Constraints on cosmic-ray positron excess and average pulsar parameters

Grimani, C.

doi:10.1051/0004-6361:20077776

Cited by 33 publications

(44 citation statements)

References 29 publications

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“…This excess was pointed out by Moskalenko & Strong (1998) when they derived their predictions of both the secondary positron flux and the primary plus secondary electron fluxes. This led to many possible interpretations, such e.g., a potential positron injection from dark matter annihilation in the Galaxy (e.g., Baltz & Edsjö 1999) or from pulsars (e.g., Aharonian et al 1995;Boulares 1989;Grimani 2007).…”

Section: The Positron Fractionmentioning

confidence: 99%

Galactic secondary positron flux at the Earth

Delahaye

Lineros²,

Donato³

et al. 2009

A&A

218

308

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Context. Secondary positrons are produced by spallation of cosmic rays within the interstellar gas. Measurements have been typically expressed in terms of the positron fraction, which exhibits an increase above 10 GeV. Many scenarios have been proposed to explain this feature, among them some additional primary positrons originating from dark matter annihilation in the Galaxy. Aims. The PAMELA satellite has provided high quality data that has enabled high accuracy statistical analyses to be made, showing that the increase in the positron fraction extends up to about 100 GeV. It is therefore of paramount importance to constrain theoretically the expected secondary positron flux to interpret the observations in an accurate way. Methods. We focus on calculating the secondary positron flux by using and comparing different up-to-date nuclear cross-sections and by considering an independent model of cosmic ray propagation. We carefully study the origins of the theoretical uncertainties in the positron flux. Results. We find the secondary positron flux to be reproduced well by the available observations, and to have theoretical uncertainties that we quantify to be as large as about one order of magnitude. We also discuss the positron fraction issue and find that our predictions may be consistent with the data taken before PAMELA. For PAMELA data, we find that an excess is probably present after considering uncertainties in the positron flux, although its amplitude depends strongly on the assumptions made in relation to the electron flux. By fitting the current electron data, we show that when considering a soft electron spectrum, the amplitude of the excess might be far lower than usually claimed. Conclusions. We provide fresh insights that may help to explain the positron data with or without new physical model ingredients. PAMELA observations and the forthcoming AMS-02 mission will allow stronger constraints to be aplaced on the cosmic-ray transport parameters, and are likely to reduce drastically the theoretical uncertainties.

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Section: The Positron Fractionmentioning

confidence: 99%

Galactic secondary positron flux at the Earth

Delahaye

Lineros²,

Donato³

et al. 2009

A&A

218

308

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“…We use the model by Gleeson and Axford to estimate the particle energy spectra during a positive polarity epoch (continuous lines in figs.2 and 3 for protons and helium nuclei, respectively. References to data are reported in [13]). …”

Section: Galactic Cosmic-ray Proton and Helium Energy Spectra At The mentioning

confidence: 99%

“…With β and R we indicate particle velocity and rigidity, respectively. The energy spectra during a negative polarity epoch were estimated according to [13] for near-solar-maximum conditions (dashed lines in figs.2 and 3). Presently, the Sun has a negative polarity.…”

Section: Galactic Cosmic-ray Proton and Helium Energy Spectra At The mentioning

confidence: 99%

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Galactic cosmic-ray energy spectra and expected solar events at the time of future space missions

Grimani¹,

Araújo²,

Fabi³

et al. 2011

Class. Quantum Grav.

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Galactic cosmic-rays (GCRs) and solar energetic particles (SEPs) affect observations on board long-lived space missions. We developed a parameterization of proton and helium fluxes for various levels of solar modulation during opposite polarity periods. In addition to long-term variations (decades), short-term fluctuations (minutes to days) were considered as well. In particular, we focused on data from experiments carrying magnetic spectrometers in space. The shortest GCR variations we were able to study are of the order of hours. We point out that GCR variations and fluctuations are strongly energy dependent. Energy dependent is also the detector charging on board space experiments. The measurements of energy differential fluxes and their variations are needed in order to evaluate properly the performance of future space missions. We present here the projections for the GCR fluxes and solar events at the time of LISA (Laser Interferometer Space Antenna) Pathfinder (LISA-PF).

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“…Both were extensively studied in the last 60 years on Earth with neutron monitors and in space (Forbush 1954(Forbush , 1958Storini et al 1992;Beer 2000;Clem & Evenson 2004;Ferreira et al 2004;Grimani 2004Grimani , 2007Hajadas et al 2004;Grimani et al 2007;Shikaze et al 2007;Sabbah & Kudela 2011;Usoskin et al 2011Usoskin et al , 2017Laurenza et al 2012Laurenza et al , 2014.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Energy Dependence of Recurrent Galactic Cosmic-Ray Flux Depressions and of a Forbush Decrease with LISA Pathfinder

Armano

Audley

Baird

et al. 2018

ApJ

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Galactic cosmic-ray (GCR) energy spectra observed in the inner heliosphere are modulated by the solar activity, the solar polarity and structures of solar and interplanetary origin. A high counting rate particle detector (PD) aboard LISA Pathfinder, meant for subsystems diagnostics, was devoted to the measurement of GCR and solar energetic particle integral fluxes above 70 MeV n −1 up to 6500 counts s −1 . PD data were gathered with a sampling time of 15 s. Characteristics and energy dependence of GCR flux recurrent depressions and of a Forbush decrease dated 2016 August 2 are reported here. The capability of interplanetary missions, carrying PDs for instrument performance purposes, in monitoring the passage of interplanetary coronal mass ejections is also discussed.

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Constraints on cosmic-ray positron excess and average pulsar parameters

Cited by 33 publications

References 29 publications

Galactic secondary positron flux at the Earth

Galactic secondary positron flux at the Earth

Galactic cosmic-ray energy spectra and expected solar events at the time of future space missions

Characteristics and Energy Dependence of Recurrent Galactic Cosmic-Ray Flux Depressions and of a Forbush Decrease with LISA Pathfinder

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