The fate of cannibalized fundamental-plane ellipticals

Evolution and disruption of galaxies orbiting in the gravitational field of a larger cluster galaxy are driven by three coupled mechanisms: 1) the heating due to its time dependent motion in the primary; 2) mass loss due to the tidal strain field; and 3) orbital decay. Previous work demonstrated that tidal heating is effective well inside the impulse approximation limit. Not only does the overall energy increase over previous predictions, but the work is done deep inside the secondary galaxy, e.g. at or inside the half mass radius in most cases. Here, these ideas applied to cannibalization of elliptical galaxies with fundamental-plane parameters. In summary, satellites which can fall to the center of a cluster giant by dynamical friction are evaporated by internal heating by the time they reach the center. This suggests that true merger-produced multiple nuclei giants should be rare. Specifically, secondaries with mass ratios as small as 1\% on any initial orbit evaporate and those on eccentric orbits with mass ratios as small as 0.1\% evolve significantly and nearly evaporate in a galaxian age. Captured satellites with mass ratios smaller than roughly 1\% have insufficient time to decay to the center. After many accretion events, the model predicts that the merged system has a profile similar to that of the original primary with a weak increase in concentration.Comment: 19 pages, 10 Postscript figures, uses aaspp4.sty. Submitted to Astrophysical Journa

Ultraviolet Divergences in Cosmological Correlations

A method is developed for dealing with ultraviolet divergences in calculations of cosmological correlations, which does not depend on dimensional regularization. An extended version of the WKB approximation is used to analyze the divergences in these calculations, and these divergences are controlled by the introduction of Pauli--Villars regulator fields. This approach is illustrated in the theory of a scalar field with arbitrary self-interactions in a fixed flat-space Robertson--Walker metric with arbitrary scale factor $a(t)$. Explicit formulas are given for the counterterms needed to cancel all dependence on the regulator properties, and an explicit prescription is given for calculating finite regulator-independent correlation functions. The possibility of infrared divergences in this theory is briefly considered.Comment: References added on various regularization methods. Improved discussion of further issues. 26 pages, 1 figur

Production of Milky Way structure by the Magellanic Clouds

Previous attempts at disturbing the galactic disk by the Magellanic Clouds relied on direct tidal forcing. However, by allowing the halo to actively respond rather than remain a rigid contributor to the rotation curve, the Clouds may produce a wake in the halo which then distorts the disk. Recent work reported here suggests that the Magellanic Clouds use this mechanism to produce disk distortions sufficient to account for both the radial location, position angle and sign of the HI warp and observed anomalies in stellar kinematics towards the galactic anticenter and LSR motion.Comment: 8 pages, uuencoded compressed PostScript, no figures, html version with figures and mpeg simulations available at http://www-astro.phast.umass.edu/Preprints/martin/martin1/lmc_online.htm

Preliminary study of contaminant particulates around Skylab

Techniques originally developed for the Skylab T025 contamination experiment were applied to S052 white-light coronagraph data in a preliminary study to investigate particulates around Skylab. Periods were selected which contained some contamination, even though there were no apparent dumps or vents during these periods. Velocity and size distributions were determined from optical data for particles within 200 meters of the spacecraft. Both photographic (61 particle tracks) and video (34 particles) observations yield an upper limit on particle radius of 100 micrometers. Selected photometric data from the S073 zodiacal light experiment during mission SL-2 were also examined for evidence of contamination

Photoelectric polarimetry of the tail of comet Ikey-Seki (1975 VIII)

Post-perihelion measurements of Comet 1965 VIII made on four nights in October-November 1965 using a Fabry photometer atop 3,052 m Mt. Haleakala, Hawaii are described. Detailed results of observations at 5300A on October 29, 1965 are presented

