3,076 research outputs found
Prescriptions on antiproton cross section data for precise theoretical antiproton flux predictions
After the breakthrough from the satellite-borne PAMELA detector, the flux of
cosmic-ray (CR) antiprotons has been provided with unprecedented accuracy by
AMS-02 on the International Space Station. Its data spans an energy range from
below 1 GeV up to 400 GeV and most of the data points contain errors below the
amazing level of 5%. The bulk of the antiproton flux is expected to be produced
by the scatterings of CR protons and helium off interstellar hydrogen and
helium atoms at rest. The modeling of these interactions, which requires the
relevant production cross sections, induces an uncertainty in the determination
of the antiproton source term that can even exceed the uncertainties in the CR
data itself. The aim of the present analysis is to determine the
uncertainty required for cross section
measurements such that the induced uncertainties on the flux are at
the same level. Our results are discussed both in the center-of-mass reference
frame, suitable for collider experiments, and in the laboratory frame, as
occurring in the Galaxy. We find that cross section data should be collected
with accuracy better that few percent with proton beams from 10 GeV to 6 TeV
and a pseudorapidity ranging from 2 to almost 8 or, alternatively, with
from 0.04 to 2 GeV and from 0.02 to 0.7. Similar considerations
hold for the He production channel. The present collection of data is far
from these requirements. Nevertheless, they could, in principle, be reached by
fixed target experiments with beam energies in the reach of CERN accelerators.Comment: 15 pages, 13 figures, matches published versio
Multi-messenger constraints to the local emission of cosmic-ray electrons
The data on the inclusive flux of cosmic positrons and electrons
() have been recently collected from GeV to tens of TeV energies by
several experiments with unprecedented precision. In addition, the Fermi-LAT
Collaboration has provided a new energy spectrum for the upper bounds on the
dipole anisotropy. This observable can bring information on the
emission from local Galactic sources, notably measured with high precision at
radio frequencies. We develop a framework in which and measured at
Earth from GeV up to tens of TeV energies have a composite origin. A dedicated
analysis is deserved to Vela YZ and Cygnus Loop Supernova Remnants (SNRs), for
which we consider two different models for the injection of . We
investigate the consistency of these models using the three physical
observables: the radio flux from Vela YZ and Cygnus Loop at all the available
frequencies, the flux from five experiments from the GeV to tens of
TeV energy, the dipole anisotropy upper limits from 50 GeV to about 1
TeV. We find that the radio flux for these nearby SNRs strongly constraints the
properties of the injection electron spectrum, partially compatible with the
looser constraints derived from the flux data. We also perform a
multi-wavelength multi-messenger analysis by fitting simultaneously the radio
flux on Vela YZ and Cygnus Loop and the flux, and checking the
outputs against the dipole anisotropy data. Remarkably, we find a
model which is compatible with all the flux data, the radio data for
Vela YZ and Cygnus Loop, and with the anisotropy upper bounds. We show the
severe constraints imposed by the most recent data on the dipole
anisotropy.Comment: 20 pages, 9 figures. Accepted for publication in the JCAP. Changes in
v3: discussion and results extended to include an evolutionary model for the
injection of cosmic-ray electrons in SNR
Production cross sections of cosmic antiprotons in the light of new data from the NA61 and LHCb experiments
The cosmic-ray flux of antiprotons is measured with high precision by the
space-borne particle spectrometers AMS-02.Its interpretation requires a correct
description of the dominant production process for antiprotons in our Galaxy,
namely, the interaction of cosmic-ray proton and helium with the interstellar
medium. In the light of new cross section measurements by the NA61 experiment
of and the first ever measurement of by the LHCb experiment, we update the
parametrization of proton-proton and proton-nucleon cross sections.We find that
the LHCb He data constrain a shape for the cross section at high energies
and show for the first time how well the rescaling from the channel
applies to a helium target. By using , He and C data we estimate the
uncertainty on the Lorentz invariant cross section for . We use these new cross sections to compute the source
term for all the production channels, considering also nuclei heavier than He
both in cosmic rays and the interstellar medium. The uncertainties on the total
source term are at the level of % and slightly increase below antiproton
energies of 5 GeV. This uncertainty is dominated by the cross section, which translates into all channels since we derive
them using the cross sections. The cross sections to calculate the source
spectra from all relevant cosmic-ray isotopes are provided in the Supplemental
Material. We finally quantify the necessity of new data on antiproton
production cross sections, and pin down the kinematic parameter space which
should be covered by future data.Comment: 16 pages, 11 figures, matches published versio
Composition of the Fermi-LAT isotropic gamma-ray background intensity: Emission from extragalactic point sources and dark matter annihilations
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