Interstellar and Intergalactic Medium

2021 ◽  
Author(s):  
Barbara Ryden ◽  
Richard W. Pogge
Keyword(s):  
Intergalactic Medium ◽  
Data Sets ◽  
Clusters Of Galaxies ◽  
Physical Processes ◽  
Molecule Formation ◽  
Order Of Magnitude ◽  
Full Discussion ◽  
Essential Knowledge ◽  
Intracluster Gas ◽  
The Universe

This concise textbook, the first volume in the Ohio State Astrophysics Series, covers all aspects of the interstellar and intergalactic medium for graduate students and advanced undergraduates. This series aims to impart the essential knowledge on a topic that every astrophysics graduate student should know, without going into encyclopedic depth. This text includes a full discussion of the circumgalactic medium, which bridges the space between the interstellar and intergalactic gas, and the hot intracluster gas that fills clusters of galaxies. Its breadth of coverage is innovative, as most current textbooks treat the interstellar medium in isolation. The authors emphasise an order-of-magnitude understanding of the physical processes that heat and cool the low-density gas in the universe, as well as the processes of ionization, recombination, and molecule formation. Problems at the end of each chapter are supplemented by online projects, data sets and other resources.

scholarly journals The Intergalactic Medium

1982 ◽  
Vol 97 ◽  
pp. 453-459
Author(s):  
A. C. Fabian ◽  
A. K. Kembhavi
Keyword(s):  
Radio Emission ◽  
Intergalactic Medium ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intergalactic Gas ◽  
X Ray ◽  
Extended Radio ◽  
X Ray Background ◽  
Ngc 1275 ◽  
Intracluster Gas

The density of intergalactic gas may be an important parameter in the formation of extended radio sources. It may range from ∼ 0.1 particle cm−3 in the centres of some rich clusters of galaxies down to 10−8cm−3 or less in intercluster space. The possible influence of the intracluster gas surrounding NGC 1275 on its radio emission is discussed, and the possibility that a significant fraction of the X-ray background is due to a hot intergalactic medium is explored in some detail.

scholarly journals Superclusters from velocity divergence fields

2020 ◽  
Vol 500 (1) ◽  
pp. L32-L36
Author(s):  
J D Peñaranda-Rivera ◽  
D L Paipa-León ◽  
S D Hernández-Charpak ◽  
J E Forero-Romero
Keyword(s):  
Linear Theory ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Data Sets ◽  
Order Of Magnitude ◽  
Divergence Field ◽  
Divergence Velocity ◽  
Diverse Data ◽  
Autocorrelation Length ◽  
The Universe

ABSTRACT Superclusters are a convenient way to partition and characterize the large-scale structure of the Universe. In this Letter, we explore the advantages of defining superclusters as watershed basins in the divergence velocity field. We apply this definition on diverse data sets generated from linear theory and N-body simulations, with different grid sizes, smoothing scales, and types of tracers. From this framework emerges a linear scaling relation between the average supercluster size and the autocorrelation length in the divergence field, a result that holds for one order of magnitude from 10 up to 100 Mpc h−1. These results suggest that the divergence-based definition provides a robust context to quantitatively compare results across different observational or computational frameworks. Through its connection with linear theory, it can also facilitate the exploration of how supercluster properties depend on cosmological parameters, paving the way to use superclusters as cosmological probes.

Translocations In Space-Time and Simultaneous States of the Universe: Convergent Quantifications and Alternative Solutions from the Principles of Physics for the Challenges of “Time Travel” and “Parallel Universes”

2016 ◽  
pp. 4058-4069
Author(s):  
Michael A Persinger
Keyword(s):  
Single Photon ◽  
Rest Mass ◽  
Space Time ◽  
Hydrogen Line ◽  
Magnetic Forces ◽  
Universal Space ◽  
Potential Applications ◽  
Order Of Magnitude ◽  
Alternative Solutions ◽  
The Universe

                                Translation of four dimensional axes anywhere within the spatial and temporal boundaries of the universe would require quantitative values from convergence between parameters that reflect these limits. The presence of entanglement and volumetric velocities indicates that the initiating energy for displacement and transposition of axes would be within the upper limit of the rest mass of a single photon which is the same order of magnitude as a macroscopic Hamiltonian of the modified Schrödinger wave function. The representative metaphor is that any local 4-D geometry, rather than displaying restricted movement through Minkowskian space, would instead expand to the total universal space-time volume before re-converging into another location where it would be subject to cause-effect. Within this transient context the contributions from the anisotropic features of entropy and the laws of thermodynamics would be minimal.  The central operation of a fundamental unit of 10-20 J, the hydrogen line frequency, and the Bohr orbital time for ground state electrons would be required for the relocalized manifestation. Similar quantified convergence occurs for the ~1012 parallel states within space per Planck’s time which solve for phase-shift increments where Casimir and magnetic forces intersect.  Experimental support for these interpretations and potential applications is considered. The multiple, convergent solutions of basic universal quantities suggest that translations of spatial axes into adjacent spatial states and the transposition of four dimensional configurations any where and any time within the universe may be accessed but would require alternative perspectives and technologies.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

scholarly journals X-ray clusters of galaxies as tracers of structure in the Universe

Nature ◽  
2001 ◽  
Vol 409 (6816) ◽  
pp. 39-45 ◽  
Author(s):  
Stefano Borgani ◽  
Luigi Guzzo
Keyword(s):  
Clusters Of Galaxies ◽  
X Ray ◽  
The Universe

