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It is widely accepted that cosmic rays (CRs) up to at least PeV energies are Galactic in origin. Accelerated particles are injected into the interstellar medium where they propagate to the farthest reaches of the Milky Way, including a…

We report the analysis of the Fermi-Large Area Telescope data from six nearby giant molecular clouds (MCs) belonging to the Gould Belt and the Aquila Rift regions. The high statistical {\gamma}-ray spectra above 3 GeV well described by…

High Energy Astrophysical Phenomena · Physics 2020-09-21 Vardan Baghmanyan , Giada Peron , Sabrina Casanova , Felix Aharonian , Roberta Zanin

We report the results of our study of the energy spectra and absolute fluxes of cosmic rays (CRs) in the Local Galaxy based on a five-year $\gamma$-ray observation with the Fermi Large Area Telescope (LAT) of eight nearby giant molecular…

High Energy Astrophysical Phenomena · Physics 2014-07-03 Rui-zhi Yang , Emma de Oña Wilhelmi , Felix Aharonian

High energy $\gamma$ rays from Giant Molecular Clouds (GMCs) carry direct information about the spatial and energy distributions of Galactic Cosmic Rays (CRs). The recently released catalogs of GMCs contain sufficiently massive clouds to be…

High Energy Astrophysical Phenomena · Physics 2020-04-22 Felix Aharonian , Giada Peron , Ruizhi Yang , Sabrina Casanova , Roberta Zanin

We investigate the diffusion of cosmic rays (CR) close to their sources. Propagating individual CRs in purely isotropic turbulent magnetic fields with maximal scale of spatial variations Lmax, we find that CRs diffuse anisotropically at…

High Energy Astrophysical Phenomena · Physics 2012-06-29 G. Giacinti , M. Kachelriess , D. V. Semikoz

The spectrum and morphology of the diffuse Galactic gamma-ray emission carries valuable information on cosmic ray (CR) propagation. Recent results obtained by analyzing Fermi-LAT data accumulated over seven years of observation show a…

High Energy Astrophysical Phenomena · Physics 2016-08-05 S. Recchia , P. Blasi , G. Morlino

The nearby Orion-Eridanus superbubble, which was blown by multiple supernovae several Myr ago, has likely produced cosmic rays. Its turbulent medium, still energised by massive stars, can impact cosmic-ray transport locally. The gamma rays…

High Energy Astrophysical Phenomena · Physics 2020-03-18 T. Joubaud , I. A. Grenier , J. -M. Casandjian , T. Tolksdorf , R. Schlickeiser

The propagation of TeV-PeV cosmic rays (CR) in our Galaxy can be described as a diffusive process. We discuss here two effects, with important observational consequences, that cannot be predicted by the diffusion approximation in its usual…

High Energy Astrophysical Phenomena · Physics 2014-12-01 G. Giacinti

We study the capability of low-energy cosmic rays (CR) to penetrate into diffuse clouds when they move from the hot ionized plasma to a cool cloud embedded in that plasma. The spectrum of CR inside a cloud can be remarkably different from…

High Energy Astrophysical Phenomena · Physics 2014-10-30 Giovanni Morlino , Stefano Gabici

We show that the well-known discrepancy between the radial dependence of the Galactic cosmic ray (CR) nucleon distribution, as inferred most recently from EGRET observations of diffuse gamma-rays above 100 MeV, and of the most likely CR…

Astrophysics · Physics 2009-11-07 D. Breitschwerdt , V. A. Dogiel , H. J. Voelk

Cosmic-ray (CR) sources temporarily enhance the relativistic particle density in their vicinity over the background distribution accumulated from the Galaxy-wide past injection activity and propagation. If individual sources are close…

High Energy Astrophysical Phenomena · Physics 2021-08-18 Guðlaugur Jóhannesson , Troy A. Porter

We present a novel interpretation of the $\gamma$-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8…

High Energy Astrophysical Phenomena · Physics 2017-07-26 D. Gaggero , D. Grasso , A. Marinelli , M. Taoso , A. Urbano

One of the unsolved problems in cosmic ray (CR) physics is the small radial gradient of the gamma-ray intensity compared to the inferred CR source distribution in the Galactic disk. In diffusive CR propagation models the most natural…

Astrophysics · Physics 2007-05-23 D. Breitschwerdt , V. Dogiel , H. J. V"olk

We reported the gamma-ray observation towards the giant molecular cloud Polaris Flare. Together with the dust column density map, we derived the cosmic ray density and spectrum in this cloud. Compared with the CR measured locally, the CR…

High Energy Astrophysical Phenomena · Physics 2021-12-08 Zhi-wei Cui , Rui-zhi Yang , Bing Liu

In this paper, we analyzed 12 years of Fermi LAT gamma-ray data towards three nearby giant molecular clouds (GMCs), i.e., R~CrA, Chamaeleon, and Lupus. We calibrated the gas column density of these regions by using the Planck dust opacity…

High Energy Astrophysical Phenomena · Physics 2023-04-28 Jiahao Liu , Bing Liu , Ruizhi Yang

Cosmic rays (CRs) with energies $\ll$ TeV comprise a significant component of the interstellar medium (ISM). Major uncertainties in CR behavior on observable scales (much larger than CR gyroradii) stem from how magnetic fluctuations scatter…

High Energy Astrophysical Phenomena · Physics 2024-01-24 Iryna S. Butsky , Philip F. Hopkins , Philipp Kempski , Sam B. Ponnada , Eliot Quataert , Jonathan Squire

Cosmic rays up to at least PeV energies are usually described in the framework of an elementary scenario that involves acceleration by objects that are located in the disk of the Milky Way, such as supernova remnants or massive star-forming…

High Energy Astrophysical Phenomena · Physics 2019-08-14 L. Tibaldo , S. W. Digel

The Fermi-LAT data accumulated over 7 years of {\gamma}-ray observations, together with the high resolution gas (CO & HI) and the dust opacity maps, are used to study the emissivity of {\gamma}-rays induced by interactions of cosmic rays…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Rui-zhi Yang , Felix Aharonian , Carmelo Evoli

The standard approach to cosmic-ray (CR) propagation in the Galaxy is based on the assumption that local transport properties can be extrapolated to the whole CR confining volume. Such models tend to underestimate the gamma-ray flux above…

High Energy Astrophysical Phenomena · Physics 2015-05-06 Daniele Gaggero , Alfredo Urbano , Mauro Valli , Piero Ullio

Most of the diffuse Galactic GeV gamma-ray emission is produced via collisions of cosmic ray (CR) protons with ISM protons. As such the observed spectra of the gamma-rays and the CRs should be strongly linked. Recent observations of…

High Energy Astrophysical Phenomena · Physics 2017-02-01 Lara Nava , David Benyamin , Tsvi Piran , Nir J. Shaviv
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