GALPROP WebRun: An internet-based service for calculating galactic cosmic ray propagation and associated photon emissions

Vladimirov, Andrey; Digel, S. W.; Jóhannesson, G.; Michelson, P. F.; Moskalenko, I. V.; Nolan, P. L.; Orlando, E.; Porter, T. A.; Strong, A. W.

doi:10.1016/j.cpc.2011.01.017

Cited by 251 publications

(228 citation statements)

References 31 publications

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“…For the Galactic background, we have used three different templates, S S Z 4 R 20 T 150 C 5 , S L Z 6 R 20 T ∞ C 5 , S Y Z 6 R 30 T 150 C 2 , based on the GALPROP code (Vladimirov et al 2011). These templates were also used by the Fermi/LAT collaboration for the development and testing of the standard template 4 .…”

Section: Appendix A: the Analysis Of The Lowest-energy Datamentioning

confidence: 99%

“…The standard Fermi/LAT template for the Galactic diffuse background is phenomenologically based (Acero et al 2016) on a linear combination of: -inverse Compton (IC) intensity template predicted by the GAL-PROP code (Vladimirov et al 2011) for its S Y Z 6 R 30 T 150 C 2 model; -templates for the H column density (defined in 9 Galactocentric annuli), -templates accounting for the emission from large-scale diffuse structures (Loop I, Fermi Bubbles, North Polar Spur). These components in a linear combination with: -an isotropic template, accounting for the unresolved extragalactic γ-ray sources and for residual cosmic-ray contamination in the photon data; -templates of the Solar, Lunar and Earth limb emissions; -templates for point-like and extended sources from the 3FGL catalogue; were fitted to the all-sky survey data, which allowed the LAT team to determine the coefficients of the above described combination.…”

Section: Appendix A: the Analysis Of The Lowest-energy Datamentioning

confidence: 99%

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High-energy gamma-rays from Cyg X-1

Zdziarski

Malyshev

Chernyakova

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We have obtained a firm detection of Cyg X-1 during its hard and intermediate spectral states in the energy range of 40 MeV-60 GeV based on observations by the Fermi Large Area Telescope, confirming the independent results at ≥60MeV of a previous work. The detection significance is 8σ in the 0.1-10 GeV range. In the soft state, we have found only upper limits on the emission at energies 0.1 MeV. However, we have found emission with a very soft spectrum in the 40-80 MeV range, not detected previously. This is likely to represent the high-energy cutoff of the high-energy power-law tail observed in the soft state. Similarly, we have detected a γ-ray soft excess in the hard state, which appears to be of similar origin. We have also confirmed the presence of an orbital modulation of the detected emission in the hard state, expected if the γ-rays are from Compton upscattering of stellar blackbody photons. However, the observed modulation is significantly weaker than that predicted if the blackbody upscattering were the dominant source of γ-rays. This argues for a significant contribution from γ-rays produced by the synchrotron-self-Compton process. We have found that such strong contribution is possible if the jet is strongly clumped. We reproduce the observed hardstate average broad-band spectrum using a self-consistent jet model, taking into account all the relevant emission processes, e ± pair absorption, and clumping. This model also reproduces the amplitude of the observed orbital modulation.

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Section: Appendix A: the Analysis Of The Lowest-energy Datamentioning

confidence: 99%

Section: Appendix A: the Analysis Of The Lowest-energy Datamentioning

confidence: 99%

High-energy gamma-rays from Cyg X-1

Zdziarski

Malyshev

Chernyakova

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…We do this by repeating the analysis using several templates for Galactic diffuse emission and several sets of point sources. For the Galactic diffuse background, we consider gll_iem_v05_rev1.fits, the most recent template, recommended Fermi/LAT collaboration for the analysis gll_iem_v05.fits, which is an earlier version of the template, and LRYusifovXCO4z6R30_Ts150_mag2 5 , a template based on the prediction from GALPROP code (Vladimirov et al 2011). As a radical alternative to these models, we also consider a model in which we replace the background in the 3 • × 1 • box around the GC in gll_iem_v05_rev1.fits template with a rectangle of uniform surface brightness.…”

