共查询到20条相似文献，搜索用时 31 毫秒
1.
F. W. Baier 《Astronomische Nachrichten》1979,300(5):243-255
The number density distributions for further 10 clusters of galaxies were derived by counting galaxies on the red Palomar Sky Survey prints. For 6 clusters the radial number density distribution and the radial cumulative galaxy distribution were derived. 相似文献
2.
F. W. Baier 《Astronomische Nachrichten》1980,301(4):165-175
The number density distributions for further 13 cluster of galaxies are derived by counting galaxies on the red Palomar Sky Survey prints. For these clusters the radial number density distributions and the radial cumulative galaxy distribution are derived. 相似文献
3.
The number-density distributions of further 9 clusters of galaxies were derived by counting galaxies on the red Palomar Sky Survey prints. For all the clusters the radial number density distribution and the radial cumulative galaxy distribution were calculated. 相似文献
4.
Frank C. van den Bosch Xiaohu Yang H. J. Mo Peder Norberg 《Monthly notices of the Royal Astronomical Society》2005,356(4):1233-1248
Using detailed mock galaxy redshift surveys (MGRSs) we investigate the abundance and radial distribution of satellite galaxies. The mock surveys are constructed using large numerical simulations and the conditional luminosity function (CLF), and are compared against data from the Two Degree Field Galaxy Redshift Survey (2dFGRS). We use Monte Carlo Markov chains to explore the full posterior distribution of the CLF parameter space, and show that the average relation between light and mass is tightly constrained and in excellent agreement with our previous models and with that of Vale & Ostriker. The radial number density distribution of satellite galaxies in the 2dFGRS reveals a pronounced absence of satellites at small projected separations from their host galaxies. This is (at least partly) owing to the overlap and merging of galaxy images in the 2dFGRS parent catalogue. Owing to the resulting close-pair incompleteness we are unfortunately unable to put meaningful constraints on the radial distribution of satellite galaxies; the data are consistent with a radial number density distribution that follows that of the dark matter particles, but we cannot rule out alternatives with a constant number density core. Marginalizing over the full CLF parameter space, we show that in a ΛCDM concordance cosmology the observed abundances of host and satellite galaxies in the 2dFGRS indicate a power spectrum normalization of σ8 ≃ 0.7 . The same cosmology but with σ8 = 0.9 is unable to match simultaneously the abundances of host and satellite galaxies. This confirms our previous conclusions based on the pairwise peculiar velocity dispersions and the group multiplicity function. 相似文献
5.
We compare the radial distributions of known localized gamma-ray bursts (GRBs) relative to the centers of their host galaxies with the distributions of known objects in nearby galaxies (supernovae of various types, X-ray binaries), the hypothetical dark-matter profiles, and the distribution of luminous matter in galaxies in the model of an exponential disk. By comparing the moments of empirical distributions, we show that the radial distribution of GRBs in galaxies differs significantly from that of other sources. We suggest a new statistical method for comparing empirical samples that is based on estimating the number of objects within a given radius. The exponential disk profile was found to be in best agreement with the radial distribution of GRBs. The distribution of GRBs relative to the centers of their host galaxies also agrees with the dark matter profile at certain model parameters. 相似文献
6.
Takashi Hasegawa † Ken-ichi Wakamatsu ‡ Matthew Malkan ‡ Kazuhiro Sekiguchi John W. Menzies Quentin A. Parker Jun Jugaku Hiroshi Karoji Sadanori Okamura 《Monthly notices of the Royal Astronomical Society》2000,316(2):326-344
The large-scale structure around the Ophiuchus cluster of galaxies in the vicinity of the Galactic Centre ( l =05, b =95, cz =8500 km s−1 ) is investigated on the basis of a galaxy survey and spectroscopic observations made for a 12°×17° area. The galaxy survey was performed using six ESO/SERC Sky Survey Atlas films, and 4021 galaxies were detected in total. Recession velocities were newly obtained for 179 galaxies to make the total number of galaxies in the survey area with known velocities 219.
