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4701. WWFI g'-band obs. of bright galaxy clusters
ID:
ivo://CDS.VizieR/J/ApJS/252/27
Title:
WWFI g'-band obs. of bright galaxy clusters
Short Name:
J/ApJS/252/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore several ways to dissect brightest cluster galaxies (BCGs) and their surrounding intracluster light (ICL) using a surface brightness (SB) cut, a luminosity cut, excess light above a de Vaucouleurs profile, or a double Sersic decomposition. Assuming that all light above M{<}-21.85g'mag is attributable to the ICL, we find that an average fraction of f_ICL_^MT^=71+/-22% of all diffuse light centered on the BCG belongs to the ICL. Likewise, if we assume that all light fainter than SB>27g'mag/arcsec^2^ belongs to the ICL, the average ICL fraction is f_ICL_^SB27^=34+/-19% . After fitting a de Vaucouleurs profile to the inner parts of the SB profile, we detect excess light at large radii, corresponding to an average ICL fraction of f_ICL_^DV^=48+/-20% . Finally, by decomposing the SB profile into two Sersic functions, we find an average ICL fraction of f_ICL_^Sx^=52+/-21% associated with the outer Sersic component. Our measured ICL and BCG+ICL luminosities agree well with predictions from high-resolution simulations where the outer Sersic component traces the unrelaxed, accreted stellar material. BCG and ICL properties defined in this way are correlated with cluster parameters to study the coevolution of BCGs, ICL, and their host clusters. We find positive correlations between BCG+ICL brightness and cluster mass, cluster velocity dispersion, cluster radius, and integrated satellite brightness, confirming that BCG/ICL growth is indeed coupled with cluster growth. On average, the ICL is better aligned than the BCG with the host cluster in terms of position angle, ellipticity, and centering. That makes it a potential dark-matter tracer.
4702. WZ Cyg BVRI light curves
ID:
ivo://CDS.VizieR/J/AJ/142/12
Title:
WZ Cyg BVRI light curves
Short Name:
J/AJ/142/12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new multiband CCD photometry for WZ Cyg made on 22 nights in two observing seasons of 2007 and 2008. Our light-curve synthesis indicates that the system is in poor thermal contact with a fill-out factor of 4.8% and a temperature difference of 1447K. Including our 40 timing measurements, a total of 371 times of minimum light spanning more than 112yr were used for a period study. Detailed analysis of the O-C diagram showed that the orbital period has varied by a combination of an upward parabola and a sinusoid.
4703. XDEEP2 survey catalog
ID:
ivo://CDS.VizieR/J/ApJS/202/6
Title:
XDEEP2 survey catalog
Short Name:
J/ApJS/202/6
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the X-ray point-source catalog produced from the Chandra Advanced CCD Imaging Spectrometer (ACIS-I) observations of the combined ~3.2deg^2^ DEEP2 (XDEEP2) survey fields, which consist of four ~0.7-1.1deg^2^ fields. The combined total exposures across all four XDEEP2 fields range from ~10ks to 1.1Ms. We detect X-ray point sources in both the individual ACIS-I observations and the overlapping regions in the merged (stacked) images. We find a total of 2976 unique X-ray sources within the survey area with an expected false-source contamination of ~30 sources (<~1%). Additionally, we present a Bayesian-style method for associating the X-ray sources with optical photometric counterparts in the DEEP2 catalog (complete to R_AB_<25.2) and find that 2126 (~71.4%+/-2.8%) of the 2976 X-ray sources presented here have a secure optical counterpart with a <~6% contamination fraction. We provide the DEEP2 optical source properties (e.g., magnitude, redshift) as part of the X-ray-optical counterpart catalog.
