scholarly journals Maximally rotating supermassive stars at the onset of collapse: effects of gas pressure

2019 ◽  
Vol 488 (3) ◽  
pp. 4195-4206 ◽  
Author(s):  
Kenneth A Dennison ◽  
Thomas W Baumgarte ◽  
Stuart L Shapiro
Keyword(s):  
Large Range ◽  
Gas Pressure ◽  
The Other ◽  
Dimensionless Parameters ◽  
Linear Approach ◽  
Critical Configuration ◽  
Polar Radius ◽  
Stellar Masses ◽  
The Universe ◽  
Perturbative Treatment

ABSTRACT The ‘direct collapse’ scenario has emerged as a promising evolutionary track for the formation of supermassive black holes early in the Universe. In an idealized version of such a scenario, a uniformly rotating supermassive star spinning at the mass-shedding (Keplerian) limit collapses gravitationally after it reaches a critical configuration. Under the assumption that the gas is dominated by radiation pressure, this critical configuration is characterized by unique values of the dimensionless parameters J/M2 and Rp/M, where J is the angular momentum, Rp the polar radius, and M the mass. Motivated by a previous perturbative treatment, we adopt a fully non-linear approach to evaluate the effects of gas pressure on these dimensionless parameters for a large range of masses. We find that gas pressure has a significant effect on the critical configuration even for stellar masses as large as $M \simeq 10^6 \, \mathrm{M}_{\odot }$. We also calibrate two approximate treatments of the gas pressure perturbation in a comparison with the exact treatment, and find that one commonly used approximation in particular results in increasing deviations from the exact treatment as the mass decreases, and the effects of gas pressure increase. The other approximation, however, proves to be quite robust for all masses $M \gtrsim 10^4 \, \mathrm{M}_{\odot }$.

scholarly journals Investigating the properties of a galaxy group at z = 0.6

2020 ◽  
Vol 15 (S359) ◽  
pp. 188-189
Author(s):  
Daniela Hiromi Okido ◽  
Cristina Furlanetto ◽  
Marina Trevisan ◽  
Mônica Tergolina
Keyword(s):  
Large Scale ◽  
The Other ◽  
Numerical Density ◽  
Spectroscopy Data ◽  
Stellar Kinematics ◽  
Galaxy Groups ◽  
The Galaxy ◽  
The Difference ◽  
The Impact ◽  
The Universe

AbstractGalaxy groups offer an important perspective on how the large-scale structure of the Universe has formed and evolved, being great laboratories to study the impact of the environment on the evolution of galaxies. We aim to investigate the properties of a galaxy group that is gravitationally lensing HELMS18, a submillimeter galaxy at z = 2.39. We obtained multi-object spectroscopy data using Gemini-GMOS to investigate the stellar kinematics of the central galaxies, determine its members and obtain the mass, radius and the numerical density profile of this group. Our final goal is to build a complete description of this galaxy group. In this work we present an analysis of its two central galaxies: one is an active galaxy with z = 0.59852 ± 0.00007, while the other is a passive galaxy with z = 0.6027 ± 0.0002. Furthermore, the difference between the redshifts obtained using emission and absorption lines indicates an outflow of gas with velocity v = 278.0 ± 34.3 km/s relative to the galaxy.

Signature change in p-adic and noncommutative FRW cosmology

2014 ◽  
Vol 29 (27) ◽  
pp. 1450155 ◽  
Author(s):  
Goran S. Djordjevic ◽  
Ljubisa Nesic ◽  
Darko Radovancevic
Keyword(s):  
Loop Quantum Gravity ◽  
Initial Conditions ◽  
Planck Scale ◽  
The Other ◽  
Frw Cosmology ◽  
Signature Change ◽  
Discrete Nature ◽  
Frw Metric ◽  
The Universe ◽  
Friedmann Robertson Walker

The significant matter for the construction of the so-called no-boundary proposal is the assumption of signature transition, which has been a way to deal with the problem of initial conditions of the universe. On the other hand, results of Loop Quantum Gravity indicate that the signature change is related to the discrete nature of space at the Planck scale. Motivated by possibility of non-Archimedean and/or noncommutative structure of space–time at the Planck scale, in this work we consider the classical, p-adic and (spatial) noncommutative form of a cosmological model with Friedmann–Robertson–Walker (FRW) metric coupled with a self-interacting scalar field.

