Ray Source Catalog
- Short Name:
- SWIRELHCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have carried out a moderate-depth (70 ks), contiguous 0.7 square degrees Chandra survey in the Lockman Hole Field of the Spitzer/SWIRE Legacy Survey coincident with a completed, ultra-deep VLA survey with deep optical and near-infrared imaging in-hand. The primary motivation is to distinguish starburst galaxies and active galactic nuclei (AGNs), including the significant, highly obscured (log N<sub>H</sub> > 23 cm<sup>-2</sup>) subset. Chandra has detected 775 X-ray sources to a limiting broadband (0.3 - 8 keV) flux of ~4 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. This table contains the X-ray catalog, fluxes, hardness ratios, and multi-wavelength fluxes. The log N versus log S agrees with those of previous surveys covering similar flux ranges. The Chandra and Spitzer flux limits are well matched: 771 (99%) of the X-ray sources have infrared (IR) or optical counterparts, and 333 have MIPS 24-micron detections. There are four optical-only X-ray sources and four with no visible optical/IR counterpart. The very deep (~2.7 microJansky rms) VLA data yield 251 (> 4 sigma) radio counterparts, 44% of the X-ray sources in the field. The authors confirm that the tendency for lower X-ray flux sources to be harder is primarily due to absorption. As expected, there is no correlation between observed IR and X-ray fluxes. Optically bright, type 1, and red AGNs lie in distinct regions of the IR versus X-ray flux plots, demonstrating the wide range of spectral energy distributions in this sample and providing the potential for classification/source selection. Many optically bright sources, which lie outside the AGN region in the optical versus X-ray plots (f<sub>r</sub>/f<sub>x</sub> > 10), lie inside the region predicted for red AGNs in IR versus X-ray plots, consistent with the presence of an active nucleus. More than 40% of the X-ray sources in the VLA field are radio-loud using the classical definition of R<sub>L</sub>. The majority of these are red and relatively faint in the optical so that the use of R<sub>L</sub> to select those AGNs with the strongest radio emission becomes questionable. Using the 24-micron to radio flux ratio (q<sub>24</sub>) instead results in 13 of the 147 AGNs with sufficient data being classified as radio-loud, in good agreement with the ~10% expected for broad-lined AGNs based on optical surveys. The authors conclude that q<sub>24</sub> is a more reliable indicator of radio-loudness. Use of R<sub>L</sub> should be confined to the optically selected type 1 AGN. This table was created by the HEASARC in December 2009 based on the machine-readable versions of Tables 3, 4 and 7 from the reference paper which was obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .
