scholarly journals A GeV-TeV particle component and the barrier of cosmic-ray sea in the Central Molecular Zone

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoyuan Huang ◽  
Qiang Yuan ◽  
Yi-Zhong Fan
Keyword(s):  
Cosmic Rays ◽  
Galactic Center ◽  
Cosmic Ray ◽  
High Energy ◽  
Particle Accelerator ◽  
High Energy Particle ◽  
Spatial Gradient ◽  
Large Area ◽  
Cherenkov Telescopes ◽  
Very High Energy

AbstractCosmic rays are important probe of a number of fundamental physical problems such as the acceleration of high and very high energy particles in extreme astrophysical environments. The Galactic center is widely anticipated to be an important cosmic-ray source and the observations of some Imaging Atmospheric Cherenkov Telescopes did successfully reveal a component of TeV-PeV cosmic rays in the vicinity of the Galactic center. Here we report the identification of GeV-TeV cosmic rays in the central molecular zone with the γ-ray observations of the Fermi Large Area Telescope, whose spectrum and spatial gradient are consistent with that measured by the Imaging Atmospheric Cherenkov Telescopes but the corresponding cosmic-ray energy density is substantially lower than the so-called cosmic-ray sea component, suggesting the presence of a high energy particle accelerator at the Galactic center and the existence of a barrier that can effectively suppress the penetration of the particles from the cosmic-ray sea to the central molecular zone.

scholarly journals Time-dependent escape of cosmic rays from supernova remnants potentially at the origin of the very-high-energy cosmic-ray gradient of the Galactic center

2020 ◽  
Vol 644 ◽  
pp. A113
Author(s):  
L. Jouvin ◽  
A. Lemière ◽  
R. Terrier
Keyword(s):  
Cosmic Rays ◽  
Supernova Remnants ◽  
Galactic Center ◽  
Large Fraction ◽  
Surrounding Medium ◽  
Cosmic Ray ◽  
High Energy ◽  
Very High Energy ◽  
Energy Dependent ◽  
Very High

The distribution of the very-high-energy diffuse emission in the inner 200 pc measured by H.E.S.S. indicates the existence of a pronounced cosmic-ray (CR) gradient peaking on the Galactic center (GC). Previous studies have shown that these data are consistent with a scenario in which the CRs are diffused away from a stationary source at the GC. We previously showed that, taking the 3D gas distribution and a realistic distribution of supernova explosions into account, CRs accelerated in supernova remnants should account for a large fraction of the GC CRs observed by H.E.S.S.; but the model did not fully reproduce the apparent over-density in the inner 30 pc. In this work, we study the time-energy dependent cosmic rays escape from the remnant that is expected to occur when the shock wave decelerates in the surrounding medium. We show that the resulting CR distribution follows the quasi-stationary profile observed by H.E.S.S. more closely. The main signature is that the energy-dependent escape creates a strong dependency of the morphology of the γ-ray emission with the energy. The existence of this energy dependency should be observable by the Cherenkov Telescope Array.

scholarly journals Observation of the Energy Dependence of Primary and Secondary Cosmic Rays with the AMS Detector on the International Space Station

2019 ◽  
Vol 209 ◽  
pp. 01020
Author(s):  
V. Formato
Keyword(s):  
Cosmic Rays ◽  
Supernova Remnants ◽  
Space Station ◽  
Cosmic Ray ◽  
High Energy ◽  
High Energy Particle ◽  
Detailed Knowledge ◽  
Precision Study ◽  
Peculiar Case ◽  
Primary Cosmic Rays

Precision study of cosmic nuclei provides detailed knowledge on the origin and propagation of cosmic rays. AMS is a multi-purpose high energy particle detector designed to measure and identify cosmic ray nuclei with unprecedented precision. It is able to provide precision studies of nuclei simultaneously to multi-TeV energies. In 7 years on the Space Station, AMS has collected more than 120 billion both primary and secondary cosmic rays. Primary cosmic rays, such as p, He, C and O, are believed to be mainly produced and accelerated in supernova remnants, while secondary cosmic rays, such as Li, Be and B are thought to be produced by collisions of heavier nuclei with interstellar matter. Primary cosmic rays such as He, C, and O are found to have identical rigidity dependence, similarly to secondary cosmic rays (such as Li, Be and B) which share the same the same spectral shape. The peculiar case of Nitrogen being a mixture of a primary and secondary component will also be shown.

