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17831. X-ray properties of Seyfert 1 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/713/L11
Title:
X-ray properties of Seyfert 1 galaxies
Short Name:
J/ApJ/713/L11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use publicly available XMM-Newton data to systematically compare the hard X-ray photon indices, {Gamma}_2-10keV_, and the iron K{alpha} emission lines of narrow- and broad-line Seyfert 1 (NLS1 and BLS1) galaxies. We compile a flux-limited (f_2-10keV_>=1x10^-12^erg/s/cm^2^) sample including 114 radio-quiet objects, with the 2-10keV luminosity ranging from 10^41^ to 10^45^erg/s. 86 out of these 114 AGNs are included in the CAIXA catalogue (Bianchi et al. 2009, Cat. J/A+A/495/421). The redshift range of the present sample is z<0.37, with only seven objects having z>0.2.
17832. X-ray properties of young stellar objects
ID:
ivo://CDS.VizieR/J/A+A/475/959
Title:
X-ray properties of young stellar objects
Short Name:
J/A+A/475/959
Date:
21 Oct 2021
Publisher:
CDS
Description:
To study the X-ray properties of young stellar objects (YSOs), we analyze an exceptionally sensitive Chandra dataset of the Coronet cluster in the CrA star-forming region, achieving a limiting luminosity of L_X,min_~5x10^26^erg/s for lightly absorbed sources. This dataset represents one of the most sensitive X-ray observations ever obtained of a star-forming region. The X-ray data are used to investigate the membership status of tentative members of the region, to derive plasma temperatures and X-ray luminosities of the YSOs, and to investigate variability on the timescale of several years. 46 of the 92 X-ray sources in the merged Chandra image can be identified with optical or near/mid-infrared counterparts. X-ray emission is detected from all of the previously known optically visible late-type (spectral types G to M) stellar cluster members, from five of the eight brown dwarf candidates, and from nine embedded objects ("protostars") with class 0, class I, or flat-spectrum spectral-energy distributions (SEDs) in the field of view. While the Herbig Ae/Be stars TY CrA and R CrA, a close companion of the B9e star HD 176386, and the F0e star T CrA are detected, no X-ray emission is found from any of the Herbig-Haro (HH) objects or the protostellar cores without infrared source. We find indications for diffuse X-ray emission near R CrA/IRS 7.
17833. X-ray/radio data of high energy peaked BL Lacs
ID:
ivo://CDS.VizieR/J/A+A/434/385
Title:
X-ray/radio data of high energy peaked BL Lacs
Short Name:
J/A+A/434/385
Date:
21 Oct 2021
Publisher:
CDS
Description:
The fully identified complete sample including 150 extreme HBL BL Lacs is presented in Table 1 where we give the source name built with the catalog identification code SHBL (where S stands for "Sedentary" survey and HBL for High energy peaked BL Lacs) and the arcsecond precision optical coordinates of the source taken from the APM and COSMOS on-line services; we give also the RASS name, the X-ray flux (0.1-2.4keV), the radio flux (20cm, from the NVSS survey), and the optical apparent V magnitude (from APM and COSMOS) respectively; we give the redshift when available and the reference for the optical identification. In Table 2 we report properties for five bright elliptical galaxies/low luminosity HBLs in the original sample of high fX/fr sources of Paper I (Giommi et al., 1999MNRAS.310..465G). In Table 3 the 19 rejected emission line AGNs together with their properties are presented.
17834. X-ray & radio fluxes of unassociated 2FGL sources
ID:
ivo://CDS.VizieR/J/ApJ/779/133
Title:
X-ray & radio fluxes of unassociated 2FGL sources
Short Name:
J/ApJ/779/133
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Fermi Gamma-Ray Space Telescope has been detecting a wealth of sources where the multiwavelength counterpart is either inconclusive or missing altogether. We present a combination of factors that can be used to identify multiwavelength counterparts to these Fermi unassociated sources. This approach was used to select and investigate seven bright, high-latitude unassociated sources with radio, UV, X-ray, and {gamma}-ray observations. As a result, four of these sources are candidates to be active galactic nuclei, and one to be a pulsar, while two do not fit easily into these known categories of sources. The latter pair of extraordinary sources might reveal a new category subclass or a new type of {gamma}-ray emitter. These results altogether demonstrate the power of a multiwavelength approach to illuminate the nature of unassociated Fermi sources.
17835. X-ray+Radio sources in XBootes
ID:
ivo://CDS.VizieR/J/MNRAS/396/2011
Title:
X-ray+Radio sources in XBootes
Short Name:
J/MNRAS/396/2011
Date:
21 Oct 2021
Publisher:
CDS
Description:
With the goal of investigating the nature and the environment of the faint radio sources (at mJy level), here are presented results of X-ray identifications of Faint Imaging Radio Survey at Twenty centimetres (FIRST) in the 9deg^2^ Bootes field of the National Optical Astronomy Observatory (NOAO) Deep Wide Field Survey (NDWFS), using data from the Chandra XBootes survey. A total of 92 (10 per cent) FIRST radio sources are identified above the X-ray flux limit f_X_)(0.5-7)keV=8x10^-15^erg/s/cm^2^, and 79 optical counterparts are common to both the radio and X-ray sources. Spectroscopic identifications [obtained from the Sloan Digital Sky Survey (SDSS) survey] were available for 22 sources (27 per cent).
