Darwin curves and galaxy arms

In the natural world, there exists one kind of structure which is beyond the scope of human laboratorial experiment. It is the structure of galaxies which is usually composed of billions of stars. Spiral galaxies are flat disk-shaped. There are two types of spiral galaxies. The spiral galaxies with some bar-shaped pattern are called barred spirals, and the ones without the pattern are called ordinary spirals. Longer-wavelength galaxy images (infrared, for example) show that ordinary spiral galaxies are basically an axi-symmetric disk that is called exponential disk. For a planar distribution of matter, Jin He defined Darwin curves in the plane as such that the ratio of the matter densities at both sides of the curve is constant along the curve. Therefore, the arms of ordinary spiral galaxies are Darwin curves. Now an important question is that: Are the arms of barred spiral galaxies the Darwin curves too? Fortunately, Jin He designed a piece of Galaxy Anatomy graphic software. With the software, not only can people simulate the stellar density distribution of barred spiral galaxies but also can draw the Darwin curves of the simulated galaxy structure. This paper shows partial evidence that the arms of galaxy NGC 3275, 4548 and 5921 follow Darwin curves.     

Newtonian Gravity Reformulated

With reference to MOND we propose a reformulation of Newton’s theory of gravity in the sense of the static electrodynamics introducing a “material” quantity in analogy to the dielectric “constant”. We propose that this quantity is induced by vacuum polarizations generated by the gravitational field itself. Herewith the flat rotation curves of the spiral galaxies can be explained as well as the observed high velocities near the center of the galaxy should be reconsidered.     

Radio emission from interstellar neutral hydrogen

The emission line for neutral hydrogen at 1420 Mc/s is the only line so far discovered in radioastronomy. Since its mechanism of origin is completely understood, observations of this line provide direct information about conditions in interstellar space such as temperatures, densities and velocities. Extensive investigations of our own Milky Way system have shown clearly that it is a spiral galaxy similar to, but rather smaller than, the great spiral nebula in Andromeda. Our knowledge of the spiral structure of galaxies is far from complete; hydrogen-line measures of high-speed expansions in the centre of the Milky Way system may provide a clue to the understanding of this problem. In addition, determinations of the hydrogen content of different types of galaxy reinforce current theories which suggest that irregular galaxies evolve through the spiral form to elliptical galaxies.     

Is Galaxy Dark Matter a Property of Spacetime?

We describe the motion of a particle in acentral field in an expanding universe. Use is made ofa double expansion in 1/c and 1/, where c and are the speed of light and the Hubble time. In thelowest approximation the rotational velocity is shownto satisfy v⁴ = 2/3 GMcH₀, whereG is Newton's gravitational constant, M is the mass ofthe central body (galaxy), and H₀ is theHubble constant. This formula satisfies observations of stars moving inspiral and elliptical galaxies, and is in accordancewith the familiar Tully–Fisher law.     

Gravitational lensing by spiral galaxies

Spiral galaxies at moderate redshifts and oriented optimally could form characteristic multiple images of extended background sources from which the mass distribution in the galaxy can be estimated. The absorption profile due to the galaxy provides a reliable tool for the chemical and thermal diagnostic of the lens.     

Hubble Space Telescope observations of distant galaxies

The study of faint galaxies has inspired cosmologists since Edwin Bubble's pioneering observations in the 1920s. Appropriately, the successfully refurbished Space Telescope named after Hubble now holds the key to unravelling many of the outstanding questions in modern extragalactic astronomy, including how galaxies form and evolve in the expanding cosmos. The combination of Hubble Space Telescope's exquisite imaging and spectroscopy from ground-based telescopes is being used to resolve a major puzzle concerning a population of low mass galaxies which was particularly abundant a few billion years ago but which has mysteriously vanished by the present epoch. The solution to the puzzle may shed new light on the physical processes which produce the rich variety of galaxy types we see today.     

