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6 Report of the Panel on Theory, Computation, and Data Exploration
Pages 275-326

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From page 275...
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From page 276...
... The term "data exploration" is introduced to describe the newly emerged discipline of mining insight from large and complex astronomical databases using sophisticated modeling tools. The panel reviews the status of these two branches of astronomy and astrophysics and provides separate sets of recommendations for prioritized initiatives and policy directives.
From page 277...
... No modern observation would make sense, or could be properly interpreted, without the pioneering theoretical work that gave us white dwarfs, neutron stars, black holes, atomic physics, relativity, radiative transfer, hydrodynamics, mechanics, statistical physics, highenergy radiation processes, and so on, and without the theorists who are the developers and users of these concepts and tools. One need only think of Penzias and Wilson without Gamow, Dicke, and Peebles or Bell and Hewish without Gold and Wheeler to understand the centrality of fundamental theory.
From page 278...
... The theory challenges should be planned and budgeted as an integral part of the project or mission. The funds should be allocated through open competition in the national community rather than as addons to observational or instrumentation grants or contracts, and under no circumstances should they divert funds from existing grants programs for broadly based theory.
From page 279...
... The panel envisions the program being administered in much the same way as the successful Hubble postdoctoral program, with postdocs distributed at institutions throughout the country and selected through competitive review. Such a program will provide an indispensable base for fundamental, creative theoretical research; it will identify the most outstanding young theorists and foster their development in a cost-effective way; it can encourage ethnic and gender diversity; and it will enhance the vitality of research at universities across the country and the talent pool available for this research.
From page 280...
... The panel believes that a suitable preliminary guideline is that at least 30 percent of the costs for research personnel in grant programs, academic departments, and research institutes should normally be directed toward theoretical research activity. The most cost-effective mechanism to address the challenge of rightsizing support for theory in this era of discovery is the targeted expansion of existing grants programs at the NSF and NASA that support broadly based theoretical research.
From page 281...
... The NVO will link the major astronomical data assets into an integrated but virtual system that enables a qualitatively new type of astronomical research: automated multiwavelength and multiple-epoch exploration and discovery among all known catalogued astronomical objects. The NVO will initially provide access to tens of terabytes of catalog and image data, growing to multiple petabytes by the end of the decade.
From page 282...
... Details and supporting arguments are found, in each case, elsewhere in this report. P NO PO S E D I N iTiATiVES The panel's principal recommendations take the form of three initiatives in theoretical astrophysics and one in data exploration: · The panel recommends that most prioritized projects or missions recommended by its parent committee, the Astronomy and Astrophysics Survey Committee, be accompanied by one or more coordinated theory challenges.
From page 283...
... Specifically, the panel recommends that at least 30 percent of the support for research personnel in grant programs, academic departments, and research institutes normally should be directed toward theoretical research activities; that major observational facilities, projects, and missions should fund both "harvest" and "seed-corn" theoretical research; and that funding agencies should develop overall guidelines for right-sizing their levels of theory support. A high priority should be given to the expansion of NASA's Astrophysics Theory Program.
From page 284...
... DOE's Defense Programs should recognize more explicitly the close synergy between their national security missions and research in astrophysics and (noting past high returns on investments made, particularly in terms of quality personnel brought into the defense program) should support with programmatic funds certain areas of relevant theoretical research in astrophysics.
From page 285...
... In particular, the 1980s saw the emergence of numerical modeling and simulation as a distinct and powerful subdiscipline of theoretical astrophysics. In a wide variety of astrophysical problems cosmological structure formation, globular-cluster evolution, star formation, supernova explosions, accretion disks and jets, galactic dynamics, formation and evolution of planetary systems the synergy of numerical modeling and analytic theory led to far greater progress than either tool could achieve on its own.
From page 286...
... The panel believes that the importance of the theory leg in astronomy and astrophysics is growing, not only because of the expansion of the scope of theoretical activities to include numerical modeling and data mining, but also because of the increasing sophistication of our conceptual understanding, our rapidly improving numerical algorithms, and the explosion in computer speed and memory. Theory plays several distinct roles in astronomy research: · Theory uses laboratory-tested physical laws to interpret and explain astronomical observations, providing a coherent and satisfying framework for the interpretation of diverse observational data and showing how they fit together to yield an integrated picture of the universe as a whole.
From page 287...
... THEORETjCA~ PARED jCTjONS VERjFjED BY O BSERVATjON Observation has confirmed the following theoretical predictions: · Blackbody spectrum of the cosmic microwave background. The COBE-FIRAS measurement of the spectrum of the cosmic microwave background (CMB)
From page 288...
... The prodigious luminosity of quasars was interpreted almost 30 years ago by theorists to be the accretion of material onto a black hole of mass 106 to 109 times that of the Sun. The inevitable consequence of this dramatic prediction that many inactive nearby galaxies should host massive black holes, even if they are quiet from lack of matter to accrete ("dead quasars")
From page 289...
... Finally, during the past decade theorists have begun to exploit massive data sets to address fundamental issues in astronomy. Some examples of these successes follow: · Magnetobydrodynamic instabilities and accretion disks.
From page 290...
