scholarly journals Constraining positron emission from pulsar populations with AMS-02 data

2021 ◽  
Vol 2021 (12) ◽  
pp. 014
Author(s):  
Luca Orusa ◽  
Silvia Manconi ◽  
Fiorenza Donato ◽  
Mattia Di Mauro
Keyword(s):  
Cosmic Ray ◽  
Physical Parameters ◽  
Pulsar Wind Nebulae ◽  
Positron Emission ◽  
The Galaxy ◽  
Emission Models ◽  
Pulsar Wind ◽  
Pulsar Populations ◽  
The Impact ◽  
Cosmic Ray Flux

Abstract The cosmic-ray flux of positrons is measured with high precision by the space-borne particle spectrometer AMS-02. The hypothesis that pulsar wind nebulae (PWNe) can significantly contribute to the excess of the positron (e+) cosmic-ray flux has been consolidated after the observation of a γ-ray emission at TeV energies of a few degree size around Geminga and Monogem PWNe. In this work we undertake massive simulations of galactic pulsars populations, adopting different distributions for their position in the Galaxy, intrinsic physical properties, pair emission models, in order to overcome the incompleteness of the ATNF catalog. We fit the e+ AMS-02 data together with a secondary component due to collisions of primary cosmic rays with the interstellar medium. We find that several mock galaxies have a pulsar population able to explain the observed e+ flux, typically by few, bright sources. We determine the physical parameters of the pulsars dominating the e+ flux, and assess the impact of different assumptions on radial distributions, spin-down properties, Galactic propagation scenarios and e+ emission time.

scholarly journals PeV Emission of the Crab Nebula: Constraints on the Proton Content in Pulsar Wind and Implications

2021 ◽  
Vol 922 (2) ◽  
pp. 221
Author(s):  
Ruo-Yu Liu ◽  
Xiang-Yu Wang
Keyword(s):  
Energy Content ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Ultrahigh Energy ◽  
Pulsar Wind Nebulae ◽  
Air Shower ◽  
Pulsar Wind ◽  
The Crab Nebula ◽  
Pulsar Winds ◽  
Cosmic Ray Flux

Abstract Recently, two photons from the Crab Nebula with energy of approximately 1 PeV were detected by the Large High Altitude Air Shower Observatory (LHAASO), opening an ultrahigh-energy window for studying pulsar wind nebulae (PWNe). Remarkably, the LHAASO spectrum at the highest-energy end shows a possible hardening, which could indicate the presence of a new component. A two-component scenario with a main electron component and a secondary proton component has been proposed to explain the whole spectrum of the Crab Nebula, requiring a proton energy of 1046–1047 erg remaining in the present Crab Nebula. In this paper, we study the energy content of relativistic protons in pulsar winds using the LHAASO data of the Crab Nebula, considering the effect of diffusive escape of relativistic protons. Depending on the extent of the escape of relativistic protons, the total energy of protons lost in the pulsar wind could be 10–100 times larger than that remaining in the nebula presently. We find that the current LHAASO data allow up to (10–50)% of the spindown energy of pulsars being converted into relativistic protons. The escaping protons from PWNe could make a considerable contribution to the cosmic-ray flux of 10–100 PeV. We also discuss the leptonic scenario for the possible spectral hardening at PeV energies.

scholarly journals Molecular Clouds and Star Formation at Large R

1991 ◽  
Vol 144 ◽  
pp. 121-130
Author(s):  
J. Brand ◽  
J.G.A. Wouterloot
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Density Wave ◽  
Cosmic Ray ◽  
Volume Density ◽  
Kinetic Temperature ◽  
Galactocentric Distance ◽  
The Galaxy ◽  
The Mean ◽  
Cosmic Ray Flux

In the outer Galaxy (defined here as those parts of our system with galactocentric radii R>R0) the HI gas density (Wouterloot et al., 1990), the cosmic ray flux (Bloemen et al, 1984) and the metallicity (Shaver et al., 1983) are lower than in the inner parts. Also, the effect of a spiral density wave is much reduced in the outer parts of the Galaxy due to corotation. This changing environment might be expected to have its influence on the formation of molecular clouds and on star formation within them. In fact, some differences with respect to the inner Galaxy have been found: the ratio of HI to H2 surface density is increasing from about 5 near the Sun to about 100 at R≈20kpc (Wouterloot et al., 1990). Because of the “flaring” of the gaseous disk, the scale height of both the atomic and the molecular gas increases by about a factor of 3 between R0 and 2R0 (Wouterloot et al., 1990), so the mean volume density of both constituents decreases even more rapidly than their surface densities. The size of HII regions decreases significantly with increasing galactocentric distance (Fich and Blitz, 1984), probably due to the fact that outer Galaxy clouds are less massive (see section 3.3), and therefore form fewer O-type stars than their inner Galaxy counter parts. There are indications that the cloud kinetic temperature is lower by a few degrees (Mead and Kutner, 1988), although it is not clear to what extent this is caused by beam dilution.

