- ID:
- ivo://CDS.VizieR/J/ApJS/184/84
- Title:
- X-ray sources in Cyg OB2 region
- Short Name:
- J/ApJS/184/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 1696 X-ray sources detected in the massive star forming region (SFR) Cygnus OB2 and extracted from two archival Chandra observations of the center of the region. A deep source extraction routine, exploiting the low background rates of Chandra observations was employed to maximize the number of sources extracted. Observations at other wavelengths were used to identify low count-rate sources and remove likely spurious sources. Monte Carlo simulations were also used to assess the authenticity of these sources. X-ray spectra were fitted with thermal plasma models to characterize the objects and X-ray light curves were analyzed to determine their variability. We used a Bayesian technique to identify optical or near-IR counterparts for 1501 (89%) of our sources, using deep observations from the INT Photometric H-alpha Survey, the Two Micron All Sky Survey, and the UKIRT Infrared Deep Sky Survey-Galactic plane Survey. 755 (45%) of these objects have six-band r', H-alpha, i', J, H, and K optical and near-IR photometry. From an analysis of the Poisson false-source probabilities for each source we estimate that our X-ray catalogue includes <1% of false sources, and an even lower fraction when only sources with optical or near-IR associations are considered. A Monte Carlo simulation of the Bayesian matching scheme allows this method to be compared to more simplified matching techniques and enables the various sources of error to be quantified. The catalogue of 1696 objects presented here includes X-ray broad band fluxes, model fits, and optical and near-IR photometry in what is one of the largest X-ray catalogue of a single SFR to date. The high number of stellar X-ray sources detected from relatively shallow observations confirms the status and importance of Cygnus OB2 as one of our Galaxy's most massive SFRs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/613/1179
- Title:
- X-ray sources in Galactic Center
- Short Name:
- J/ApJ/613/1179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the X-ray spectra and variability of the sample of X-ray sources with L_X_~10^31^-10^33^ergs/s identified within the inner 9' of the Galaxy by Muno et al. Very few of the sources exhibit intraday or intermonth variations.
- ID:
- ivo://CDS.VizieR/J/AJ/133/220
- Title:
- X-ray sources in galaxy pairs
- Short Name:
- J/AJ/133/220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive study of the local environments of four elliptical+spiral (E+S) galaxy pairs with the main goal of investigating their formation/evolution histories. We obtained new XMM-Newton data for two pairs (RR 143 and RR 242) that complement existing ROSAT data for the other two (RR 210 and RR 216).
- ID:
- ivo://CDS.VizieR/J/ApJS/212/9
- Title:
- X-ray sources in Hickson Compact Groups
- Short Name:
- J/ApJS/212/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Chandra X-ray point source catalogs for 9 Hickson Compact Groups (HCGs, 37 galaxies) at distances of 34-89Mpc. We perform detailed X-ray point source detection and photometry and interpret the point source population by means of simulated hardness ratios. We thus estimate X-ray luminosities (L_X_) for all sources, most of which are too weak for reliable spectral fitting. For all sources, we provide catalogs with counts, count rates, power-law indices ({Gamma}), hardness ratios, and L_X_, in the full (0.5-8.0keV), soft (0.5-2.0keV), and hard (2.0-8.0keV) bands. We use optical emission-line ratios from the literature to re-classify 24 galaxies as star-forming, accreting onto a supermassive black hole (AGNs), transition objects, or low-ionization nuclear emission regions. Two-thirds of our galaxies have nuclear X-ray sources with Swift/UVOT counterparts. Two nuclei have L_X,0.5-8.0keV_>10^42^erg/s, are strong multi-wavelength active galactic nuclei (AGNs), and follow the known {alpha}_OX_-{nu}L_{nu}(nearUV)_ correlation for strong AGNs. Otherwise, most nuclei are X-ray faint, consistent with either a low-luminosity AGN or a nuclear X-ray binary population, and fall in the "non-AGN locus" in {alpha}_OX_-{nu}L_{nu}(nearUV)_ space, which also hosts other normal galaxies. Our results suggest that HCG X-ray nuclei in high specific star formation rate spiral galaxies are likely dominated by star formation, while those with low specific star formation rates in earlier types likely harbor a weak AGN. The AGN fraction in HCG galaxies with M_R_<=-20 and L_X,0.5-8.0keV_>=10^41^erg/s is 0.08_-0.01_^+0.35^, somewhat higher than the ~5% fraction in galaxy clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/122/866
- Title:
- X-ray sources in IC 348 from Chandra
- Short Name:
- J/AJ/122/866
