The implications for galaxy formation of inflationary cosmology are reviewed. In particular, I explore some implications of the hypothesis that galaxies form from adiabatic, gaussian density fluctuations in a cold dark matter–dominated universe. Topics discussed include protogalaxies and the epoch of galaxy formation, Lyman alpha clouds, dark halos and dwarf galaxies. Finally I describe how environmental biasing may arise as a consequence of tidally induced star formation in protoclusters.

Although some theories, such as that of cold dark matter, are quite successful in explaining certain aspects of the formation of structure, we seem not to approach a satisfactory theory which can easily account for all the observational constraints on all scales. Most difficult to explain are the indicated clustering of clusters and bulk velocities on very large scales, when considered together with the structure on galactic scales and the isotropy of the microwave background. If these observations are correct, the only scenarios that can work are hybrids of certain sorts, which involve somewhat ad hoc choices of parameters; they are not the theories that would have emerged naturally from first principles, and they do not satisfy the criteria of simplicity and elegancy. I will discuss the currently popular scenarios and the apparent difficulties they face.

We describe and apply a quantitative measure of the topology of large scale structure: the genus of density contours in a smoothed density distribution. For random phase (gaussian) density fields, the mean genus per unit volume exhibits a universal dependence on threshold density, with a normalizing factor that can be calculated from the power spectrum. The topology of the observational sample is consistent with the random phase, cold dark matter model.

We have compiled a data base of V-band two-dimensional luminosity distribution for 261 galaxies in the Virgo and the Ursa Major regions (Watanabe 1983) using the 105-cm Schmidt telescope at the Kiso Observatory, Tokyo Astronomical Observatory. This is one of the largest collections of homogeneous surface photometry available to date, though the sample is biased for bright and large galaxies with m(V)≤14mag and/or D2 6≥2′. Among the sample galaxies we have selected some 200 certain members (V0<3500km/s) of the Virgo cluster and the Ursa Major clouds and performed various analyses on them to investigate systematic properties of galaxies. The two clusterings lie at nearly equal distance of (m-M)∼31.1 (Aaronson and Mould 1983). In the present paper we discuss the result of spheroid (bulge)/disk decomposition and velocity-luminosity relation for galaxies.

Although current models of galaxy formation differ widely, it seems likely that just prior to their formation, a significant fraction of the matter in the Universe was in the form of neutral hydrogen (HI) clouds at redshifts z greater than about 3, beyond which the quasar density decreases rapidly. In this paper we have taken a semi-empirical approach for estimating values of measurable parameters for a variety of scale sizes and masses expected in the epoch prior to galaxy formation and have compared these with the results of searches made so far.

This review highlights some of the cosmological theories proposed as alternatives to the standard hot big bang model. Specific ideas discussed here are the matter - antimatter symmetric cosmologies, the empirical two-component model, the G-varying cosmologies, the chronometric cosmology and a simplified quantum cosmology. It is argued that many alternative cosmologies have contributed useful concepts and offered observational tests that have enriched the field of cosmology as a science.

Topology of the universe is the remains of quantum cosmology. The theoretical and observational aspects for the topology of the universe are discussed to show that the significances of topology of the universe in present observations can shed some light on the properties of the universe in the quantum cosmological era.

Extragalactic astronomy rests on the assumption that red-shifts are always equal to velocities and that large velocities are unambiguous distance indicators. There are now many observations which disprove this fundamental assumption. We here review the evidence which has been accumulating for 20 years with particular emphasis on the most recent developments.

Three statistical tests applied to 65 UV excess objects in the field of NGC 520 lead to no detection of any significant alignment.

We study the existence of missing mass in the outermost regions of galaxies not accessible to study by rotation curve methods. We consider binary galaxies, groups and clusters of galaxies. Arp has previously explained redshift asymmetries in pairs or groups with “non-Doppler redshifts”. Instead, we propose the asymmetries indicate contamination by optical pairs or by members which are not gravitationally bound to the group or pair. The group samples which are commonly used to justify very high missing mass values in spiral galaxies (>> the mass detected by rotation curves) also exhibit significant redshift asymmetries. From this and other information, we conclude that spiral galaxies do not possess very massive halos. Only the rare giant elliptical galaxies, such as the binary pair in the center of the Coma Cluster of galaxies, apparently possess extremely massive halos. Dynamical effects of such giants lead to overestimates of the mass of clusters. The evidence indicates that missing mass sufficient to close the universe is not concentrated in individual galaxies, groups or rich clusters.

