CLUSTERING AND LARGE SCALE STRUCTURE WITH THE SDSS

The Sloan Digital Sky Survey (SDSS) will provide a complete imaging and spectroscopic survey of the high-latitude northern sky. The 2D survey will image the sky in five colors and will contain nearly 5 x 107 galaxies to g ~ 23m. The spectroscopic survey will obtain spectra of the brightest 106 galaxies, 105 quasars, and 103.5 rich clusters of galaxies (to g~18.3-19.3m, respectively). I summarize some of the science opportunities that will be made possible by this survey for studying the clustering and large-scale structure of the universe. The survey will identify a complete sample of several thousand rich clusters of galaxies, both in 2D and 3D - the largest automated sample yet available. The extensive cluster sample can be used to determine critical clustering properties such as the luminosity-function, velocity-function, and mass-function of clusters of galaxies (a critical test for cosmological models), detailed cluster dynamics and W(dyn), the cluster correlation function and its dependence on richness, cluster evolution, superclustering and voids to the largest scales yet observed, the motions of clusters and their large-scale peculiar velocity field, as well as detailed correlations between x-ray and optical properties of clusters, the density-morphology relation, and cluster-quasar associations. The large redshift survey, reaching to a depth of 600h-1 Mpc, will accurately map the largest scales yet observed, determine the power-spectrum and correlation function on these large scales for different type galaxies, and study the clustering of quasars to high redshifts (z 4). The implications of the survey for cosmological models, the dark matter, and W are also discussed.Comment: compressed PostScript, invited talk presented at the AAS meeting, Minneapolis, June 1994, to appear in PASP 1995; for the figures contact [email protected]

United States budgetary costs of Post-9/11 wars through FY2018

Originally published on the Watson Institute's Costs of War Project website: http://watson.brown.edu/costsofwar/papers/2017/USBudgetaryCostsFY2018The costs to the United States of post-9/11 wars will total more than $5.6 trillion by the end of fiscal year 2018, a new Costs of War report finds, and the average American taxpayer has spent$23,386 on these wars since 2001. “The U.S. wars in Iraq, Syria, Afghanistan and Pakistan, and the increased spending on homeland security and the departments of defense, state and veterans affairs since the 9/11 attacks have cost more than $4.3 trillion in current dollars through fiscal year 2017,” said Neta Crawford, Costs of War co-director and a professor of political science at Boston University. “Adding likely costs for fiscal year 2018 and estimated future obligations for veterans’ care, the costs of war total more than$5.6 trillion.

Cosmology with Clusters of Galaxies

I show that three independent methods utilizing clusters of galaxies - cluster dynamics and mass-to-light ratio, baryon fraction in clusters, and cluster evolution - all indicate the same robust result: the mass-density of the universe is low, Omega ~ 0.2, and the mass approximately traces light on large scales.Comment: Invited talk at Nobel98, ``Particle Physics and the Universe,''8/1998, 15 pages, 4 figure

Concept paper on a curriculum initiative for energy, climate change, and sustainability at Boston University

[Summary] Boston University has made important contributions to the interconnected challenges of energy, climate change, and sustainability (ECS) through its research, teaching, and campus operations. This work reveals new opportunities to expand the scope of teaching and research and place the University at the forefront of ECS in higher education. This paper describes the framework for a University-wide curriculum initiative that moves us in that direction and that complements the University’s strategic plan. The central curricular objectives are to provide every undergraduate the opportunity be touched in some way in their educational program by exposure to some aspect of the ECS challenge, and to increase opportunities for every graduate student to achieve a focused competence in ECS. The initiative has six cornerstone initiatives. The first is the Campus as a Living Lab (CALL) program in which students, faculty and staff work together and use our urban campus and its community to study and implement ECS solutions. The second is a university-wide minor degree that helps students develop an integrated perspective of the economic, environmental, and social dimensions of sustainability. The third is one or more graduate certificate programs open to all graduate students. The fourth is an annual summer faculty workshop that develops new ECS curriculum and CALL opportunities. The fifth is web-based resource that underpins the construction of a vibrant knowledge network for the BU community and beyond. Finally, an enhanced sustainability alumni network will augment professional opportunities and generate other benefits. The learning outcomes of this initiative will be realized through the collaborative work of faculty, students, and staff from all 17 colleges and schools. The initiative will leverage existing BU student resources such as the Thurman Center, Build Lab, and Innovate@BU. Benefits of this initiative, beyond the curriculum, include acceleration towards the goals of our Climate Action Plan; improving the “sustainability brand” of BU; enhancing the ability to attract students and new faculty; strengthening our alumni and campus communities; deepening our ties with the city of Boston; and the potential to spin off new social and technological innovations.Published versio

Multi-View Kernels for Low-Dimensional Modeling of Seismic Events

The problem of learning from seismic recordings has been studied for years. There is a growing interest in developing automatic mechanisms for identifying the properties of a seismic event. One main motivation is the ability have a reliable identification of man-made explosions. The availability of multiple high-dimensional observations has increased the use of machine learning techniques in a variety of fields. In this work, we propose to use a kernel-fusion based dimensionality reduction framework for generating meaningful seismic representations from raw data. The proposed method is tested on 2023 events that were recorded in Israel and in Jordan. The method achieves promising results in classification of event type as well as in estimating the location of the event. The proposed fusion and dimensionality reduction tools may be applied to other types of geophysical data

The Small-Scale Environment of Quasars

Where do quasars reside? Are quasars located in environments similar to those of typical L* galaxies, and, if not, how do they differ? An answer to this question will help shed light on the triggering process of quasar activity. We use the Sloan Digital Sky Survey to study the environment of quasars and compare it directly with the environment of galaxies. We find that quasars (M_i < -22, z < 0.4) are located in higher local overdensity regions than are typical L* galaxies. The enhanced environment around quasars is a local phenomenon; the overdensity relative to that around L* galaxies is strongest within 100 kpc of the quasars. In this region, the overdensity is a factor of 1.4 larger than around L* galaxies. The overdensity declines monotonically with scale to nearly unity at ~1 Mpc, where quasars inhabit environments comparable to those of L* galaxies. The small-scale density enhancement depends on quasar luminosity, but only at the brightest end: the most luminous quasars reside in higher local overdensity regions than do fainter quasars. The mean overdensity around the brightest quasars (M_i < -23.3) is nearly three times larger than around L* galaxies while the density around dimmer quasars (M_i = -22.0 to -23.3) is ~1.4 times that of L* galaxies. By ~0.5 Mpc, the dependence on quasar luminosity is no longer significant. The overdensity on all scales is independent of redshift to z = 0.4. The results suggest a picture in which quasars typically reside in L* galaxies, but have a local excess of neighbors within ~0.1 - 0.5 Mpc; this local density excess likely contributes to the triggering of quasar activity through mergers and other interactions.Comment: Accepted by ApJ; 7 pages, 5 figure