Section: Fermi/lat Spectral Analysismentioning

confidence: 99%

Leptonic origin of the 100 MeVγ-ray emission from the Galactic centre

Malyshev

Chernyakova

Neronov

et al. 2015

A&A

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Context. The Galactic centre is a bright γ-ray source with the GeV−TeV band spectrum composed of two distinct components in the 1−10 GeV and 1−10 TeV energy ranges. The nature of these two components is not clearly understood. Aims. We investigate the γ-ray properties of the Galactic centre to clarify the origin of the observed emission. Methods. We report imaging, spectral, and timing analysis of data from 74 months of observations of the Galactic centre by Fermi/LAT γ-ray telescope complemented by sub-MeV data from approximately ten years of INTEGRAL/PICsIT observations. Results. We find that the Galactic centre is spatially consistent with the point source in the GeV band. The tightest 3σ upper limit on its radius is 0.13 • in the 10−300 GeV energy band. The spectrum of the source in the 100 MeV energy range does not have a characteristic turnover that would point to the pion decay origin of the signal. Instead, the source spectrum is consistent with a model of inverse Compton scattering by high-energy electrons. In this a model, the GeV bump in the spectrum originates from an episode of injection of high-energy particles, which happened ∼300 years ago. This injection episode coincides with the known activity episode of the Galactic centre region, previously identified using X-ray observations. The hadronic model of source activity could be still compatible with the data if bremsstrahlung emission from high-energy electrons was present in addition to pion decay emission.

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“…We compared the results to the expected ionisation rate by cosmic rays (see Sect. 4.2) and chose to use the CR distribution at 100 MeV/nucleon given by the GALPROP code (reacceleration model, http://galprop.stanford.edu/, Vladimirov et al 2011). All elements lighter than copper are considered (Z ≤ 29).…”

Section: The Interstellar Cosmic Ray Fluxmentioning

confidence: 99%

Ion irradiation of carbonaceous interstellar analogues

Godard

Féraud

Chabot

et al. 2011

A&A

108

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Context. A 3.4 μm absorption band (around 2900 cm −1 ), assigned to aliphatic C-H stretching modes of hydrogenated amorphous carbons (a-C:H), is widely observed in the diffuse interstellar medium, but disappears or is modified in dense clouds. This spectral difference between different phases of the interstellar medium reflects the processing of dust in different environments. Cosmic ray bombardment is one of the interstellar processes that make carbonaceous dust evolve. Aims. We investigate the effects of cosmic rays on the interstellar 3.4 μm absorption band carriers. Methods. Samples of carbonaceous interstellar analogues (a-C:H and soot) were irradiated at room temperature by swift ions with energy in the MeV range (from 0.2 to 160 MeV). The dehydrogenation and chemical bonding modifications that occurred during irradiation were studied with IR spectroscopy. Results. For all samples and all ions/energies used, we observed a decrease of the aliphatic C-H absorption bands intensity with the ion fluence. This evolution agrees with a model that describes the hydrogen loss as caused by the molecular recombination of two free H atoms created by the breaking of C-H bonds by the impinging ions. The corresponding destruction cross section and asymptotic hydrogen content are obtained for each experiment and their behaviour over a large range of ion stopping powers are inferred. Using elemental abundances and energy distributions of galactic cosmic rays, we investigated the implications of these results in different astrophysical environments. The results are compared to the processing by UV photons and H atoms in different regions of the interstellar medium. Conclusions. The destruction of aliphatic C-H bonds by cosmic rays occurs in characteristic times of a few 10 8 years, and it appears that even at longer time scales, cosmic rays alone cannot explain the observed disappearance of this spectral signature in dense regions. In diffuse interstellar medium, the formation by atomic hydrogen prevails over the destruction by UV photons (destruction by cosmic rays is negligible in these regions). Only the cosmic rays can penetrate into dense clouds and process the corresponding dust. However, they are not efficient enough to completely dehydrogenate the 3.4 μm carriers during the cloud lifetime. This interstellar component should be destroyed in interfaces between diffuse and dense interstellar regions where photons still penetrate but hydrogen is in molecular form.

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GALPROP WebRun: An internet-based service for calculating galactic cosmic ray propagation and associated photon emissions

Cited by 251 publications

References 31 publications

High-energy gamma-rays from Cyg X-1

High-energy gamma-rays from Cyg X-1

Leptonic origin of the 100 MeVγ-ray emission from the Galactic centre

Ion irradiation of carbonaceous interstellar analogues

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