prepublication copy - The Department of Astronomy & Astrophysics ...

More documents

Recommendations

Info

FIGURE 2‐2 The source 3C 75, shown here in x‐rays (blue) and radio waves (pink), is a rare example where two galaxies have been caught in the act of merging. Not only do their stars merge, but their central black holes ‐ each producing a pair of jets containing gas moving outward with speed close to that of light ‐ will do likewise in perhaps a few hundred million years. Many similar mergers involving smaller black holes in the nuclei of younger galaxies are thought to have taken place. When black holes coalesce, they create intense bursts of gravitational radiation. (Credit: X‐ray: NASA/CXC/AIfA/D.Hudson & T.Reiprich et al.; Radio: NRAO/VLA/NRL.) galaxies form and evolve will be possible. We are on the verge of a new era of discovery in gravitational wave astronomy. In addition, gravitational waves could be created by exotic processes occurring in the young universe and would have been propagating freely to us ever since. Several speculative sources such as cosmic strings and abrupt changes in the form that the contents of the universe assumed—“phase changes,” like the change from water to ice—have been suggested but the truth is that we do not quite know what to expect. A possible way to see if there are any measurable signals with wavelengths of roughly light years employs very precise radio measurements of naturally occurring cosmic “clocks” called pulsars. 2 Spread across the sky, the separations between these cosmic clocks will change as a long wavelength gravitational wave passes by, potentially measurably changing the arrival times of their radio pulses. Opening the Time Domain: Making Cosmic Movies By eye, the universe appears static apart from the twinkling of starlight caused by Earth’s atmosphere. In fact, it is a place where dramatic things happen on timescales we can observe—from a tiny fraction of a second to days to centuries. Stars in all stages of life rotate, pulsate, and undergo activity cycles while many flare, accrete, lose mass, and erupt, and some die in violent explosions. Binary neutron stars and black holes merge, emitting, in addition to bursts of radiation, gravity waves. Supermassive black holes in the centers of galaxies swallow mass episodically and erupt in energetic outbursts. Some objects travel rapidly enough for us to measure their motion across the sky. 2 The 1993 Nobel Prize in Physics was awarded to two American astronomers for their work on binary pulsars. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION 2-6
Our targeted studies of variations in brightness and position of different objects indicates that we have only just begun to explore lively variations in the cosmos. If we study the temporal behavior of the sky in systematic ways and over wide ranges of the electromagnetic spectrum, we are sure to discover new and unexpected phenomena. In the highest-energy portion of the electromagnetic spectrum, where the universe shows its greatest variability, the value of viewing large areas of the sky repeatedly on short timescales has been amply demonstrated by the breakthrough capabilities of the Fermi Gamma-ray Space Telescope. The impact of such surveys will be broad and deep, and we give just a few illustrative examples of what the future holds. In our own solar system, new temporal surveys will discover and characterize a vast population of relic objects in the outer reaches of the solar system. These “Kuiper Belt Objects,” of which Pluto is the nearest large example, are the icy residue left over from the formation of our solar system about 4.5 billion years ago. As such, they are the fossil record of events that we can otherwise only theorize about. Moving further away, monitoring the apparent motions of large samples of stars offers a threedimensional view of the structure of the Milky Way that is unobtainable by other means. In this decade, precision space-based measurements with the European mission GAIA will map out the structure of the Milky Way in exquisite detail, enabling us to complete our understanding of the formation of our Galactic