scholarly journals Estimation of the TeV gamma-ray duty cycle of Mrk 421 with the Milagro observatory

2014 ◽  
Vol 742 ◽  
pp. 208-211 ◽  
Author(s):  
B. Patricelli ◽  
M.M. González ◽  
N. Fraija ◽  
A. Marinelli
Keyword(s):  
Duty Cycle ◽  
Gamma Ray ◽  
Milagro Observatory

Total-dose Effects on Power MOSFET in SEPIC Converter for Nanosatellite Applications

2020 ◽  
Vol 13 (5) ◽  
pp. 758-765
Author(s):  
Saranya Krishnamurthy ◽  
Ramani Kannan ◽  
Faidhi F.A. Mohamad ◽  
Muhamad S. Ahmad ◽  
Yusof Abdullah
Keyword(s):  
Duty Cycle ◽  
Gamma Ray ◽  
Input Voltage ◽  
Heavy Ion ◽  
Radiation Environment ◽  
Power Mosfet ◽  
Dose Effects ◽  
Total Dose Effects ◽  
Improved Performance ◽  
Output Characteristics

Background: Power converters used in nanosatellite application required to be more tolerant to radiations including proton, electron and heavy-ion radiation. Methods: A Single-Ended Primary Inductance Converter (SEPIC) is selected for the nanosatellite application because of the availability to step up and down the input voltage as well as having a non-inverting polarity between the input and output voltage. In this paper, remodeled SEPIC converter proposed with an improved performance at radiation environment to work for nanosatellite application. In addition, the analysis is carried out for the irradiated power MOSFET in SEPIC converter to check its impact on converter behavior. Results: Experiments conducted with the help of power MOSFET switch used in converter, irradiated with Cobalt60 gamma ray dose level from 50krad to 300krad and output characteristics analyzed by chancing the duty cycle of converter. Investigations shown that conventional converter output characteristics were virtually constant from 10% to 60% duty cycle when different radiated MOSFETs used in the converter. Conclusion: The electrical characteristics started to fluctuate at 60% duty cycle and onwards, while the remodeled converter circuit was less distorted when increasing the radiation dose.

TeV Gamma‐Ray Survey of the Northern Hemisphere Sky Using the Milagro Observatory

2004 ◽  
Vol 608 (2) ◽  
pp. 680-685 ◽  
Author(s):  
R. Atkins ◽  
W. Benbow ◽  
D. Berley ◽  
E. Blaufuss ◽  
J. Bussons ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Gamma Ray ◽  
Milagro Observatory

scholarly journals Перспектива использования кремниевых фотоумножителей в детекторной камере малоразмерного черенковского гамма-телескопа для снижения порога регистрации космического излучения

2020 ◽  
Vol 90 (6) ◽  
pp. 925
Author(s):  
Е.Е. Холупенко ◽  
А.М. Красильщиков ◽  
Д.В. Бадмаев ◽  
А.А. Богданов ◽  
Ю.В. Тубольцев ◽  
...  
Keyword(s):  
Duty Cycle ◽  
Gamma Ray ◽  
Noise Signal ◽  
Energy Threshold ◽  
Silicon Photomultipliers ◽  
Source Signal ◽  
Night Sky ◽  
Nm Range

We have modeled propagation of source signal and noise for a future camera of TAIGA-IACT Cherenkov gamma-ray telescope, which will be based on silicon photomultipliers sensitive in the 240 -- 600 nm range. It has been shown that employment of such detectors instead of traditional vacuum photomultipliers will allow one to decrease the energy threshold by a factor of about 2.5: from ~ 1.5 TeV down to ~ 0.6 TeV. We have also shown that application of a standard ultraviolet filter ZWB3 will decrease the source signal by a factor of 3, while the noise signal from the night sky will be decreased by a factor of 6. In this way the duty cycle of the telescope can be extended (the telescope will be able to operate during moonlit nights and during twilight) and the energy threshold further decreased down to ~ 0.3 TeV. A narrow 260 -- 300 nm filter can be employed to improve gamma-hadron separation of primary cosmic particles in the ~ 25 -- 50 TeV band.

