- ID:
- ivo://nasa.heasarc/sptszspsc
- Title:
- South Pole Telescope Sunyaev-Zeldovich Survey Point Source Catalog (2020)
- Short Name:
- SPTSZSPSC
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table presents the catalog of emissive point-sources detected in the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey, which is a contiguous 2530 deg<sup>2</sup> area surveyed between 2008-2011 in three bands centered at 95, 150, and 220 GHz. The catalog contains 4845 sources measured at a significance of 4.5 sigma or greater in at least one band, corresponding to detections above approximately 9.8, 5.8, and 20.4 mJy in 95, 150, and 220 GHz, respectively. Spectral behavior in the SPT bands is used for source classification into two populations based on the underlying physical mechanisms of compact, emissive sources that are bright at millimeter wavelengths: synchrotron radiation from active galactic nuclei and thermal emission from dust. The latter population includes a component of high-redshift sources often referred to as submillimeter galaxies (SMGs). In the relatively bright flux ranges probed by the survey, these sources are expected to be magnified by strong gravitational lensing. The survey also contains sources consistent with protoclusters, groups of dusty galaxies at high redshift undergoing collapse. The authors cross-match the SPT-SZ catalog with external catalogs at radio, infrared, and X-ray wavelengths and identify available redshift information. The catalog splits into 3980 synchrotron-dominated and 865 dust-dominated sources and determines a list of 506 SMGs. 10 sources are identified as stars. The SPT is a 10-m telescope located at the Amundsen-Scott South Pole station in Antarctica. At 150 GHz (2 mm), the SPT has arcminute angular resolution and a 1 deg<sup>2</sup> diffraction-limited field of view. The SPT was designed for high-sensitivity millimeter/sub-millimeter observations of faint, low-contrast sources, such as CMB anisotropies. The first survey with the SPT, designated as the SPT-SZ survey, was completed in 2011 November and covers a ~2500 deg<sup>2</sup> region of the southern extragalactic sky in three frequency bands, 95, 150, and 220 GHz, corresponding to wavelengths of 3.2, 2.0, and 1.4 mm. The fields were surveyed to depths of approximately 40, 18, and 70 microK arcmin at 95, 150, and 220 GHz, respectively. This study uses data from 19 fields observed by the SPT between 2008 and 2011. The fields are referred to using the J2000 coordinates of their centers, Right Ascension in hours and Declination in degrees. Table 1 in the reference paper lists the positions and effective areas of these fields.The total effective area used for the catalog and analysis in this present work is 2530 deg<sup>2</sup>. The catalog is an extension of two previous works: Vieira et al. (2010, ApJ, 719, 763) and Mocanu et al. (2013, ApJ, 779, 61) and builds on the same analysis pipeline, adding 1759 deg<sup>2</sup> of newly analyzed data, and additional data for two fields which were re-observed in 2010 and 2011. This table was originally created by the HEASARC in January 2014. It was updated to the 2020 version of this catalog in July 2020, based on a machine-readable catalog which was obtained from the <a href="https://lambda.gsfc.nasa.gov/product/spt/spt_everett2020_ps_catalog_info.cfm">LAMBDA</a> website. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/sptszgalcl
- Title:
- South Pole Telescope-Sunyarv-Zeldovich (SPT-SZ) Survey Catalog
- Short Name:
- SPTSZGALCL
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a catalog of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect signature from 2500 deg<sup>2</sup> of South Pole Telescope (SPT) data. This work represents the complete sample of clusters detected at high significance in the 2500 deg<sup>2</sup> SPT-SZ survey, which was completed in 2011. A total of 677 (409) cluster candidates are identified above a signal-to-noise threshold xi of 4.5 (5.0). Ground- and space-based optical and near-infrared (NIR) imaging confirms overdensities of similarly colored galaxies in the direction of 516 (or 76%) of the xi > 4.5 candidates and 387 (or 95%) of the xi > 5 candidates; the measured purity is consistent with expectations from simulations. Of these confirmed clusters, 415 were first identified in SPT data, including 251 new discoveries reported in this work. The authors estimate photometric redshifts for all candidates with identified optical and/or NIR counterparts; they additionally report redshifts derived from spectroscopic observations for 141 of these systems. The mass threshold of the catalog is roughly independent of redshift above z ~ 0.25 leading to a sample