COSMIC ORIGIN OF QUANTIZATION

2004 ◽  
Vol 18 (04n05) ◽  
pp. 519-525 ◽  
Author(s):  
FRANCESCO CALOGERO
Keyword(s):  
Angular Momentum ◽  
Spatial Coherence ◽  
Simplified Model ◽  
Nucleon Mass ◽  
Universal Gravitation ◽  
Large Component ◽  
Missing Mass ◽  
Order Of Magnitude ◽  
The Universe ◽  
Cosmic Origin

An estimate is presented of the angular momentum associated with the stochastic cosmic tremor, which has been hypothesized to be caused by universal gravitation and by the granularity of matter, and to be itself the cause of quantization ("cosmic origin of quantization"). If that universal tremor has the spatial coherence which is instrumental in order that the estimated action associated with it have the order of magnitude of Planck's constant h, then the estimated order of magnitude of the angular momentum associated with it also has the same value. We moreover indicate how these findings (originally based on a simplified model of the Universe, as being made up only of particles having the nucleon mass) are affected (in fact, essentially unaffected) by the possible presence in the mass of the Universe of a large component made up of particles much lighter than nucleons ("dark", or "missing", mass).

scholarly journals Large-Scale Structure in the Universe: Spatial Distribution and Peculiar Velocities

1987 ◽  
Vol 124 ◽  
pp. 335-348
Author(s):  
Neta A. Bahcall
Keyword(s):  
Dark Matter ◽  
Spatial Distribution ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Clusters Of Galaxies ◽  
Large Scale Structures ◽  
Peculiar Velocities ◽  
Scale Structures ◽  
The Universe

The evidence for the existence of very large scale structures, ∼ 100h−1Mpc in size, as derived from the spatial distribution of clusters of galaxies is summarized. Detection of a ∼ 2000 kms−1 elongation in the redshift direction in the distribution of the clusters is also described. Possible causes of the effect are peculiar velocities of clusters on scales of 10–100h−1Mpc and geometrical elongation of superclusters. If the effect is entirely due to the peculiar velocities of clusters, then superclusters have masses of order 1016.5M⊙ and may contain a larger amount of dark matter than previously anticipated.

scholarly journals The fall and rise of consciousness science

2018 ◽  
Author(s):  
Anil Seth
Keyword(s):  
Twentieth Century ◽  
Empirical Study ◽  
Neurological Disorders ◽  
Neural Mechanisms ◽  
Central Feature ◽  
Hard Problem ◽  
Physical Processes ◽  
Wide Range ◽  
Third Person ◽  
The Universe

At the birth of psychology as a science, consciousness was its central problem. But throughout the twentieth century, ideological and methodological concerns pushed the explicit empirical study of consciousness to the sidelines. Since the 1990s, studying consciousness has regained a legitimacy and impetus befitting its status as the central feature of our mental lives. Nowadays consciousness science encompasses a rich interdisciplinary mixture drawing together philosophical, theoretical, computational, experimental, and clinical perspectives. While solving the metaphysically ‘hard’ problem of why consciousness is part of the universe may seem as intractable as ever, scientists have learned a great deal about the neural mechanisms underlying conscious states. Further progress will depend on specifying closer explanatory mappings between (first person subjective) phenomenological descriptions and (third person objective) descriptions of biological and physical processes. Such progress will help reframe our understanding of our place in nature, and may also accelerate clinical approaches to a wide range of psychiatric and neurological disorders.

Extragalactic X-ray sources and the diffuse X-ray background

1979 ◽  
Vol 366 (1726) ◽  
pp. 391-402 ◽  
Keyword(s):  
Spatial Distribution ◽  
Euclidean Space ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Optical Identification ◽  
X Ray ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Order Of Magnitude ◽  
X Ray Background

Results from the Ariel 5 sky survey instrument relating to the properties and the spatial distribution of extragalactic X-ray sources are discussed. The lg N -lg S relation for sources in the 2A catalogue is consistent with a uniform distribution of sources in Euclidean space. In addition, measure­ments of fluctuations in the X-ray background suggest that the Euclidean form of the source counts can be extrapolated to flux levels at least an order of magnitude fainter than the 2A catalogue limit. Information is also available from the optical identification of 2A sources which, through redshift measurements, enables the X-ray luminosity functions of the two main classes of source, namely clusters of galaxies and active galaxies, to be determined. The luminosity functions can be used to calculate the contribution of clusters of galaxies and active galaxies to the diffuse X-ray background in the 2-10 keV range. It is found that cosmological evolution of one or both populations is required to account for the diffuse X-ray background entirely in terms of the integrated emission from these sources.

The Intergalactic Medium

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Structure Formation ◽  
Intergalactic Medium ◽  
Cluster Formation ◽  
Physical Processes ◽  
First Galaxies

This chapter examines the intergalactic medium (IGM). Although much of astronomy focuses on the luminous material inside galaxies, the majority of matter today—and the vast majority at z > 6—actually lies outside these structures, in the IGM. This material ultimately provides the fuel for galaxy and cluster formation and—because it is much less affected by the complex physics of galaxies—offers a cleaner view of the underlying physical processes of structure formation and of fundamental cosmology. The chapter thus takes up the study on the properties of the IGM, especially during the era of the first galaxies (when the IGM underwent major changes).

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