17836. X-rays and protostars in Trifid nebula
ID:
ivo://CDS.VizieR/J/ApJ/562/446
Title:
X-rays and protostars in Trifid nebula
Short Name:
J/ApJ/562/446
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Trifid Nebula is a young HII region, recently rediscovered as a "pre-Orion" star-forming region, containing protostars undergoing violent mass ejections visible in optical jets as seen in images from the Infrared Space Observatory and the Hubble Space Telescope. We report the first X-ray observations of the Trifid Nebula using ROSAT and ASCA. The ROSAT image shows a dozen X-ray sources, with the brightest X-ray source being the O7 star, HD 164492, which provides most of the ionization in the nebula. We also identify 85 T Tauri star and young, massive star candidates from near-infrared colors using the JHKs color-color diagram from the Two-Micron All-Sky Survey (2MASS). Ten X-ray sources have counterpart near-infrared sources. The 2MASS stars and X-ray sources suggest there are potentially numerous protostars in the young HII region of the Trifid. ASCA moderate-resolution spectroscopy of the brightest source shows hard emission up to 10keV with a clearly detected FeK line.
17837. X-Ray Selected BL Lac Objects Catalog
ID:
ivo://nasa.heasarc/xrayselbll
Title:
X-Ray Selected BL Lac Objects Catalog
Short Name:
XRAYSELBLL
Date:
14 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains a catalog of 312 X-ray selected BL Lacertae objects (XBLs), optically identified through the end of 2011. It contains the names from different surveys, equatorial coordinates, redshifts, multi-frequency flux values, and luminosities for each source. In the reference, the different characteristics of these XBLs are statistically investigated (redshift, radio/optical/X-ray luminosities, central black hole (BH) mass, synchrotron peak frequency, broadband spectral indices, optical flux variability). Their values were collected through an extensive bibliographic and database search or calculated by the author. The redshifts range from 0.031 to 0.702 with a maximum of the distribution at z = 0.223. The 1.4-GHz luminosities of XBLs log (nu * L&lt;sub&gt;nu&lt;/sub&gt;) ~ 39 - 42 (in units of erg s&lt;sup&gt;-1&lt;/sup&gt;), while the optical V and X-ray (0.1-2.4 keV) bands show log (nu * L&lt;sub&gt;nu&lt;/sub&gt;) ~ 43 - 46 (same units). The XBL hosts are elliptical galaxies with effective radii r&lt;sub&gt;eff&lt;/sub&gt; = 3.26 - 25.40 kpc and ellipticities e = 0.04 - 0.52. Their R-band absolute magnitudes M&lt;sub&gt;R&lt;/sub&gt; range from -21.11 mag to -24.86 mag with a mean value of -22.83 mag. The V - R indices of the hosts range from 0.61 to 1.52 and reveal a fourth-degree polynomial relationship with z that enabled the author to evaluate the redshifts of five sources whose V - R indices were determined from the observations, but whose redshifts values are either not found or not confirmed. The XBL nuclei show a wider range of 7.31 mag for M&lt;sub&gt;R&lt;/sub&gt;, with the highest luminosity corresponding to M&lt;sub&gt;R&lt;/sub&gt; = -27.24 mag. The masses of the central BHs are found in the interval log M&lt;sub&gt;BH&lt;/sub&gt; = 7.39 - 9.30 (in units of solar masses), with the maximum of the distribution at log M&lt;sub&gt;BH&lt;/sub&gt;/M&lt;sub&gt;sun&lt;/sub&gt; = 8.30. The synchrotron peak frequencies are spread over the range log nu&lt;sub&gt;peak&lt;/sub&gt; = 14.56 - 19.18 Hz, with a peak of the distribution at log nu&lt;sub&gt;peak&lt;/sub&gt; = 16.60 Hz. The broad-band radio-to-optical (alpha&lt;sub&gt;ro&lt;/sub&gt;), optical-to-X-ray (alpha&lt;sub&gt;ox&lt;/sub&gt;), and radio-to-X-ray (alpha&lt;sub&gt;rx&lt;/sub&gt;) spectral indices are distributed in the intervals (0.17, 0.59), (0.56, 1.48), and (0.41, 0.75), respectively. In the optical energy range, the overall flux variability increases, on average, towards shorter wavelengths: Delta(m) = 1.22, 1.50, and 1.82 through the R, V, B bands of the Johnson-Cousins system, respectively. XBLs seem be optically less variable at intranight timescales compared to radio-selected BL Lacs (RBLs). This table was created by the HEASARC in June 2013 based on an electronic version of Table 2 from the reference paper which was obtained form the AJ web site. This is a service provided by NASA HEASARC .