... Detailed numerical simulations of interacting galaxies, made possible by innovations in computer algorithms and the explosive growth of computing power during the past decade, now produce many features in remarkably good accord with those observed in interacting galaxies.
From page 291...
... The development of multiscale algorithms for astrophysical problems, such as tree codes and adaptive mesh refinement, enabled theorists for the first time to resolve a vast range of length scales at reasonable computational cost. · Practical applications of theoretical astrophysics.
From page 292...
... 292 ASTRONOMY AND ASTROPHYSICS IN THE NEW MILLENNIUM: PANEL REPORTS FIGURE 6.2 The distribution of x-ray-emitting hot gas in a cosmological simulation containing both dark matter and ordinary matter. Courtesy of G
From page 293...
... shows that theoretical efforts of the highest quality can be elicited and focused by the conscious and thoughtful intervention of a funding agency. The panel proposes that most new initiatives prioritized by the survey committee should be accompanied by, and continuously interact with, one or more coordinated theory challenges.
From page 294...
... A guideline for the minimum funding required for a worthwhile theory challenge is $2 million. EXAM P YES O F TO SO RY C HAPPEN G ES The specific theory challenges tied to each mission and project should be determined by the informed astronomical community probably through ad hoc panels drawn from the theory community and convened for this purpose.
From page 295...
... Major theory challenges posed by NGST could include the following: · To develop an integrated theory of the formation and evolution of large-scale structure, Lyman-alpha clouds, galaxy clusters, and galaxies. · To understand the formation of planetary systems in the context of star formation and protostellar disks.
From page 296...
... TPF will also allow us to image the centers of our own and nearby galaxies. A possible theory challenge of TPF is to understand the unique objects and processes that occur at the centers of galaxies, such as stellar collisions, tidal disruption of stars, supermassive black holes, accretion discs, and relativistic jets, and to understand how the interplay of these objects leads to the complex phenomena of active galactic nuclei.
From page 297...
... A possible theory challenge for GSMT is to develop models of star and planet formation, concentrating on the long-term, dynamical convolution of disks, infalling interstellar material, and outflowing winds and jets. The modeling of disks, which incorporates both (magnetized)
From page 298...
... A possible theory challenge for the EVLA is to understand from a theoretical perspective the respective roles of star formation and supermassive black holes in powering luminous galactic nuclei. AS ST The Large-Aperture Synoptic Survey Telescope (LSST)
From page 299...
... A possible theory challenge posed by GLAST is to model the relativistic jets that emanate from the central black holes in active galaxies, to elucidate the radiation and acceleration mechanisms in jets. This challenge will require modeling the inner parts of the accretion disk and the "launching" of the jets and explaining particle acceleration within relativistic shocks.
From page 300...
... It will advance our understanding of the dynamo origin of solar magnetic fields and their emergence through the solar surface, the recycling of magnetic flux, the relation of global to small-scale magnetic field organization, and the effect of magnetic fields on convective energy transport and its variation over the solar cycle. A possible theory challenge for AST is to model the solar activity cycle.
From page 301...
... The growth in computing power over the next decade will enable these challenges to be attacked with a far greater level of physical detail and realism than has hitherto been possible. By 2010, it is expected that the national supercomputing centers will provide access to individual systems capable of executing 100 Tflop (10~4 floating point operations per second)
From page 302...
... Such a code would have applications to black hole accretion, relativistic jets, and mergers of neutron stars and black holes. Long time integrations would be possible, permitting the study of topics such as AGN variability and the decay of binary orbits from gravitational radiation.
From page 303...
... , as well as legacy data archives such as the High Energy Astrophysics Science Archive Research Center. The panel recommends the creation of a National Virtual Observatory to accomplish the integration and facilitate the archiving of the nation's priceless astronomical data.
From page 304...
... The astronomer could then use the data mining and cluster analysis tools of the NVO to identify new candidate objects of the same class. SC jENCE RETURN The NVO would enable a wide range of unique and important astronomical research: multiwavelength identification of large candidate samples of objects such as brown dwarfs, high-redshift quasars, gravitational lenses, and ultraluminous infrared galaxies; multiwavelength crossidentification of sources discovered in new surveys and observations; and searches for rare and exotic new objects among the billion or so catalogued sources.
From page 305...
... Expected science returns include the following: · Discovery and identification of unusual astronomical objects. Early examples of this type of science include detection of L and T dwarfs and high-redshift quasars.
From page 306...
... In fact, the panel recommends that one of the first steps toward the NVO should be the establishment of a working group to define the tasks and organizational structure of the NVO more precisely. The NVO would consist of the main repositories of astronomical data in the United States, together with significant computational resources, all connected by high-speed networks.
From page 307...
... · Advanced analysis tools. This layer consists of the advanced visualization, classification, and data mining tools that will be used to exploit NVO data.
From page 308...
... SDSS, and so on are all seen as sources of data that the astronomer needs to access and manipulate in an automated fashion in order to deal efficiently with large numbers (millions) of astronomical objects.
From page 309...