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained a deep (53 ks) X-ray image of the very young stellar cluster IC 348 with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory. In our image with a sensitivity limit of ~1x10^28^ergs/s (more than 10 times deeper than our ROSAT images of IC 348), 215 X-ray sources are detected. While 115 of these sources can be identified with known cluster members, 58 X-ray sources are most likely new, still unidentified cluster members. About 80% of all known cluster members with masses between ~0.15 and 2M_{sun}_ are visible as X-ray sources in our image. We discover X-ray emission at levels of ~10^28^ergs/s from four of 13 known brown dwarfs and from three of 12 brown dwarf candidates in IC 348. We also detect X-ray emission from two deeply embedded objects, presumably class I protostars, south of the cluster center. Description:
21826. X-ray sources in IC 1396N
- ID:
- ivo://CDS.VizieR/J/ApJ/654/316
- Title:
- X-ray sources in IC 1396N
- Short Name:
- J/ApJ/654/316
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IC 1396N cometary globule (CG) within the large nearby HII region IC 1396 has been observed with the ACIS detector on board the Chandra X-Ray Observatory. We detect 117 X-ray sources, of which ~50-60 are likely members of the young open cluster Trumpler 37 dispersed throughout the HII region, and 25 are associated with young stars formed within the globule. Infrared photometry (2MASS and Spitzer) shows that the X-ray population is very young: 3 older Class III stars, 16 classical T Tauri stars, and 6 protostars including a Class 0/I system.
21827. X-ray sources in M104
- ID:
- ivo://CDS.VizieR/J/ApJ/599/1067
- Title:
- X-ray sources in M104
- Short Name:
- J/ApJ/599/1067
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the population of point sources discovered during an 18.5ks Chandra ACIS-S observation of the Sombrero galaxy. We present the luminosity function and the spectra of the six brightest sources, consider correlations with globular clusters (GCs) and with planetary nebulae, and study the galaxy's population of very soft sources. We detected 122 sources. Twenty-two sources are identified as very soft; of these, five appear to be classical luminous supersoft X-ray sources (SSSs), while 17 may belong to the slightly harder class referred to as quasi-soft (QSSs). There is an overdensity of very soft sources within 2kpc of the nucleus, which is itself the brightest X-ray source. Very soft sources are also found in the disk and halo, with one QSS in a globular cluster (GC).
- ID:
- ivo://CDS.VizieR/J/A+AS/128/331
- Title:
- X-ray Sources in Molecular Clouds
- Short Name:
- J/A+AS/128/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Figure 9: Finding charts for the objects where spectra were taken, based on the APM data base. The cross is centered at the X-ray position. 30 arcsec radius error circles are shown and arrows mark the objects with the available spectra. North is up and East to the left in all charts. Figure 10: Deep CCD images of the X-ray source fields with faint optical counterparts. Circles with 30 arcsec radius are centered on the X-ray position. Capital letters identify the brightest object next to them (see Table 3 for remarks on identification). The filter used and the exposure time are shown above each image in brackets.
21829. X-ray sources in NGC 188
- ID:
- ivo://CDS.VizieR/J/A+A/438/291
- Title:
- X-ray sources in NGC 188
- Short Name:
- J/A+A/438/291
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present the analysis results from XMM-Newton observations of the old open stellar cluster NGC 188, which has an age of about 7Gyr and a near solar metallicity. 58 X-ray sources were detected in the field of view of the EPIC MOS and PN cameras, and 46 sources are new X-ray detections. Visible counterparts were found for 20 sources including the variable star WV 28, the W UMa-type binaries V371 Cep and V372 Cep, and the red giant V11. 9 X-ray sources are identified with probable cluster non-members, while 43 X-ray sources are of unknown membership. X-ray emission was detected from 6 stars with high membership probability above a luminosity threshold of 10^30^erg/s.
21830. X-ray sources in NGC 5775
- ID:
- ivo://CDS.VizieR/J/MNRAS/390/59
- Title:
- X-ray sources in NGC 5775
- Short Name:
- J/MNRAS/390/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the edge-on galaxy NGC 5775, utilizing a 58.2ks Chandra ACIS-S observation together with complementary Hubble Space Telescope (HST) ACS, Spitzer IRAC and other multi-wavelength data sets. This edge-on galaxy, with its disc-wide active star formation, is particularly well suited for studying the disc/halo interaction on subgalactic scales. We detect 27 discrete X-ray sources within the D_25_ region of the galaxy, including an ultra-luminous source with a 0.3-7keV luminosity of ~7x10^40^erg/s.
