scholarly journals Cosmic rays: interstellar gamma-ray and radio emission

2013 ◽  
Vol 239-240 ◽  
pp. 64-69 ◽  
Author(s):  
Elena Orlando ◽  
Andrew Strong
Keyword(s):  
Cosmic Rays ◽  
Radio Emission ◽  
Gamma Ray

scholarly journals Cosmic rays and magnetic fields in the core and halo of the starburst M82: implications for galactic wind physics

2020 ◽  
Vol 494 (2) ◽  
pp. 2679-2705 ◽  
Author(s):  
Benjamin J Buckman ◽  
Tim Linden ◽  
Todd A Thompson
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Large Scale ◽  
Gamma Ray ◽  
Minor Axis ◽  
Physical Parameters ◽  
Gas Density ◽  
Star Forming

ABSTRACT Cosmic rays (CRs) and magnetic fields may be dynamically important in driving large-scale galactic outflows from rapidly star-forming galaxies. We construct two-dimensional axisymmetric models of the local starburst and superwind galaxy M82 using the CR propagation code galprop. Using prescribed gas density and magnetic field distributions, wind profiles, CR injection rates, and stellar radiation fields, we simultaneously fit both the integrated gamma-ray emission and the spatially resolved multifrequency radio emission extended along M82’s minor axis. We explore the resulting constraints on the gas density, magnetic field strength, CR energy density, and the assumed CR advection profile. In accord with earlier one-zone studies, we generically find low central CR pressures, strong secondary electron/positron production, and an important role for relativistic bremsstrahlung losses in shaping the synchrotron spectrum. We find that the relatively low central CR density produces CR pressure gradients that are weak compared to gravity, strongly limiting the role of CRs in driving M82’s fast and mass-loaded galactic outflow. Our models require strong magnetic fields and advection speeds of the order of ∼1000 km s−1 on kpc scales along the minor axis in order to reproduce the extended radio emission. Degeneracies between the controlling physical parameters of the model and caveats to these findings are discussed.

scholarly journals Starburst galaxies strike back: a multi-messenger analysis with Fermi-LAT and IceCube data

2021 ◽  
Vol 503 (3) ◽  
pp. 4032-4049
Author(s):  
Antonio Ambrosone ◽  
Marco Chianese ◽  
Damiano F G Fiorillo ◽  
Antonio Marinelli ◽  
Gennaro Miele ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Gamma Ray ◽  
Neutrino Flux ◽  
Data Interpretation ◽  
Realistic Model ◽  
High Energy ◽  
Starburst Galaxies ◽  
Neutrino Factory ◽  
High Energy Cosmic Rays ◽  
Astrophysical Objects

ABSTRACT Starburst galaxies, which are known as ‘reservoirs’ of high-energy cosmic-rays, can represent an important high-energy neutrino ‘factory’ contributing to the diffuse neutrino flux observed by IceCube. In this paper, we revisit the constraints affecting the neutrino and gamma-ray hadronuclear emissions from this class of astrophysical objects. In particular, we go beyond the standard prototype-based approach leading to a simple power-law neutrino flux, and investigate a more realistic model based on a data-driven blending of spectral indexes, thereby capturing the observed changes in the properties of individual emitters. We then perform a multi-messenger analysis considering the extragalactic gamma-ray background (EGB) measured by Fermi-LAT and different IceCube data samples: the 7.5-yr high-energy starting events (HESE) and the 6-yr high-energy cascade data. Along with starburst galaxies, we take into account the contributions from blazars and radio galaxies as well as the secondary gamma-rays from electromagnetic cascades. Remarkably, we find that, differently from the highly-constrained prototype scenario, the spectral index blending allows starburst galaxies to account for up to $40{{\ \rm per\ cent}}$ of the HESE events at $95.4{{\ \rm per\ cent}}$ CL, while satisfying the limit on the non-blazar EGB component. Moreover, values of $\mathcal {O}(100\, \mathrm{PeV})$ for the maximal energy of accelerated cosmic-rays by supernovae remnants inside the starburst are disfavoured in our scenario. In broad terms, our analysis points out that a better modelling of astrophysical sources could alleviate the tension between neutrino and gamma-ray data interpretation.

GAMMA-RAY BURSTS AS VHE-UHE SOURCES

2008 ◽  
Vol 17 (09) ◽  
pp. 1319-1332
Author(s):  
PETER MÉSZÁROS
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Lower Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Model Parameters ◽  
Fundamental Interaction ◽  
Acceleration Mechanism ◽  
Inverse Compton ◽  
Tev Gamma Rays

Gamma-ray bursts are capable of accelerating cosmic rays up to GZK energies Ep ~ 1020 eV, which can lead to a flux at Earth comparable to that observed by large EAS arrays such as Auger. The semi-relativistic outflows inferred in GRB-related hypernovae are also likely sources of somewhat lower energy cosmic rays. Leptonic processes, such as synchrotron and inverse Compton, as well as hadronic processes, can lead to GeV-TeV gamma-rays measurable by GLAST, AGILE, or ACTs, providing useful probes of the burst physics and model parameters. Photo-meson interactions also produce neutrinos at energies ranging from sub-TeV to EeV, which will be probed with forthcoming experiments such as IceCube, ANITA and KM3NeT. This would provide information about the fundamental interaction physics, the acceleration mechanism, the nature of the sources and their environment.

Gamma-Ray Bursts as Probes of the Universe

2011 ◽  
Author(s):  
Joshua S. Bloom
Keyword(s):  
Star Formation ◽  
Cosmic Rays ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Ongoing Study ◽  
Observable Universe ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

This chapter focuses on how gamma-ray bursts (GRBs) are emerging as unique tools in the study of broad areas of astronomy and physics by virtue of their special properties. The unassailable fact about GRBs that makes them such great probes is that they are fantastically bright and so can be seen to the farthest reaches of the observable Universe. In parallel with the ongoing study of GRB events and progenitors, new lines of inquiry have burgeoned: using GRBs as unique probes of the Universe in ways that are almost completely divorced from the nature of GRBs themselves. Topics discussed include studies of gas, dust, and galaxies; the history of star formation; measuring reionization and the first objects in the universe; neutrinos, gravitational waves, and cosmic rays; quantum gravity and the expansion of the universe; and the future of GRBs.

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