How do galaxies acquire their mass?

We introduce a toy model that describes (in a single equation) the mass in stars as a function of halo mass and redshift. Our model includes the suppression of gas accretion from gravitational shock heating and AGN jets mainly for M_halo > M_shock ~ 10^12 M_Sun and from a too hot IGM onto haloes with v_circ < 40 km/s, as well as stellar feedback that drives gas out of haloes mainly with v_circ < 120 km/s. We run our model on the merger trees of the haloes and subhaloes of a high-resolution dark matter cosmological simulation. The galaxy mass is taken as the maximum between the mass given by the model and the sum of the masses of its progenitors (reduced by tidal stripping). Designed to reproduce the present-day stellar mass function of galaxies, our model matches fairly well the evolution of the cosmic stellar density. It leads to the same z=0 relation between central galaxy stellar and halo mass as the one found by abundance matching and also as that previously measured at high mass on SDSS centrals. Our model also predicts a bimodal distribution (centrals and satellites) of stellar masses for given halo mass, in good agreement with SDSS observations. The relative importance of mergers depends much more on stellar than halo mass. Galaxies with m_stars > 10^11 M_Sun/h acquire most of their mass through mergers (mostly major and gas-poor), as expected from our model's shutdown of gas accretion at high M_halo. However, mergers are rare for m_stars < 10^11 M_Sun/h (greater than our mass resolution), a consequence of the curvature of the stellar vs. halo mass relation. So gas accretion must be the dominant growth mechanism for intermediate and low mass galaxies, e.g. dwarf ellipticals in clusters, except that gas-rich galaxy mergers account for the bulk of the growth of ellipticals with m_stars ~ 10^10.5 M_Sun/h, which we predict must be the typical mass of ULIRGs.Comment: 18 pages, 12 figures, A&A in press (major re-write and updated figures from version 1

On the backreaction of frame dragging

The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, J^{BH}=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j^2>1, which is related to the behaviour of the ring angular velocity. Using the `gravitomagnetic clock effect', for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with J^{BH}\neq 0.Comment: 18 pages, 8 figure

Selecting a Trust Situs in the 21st Century

While members of Congress vigorously debate the advantages and disadvantages of keeping the current transfer tax system, states rapidly are enacting laws that entice long-term trusts to those states. Although establishing or relocating a trust to a state other than the grantor\u27s home state is not for every family, it is a planning technique that merits consideration by families with significant assets. The chart on pages 60-63 provides general information on the laws of all fifty states. This article focuses on three specific considerations related to selecting a favorable trust situs. First, it considers the effect of recent repeals or modifications of the Rule Against Perpetuities (RAP). Within this context, this article primarily focuses on generation-skipping transfer tax (GST Tax) implications. Second, it considers ways to carefully select a situs that can provide families with protection from creditors. Finally, the article examines ways to use favorable state tax laws to reduce a client\u27s state income tax. After discussing these three specific considerations, the article examines some general considerations related to trust situs

Cohesion: Uniting Reading and Writing!

The purpose of this text, or should we say guide, is to help all students in English composition classes - whether stand-alone or coupled with reading courses - understand the connections and the cohesive aspect of reading and writing. The authors used their own years of teaching both reading and writing, for all levels in college, to explain concepts in a straightforward and clear manner for students. The goal is that this becomes a resource - a FREE resource – students can return to time and time again when they have questions or need a refresher even after their English composition course ends

Economic Impact and Significance: Additional Insights for Measurement in Special Events

Abstract Special events are an important component of the tourism industry, and they attract visitors to areas where they are hosted. These events have an economic impact and significance in the local host communities, since the visitors will spend money during their travel and visits to these destinations that bring benefits. While substantial effort has been made in the past to measure the economic impact of attractions and destinations, less time has been spent on adapting these measures for the measurement of periodic special events. The purpose of this study is to further examine and update the measurement concepts associated with assessing the economic impact and significance of three different special events. Specifically, this study examined and further the study of these economic impact measurements through the examination and application of EIS measurement techniques to three events in Western Massachusetts: Great New England Air Show, Volleyball Hall of Fame Events, and Westfield International Air Show

Experiencing the Event Brand: Examining the Branded Images for a New England Regional Fair

Introduction. Brands and branding are critical to the understanding and perception of destinations and products and now events are even “branded. ” Some of these events have had a long history, and may or may not have been intentionally ‘branded ” but contain images and perceptions of a ‘branded event ” by different types of event consumers. Clearly different types of event consumers likely have different brand images of the same event or in this study- a regiona

Semi-classical stability of AdS NUT instantons

The semi-classical stability of several AdS NUT instantons is studied. Throughout, the notion of stability is that of stability at the one-loop level of Euclidean Quantum Gravity. Instabilities manifest themselves as negative eigenmodes of a modified Lichnerowicz Laplacian acting on the transverse traceless perturbations. An instability is found for one branch of the AdS-Taub-Bolt family of metrics and it is argued that the other branch is stable. It is also argued that the AdS-Taub-NUT family of metrics are stable. A component of the continuous spectrum of the modified Lichnerowicz operator on all three families of metrics is found.Comment: 18 pages, 3 figures; references adde

National Park Service Visitation and Search Behavior: An Update to 2010

Abstract This purpose of this paper was to examine and update recent findings that proposes that national park visitation is on the decline and to propose other methods for examining the interest in national parks through online searches related to travel intentions. Data from a large, national syndicated secondary dataset were examined by individual participation data collected on an annual basis over the period of 2000-2010. In addition, inquiry data from Google Insights™ for vacation travel to national and state parks was also used as a proxy measure to determine if interest had declined. While there was evidence of some decline in visitation to national parks from 2000-2010, most of the decline was limited to the period of 2000-2004; however, there was also a rebound in interest from 2004 through 2010 with the exception of 2008. The decline does not appear to be dramatic. The decline is not related to a decrease in the market size of individuals interested in national parks but rather a volume issue. The volume issue suggests that the base market of people interested in national parks still exists, but the base market is making fewer visits per visitor to national parks. Additional insights into visitation based on media use (e.g., watching tv and internet use) based on volume segments were explored. There was some indication of decline of interest in visiting national parks during vacation travel through the analysis of Google Insights™ search behavior; however, this decline has been cyclical, not overly dramatic, and appears to reflect the changes in visitation noted here through the national syndicated dataset findings. Interest may also have shifted to other outdoor pursuits and interests via an increase in more choices. Interest in state parks appeared to also be seasonal; but no dramatic decline in the interest in state parks was noted based on Internet searches and Google Insights™ analysis

Simple generalizations of Anti-de Sitter space-time

We consider new cosmological solutions which generalize the cosmological patch of the Anti-de Sitter (AdS) space-time, allowing for fluids with equations of state such that $w\neq -1$. We use them to derive the associated full manifolds. We find that these solutions can all be embedded in flat five-dimensional space-time with $--+++$ signature, revealing deformed hyperboloids. The topology and causal-structure of these spaces is therefore unchanged, and closed time-like curves are identified, before a covering space is considered. However the structure of Killing vector fields is entirely different and so we may expect a different structure of Killing horizons in these solutions.Comment: 6 Pages, 5 Figures, Corrections and additions made for publication in Journal of Classical and Quantum Gravit