Theory of Gravitational-Inertial Field of Universe

In this paper the basic proposition is a generalization of the metric tensor by introduction of an inertial field tensor satisfying ?_ig_lm ? g_lm;i ≠ 0. On the basis of variational equations a system of more general covariant equations of gravitational-inertial field is obtained. In Einstein's approximation these equations reduce to the field equations of Einstein. The solution of fundamental problems of generl taheory of relativity by means of the new equations give the same results as Einstein's equations. However application of these equations to the cosmologic problem leads to following results: 1. All Galaxies in the Universe (actually all bodies if gravitational attraction is not considered) “disperse” from each other according to Hubble's law. Thus contrary to Friedmann's theory (according to which the “expansion of Universe” began from the singular state with an infinite velocity) the velocity of “dispersion” of bodies begins from the zero value and in the limit tends to the velocity of light. 2. The “dispertion” of bodies represents a free motion in the inertial field and Hubble's law represents a law of motion of free bodies in the inertial field - the law of inertia. All critical systems (with Schwarzschild radius) are specific because they exist in maximal inertial and gravitational potentials. The Universe represents a critical system, it exists under the Schwarzschild radius. In the high-potential inertial and gravitational fields the material mass in a static state or in the process of motion with decelleration is subject to an inertial and gravitational “annihilation”. Under the maximal value of inertial and gravitational potentials (= c²) the material mass is completely “evaporated” transforming into a radiation mass. The latter is concentrated in the “horizon” of the critical system. All critical systems –“black holes”- represent geon systems, i.e., the local formations of gravitational-electromagnetic radiations, held together by their own gravitational and inertial fields. The Universe, being a critical system, is “wrapped” in a geon crown. The Universe is in a state of dynamical equilibrium. Near the external part of its boundary surface a transformation of matter into electromagnetic-gravitational-neutrineal energy (geon mass) takes place. Inside the Universe, in the galaxies takes place the synthesis of matter from geon mass, penetrating from the external part of the world (from geon crown) by means of a tunneling mechanism. The geon system may be considered as a natural entire cybernetic system.     

Why are spherical stellar systems relaxed?

Spherical stellar systems, from globular star dusters to compact galaxy clusters, appear to be dynamically relaxed. In galaxies and galaxy clusters, collisional relaxation acts too slowly to produce the observed result; and a new argument suggests that the same may be true of globular star clusters. Violent relaxation requires special initial conditions and seems unable to produce sufficiently extended halos. It is here proposed that dynamical relaxation may result from tidal perturbations by external systems. If this explanation is correct, it has important implications for the early history of galaxies and galaxy clusters.This essay was awarded the fourth prize for 1976 by the Gravity Research Foundation.     

DYNAMIC ANALYSIS OF A SPIRAL BEVEL-GEARED ROTOR-BEARING SYSTEM

Spiral bevel gears can transmit motion between two rotors, which are commonly perpendicular to each other. In this paper, the dynamic analysis of a spiral bevel-geared rotor-bearing system is studied. Firstly, the constraint equation describing the relationship between the generalized displacements of spiral bevel gear pairs is derived briefly. Then the modelling of coupled axial-lateral-torsional vibration of the rotor system geared by spiral bevel gears is discussed. Finally, the mechanism of coupled vibration of the spiral bevel-geared rotor system is analyzed theoretically and the dynamic behavior of the system is investigated numerically. The conclusions are characterized as follows. The influences of the critical speeds in rigid journal supports, stability threshold speed and unbalanced responses in hydrodynamic journal bearings are not remarkable in comparison with the spur bevel-geared system under the same conditions. However, the critical speeds and stability threshold speed are essentially affected by boundary conditions such as the torsional stiffness, and meanwhile the effect of the unbalanced responses is not prominent under the concerned rotating speeds except that around the resonance peaks. The steady state response due to torsional excitation is also analyzed, and the results show that it cannot be neglected either in the torsional direction or in the lateral and axial directions in the spiral bevel-geared rotor system.     

The Carmeli Metric Correctly Describes Spiral Galaxy Rotation Curves

The metric by Carmeli accurately produces the Tully-Fisher type relation in spiral galaxies, a relation showing the fourth power of the rotation speed proportional to the mass of the galaxy. And therefore it is claimed that it is also no longer necessary to invoke dark matter to explain the anomalous dynamics in the arms of spiral galaxies. An analysis is presented here showing Carmeli’s 5 dimensional space-time-velocity metric can also indeed describe the rotation curves of spiral galaxies based on the properties of the metric alone.     