In the distribution of bright galaxies, we identified seven new clumps of galaxies. Comparing the surface number density of bright galaxies with the Galactic extinction, which is estimated from the 100‐μm flux density in the IRAS Sky Survey Atlas, we demonstrate that the seven clumps are not spurious as a result of the inhomogeneity of the Galactic extinction. Among the seven clumps, two are found to be clusters and four to be groups on the basis of the histogram of recession velocities and the number of member galaxies. The Ophiuchus cluster, two newly identified clusters, and four groups are all concentrated at 9000 km s−1 . Field galaxies are also distributed centred at 8500 km s−1 . Hence field galaxies occupy a common three-dimensional region with galaxies in the clusters and groups, and altogether they form a large-scale structure of supercluster size. As opposed to the overdensity in the supercluster region, the mean number density of galaxies in the velocity range 0–5000 km s−1 is only 25 per cent of the mean number density of the Universe, comparable with the density of the well-known Böotes void. Hence this nearby three-dimensional region in Ophiuchus is a void of galaxies also. 相似文献
In the distribution of bright galaxies, we identified seven new clumps of galaxies. Comparing the surface number density of bright galaxies with the Galactic extinction, which is estimated from the 100‐μm flux density in the IRAS Sky Survey Atlas, we demonstrate that the seven clumps are not spurious as a result of the inhomogeneity of the Galactic extinction. Among the seven clumps, two are found to be clusters and four to be groups on the basis of the histogram of recession velocities and the number of member galaxies. The Ophiuchus cluster, two newly identified clusters, and four groups are all concentrated at 9000 km s
7.
The number-density distribution of four ABELL -clusters in the region of the Hercules supercluster was derived by counting galaxies on the red Palomar Sky Survey prints. For one isolated cluster the radial number-density distribution and the radial cumulative galaxy distribution were calculated. 相似文献
8.
E. H. Nikogossian 《Astrophysics》2000,43(1):32-39
The hierarchical structure of the clusters of galaxies A 999, A 1016, and A 1142, which are part of one supercluster, is investigated.
The HTree method is used to determine that A 999 and A 1016 are a single, dynamically bound system consisting of two “cores”
and a common field of galaxies. The composition of the “cores” includes almost all the E and S0 galaxies, the luminosity function
of which is very nearly Gaussian. It is also established that the cluster A 1142 has a nonuniform structure, both in density
distribution and in radial velocity distribution. The location of the maxima in density and in the radial velocity distribution
correlates with the galaxies that are sources of radio and x-ray emission.
Translated from Astrofizika, Vol. 43, No. 1, pp. 45-54, January–March, 2000. 相似文献
9.
Ignacio Ferreras Thorsten Lisker Anna Pasquali Sadegh Khochfar Sugata Kaviraj 《Monthly notices of the Royal Astronomical Society》2009,396(3):1573-1578
The evolution of number density, size and intrinsic colour is determined for a volume-limited sample of visually classified early-type galaxies selected from the Hubble Space Telescope /Advanced Camera for Surveys images of the Great Observatories Origins Deep Survey (GOODS) North and South fields (version 2). The sample comprises 457 galaxies over 320 arcmin2 with stellar masses above 3 × 1010 M⊙ in the redshift range 0.4 < z < 1.2 . Our data allow a simultaneous study of number density, intrinsic colour distribution and size. We find that the most massive systems (≳3 × 1011 M⊙ ) do not show any appreciable change in comoving number density or size in our data. Furthermore, when including the results from 2dF galaxy redshift survey, we find that the number density of massive early-type galaxies is consistent with no evolution between z = 1.2 and 0, i.e. over an epoch spanning more than half of the current age of the Universe. We find large discrepancies between the predictions of semi-analytic models. Massive galaxies show very homogeneous intrinsic colour distributions, with nearly flat radial colour gradients, but with a significant negative correlation between stellar mass and colour gradient, such that red cores appear predominantly in massive galaxies. The distribution of half-light radii – when compared to z ∼ 0 and z > 1 samples – is compatible with the predictions of semi-analytic models relating size evolution to the amount of dissipation during major mergers. 相似文献
10.
