scholarly journals Fermi-LAT Detection of Extended Gamma-Ray Emission in the Vicinity of SNR G045.7-00.4: Evidence of Escaping Cosmic Rays Interacting with the Surrounding Molecular Clouds

2021 ◽  
Vol 923 (1) ◽  
pp. 106
Author(s):  
Hai-Ming Zhang ◽  
Ruo-Yu Liu ◽  
Yang Su ◽  
Hui Zhu ◽  
Shao-Qiang Xi ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Supernova Remnant ◽  
Milky Way ◽  
Gamma Ray ◽  
Molecular Gas ◽  
Western Boundary ◽  
Large Area ◽  
Gamma Ray Emission

Abstract We present an analysis of Fermi Large Area Telescope data of the gamma-ray emission in the vicinity of a radio supernova remnant (SNR), G045.7-00.4. To study the origin of the gamma-ray emission, we also make use of the CO survey data of Milky Way Imaging Scroll Painting to study the massive molecular gas complex that surrounds the SNR. The whole size of the gigaelectronvolt emission is significantly larger than that of the radio morphology. Above 3 GeV, the gigaelectronvolt emission is resolved into two sources: one is spatially consistent with the position of the SNR with a size comparable to that of the radio emission, and the other is located outside of the western boundary of the SNR and spatially coincident with the densest region of the surrounding molecular cloud. We suggest that the gigaelectronvolt emission of the western source may arise from cosmic rays (CRs) that have escaped the SNR and illuminated the surrounding molecular cloud. We find that the gamma-ray spectra of the western source can be consistently explained by this scenario with a total energy of ∼1050 erg in escaping CRs assuming the escape is isotropic.

scholarly journals Acceleration of cosmic rays and gamma-ray emission from supernova remnant/molecular cloud associations

2015 ◽  
Vol 105 ◽  
pp. 02001 ◽  
Author(s):  
Stefano Gabici ◽  
Julian Krause ◽  
Giovanni Morlino ◽  
Lara Nava
Keyword(s):  
Cosmic Rays ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
Gamma Ray Emission

scholarly journals Connecting the ISM to TeV PWNe and PWN candidates

2019 ◽  
Vol 36 ◽  
Author(s):  
F. J. Voisin ◽  
G. P. Rowell ◽  
M. G. Burton ◽  
Y. Fukui ◽  
H. Sano ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Molecular Gas ◽  
Pulsar Wind Nebulae ◽  
Density Estimates ◽  
Pulsar Wind

AbstractWe investigate the interstellar medium towards seven TeV gamma-ray sources thought to be pulsar wind nebulae using Mopra molecular line observations at 7 mm [CS(1–0), SiO(1–0, v = 0)], Nanten CO(1–0) data and the Southern Galactic Plane Survey/GASS Hisurvey. We have discovered several dense molecular clouds co-located to these TeV gamma-ray sources, which allows us to search for cosmic rays coming from progenitor SNRs or, potentially, from pulsar wind nebulae. We notably found SiO(1–0, v = 0) emission towards HESS J1809–193, highlighting possible interaction between the adjacent supernova remnant SNR G011.0–0.0 and the molecular cloud atd∼ 3.7 kpc. Using morphological features, and comparative studies of our column densities with those obtained from X-ray measurements, we claim a distanced∼ 8.6 − 9.7kpc for SNR G292.2–00.5,d∼ 3.5 − 5.6 kpc for PSR J1418–6058 andd∼ 1.5 kpc for the new SNR candidate found towards HESS J1303–631. From our mass and density estimates of selected molecular clouds, we discuss signatures of hadronic/leptonic components from pulsar wind nebulae and their progenitor SNRs. Interestingly, the molecular gas, which overlaps HESS J1026–582 atd∼ 5 kpc, may support a hadronic origin. We find however that this scenario requires an undetected cosmic-ray accelerator to be located atd< 10 pc from the molecular cloud. For HESS J1809–193, the cosmic rays which have escaped SNR G011.0–0.0 could contribute to the TeV gamma-ray emission. Finally, from the hypothesis that at most 20% the pulsar spin down power could be converted into CRs, we find that among the studied pulsar wind nebulae, only those from PSR J1809–1917 could potentially contribute to the TeV emission.

