- 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.
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- 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/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.
