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- ID:
- ivo://CDS.VizieR/J/A+A/459/L1
- Title:
- Supercluster sample from SDSS DR4
- Short Name:
- J/A+A/459/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compile a supercluster sample using the Sloan Digital Sky Survey Data Release 4, and reanalyse supercluster samples found for the 2dF Galaxy Redshift Survey and for simulated galaxies of the Millennium Run. We find for all supercluster samples Density Field (DF) clusters, which represent high-density peaks of the class of Abell clusters, and use median luminosities of richness class 1 DF-clusters to calculate relative luminosity functions. We show that the fraction of very luminous superclusters in real samples is about five times greater than in simulated samples. Superclusters are generated by large-scale density perturbations that evolve very slowly. The absence of very luminous superclusters in simulations can be explained either by incorrect treatment of large-scale perturbations, or by some yet unknown processes in the very early Universe.
18313. Superclusters and voids
- ID:
- ivo://CDS.VizieR/J/MNRAS/269/301
- Title:
- Superclusters and voids
- Short Name:
- J/MNRAS/269/301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the whole-sky distribution of rich clusters of galaxies up to the distance z~0.1 and present catalogues of superclusters and cluster-defined voids. The data on clusters, superclusters and voids show the presence of the characteristic scale of 130h^-1^Mpc in the supercluster-void network, found earlier by Broadhurst et al. (1990Natur.343..726B) from a one-dimensional study. This scale has been detected in the distribution of clusters of richnesses R=0 and R>=1. We perform tests to study the influence of projection effects. The clusters that do not belong to superclusters are located in the vicinity of superclusters and form their outlying parts. We compare the distribution of ACO clusters with that of APM clusters. The APM clusters determine a smaller scale: 100h^-1^Mpc. We discuss the possible reasons for this difference.
- ID:
- ivo://CDS.VizieR/J/AJ/122/2222
- Title:
- Superclusters of Abell and X-ray clusters
- Short Name:
- J/AJ/122/2222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of superclusters of Abell clusters out to a redshift of z_lim_=0.13, a catalog of X-ray clusters located in superclusters determined by Abell clusters, and a list of additional superclusters of X-ray clusters. We investigate the distribution of X-ray selected clusters of galaxies with respect to superclusters determined by Abell clusters of galaxies and show that the distribution of X-ray clusters follows the supercluster-void network determined by Abell clusters. We find that X-ray clusters are more strongly clustered than other clusters: the fraction of X-ray clusters is higher in rich superclusters, and the fraction of isolated X-ray clusters is lower than the fraction of isolated Abell clusters. Poor, non-Abell X-ray clusters follow the supercluster-void network as well: these clusters are embedded in superclusters determined by Abell clusters and populate filaments between them. This catalogue supersedes J/A+AS/123/119
- ID:
- ivo://CDS.VizieR/J/A+A/462/811
- Title:
- Superclusters of galaxies from 2dF
- Short Name:
- J/A+A/462/811
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the 2dF Galaxy Redshift Survey data to compile catalogues of superclusters for the Northern and Southern regions of the 2dFGRS, altogether 543 superclusters at redshifts 0.009<z<0.2. We apply the density field method using smoothing with an Epanechnikov kernel of radius 8Mpc. We derive positions of the highest luminosity density peaks and find the most luminous cluster in the vicinity of the peak, this cluster is considered as the main cluster and its brightest galaxy the main galaxy of the supercluster. In catalogues we give equatorial coordinates and distances of superclusters as determined by positions of their main clusters. We also calculate the expected total luminosities of the superclusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/172
- Title:
- "Super-deblended" dust emission in galaxies. I.
- Short Name:
- J/ApJ/853/172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new technique to measure multi-wavelength "super-deblended" photometry from highly confused images, which we apply to Herschel and ground-based far-infrared (FIR) and (sub-)millimeter (mm) data in the northern field of the Great Observatories Origins Deep Survey (GOODS-N). There are two key novelties. First, starting with a large database of deep Spitzer 24{mu}m and VLA 20cm detections that are used to define prior positions for fitting the FIR/submm data, we perform an active selection of useful priors independently at each frequency band, moving from less to more confused bands. Exploiting knowledge of redshift and all available photometry, we identify hopelessly faint priors that we remove from the fitting pool. This approach significantly reduces blending degeneracies and allows reliable photometry to be obtained for galaxies in FIR+mm bands. Second, we obtain well-behaved, nearly Gaussian flux density uncertainties, individually tailored to all fitted priors for each band. This is done by exploiting extensive simulations that allow us to calibrate the conversion of formal fitting uncertainties to realistic uncertainties, depending on directly measurable quantities. We achieve deeper detection limits with high fidelity measurements and uncertainties at FIR+mm bands. As an illustration of the utility of these measurements, we identify 70 galaxies with z>=3 and reliable FIR+mm detections. We present new constraints on the cosmic star formation rate density at 3<z<6, finding a significant contribution from z>=3 dusty galaxies that are missed by optical-to-near-infrared color selection. Photometric measurements for 3306 priors, including more than 1000 FIR+mm detections, are released publicly with our catalog.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/5
- Title:
- Superflares of Kepler stars. I.