Recent developments in physics and astrophysics lead us to reintroduce a new tired-light mechanism, implying an interaction between a massive photon and the particles of Dirac's vacuum.

Our examination of the absolute luminosities and sizes of ∼500 lenticular and spiral members of several clusters has revealed appreciable differences in the galaxy luminosity-diameter relationships for different clusters.

Angular separation-magnitude plots drawn from deep photometry of galaxies in distant clusters show evidence for luminosity segregation which cannot be accounted for by field contamination. This segregation, interpreted in terms of dynamical friction, allows one to determine (M/L)g, the mass-to-light ratio of galaxies from their velocity dispersion. In A370 (z=0.37) more than 30 velocities have been measured by multi-aperture spectroscopy, leading to (M/L)g ∼70. Values greater than 100 are found in 5 other distant clusters by deriving the velocity dispersion from the richness. The luminosity segregation, observed even inside each of the clumps of 3C299, could result either from dynamical friction inside the clumps or from some early environmental influence.

Temperatures and iron abundances in two distinct regions of the Perseus Cluster, based on X-ray observations made with SPARTAN 1, are reported. Iron abundance values relative to solar are and , and the temperatures are and for the regions 0′ to 5′ and 6′ to 20′ from the cluster center, respectively. The uncertainties are 90% confidence.

Excess optical and radio emission in nuclei of Seyfert galaxies and quasars is observationally related to nearby companions. Dahari found Seyferts are more strongly perturbed tidally by companions than normal spirals are. QSO data suggests a similar relationship. Quasar and Seyfert activity are thought to be fueled by gas inflow to the nucleus. To study whether gravitational tides from companions cause inflow from the spiral's disk, we use a self-gravitating 60,000 particle disk in Miller's polar n-body program. The perturbation to produce levels of inflow required for activity matches Dahari's Seyfert triggering level. QSO's are also perturbed by observed companions more than necessary for high inflow. We reanalyze Dahari's data to find that at least the majority of Seyferts are in multiple systems. Tidal triggering thus could be the main cause of Seyfert activity.

A pair of emission-line galaxies with separation 7.1 arcseconds was found from the survey of the UK Schmidt objective-prizm plates. The spectroscopic observations by the 1.88m reflector of the Okayama Observatory show the same emission-line features with Z=0.0441.

The study on the Seyfert environment has been of considerable interest lately, since it is believed that the tidal force of a close companian may drive gas into the inner region and either fuel nuclear activity directly or lead to starbursts (Toomre et al., 1972, Byrd, 1987). Many authors noticed an excess of Seyfert among close pairs of galaxies (Adams, 1977, Kennicutt et al., 1984, Keel et al., 1984, Dahari, 1984, 1985 a, b). In a recent paper of ours (Chen and Zou, 1986), a neighborhood statistical study has been done for the galaxies in CfA sample (Huchra et al., 1983), and it is found that the fraction of Seyferts is 3 times higher than the average one, if the distances between them and its nearest neighbors are less than 20 kpc. The result would strengthen the opinion that the existance of close companian is a favourable environment to trigger Seyfert activities.

Recent VLBI observations of the central radio components in the lobe-dominated radio galaxies 3C111 (Götz et al. 1987) and 3C390.3 (Alef et al. 1987) show drastic changes in the structure of the compact emission regions. In 3C111 a jet-like feature with two knots and a flux density of 600 mJy which was visible in 1980.4 had disappeared in 1985.4. This implies “superluminal behaviour” with a characteristic speed of ≳ 3c. In 3C390.3, there is also evidence for superluminal motion: radio knots appear to be ejected from the core at a rate of about one every 4 years and move out with an apparent velocity of 4.1 c (Ho = 50 km/s/Mpc throughout this paper) in the direction of the north-west extended lobe.

Radio source counts at several wavelengths are shown and discussed in terms of evolving populations. The deepest counts now reach a surface density close to a million sources per steradian. At this level essentially all of the luminous radio galaxies and quasars appear to be included, and the weaker sources apparently reflect a relatively nearby population of less luminous radio sources.

Using 45-m radio-telescope at NRO, we obtained log N - log S curves at 10 GHz for flat- and steep-spectrum sources separately. A simple model-fitting of evolution is given.