共查询到20条相似文献，搜索用时 62 毫秒
1.
2.
E. M. Burbidge T. A. Barlow R. D. Cohen V. T. Junkkarinen D. S. Womble 《Astrophysics and Space Science》1989,157(1-2):263-269
The properties of low-to-medium ionization gaseous haloes around galaxies are briefly reviewed. New observations concerning such haloes are presented. For the galaxy-QSO pair in the field of the radio source 3C303, the higher-redshift QSO has been found to show Mgii absorption at the lowre redshift of the faint nearby galaxy. Secondly, new data are presented on one of the galaxies in the environment of the well-known BL Lac object AO 0235+164. 相似文献
3.
Evidence is presented indicating the non-random alignment of spiral galaxies in the Local Supercluster. The form of this effect is such that the spin angular momentum vectors of intermediate-type spirals are coherently aligned in space. The results suggest the formation of galaxies in the Local Supercluster according to the fragmentation hypothesis.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
4.
A. T. Kalloglyan 《Astrophysics》1995,38(1):22-26
On the basis of extensive observational material it is statistically demonstrated that dwarf galaxies appear more often around barred galaxies than around normal spiral galaxies. Moreover, the more barred spiral galaxies there are in a given region, the more dwarf galaxies are found there as well.Translated from Astrofizika, Vol. 38, No. 1, pp. 45–53, January–March, 1995. 相似文献
5.
Smita Mathur 《Monthly notices of the Royal Astronomical Society》2000,314(4):L17-L20
Narrow Line Seyfert 1 galaxies (NLS1s) are intriguing owing to their continuum as well as emission-line properties. The observed peculiar properties of the NLS1s are believed to be as a result of an accretion rate close to the Eddington limit. As a consequence of this, for a given luminosity, NLS1s have smaller black hole (BH) masses compared with normal Seyfert galaxies. Here we argue that NLS1s might be Seyfert galaxies in their early stage of evolution and as such may be low-redshift, low-luminosity analogues of high-redshift quasars. We propose that NLS1s may reside in rejuvenated, gas-rich galaxies. We also argue in favour of collisional ionization for production of Fe ii in active galactic nuclei. 相似文献
6.
Galaxy evolution by interaction‐driven transformation is probably highly efficient in groups of galaxies. Dwarf galaxies with their shallow potential are expected to reflect the interaction most prominently in their observable structure. The major aim of this series of papers is to establish a data base which allows to study the impact of group interaction onto the morphology and star‐forming properties of dwarf galaxies. Firstly, we present our selection rules for target groups and the morphological selection method of target dwarf member candidates. Secondly, the spectroscopic follow‐up observations with the HET are presented. Thirdly, we applied own reduction methods based on adaptive filtering to derive surface photometry of the candidates. The spectroscopic follow‐up indicate a dwarf identification success rate of roughly 55 %, and a group member success rate of about 33 %. A total of 17 new low surface‐brightness members is presented. For all candidates, total magnitudes, colours, and light distribution parameters are derived and discussed in the context of scaling relations. We point out short comings of the SDSS standard pipeline for surface photometry for these dim objects. We conclude that our selection strategy is rather efficient to obtain a sample of dim, low surface brightness members of groups of galaxies within the Virgo super‐cluster. The photometric scaling relation in these X‐ray dim, rather isolated groups does not significantly differ from those of the galaxies within the local volume. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
T. Jaakkola 《Astrophysics and Space Science》1977,49(1):99-111
82 compact galaxies with measured redshift present in systems containing partly normal galaxies have been found, using Zwicky's Catalogues and Morphological Catalogue. For them the mean residual redshift
has been obtained. The chance probability for this result is 0.015. A high frequency of compact galaxies among those with large discrepant redshift is remarked. Relatively compact normal galaxies also reveal a positive mean value of
. Redshift is correlated with magnitude in groups and pairs of compact galaxies, this depending in pairs on the linear separation and colours of the components. If a colour difference is present, the bluer member has the larger redshift in general. In contrast with the large luminosity deduced from the redshift for many field compacts, compact galaxies in systems are faint. The majority of the proposed associations between quasars and systems of normal galaxies are shown to be probably physical. 相似文献
8.