- Short Name:
- J/ApJS/209/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By extending our previous study by Maehara et al. (2012, Cat. J/other/Nat/485.478), we searched for superflares on G-type dwarfs (solar-type stars) using Kepler data for a longer period (500 days) than that (120 days) in our previous study. As a result, we found 1547 superflares on 279 G-type dwarfs, which is much more than the previous 365 superflares on 148 stars. Using these new data, we studied the statistical properties of the occurrence rate of superflares, and confirmed the previous results, i.e., the occurrence rate (dN/dE) of superflares versus flare energy (E) shows a power-law distribution with dN/dE{prop.to}E^-{alpha}^, where {alpha}~2. It is interesting that this distribution is roughly similar to that for solar flares. In the case of the Sun-like stars (with surface temperature 5600-6000K and slowly rotating with a period longer than 10 days), the occurrence rate of superflares with an energy of 10^34^-10^35^erg is once in 800-5000yr. We also studied long-term (500 days) stellar brightness variation of these superflare stars and found that in some G-type dwarfs the occurrence rate of superflares was extremely high, ~57 superflares in 500 days (i.e., once in 10 days). In the case of Sun-like stars, the most active stars show a frequency of one superflare (with 10^34^erg) in 100 days. There is evidence that these superflare stars have extremely large starspots with a size about 10 times larger than that of the largest sunspot. We argue that the physical origin of the extremely high occurrence rate of superflares in these stars may be attributed to the existence of extremely large starspots.
- ID:
- ivo://CDS.VizieR/J/other/Nat/485.478
- Title:
- Superflares on solar-type stars
- Short Name:
- J/other/Nat/485.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Solar flares are caused by the sudden release of magnetic energy stored near sunspots. They release 10<SUP>29</SUP> to 10<SUP>32</SUP>ergs of energy on a timescale of hours. Similar flares have been observed on many stars, with larger 'superflares' seen on a variety of stars, some of which are rapidly rotating and some of which are of ordinary solar type. The small number of superflares observed on solar-type stars has hitherto precluded a detailed study of them. Here we report observations of 365 superflares, including some from slowly rotating solar-type stars, from about 83,000 stars observed over 120 days. Quasi-periodic brightness modulations observed in the solar-type stars suggest that they have much larger starspots than does the Sun. The maximum energy of the flare is not correlated with the stellar rotation period, but the data suggest that superflares occur more frequently on rapidly rotating stars. It has been proposed that hot Jupiters may be important in the generation of superflares on solar-type stars, but none have been discovered around the stars that we have studied, indicating that hot Jupiters associated with superflares are rare.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/46
- Title:
- Superflares on solar-type stars from TESS first year
- Short Name:
- J/ApJ/890/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Superflares, which are strong explosions on stars, have been well studied with the progress of spacetime-domain astronomy. In this work, we present the study of superflares on solar-type stars using Transiting Exoplanet Survey Satellite (TESS) data. Thirteen sectors of observations during the first year of the TESS mission covered the southern hemisphere of the sky, containing 25734 solar-type stars. We verified 1216 superflares on 400 solar-type stars through automatic search and visual inspection with 2 minute cadence data. Our result suggests a higher superflare frequency distribution than the result from Kepler. This may be because the majority of TESS solar-type stars in our data set are rapidly rotating stars. The power-law index {gamma} of the superflare frequency distribution (dN/dE{propto}E^-{gamma}^) is constrained to be {gamma}=2.16+/-0.10, which is a little larger than that of solar flares but consistent with the results from Kepler. Because only seven superflares of Sun-like stars are detected, we cannot give a robust superflare occurrence frequency. Four stars were accompanied by unconfirmed hot planet candidates. Therefore, superflares may possibly be caused by stellar magnetic activities instead of planet-star interactions. We also find an extraordinary star, TIC43472154, which exhibits about 200 superflares per year. In addition, the correlation between the energy and duration of superflares (T_duration_{propto}E^{beta}^) is analyzed. We derive the power-law index to be {beta}=0.42+/-0.01, which is a little larger than {beta} = 1/3 from the prediction according to magnetic reconnection theory.
- ID:
- ivo://CDS.VizieR/J/ApJS/75/241
- Title:
- Supergalactic plane redshift survey
- Short Name:
- J/ApJS/75/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Redshift measurements, about 1000 of which are new, are presented for 1314 galaxies in a survey toward the apex of the large-scale streaming flow for ellipticals.