scholarly journals Interpreting correlated observations of cosmic rays and gamma-rays from Centaurus A with a proton blazar inspired model

2020 ◽  
Vol 500 (1) ◽  
pp. 1087-1094
Author(s):  
Prabir Banik ◽  
Arunava Bhadra ◽  
Abhijit Bhattacharyya
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Energy Scale ◽  
Electromagnetic Spectrum ◽  
Ultrahigh Energy ◽  
Large Area ◽  
Centaurus A

ABSTRACT The nearest active radio galaxy Centaurus (Cen) A is a gamma-ray emitter in GeV–TeV energy scale. The high energy stereoscopic system (HESS) and non-simultaneous Fermi–Large Area Telescope observation indicate an unusual spectral hardening above few GeV energies in the gamma-ray spectrum of Cen A. Very recently the HESS observatory resolved the kilo parsec (kpc)-scale jets in Centaurus A at TeV energies. On the other hand, the Pierre Auger Observatory (PAO) detects a few ultrahigh energy cosmic ray (UHECR) events from Cen-A. The proton blazar inspired model, which considers acceleration of both electrons and hadronic cosmic rays in active galactic nuclei (AGN) jet, can explain the observed coincident high-energy neutrinos and gamma-rays from Ice-cube detected AGN jets. Here, we have employed the proton blazar inspired model to explain the observed GeV–TeV gamma-ray spectrum features including the spectrum hardening at GeV energies along with the PAO observation on cosmic rays from Cen-A. Our findings suggest that the model can explain consistently the observed electromagnetic spectrum in combination with the appropriate number of UHECRs from Cen A.

scholarly journals Search for Very High-energy Emission from the Millisecond Pulsar PSR J0218+4232

2021 ◽  
Vol 922 (2) ◽  
pp. 251
Author(s):  
V. A. Acciari ◽  
S. Ansoldi ◽  
L. A. Antonelli ◽  
A. Arbet Engels ◽  
M. Artero ◽  
...  
Keyword(s):  
High Energy ◽  
Theoretical Modeling ◽  
Millisecond Pulsar ◽  
Large Area ◽  
Telescope Array ◽  
Cherenkov Telescopes ◽  
Gamma Imaging ◽  
Very High Energy ◽  
High Energy Emission ◽  
Very High

Abstract PSR J0218+4232 is one of the most energetic millisecond pulsars known and has long been considered as one of the best candidates for very high-energy (VHE; >100 GeV) γ-ray emission. Using 11.5 yr of Fermi Large Area Telescope (LAT) data between 100 MeV and 870 GeV, and ∼90 hr of Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observations in the 20 GeV to 20 TeV range, we searched for the highest energy γ-ray emission from PSR J0218+4232. Based on the analysis of the LAT data, we find evidence for pulsed emission above 25 GeV, but see no evidence for emission above 100 GeV (VHE) with MAGIC. We present the results of searches for γ-ray emission, along with theoretical modeling, to interpret the lack of VHE emission. We conclude that, based on the experimental observations and theoretical modeling, it will remain extremely challenging to detect VHE emission from PSR J0218+4232 with the current generation of Imaging Atmospheric Cherenkov Telescopes, and maybe even with future ones, such as the Cherenkov Telescope Array.

scholarly journals Opening Remarks ~ Prospects of very high energy cosmic ray interactions for astroparticle physics

2019 ◽  
Vol 208 ◽  
pp. 01001
Author(s):  
Yoshitaka Itow
Keyword(s):  
Cosmic Rays ◽  
Particle Production ◽  
Cosmic Ray ◽  
High Energy ◽  
Hadronic Interactions ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Interactions ◽  
Precise Knowledge ◽  
Very High Energy ◽  
Very High

Hadronic interactions of very high energy cosmic rays have been studied in various aspects of motivation. In recent decades, mainly motivated by air shower experiments, modelling of very high energy cosmic ray interactions have been greatly improved together with new data obtained from high energy colliders such as the LHC. Regarding recent rapid progress of multi-messenger astronomy, a precise knowledge on secondary particle production by cosmic rays at very high energy is largely indispensable. This would give us a new insight and new motivation to study minimum bias hadronic interactions of very high energy cosmic rays.

