- ID:
- ivo://CDS.VizieR/J/ApJ/613/279
- Title:
- ACS Virgo Cluster Survey. III. M87
- Short Name:
- J/ApJ/613/279
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ACIS instrument on board the Chandra X-Ray Observatory has been used to carry out the first systematic study of low-mass X-ray binaries (LMXBs) in M87, the giant elliptical galaxy near the dynamical center of the Virgo Cluster. These images - with a total exposure time of 154 ks - are the deepest X-ray observations yet obtained of M87. We identify 174 X-ray point sources, of which 150 are likely LMXBs.
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- ID:
- ivo://CDS.VizieR/J/ApJ/611/821
- Title:
- A2125 in X-ray
- Short Name:
- J/ApJ/611/821
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an 82ks Chandra ACIS-I observation of a large-scale hierarchical complex, which consists of various clusters/groups of galaxies and low surface brightness X-ray emission at z=0.247. This high-resolution Chandra observation allows us for the first time to separate unambiguously the X-ray contributions from discrete sources and large-scale diffuse hot gas. We detect 99 X-ray sources in a 17{arcmin}x17{arcmin} field.
- ID:
- ivo://CDS.VizieR/J/other/Sci/292.2290
- Title:
- Chandra compact binaries in 47 Tuc
- Short Name:
- J/other/Sci/292.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained high-resolution (<~1") deep X-ray images of the globular cluster 47 Tucanae (NGC 104) with the Chandra X-ray Observatory to study the population of compact binaries in the high stellar density core. A 70-kilosecond exposure of the cluster reveals a centrally concentrated population of faint (L_X_~10^30-33^ergs/s) X-ray sources, with at least 108 located within the central 2'x2.5' and >~half with L_X_<~10^30.5^ergs/s. All 15 millisecond pulsars (MSPs) recently located precisely by radio observations are identified, though 2 are unresolved by Chandra. The X-ray spectral and temporal characteristics, as well as initial optical identifications with the Hubble Space Telescope, suggest that >~50 percent are MSPs, about 30 percent are accreting white dwarfs, about 15 percent are main-sequence binaries in flare outbursts, and only two to three are quiescent low-mass X-ray binaries containing neutron stars, the conventional progenitors of MSPs. An upper limit of about 470 times the mass of the sun is derived for the mass of an accreting central black hole in the cluster. These observations provide the first X-ray ``color-magnitude'' diagram for a globular cluster and census of its compact object and binary population. Observations were made on UT 16.31 - 17.22 March, 2000.
- ID:
- ivo://CDS.VizieR/J/ApJS/184/158
- Title:
- Chandra COSMOS survey I.
- Short Name:
- J/ApJS/184/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8Ms, Chandra program that has imaged the central 0.5deg^2^ of the COSMOS field (centered at 10h, +02d) with an effective exposure of ~160ks, and an outer 0.4deg^2^ area with an effective exposure of ~80ks. The limiting source detection depths are 1.9x10^-16^erg/cm2/s in the soft (0.5-2keV) band, 7.3x10^-16^erg/cm2/s in the hard (2-10keV) band, and 5.7x10^-16^erg/cm2/s in the full (0.5-10keV) band. Here we describe the strategy, design, and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of <2x10^-5^ (1655 in the full, 1340 in the soft, and 1017 in the hard bands). By using a grid of 36 heavily (~50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (+/-12%) exposure across the inner 0.5deg^2^ field was obtained, leading to a sharply defined lower flux limit. The widely different point-spread functions obtained in each exposure at each point in the field required a novel source detection method, because of the overlapping tiling strategy, which is described in a companion paper. This method produced reliable sources down to a 7-12 counts, as verified by the resulting logN-logS curve, with subarcsecond positions, enabling optical and infrared identifications of virtually all sources, as reported in a second companion paper.
- ID:
- ivo://CDS.VizieR/J/AJ/122/2810
- Title:
- Chandra Deep Field North Survey. V.