scholarly journals STUDY OF BLAZAR ACTIVITY IN 10 YEAR FERMI-LAT DATA AND IMPLICATIONS FOR TEV NEUTRINO EXPECTATIONS

2021 ◽  
Vol 57 (2) ◽  
pp. 251-268
Author(s):  
J. R. Sacahui ◽  
A. V. Penacchioni ◽  
A. Marinelli ◽  
A. Sharma ◽  
M. Castro ◽  
...  
Keyword(s):  
Duty Cycle ◽  
Gamma Ray ◽  
Active State ◽  
Light Curves ◽  
Neutrino Emission ◽  
Extragalactic Background Light ◽  
Background Light

Blazars are the most active extragalactic gamma-ray sources. They show sporadic bursts of activity, lasting from hours to months. In this work we present a 10-year analysis of a sample of bright sources detected by Fermi-LAT (100 MeV - 300 GeV). Using 2-week binned light curves (LC) we estimate the duty cycle (DC): fraction of time that the source spends in an active state. The objects show different DC values, with an average of 22.74% and 23.08% when considering (or not) the extragalactic background light ( EBL). Additionally, we study the so-called “blazar sequence” trend for the sample of selected blazars in the ten years of data. This analysis constrains a possible counterpart of sub-PeV neutrino emission during the quiescent states, leaving open the possibility to explain the observed IceCube signal during the flaring states.

scholarly journals THE STUDY OF TeV VARIABILITY AND THE DUTY CYCLE OF Mrk 421 FROM 3 Yr OF OBSERVATIONS WITH THE MILAGRO OBSERVATORY

2014 ◽  
Vol 782 (2) ◽  
pp. 110 ◽  
Author(s):  
A. A. Abdo ◽  
A. U. Abeysekara ◽  
B. T. Allen ◽  
T. Aune ◽  
A. S. Barber ◽  
...  
Keyword(s):  
Duty Cycle ◽  
Milagro Observatory

scholarly journals Gamma rays from red giant wind bubbles entering the jets of elliptical host blazars

2019 ◽  
Vol 623 ◽  
pp. A91 ◽  
Author(s):  
Núria Torres-Albà ◽  
Valentí Bosch-Ramon
Keyword(s):  
Magnetic Fields ◽  
Gamma Rays ◽  
Duty Cycle ◽  
Gamma Ray ◽  
Elliptical Galaxy ◽  
Red Giants ◽  
Local Universe ◽  
Jet Impact ◽  
Gamma Ray Emission ◽  
Red Giant

Context. Blazars in elliptical hosts have a population of red giants surrounding their jet. These stars can carry large wind-blown bubbles into the jets, leading to gamma-ray emission through bubble-jet interactions. Aims. We study the interaction dynamics and the gamma-ray emission produced when the bubbles formed by red giant winds penetrate the jet of a blazar in an elliptical galaxy. Methods. First, we characterized the masses and penetration rates of the red giant wind bubbles that enter the jet. Then, the dynamical evolution of these bubbles under the jet impact was analysed analytically and numerically, and the radiation losses of the particles accelerated in the interaction were characterised. Finally, the synchrotron and the inverse Compton contributions above ∼100 MeV were estimated under different jet magnetic fields, powers, and Lorentz factors. Results. We find that an analytical dynamical model is a reasonable approximation for the red giant wind bubble-jet interaction. The radiation produced by these wind bubbles interacting with a jet can have a duty cycle of up to ∼1. For realistic magnetic fields, gamma rays could be detectable from sources within the local universe, preferentially from those with high Lorentz factors (∼10), and this could be a relatively common phenomenon for these sources. For magnetic fields in equipartition with the jet power, and high acceleration rates, synchrotron gamma rays may be detectable even for modest Lorentz factors (∼3), but with a much lower duty cycle. Conclusions. Blazars in elliptical galaxies within the local universe can produce detectable transient or persistent gamma-ray emission from red giant wind bubbles entering their jets.

