Science Highlights from VERITAS

Staszak, D.

doi:10.22323/1.236.0868

Cited by 15 publications

(19 citation statements)

References 62 publications

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“…The existence of this spectral feature has been first discovered by the HESS Collaboration [15], confirmed by MAGIC [16] and VERITAS [17], and then also clearly seen by DAMPE detector [13]. The results of FERMI [11] are actually consistent with an unbroken power law spectrum, but the errors of the highest energy points, that reach 2 TeV are large, and this does not appear to be a significant discrepancy.…”

Section: Data Setmentioning

confidence: 69%

“…The data is fitted using the best fit function obtained for the AMS data, assuming a constant energy rescaling factor f = E PAM /E AMS , and a difference in the FFA modulation parameter ∆ε = ε PAM − ε AMS . [11], ATIC [12], DAMPE [13], HESS [14,15,18], MAGIC [16], and VERITAS [17]. The line is a fit to the data from [19] cannot reproduce exactly these precisely measured spectra however in a reasonably good first approximation it still gives a good description of the data, as shown in Fig.…”

Section: Observationsmentioning

confidence: 98%

“…Ground based Cherenkov telescopes such as HESS [14,15], MAGIC [16] and VERITAS [17], have also been able to obtained measurements of the (e − + e + ) spectrum in the TeV energy range. The measurements are performed selecting events that are consistent with an electromagnetic shower, and subtracting the background generated by cosmic ray protons and nuclei using Montecarlo codes to model the developments of air showers.…”

Section: Data Setmentioning

confidence: 99%

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Spectral shapes of the fluxes of electrons and positrons and the average residence time of cosmic rays in the Galaxy

Lipari

2019

Phys. Rev. D

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The cosmic ray energy spectra encode very important information about the mechanisms that generate relativistic particles in the Milky Way, and about the properties of the Galaxy that control their propagation. Relativistic electrons and positrons traveling in interstellar space lose energy much more rapidly than more massive particles such as protons and nuclei, with a rate that grows quadratically with the particle energy E. One therefore expects that the effects of energy loss should leave observable signatures in the e ∓ spectra, in the form of softenings centered at the critical energy E * . This quantity is determined by the condition that the total energy loss suffered by particles during their residence time in the Galaxy is of the same order of the initial energy. If the electrons and positrons are accelerated in discrete (quasi) point-like astrophysical objects, such as Supernova explosions or Pulsars, the stochastic nature of the sources should also leave observable signatures in the e ∓ energy spectra and angular distributions above a second (higher) critical energy E † , determined by the condition that particles with E E † can propagate only for a maximum distance shorter than the average separation between sources. In this work we discuss the theoretically expectations for the signatures of the energy loss effects on the electron and positron spectra, and compare these predictions with the existing observations. Recent measurements of the (e − + e + ) flux have discovered the existence of a prominent spectral break at E 1 TeV. This spectral feature can perhaps be identified with the critical energy E * . An alternative hypothesis is to assmume that E * has a much lower value of order few GeV. Resolving this ambiguity is of great importance for our understanding of Galactic cosmic rays.PACS numbers: 98.35Gi,95.85Pw,95.85Ry I. INTRODUCTIONThe fluxes of cosmic rays (CR) that are observable near the Earth, in a very broad energy interval that extends from GeV's to PeV's (and possibly to much higher energy) are formed by particles of Galactic origin. These CR particles are injected in interstellar space by sources distributed in the entire Milky Way, and remain confined in the Galaxy for an extended period of time because of the existence of the Galactic magnetic fields. The CR fluxes are in very good approximation isotropic, but their energy distributions contain very important information about their sources and about the properties of the Galaxy that control CR propagation. At low energy (E 30 GeV) the CR spectra are also distorted by the electromagnetic fields that fill the heliosphere, generating time dependent solar modulations.A fundamental problem for CR astrophysics is to disentangle the roles of the sources and of propagation in the formation of the CR fluxes, reconstructing from the observations the "source spectra" (that is the spectra with which the particles are injected in interstellar space by the sources), and the distortion effects generated by propagation.Relativistic, electrically ch...

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Section: Data Setmentioning

confidence: 69%

Section: Observationsmentioning

confidence: 98%

Section: Data Setmentioning

confidence: 99%

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Spectral shapes of the fluxes of electrons and positrons and the average residence time of cosmic rays in the Galaxy

Lipari

2019

Phys. Rev. D

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“…It is located at the Fred Lawrence Whipple Observatory in southern Arizona (31 40 N, 110 57 W) and consists of an array of four imaging atmospheric-Cherenkov telescopes (for details on the instrument and its performance see [10,11,12]). HESS J0632+057 has been observed by the VERITAS observatory for a total of 200 hours between 2006 December and 2015 January at energies above ≈200 GeV.…”

Section: Gamma-ray and X-ray Observationsmentioning

confidence: 99%

Long-term TeV Observations of the Gamma-ray Binary HESS J0632+057 with VERITAS

Maier¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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The gamma-ray binary HESS J0632+057 has been observed at very-high energies for almost ten years by all major systems of imaging atmospheric Cherenkov telescopes. We present new observations taken by the VERITAS observatory and an updated analysis of the previously published observations. HESS J0632+057 has been detected by VERITAS with a total significance > 20σ at energies above 350 GeV in about 200 hours of observations. The exposure covers now almost the entire orbital period of 315 days including the flux enhancements at phases ≈0.35 and, for the first time, detected with VERITAS, at phases ≈0.75. The results are discussed along with simultaneous observations by the X-ray satellite Swift XRT.

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“…• 57 W) and consists of an array of four imaging atmospheric-Cherenkov telescopes (details of the instrument and its performance were described previously [5,6,7]). …”

Section: Long-term Observations With Veritas and Swift-xrtmentioning

confidence: 99%

A decade of TeV observations of the gamma-ray binary HESS J0632+057 with VERITAS

Schlenstedt

2017

AIP Conference Proceedings

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Abstract. The gamma-ray binary HESS J0632+057 (VER J0633+057) has been observed at very-high energies for a decade by all major systems of imaging atmospheric Cherenkov telescopes. We present here new observations taken by the VERITAS observatory during the season 2015-2016. The observations cover now all phases of the binary orbit (with its period of about 315 days), showing clearly enhancements around phases 0.35 and 0.75. The results are discussed along with simultaneous observations with Swift's X-Ray Telescope.

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Science Highlights from VERITAS

Cited by 15 publications

References 62 publications

Spectral shapes of the fluxes of electrons and positrons and the average residence time of cosmic rays in the Galaxy

Spectral shapes of the fluxes of electrons and positrons and the average residence time of cosmic rays in the Galaxy

Long-term TeV Observations of the Gamma-ray Binary HESS J0632+057 with VERITAS

A decade of TeV observations of the gamma-ray binary HESS J0632+057 with VERITAS

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