scholarly journals A geomagnetic filter for the Fermi-LAT background

2019 ◽  
Vol 490 (4) ◽  
pp. 5440-5450
Author(s):  
D A Prokhorov ◽  
A Moraghan
Keyword(s):  
Charged Particles ◽  
Discrete Source ◽  
Low Earth Orbit ◽  
Shielding Effect ◽  
Earth Orbit ◽  
Next Generation ◽  
Large Area ◽  
Star Forming ◽  
Γ Rays ◽  
Γ Ray

ABSTRACT One of the unsolved questions in γ-ray astronomy is whether the extragalactic γ-ray background is of the discrete-source origin. To respond to this question, one first needs to reduce the data by differentiating charged particles from γ-rays. This procedure is usually performed on the basis of the detector responses. In this paper, we showed that the geomagnetic shielding effect at GeV energies can, to some extent, be used for this purpose for γ-ray telescopes in a low Earth orbit. We illustrated this method by applying it to the Fermi Large Area Telescope data. To partially decompose the charge-filtered background, we examined the contribution from star-forming galaxies by implying a radio/γ-ray connection in consideration of next-generation radio surveys.

scholarly journals The Gamma-ray Large Area Space Telescope (GLAST)

2002 ◽  
Vol 187 ◽  
pp. 73-77
Author(s):  
Taro Kotani
Keyword(s):  
International Collaboration ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Effective Area ◽  
Low Earth Orbit ◽  
Gamma Ray Bursts ◽  
Earth Orbit ◽  
Large Area ◽  
X Ray ◽  
Primary Instrument

AbstractGLAST, the next U.S. general gamma-ray astrophysics mission scheduled to be launched into low Earth orbit in April, 2006, for 5–10 years of operation, is described. A product of a NASA/DOE and international collaboration, the Large Area Telescope (LAT) is the primary instrument that covers the < 20 MeV to > 300 GeV band with an effective area > 8000 cm2. The angular resolution ranges from < 3.5° at 100 MeV to < 0.15° at 10 GeV. The GLAST Burst Monitor (GBM) consists of a group of NaI and BGO detectors to extend GLAST’s sensitivity to gamma-ray bursts to the < 10 keV to > 25 MeV band. GLAST’s localizations enables us to identify the X-ray, optical and radio counterparts of thousands of gamma-ray sources and to determine their nature.

scholarly journals A Possible Discovery of a Flaring 1012 eV Gamma-Ray Source near the Red Dwarf EV Lac

1995 ◽  
Vol 151 ◽  
pp. 78-79
Author(s):  
I.Yu. Alekseev ◽  
N.N. Chalenko ◽  
V.P. Fomin ◽  
R.E. Gershberg ◽  
O.R. Kalekin ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Electronic Device ◽  
Angular Size ◽  
High Energy ◽  
Optical Systems ◽  
Relativistic Electrons ◽  
Large Area ◽  
Γ Rays ◽  
Γ Ray ◽  
Ev Lac

During the 1994 coordinated observations of the red dwarf flare star EV Lac, the star was monitored in the very high energy (VHE) γ-ray range around 1012 eV with the Crimean ground-based γ-ray telescope GT-48. This telescope consists of two identical optical systems (Vladimirsky et al. 1994) which were directed in parallel on EV Lac.The detection principle of the VHE γ-rays is based on the Čerenkov radiation emitted by relativistic electrons and positrons. The latter are generated in the interaction of the γ-rays with nuclei in the Earth’s atmosphere that leads to an appearance of a shower of charged particles and γ-quanta. The duration of the Cherenkov radiation flash is very short, just about a few nanoseconds. The angular size of the shower is ∼ 1°. To detect such flashes we use an optical system with large area mirrors and a set of 37 photomultipliers (PMs) in the focal plane. Using the information from these PMs which are spaced hexagonally and correspond to a field of view of 2°.6 on the sky, we can obtain the image of an optical flash. The electronic device permits us to detect nanosecond flashes (40 ns exposure time and 12 μs readout dead-time).

NEUDOSE: A CubeSat Mission for Dosimetry of Charged Particles and Neutrons in Low-Earth Orbit

2017 ◽  
Vol 187 (1) ◽  
pp. 42-49
Author(s):  
A. R. Hanu ◽  
J. Barberiz ◽  
D. Bonneville ◽  
S. H. Byun ◽  
L. Chen ◽  
...  
Keyword(s):  
Charged Particles ◽  
Low Earth Orbit ◽  
Earth Orbit

Investigation on Sustained Discharge of Satellite’s Power Harness Due to Plasma from Space Debris Impact

2019 ◽  
Author(s):  
Yuki Mando ◽  
Koji Tanaka ◽  
Takayuki Hirai ◽  
Shirou Kawakita ◽  
Masumi Higashide ◽  
...  
Keyword(s):  
Space Debris ◽  
Internal Resistance ◽  
Low Earth Orbit ◽  
Hypervelocity Impact ◽  
Space Environment ◽  
Earth Orbit ◽  
Large Area ◽  
Solar Arrays ◽  
Sustained Discharge ◽  
Circuit Configuration

