Multipole moments of bumpy black holes

General relativity predicts the existence of black holes, compact objects whose spacetimes depend on only their mass, spin, and charge in vacuum (the "no hair" theorem). As various observations probe deeper into the strong fields of black hole candidates, it is becoming possible to test this prediction. Previous work suggested that such tests can be performed by measuring whether the multipolar structure of black hole candidates has the form that general relativity demands, and introduced a family of "bumpy black hole" spacetimes to be used for making these measurements. These spacetimes have generalized multipoles, where the deviation from the Kerr metric depends on the spacetime's "bumpiness." In this paper, we show how to compute the Geroch-Hansen moments of a bumpy black hole, demonstrating that there is a clean mapping between the deviations used in the bumpy black hole formalism and the Geroch-Hansen moments. We also extend our previous results to define bumpy black holes whose {\it current} moments, analogous to magnetic moments of electrodynamics, deviate from the canonical Kerr value.Comment: 15 page

Bayesian inference for pulsar timing models

The extremely regular, periodic radio emission from millisecond pulsars makes them useful tools for studying neutron star astrophysics, general relativity, and low-frequency gravitational waves. These studies require that the observed pulse times of arrival be fit to complex timing models that describe numerous effects such as the astrometry of the source, the evolution of the pulsar's spin, the presence of a binary companion, and the propagation of the pulses through the interstellar medium. In this paper, we discuss the benefits of using Bayesian inference to obtain pulsar timing solutions. These benefits include the validation of linearized least-squares model fits when they are correct, and the proper characterization of parameter uncertainties when they are not; the incorporation of prior parameter information and of models of correlated noise; and the Bayesian comparison of alternative timing models. We describe our computational setup, which combines the timing models of Tempo2 with the nested-sampling integrator MultiNest. We compare the timing solutions generated using Bayesian inference and linearized least-squares for three pulsars: B1953+29, J2317+1439, and J1640+2224, which demonstrate a variety of the benefits that we posit.Comment: 13 pages, 4 figures, RevTeX 4.1. Revised in response to referee's suggestions; contains a broader discussion of model comparison, revised Monte Carlo runs, improved figure

Spacetime and orbits of bumpy black holes

Our universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine if they have the spacetime structure that general relativity demands. As a means of formulating measurements to test the black hole nature of these objects, Collins and Hughes introduced "bumpy black holes": objects that are almost, but not quite, general relativity's black holes. The spacetimes of these objects have multipoles that deviate slightly from the black hole solution, reducing to black holes when the deviation is zero. In this paper, we extend this work in two ways. First, we show how to introduce bumps which are smoother and lead to better behaved orbits than those in the original presentation. Second, we show how to make bumpy Kerr black holes -- objects which reduce to the Kerr solution when the deviation goes to zero. This greatly extends the astrophysical applicability of bumpy black holes. Using Hamilton-Jacobi techniques, we show how a spacetime's bumps are imprinted on orbital frequencies, and thus can be determined by measurements which coherently track a small orbiting body's orbital phase. We find that weak-field orbits of bumpy black holes are modified exactly as expected from a Newtonian analysis of a body with a prescribed multipolar structure, reproducing well-known results from the celestial mechanics literature. The impact of bumps on strong-field orbits is especially strong, suggesting that this framework will allow observations to set robust limits on the extent to which a spacetime's multipoles deviate from the black hole expectation.Comment: 24 pages, 3 figures, accepted to Phys. Rev. D. This version corrects some typos and incorporates suggested edit

The Temperance Crusade in American Fiction, 1830-1860

The American movement in support of temperance was especially strong from I830 to i860. During these decades, numerous authors used the medium of fiction to convince their readers of the values of abstinence from intoxicants. The purpose of this study is to examine a cross section of this fictional temperance literature in an effort to discover the viewpoints of these writers and to determine the attitudes toward antebellum American society which their works revealed. In order to investigate more fully the feelings of both the authors and the historically voiceless masses who made their works so popular, such concepts as status anxiety and projection were added to the usual methods of literary analysis. It would seem that both the authors and their receptive audience found the years prior to the Civil War filled with rapid change. Unable to adjust quickly to growing cities and increasing industrialism, and fearful of being left behind in a society turning in new directions, these people looked for reasons for their displacement and loss of status. In such a situation it was easy to believe that one factor, liquor, was the cause of much of their misfortune. Authors and their readers looked to the past and remembered an idealized time when beautiful, patient women and diligent men experienced only happiness. This Golden Age could be recaptured, they hopefully theorized, if only the menace of liquor could be eliminated. The literature which was written and the reception it received tell us a great deal about the fears, hopes, and ideals of the generation whose feelings it reflected

Improving the work of the Arctic Council: Challenges and recommendations

acceptedVersio

Mellomila 57

Neprofitna organizacija se definira kao pravna osoba osnovana zbog ostvarivanja javnog odnosno općeg interesa pojedinca ili grupe. Iz tog proizlazi da svrha organizacija nije ostvarivanje dobiti. Cilj rada je prikazati računovodstvo i poslovanje neprofitne organizacije na primjeru udruge Hrvatsko društvo za kontrolu bez razaranja. Prilikom sastavljanja rada korištena je literatura na hrvatskom, ali i na engleskom jeziku te određene internetske stranice. Udruga je obveznik poreza na dodanu vrijednost jer je vrijednost isporuka dobara ili obavljenih usluga u prethodnoj kalendarskoj godini bila veća od 230.000,00 kuna. Kako udruga obavlja i gospodarsku djelatnost, obveznik je i poreza na dobit te primjenjuje sustav dvojnog knjigovodstva. Pravilnikom o neprofitnom računovodstvu i računskom planu uređen je sadržaj i raspored te primjena računskog plana kojeg udruga primjenjuje. Udruga je upisana u Registar neprofitnih organizacija koji se vodi pri Ministarstvu financija jer sve organizacije koje nisu upisane u Registar, mogu biti kažnjene prema Zakonu o financijskom poslovanju i računovodstvu neprofitnih organizacija.A non-profit organization is defined as a legal entity established for achieving public or general interest of the individual or group. It follows that the purpose of the organization is not to make profits. The aim of this paper is to show the accounting and business of non-profit organizations in this case of the Croatian Society for Non-Destructive Testing. When compiling the paper not only Croatian literature was used, but also English and certain websites. The society is liable to pay value added tax because the value of the supply of goods or services performed in the previous calendar year exceeded 230,000.00 kunas. Since the society also carries out economic activities, it is liable for corporate tax and applies a double-entry bookkeeping. The Rulebook of non-profit accounting and chart of accounts arranges the content, layout and the appropriate use of the chart of accounts that the society applies. The association is registered in the Register of non-profit organizations kept by the Ministry of Finance because all the organizations that are not registered in the Register, can penalized under the Law on financial operations and acconunting of non-profit organizations