Radio-frequency emission from supernova ejecta

1967 ◽  
Vol 31 ◽  
pp. 429-430
Author(s):  
S. A. Colgate
Keyword(s):  
Background Radiation ◽  
Dominant Role ◽  
Black Body ◽  
Short Wave ◽  
List Type ◽  
Type Number ◽  
Thermal Radio Emission ◽  
Wave Emission ◽  
Stellar Sources ◽  
The Universe

A new mechanism is proposed for non-thermal radio emission, which depends upon the scattering of photons within an unstable counter-streaming plasma. This mechanism may play a dominant role in several phenomena:(i)the short-wave emission from quasi-stellar sources;(ii)the emission from symmetric supernova nebulae in the early stages of the nebular expansion;(iii)maintenance or modification of the 3 °K black-body background radiation of the Universe.

scholarly journals Summary Talk : Multi-Wavelength Sky Surveys

1998 ◽  
Vol 179 ◽  
pp. 493-499
Author(s):  
O. Lahav
Keyword(s):  
Gamma Rays ◽  
Dimensional Space ◽  
Instrument Design ◽  
List Type ◽  
Type Number ◽  
Sky Surveys ◽  
3 Dimensional ◽  
Multi Wavelength ◽  
The Universe ◽  
Summary Talk

An astronomer's career can be viewed in a 3-dimensional space where the (nearly orthogonal) axes are : – the objects of interest (from planets to the Universe),– techniques (from instrument design to analytic calculations),– the wavelength (from the radio to gamma rays).

scholarly journals Interpretation of Cosmological Information on Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 247-257
Author(s):  
G. Burbidge
Keyword(s):  
Radio Astronomy ◽  
Background Radiation ◽  
Radio Galaxies ◽  
Radio Sources ◽  
List Type ◽  
Type Number ◽  
Radio Flux ◽  
Powerful Radio ◽  
Microwave Background ◽  
Microwave Background Radiation

The topic that I have to introduce today is concerned with the question as to whether or not we can obtain any cosmological information from radio astronomy. Alternatively, we may ask “Where does radio astronomy have an impact on cosmology?” There are several areas that must be discussed. They are: 1)The discovery and interpretation of the microwave background radiation.2)The identification of powerful radio sources and the discovery that many of them have large redshifts. If we can prove that the large redshifts mean that the objects are at great distances, then we can use these radio sources as follows:(a)We can attempt to obtain a Hubble relation for the optical objects which are identified with radio galaxies;(b)We can look for a relation between the angular diameters of the radio sources and the redshifts of the optically identified objects and we can also look at relations between the angular diameter and the radio flux;(c)We can construct log N - log S curves and we can carry out luminosity volume tests.

scholarly journals The Microwave Background Radiation: An Alternative View

1992 ◽  
Vol 9 ◽  
pp. 287-289
Author(s):  
Jayant V. Narlikar
Keyword(s):  
Background Radiation ◽  
Big Bang ◽  
Alternative View ◽  
List Type ◽  
Recent Past ◽  
Microwave Background ◽  
Microwave Background Radiation ◽  
Big Bang Model ◽  
The One ◽  
The Universe

Why do we need to think about any alternatives when the primordial interpretation of the microwave background radiation (MBR) has been accepted by so many for so long? The answer is that the primordial interpretation, in spite of its successes has manifest shortcomings in spite of attempts to remove them by so many for so long. To mention a few: a)Why is the MBR temperature 2.7 K? The value is taken as a parameter in all early universe calculations; it is not predicted by the hot big bang theory with or without inflation.b)There are other astrophysical processes of comparable energy density and other radiation backgrounds that have no primordial origin; why should MBR alone stand out as the odd one out just at this epoch?c)Why are there no signatures of structure formation on the MBR; why is it so smooth?d)The hot big bang model relates to the universe in the first three minutes while the MBR is observed in the more recent past; are we not making too long a jump across from the one to the other?

scholarly journals Background Radiation: Probes and Future Tests

1996 ◽  
Vol 168 ◽  
pp. 389-398
Author(s):  
Martin J. Rees
Keyword(s):  
Background Radiation ◽  
Light Element ◽  
Mass Range ◽  
Black Body ◽  
Big Bang ◽  
List Type ◽  
Microwave Background ◽  
Background Spectrum ◽  
Element Abundances ◽  
Microwave Background Radiation

The clearest evidence for the ‘hot big bang’ is of course the microwave background radiation. Its spectrum is now known, from the FIRAS experiment on COBE, to be a very precise black body – indeed, the deviations due to high-z activity, hot intergalactic gas, etc are smaller than many people might have expected. Also the light element abundances have remained concordant with the predictions of big bang nucleosynthesis, thereby giving us confidence in extrapolating back to when the universe was a few seconds old (see Copi, Schramm and Turner 1994 for a recent review). These developments give us grounds for greater confidence in this model than would have been warranted ten years ago. Several things could have happened which would have refuted the picture, but they haven't happened. For instance:(i)Objects could have been found where the helium abundance was far below 23 per cent.(ii)The background spectrum at millimetre wavelengths could have been weaker than a black body with temperature chosen to fit the Rayleigh-Jeans part of the spectrum.(iii)A stable neutrino might have been discovered in the mass range 100eV-1MeV.