- Short Name:
- J/AJ/122/2810
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extremely deep X-ray survey (~1Ms) of the Hubble Deep Field North (HDF-N) and its environs (~450arcmin^2^) has been performed with the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. This is one of the two deepest X-ray surveys ever performed; for point sources near the aim point, it reaches 0.5-2.0 and 2-8keV flux limits of ~3x10^-17^ and ~2x10^-16^ergs/cm^2^/s, respectively. Here we provide source catalogs, along with details of the observations, data reduction, and technical analysis. Observing conditions, such as background, were excellent for almost all of the exposure. We have detected 370 distinct point sources: 360 in the 0.5-8.0keV band, 325 in the 0.5-2.0keV band, 265 in the 2-8keV band, and 145 in the 4-8keV band. Two new Chandra sources in the HDF-N itself are reported and discussed. Source positions are accurate to within 0.6"-1.7" (at ~90% confidence), depending mainly on the off-axis angle. We also detect two highly significant extended X-ray sources and several other likely extended X-ray sources. We present basic number count results for sources located near the center of the field. Source densities of 7100^+1100^_-940_deg^-2^ (at 4.2x10^-17^ergs/cm^2^/s) and 4200^+670^_580_deg^-2^ (at 3.8x10^-16^ergs/cm^2^/s) are observed in the soft and hard bands, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/578/114
- Title:
- Chandra HRC source in M31
- Short Name:
- J/ApJ/578/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a 47ks observation of the Andromeda galaxy, M31, using the High Resolution Camera of the Chandra X-Ray Observatory. We detect 142 point sources spanning 3 orders of magnitude in luminosity, from L_X_=2x10^35^ to 2x10^38^erg/s in the 0.1-10keV band. The X-ray source location accuracy is better than 1" in the central regions of the galaxy. One source lies within 1.3" of SN 1885 but does not coincide with the UV absorption feature identified as the supernova remnant.
- ID:
- ivo://CDS.VizieR/J/A+A/418/509
- Title:
- Chandra observation of M67
- Short Name:
- J/A+A/418/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 47-ks Chandra/ACIS observation of the old open cluster M67. We detected 25 proper-motion cluster members (including ten new sources) and 12 sources (all new) that we suspect to be members from their locations close to the main sequence (1<B-V<1.7). Of the detected members, 23 are binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/549/441
- Title:
- Chandra observations of Orion Trapezium
- Short Name:
- J/ApJ/549/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory to perform two observations, separated by 3 weeks, of the Orion Trapezium region. The zeroth-order images on the Advanced CCD Imaging Spectrometer provide spatial resolution of 0.5" and moderate energy resolution. Within a 160"x140" region around the Orion Trapezium, we resolve 111 X-ray sources with luminosities between 7x10^28^ and 2x10^32^ergs/s. We do not detect any diffuse emission. All but six sources are identified.
- ID:
- ivo://CDS.VizieR/J/ApJ/566/974
- Title:
- CHANDRA obs. of YSOs in OMC-2 and OMC-3
- Short Name:
- J/ApJ/566/974
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report X-ray results of the Chandra observation of OMC-2 and OMC-3. A deep exposure of ~100ks detects ~400 X-ray sources in the field of view of the ACIS array, providing one of the largest X-ray catalogs in a star-forming region. Coherent studies of the source detection, time variability, and energy spectra are performed. We classify the X-ray sources into Class I, Class II, and Class III+MS based on the J-, H-, and K-band colors of their near-infrared counterparts and discuss the X-ray properties (temperature, absorption, and time variability) along these evolutionary phases.
- ID:
- ivo://CDS.VizieR/J/ApJS/144/213
- Title:
- Chandra X-ray observations of M81
- Short Name:
- J/ApJS/144/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A Chandra X-Ray Observatory ACIS-S imaging observation is used to study the population of X-ray sources in the nearby Sab galaxy M81 (NGC 3031). A total of 177 sources are detected with 124 located within the D_25_ isophote to a limiting X-ray luminosity of ~3x10^36^erg/s. Source positions, count rates, luminosities in the 0.3-8.0 keV band, limiting optical magnitudes, and potential counterpart identifications are tabulated. Spectral and timing analysis of the 36 brightest sources are reported including the low-luminosity active galactic nucleus, SN 1993J, and the Einstein-discovered ultraluminous X-ray source X6.