Main physics results of the ARGO-YBJ experiment

2014 ◽  
Vol 23 (09) ◽  
pp. 1430019 ◽  
Author(s):  
Giuseppe Di Sciascio
Keyword(s):  
Energy Range ◽  
High Altitude ◽  
Duty Cycle ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Wide Energy Range ◽  
Astroparticle Physics ◽  
Gamma Ray Astronomy ◽  
Wide Range ◽  
Wide Energy

The ARGO-YBJ experiment has been in stable data taking for more than 5 years at the YangBaJing Cosmic Ray Observatory (Tibet, P. R. China, 4300 m a.s.l., 606 g/cm2). With a duty-cycle greater than 86%, the detector collected about 5 × 1011 events in a wide energy range, from few hundred GeV up to about 10 PeV. High altitude location and detector features make ARGO-YBJ capable of investigating a wide range of important issues in Cosmic Ray and Astroparticle Physics by imaging the front of atmospheric showers with unprecedented resolution and detail. In this paper, the main physics results in gamma-ray astronomy and in cosmic ray physics are summarized.

scholarly journals Non-thermal emission resulting from a supernova explosion inside an extragalactic jet

2019 ◽  
Vol 622 ◽  
pp. A175 ◽  
Author(s):  
F. L. Vieyro ◽  
V. Bosch-Ramon ◽  
N. Torres-Albà
Keyword(s):  
Duty Cycle ◽  
Active Galactic Nucleus ◽  
Gamma Ray ◽  
Radio Galaxy ◽  
Thermal Emission ◽  
Dynamical Evolution ◽  
Supernova Explosion ◽  
High Energy ◽  
Spectral Energy ◽  
Starburst Galaxy

Context. Core-collapse supernovae are found in galaxies with ongoing star-formation. In a starburst galaxy hosting an active galactic nucleus with a relativistic jet, supernovae can take place inside the jet. The collision of the supernova ejecta with the jet flow is expected to lead to the formation of an interaction region, in which particles can be accelerated and produce high-energy emission. Aims. We study the non-thermal radiation produced by electrons accelerated as a result of a supernova explosion inside the jet of an active galactic nucleus within a star-forming galaxy. Methods. We first analyzed the dynamical evolution of the supernova ejecta impacted by the jet. Then, we explored the parameter space using simple prescriptions for the observed gamma-ray lightcurve. Finally, the synchrotron and the inverse Compton spectral energy distributions for two types of sources, a radio galaxy and a powerful blazar, are computed. Results. For a radio galaxy, the interaction between a supernova and a jet of power ∼1043 − 1044 erg s−1 can produce apparent gamma-ray luminosities of ∼1042 − 1043 erg s−1, with an event duty cycle of supernova remnant interacting with the jet close to one for one galaxy. For a blazar with a powerful jet of ∼1046 erg s−1, the jet-supernova ejecta interaction could produce apparent gamma-ray luminosities of ∼1043 − 1044 erg s−1, but with a much lower duty cycle. Conclusions. The interaction of supernovae with misaligned jets of moderate power can be relatively frequent, and can result in steady gamma-ray emission potentially detectable for sources in the local universe. For powerful blazars much farther away, the emission would be steady as well, and it might be detectable under very efficient acceleration, but the events would be rather infrequent.

scholarly journals Periodicity Search on X-Ray Bursts of SGR J1935+2154 Using 8.5 yr of Fermi/GBM Data

2021 ◽  
Vol 923 (2) ◽  
pp. L30
Author(s):  
Jin-Hang Zou ◽  
Bin-Bin Zhang ◽  
Guo-Qiang Zhang ◽  
Yu-Han Yang ◽  
Lang Shao ◽  
...  
Keyword(s):  
Duty Cycle ◽  
Gamma Ray ◽  
Systematic Search ◽  
Continuous Data ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Beginning Date

Abstract We performed a systematic search for X-ray bursts of the SGR J1935+2154 using the Fermi Gamma-ray Burst Monitor continuous data dated from 2013 January to 2021 October. Eight bursting phases, which consist of a total of 353 individual bursts, are identified. We further analyze the periodic properties of our sample using the Lomb–Scargle periodogram. The result suggests that those bursts exhibit a period of ∼238 days with a ∼63.2% duty cycle. Based on our analysis, we further predict two upcoming active windows of the X-ray bursts. Since 2021 July, the beginning date of our first prediction has been confirmed by the ongoing X-ray activities of the SGR J1935+2154.

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