TeV observations of the Galactic center and starburst galaxies

2013 ◽  
Vol 9 (S303) ◽  
pp. 29-42
Author(s):  
Mathieu de Naurois
Keyword(s):  
Black Hole ◽  
Cosmic Rays ◽  
Galactic Center ◽  
High Energy ◽  
Starburst Galaxies ◽  
Energy Emission ◽  
Very High Energy ◽  
Sgr A ◽  
High Energy Emission ◽  
Very High

AbstractThe vicinity of the Galactic center harbors many potential accelerators of cosmic rays (CR) that could shine in very-high-energy (VHE) γ-rays, such as pulsar wind nebulae, supernova remnants, binary systems and the central black hole Sgr A*, and is characterized by high gas density, large magnetic fields and a high rate of starburst activity similar to that observed in the core of starburst galaxies. In addition to these astrophysical sources, annihilation of putative WIMPs concentrated in the gravitational well could lead to significant high-energy emission at the Galactic center. The Galactic center region has been observed by atmospheric Cherenkov telescopes, and in particular by the H. E. S. S. array in Namibia for the last ten years above 150 GeV. This large data set, comprising more than 200 hours of observations, led to the discovery of a point-like source spatially compatible with the supermassive black hole Sgr A*, and to an extended diffuse emission, correlated with molecular clouds and attributed to the interaction of cosmic rays with the interstellar medium. Over the same time period, two starburst galaxies, namely M 82 and NGC 253, were detected at TeV energies after very deep exposures. Results from these ten years of observations of the Galactic center region and starburst galaxies at TeV energies are presented, and implications for the various very-high-energy emission mechanisms are discussed.

scholarly journals Gamma-ray burst detection prospects for next generation ground-based VHE facilities

2021 ◽  
Author(s):  
G La Mura ◽  
U Barres de Almeida ◽  
R Conceição ◽  
A De Angelis ◽  
F Longo ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Large Area ◽  
Gamma Ray Burst ◽  
Cherenkov Telescopes ◽  
200 Gev ◽  
Energy Domain ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

Abstract Gamma-ray Bursts (GRB) were discovered by satellite-based detectors as powerful sources of transient γ-ray emission. The Fermi satellite detected an increasing number of these events with its dedicated Gamma-ray Burst Monitor (GBM), some of which were associated with high energy photons (E > 10 GeV), by the Large Area Telescope (LAT). More recently, follow-up observations by Cherenkov telescopes detected very high energy emission (E > 100 GeV) from GRBs, opening up a new observational window with implications on the interpretation of their central engines and on the propagation of very energetic photons across the Universe. Here, we use the data published in the 2nd Fermi-LAT Gamma Ray Burst Catalogue to characterise the duration, luminosity, redshift and light curve of the high energy GRB emission. We extrapolate these properties to the very high energy domain, comparing the results with available observations and with the potential of future instruments. We use observed and simulated GRB populations to estimate the chances of detection with wide-eld ground-based γ-ray instruments. Our analysis aims to evaluate the opportunities of the Southern Wide-eld-of-view Gamma-ray Observatory (SWGO), to be installed in the Southern Hemisphere, to complement CTA. We show that a low-energy observing threshold (Elow < 200 GeV), with good point source sensitivity (Flim ≈ 10−11erg cm−2 s−1 in 1 yr), are optimal requirements to work as a GRB trigger facility and to probe the burst spectral properties down to time scales as short as 10 s, accessing a time domain that will not be available to IACT instruments.

Triggered spark counter arrays of large area (square meters) for experiments on very high energy cosmic ray particles

1960 ◽  
Vol 17 (3) ◽  
pp. 429-437 ◽  
Author(s):  
N. B. Mistry ◽  
G. T. Murthy ◽  
P. V. Ramana Murthy ◽  
B. V. Sreekantan
Keyword(s):  
Cosmic Ray ◽  
High Energy ◽  
Large Area ◽  
Spark Counter ◽  
Very High Energy ◽  
Very High
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