3,017 research outputs found

    galkin\texttt{galkin}: a new compilation of the Milky Way rotation curve data

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    We present galkin\texttt{galkin}, a novel compilation of kinematic measurements tracing the rotation curve of our Galaxy, together with a tool to treat the data. The compilation is optimised to Galactocentric radii between 3 and 20 kpc and includes the kinematics of gas, stars and masers in a total of 2780 measurements carefully collected from almost four decades of literature. A simple, user-friendly tool is provided to select, treat and retrieve the data of all source references considered. This tool is especially designed to facilitate the use of kinematic data in dynamical studies of the Milky Way with various applications ranging from dark matter constraints to tests of modified gravity.Comment: Description of out-of-the-box public tool to treat data compilation first used in Nature Physics 11, 245-248 (2015). Please cite SoftwareX and Nature Physics papers together. Refer to https://github.com/galkintool/galkin for source code and additional informatio

    Lithium synthesis in microquasar accretion

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    We study the synthesis of lithium isotopes in the hot tori formed around stellar mass black holes by accretion of the companion star. We find that sizable amounts of both stable isotopes 6Li and 7Li can be produced, the exact figures varying with the characteristics of the torus and reaching as much as 1e-2 Msun for each isotope. This mass output is enough to contaminate the entire Galaxy at a level comparable with the original, pre-galactic amount of lithium and to overcome other sources such as cosmic-ray spallation or stellar nucleosynthesis

    Mapping dark matter in the Milky Way, a synopsis

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    Mapping the dark matter distribution across our Galaxy represents a central challenge for the near future as a new generation of space-borne and ground-based astronomical surveys swiftly comes online. Here we present a synopsis of the present status of the field, reviewing briefly the baryonic content and the kinematics of the Milky Way and outlining the methods used to infer the dark matter component. The discussion then proceeds with some of the latest developments based on our own work. In particular, we present a new compilation of kinematic measurements tracing the rotation curve of the Galaxy and an exhaustive array of observation-based baryonic models setting the contribution of stellar bulge, stellar disc and gas to the total gravitational potential. The discrepancy between these two components is then quantified to derive the latest constraints on the dark matter distribution and on modified Newtonian dynamics. We shall end with an overview of future directions to improve our mapping of the dark matter distribution in the Milky Way.Comment: Proceedings of highlight talk at the 34th International Cosmic Ray Conference, 30 July-6 August, 2015, The Hague, The Netherlands, 16 pages, 2 figures, 1 tabl

    Missing levels in correlated spectra

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    Complete spectroscopy (measurements of a complete sequence of consecutive levels) is often considered as a prerequisite to extract fluctuation properties of spectra. It is shown how this goal can be achieved even if only a fraction of levels are observed. The case of levels behaving as eigenvalues of random matrices, of current interest in nuclear physics, is worked out in detail.Comment: 14 pages and two figure

    Testing modified Newtonian dynamics in the Milky Way

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    Modified Newtonian dynamics (MOND) is an empirical theory originally proposed to explain the rotation curves of spiral galaxies by modifying the gravitational acceleration, rather than by invoking dark matter. Here,we set constraints on MOND using an up-to-date compilation of kinematic tracers of the Milky Way and a comprehensive collection of morphologies of the baryonic component in the Galaxy. In particular, we find that the so-called "standard" interpolating function cannot explain at the same time the rotation curve of the Milky Way and that of external galaxies for any of the baryonic models studied, while the so-called "simple" interpolating function can for a subset of models. Upcoming astronomical observations will refine our knowledge on the morphology of baryons and will ultimately confirm or rule out the validity of MOND in the Milky Way. We also present constraints on MOND-like theories without making any assumptions on the interpolating function.Comment: 6 pages, 3 figure

    Dynamical constraints on the dark matter distribution in the Milky Way

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    An accurate knowledge of the dark matter distribution in the Milky Way is of crucial importance for galaxy formation studies and current searches for particle dark matter. In this paper we set new dynamical constraints on the Galactic dark matter profile by comparing the observed rotation curve, updated with a comprehensive compilation of kinematic tracers, with that inferred from a wide range of observation-based morphologies of the bulge, disc and gas. The generalised Navarro-Frenk-White (NFW) and Einasto dark matter profiles are fitted to the data in order to determine the favoured ranges of local density, slope and scale radius. For a representative baryonic model, a typical local circular velocity of 230 km/s and a distance of the Sun to the Galactic centre of 8 kpc, we find a local dark matter density of 0.420+0.021-0.018 (2 sigma) +- 0.025 GeV/cm^3 (0.420+0.019-0.021 (2 sigma) +- 0.026 GeV/cm^3) for NFW (Einasto), where the second error is an estimate of the systematic due to baryonic modelling. Apart from the Galactic parameters, the main sources of uncertainty inside and outside the solar circle are baryonic modelling and rotation curve measurements, respectively. Upcoming astronomical observations are expected to reduce all these uncertainties substantially over the coming years.Comment: 10 pages, 5 figures, 2 tables, matches published versio

    Pinpointing Cosmic Ray Propagation With The AMS-02 Experiment

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    The Alpha Magnetic Spectrometer (AMS-02), which is scheduled to be deployed onboard the International Space Station later this year, will be capable of measuring the composition and spectra of GeV-TeV cosmic rays with unprecedented precision. In this paper, we study how the projected measurements from AMS-02 of stable secondary-to-primary and unstable ratios (such as boron-to-carbon and beryllium-10-to-beryllium-9) can constrain the models used to describe the propagation of cosmic rays throughout the Milky Way. We find that within the context of fairly simple propagation models, all of the model parameters can be determined with high precision from the projected AMS-02 data. Such measurements are less constraining in more complex scenarios, however, which allow for departures from a power-law form for the diffusion coefficient, for example, or for inhomogeneity or stochasticity in the distribution and chemical abundances of cosmic ray sources.Comment: 12 pages, 7 figures, 3 tables, matches published versio
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