scholarly journals Probing the Sea of Cosmic Rays by Measuring Gamma-Ray Emission from Passive Giant Molecular Clouds with HAWC

2021 ◽  
Vol 914 (2) ◽  
pp. 106
Author(s):  
A. Albert ◽  
R. Alfaro ◽  
C. Alvarez ◽  
J. R. Angeles Camacho ◽  
J. C. Arteaga-Velázquez ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Giant Molecular Clouds ◽  
Gamma Ray Emission

scholarly journals DISCOVERY OF GAMMA-RAY EMISSION FROM THE SUPERNOVA REMNANT Kes 17 WITH FERMI LARGE AREA TELESCOPE

2011 ◽  
Vol 740 (1) ◽  
pp. L12 ◽  
Author(s):  
J. H. K. Wu ◽  
E. M. H. Wu ◽  
C. Y. Hui ◽  
P. H. T. Tam ◽  
R. H. H. Huang ◽  
...  
Keyword(s):  
Supernova Remnant ◽  
Gamma Ray ◽  
Large Area ◽  
Gamma Ray Emission

scholarly journals Supernova remnants and the origin of cosmic rays

2013 ◽  
Vol 9 (S296) ◽  
pp. 305-314
Author(s):  
Jacco Vink
Keyword(s):  
Synchrotron Radiation ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Long Time ◽  
Gamma Ray Emission

AbstractSupernova remnants have long been considered to be the dominant sources of Galactic cosmic rays. For a long time the prime evidence consisted of radio synchrotron radiation from supernova remnants, indicating the presence of electrons with energies of several GeV. However, in order to explain the cosmic ray energy density and spectrum in the Galaxy supernova remnant should use 10% of the explosion energy to accelerate particles, and about 99% of the accelerated particles should be protons and other atomic nuclei.Over the last decade a lot of progress has been made in providing evidence that supernova remnant can accelerate protons to very high energies. The evidence consists of, among others, X-ray synchrotron radiation from narrow regions close to supernova remnant shock fronts, indicating the presence of 10-100 TeV electrons, and providing evidence for amplified magnetic fields, gamma-ray emission from both young and mature supernova remnants. The high magnetic fields indicate that the condition for accelerating protons to >1015 eV are there, whereas the gamma-ray emission from some mature remnants indicate that protons have been accelerated.

scholarly journals Kinematics of the Ultra-High-Velocity Gas in the Expanding Molecular Shell Adjacent to the W44 Supernova Remnant

2016 ◽  
Vol 11 (S322) ◽  
pp. 151-153
Author(s):  
Masaya Yamada ◽  
Tomoharu Oka ◽  
Kunihiko Tanaka ◽  
Mariko Nomura ◽  
Shunya Takekawa ◽  
...  
Keyword(s):  
High Velocity ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Supernova Remnant ◽  
Molecular Gas ◽  
Close Inspection ◽  
Essential Properties ◽  
Large Velocity ◽  
Intensity Ratios

High-velocity compact cloud (HVCC) is a peculiar category of molecular clouds detected in the central molecular zone of our Galaxy (Oka et al. 1998, 2007, and 2012). They are characterized by compact appearances (d < 5 pc) and very large velocity widths (Δ V > 50 km s−1). Some of them show high CO J=3–2/J=1–0 intensity ratios (≥ 1.5), indicating that they consist of dense and warm molecular gas. Dispite a number of efforts, we have not reached a comprehensive interpretation of HVCCs. Recently, we detected an extraordinaly broad velocity width feature, the ‘Bullet’, in the molecular cloud interacting with the W44 supernova remnant. The Bullet shares essential properties with HVCCs. Because of its proximity, a close inspection of the Bullet must contribute to the understanding of HVCCs.

