Working Papers Astronomy and Astrophysics Panel Reports (1991) / Chapter Skim
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Theory and Laboratory Astrophysics
Theory and Laboratory Astrophysics
Pages 177-198
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From page 177... ...
. Agency Responses to Field Committee Report Policy Recommendations for the 90's: Theory Policy Recommendations for the 90's: Laboratory Astrophysics VI.
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From page 178... ...
Observations are yielding new pieces to the puzzle, advances in computer hardware and algorithms are improving our ability to explore how the pieces of the puzzle might fit together, and new ideas from particle physics are offering a variety of world pictures that the pieces might fit into. The feeling
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From page 179... ...
The deep galaxy redshift surveys in progress and planned will contain the information from which direct and statistical measures of the large-scale galaxy space distribution and peculiar velocity field can lee derived. It will be a fascinating task to devise ways to extract this information and learn how to compare this information to the large-scale fluctuations in the galaxy space distribution, and to compare these fluctuations to those predicted by theoretical models.
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From page 180... ...
It is possible that the 90's may see the theoretical subject of galactic structure largely subsumed within cosmology. Star Formation and the Interstellar Medium The problem of star formation is central to a broad variety of problems in galactic astronomy and cosmology.
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From page 181... ...
The relativistic component of the ISM, the cosmic rays, has an important effect on the dynamics of the interstellar medium as well as on the ionization and thermal equilibrium of interstellar gas. The coming decade should see important advances in our understanding of the acceleration and propagation of the cosmic rays, driven in part by measurements of the cosmic ray composition and of the gamma ray emission associated with cosmic rays.
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From page 182... ...
All of these terminations are challenging problems with importance for the chemical evolution of the Galaxy. High-Energy Astrophysics A significant portion of the energetic radiation in the Universe is believed to originate from the accretion of matter onto collapsed objects—neutron stars, stellar black holes, and massive black holes in galactic nuclei.
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From page 183... ...
There is a still greater need for a deeper understanding of atomic, molecular and optical physics so that those processes that are relevant to the interpretation and guidance of the observations are identified, subjected to laboratory investigations, and incorporated into astronomical theories. Quantitative analyses of the spectra of astronomical sources and of the processes that populate the atomic and molecular energy levels that give rise to emission and absorption require accurate data on transition frequencies, oscillator strengths, transition probabilities, electron impact excitation, deactivation and ionization cross sections, photoionization and photodetachment cross sections, radiative and dielectronic recombination and radiative attachment rate coefficients, and cross sections for heavy particle collisions in
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From page 184... ...
Likely developments include: utilization of new techniques to measure important reaction cross sections, the measurement of key reactions in inhomogeneous big bang models, and direct and indirect measurements of reactions involving radioactive nuclei important for understanding explosive burning. While there is strong interest from the nuclear physics community in astrophysical problems, there is a clear change of direction in nuclear physics that is likely to have an important impact on nuclear astrophysics.
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From page 185... ...
NASA's support for theory, already strong, should grow with the increase in the science portion of the astrophysics budget. DOE should support theoretical astrophysics at universities and DOE laboratories insofar as it is relevant to its mission.
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From page 186... ...
We note that the separate theory program in the Physics Division of NSF has been highly successful. In order for the theory program in the Astronomy Division to be equally successful, it must be adequately funded: a level of at least 15% of the university grants program would begin to approach that in the Physics Division, and would be consistent with the recommendation of the Field Committee (which was never implemented)
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From page 187... ...
|NASA ASTROPHYSICS THEORY GRANTS 8 1 ' ' ~. ~— ~ , , I I I / I I I 1 1 1 ~ 1 1 1 1 1 I I I / I I I , ~~ · - ~ F l l l l l l l l 1 1 1 1 1 1 1 1 C 0.15 ~= 1 1 1 1 1 1 1 l I , I I I I I 1 ~ 1 1 1 N l l l l l l l l 1 1 1 1 1 1 1 l l l l l l l l l l l l l 1 1 1 ~ 1 1 1 1 0.00- i i ~ I I I ~ I 87 88 89 90 91 92 93 94 95 FISCALYEAR | Fraction of [R&A Theory]
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From page 188... ...
3. NASA should continue to support theoretical astrophysics at the Space Telescope Science Institute and at NASA Centers such as Ames and Goddard.
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From page 189... ...
This is already done in particle physics at LBL in a way that is compatible with astrophysics needs. Similarly, the Kellogg Lab at Caltech has carried out this function to date in nuclear astrophysics, but it is unclear
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From page 190... ...
In the last decade, debate raged as to the pervasiveness of the hot component of the ISM and on the relative importance of magnetic fields in determining the observed structure of the ISM. The discovery of small dust grains and polycyclic aromatic hydrocarbons through infrared observations led to extensive theoretical study
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From page 191... ...
It was suggested that this dissipation is accomplished through a magnetically driven wind, thereby producing the bipolar flows which are a ubiquitous feature of low-mass star formation. The magnetic field is an essential ingredient in this entire picture, and models of magnetically supported clouds received striking confirmation at the end of the decade when direct observations of the magnetic field in molecular clouds showed approximate equipartition between the magnetic energy and the turbulent energy over a range of densities.
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From page 192... ...
Of particular importance have been the verification of predictions of standard homogenous Big Bang Nucleosynthesis (BBN)
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From page 193... ...
The physics of baryon non-conservation in the GUT theories gave the first models for the origin of the excess of matter over antimatter and for the ratio of baryons to photons in the Universe. Phase transitions predicted from particle physics played a role in the study of a variety of effects from magnetic monopoles to seeds for galaxy formation, to inhomogeneous Big Bang Nucleosynthesis.
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From page 194... ...
New information on nuclear cross sections has contributed to our understanding of solar neutrino production and big bang nucleosynthesis, along with steltar evolution and nucleosynthesis. New measurements of fundamental particle properties have also provided key input to our astrophysical understanding.
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From page 195... ...
The fraction of the NSF astronomy budget going into Theory is about 1/3 the fraction going into Theory in NSF Physics. Despite the recommendation of the Theory subpanel that Theoretical Astrophysics be set up as a separate program in the Astronomy Division, similar to Theoretical Physics in the Physics Division, theory remains balkanized among different programs, to the perceived detriment of researchers who are oriented towards general physical processes rather than towards specific astronomical objects.
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From page 196... ...
* DOE should support theoretical astrophysics insofar as it is relevant to its mission.
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From page 197... ...
Laboratory astrophysics requires new funds, particularly from NSF and NASA, in order to obtain the data that is essential for the interpretation of astronomical observations. The successes of the 1980's and the opportunities for the 1990's show that support for these programs is necessary if astronomy is to achieve its goals in the coming decade.
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From page 198... ...
CANFIELD, University of Hawaii EDWARD L CHUPP, University of New Hampshire DRAKE DEMING, NASA Goddard Space Flight Center GEORGE A
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