of massive clusters that extends to high redshift. The median mass of the sample is M<sub>500c</sub>(rho<sub>crit</sub>) ~ 3.5x10<sup>14</sup> M<sub>sun</sub> h<sub>70</sub><sup>-1</sup>, the median redshift is z<sub>med</sub> = 0.55, and the highest-redshift systems are at z > 1.4. The combination of large redshift extent, clean selection, and high typical mass makes this cluster sample of particular interest for cosmological analyses and studies of cluster formation and evolution. The South Pole Telescope (SPT) is a 10m diameter telescope located at the National Science Foundation Amundsen-Scott South Pole station in Antarctica. From 2008 to 2011 the telescope was used to conduct the SPT-SZ survey, a survey of ~ 2500 deg<sup>2</sup> of the southern sky at 95, 150, and 220 GHz. The survey covers a contiguous region from 20h to 7h in Right Ascension and -65 to -40 degrees in Declination (see, e.g., Figure 1 in Story et al. 2013, ApJ, 779, 86) and was mapped to depths of approximately 40, 18, and 70 microK-arcmin at 95, 150, and 220 GHz, respectively. The authors use optical and in some cases NIR imaging (Blanco Telescope, Magellan/Baade, Magellan/Clay, Swope, MPG/ESO, New Technology Telescope, Spitzer, WISE) to confirm candidates as clusters and to obtain redshifts for confirmed systems (see section 4 of the reference paper for more details). They have also used a variety of facilities to obtain spectroscopic observations of the SPT clusters (including VLT/FORS2 & Gemini/GMOS-S). This HEASARC table contains the total of 677 cluster candidates which were identified above a signal-to-noise threshold of xi = 4.5 in the 2500 deg<sup>2</sup> SPT-SZ survey. This table was created by the HEASARC in March 2015 based on an electronic version of Table 4 from the reference paper which was obtained from the CDS as their catalog J/ApJS/216/27 file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/spass2p3gh
- Title:
- S-PASS (S-Band Polarization All-Sky Survey) 2.3-GHz Source Catalog
- Short Name:
- SPASS2P3GH
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The S-band Polarization All-Sky Survey (S-PASS) has observed the entire southern sky using the 64-meter Parkes radio telescope at 2.3 GHz with an effective bandwidth of 184 MHz. The surveyed sky area covers all Declinations < 0 degrees. To analyze compact sources the survey data have been re-processed to produce a set of 107 Stokes I maps with 10.75-arcminute resolution and the large scale emission contribution filtered out. In this paper, the authors use these Stokes I images to create a total intensity southern-sky extragalactic source catalog at 2.3 GHz. The source catalog contains 23,389 sources and covers a sky area of 16,600 deg<sup>2</sup>, excluding the Galactic plane for latitudes |b| < 10 degrees. Approximately 8% of the catalogued sources are resolved. S-PASS source positions are typically accurate to within 35 arcseconds. At a flux density of 225 mJy, the S-PASS source catalog is more than 95% complete, and ~94% of S-PASS sources brighter than 500 mJy/beam have a counterpart at lower frequencies. The observations were carried out over the period from October 2007 to January 2010 using the Parkes S-band receiver. The S-band receiver is a package with: a system temperature T<sub>sys</sub> = 20K, a beam Full Width at Half Maximum (FWHM) of 8.9 arcminutes, and a circular polarization front-end that is ideal for linear polarization observations with single-dish telescopes. This table was ingested by the HEASARC in August 2017 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/other/PASA/34.13">CDS catalog J/other/PASA/34.13</a> file s-pass.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/sborbitcat
- Title:
- Spectroscopic Binary Orbits Ninth Catalog (Dynamic Version)
- Short Name:
- SpecBinOrbits
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Ninth Catalog of Spectroscopic Binary Orbits (SB9) continues the series of compilations of spectroscopic orbits carried out over the past 35 years by Batten and collaborators, e.g., the 8th SBO Catalog (SB8, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/V/64">CDS Catalog V/64</a>) of Batten, Fletcher and MacCarthy 1989, Publ. DAO, 17, 1. This catalog is regularly updated. This version of SB9 contains orbits for over three thousand binary systems; notice that the numbers of orbits and binary systems included in this version differ from those in the reference publication, as the latter reflected the 2004 May 1 status of the catalog, when it had 2694 orbits for 2386 binary systems. There is an online version of this catalog, maintained by the authors, which is continuously updated, at <a href="http://sb9.astro.ulb.ac.be/">http://sb9.astro.ulb.ac.be/</a>. This table was created by the HEASARC based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/B/sb9">CDS Catalog B/sb9</a>, using the files main.dat, alias.dat, orbits.dat and notes.txt. The CDS updates it regularly, and this HEASARC version is accordingly updated within a week of such updates. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/spicescxo