scholarly journals Searching for space-time variation of the fine structure constant using QSO spectra: overview and future prospects

2009 ◽  
Vol 5 (H15) ◽  
pp. 304-304
Author(s):  
J. C. Berengut ◽  
V. A. Dzuba ◽  
V. V. Flambaum ◽  
J. A. King ◽  
M. G. Kozlov ◽  
...  
Keyword(s):  
Nuclear Reactor ◽  
Structure Constant ◽  
Big Bang ◽  
The Other ◽  
Fine Structure Constant ◽  
Spatial And Temporal Variation ◽  
Fundamental Constants ◽  
Future Prospects ◽  
Big Bang Nucleosynthesis ◽  
The Universe

Current theories that seek to unify gravity with the other fundamental interactions suggest that spatial and temporal variation of fundamental constants is a possibility, or even a necessity, in an expanding Universe. Several studies have tried to probe the values of constants at earlier stages in the evolution of the Universe, using tools such as big-bang nucleosynthesis, the Oklo natural nuclear reactor, quasar absorption spectra, and atomic clocks (see, e.g. Flambaum & Berengut (2009)).

Devotional Emerson

2015 ◽  
Vol 22 (1) ◽  
Author(s):  
Jennifer Gurley
Keyword(s):  
The Other ◽  
Modes Of Action ◽  
The World ◽  
The Universe

AbstractAgainst anti-realist readings of the Emersonian self, perhaps most influentially Cavell’s reading, this essay argues that Emerson is a devotional writer. Emerson’s notion of subjectivity is based in two complementary modes of action - one receptive and the other expressive - as one works to “align” oneself with the larger forces that constitute and order the universe. How the world is and how we humans make our way through it are not the same and must not be confused. Such confusion is the decisive mistake the anti-realist critic of Emerson makes. The Emersonian subject must experience the laws of reality directly, on one’s own, rather than “secondhand.” Emerson is a dramatist telling the story of how we come to ideas and learn to judge and to act: of how, that is, we come to have experience. Emerson seeks an unshifting ground through a moment of receptivity and a moment of activity. That he often rarely achieves insight does not make him an anti-realist. This essay demonstrates how, by showing - albeit briefly - that Emersonian experience is fundamentally religious: a work of devotion rather than aversion.

The Measure of All Things

2018 ◽  
Vol 48 (4) ◽  
pp. 403-440 ◽  
Author(s):  
Jérôme Lamy
Keyword(s):  
United States ◽  
Global Warming ◽  
Large Range ◽  
The United States ◽  
Significant Rise ◽  
The Other ◽  
Satellite Mission ◽  
Sea Levels ◽  
Joint Mission ◽  
The 1960S

The TOPEX/POSEIDON satellite mission to observe the oceans triggered the formation of the new specialty of space oceanography from the 1970s to 1990s. Previously, in the 1960s in the United States, traditional oceanographers had shown little interest in the possibilities of space and thus space engineers and physicists worked on the first missions (Seasat in particular). TOPEX/POSEIDON brought together two projects, one American (TOPEX) and the other French (POSEIDON). The gradual crystallization of the disciplinary specialty of space oceanography occurred by making available a platform of instruments able to meet an ensemble of varied needs. Battery failures just before the launch of the joint mission meant that the mission had to focus on the essentials (notably El Niño effects). Subsequently, the discovery of a significant rise in sea levels due to global warming resulted in space oceanography becoming a recognized specialty. The case of TOPEX/POSEIDON shows the original ways in which instruments gained a place in the very large range of oceanographic techniques.

scholarly journals The Theory of the Large Scale Structure of the Universe

1978 ◽  
Vol 79 ◽  
pp. 409-421 ◽  
Author(s):  
Ya B. Zeldovich
Keyword(s):  
Early Childhood ◽  
Sigmund Freud ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
The Other ◽  
Childhood Experiences ◽  
Other Hand ◽  
The Universe ◽  
Single Statement

The God-father of psychoanalysis Professor Sigmund Freud taught us that the behaviour of adults depends on their early childhood experiences. in the same spirit, the problem of cosmological analysis is to derive the observed present day situation and structure of the Universe from certain plausible assumptions about its early behaviour. Perhaps the most important single statement about the large scale structure is that there is no structure at all on the largest scale − 1000 Mpc and more. On this scale the Universe is rather uniform, structureless and isotropically expanding - just according to the simplified pictures of Einstein-Friedmann……. Humason, Hubble…. Robertson, Walker. On the other hand there is a lot of structure on the scale of 100 or 50 Mpc and less. There are clusters and superclusters of galaxies.

