scholarly journals DIFFUSE HARD X-RAY EMISSION IN STARBURST GALAXIES AS SYNCHROTRON FROM VERY HIGH ENERGY ELECTRONS

2012 ◽  
Vol 762 (1) ◽  
pp. 29 ◽  
Author(s):  
Brian C. Lacki ◽  
Todd A. Thompson
Keyword(s):  
High Energy ◽  
Starburst Galaxies ◽  
X Ray ◽  
High Energy Electrons ◽  
Very High Energy ◽  
Very High

scholarly journals Dosimetry and radioprotection evaluations of very high energy electron beams

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thongchai A. M. Masilela ◽  
Rachel Delorme ◽  
Yolanda Prezado
Keyword(s):  
Neutron Yield ◽  
High Energy ◽  
Clinical Implementation ◽  
Dose Equivalent ◽  
Concrete Wall ◽  
Promising Alternative ◽  
High Energy Electrons ◽  
Ambient Dose Equivalent ◽  
Very High Energy ◽  
Very High

AbstractVery high energy electrons (VHEEs) represent a promising alternative for the treatment of deep-seated tumors over conventional radiotherapy (RT), owing to their favourable dosimetric characteristics. Given the high energy of the electrons, one of the concerns has been the production of photoneutrons. In this article we explore the consequence, in terms of neutron yield in a water phantom, of using a typical electron applicator in conjunction with a 2 GeV and 200 MeV VHEE beam. Additionally, we evaluate the resulting ambient neutron dose equivalent at various locations between the phantom and a concrete wall. Through Monte Carlo (MC) simulations it was found that an applicator acts to reduce the depth of the dose build-up region, giving rise to lower exit doses but higher entrance doses. Furthermore, neutrons are injected into the entrance region of the phantom. The highest dose equivalent found was approximately 1.7 mSv/Gy in the vicinity of the concrete wall. Nevertheless, we concluded that configurations of VHEEs studied in this article are similar to conventional proton therapy treatments in terms of their neutron yield and ambient dose equivalent. Therefore, a clinical implementation of VHEEs would likely not warrant additional radioprotection safeguards compared to conventional RT treatments.

scholarly journals Back to the Future: Very High-Energy Electrons (VHEEs) and Their Potential Application in Radiation Therapy

Cancers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 4942
Author(s):  
Maria Grazia Ronga ◽  
Marco Cavallone ◽  
Annalisa Patriarca ◽  
Amelia Maia Leite ◽  
Pierre Loap ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Current Knowledge ◽  
High Energy ◽  
High Dose Rate ◽  
Point Of View ◽  
High Dose ◽  
Dose Rates ◽  
High Energy Electrons ◽  
Very High Energy ◽  
Very High

The development of innovative approaches that would reduce the sensitivity of healthy tissues to irradiation while maintaining the efficacy of the treatment on the tumor is of crucial importance for the progress of the efficacy of radiotherapy. Recent methodological developments and innovations, such as scanned beams, ultra-high dose rates, and very high-energy electrons, which may be simultaneously available on new accelerators, would allow for possible radiobiological advantages of very short pulses of ultra-high dose rate (FLASH) therapy for radiation therapy to be considered. In particular, very high-energy electron (VHEE) radiotherapy, in the energy range of 100 to 250 MeV, first proposed in the 2000s, would be particularly interesting both from a ballistic and biological point of view for the establishment of this new type of irradiation technique. In this review, we examine and summarize the current knowledge on VHEE radiotherapy and provide a synthesis of the studies that have been published on various experimental and simulation works. We will also consider the potential for VHEE therapy to be translated into clinical contexts.

Very high energy gamma rays from x-ray binary pulsars

1990 ◽  
Vol 16 (12) ◽  
pp. 1773-1803 ◽  
Author(s):  
P M Chadwick ◽  
T J L McComb ◽  
K E Turver
Keyword(s):  
Gamma Rays ◽  
High Energy ◽  
X Ray ◽  
Binary Pulsars ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

scholarly journals Toward an effective use of laser-driven very high energy electrons for radiotherapy: Feasibility assessment of multi-field and intensity modulation irradiation schemes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Luca Labate ◽  
Daniele Palla ◽  
Daniele Panetta ◽  
Federico Avella ◽  
Federica Baffigi ◽  
...  
Keyword(s):  
High Energy ◽  
High Dose Rate ◽  
High Dose ◽  
Feasibility Assessment ◽  
High Energy Electrons ◽  
Very High Energy ◽  
Effective Use ◽  
Dose Deposition ◽  
Therapeutic Doses ◽  
Very High

