Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: The case of Vela-X

Torre, S. Della; Gervasi, M.; Rancoita, P.G.; Rozza, D.; Treves, A.

doi:10.1016/j.jheap.2015.08.001

Cited by 22 publications

(16 citation statements)

References 68 publications

(92 reference statements)

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“…The all-electron spectrum includes twice the positron excess that accounts for both extra electron and positron components. The inclusion of the extra electron and positron components in equal amounts improves the agreement with the AMS-02 data (Della Torre et al 2015). A possible origin of this excess will be discussed in a forthcoming paper devoted to the positron LIS.…”

Section: Electron Lismentioning

confidence: 62%

HelMod in the Works: From Direct Observations to the Local Interstellar Spectrum of Cosmic-Ray Electrons

Boschini

Torre

Gervasi

et al. 2018

ApJ

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The local interstellar spectrum (LIS) of cosmic-ray (CR) electrons for the energy range 1 MeV to 1 TeV is derived using the most recent experimental results combined with the state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. Two propagation packages, GALPROP and HELMOD, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HELMOD, which provides the modulated spectra for specific time periods of the selected experiments for model-data comparison. The optimized HelMod parameters are then used to adjust GALPROP parameters to predict a refined LIS with the procedure repeated subject to a convergence criterion. The parameter optimization uses an extensive data set of proton spectra from 1997 to 2015. The proposed CR electron LIS accommodates both the low-energy interstellar spectra measured by Voyager 1 as well as the high-energy observations by PAMELA and AMS-02 that are made deep in the heliosphere; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The interstellar and heliospheric propagation parameters derived in this study agree well with our earlier results for CR protons, helium nuclei, and anti-protons propagation and LIS obtained in the same framework.

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Section: Electron Lismentioning

confidence: 62%

HelMod in the Works: From Direct Observations to the Local Interstellar Spectrum of Cosmic-Ray Electrons

Boschini

Torre

Gervasi

et al. 2018

ApJ

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“…Positrons that contribute to the well-known 'positron excess' above 10 GeV are considered to originate from local sources 5 (e.g. Mertsch & Sarkar 2014; Di Mauro et al 2016;Della Torre et al 2015). These sources are supposed to produce also the same amount of electrons.…”

Section: Baseline Modelsmentioning

confidence: 99%

Imprints of cosmic rays in multifrequency observations of the interstellar emission

Orlando

2017

Monthly Notices of the Royal Astronomical Society

101

147

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Ever since the discovery of Cosmic Rays (CRs), significant advancements have been made in modeling their propagation in the Galaxy and in the Heliosphere. However, propagation models suffer from degeneracy of many parameters. To complicate the picture the precision of recent data have started challenging existing models.To tackle these issues we use available multifrequency observations of the interstellar emission from radio to gamma rays, together with direct CR measurements, to study local interstellar spectra (LIS) and propagation models. As a result, the electron LIS is characterized without any assumption on solar modulation, and favorite propagation models are put forward. More precisely, our analysis leads to the following main conclusions: (1) the electron injection spectrum needs at least a break below a few GeV; (2) even though consistent with direct CR measurements, propagation models producing a LIS with large all-electron density from a few hundreds of MeV to a few GeV are disfavored by both radio and gamma-ray observations; (3) the usual assumption that direct CR measurements, after accounting for solar modulation, are representative of the proton LIS in our ∼1 kpc region is challenged by the observed local gamma-ray HI emissivity. We provide the resulting proton LIS, all-electron LIS, and propagation parameters, based on synchrotron, gamma-ray, and direct CR data. A plain diffusion model and a tentative diffusive-reacceleration model are put forward. The various models are investigated in the inner-Galaxy region in X-rays and gamma rays. Predictions of the interstellar emission for future gamma-ray instruments (e-ASTROGAM and AMEGO) are derived.

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“…where η is the injection efficiency, W 0 is the pulsar energy output, t 0 is the typical pulsar decay timescale and t p is the pulsar lifetime [58,[98][99][100]]. If we take as fiducial values, η = 0.1, W 0 = 10 50 erg, t 0 = 1 kyr and assume t p ≈ t 0 we obtain a power contribution from pulsars of…”

Section: Cosmic-ray Electron Powermentioning

confidence: 99%

Exploring a cosmic-ray origin of the multiwavelength emission in M31

2019

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A recent detection of spatially extended gamma-ray emission in the central region of the Andromeda galaxy (M31) has led to several possible explanations being put forth, including dark matter annihilation and millisecond pulsars. Another possibility is that the emission in M31 can be accounted for with a purely astrophysical cosmic-ray (CR) scenario. This scenario would lead to a rich multi-wavelength emission that can, in turn, be used to test it. Relativistic cosmic-ray electrons (CRe) in magnetic fields produce radio emission through synchrotron radiation, while X-rays and gamma rays are produced through inverse Compton scattering. Additionally, collisions of primary cosmic-ray protons (CRp) in the interstellar medium produce charged and neutral pions that then decay into secondary CRe (detectable through radiative processes) and gamma-rays. Here, we explore the viability of a CR origin for multi-wavelength emission in M31, taking into consideration three scenarios: a CR scenario dominated by primary CRe, one dominated by CRp and the resulting secondary CRe and gamma rays from neutral pion decay, and a final case in which both of these components exist simultaneously. We find that the multi-component model is the most promising, and is able to fit the multi-wavelength spectrum for a variety of astrophysical parameters consistent with previous studies of M31 and of cosmic-ray physics. However, the CR power injection implied by our models exceeds the estimated CR power injection from typical astrophysical cosmic-ray sources such as supernovae.

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Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: The case of Vela-X

Cited by 22 publications

References 68 publications

HelMod in the Works: From Direct Observations to the Local Interstellar Spectrum of Cosmic-Ray Electrons

HelMod in the Works: From Direct Observations to the Local Interstellar Spectrum of Cosmic-Ray Electrons

Imprints of cosmic rays in multifrequency observations of the interstellar emission

Exploring a cosmic-ray origin of the multiwavelength emission in M31

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