Dynamic Equations for Tachyon Gas

Dynamics of the tachyon gas is considered. It is interesting in the relation, that dark matter phenomenon is explained freely by existence of the tachyon gas. Tachyons have two unexpected properties: (1) a single tachyon cannot be detected and (2) the tachyon gas can be detected by its gravitational field. Although molecules (tachyons) of the tachyon gas moves with superluninal velocities, the mean motion of these molecules appears to be less, than the speed of the light. The tachyon gas properties differs from those of usual gas. The pressure of the tachyon gas is very high. It is not isotropic and depends on the gravitational potential. As a result the tachyon gas may form huge halos around galaxies. These halos have very large and almost constant density. This circumstance can explain the law of star velocities at the periphery of a galaxy. Properties of the tachyon gas admit one to consider it as a dark matter.     

Dark energy in systems of galaxies

The precise observational data of the Hubble Space Telescope have been used to study nearby galaxy systems. The main result is the detection of dark energy in groups, clusters, and flows of galaxies on a spatial scale of about 1–10 Mpc. The local density of dark energy in these systems, which is determined by various methods, is close to the global value or even coincides with it. A theoretical model of the nearby Universe has been constructed, which describes the Local Group of galaxies with the flow of dwarf galaxies receding from this system. The key physical parameter of the group-flow system is zero gravity radius, which is the distance at which the gravity of dark matter is compensated by dark-energy antigravity. The model predicts the existence of local regions of space where Einstein antigravity is stronger than Newton gravity. Six such regions have been revealed in the data of the Hubble space telescope. The nearest of these regions is at a distance of 1–3 Mpc from the center of the Milky Way. Antigravity in this region is several times stronger than gravity. Quasiregular flows of receding galaxies, which are accelerated by the dark-energy antigravity, exist in these regions. The model of the nearby Universe at the scale of groups of galaxies (～1 Mpc) can be extended to the scale of clusters (～10 Mpc). The systems of galaxies with accelerated receding flows constitute a new and probably widespread class of metagalactic populations. Strong dynamic effects of local dark energy constitute the main characteristic feature of these systems.     

Fractional Action Cosmology: Emergent,Logamediate, Intermediate,Power Law Scenarios of the Universe and Generalized Second Law of Thermodynamics

In the framework of Fractional Action Cosmology (FAC), we study the generalized second law of thermodynamics for the Friedmann Universe enclosed by a boundary. We use the four well-known cosmic horizons as boundaries namely, apparent horizon, future event horizon, Hubble horizon and particle horizon. We construct the generalized second law (GSL) using and without using the first law of thermodynamics. To check the validity of GSL, we express the law in the form of four different scale factors namely emergent, logamediate, intermediate and power law. For Hubble, apparent and particle horizons, the GSL holds for emergent and logamediate expansions of the universe when we apply with and without using first law. For intermediate scenario, the GSL is valid for Hubble, apparent, particle horizons when we apply with and without first law. Also for intermediate scenario, the GSL is valid for event horizon when we apply first law but it breaks down without using first law. But for power law expansion, the GSL may be valid for some cases and breaks down otherwise.     

The Persistent Problem of Spiral Galaxies

The current explanation for spiral galaxies is that density waves in a spiral form rotate through the disks of these galaxies, continually forming new arms of hot bright stars and excited gas. The discussion here shows that many observed properties of spiral galaxies contradict this assumed density wave mechanism. Alternatively, it has been clear since the early 1950's that galaxies characteristically eject material from their nuclei. A number of astronomers have presented evidence that it is those ejections from the central regions of rotating galaxies that are responsible for the spiral arms. The evidence is reviewed and evaluated here, and it is concluded that the form and nature of the arms, their magnetic fields and rotational velocity characteristics, can best be explained by ejections of material, including plasma, from which the spiral arm stars are formed. This conclusion furnishes an answer to the long-standing problem of how the magnetic fields arise in the outer regions of spirals. Perhaps most importantly, the formation and renewal of spiral arms by ejection of plasma does not require them to be in rotation only under the pull of gravitational forces. If rotational energy is transferred to outer regions by ejections, the current interpretation of rotation curves may overestimate masses of spiral galaxies. If the problem of "missing mass" is diminished, so is the necessity for exotic suggestions to account for this undetected matter.     