The avant-garde’s visual arts in the context of Santayana’s idea of vital liberty

Human Affairs ◽  
2012 ◽  
Vol 22 (2) ◽  
Author(s):  
Krzysztof Skowroński
Keyword(s):  
Twentieth Century ◽  
Visual Arts ◽  
The Other ◽  
Political Life ◽  
The Political ◽  
Human Beings ◽  
Political Dimension ◽  
Avant Garde ◽  
Other Hand ◽  
The Universe

AbstractIn the present paper, the author looks at the political dimension of some trends in the visual arts within twentieth-century avant-garde groups (cubism, expressionism, fauvism, Dada, abstractionism, surrealism) through George Santayana’s idea of vital liberty. Santayana accused the avant-gardists of social and political escapism, and of becoming unintentionally involved in secondary issues. In his view, the emphasis they placed on the medium (or diverse media) and on treating it as an aim in itself, not, as it should be, as a transmitter through which a stimulating relationship with the environment can be had, was accompanied by a focus on fragments of life and on parts of existence, and, on the other hand, by a de facto rejection of ontology and cosmology as being crucial to understanding life and the place of human beings in the universe. The avant-gardists became involved in political life by responding excessively to the events of the time, instead of to the everlasting problems that are the human lot.

Aristotle's Unmoved Movers

Traditio ◽  
1946 ◽  
Vol 4 ◽  
pp. 1-30 ◽  
Author(s):  
Philip Merlan
Keyword(s):  
Middle Ages ◽  
The Other ◽  
World Picture ◽  
The Earth ◽  
Concentric Spheres ◽  
The One ◽  
The Universe ◽  
The Middle Ages

According to Aristotle all heavenly movement is ultimately due to the activity of forty-seven (or fifty-five) ‘unmoved movers'. This doctrine is highly remarkable in itself and has exercised an enormous historical influence. It forms part of a world-picture the outlines of which are as follows. The universe consists of concentric spheres, revolving in circles. The outermost of these bears the fixed stars. The other either bear planets or, insofar as they do not, contribute indirectly to the movements of the latter. Each sphere is moved by the one immediately surrounding it, but also possesses a movement of its own, due to its mover, an unmoved, incorporeal being. (It was these beings which the schoolmen designated as theintelligentiae separatae.) The seemingly irregular movements of the planets are thus viewed as resulting from the combination of regular circular revolutions. The earth does not move and occupies the centre of the universe. Such was Aristotle's astronomic system, essential parts of which were almost universally adopted by the Arabic, Jewish, and Christian philosophers of the Middle Ages.

scholarly journals Universe and Inner Self in Early Indian and Early Greek Thought

2016 ◽  
Keyword(s):  
Economic Development ◽  
The Other ◽  
European Origin ◽  
Greek Thought ◽  
Indian Thought ◽  
Inner Self ◽  
Cosmic Order ◽  
Socio Economic Development ◽  
Close Relationship ◽  
The Universe

This book focuses from various perspectives on the striking similarities (as well as the concomitant differences) between early Greek and early Indian thought. In both cultures there occurred at about the same time the birth of 'philosophy', the idea of the universe as an intelligible order in which personal deity is (at most) marginal and the inner self is at the centre of attention. The similarities include a pentadic structure of narrative and cosmology, a basic conception of cosmic order or harmony, a close relationship between universe and inner self, techniques of soteriological inwardness and self-immortalisation, the selflessness of theory, envisaging the inner self as a chariot, the interiorisation of ritual, and ethicised reincarnation. Explanations for the similarites are a shared Indo-European origin, parallel socio-economic development, and influence in one direction or the other.

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