R. A. Angiras † C. J. Jog † A. Omar † K. S. Dwarakanath † 《Monthly notices of the Royal Astronomical Society》2006,369(4):1849-1857
The H i surface density maps for a sample of 18 galaxies in the Eridanus group are Fourier analysed. This analysis gives the radial variation of the lopsidedness in the H i spatial distribution. The lopsidedness is quantified by the Fourier amplitude A 1 of the m = 1 component normalized to the average value. It is also shown that in the radial region where the stellar disc and H i overlap, their A 1 coefficients are comparable. All the galaxies studied show significant lopsidedness in H i . The mean value of A 1 in the inner regions of the galaxies (1.5–2.5 scalelengths) is ≥ 0.2. This value of A 1 is twice the average value seen in the field galaxies. Also, the lopsidedness is found to be smaller for late-type galaxies; this is opposite to the trend seen in the field galaxies. These two results indicate a different physical origin for disc lopsidedness in galaxies in a group environment compared to the field galaxies. Further, a large fraction (∼30 per cent) shows a higher degree of lopsidedness ( A 1 ≥ 0.3). It is also seen that the disc lopsidedness increases with the radius as demonstrated in earlier studies, but over a radial range that is two times larger than done in the previous studies. The average lopsidedness of the halo potential is estimated to be ∼10 per cent, assuming that the lopsidedness in H i disc is due to its response to the halo asymmetry. 相似文献
11.
The number-density distribution in ten clusters of galaxies was derived by counting galaxies on the red Palomar Sky Survey prints. For seven isolated clusters the radial number-density distribution and the radial cumulative galaxy distribution were calculated. 相似文献
12.
The initial principles of a method for analyzing the spatial distribution of visible matter in the universe with structures
on size scales of thousands of Mpc are discussed. This method is based on analyzing the distribution N(z) of the photometric
redshifts of galaxies in deep fields using large bins Δ z=0.1–0.3. Fluctuations in the numbers of galaxies in these bins in
terms of redshifts are caused by Poisson noise, correlated structures, and systematic errors in estimating photo-z. This method
involves covering a sufficiently large region of the celestial sphere with a grid of deep multi-band surveys with a cell size
on the order of 10o×10o, with deep fields of size ∼10'×10' observed with 3-10 meter telescopes at its nodes. The distribution
of the photometric redshifts of the galaxies within each deep field will yield information on the radial extent of superlarge
structures, while comparing the radial distributions in neighboring fields will yield information on the tangential extent
of these structures. A necessary element of this method is an analysis of possible distortions in the radial distributions
of the galaxies associated with the technique for evaluating the photometric redshifts. 相似文献
13.
A detailed reinvestigation of the Coma cluster basing on enlarged observational material of number density distributions and radial velocities of galaxies as well as radio and x-ray data is performed and supports our previous conclusion that this cluster possesses a substructure. This substructure is in the south-western region of the cluster and produces the impression of an elongated cluster structure in the direction of the bridge between Coma and A 1367. A 1656 seems to be a cD-like cluster with NGC 4874 as the only dominating giant central galaxy. 相似文献
14.
Yu. L. Bukhmastova 《Astronomy Letters》2007,33(6):355-367
Based on the SDSS catalog, we have found new close quasar—galaxy pairs. We analyze the radial distribution of quasars from pairs around galaxies of different types. We show that the quasars from pairs follow the density profile of halo globular clusters. This is new observational evidence that the quasars projected onto the halos of galaxies are magnified by gravitational lensing by halo globular clusters. 相似文献
15.