A geometric aspect of Hubble's phenomenon

The conventional interpretation of the Hubble effect as a Doppler effect, based upon the concept of an expanding universe or based upon the idea of a continuously increasing radius of curvature of space, leads to some difficulties. It seems possible to avoid these difficulties by ascribing the redshift of light coming from remote galaxies to the fact that the non-Euclidean structure of the universe gets more and more important as observation extends to regions extremely distant from the point of observation. Hubble's phenomenon thus seems based upon the structure of space and time as judged from the point of observation; this means that it appears as a consequence of the “geometria intrinsica” of the universe.     

Quasi-bound states of a charged particle in a Quantum Well under an applied longitudinal electric field: a simple model calculation

A simple scheme based on the iteration matrix formalism is presented for calculating the quasi-bound states of a charged particle in a Quantum Well in the presence of an applied electric field perpendicular to the well. The present approach avoids complicated boundary value problems usually encountered in computing the bound eigenvalues of the one-dimensional Schrodinger equation in the presence of a linear potential. A “low-field” approximation is made in order to derive simple analytic expressions: the consequencies of such approximation are investigated through the comparison with numerical results. As simple application, the resonant-tunneling transmission probability through a double-barrier structure is computed.     

Novel test of modified Newtonian dynamics with gas rich galaxies

The current cosmological paradigm, the cold dark matter model with a cosmological constant, requires that the mass-energy of the Universe be dominated by invisible components: dark matter and dark energy. An alternative to these dark components is that the law of gravity be modified on the relevant scales. A test of these ideas is provided by the baryonic Tully-Fisher relation (BTFR), an empirical relation between the observed mass of a galaxy and its rotation velocity. Here, I report a test using gas rich galaxies for which both axes of the BTFR can be measured independently of the theories being tested and without the systematic uncertainty in stellar mass that affects the same test with star dominated spirals. The data fall precisely where predicted a?priori by the modified Newtonian dynamics. The scatter in the BTFR is attributable entirely to observational uncertainty, consistent with a single effective force law.     

Numerical solution of momentum balance equations for plasmas with two ion species

In plasmas bounded by material surfaces the Bohm criterion has to be satisfied at the entrance of the Debye sheath near the surface. With a single ion species this constraint prescribes a boundary condition for the momentum balance equation governing the ion mass velocity. If, however, several ion species are present a generalization of the Bohm criterion does not provide enough number of boundary conditions. Additional “intermediate” conditions follow from the requirement that spatial derivatives of the ion velocities are finite everywhere within the plasma volume. The amount of such independent conditions is sufficient to determine, in an iterative way, also the position in the plasma where they have to be imposed. A numerical approach to find unique regular solutions of fluid motion equations, satisfying the generalized Bohm criterion at the plasma boundary, is elaborated and realized for the case of two ion species.     

Supernovae and cosmology

The extreme luminosity and their fairly unique temporal behaviour have made supernovae a superb tool to measure distances in the universe. As complex astrophysical events they provide interesting insights into explosion physics, explosive nucleosynthesis, hydrodynamics of the explosion and radiation transport. They are an end product of stellar evolution and provide clues to the stellar composition. Since they can be observed at large distances they have become critical probes to further explore astrophysical effects, like dust properties in external galaxies and the star formation history of galaxies. Some of the astrophysics interferes with the cosmological applications of supernovae. The local velocity field, distorted by the gravitational attraction of the local large scale structure, and the reddening law appear at the moment the major limitations in the accuracy with which cosmological parameters can be determined. These absorption effects can introduce a secondary bias into the observations of the distant supernovae, which needs to be carefully evaluated. Supernovae have been used for the measurement of the Hubble constant, i.e. the current expansion rate of the universe, and the accelerated cosmic expansion directly inferred from the apparent faintness of the distant supernovae.