- ID:
- ivo://CDS.VizieR/J/ApJ/582/382
- Title:
- Chandra X-ray sources in Orion Nebula Cluster
- Short Name:
- J/ApJ/582/382
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this first of two companion papers on the Orion Nebula Cluster (ONC), we present our analysis of a 63ks Chandra HRC-I observation that yielded 742 X-ray detections within the 30'x30' field of view. To facilitate our interpretation of the X-ray image, here we collect a multiwavelength catalog of nearly 2900 known objects in the region by combining 17 different catalogs from the recent literature. We define two reference groups: an infrared sample, containing all objects detected in the K band, and an optical sample comprising low-extinction, well-characterized ONC members. We show for both samples that field object contamination is generally low. Our X-ray sources are primarily low-mass ONC members. The detection rate for optical sample stars increases monotonically with stellar mass from zero at the brown dwarf limit to ~100% for the most massive stars but shows a pronounced dip between 2 and 10M_{sun}_. We determine L_X_ and L_X_/L_bol_ or all stars in our optical sample and utilize this information in our companion paper to study correlations between X-ray activity and other stellar parameters.
- ID:
- ivo://CDS.VizieR/J/ApJ/591/138
- Title:
- Chandra X-ray sources of NGC 1068
- Short Name:
- J/ApJ/591/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the compact X-ray source population in the Seyfert 2 galaxy NGC 1068, imaged with a 50ks Chandra observation. We find a total of 84 compact sources on the S3 chip, of which 66 are located within the 25.0B-mag/arcsec^2^ isophote of the galactic disk of NGC 1068. Spectra have been obtained for the 21 sources with at least 50 counts and modeled with both multicolor disk blackbody and power-law models.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1501
- Title:
- CLASXS: X-ray catalog
- Short Name:
- J/AJ/128/1501
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the X-ray catalog and basic results from our Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest (LHNW) field. Our nine ACIS-I fields cover a contiguous solid angle of 0.4{deg}^2^ and reach fluxes of 5x10^-16^ergs/cm^2^/s (0.4-2keV) and 3x10^-15^ergs/cm^2^/s (2-8keV). Our survey bridges the gap between ultradeep pencil-beam surveys, such as the Chandra Deep Fields (CDFs), and shallower, large-area surveys, allowing a better probe of the X-ray sources that contribute most of the 2-10keV cosmic X-ray background (CXB). We find a total of 525 X-ray point sources and four extended sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/343/293
- Title:
- ELAIS deep X-ray survey. I.
- Short Name:
- J/MNRAS/343/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of two deep (75ks) Chandra observations of the European Large Area Infrared Space Observatory (ISO) Survey (ELAIS) fields N1 and N2 as the first results from the ELAIS deep X-ray survey. This survey is being conducted in well-studied regions with extensive multiwavelength coverage. Here we present the Chandra source catalogues along with an analysis of source counts, hardness ratios and optical classifications. A total of 233 X-ray point sources are detected in addition to two soft extended sources, which are found to be associated with galaxy clusters. An overdensity of sources is found in N1 with 30 per cent more sources than N2, which we attribute to large-scale structure. A similar variance is seen between other deep Chandra surveys. The source count statistics reveal an increasing fraction of hard sources at fainter fluxes. The number of galaxy-like counterparts also increases dramatically towards fainter fluxes, consistent with the emergence of a large population of obscured sources.