- Title:
- SPICES Lynx Field Chandra X-Ray Source Catalog
- Short Name:
- SPICESCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the first results on field X-ray sources detected in a deep, 184.7 ks observation with the Advanced CCD Imaging Spectrometer (ACIS-I) on the Chandra X-Ray Observatory. The observations target the Lynx field (J2000.0 RA = 08h 48m and Dec = +44d 54') of SPICES, the Spectroscopic Photometric Infrared-Chosen Extragalactic Survey, which contains three known X-ray-emitting clusters at redshifts of z = 0.57, 1.26, and 1.27. Not including the known clusters, in the 17' x 17' ACIS-I field the authors detect 132 sources in the 0.5 - 2 keV (soft) X-ray band down to a 2.1-sigma limiting flux of ~ 1.7 x 10<sup>-16</sup> erg/cm<sup>2</sup>/s and 11 sources in the 2 - 10 keV (hard) X-ray band down to a 2.1-sigma limiting flux of ~ 1.3 x 10<sup>-15</sup> erg/cm<sup>2</sup>/s. The combined catalog contains a total of 153 X-ray sources, of which 42 are detected only in the soft band and 21 are detected only in the hard band. Confirming previous Chandra results, the authors find that the fainter sources have harder X-ray spectra, providing a consistent solution to the long-standing "spectral paradox". From deep optical and near-infrared follow-up data, 77% of the X-ray sources have optical counterparts to I = 24, and 71% of the X-ray sources have near-infrared counterparts to K<sub>s</sub> = 20. Four of the 24 sources in the near-IR field are associated with extremely red objects (EROs; I - K<sub>s</sub> >= 4). The authors have obtained spectroscopic redshifts with the Keck telescopes of 18 of the Lynx Chandra sources. These sources comprise a mix of broad-lined active galaxies, apparently normal galaxies, and two late-type Galactic dwarfs. Intriguingly, one Galactic source (number 72) is identified with an M7 dwarf exhibiting non-transient, hard X-ray emission. Thirteen of the Chandra sources are located within regions for which the authors have Hubble Space Telescope imaging. Nine of the sources are detected, showing a range of morphologies: several show compact cores embedded within diffuse emission, while others are spatially extended showing typical galaxy morphologies. Two of the Chandra sources in this subsample appear to be associated with mergers. ACIS-I observations of the Lynx field were obtained on 2000 May 3 (65 ks; OBS-ID 1708) and 2000 May 4 (125 ks; OBS-ID 927). Time intervals with background rates larger than 3 sigma over the quiescent value of ~ 0.30 counts s<sup>-1</sup> per chip in the 0.3 - 10 keV band were removed. This procedure gave 60.7 ks of effective exposure out of the first observation and 124 ks out of the second, for a total of 184.7 ks. The two observations are almost coincident on the sky, so that the total coverage is 298 arcmin<sup>2</sup>. The aim point for the observations was RA = 08h 48m 54.79s, Dec = +44d 54' 32.9" (J2000.0), and both exposures were obtained in the faint mode when ACIS was at a temperature of -120 C. The Galactic absorbing column for this field is N<sub>H</sub> = 2 x 10<sup>20</sup> cm<sup>-2</sup>. The position angle of the observations was 258.45 degrees. Cosmology-dependent parameters are calculated for two models: an Einstein-de Sitter (EdS) universe consistent with previous work in this field (H<sub>0</sub> = 50 h<sub>50</sub> km s<sup>-1</sup> Mpc<sup>-1</sup>, Omega<sub>M</sub> = 1, and Omega<sub>Lambda</sub> = 0) and the dark energy cosmology (DEC) universe favored by recent work on high-redshift supernovae and fluctuations in the cosmic microwave background (H<sub>0</sub> = 65 km s<sup>-1</sup> Mpc<sup>-1</sup>, Omega<sub>M</sub> = 0.35, and Omega<sub>Lambda</sub> = 0.65). This table was created by the HEASARC in April 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/123/2223">CDS catalog J/AJ/123/2223</a> files table1.dat, table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/spitzmastr
- Title:
- Spitzer Space Telescope Observation Log
- Short Name:
- Spitzer
