3,017 research outputs found
: a new compilation of the Milky Way rotation curve data
We present , 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
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
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
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
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
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
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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