4704. X-emitting stars identified from the RASS/SDSS
ID:
ivo://CDS.VizieR/J/ApJS/181/444
Title:
X-emitting stars identified from the RASS/SDSS
Short Name:
J/ApJS/181/444
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey of the entire sky. Combining the RASS Bright and Faint Source Catalogs (Cat. <IX/10>, 1RXS and <IX/29>) yields an average of about three X-ray sources per square degree. However, while X-ray source counterparts are known to range from distant quasars to nearby M dwarfs, the RASS data alone are often insufficient to determine the nature of an X-ray source. As a result, large-scale follow-up programs are required to construct samples of known X-ray emitters. We use optical data produced by the Sloan Digital Sky Survey (SDSS) to identify 709 stellar X-ray emitters cataloged in the RASS and falling within the SDSS Data Release 1 footprint. Most of these are bright stars with coronal X-ray emission unsuitable for SDSS spectroscopy, which is designed for fainter objects (g>15[mag]). Instead, we use SDSS photometry, correlations with the Two Micron All Sky Survey and other catalogs, and spectroscopy from the Apache Point Observatory 3.5m telescope to identify these stellar X-ray counterparts. Our sample of 707 X-ray-emitting F, G, K, and M stars is one of the largest X-ray-selected samples of such stars. We identify 17 new X-ray-emitting DA (hydrogen) WDs, of which three are newly identified WDs. We report on follow-up observations of three candidate cool X-ray-emitting WDs (one DA and two DB (helium) WDs); we have not confirmed X-ray emission from these WDs.
4705. 2018-2019 Xinglong BVR photometry of V0599 Aur
ID:
ivo://CDS.VizieR/J/AJ/160/62
Title:
2018-2019 Xinglong BVR photometry of V0599 Aur
Short Name:
J/AJ/160/62
Date:
08 Dec 2021
Publisher:
CDS
Description:
Combining all available photometric data from various surveys and literature with our observations, we present 10 sets of light curves for the eclipsing binary V0599 Aur covering a timescale of 20 yr. During the last two decades, the O'Connell effect continuously varied and went through at least two flips between positive and negative effects. The photometric solutions from our two sets of multicolored light curves show that V0599 Aur is a W-type shallow contact binary with an active spot on the secondary. Its absolute parameters are determined by combining the Gaia distance with the photometric solutions. The period investigation reveals a secular decrease and a cyclic variation in its orbital period. The former mainly originates from the mass transfer from the more massive secondary to the less massive primary. The latter can be preferentially explained as a result of cyclic magnetic activity of the secondary, with three observational supports: (1) the existence and evolution of an active spot suggested by the long-term photometry, (2) periodic variation in both the O'Connell effect and relative luminosity, and (3) weak correlations between O'Connell effect/relative luminosity changes and cyclic period variation. Together with the cyclic period variation and its theoretical reasonability by Applegate's mechanism, we suggest that the secondary of V0599 Aur is a solar-type magnetic-activity star with an approximately 11 yr active cycle. Furthermore, by combining the secular period decrease with the Roche-lobe model, we infer that V0599 Aur is evolving from the marginal contact state controlled by thermal relaxation oscillation theory to the overcontact state.
4706. Xinglong optical spectra of UGC3223 in 4 epochs
ID:
ivo://CDS.VizieR/J/AJ/159/245
Title:
Xinglong optical spectra of UGC3223 in 4 epochs
Short Name:
J/AJ/159/245
Date:
21 Oct 2021
Publisher:
CDS
Description:
The discovery of spectral type transition of active galactic nuclei (AGNs), the so-called "changing-look" (CL) phenomenon, challenges the widely accepted AGN paradigm, not only in the orientation-based unified model, but also in the standard disk model. In past decades, only a couple of nearby repeat changing-look active galactic nuclei (CL-AGNs) have been identified. Here we report spectroscopic observations of UGC3223 over the course of 18yr, from 2001 onwards. Combining the spectrum taken in 1987 by Stirpe, we have witnessed its type transitions from 1.5 to 2.0 to 1.8 over 32yr, and captured a long-lived (at least 10 yr) thorough "turn-off" state with a spectrum typical of a Seyfert 2 galaxy. The long-term thorough turn-off state probably suggests a once-dormant and an awakening central engine in UGC3223. We argue that the (dis)appearance of the broad Balmer emission lines can be explained by the disk-wind broad-line region model given the evolution of the calculated Eddington ratio of accretion of the supermassive black hole.