Can we use thermodynamics in the systems with gravity?

2017 ◽  
Vol 31 (29) ◽  
pp. 1750272
Author(s):  
A. V. Melkikh ◽  
E. A. Melkikh
Keyword(s):  
Black Hole ◽  
Background Radiation ◽  
Local Equilibrium ◽  
Black Body ◽  
Microwave Background ◽  
Thermodynamical Equilibrium ◽  
Long Range Interactions ◽  
Thermodynamical Parameters ◽  
Microwave Background Radiation ◽  
The Universe

It is shown that the thermodynamical parameters (temperature, pressure, entropy) as well as the concept of “thermodynamical equilibrium”, in general, cannot be introduced for systems with long-range interactions (gravity). Exceptions are dense systems (stars, planets, gas clouds), where the local equilibrium is caused by short-range forces, as well as by the creation and annihilation of photons. Local equilibrium can also be justified for cosmic microwave background radiation. It is shown that, despite the fact that the radiation of a black hole approximately corresponds to the radiation of a black body, it is impossible to introduce entropy and temperature of a black hole. Restrictions for the application of the thermodynamic parameters to the evolution of the universe as a whole are considered.

scholarly journals The Problem of the Redshifts

1983 ◽  
Vol 104 ◽  
pp. 65-71
Author(s):  
Geoffrey Burbidge
Keyword(s):  
Statistical Information ◽  
List Type ◽  
Type Number ◽  
Expansion Of The Universe ◽  
The Universe

It is my intention in this brief paper to present once again some of the evidence which appears to show that a major contribution to the redshifts of QSOs and perhaps some galaxies is not associated with the expansion of the universe. The evidence continues to grow and it is of four kinds: (a)Evidence concerning galaxies with discrepant redshifts.(b)Connections between QSOs and galaxies.(c)Statistical information concerning the association of QSOs with galaxies.(d)Individual and very striking examples of pairings between QSOs and bright galaxies.

J. Howard Sobel on the Kalam Cosmological Argument

2006 ◽  
Vol 36 (4) ◽  
pp. 565-584 ◽  
Author(s):  
William Lane Craig
Keyword(s):  
Ab Initio ◽  
Empirical Evidence ◽  
List Type ◽  
Cosmological Argument ◽  
Type Number ◽  
The Past ◽  
Kalam Cosmological Argument ◽  
Kalām Cosmological Argument ◽  
Physical Cosmology ◽  
The Universe

IntroductionJ. Howard Sobel devotes seventy pages of his wide-ranging analysis of theistic arguments to a critique of the cosmological argument. The focus of that critique falls on the argument a contingentia mundi; but he also offers in passing some criticisms of the argument ab initio mundi, or the kalam cosmological argument.Sobel provides the following Statement of the argument:Everything that begins to exist has a cause of its existence.The universe began to exist.Therefore, the universe has a cause of its existence [that did not begin to exist].Sobel will accept the causal premiss (1) only if ‘begins to exist’ means ‘has a first instant of its existence,’ and he disputes the arguments and evidence for (2).Traditional proponents of the kalam argument sought to justify (2) by means of philosophical arguments against the infinity of the past, while contemporary interest in the argument arises from the empirical evidence of physical cosmology for the truth of (2).

Solar Corona Investigation by the Coronal Line Photometer at Lomnický Peak

1994 ◽  
Vol 144 ◽  
pp. 431-434
Author(s):  
M. Minarovjech ◽  
M. Rybanský
Keyword(s):  
Solar Corona ◽  
Time Resolution ◽  
Active Regions ◽  
High Time ◽  
High Time Resolution ◽  
List Type ◽  
Type Number ◽  
Coronal Line ◽  
Global Cycle

AbstractThis paper deals with a possibility to use the ground-based method of observation in order to solve basic problems connected with the solar corona research. Namely:1.heating of the solar corona2.course of the global cycle in the corona3.rotation of the solar corona and development of active regions.There is stressed a possibility of high-time resolution of the coronal line photometer at Lomnický Peak coronal station, and use of the latter to obtain crucial observations.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

Discussion following the presentation by F. Deubner

1977 ◽  
Vol 36 ◽  
pp. 69-74
Keyword(s):  
List Type ◽  
The Sun ◽  
Type Number ◽  
Harmonic Motion ◽  
Locally Excited ◽  
Long Period ◽  
Coherent Wave ◽  
Short Period ◽  
Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

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