Abstract Space debris travels at a velocity of 7-8 km/s in low Earth orbit (LEO) and at 3 km/s in geostationary Earth orbit (GEO). An impact between space debris and spacecraft will result in tremendous damage. In particular, particles less than 1mm in diameter pose a risk of causing permanent sustained discharge (PSD). PSD may affect a satellite’s power system. The effect on solar arrays has been well-studied given their large area, but the effect on the bundle of a satellite’s wire harness (called the power harness) has yet to be clarified, even though the power harness is usually exposed to the space environment without protection. We conducted hypervelocity impact experiments using a two-stage light gas gun, and investigated the risk resulting in PSD from hypervelocity impacts of particles less than 1mm in size. In addition, we compared two kinds of circuit configurations: a more realistic circuit configuration with internal resistance and a circuit configuration without it, so as to investigate whether internal resistance affects the occurrence of PSD. Stainless steel and aluminum oxide projectiles measuring from 0.3 to 1 mm in diameter were gun-accelerated up to 7.16 km/s. Targets entailed a three-layered power harness under a simulated power condition of typical satellites operating in LEO or GEO. As a result, 11 of 28 shots resulted in PSD. With the more realistic circuit configuration we could not confirm any results regarding PSD. We thus found that PSD is less likely to occur in a more realistic circuit configuration.

scholarly journals A multiwavelength search for black widow and redback counterparts of candidate γ-ray millisecond pulsars

2020 ◽  
Vol 497 (4) ◽  
pp. 5364-5382
Author(s):  
C Braglia ◽  
R P Mignani ◽  
A Belfiore ◽  
M Marelli ◽  
G L Israel ◽  
...  
Keyword(s):  
Systematic Investigation ◽  
Large Area ◽  
Black Widow ◽  
Machine Learning Technique ◽  
Millisecond Pulsars ◽  
Public Data ◽  
Learning Technique ◽  
Low Mass ◽  
Γ Rays ◽  
Γ Ray

ABSTRACT The wealth of detections of millisecond pulsars (MSPs) in γ-rays by Fermi has spurred searches for these objects among the several unidentified γ-ray sources. Interesting targets are a sub-class of binary MSPs, dubbed ‘black widows’ (BWs) and ‘redbacks’ (RBs), which are in orbit with low-mass non-degenerate companions fully or partially ablated by irradiation from the MSP wind. These systems can be easily missed in radio pulsar surveys owing to the eclipse of the radio signal by the intra-binary plasma from the ablated companion star photosphere, making them better targets for multiwavelength observations. We used optical and X-ray data from public data bases to carry out a systematic investigation of all the unidentified γ-ray sources from the Fermi Large Area Telescope Third Source Catalog, which have been pre-selected as likely MSP candidates according to a machine-learning technique analysis. We tested our procedure by recovering known binary BW/RB identifications and searched for new ones, finding two possible candidates. At the same time, we investigated previously proposed BW/RB identifications and we ruled out one of them based upon the updated γ-ray source coordinates.

scholarly journals Pulsed γ-ray emission from magnetar 1E 2259+586

2012 ◽  
Vol 8 (S291) ◽  
pp. 555-557
Author(s):  
J. H. K. Wu ◽  
C. Y. Hui ◽  
R. H. H. Huang ◽  
A. K. H. Kong ◽  
K. S. Cheng ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Theoretical Models ◽  
High Energy ◽  
Large Area ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
Γ Rays ◽  
Γ Ray ◽  
High Energy Emission ◽  
Intensive Search

AbstractAnomalous X-ray pulsars (AXPs) are thought to be magnetars which are young isolated neutron stars with extremely strong magnetic fields of >1014 Gauss. Their tremendous magnetic fields inferred from the spin parameters provide a huge energy reservoir to power the observed X-ray emission. High-energy emission above 0.3 MeV has never been detected despite intensive search. Here, we present the possible Fermi Large Area Telescope (LAT) detection of γ-ray pulsations above 200 MeV from the AXP, 1E 2259+586, which puts the current theoretical models of γ-ray emission mechanisms of magnetars into challenge. We speculate that the high-energy γ-rays originate from the outer magnetosphere of the magnetar.

scholarly journals High Energy Radiation from Spider Pulsars

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 93 ◽  
Author(s):  
Chung Yue Hui ◽  
Kwan Lok Li
Keyword(s):  
High Energy ◽  
X Rays ◽  
The Novel ◽  
Large Area ◽  
High Energy Radiation ◽  
X Ray ◽  
Compact Binaries ◽  
Low Mass ◽  
Γ Rays ◽  
Γ Ray

The population of millisecond pulsars (MSPs) has been expanded considerably in the last decade. Not only is their number increasing, but also various classes of them have been revealed. Among different classes of MSPs, the behaviours of black widows and redbacks are particularly interesting. These systems consist of an MSP and a low-mass companion star in compact binaries with an orbital period of less than a day. In this article, we give an overview of the high energy nature of these two classes of MSPs. Updated catalogues of black widows and redbacks are presented and their X-ray/ γ -ray properties are reviewed. Besides the overview, using the most updated eight-year Fermi Large Area Telescope point source catalog, we have compared the γ -ray properties of these two MSP classes. The results suggest that the X-rays and γ -rays observed from these MSPs originate from different mechanisms. Lastly, we will also mention the future prospects of studying these spider pulsars with the novel methodologies as well as upcoming observing facilities.

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