- ID:
- ivo://mast.stsci/siap/goods.hst
- Title:
- Great Observatories Origins Deep Survey (GOODS)
- Short Name:
- HST.GOODS
- Date:
- 23 Jul 2020 19:32:07
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- GOODS aims to unite extremely deep observations from NASA's Great Observatories, the Spitzer Space Telescope, Hubble, and Chandra, ESA's XMM-Newton, and from the most powerful ground-based facilities, to survey the distant universe to the faintest flux limits across the broadest range of wavelengths. GOODS will survey a total of roughly 320 square arcminutes in two fields centered on the Hubble Deep Field North and the Chandra Deep Field South.
- ID:
- ivo://CDS.VizieR/J/AJ/127/213
- Title:
- LALA Bootes field X-ray source catalog
- Short Name:
- J/AJ/127/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of a deep, 172ks Chandra observation of the Large Area Lyman Alpha survey (LALA) Bootes field, obtained with the Advanced CCD Imaging Spectrometer (ACIS-I) on board the Chandra X-Ray Observatory. This is one of the deepest Chandra images of the extragalactic sky; only the 2Ms Chandra Deep Field North (CDF-N) and 1Ms Chandra Deep Field South (CDF-S) are substantially deeper. In this paper we present the X-ray source catalog obtained from this image, along with an analysis of source counts and optical identifications. The X-ray image is composed of two individual observations obtained in 2002 and reaches 0.5-2.0 and 2.0-10.0keV flux limits of 1.5x10^-16^ and 1.0x10^-15^ergs/cm^2^/s, respectively, for point sources near the aim point. A total of 168 X-ray sources were detected: 160 in the 0.5-7.0keV band, 132 in the 0.5-2.0keV band, and 111 in the 2.0-7.0keV band. Our primary optical data are R-band imaging from the NOAO Deep Wide-Field Survey (NDWFS), with a limiting magnitude of R=25.7 (Vega, 3{sigma}, and 4" diameter aperture).
17. SEXSI catalog
- ID:
- ivo://CDS.VizieR/J/ApJ/596/944
- Title:
- SEXSI catalog
- Short Name:
- J/ApJ/596/944
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) program is designed to extend greatly the sample of identified extragalactic hard X-ray (2-10keV) sources at intermediate fluxes (~10^-13^ to 10^-15^erg/cm^2^/s). SEXSI, which studies sources selected from more than 2deg^2^, provides an essential complement to the Chandra Deep Fields, which reach depths of 5x10^-16^erg/cm^2^/s (2-10keV) but over a total area of less than 0.2deg^2^. In this paper we describe the characteristics of the survey and our X-ray data analysis methodology. We present the cumulative flux distribution for the X-ray sample of 1034 hard sources and discuss the distribution of spectral hardness ratios. Our logN-logS in this intermediate flux range connects to those found in the Deep Fields, and by combining the data sets, we constrain the hard X-ray population over the flux range in which the differential number counts change slope and from which the bulk of the 2-10keV X-ray background arises. We further investigate the logN-logS distribution separately for soft and hard sources in our sample, finding that while a clear change in slope is seen for the softer sample, the hardest sources are well described by a single power law down to the faintest fluxes, consistent with the notion that they lie at lower average redshift.
- ID:
- ivo://CDS.VizieR/J/AJ/123/2223
- Title:
- SPICES II: CHANDRA observations of Lynx
- Short Name:
- J/AJ/123/2223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our first results on field X-ray sources detected in a deep, 184.7ks observation with the Advanced CCD Imaging Spectrometer (ACIS-I) on the Chandra X-Ray Observatory. The observations target the Lynx field (RA=08h48min, DE=+44{deg}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'x17' ACIS-I field we detect 132 sources in the 0.5-2keV (soft) X-ray band down to a limiting flux of ~1.7x10^-16^ergs/cm^2^/s and 11 sources in the 2-10keV (hard) X-ray band down to a limiting flux of ~1.3x10^-15^ergs/cm^2^/s. The combined catalog contains a total of 153 sources, of which 42 are detected only in the soft band and 21 are detected only in the hard band. Confirming previous Chandra results, we 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 Ks=20. Four of the 24 sources in the near-IR field are associated with extremely red objects (EROs; I-Ks>=4). We 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 is identified with an M7 dwarf exhibiting nontransient, hard X-ray emission. Thirteen of the Chandra sources are located within regions for which we 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. We briefly review non-active galactic nucleus mechanisms to produce X-ray emission and discuss properties of the Lynx Chandra sample in relation to other samples of X-ray and non-X-ray sources.