4707. Xinglong spectra of two changing-look SDSS AGNs
ID:
ivo://CDS.VizieR/J/ApJ/887/15
Title:
Xinglong spectra of two changing-look SDSS AGNs
Short Name:
J/ApJ/887/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report a spectroscopic identification of two new changing-look active galactic nuclei (CL-AGNs): SDSSJ104705.16+544405.8 and SDSSJ120447.91+170256.8, both with a "turn-off" type transition from type-1 to type-1.8/1.9. The identification is arrived at through a follow-up spectroscopic observation of the five CL-AGNs candidates that are extracted from the sample recently released in MacLeod+ (2019, J/ApJ/874/8). The candidates are extracted by the authors from the Sloan Digit Sky Survey Data Release 7, and are spectroscopically confirmed quasars with large amplitude variability. By compiling a sample of 26 previously identified CL-AGNs, we confirm the claim by MacLeod+ that CL-AGNs tend to be biased against a low Eddington ratio, and identify an overlap between the CL-AGNs at their dim state and the so-called intermediate-type AGNs. The overlap implies that there two populations of the intermediate-type AGNs with different origins. One is due to the torus orientation effect, and the other to the intrinsic change of the accretion rate of the central supermassive black holes.
4708. xi Tau UBV and MOST light curves
ID:
ivo://CDS.VizieR/J/A+A/594/A55
Title:
xi Tau UBV and MOST light curves
Short Name:
J/A+A/594/A55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Compact hierarchical systems are important because the effects caused by the dynamical interaction among its members occur ona human timescale. These interactions play a role in the formation of close binaries through Kozai cycles with tides. One such system is xi Tauri: it has three hierarchical orbits: 7.14d (eclipsing components Aa, Ab), 145d (components Aa+Ab, B), and 51yr (components Aa+Ab+B, C). We aim to obtain physical properties of the system and to study the dynamical interaction between its components. Our analysis is based on a large series of spectroscopic photometric (including space-borne) observations and long-baseline optical and infrared spectro-interferometric observations. We used two approaches to infer the system properties: a set of observation-specific models, where all components have elliptical trajectories, and an N-body model, which computes the trajectory of each component by integrating Newton's equations of motion.
4709. XMM AGN optical-UV luminosities
ID:
ivo://CDS.VizieR/J/A+A/539/A48
Title:
XMM AGN optical-UV luminosities
Short Name:
J/A+A/539/A48
Date:
21 Oct 2021
Publisher:
CDS
Description:
Active galactic nuclei (AGN) emit radiation over a wide range of wavelengths, with a peak of emission in the far-UV region of the electromagnetic spectrum, a spectral region that is historically difficult to observe. Using optical, GALEX UV, and XMM-Newton data we derive the spectral energy distribution (SED) from the optical/UV to X-ray regime of a sizeable sample of AGN. The principal motivation is to investigate the relationship between the optical/UV emission and the X-ray emission and provide bolometric corrections to the hard X-ray (2-10keV) energy range, k_bol_, the latter being a fundamental parameter in current physical cosmology.
4710. 3XMM-DR4 QSO candidates at 3<z<5.5
ID:
ivo://CDS.VizieR/J/PAZh/42/313
Title:
3XMM-DR4 QSO candidates at 3<z<5.5
Short Name:
J/PAZh/42/313
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalog of quasar candidates at redshifts 3<z<5.5 is presented. These candidates have been selected among X-ray sources in the XMM-Newton Serendipitous Source Catalog (3XMM-DR4) in the 0.5-2keV band, located at high galactic latitudes |b|>20deg in the Sloan Digital Sky Survey (SDSS) area. The total overlapping area is about 300 sq. deg. The SDSS, 2MASS and WISE photometric catalogs were used. Only SDSS point sources were considered. X-ray sources having an optical counterpart with magnitude error in SDSS z band of less than 0.2 and color i-z<0.6 were chosen. Their photometric redshifts were determined with the EAZY code using a library of spectral templates. A sample of quasar candidates with photometric redshifts in the range 2.75<z<5.5 has been composed. Objects whose spectral energy distributions are better described by stellar templates have been excluded. The selection completeness of known quasars is about 80%. The normalized median absolute deviation of the differences between the photometric and spectroscopic redshifts of known quasars is 0.07 (with 9% outliers). The sky density of quasar candidates in our sample is 1.5 times that of the spectroscopic SDSS sample in the same fields. Follow-up spectroscopy should clarify the purity of the sample.