Abstract Radiotherapy with very high energy electrons has been investigated for a couple of decades as an effective approach to improve dose distribution compared to conventional photon-based radiotherapy, with the recent intriguing potential of high dose-rate irradiation. Its practical application to treatment has been hindered by the lack of hospital-scale accelerators. High-gradient laser-plasma accelerators (LPA) have been proposed as a possible platform, but no experiments so far have explored the feasibility of a clinical use of this concept. We show the results of an experimental study aimed at assessing dose deposition for deep seated tumours using advanced irradiation schemes with an existing LPA source. Measurements show control of localized dose deposition and modulation, suitable to target a volume at depths in the range from 5 to 10 cm with mm resolution. The dose delivered to the target was up to 1.6 Gy, delivered with few hundreds of shots, limited by secondary components of the LPA accelerator. Measurements suggest that therapeutic doses within localized volumes can already be obtained with existing LPA technology, calling for dedicated pre-clinical studies.

scholarly journals Long-term multiwavelength view of the blazar 1ES 1218+304

2019 ◽  
Vol 489 (4) ◽  
pp. 5076-5086 ◽  
Author(s):  
K K Singh ◽  
B Bisschoff ◽  
B van Soelen ◽  
A Tolamatti ◽  
J P Marais ◽  
...  
Keyword(s):  
High Energy ◽  
Host Galaxy ◽  
Energy Bands ◽  
X Ray ◽  
Very High Energy ◽  
Γ Ray ◽  
Activity State ◽  
Low Activity ◽  
Very High

ABSTRACT In this work, we present a multiwavelength study of the blazar 1ES 1218+304 using near simultaneous observations over 10 yr during the period 2008 September 1 to 2018 August 31 (MJD 54710–58361). We have analysed data from Swift-UVOT, Swift-XRT, and Fermi-LAT to study the long term behaviour of 1ES 1218+304 in different energy bands over the last decade. We have also used the archival data from OVRO, MAXI, and Swift-BAT available during the above period. The near simultaneous data on 1ES 1218+304 suggest that the long term multiwavelength emission from the source is steady and does not show any significant change in the source activity. The optical/UV fluxes are found to be dominated by the host galaxy emission and can be modelled using the pegase code. However, the time averaged X-ray and γ-ray emissions from the source are reproduced using a single zone leptonic model with log-parabolic distribution for the radiating particles. The intrinsic very high energy γ-ray emission during a low activity state of the source is broadly consistent with the predictions of the leptonic model for blazars. We have investigated the physical properties of the jet and the mass of the supermassive black hole at the centre of the host galaxy using long term X-ray observations from the Swift-XRT which is in agreement with the value derived using blackbody approximation of the host galaxy. We also discuss the extreme nature of the source on the basis of X-ray and γ-ray observations.

scholarly journals A New Chapter in Hard X-rays of the M87 AGN

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 9
Author(s):  
Ka-Wah Wong ◽  
Rodrigo S. Nemmen ◽  
Jimmy A. Irwin ◽  
Dacheng Lin
Keyword(s):  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Accretion Flow ◽  
Relativistic Jet ◽  
Very High Energy ◽  
Γ Ray ◽  
High Energy Emission ◽  
First Time ◽  
Very High

The nearby M87 hosts an exceptional relativistic jet. It has been regularly monitored in radio to TeV bands, but little has been done in hard X-rays ≳10 keV. For the first time, we have successfully detected hard X-rays up to 40 keV from its X-ray core with joint Chandra and NuSTAR observations, providing important insights to the X-ray origins: from the unresolved jet or the accretion flow. We found that the hard X-ray emission is significantly lower than that predicted by synchrotron self-Compton models introduced to explain very-high-energy γ -ray emission above a GeV. We discuss recent models to understand these high energy emission processes.

scholarly journals Nonthermal processes in microquasars

2010 ◽  
Vol 6 (S275) ◽  
pp. 215-223
Author(s):  
Valentí Bosch-Ramon
Keyword(s):  
Thermal Emission ◽  
High Energy ◽  
Energy Bands ◽  
X Ray ◽  
Radio Jets ◽  
Extended Radio ◽  
Very High Energy ◽  
X Ray Binaries ◽  
Very High ◽  
Negligible Contribution

AbstractMicroquasars are X-ray binaries that show extended radio jets. These jets can accelerate particles up to relativistic energies that produce non-thermal emission from radio to TeV, and could also make a non-negligible contribution to the galactic CRs in some energy ranges. The orbital motion and compactness of these sources allow the study of high-energy astrophysical phenomena in extreme conditions that change in accessible timescales. In this work, I briefly discuss the production of broadband non-thermal emission in microquasars, putting special emphasis on the high- and the very high-energy bands.

scholarly journals New composite supernova remnant toward HESS J1844-030?