... Took DEVELOPMENT Effective use of the NVO will require the development of basic analysis tools that provide the ability to look at data and perform queries across the different catalogs and to navigate through and manipulate terabyte data sets. Advanced tools will be needed to look at multidimensional objects and discover unexpected patterns in an automated fashion (data mining)
From page 310...
... Documentation, user feedback, and bug-fixing; · Advanced research. Automatic search algorithms, data mining, statistics, and visualization; and · Operations.
From page 311...
... The development cycles for the NVO's four layers (standards, archive services, basic analysis tools, and advanced analysis tools) will go through four phases: (1)
From page 312...
... The level and nature of continued operations for the resulting integrated astronomical data system should be assessed at the end of the 5-year period. NATI O CAL PO 5TD O INTO RAL FE LLOW5 H I P5 IN THEORETICAL A5TROPHY51C5 A strong postdoctoral program is essential for the long-term health of all areas of astronomy and astrophysics.
From page 313...
... These considerations lead the panel to propose a national program of postdoctoral fellowships in theoretical astrophysics tied not to specific missions but rather to elucidating the long-term vision of astrophysical research. The program can be administered in much the same way as the Hubble postdoctoral program; that is, the postdocs will be selected through a competitive peer review and distributed at institutions through313
From page 314...
... RIGHT-51ZING THEORY SUPPORT One of the central issues faced by this panel and by the survey committee is how to determine the appropriate level of support for research in theoretical astrophysics. Prioritizing and budgeting support for theory research faces several challenges: innovative theoretical programs usually cannot promise to achieve a well-defined set of scientific goals within a fixed schedule and budget; when budgets are squeezed or capital projects have cost overruns, theory support is usually the most expendable budget item, and the full impact of theoretical research is often not visible until decades after the research is complete.
From page 315...
... . These arguments lead the panel to the following recommendations: · At least 30 percent of the costs for research personnel in grant programs, academic departments, and research institutes should normally be directed at theoretical research activity.
From page 316...
... in the 1980s was a major shot in the arm for theoretical astrophysics, so that the NSF and NASA programs now provide comparable support for theory. However, despite the best efforts of program officers and administrators at both NSF and NASA, support for theoretical research has not kept pace with the impressive growth in astronomical data over the last 10 years.
From page 317...
... Such expansion would benefit broadly based theoretical research and thus would complement the more directed initiatives of the theory challenge program and the career-development initiative of the national postdoctoral fellowships to establish a balanced and thriving effort in theoretical astrophysics research. Not to address the growing crisis in theory research will jeopardize the future health of both observational astronomy and theoretical astrophysics.
From page 318...
... or to theoretical work in particle physics. · Defense Programs should recognize the close synergy between its national security missions and research in astrophysics and should
From page 319...
... While faculty groups are the norm in many large disciplines of physics, astrophysical theorists are thinly spread among institutions. Conferences allow sharing research results but seldom allow for collaborative work or collective exploration of ideas.
From page 320...
... There are plenty of examples where subfields of astrophysics were given a significant boost by programs such as these; for example, the basic elements of the Cold Dark Matter paradigm for structure formation were substantially worked out during a program at ITP, which is generally acknowledged to have accelerated the development of the subject by at least 2 years. The panel recommends that institutes such as these continue to receive healthy support.
From page 321...
... · Information grids, computational grids. Both the NSF and NASA have programs to link nationally distributed high-value resources such as supercomputers, data archives, and scientific instruments via high-speed networks into what is referred to as a grid.
From page 322...
... AGN active galactic nuclei AIPS+ + Astronomical Image Processing System, software used for image processing and data analysis ALMA Atacama Large Millimeter Array ASCI Accelerated Strategic Computing Initiative (DOE) AST Advanced Solar Telescope ATP Astrophysics Theory Program (NASA)
From page 323...
... . mission ORB gamma-ray burst GSMT Giant Segmented Mirror Telescope, a 30-m-class, ground-based telescope HST Hubble Space Telescope, a 2.4-m-diameter space telescope designed to study visible, ultraviolet, and infrared radiation; the first of NASA's Great Observatories IPAC Infrared Processing and Analysis Center (NASA)
From page 324...
... Rontgen, the discoverer of x rays; a German-U.S.-U.K. collaboration ROTSE Robotic Optical Transient Search Experiment, designed and operated by a collaboration of astrophysicists from the Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of Michigan SDO Solar Dynamics Observatory, a successor to the pathbreaking SOHO mission SDSS Sloan Digital Sky Survey SIM Space Interferometry Mission SIMBAD Set of Identifications, Measurements, and Bibliography for Astronomical Data, created and maintained by the Strasbourg Astronomical Data Center SIRTF Space Infrared Telescope Facility, NASA's fourth Great Observatory, which will study infrared radiation SLAC Stanford Linear Accelerator Center (DOE)
From page 325...
... PANEL ON THEORY, COMPUTATION, AND DATA EXPLORATION TPF Terrestrial Planet Finder, a free-flying infrared interferometer designed to study terrestrial planets around nearby stars VERITAS Very Energetic Radiation Imaging Telescope Array System VLA Very Large Array, a radio interferometer in New Mexico consisting of 27 antennas spread over 35 km and operating with 0.1 arcsec resolution 325


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