scholarly journals Gamma-Ray Emission from Molecular Clouds Generated by Penetrating Cosmic Rays

2018 ◽  
Vol 868 (2) ◽  
pp. 114 ◽  
Author(s):  
V. A. Dogiel ◽  
D. O. Chernyshov ◽  
A. V. Ivlev ◽  
D. Malyshev ◽  
A. W. Strong ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Gamma Ray Emission

scholarly journals Constraining the cosmic ray spectrum in the vicinity of the supernova remnant W28: from sub-GeV to multi-TeV energies

2020 ◽  
Vol 635 ◽  
pp. A40
Author(s):  
V. H. M. Phan ◽  
S. Gabici ◽  
G. Morlino ◽  
R. Terrier ◽  
J. Vink ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Molecular Clouds ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Ionization Rate ◽  
High Energy ◽  
Radio Waves ◽  
X Ray

Context. Supernova remnants interacting with molecular clouds are ideal laboratories to study the acceleration of particles at shock waves and their transport and interactions in the surrounding interstellar medium. Aims. Here, we focus on the supernova remnant W28, which over the years has been observed in all energy domains from radio waves to very-high-energy gamma rays. The bright gamma-ray emission detected from molecular clouds located in its vicinity revealed the presence of accelerated GeV and TeV particles in the region. An enhanced ionization rate has also been measured by means of millimeter observations, but such observations alone cannot tell us whether the enhancement is due to low-energy (MeV) cosmic rays (either protons or electrons) or the X-ray photons emitted by the shocked gas. The goal of this study is to determine the origin of the enhanced ionization rate and to infer from multiwavelength observations the spectrum of cosmic rays accelerated at the supernova remnant shock in an unprecedented range spanning from MeV to multi-TeV particle energies. Methods. We developed a model to describe the transport of X-ray photons into the molecular cloud, and we fitted the radio, millimeter, and gamma-ray data to derive the spectrum of the radiating particles. Results. The contribution from X-ray photons to the enhanced ionization rate is negligible, and therefore the ionization must be due to cosmic rays. Even though we cannot exclude a contribution to the ionization rate coming from cosmic-ray electrons, we show that a scenario where cosmic-ray protons explain both the gamma-ray flux and the enhanced ionization rate provides the most natural fit to multiwavelength data. This strongly suggests that the intensity of CR protons is enhanced in the region for particle energies in a very broad range covering almost six orders of magnitude: from ≲100 MeV up to several tens of TeV.

scholarly journals On a Possible Origin of the Gamma-ray Excess around the Galactic Center

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1432
Author(s):  
Dmitry O. Chernyshov ◽  
Andrei E. Egorov ◽  
Vladimir A. Dogiel ◽  
Alexei V. Ivlev
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Molecular Clouds ◽  
Alternative Explanation ◽  
Gamma Ray ◽  
Galactic Center ◽  
The Self ◽  
Large Area ◽  
Mhd Turbulence ◽  
The Standard Model

Recent observations of gamma rays with the Fermi Large Area Telescope (LAT) in the direction of the inner galaxy revealed a mysterious excess of GeV. Its intensity is significantly above predictions of the standard model of cosmic rays (CRs) generation and propagation with a peak in the spectrum around a few GeV. Popular interpretations of this excess are that it is due to either spherically distributed annihilating dark matter (DM) or an abnormal population of millisecond pulsars. We suggest an alternative explanation of the excess through the CR interactions with molecular clouds in the Galactic Center (GC) region. We assumed that the excess could be imitated by the emission of molecular clouds with depleted density of CRs with energies below ∼10 GeV inside. A novelty of our work is in detailed elaboration of the depletion mechanism of CRs with the mentioned energies through the “barrier” near the cloud edge formed by the self-excited MHD turbulence. This depletion of CRs inside the clouds may be a reason for the deficit of gamma rays from the Central Molecular Zone (CMZ) at energies below a few GeV. This in turn changes the ratio between various emission components at those energies and may potentially absorb the GeV excess by a simple renormalization of key components.

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