The GMRTHI 21 cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ≈ 23 Mpc, is
a loose group of ≈200 galaxies. The group extends to more than 10 Mpc in projection. The velocity dispersion of the galaxies
in the group is ≈240 km s−1. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E + S0) and 70% (Sp
+ Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ≈ 200 h. HI emission was detected from
31 galaxies. The channel rms of ≈ 1 mJy beam−1 was achieved for most of the image-cubes made with 4 h of data. The corresponding HI column density sensitivity (3σ) is ≈
1 × 1020 cm−2 for a velocity-width of ≈ 13.4 km s−1. The 3σ detection limit of HI mass is ≈ 1.2 X 107 Mpd for a line-width of 50 km s−1. Total HI images, HI velocity fields, global HI line profiles, HI mass surface densities, HI disk parameters and HI rotation
curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies.
These data will be used to study the HI and the radio continuum properties, the Tully-Fisher relations, the dark matter halos,
and the kinematical and HI lopsidedness in galaxies. 相似文献
9.
IR properties of Compact Group (CG) galaxies are presented and compared with IR properties of isolated galaxies. Despite CGs
displaying more E-S0s and optically bright galaxies, no differences are retrieved concerning FIR emission. The observed lack
of strong FIR enhancement in the CG sample is not surprising when interpreting FIR sources in CGs as accordant redshift projections,
rather than as mergers in progress.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Preliminary results of a programme aimed at investigating the presence of Hii regions around Seyfert nuclei are presented. We have detected extended zones of ionized gas around some classical Seyfert galaxies. We think that the ionizing mechanism in these extended regions is UV radiation from young stars formed in a recent burst of star formation. In many instances the objects studied show morphological disturbances arising from the interaction with nearby companion galaxies. 相似文献
11.
J.P. Willis † P.C. Hewett S.J. Warren 《Monthly notices of the Royal Astronomical Society》2001,325(3):1002-1016
We have compiled a sample of ∼ 9600 bright, i ≤18.95 , red, b J − r >2 , candidate galaxies in an area of 220 deg2 . These are luminous, L > L * , field early-type galaxies with redshifts 0.3≲ z ≲0.6 . We present a redshift catalogue of a subsample of 581 targets. The galaxies were selected according to their broad-band b J ri colours from United Kingdom Schmidt Telescope plates, and have a surface density on the sky of only ∼ 50 deg−2 . Such luminous field galaxies are virtually absent from published redshift surveys and the catalogue provides a large sample of the most luminous normal galaxies, at cosmological distances. The statistical properties of the galaxy spectra, including absorption-line and emission-line measures, are presented and a composite spectrum constructed. The nature of the sample, combined with the relatively bright apparent magnitudes, makes the galaxies suitable targets for several key investigations in galaxy evolution and cosmology. 相似文献
12.
Sixteen poor clusters of galaxies with suspected cD galaxies are studied usingV-band photographs taken with the 105 cm Kiso Schmidt telescope. Galaxian images were automatically detected using an image detection software developed for the present study. It is found from the luminosity functions that the richness of the clusters are well correlated with the optical properties of central galaxies and the X-ray luminosities of the clusters.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
13.
Toshiaki Ishizawa 《Astrophysics and Space Science》1986,119(1):221-225
Self-consistent simulations of seven groups of galaxies with halos have been performed to find a constraint upon the size of missing halos around spiral galaxies. An initial galaxy, which consists of 100 superstars, has half-mass radius 41 kpc and central velocity dispersion 235 km s–1. The simulations start from the epoch of maximum expansion. The initial conditions involve a variety of spatial distributions of galaxies, and the velocity dispersion of galaxies as would be permitted for maximum expansion. Dense groups having collapse times shorter than (2/3)H
0
–1
are shown to form multiple mergers in a Hubble timeH
0
–1
. From a comparison of the frequencies of cD galaxies, or multiple mergers, in observed and simulated groups, it is concluded that the effective radius of missing halos is less than 41 kpc.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
14.
R. A. Kandalian 《Astrophysics》1996,39(3):237-244
An analysis of a sample of OH megamaser galaxies is presented. It is shown that the dependence of LOH on LFIR (far infrared) is not quadratic, as previously assumed, but closer to linear. In megamaser galaxies, LC (radio continuum) LFIR1. Analysis of the data also shows that as the OH emission line width decreases, the absolute values of the pumping efficiency and maser amplification coefficient increase. The radio luminosity of the central component in these galaxies increases with a decrease in the ratio LFIR/LC, whereas the FIR luminosity remains constant. These results will, in all probability, force a reexamination of the questions of pumping and maser emission mechanisms in megamaser galaxies.Translated fromAstrofizika, Vol. 39, No. 3, pp. 417–429, July–September, 1996. 相似文献
15.