17838. X-ray-selected galaxy clusters BCG offsets
ID:
ivo://CDS.VizieR/J/MNRAS/478/5473
Title:
X-ray-selected galaxy clusters BCG offsets
Short Name:
J/MNRAS/478/5473
Date:
08 Feb 2022 11:49:23
Publisher:
CDS
Description:
We used optical imaging and spectroscopic data to derive substructure estimates for local Universe (z<0.11) galaxy clusters from two different samples. The first was selected through the Sunyaev-Zel'dovich (SZ) effect by the Planck satellite, and the second is an X-ray-selected sample. In agreement to X-ray substructure estimates, we found that the SZ systems have a larger fraction of substructure than the X-ray clusters. We have also found evidence that the higher mass regime of the SZ clusters, compared to the X-ray sample, explains the larger fraction of disturbed objects in the Planck data. Although we detect a redshift evolution in the substructure fraction, it is not sufficient to explain the different results between the higher-z SZ sample and the X-ray one. We have also verified a good agreement (~60 per cent) between the optical and X-ray substructure estimates. However, the best level of agreement is given by the substructure classification given by measures based on the brightest cluster galaxy (BCG), either the BCG-X-ray centroid offset, or the magnitude gap between the first and second BCGs. We advocate the use of those two parameters as the most reliable and cheap way to assess cluster dynamical state. We recommend an offset cut-off ~0.01xR_500_ to separate relaxed and disturbed clusters. Regarding the magnitude gap, the separation can be done at {Delta}m_12_=1.0. The central galaxy paradigm (CGP) may not be valid for ~20 per cent of relaxed massive clusters. This fraction increases to ~60 per cent for disturbed systems.
17839. X-Ray Selected High-z AGN Catalog
ID:
ivo://nasa.heasarc/xshzagncxo
Title:
X-Ray Selected High-z AGN Catalog
Short Name:
XSHZAGNCXO
Date:
14 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the results from an analysis of the largest high-redshift (z &gt; 3) X-ray-selected active galactic nucleus (AGN) sample to date, combining the Chandra Cosmological Evolution Survey and Chandra Multi-wavelength Project surveys and doubling the previous samples. The sample comprises 209 X-ray-detected AGNs, over a wide range of rest-frame 2-10 keV luminosities log L&lt;sub&gt;X&lt;/sub&gt; = 43.3 - 46.0 erg/s. X-ray hardness ratios show that ~39 per cent of the sources are highly obscured, N&lt;sub&gt;H&lt;/sub&gt; &gt; 10&lt;sup&gt;22&lt;/sup&gt; cm&lt;sup&gt;-2&lt;/sup&gt;, in agreement with the ~37 per cent of type-2 AGNs found in this sample based on their optical classification. For ~26 per cent of objects, there are mismatched optical and X-ray classifications. Utilizing the 1/V&lt;sub&gt;max&lt;/sub&gt; method, the authors confirm that the comoving space density of all luminosity ranges of AGNs decreases with redshift above z &gt; 3 and up to z ~ 7. With a significant sample of AGNs (N = 27) at z &gt; 4, it is found that both source number counts in the 0.5-2 keV band and comoving space density are consistent with the expectation of a luminosity-dependent density evolution (LDDE) model at all redshifts, while they exclude the luminosity and density evolution (LADE) model. The measured comoving space density of type-1 and type-2 AGNs shows a constant ratio between the two types at z &gt; 3. These results for both AGN types at these redshifts are consistent with the expectations of LDDE model. The high-redshift AGN sample used in this work has been selected from the C-COSMOS X-ray catalog, combining the spectroscopic and photometric information available from the identification catalogue of X-ray C-COSMOS sources (Civano et al. 2011, ApJ, 741, 91; 2012, ApJS, 201, 30) and the ChaMP (Chandra Multi-wavelength Project) X-ray catalog using only the 323 ChaMP ObsIDs overlapping with Sloan Digital Sky Survey (SDSS; Richards et al. 2006, AJ, 131, 2766) DR5 imaging. This table was created by the HEASARC in March 2016 based on the &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/445/1430"&gt;CDS catalog J/MNRAS/445/1430&lt;/a&gt; file tablea1.dat. This is a service provided by NASA HEASARC .
17840. X-ray-selected normal galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/360/782
Title:
X-ray-selected normal galaxies
Short Name:
J/MNRAS/360/782
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper we estimate the local (z<0.22) X-ray luminosity function of 'normal' galaxies derived from the XMM-Newton Needles in the Haystack Survey. This is an on-going project that aims to identify X-ray-selected normal galaxies (i.e. non-AGN dominated) in the local Universe. We are using a total of 70 XMM-Newton fields covering an area of 11deg^2^ which overlap with the Sloan Digital Sky Survey Data Release 2. Normal galaxies are selected on the basis of their resolved optical light profile, their low X-ray-to-optical flux ratio [log(fx/fo)<-2] and soft X-ray colours. We find a total of 28 candidate normal galaxies to the 0.58keV band flux limit of 2x10^-15^erg/cm2/s. Optical spectra are available for most sources in our sample (82 per cent). These provide additional evidence that our sources are bona fide normal galaxies with X-ray emission coming from diffuse hot gas emission and/or X-ray binaries rather than a supermassive black hole.

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