Multiwavelength features of Fermi bubbles as signatures of a Galactic wind

Sarkar, Kartick C.; Nath, Biman B.; Sharma, Prateek

doi:10.1093/mnras/stv1806

Cited by 63 publications

(46 citation statements)

References 43 publications

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“…229,230 ); or a period of star burst activity (or steady star formation) resulting in combined winds from explosions of massive stars (star burst/star formation scenario) (e.g. 231,232 ).…”

Section: Fermi Bubblesmentioning

confidence: 99%

The origin of Galactic cosmic rays: Challenges to the standard paradigm

Gabici

Evoli

Gaggero

et al. 2019

Int. J. Mod. Phys. D

187

133

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A critical review of the standard paradigm for the origin of Galactic cosmic rays is presented. Recent measurements of local and far-away cosmic rays reveal unexpected behaviours, which challenge the commonly accepted scenario. These recent findings are discussed, together with long-standing open issues. Despite the progress made thanks to ever-improving observational techniques and theoretical investigations, at present our understanding of the origin and of the behaviour of cosmic rays remains incomplete. We believe it is still unclear whether a modification of the standard paradigm, or rather a radical change of the paradigm itself is needed in order to interpret all the available data 1 arXiv:1903.11584v2 [astro-ph.HE]

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“…229,230 ); or a period of star burst activity (or steady star formation) resulting in combined winds from explosions of massive stars (star burst/star formation scenario) (e.g. 231,232 ).…”

Section: Fermi Bubblesmentioning

confidence: 99%

The origin of Galactic cosmic rays: Challenges to the standard paradigm

Gabici

Evoli

Gaggero

et al. 2019

Int. J. Mod. Phys. D

187

133

View full text Add to dashboard Cite

show abstract

“…We note though that in reality a range of velocity profiles can provide such a uniform brightness. See for example [19]. In general, we find that for the case of a constant density ambient medium description, the present γ-ray data can be said to prefer decelerating profiles.…”

Section: Pos(icrc2017)870mentioning

confidence: 57%

A Hadronic Model of the Fermi Bubbles: Cosmic-Rays in a Galactic Breeze

Giacinti

Taylor

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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We present a self-consistent model of the Fermi Bubbles, described as a decelerating outflow of gas and non-thermal particles produced within the Galactic center region, on a ∼ 100 Myr timescale. Motivated by observations, we use an outflow with velocity of a few hundreds of km/s, which is slower than the velocities used in models describing the Bubbles as a more recent outburst. We take into account cosmic-ray (CR) energy losses due to proton-proton interactions, and calculate the resulting gamma-ray emission. Our model can reproduce both the spatial morphology and the spectra of the Bubbles, on a range of different scales. We find that CR diffusing and advecting within a breeze outflow result in an approximately flat surface brightness profile of the gamma-ray emission, as observed by Fermi satellite. Finally, we apply similar outflow profiles to larger Galactocentric radii, and investigate their effects on the CR spectrum and boron-to-carbon ratio. Hardenings can appear in the spectrum, even in cases with equal CR diffusion coefficients in the disk and halo. It is postulated that this hardening effect may relate to the observed hardening feature in the CR spectrum at a rigidity of ∼ 200 GV.

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“…We note though that in reality a range of velocity profiles can provide such a uniform brightness. See for example [40]. In general, we find that for the case of a constant density ambient medium description, the present γ-ray data can be said to prefer decelerating profiles.…”

Section: Introductionmentioning

confidence: 57%

Cosmic rays in a galactic breeze

Taylor

Giacinti

2017

Phys. Rev. D

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Motivated by the discovery of the non-thermal Fermi bubble features both below and above the Galactic plane, we investigate a scenario in which these bubbles are formed through Galactocentric outflow. Cosmic rays (CR) both diffusing and advecting within a Galactic breeze outflow, interacting with the ambient gas present, give rise to γ-ray emission, providing an approximately flat surface brightness profile of this emission, as observed. Applying the same outflow profile further out within the disk, the resultant effects on the observable CR spectral properties are determined. A hardening in the spectra due to the competition of advective and diffusive propagation within a particular energy range is noted, even in the limiting case of equal CR diffusion coefficients in the disk and halo. It is postulated that this hardening effect may relate to the observed hardening feature in the CR spectrum at a rigidity of ≈ 200 GV.

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Multiwavelength features of Fermi bubbles as signatures of a Galactic wind

Cited by 63 publications

References 43 publications

The origin of Galactic cosmic rays: Challenges to the standard paradigm

The origin of Galactic cosmic rays: Challenges to the standard paradigm

A Hadronic Model of the Fermi Bubbles: Cosmic-Rays in a Galactic Breeze

Cosmic rays in a galactic breeze

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