neighborhood. Direct geometric measurements of distances to the Galactic Center, to major regions of star formation in the Milky Way, to nearby galaxies, and, most importantly, to galaxies at cosmological distances are possible using precision radio astronomy. Stars can end their lives with dramatic explosions of astounding observational variety. A particular class, Type Ia supernovae, results from the sudden thermonuclear conflagration of a white dwarf (a dense object with the mass of the Sun and the radius of the Earth) and produces a quantifiable amount of visible energy that can be used to map out the geometry of the universe. It remains a theoretical challenge to explain the empirical relation between peak brightness and duration that is used in these critical cosmological studies. Alternatively, supernova explosions of the Type II variety, which are due to the collapse of a single massive star that has exhausted its nuclear fuel, create many of the elements heavier than helium and sometimes produce gamma ray bursts—intense flashes of gamma rays lasting only seconds (Figure 2-3). Again, we do not understand the mechanisms at work. The correct answers are quite likely to surprise us. Time domain surveys of the sensitivity and scope envisioned in the coming decade will increase by orders of magnitude the number and character of stellar explosions that we can study, allowing us to connect variations in the host galaxies and progenitors to the energy and characteristics of the explosions. Supernovae are critical markers both for mapping out the cosmos and for understanding the formation of heavy elements that are found in all of us, so these studies are essential for understanding our origins. By surveying large areas of the sky repeatedly, once every few days, we anticipate the discovery of the wholly unanticipated. Endpoints of stellar evolution we have yet to imagine, and the behavior of ordinary stars outside of our experience, could be discoveries that cause us to dramatically revise our cosmic understanding. Exotic objects and events never before anticipated may be revealed. The full realization of time domain studies is one of the most promising discovery areas of the decade. Advanced gravitational wave detectors will open up a new window on the transient universe, including the last stages of binary neutron star and black hole mergers. Studying electromagnetic counterparts of gravity wave bursts will help illuminate the nature of the sources. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION 2-7
Page 1:
PREPUBLICATION COPY
Page 4 and 5: THE NATIONAL ACADEMIES PRESS 500 Fi
Page 7 and 8: COMMITTEE FOR A DECADAL SURVEY OF A
Page 9 and 10: Panel on Stars and Stellar Evolutio
Page 11 and 12: DOUGLAS FINKBEINER, Harvard Univers
Page 13: SPACE STUDIES BOARD CHARLES F. KENN
Page 16 and 17: activities 2 that have emerged from
Page 18 and 19: In addition to the 27 panel meeting
Page 20 and 21: Acknowledgment of Reviewers This re
Page 22 and 23: The Accelerating Universe 2-26 The
Page 24 and 25: APPENDIXES A Summary of Science Fro
Page 26 and 27: light up the universe, marking the
Page 28 and 29: RECOMMENDED PROGRAM Maintaining a b
Page 30 and 31: TABLE ES.4 Space: Recommended Activ
Page 32 and 33: Cosmic Dawn: Searching for the Firs
Page 34 and 35: this imprint would both probe funda
Page 36 and 37: important outcome will be to open u
Page 38 and 39: estimated to be on the order of $20
Page 40 and 41: observatories. For NASA an annual b
Page 42 and 43: surveys of large fields, enabling s
Page 44 and 45: RECOMMENDATION: U.S. investors in a
Page 46 and 47: departments and the community as a
Page 48 and 49: dominate spending; (2) private-publ
Page 50 and 51: us was certainly evident during the
Page 52 and 53: BOX 2-1 Other Worlds Around Other S
Page 56 and 57: FIGURE 2‐3 Numerical simulation o
Page 58 and 59: FIGURE 2‐4 Left panel: Image of t
Page 60 and 61: FIGURE 2‐6 Top: Schematic of the
Page 62 and 63: Most stars with masses smaller than
Page 64 and 65: BOX 2-2 The Origin of Planets After
Page 66 and 67: send material raining into the cent
Page 68 and 69: BOX 2-4 Lifecycles in Galaxies One