2019 ◽  
Vol 626 ◽  
pp. A65
Author(s):  
A. Petriella
Keyword(s):  
Supernova Remnant ◽  
High Energy ◽  
Radio Continuum ◽  
Pressure Balance ◽  
High Energy Radiation ◽  
X Ray ◽  
Galactic Source ◽  
Very High Energy ◽  
The Magnetic Field ◽  
Very High

Aims. HESS J1844-030 is a newly confirmed TeV source in the direction of the X-ray pulsar wind nebula (PWN) candidate G29.4+0.1 and the complex radio source G29.37+0.1, which is likely formed by the superposition of a background radio galaxy and a Galactic supernova remnant (SNR). Many scenarios have been proposed to explain the origin of HESS J1844-030, based on several sources that are capable of producing very high energy radiation. We investigate the possible connection between the SNR, the PWN G29.4+0.1, and HESS J1844-030 to shed light on the astrophysical origin of the TeV emission. Methods. We performed an imaging and spectral study of the X-ray emission from the PWN G29.4+0.1 using archival observations obtained with the Chandra and XMM-Newton telescopes. Public radio continuum and HI data were used to derive distance constraints for the SNR that is linked to G29.37+0.1 and to investigate the interstellar medium where it is expanding. We applied a simple model of the evolution of a PWN inside an SNR to analyze the association between G29.4+0.1 and the radio emission from G29.37+0.1. We compared the spectral properties of the system with the population of TeV PWNe to investigate if HESS J1844-030 is the very high energy counterpart of the X-ray PWN G29.4+0.1. Results. Based on the morphology and spectral behavior in the X-ray band, we conclude that G29.4+0.1 is a PWN and that a point source embedded on it is the powering pulsar. The HI data revealed that the SNR linked to G29.37+0.1 is a Galactic source at 6.5 kpc and expanding in a nonuniform medium. From the analysis of the pulsar motion and the pressure balance at the boundary of X-ray emission, we conclude that G29.4+0.1 could be a PWN that is located inside its host remnant, forming a new composite SNR. Based on the magnetic field of the PWN obtained from the X-ray luminosity, we found that the population of electrons producing synchrotron radiation in the keV band can also produce IC photons in the TeV band. This suggests that HESS J1844-030 could be the very high energy counterpart of G29.4+0.1.

scholarly journals MAXIINVESTIGATION INTO THE LONG-TERM X-RAY VARIABILITY FROM THE VERY-HIGH-ENERGY γ-RAY BLAZAR Mrk 421

2014 ◽  
Vol 798 (1) ◽  
pp. 27 ◽  
Author(s):  
Naoki Isobe ◽  
Ryosuke Sato ◽  
Yoshihiro Ueda ◽  
Masaaki Hayashida ◽  
Megumi Shidatsu ◽  
...  
Keyword(s):  
High Energy ◽  
X Ray ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

scholarly journals OBSERVATIONS OF MICROQUASAR CANDIDATES WITH THE MAGIC TELESCOPE

2008 ◽  
Vol 17 (10) ◽  
pp. 1859-1866
Author(s):  
◽  
J. RICO
Keyword(s):  
Black Hole ◽  
Experimental Evidence ◽  
Energy Band ◽  
High Energy ◽  
Time Dependent ◽  
X Ray ◽  
Orbital Cycles ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

We report on the results from the observations in very high energy band (VHE, Eγ ≥ 100 GeV ) of the γ-ray binary LS I +61 303 and the black hole X-ray binary (BHXB) Cygnus X-1. LS I +61 303 was recently discovered at VHE by MAGIC1 and here we present the preliminary results from an extensive observation campaign, comprising 112 observation hours covering 4 orbital cycles, aiming at determining the time-dependent features of the VHE emission. Cygnus X-1 was observed for a total of 40 hours during 26 nights, spanning the period between June and November 2006. We report on the results of the searches for steady and variable γ-ray signals from Cygnus X-1, including the first experimental evidence for an intense flare, of duration between 1.5 and 24 hours.

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