Russia's non-strategic nuclear forces

This article provides a brief overview of current debates in Russia on nuclear weapons before examining several factors that suggest that Moscow's interest in arms control arrangements affecting its NSNF is likely to be limited. Indeed, while Moscow has maintained its demands since the 1950s that all US nuclear forces in Europe be removed, its willingness to retain existing arms control limits such as the Intermediate-range Nuclear Forces (INF) Treaty and less formal obligations such as the 1991-2 unilaterial commitments on NSNF may be in decline. Moreover, Russia's implementation of the latter commitments remains unclear. The prospects for Moscow's endorsing new negotiated constraints on Russian NSNF therefore appears doubtful

The Reykjavik Summit and European Security

Many West Europeans have agreed in retrospect that the most disturbing feature of the Reykjavik summit was the apparent "indifference or quasi-indifference" of the United States regarding European security interests. 1 This judgment is based on the specific arms-control arrangements that President Reagan and General Secretary Gorbachev discussed in Iceland in October 1986, plus the subsequent explanations of the U.S. administration. The Reykjavik summit also provided fresh evidence of the Soviet Union's more imaginative diplomatic style under Gorbachev and, more substantively, of enduring Soviet preferences regarding security in Europe

Ballistic Missile Defense and the Atlantic Alliance

The Atlantic Alliance may be at the threshold of a new debate on the implications of ballistic missile defense (BMD) for European security. Secretary of Defense Caspar Weinberger and several U.S. Senators and Congressmen support a thorough review of U.S. BMD options, including possible revision of the 1972 Anti- Ballistic Missile (ABM) Treaty and its 1974 Protocol. Although active defense of intercontinental ballistic missiles (ICBMs) seems the most likely application for BMD, other strategic defense options are reportedly under consideration. European-based BMD against theater ballistic missiles such as the SS-20, SS- 21, SS-22, and SS-23 is being examined as well. Such defenses are known as anti-tactical ballistic missiles (ATBM) or anti-tactical missiles (ATM). The term “ATM” is preferred in that it implies capability against cruise as well as ballistic missiles

The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) Program. III. Optical Spectroscopy

We present the catalog of 477 spectra from the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program, a survey designed to probe the dominant contributors to the 2-10 keV cosmic X-ray background. Our survey covers 1 deg^2 of sky to 2-10 keV fluxes of 10^-14 erg cm^-2 s^-1, and 2 deg^2 for fluxes of 3 x 10^-14 erg cm^-2 s^-1. Our spectra reach to R <24 and have produced redshifts for 438 hard X-ray sources. The vast majority of the 2-10 keV-selected sample are AGN with redshifts between 0.1 and 3. We find that few sources at z<1 have high X-ray luminosities, reflecting a dearth of high-mass, high-accretion-rate sources at low redshift, a result consistent with other recent wide-area surveys. Half of our sources show significant obscuration, with N_H>10^22 cm^-2, independent of unobscured luminosity. We classify 168 sources as emission-line galaxies; all are X-ray luminous objects with optical spectra lacking both high-ionization lines and evidence of a non-stellar continuum. The redshift distribution of these emission-line galaxies peaks at a significantly lower redshift than does that of the sources we spectroscopically identify as AGN. We conclude that few of these sources can be powered by starburst activity. Stacking spectra for a subset of these sources, we detect [Ne V] emission, a clear signature of AGN activity, confirming that the majority of these objects are Seyfert 2s in which the high-ionization lines are diluted by stellar emission. We find 33 objects lacking broad lines in their optical spectra which have quasar X-ray luminosities (Lx>10^44 erg s^-1), the largest sample of such objects identified to date. In addition, we explore 17 AGN associated with galaxy clusters and find that the cluster-member AGN sample has a lower fraction of broad-line AGN than does the background sample.Comment: Accepted to ApJ; 57 pages, 25 figures, 5 table

A Galaxy at z = 6.545 and Constraints on the Epoch of Reionization

We report the discovery of a Lyman-alpha-emitting galaxy at redshift z=6.545 serendipitously identified in the course of spectroscopic follow-up of hard X-ray sources on behalf of the Serendipitous Extragalactic X-Ray Source Identification (SEXSI) survey. The line flux of the galaxy, 2.1e-17 erg/cm2/s, is similar to line fluxes probed by narrow-band imaging surveys; the 5.2 square-arcminutes surveyed implies a surface density of z~6.5 Lyman-alpha emitters somewhat higher than that inferred from narrow-band surveys. This source marks the sixth Lyman-alpha-emitting galaxy identified at z~6.5, a redshift putatively beyond the epoch of reionization when the damping wings of the neutral hydrogen of the intergalactic medium is capable of severely attenuating Lyman-alpha emission. By comparing the Lyman-alpha emitter luminosity functions at z~5.7 and z~6.5, we infer that the intergalactic medium may remain largely reionized from the local universe out to z~6.5.Comment: 16 pages, 4 figures; submitted to the Astrophysical Journa

Direct Integration and Non-Perturbative Effects in Matrix Models

We show how direct integration can be used to solve the closed amplitudes of multi-cut matrix models with polynomial potentials. In the case of the cubic matrix model, we give explicit expressions for the ring of non-holomorphic modular objects that are needed to express all closed matrix model amplitudes. This allows us to integrate the holomorphic anomaly equation up to holomorphic modular terms that we fix by the gap condition up to genus four. There is an one-dimensional submanifold of the moduli space in which the spectral curve becomes the Seiberg--Witten curve and the ring reduces to the non-holomorphic modular ring of the group $\Gamma(2)$. On that submanifold, the gap conditions completely fix the holomorphic ambiguity and the model can be solved explicitly to very high genus. We use these results to make precision tests of the connection between the large order behavior of the 1/N expansion and non-perturbative effects due to instantons. Finally, we argue that a full understanding of the large genus asymptotics in the multi-cut case requires a new class of non-perturbative sectors in the matrix model.Comment: 51 pages, 8 figure