Models of Galaxies with Central Black Holes: Simulation Methods

We present a method for simulating numerically the effect of the adiabatic growth of black holes on the structure of elliptical galaxies. Using a parallel self--consistent field code, we add black holes to N--body realizations of model distribution functions for spherical galaxies, using a continuous mass--spectrum. The variable particle mass, combined with a simple multiple timestep integration scheme, makes it possible to evolve the models for many dynamical times with $N \sim 10^6-10^8$, allowing high spatial and mass resolution. This paper discusses verification of the code using analytic models for spherical galaxies, comparing our numerical results of the effect of central black holes on the structure of the galaxies with previously published models. The intrinsic and projected properties of the final particle distribution, including higher order moments of the velocity distribution, permit comparison with observed characteristics of real galaxies, and constrain the masses of any central black holes present in those galaxies. Our technique is promising and is easily extended to axisymmetric and triaxial galaxies.Comment: 17 pages (incl. 11 figure) uuencoded postscript, Lick Preprint Series No. 3

Voice and resistance: coalminers' struggles to represent their health and safety interests in Australia and New Zealand 1871–1925

The activism of coalmining unions in Australia, the UK, the USA and elsewhere securing improvements in safety including better legislation in the 19th and 20th centuries, has been widely researched and acknowledged. However, a relatively neglected aspect of this history was a campaign to secure worker inspectors (check-inspectors). These began in coalmining a century before similar measures were introduced for workers more generally as part of overhauling occupational health and safety laws in the 1970s/1980s. We document this struggle for mine safety in Australia and New Zealand, and the activities of check-inspectors in the period to 1925. Notwithstanding strong opposition from coal-owners and conservative governments, check-inspectors played an important role in safeguarding coalminers and improving the regulatory oversight of coalmines. Check-inspectors not only gave coalminers a ‘voice’ in OHS, but they also provided an exemplar of the value and legitimacy of worker’s ‘knowledge activism’. This system remains. Furthermore, the struggle is relevant to understanding contemporary debates about collective worker involvement in occupational health and safety

The time-scale for core collapse in spherical star clusters

The collapse time for a cluster of equal-mass stars is usually stated to be either 330 central relaxation times (\trc) or 12--19 half-mass relaxation times (\trh). But the first of these times applies only to the late stages of core collapse, and the second only to low-concentration clusters. To clarify how the time depends on the mass distribution, the Fokker-Planck equation is solved for the evolution of a variety of isotropic cluster models, including King models, models with power-law density cusps of $\rho\sim r^{-\gamma}$, and models with nuclei. High-concentration King models collapse faster than low-concentration models if the time is measured in units of \trh, but slower if it is measured in units of \trc. Models with cusps evolve faster than King models, but not all of them collapse: those with $0<\gamma<2$ expand because they start with a temperature inversion. Models with nuclei collapse or expand as the nuclei would in isolation if their central relaxation times are short; otherwise their evolution is more complicated. Suggestions are made for how the results can be applied to globular clusters, galaxies, and hypothetical clusters of dark stars in the centers of galaxies.Comment: includes 10 postscript figs, uses psfig.sty (not included); submitted to New Astronom

Limited-capacity identity processing of multiple integers

The architecture of the numerical cognition system is currently not well understood, but at a general level, assumptions are made about two core components: a quantity processor and an identity processor. The quantity processor is concerned with accessing and using the stored magnitude denoted by a given digit. The identity processor is concerned with the recovery of the corresponding digit’s identity. Blanc-Goldhammer and Cohen (2014) established that the recovery and use of quantity information operates in an unlimited capacity fashion. Here, we assess whether the identity processor operates in a similar fashion. We present two experiments that are digit identity variations of Blanc-Goldhammer and Cohen’s (2014) magnitude estimation paradigm. The data across both experiments reveal a limited capacity identity processor whose operation reflects cross-talk with the quantity processor. Such findings provide useful evidence that is used to adjudicate between competing models of the human number processing system

System and Method for Modular Unmanned Aerial System

A modular Unmanned Aerial System (UAS) has first and second flight configurations, and includes an Unmanned Aerial Vehicle (UAV) parent module and a plurality of UAV child modules. The parent module may have a fuselage, forward and aft wings connected to the fuselage, and a first plurality of flight propulsion devices. The child modules have a corresponding second plurality of flight propulsion devices. Each child module docks wingtip-to-wingtip with the parent module or an adjacent edge of a child module using the docking mechanisms. The child modules undock and separate from the forward wing and each other, and achieve controlled flight independently of the parent module while in the second flight configuration. A method for controlling the modular UAS is also disclosed

The Merging History of Massive Black Holes

We investigate a hierarchical structure formation scenario describing the evolution of a Super Massive Black Holes (SMBHs) population. The seeds of the local SMBHs are assumed to be 'pregalactic' black holes, remnants of the first POPIII stars. As these pregalactic holes become incorporated through a series of mergers into larger and larger halos, they sink to the center owing to dynamical friction, accrete a fraction of the gas in the merger remnant to become supermassive, form a binary system, and eventually coalesce. A simple model in which the damage done to a stellar cusps by decaying BH pairs is cumulative is able to reproduce the observed scaling relation between galaxy luminosity and core size. An accretion model connecting quasar activity with major mergers and the observed BH mass-velocity dispersion correlation reproduces remarkably well the observed luminosity function of optically-selected quasars in the redshift range 1<z<5. We finally asses the potential observability of the gravitational wave background generated by the cosmic evolution of SMBH binaries by the planned space-born interferometer LISA.Comment: 4 pages, 2 figures, Contribute to "Multiwavelength Cosmology", Mykonos, Greece, June 17-20, 200