- ID:
- ivo://CDS.VizieR/B/chandra
- Title:
- The Chandra Archive Log
- Short Name:
- B/chandra
- Date:
- 07 Mar 2022 06:17:49
- Publisher:
- CDS
- Description:
- The Chandra X-Ray Observatory (CXO) is a high-resolution (< 0.5 arcsecond) X-ray telescope with a suite of advanced imaging and spectroscopic instruments. The Observatory was successfully launched by NASA's Space Shuttle Columbia on July 23, 1999. Chandra was designed to provide order-of-magnitude advances over previous X-ray astronomy missions with regards to spatial and spectral resolution. The High Resolution Mirror Assembly (HRMA) produces images with a half-power diameter (HPD) of the point spread function (PSF) of < 0.5 arcsec. Chandra has two focal plane science instruments, i) The Advanced CCD Imaging Spectrometer (ACIS), and ii) The High Resolution Camera (HRC). ACIS is comprised of two CCD arrays, a 4-chip array, ACIS-I ; and a 6-chip array, ACIS-S . ACIS-I was designed for CCD imaging and spectrometry; ACIS-S can be used both for CCD imaging spectrometry and also for high-resolution spectroscopy in conjunction with the HETG grating. A mix of ACIS-S and ACIS-I chips (up to six) may be used for imaging observations. The HRC is comprised of two microchannel plate (MCP ) imaging detectors: the HRC-I designed for wide-field imaging; and, HRC-S designed to serve as a readout for the LETG . The grating systems consist of the Low Energy Transmission Grating (LETG) and the High Energy Transmission Grating (HETG). The HETG , when operated with the HRMA and the ACIS-S , forms the High-Energy Transmission Grating Spectrometer (HETGS ) for high resolution spectroscopy . The HETGS achieves resolving power up to 1000 in the band between 0.4 keV and 10.0 keV. The LETG when operated with the HRC-S , forms the Low Energy Transmission Grating Spectrometer (LETGS ). The LETGS provides the highest spectral resolution on Chandra at low (0.08 - 0.2 keV) energies. This catalogue is a copy of the Chandra Observation Catalog from the Chandra Data Archive (CDA) which is part of the Chandra X-Ray Observatory Science Center (CXC) which is operated for NASA by the Smithsonian Astrophysical Observatory.
- ID:
- ivo://CDS.VizieR/J/AJ/126/539
- Title:
- The Chandra Deep Fields North and South
- Short Name:
- J/AJ/126/539
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present point-source catalogs for the ~2Ms exposure of the Chandra Deep Field North, currently the deepest X-ray observation of the universe in the 0.5-8.0keV band. Five hundred and three (503) X-ray sources are detected over an ~448arcmin^2^ area in up to seven X-ray bands. Twenty (20) of these X-ray sources lie in the central 5.3 arcmin^2^ Hubble Deep Field North (13600^+3800^_-3000_sources/deg^2^). The on-axis sensitivity limits are 2.5x10^-17^ergs/cm^2^/s (0.5-2.0keV) and 1.4x10^-16^ergs/cm^2^/s (2-8keV). Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ~0.3". To allow consistent comparisons, the point-source catalogs for the 1Ms Chandra Deep Field South (CDF-S; see Cat. J/ApJS/139/369) have also been produced. Three hundred and twenty-six (326) X-ray sources are included in the main Chandra South catalog, and an additional 42 optically bright X-ray sources are included in a lower significance Chandra catalog. We find good agreement with the photometry of the previously published CDF-S catalogs; however, we provide significantly improved positional accuracy.