The initial principles of a method for analyzing the spatial distribution of visible matter in the universe with structures on size scales of thousands of Mpc are discussed. This method is based on analyzing the distribution N(z) of the photometric redshifts of galaxies in deep fields using large bins Δ z=0.1–0.3. Fluctuations in the numbers of galaxies in these bins in terms of redshifts are caused by Poisson noise, correlated structures, and systematic errors in estimating photo-z. This method involves covering a sufficiently large region of the celestial sphere with a grid of deep multi-band surveys with a cell size on the order of 10º×10º, with deep fields of size ～10'×10' observed with 3-10 meter telescopes at its nodes. The distribution of the photometric redshifts of the galaxies within each deep field will yield information on the radial extent of superlarge structures, while comparing the radial distributions in neighboring fields will yield information on the tangential extent of these structures. A necessary element of this method is an analysis of possible distortions in the radial distributions of the galaxies associated with the technique for evaluating the photometric redshifts. 相似文献
16.
17.
I. D. Karachentsev D. I. Makarov V. E. Karachentseva O. V. Melnyk 《Astrophysical Bulletin》2011,66(1):1-27
We present a catalog of 520 most isolated nearby galaxies with angular velocities V
LG
< 3500 km/s, covering the entire sky. This population of “space orphans” makes up 4.8% among 10 900 galaxies with measured
radial velocities. We describe the isolation criterion used to select our sample, called the “Local Orphan Galaxies”(LOG),
and discuss their basic optical and HI properties. A half of the LOG catalog is occupied by the Sdm, Im and Ir morphological
type galaxies without a bulge. The median ratio M
gas/M
star in the LOG galaxies exceeds 1. The distribution of the catalog galaxies on the sky looks uniform with some signatures of
a weak clustering on the scale of about 0.5 Mpc. The LOG galaxies are located in the regions where the mean local density
of matter is approximately 50 times lower than the mean global density. We indicate a number of LOG galaxies with distorted
structures, which may be the consequence of interaction of isolated galaxies with massive dark objects. 相似文献
18.
Images of the Hubble Ultra Deep Field are analyzed to obtain a catalog of galaxies for which the angular sizes, surface brightness, photometric redshifts, and absolute magnitudes are found. The catalog contains a total of about 4000 galaxies identified at a high signal-to-noise ratio, which allows the cosmological relations angular size—redshift and surface brightness-redshift to be analyzed. The parameters of the evolution of linear sizes and surface brightness of distant galaxies in the redshift interval 0.5–6.5 are estimated in terms of a grid of cosmological models with different density parameters (Ω V ; Ω m ). The distribution of photometric redshifts of galaxies is analyzed and possible superlarge inhomogeneities in the radial distribution of galaxies are found with scale lengths as large as 2000 Mpc. 相似文献
19.
We present an analysis of the chiral property of 667 spiral and barred spiral galaxies in the Local Supercluster (radial velocity
<3 000 km s−1). The arms of a galaxy (spiral or barred spiral) can be distinguished according to their orientation (leading or trailing)
relative to the direction of the rotation. We use environment of each galaxy as a subsample in order to study the chiral property
of galaxies. In addition, equatorial position angle distributions of leading and trailing arm galaxies are studied. We classify
our database according as their morphology, diameters, radial velocities, axial ratios and magnitudes. The distribution of
trailing and leading arm galaxies in the Local Supercluster is found homogeneous. A significant dominance of either trailing
or leading structures is noticed within the Virgo cluster region, suggesting that the aggregation of these structures might
have already started there. The rotation axes of the galaxies in the Virgo cluster is found to lie in the equatorial plane.
Chirality of galaxies is found strong for the subsamples that showed a random alignment in the equatorial position angle distribution.
Possible explanations of the results will be presented. 相似文献
20.
F. W. Baier 《Astronomische Nachrichten》1979,300(2):85-97
The number-density distributions of further 10 clusters of galaxies were derived by counting galaxies on the red Palomar Sky Survey prints. For all the clusters the radial number-density distribution and the radial cumulative galaxy distribution were calculated. 相似文献