A sample of 230 galaxies has been compiled based on their IRAS FSC fluxes to study their multiwavelength properties and carry
out comparative analyses with other similar samples. To understand the nature of these galaxies, a comparison with a sample
of bright ULIRGs having fluxes at 60 μm fν > 1 Jy and 14 optically faint IRAS FSC galaxies is presented. This comparison shows that galaxies found by IRAS are not always
strong infrared sources and that the objects from the sample of ULIRGs represent a sample of extreme galaxies, which are very
powerful infrared sources. We have confirmed the consistency between Star Formation Rates (SFRs) calibrated based on luminosities
of the PAH feature at 7.7 μm and radio 1.4 GHz flux densities. We have estimated the extinction for our 230 objects using
SFRs calibrated from the PAH feature compared to ultraviolet flux, which shows that only 1% of the ultraviolet continuum typically
escapes extinction by dust within a starburst. 相似文献
16.
P. Best 《Astrophysics and Space Science》2003,285(1):137-142
The results of deep radio, sub-mm and X-ray observations of samples of high redshift (z∼1) clusters are presented. These reveal significant excesses of active galaxies associated with the clusters at all three wavelengths.
The cluster radio source population shows evolution consistent with the (1+z)3 evolution typical of many AGN classes. A large fraction of the AGN are hosted by apparently passive early-type galaxies,
often with a close companion. These results essentially constitute the detection of a counterpart of the Butcher-Oemler effect
for both strongly star bursting galaxies and AGN.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
We review the properties and nature of luminous high-redshift radio galaxies (HzRGs, z > 2) and the environments in which they are located. HzRGs have several distinct constituents which interact with each other—relativistic
plasma, gas in various forms, dust, stars and an active galactic nucleus (AGN). These building blocks provide unique diagnostics
about conditions in the early Universe. We discuss the properties of each constituent. Evidence is presented that HzRGs are
massive forming galaxies and the progenitors of brightest cluster galaxies in the local Universe. HzRGs are located in overdense
regions in the early Universe and are frequently surrounded by protoclusters. We review the properties and nature of these
radio-selected protoclusters. Finally we consider the potential for future progress in the field during the next few decades.
A compendium of known HzRGs is given in an appendix. 相似文献
18.
1200 strongly flattened galaxies with axis ratio b/a ≤ 0.15 were selected from the UGC catalogue, contained in the Abadumani
Merged Catalogue of Galaxies, and their properties were studied. The possibility of using strongly flattened galaxies and
several other samples of galaxies according to their morphological type as a distance indicator has been examined by the Tully-Fisher
relation. The investigation has shown that angular diameters of strongly flattened as well as flat, seen edge-on galaxies
designated as F and L in the MCG catalogue can be used for the estimation of distance moduli with accuracy O.m7. The distribution of absolute magnitudes of strongly flattened galaxies was approximated by analytic Schechter expression
with main parameters M* = -21.m2 and α = -1.0. The statistical method of the nearest companion applied to the apparent distribution of strongly flattened
galaxies has shown that these galaxies are considerably more frequently found in mixed pairs and multiple systems than spirals.
Published in Astrofizika, Vol. 41, No. 1, pp. 23–34, January-March, 1998. 相似文献
19.
The atomic and molecular hydrogen gas properties of a complete sample of Markarian galaxies with flux density at 60 µm higher than 1.95 Jy are presented. We present the improved far-infrared luminosity function of Markarian galaxies; and its comparison with other samples. We find that 40% of the bright IRAS galaxies of far-infrared luminosity higher than 1010.5
L
are Markarian galaxies. There is an absence of correlation between HI content of Markarian galaxies and current star formation activity, implying that star formation in these systems has complex structure and it is not a simple function of the HI content. On the contrary, the H2 content of Markarian galaxies is well correlated with star formation activity. It is argued that tight correlation between HI and H2 contents is a consequence of transformation of atomic hydrogen into molecular.Published in Astrofizika, Vol. 38, No. 4, pp. 636–644, October–December, 1995. 相似文献
20.
Spectroscopic observations of twelve M51-type binary galaxies with the 6-m Special Astrophysical Observatory telescope are presented. We constructed the rotation curves for the primary galaxies of each binary system and determined the line-of-sight velocities of their companions from the Hα and [N II] 6583 Å emission lines. 相似文献