Processes of MHD-wave radiation and of cosmic ray flux focusing in the Galaxy

1994 ◽  
Vol T52 ◽  
pp. 106-109
Author(s):  
V A Dogiel ◽  
A V Gurevich ◽  
K P Zybin
Keyword(s):  
Cosmic Ray ◽  
Wave Radiation ◽  
The Galaxy ◽  
Cosmic Ray Flux

scholarly journals GeV Observations of the Extended Pulsar Wind Nebulae Constrain the Pulsar Interpretations of the Cosmic-Ray Positron Excess

2019 ◽  
Vol 878 (2) ◽  
pp. 104 ◽  
Author(s):  
Shao-Qiang Xi ◽  
Ruo-Yu Liu ◽  
Zhi-Qiu Huang ◽  
Kun Fang ◽  
Xiang-Yu Wang
Keyword(s):  
Cosmic Ray ◽  
Pulsar Wind Nebulae ◽  
Pulsar Wind

scholarly journals TeV Cosmic Ray Anisotropy and the Heliospheric Magnetic Field

2014 ◽  
Vol 1 ◽  
pp. 65-71 ◽  
Author(s):  
P. Desiati ◽  
A. Lazarian
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Particle Distribution ◽  
Sudden Change ◽  
Cosmic Ray ◽  
Arrival Direction ◽  
Energy Dependency ◽  
The Galaxy ◽  
Different Characteristics ◽  
Cosmic Ray Flux

Abstract. Cosmic rays are observed to possess a small non uniform distribution in arrival direction. Such anisotropy appears to have a roughly consistent topology between tens of GeV and hundreds of TeV, with a smooth energy dependency on phase and amplitude. Above a few hundreds of TeV a sudden change in the topology of the anisotropy is observed. The distribution of cosmic ray sources in the Milky Way is expected to inject anisotropy on the cosmic ray flux. The nearest and most recent sources, in particular, are expected to contribute more significantly than others. Moreover the interstellar medium is expected to have different characteristics throughout the Galaxy, with different turbulent properties and injection scales. Propagation effects in the interstellar magnetic field can shape the cosmic ray particle distribution as well. In particular, in the 1–10 TeV energy range, they have a gyroradius comparable to the size of the Heliosphere, assuming a typical interstellar magnetic field strength of 3 μG. Therefore they are expected to be strongly affected by the Heliosphere in a manner ordered by the direction of the local interstellar magnetic field and of the heliotail. In this paper we discuss on the possibility that TeV cosmic rays arrival distribution might be significantly redistributed as they propagate through the Heliosphere.

scholarly journals The distribution of cosmic-ray ionization rates in diffuse molecular clouds as probed by H 3 +

2012 ◽  
Vol 370 (1978) ◽  
pp. 5142-5150 ◽  
Author(s):  
Nick Indriolo
Keyword(s):  
Molecular Clouds ◽  
Cosmic Ray ◽  
Ionization Rate ◽  
Line Of Sight ◽  
Interstellar Clouds ◽  
Upper Limits ◽  
The Galaxy ◽  
Cosmic Ray Flux ◽  
Made In ◽  
Ionization Rates

Owing to its simple chemistry, H is widely regarded as the most reliable tracer of the cosmic-ray ionization rate in diffuse interstellar clouds. At present, H observations have been made in over 50 sight lines that probe the diffuse interstellar medium (ISM) throughout the Galaxy. This small survey presents the opportunity to investigate the distribution of cosmic-ray ionization rates in the ISM, as well as any correlations between the ionization rate and line-of-sight properties. Some of the highest inferred ionization rates are about 25 times larger than the lowest upper limits, suggesting variations in the underlying low-energy cosmic-ray flux across the Galaxy. Most likely, such variations are caused predominantly by the distance between an observed cloud and the nearest site of particle acceleration.

scholarly journals Pulsar Wind Nebulae inside Supernova Remnants as Cosmic-Ray PeVatrons

2018 ◽  
Vol 478 (1) ◽  
pp. 926-931 ◽  
Author(s):  
Yutaka Ohira ◽  
Shota Kisaka ◽  
Ryo Yamazaki
Keyword(s):  
Supernova Remnants ◽  
Cosmic Ray ◽  
Pulsar Wind Nebulae ◽  
Pulsar Wind

scholarly journals Pulsar Wind Nebulae with Bow Shocks: Non-thermal Radiation and Cosmic Ray Leptons

2017 ◽  
Vol 207 (1-4) ◽  
pp. 235-290 ◽  
Author(s):  
A. M. Bykov ◽  
E. Amato ◽  
A. E. Petrov ◽  
A. M. Krassilchtchikov ◽  
K. P. Levenfish
Keyword(s):  
Thermal Radiation ◽  
Cosmic Ray ◽  
Pulsar Wind Nebulae ◽  
Bow Shocks ◽  
Pulsar Wind

The Extragalactic Flux of Cosmic Rays

1996 ◽  
Vol 13 (2) ◽  
pp. 121-126 ◽  
Author(s):  
R. W. Clay ◽  
A. G. K. Smith
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Power Law ◽  
Cosmic Ray ◽  
Static Magnetic Fields ◽  
Remarkable Similarity ◽  
Flux Change ◽  
The Galaxy ◽  
Energy Perturbation ◽  
Cosmic Ray Flux

AbstractThe propagation of extragalactic particles within our Galaxy has been modelled. The flux of such particles is below the observed cosmic ray flux at most energies when their power-law spectrum is extrapolated back from the highest energies. Also, we expect that the propagation of extragalactic particles through static magnetic fields in the Galaxy will not result in a flux change to match the flux of particles measured here within the Galaxy. However, if we were to consider the observed cosmic rays to be of Galactic origin, there would be a remarkable similarity between the required Galactic injection flux and the extrapolated extragalactic flux. We consider here whether the scattering of extragalactic particles in the Galaxy together with an associated energy perturbation might be sufficient for the extragalactic beam to result in the production of ‘Galactic’ particles and, hence, essentially all of the observed cosmic rays. This appears to be possible.

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