A Test of the Adhesion Approximation for Gravitational Clustering

We quantitatively compare a particle implementation of the adhesion approximation to fully non--linear, numerical nbody simulations. Our primary tool, cross--correlation of nbody simulations with the adhesion approximation, indicates good agreement, better than that found by the same test performed with the Zel'dovich approximation (hereafter ZA). However, the cross--correlation is not as good as that of the truncated Zel'dovich approximation (TZA), obtained by applying the Zel'dovich approximation after smoothing the initial density field with a Gaussian filter. We confirm that the adhesion approximation produces an excessively filamentary distribution. Relative to the nbody results, we also find that: (a) the power spectrum obtained from the adhesion approximation is more accurate than that from ZA or TZA, (b) the error in the phase angle of Fourier components is worse than that from TZA, and (c) the mass distribution function is more accurate than that from ZA or TZA. It appears that adhesion performs well statistically, but that TZA is more accurate dynamically, in the sense of moving mass to the right place. Subject Heading: Galaxies, formation, clustering--large--scale structure of the UniverseComment: TeX, 7 pages excluding figures (contact [email protected]). submitted to Ap

Carbon monoxide oxidation catalysis over Ir(110)

N/

A Magellanic Origin for the Warp of the Galaxy

We show that a Magellanic Cloud origin for the warp of the Milky Way can explain most quantitative features of the outer HI layer recently identified by Levine, Blitz & Heiles (2005). We construct a model similar to that of Weinberg (1998) that produces distortions in the dark matter halo, and we calculate the combined effect of these dark-halo distortions and the direct tidal forcing by the Magellanic Clouds on the disk warp in the linear regime. The interaction of the dark matter halo with the disk and resonances between the orbit of the Clouds and the disk account for the large amplitudes observed for the vertical m=0,1,2 harmonics. The observations lead to six constraints on warp forcing mechanisms and our model reasonably approximates all six. The disk is shown to be very dynamic, constantly changing its shape as the Clouds proceed along their orbit. We discuss the challenges to MOND placed by the observations.Comment: 4 pages, 3 figures, submitted to ApJ Letters. Additional graphics, 3d visualizations and movies available at http://www.astro.umass.edu/~weinberg/lm

Testing the Isotropy of the Universe with Type Ia Supernovae

We analyze the magnitude-redshift data of type Ia supernovae included in the Union and Union2 compilations in the framework of an anisotropic Bianchi type I cosmological model and in the presence of a dark energy fluid with anisotropic equation of state. We find that the amount of deviation from isotropy of the equation of state of dark energy, the skewness \delta, and the present level of anisotropy of the large-scale geometry of the Universe, the actual shear \Sigma_0, are constrained in the ranges -0.16 < \delta < 0.12 and -0.012 < \Sigma_0 < 0.012 (1\sigma C.L.) by Union2 data. Supernova data are then compatible with a standard isotropic universe (\delta = \Sigma_0 = 0), but a large level of anisotropy, both in the geometry of the Universe and in the equation of state of dark energy, is allowed.Comment: 12 pages, 7 figures, 2 tables. Union2 analysis added. New references added. To appear in Phys. Rev.

Semiclassical Calculation of Multiparticle Scattering Cross Sections in Classicalizing Theories

It has been suggested in arXiv:1010.1415 that certain derivatively coupled non-renormalizable scalar field theories might restore the perturbative unitarity of high energy hard scatterings by classicalization, i.e. formation of multiparticle states of soft quanta. Here we apply the semiclassical method of calculating the multiparticle production rates to the scalar Dirac-Born-Infeld (DBI) theory which is suggested to classicalize. We find that the semiclassical method is applicable for the energies in the final state above the cutoff scale of the theory L_*^{-1}. We encounter that the cross section of the process two to N ceases to be exponentially suppressed for the particle number in the final state N smaller than a critical particle number N_{crit} ~ (E L_*)^{4/3}. It coincides with the typical particle number produced in two-particle collisions at high energies predicted by classicalization arguments.Comment: 17 pages, 4 figures, v2. Minor changes to match the published versio