Dynamical evolution of globular cluster systems in clusters of galaxies I. The case of NGC 1404 in the Fornax cluster

We investigate, via numerical simulations, the tidal stripping and accretion of globular clusters (GCs). In particular, we focus on creating models that simulate the situation for the GC systems of NGC 1404 and NGC 1399 in the Fornax cluster, which have poor (specific frequency $S_{\rm N}$ $\sim$ 2) and rich ($S_{\rm N}$ $\sim$ 10) GC systems respectively. We initially assign NGC 1404 in our simulation a typical $S_{\rm N}$ ($\sim$ 5) for cluster ellipticals, and find that its GC system can only be reduced through stripping to the presently observed value, if its orbit is highly eccentric (with orbital eccentricity of $>$ 0.5) and if the initial scale length of the GCs system is about twice as large as the effective radius of NGC 1404 itself. These stripped GCs can be said to have formed a `tidal stream' of intracluster globular clusters (ICGCs) orbiting the centre of Fornax cluster (many of which would be assigned to NGC 1399 in an imaging study). The physical properties of these GCs (e.g., number, radial distribution) depend on the orbit and initial distribution of GCs in NGC 1404. Our simulations also predict a trend for $S_{\rm N}$ to rise with increasing clustercentric distance - a trend for which there is some observational support in the Fornax cluster.Comment: 12 pages 12 figures, MNRAS in pres

Telemetric Observations of Foraging Ozark Big-Eared Bats in Arkansas

Ozark big-eared bat (Corynorhinus townsendii ingens) foraging activities were studied during 1995 in Marion County, Arkansas. Adult bats were equipped with radiotransmitters and tracked during June and July. Foraging activities were generally within 1 kilometer (km) of the roost cave. Male bats ranged farther than females with the exception of one female that flew 2.5 km into a different watershed. Male big-eared bats and northern long-eared bats (Myotis septentrionalis) were also found within the maternity colony

Imaging and spectroscopy of galaxies associated with two z~0.7 damped Lyman-alpha absorption systems

We have identified galaxies near two quasars which are at the redshift of damped Lyman-alpha (DLA) systems in the UV spectra of the quasars. Both galaxies are actively forming stars. One galaxy has a luminosity close to the break in the local galaxy luminosity function, L*, the other is significantly fainter than L* and appears to be interacting with a nearby companion. Despite the strong selection effects favoring spectroscopic identification of the most luminous DLA galaxies, many of the spectroscopically-identified DLA galaxies in the literature are sub-L*, suggesting that the majority of the DLA population is probably sub-L*, in contrast to MgII absorbers at similar redshifts whose mean luminosity is close to L*.Comment: 9 pages, to appear in AJ, November 2003 issu

Polymerisable octahedral rhenium cluster complexes as precursors for photo/electroluminescent polymers

New polymerisable photoluminescent octahedral rhenium cluster complexes trans-[{Re₆Q₈}(TBP)₄VB)₂] (Q = S or Se; TBP – p-tert-butylpyridine; VB – vinyl benzoate) have been synthesised, characterised and used to construct rhe-nium cluster-organic polymer hybrid materials. These novel polymer systems are solution-processable and the rhenium clusters retain their photoluminescent properties within the polymer environment. Notably, when the rhenium cluster complexes are incorporated into the matrix of the electroluminescent polymer poly(N-vinylcarbazole), the resultant cluster polymer hybrid combined properties of both components and was used successfully in the construc-tion of a polymer light emitting diode (PLED). These prototype devices are the first PLEDs to incorporate octahedral rhenium clusters and provide the first direct evidence of the electroluminescent properties of rhenium clusters and indeed, to the best of our knowledge, of any member of the family of 24-electron hexanuclear cluster complexes of molybdenum, tungsten or rhenium

Semileptonic BcB_c Decay and Heavy Quark Spin Symmetry

Semileptonic decay of the $B_c$ meson is studied in the heavy quark limit. The six possible form factors for $B_c \rightarrow B_s (B^0),B_s^* (B^{*0})$ semileptonic decay are determined by two invariant functions. Only one of these functions contributes at zero recoil, where it is calculable to lowest order in an operator product expansion in terms of the meson decay constant $f_B$ and the $B_c$ wavefunction. A similar result is found for $B_c \rightarrow D^0,D^{*0}$ and for $B_c\rightarrow\eta_c,J/\psi$ semileptonic decay for a restricted kinematic region. Semileptonic $B_c$ decay provides a means for determining the KM mixing angle $|V_{ub}|$.Comment: (12 Pages, no figures