Page 70 and 71: Stars Stars are the most observable
Page 72 and 73: ubiquitous high-energy charged-part
Page 74 and 75: The Nature of Inflation As describe
Page 76 and 77: FIGURE 2‐11 Pie chart showing the
Page 78 and 79: An important clue to the nature of
Page 80 and 81: Studying the properties of neutron
Page 82 and 83: FIGURE 2‐14 A possible pathway is
Page 84 and 85: partners and makes recommendations
Page 86 and 87: As astronomy research has blossomed
Page 88 and 89: are increasingly relevant. The Euro
Page 90 and 91: TABLE 3-1 Currently Operating OIR F
Page 92 and 93: 29% 1990 44% US Priv US Fed Other E
Page 94 and 95: CONCLUSION: Complex and high-cost f
Page 96 and 97: Space Observatories The Laser Inter
Page 98 and 99: Physics Division (PHY); the Mathema
Page 101 and 102: 4 Astronomy in Society Astronomy of
Page 103 and 104: FIGURE 4‐2 The dust sculptures of
Page 105 and 106:
FIGURE 4‐5 President Obama takes
Page 107 and 108:
Astronomy Inspires in the Classroom
Page 109 and 110:
teaching the scientific method. The
Page 111 and 112:
where the fraction of astronomers h
Page 113 and 114:
Percentage of AAS Membership by Fie
Page 115 and 116:
0.4 0.3 0.2 0.1 PL SO IM AG SF IN S
Page 117 and 118:
FIGURE 4‐12 Number (top panel) an
Page 119 and 120:
Professional training needs to acco
Page 121:
assistant and associate professor p
Page 124 and 125:
fluctuating level of funding for as
Page 126 and 127:
THEORY Emerging Trends in Theoretic
Page 128 and 129:
Central to the Galaxies across Cosm
Page 130 and 131:
TABLE 5‐2 Support for astrophysic
Page 132 and 133:
would normally be for a five-year p
Page 134 and 135:
FIGURE 5‐7 Highly cited HST publi
Page 136 and 137:
y optical and radio astronomers are
Page 138 and 139:
FIGURE 5‐8 Number of PhDs per yea
Page 140 and 141:
ated by the Program Prioritization
Page 142 and 143:
nulling interferometry. The appropr
Page 144 and 145:
FIGURE 5‐9 The richness of the su
Page 146 and 147:
RECOMMENDATION: NASA and NSF suppor
Page 148 and 149:
FIGURE 6‐1. All sky map as observ
Page 150 and 151:
FIGURE 6‐3 NASA mission cost over
Page 152 and 153:
FIGURE 6‐5 Gemini North with Sout
Page 154 and 155:
TOWARD FUTURE PROJECTS, MISSIONS, A
Page 156 and 157:
3. Investment in new and upgraded i
Page 158 and 159:
etween several competing elements i
Page 161 and 162:
7 Realizing the Opportunities The p
Page 163 and 164:
FIGURE 7.1 Survey time line showing
Page 165 and 166:
SCIENCE OBJECTIVES FOR THE DECADE T
Page 167 and 168:
Box 7.1 Implementing a Cosmic Dawn
Page 169 and 170:
JWST, with its superb mid-infrared
Page 171 and 172:
optical imaging of brighter galaxie
Page 173 and 174:
Box 7.3 Implementing the Physics of
Page 175 and 176:
FIGURE 7.2 Multiwavelength images o
Page 177 and 178:
Recommendations for New Space Activ
Page 179 and 180:
FIGURE 7.4 Science accomplishments
Page 181 and 182:
significance of mergers in the buil
Page 183 and 184:
independent advice committee review
Page 185 and 186:
committee review. It could range be
Page 187 and 188:
Laboratory Astrophysics As describe
Page 189 and 190:
Recommendations for New Ground-Base
Page 191 and 192:
Program for instrumentation and fac
Page 193 and 194:
excel at high spectral and spatial
Page 195 and 196:
The committee reviewed a technical
Page 197 and 198:
FIGURE 7.10 ACTA would be, like the
Page 199 and 200:
Advanced Technologies and Instrumen
Page 201 and 202:
LISA as soon as possible subject to
Page 203:
FIGURE 7.14 DOE recommended program
Page 207 and 208:
A Summary of Science Frontiers Pane
Page 209 and 210:
PLANETARY SYSTEMS AND STAR FORMATIO
Page 211 and 212:
A preliminary recommended program w
Page 213 and 214:
certified as independent work perfo
Page 215 and 216:
penalty based on an assessment of s
Page 217 and 218:
The results show excellent correlat
Page 219 and 220:
$12 MILLION TO $40 MILLION RANGE CM
Page 221 and 222:
decadal research strategy with reco
Page 223 and 224:
CFP CHIPSat CIP CGRO CMB CMU CoBRA
Page 225 and 226:
NRC NSB NSF NSF-AGS NSF-ARC NSF-AST
show all

prepublication copy - The Department of Astronomy & Astrophysics ...

Create successful ePaper yourself

Delete template?

Save as template?