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains the Spitzer Space Telescope (SST) log of executed and scheduled observations, and is updated on a weekly basis. Spitzer is the fourth and final element in NASA's family of Great Observatories and represents an important scientific and technical bridge to NASA's Astronomical Search for Origins program. The SST Observatory carries an 85-cm cryogenic telescope and 3 cryogenically cooled science instruments capable of performing imaging and spectroscopy in the 3.6 to 160 micron (µm) range. Spitzer was launched on a Delta 7920H from Cape Canaveral into an Earth-trailing heliocentric orbit in August 2003. While the Spitzer cryogenic lifetime requirements are 2.5 years, current estimates indicate that achieving a goal of a 5-year cryogenic mission is possible. For more overview information, refer to the Spitzer Science Center (SSC) Overview at <a href="http://ssc.spitzer.caltech.edu/spitzermission/">http://ssc.spitzer.caltech.edu/spitzermission/</a>. The purpose of this HEASARC table is to help users, particularly those in the high-energy astronomy community, learn about which targets Spitzer has observed or will shortly observe. This table does not at this time have links from table entries to Spitzer data products. Once a particular Spitzer dataset of interest is identified, the SSC Archives/Analysis web page at <a href="http://ssc.spitzer.caltech.edu/archanaly/">http://ssc.spitzer.caltech.edu/archanaly/</a> should be used to access the dataset. The information in this table has been derived from the following files obtained from the SSC website: <p> The schedule of Spitzer science observations as executed: <pre> <a href="http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_obslog.txt">http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_obslog.txt</a> </pre> The list of all approved Spitzer science programs: <pre> <a href="http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_programs.txt">http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/spitzer/spitzer_programs.txt</a> </pre> Notice that this table contains primarily observations (identified by their AOR key value) from the first URL above. A given observation should appear only once in this HEASARC table. The HEASARC checks these URLs for modifications periodically and updates the table whenever changes are detected. 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/ssa22cxo
- Title:
- SSA22 Field Chandra X-Ray Point Source Catalog
- Short Name:
- SSA22CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the main X-ray point-source catalog for a deep ~400-ks Chandra ACIS-I (Advanced CCD Imaging Spectrometer) exposure of the SSA22 field. The observations were centred on a z = 3.09 protocluster, which is populated by Lyman break galaxies (LBGs), Lyman-alpha emitters (LAEs) and extended Lyman-alpha-emitting blobs (LABs). The survey reached ultimate (3 count) sensitivity limits of ~5.7 x 10<sup>-17</sup> and ~3.0 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> for the 0.5-2 and 2-8 keV bands, respectively (corresponding to L(2-10 keV) ~ 5.7 x 10<sup>42</sup> erg s<sup>-1</sup> and L(10-30 keV) ~ 2.0 x 10<sup>43</sup> erg s<sup>-1</sup> at z = 3.09, respectively, for an assumed photon index of Gamma = 1.4). These limits make SSA22 the fourth deepest extragalactic Chandra survey yet conducted, and the only one focused on a known high-redshift structure. In total, the authors detect 297 X-ray point sources and identify one obvious bright extended X-ray source (not included in the current table) over a ~330 arcmin<sup>2</sup> region. In addition to the X-ray data, the authors provide all available optical spectroscopic redshifts and near-infrared and mid-infrared photometry available for their sources. The basic X-ray and infrared properties of their Chandra sources indicate a variety of source types, although absorbed active galactic nuclei (AGN) appear to dominate. In total, they have identified 12 X-ray sources (either via optical spectroscopic redshifts or LAE selection) at z = 3.06 - 3.12 that are likely to be associated with the SSA22 protocluster. These sources have X-ray and multiwavelength properties that suggest they are powered by AGN with 0.5 - 8 keV luminosities in the range of ~ 10<sup>43</sup> - 10<sup>45</sup> erg s<sup>-1</sup>. The authors have analysed the AGN fraction of sources in the protocluster as a function of local LAE source density and find suggestive evidence for a correlation between AGN fraction and local LAE source density (at the ~96 per cent confidence level), implying that supermassive black hole growth at z ~3 is strongest in the highest density regions. This table was created by the HEASARC in February 2010 based on the electronic version of Table 2 from the reference paper which was obtained from the Monthly Notices web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/s254258cxo
- Title:
- S254-S258 Star-Forming Region Chandra X-Ray Point Source Catalog
- Short Name:
- S254258CXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The aim of this study was to find an explanation for the remarkable morphology of the central part of the S254-S258 star forming complex. The authors performed a deep Chandra X-ray observation of the S254-S258 region in order to efficiently discriminate young stars (with and without circumstellar matter) from the numerous older field stars in the area. They detected 364 X-ray point sources in a 17' x 17' (~ 8 x 8 pc) field. This X-ray catalog provides, for the first time, a complete sample of all young stars in the region down to about 0.5 M_{sun}_. A clustering analysis identifies three significant clusters: the central embedded cluster S255-IR and two smaller clusterings in S256 and S258. Sixty-four X-ray sources can be classified as members in one of these clusters. After accounting for X-ray background contaminants, this implies that about 250 X-ray sources constitute a widely scattered population of young stars, distributed over the full field-of-view of the X-ray image. This distributed young stellar population is considerably larger than the previously known number of non-clustered young stars selected by infrared excesses. Comparison of the X-ray luminosity function with that of the Orion Nebula Cluster suggests a total population of ~ 2000 young stars in the observed part of the S254-S258 region. The S254-S258 complex was observed (PI: Preibisch) in November 2009 with the Imaging Array of the Chandra Advanced CCD Imaging Spectrometer (ACIS-I). ACIS-I provides a field of view of 17' x 17' on the sky. At the 1.6 kpc distance of S254-S258 this corresponds to 7.9 x 7.9 pc. The aimpoint of the observation was RA(J2000) = 06h12m54.0s, Dec(J2000) = +17d 59' 24". The observation was performed in the standard 'Timed Event, Faint' mode (with 3 x 3 pixel event islands). The total net exposure time of 74725 s (20.76 h) was split into two parts, separated by about 4 days. The details of these two observation parts are given in Table 1 of the reference paper. The authors first employed the wavdetect algorithm (Freeman et al. 2002, ApJS, 138, 185, a CIAO mexican-hat wavelet source detection tool) for locating X-ray sources in the merged image, and used a rather low detection threshold of 10<sup>-5</sup>. This step was performed in three different energy bands, the total band (0.5 - 8.0 keV), the soft band (0.5 - 2.0 keV), and the hard band (2.0 - 8.0) keV, and with wavelet scales between 1 and 16 pixels. They also performed a visual inspection of the images and added some 30 additional candidates to the merged catalog from the wavelet analysis, resulting in a final catalog of 511 potential X-ray sources. To clean this catalog from spurious sources, they then performed a detailed analysis of each individual candidate source with the ACIS Extract (AE hereafter) software package (Broos et al. 2010, ApJ, 714, 1582). The Poisson probability (P<sub>B</sub>) associated with the "null hypothesis", i.e. that no source exists and the extracted events are solely due to Poisson fluctuations in the local background, was computed for each source using AE. All candidate sources with P<sub>B</sub> > 0.01 were rejected as background fluctuations. After 8 iterations of this pruning procedure the final catalog consisted of 364 sources. It contains 344 primary sources with P<sub>B</sub> < 0.003, and 20 tentative sources with 0.003 < P<sub>B</sub> < 0.01. To obtain an estimate of the intrinsic, i.e. extinction-corrected, X-ray luminosity for sources that are too weak for a detailed spectral analysis, the authors used the XPHOT software, developed by Getman et al. (2010, ApJ, 708, 1760). XPHOT is based on a non-parametric method for the calculation of fluxes and absorbing X-ray column densities of weak X-ray sources. X-ray extinction and intrinsic flux are estimated from the comparison of the apparent median energy of the source photons and apparent source flux with those of high signal-to-noise spectra that were simulated using spectral models characteristic of much brighter sources of similar class previously studied in detail. This method requires at least 4 net counts per source (in order to determine a meaningful value for the median energy) and can thus be applied to 255 of the 364 sources in this table. To calculate luminosities, a distance of 1.6 kpc was assumed. The resulting intrinsic X-ray lumonosities range from 10<sup>29.4</sup> to 10<sup>32.3</sup> erg s<sup>-1</sup>. This table was created by the HEASARC in October 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/533/A121">CDS Catalog J/A+A/533/A121</a> files table2.dat, table3.dat and table5.dat. This is a service provided by NASA HEASARC .