CAIRNS: The Cluster And Infall Region Nearby Survey I. Redshifts and Mass Profiles

The CAIRNS (Cluster And Infall Region Nearby Survey) project is a spectroscopic survey of the infall regions surrounding eight nearby, rich, X-ray luminous clusters of galaxies. We collect 15665 redshifts (3471 new or remeasured) within \sim 5-10 Mpc of the centers of the clusters, making it the largest study of the infall regions of clusters. We determine cluster membership and the mass profiles of the clusters based on the phase space distribution of the galaxies. All of the clusters display decreasing velocity dispersion profiles. The mass profiles are fit well by functional forms based on numerical simulations but exclude an isothermal sphere. Specifically, NFW and Hernquist models provide good descriptions of cluster mass profiles to their turnaround radii. Our sample shows that the predicted infall pattern is ubiquitous in rich, X-ray luminous clusters over a large mass range. The caustic mass estimates are in excellent agreement with independent X-ray estimates at small radii and with virial estimates at intermediate radii. The mean ratio of the caustic mass to the X-ray mass is 1.03\pm0.11 and the mean ratio of the caustic mass to the virial mass (when corrected for the surface pressure term) is 0.93\pm0.07. We further demonstrate that the caustic technique provides reasonable mass estimates even in merging clusters.Comment: 54 pages, 18 figures, to appear in The Astronomical Journa

Predicting the cosmological constant with the scale-factor cutoff measure

It is well known that anthropic selection from a landscape with a flat prior distribution of cosmological constant Lambda gives a reasonable fit to observation. However, a realistic model of the multiverse has a physical volume that diverges with time, and the predicted distribution of Lambda depends on how the spacetime volume is regulated. We study a simple model of the multiverse with probabilities regulated by a scale-factor cutoff, and calculate the resulting distribution, considering both positive and negative values of Lambda. The results are in good agreement with observation. In particular, the scale-factor cutoff strongly suppresses the probability for values of Lambda that are more than about ten times the observed value. We also discuss several qualitative features of the scale-factor cutoff, including aspects of the distributions of the curvature parameter Omega and the primordial density contrast Q.Comment: 16 pages, 6 figures, 2 appendice

Hydrodynamical Simulations of the Lyman Alpha Forest: Model Comparisons

We investigate the properties of the Lyman alpha forest as predicted by numerical simulations for a range of currently viable cosmological models. This is done in order to understand the dependencies of the forest on cosmological parameters. Focusing on the redshift range from two to four, we show that: (1) most of the evolution in the distributions of optical depth, flux and column density can be understood by simple scaling relations, (2) the shape of optical depth distribution is a sensitive probe of the amplitude of density fluctuations on scales of a few hundred kpc, (3) the mean of the b distribution (a measure of the width of the absorption lines) is also very sensitive to fluctuations on these scales, and decreases as they increase. We perform a preliminary comparison to observations, where available. A number of other properties are also examined, including the evolution in the number of lines, the two-point flux distribution and the HeII opacity.Comment: 37 pages, 21 figures, submitted to Ap

Aerial Deployment and Inflation System for Mars Helium Balloons

A method is examined for safely deploying and inflating helium balloons for missions at Mars. The key for making it possible to deploy balloons that are light enough to be buoyant in the thin, Martian atmosphere is to mitigate the transient forces on the balloon that might tear it. A fully inflated Mars balloon has a diameter of 10 m, so it must be folded up for the trip to Mars, unfolded upon arrival, and then inflated with helium gas in the atmosphere. Safe entry into the Martian atmosphere requires the use of an aeroshell vehicle, which protects against severe heating and pressure loads associated with the hypersonic entry flight. Drag decelerates the aeroshell to supersonic speeds, then two parachutes deploy to slow the vehicle down to the needed safe speed of 25 to 35 m/s for balloon deployment. The parachute system descent dynamic pressure must be approximately 5 Pa or lower at an altitude of 4 km or more above the surface