| 1. |
- Acharya, B. S., et al.
(författare)
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Introducing the CTA concept
- 2013
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 43, s. 3-18
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Actis, M., et al.
(författare)
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Design concepts for the Cherenkov Telescope Array CTA : an advanced facility for ground-based high-energy gamma-ray astronomy
- 2011
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Ingår i: Experimental astronomy. - : Springer. - 0922-6435 .- 1572-9508. ; 32:3, s. 193-316
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Tidskriftsartikel (refereegranskat)abstract
- Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
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| 3. |
- de Jong, R. S., et al.
(författare)
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4MOST : Project overview and information for the First Call for Proposals
- 2019
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Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
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| 4. |
- Feroci, M., et al.
(författare)
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The large observatory for x-ray timing
- 2014
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9780819496126
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Konferensbidrag (refereegranskat)abstract
- The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.
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| 5. |
- Topchiev, N. P., et al.
(författare)
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GAMMA-400 gamma-ray observatory
- 2015
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Ingår i: Proceedings of Science. - : Proceedings of Science (PoS).
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Konferensbidrag (refereegranskat)abstract
- The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons+ positrons.Precision investigations of gamma-ray emission fromGalactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well asdiffuse gamma-rayemission,along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will studygamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The energy range of GAMMA-400 is expected to be from ∼20 MeV up to TeV energies for gamma rays, up to 10 TeV for electrons + positrons, and up to 1015eV for cosmic-ray nuclei. For high-energy gamma rays with energy from 10 to 100 GeV, the GAMMA-400 angular resolution improves from 0.1° to ∼0.01° and energy resolution from 3% to ∼1%; the proton rejection factor is ∼5x105. GAMMA-400 will be installed onboardthe Russian space observatory.
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| 6. |
- Abramowski, A., et al.
(författare)
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Simultaneous multi-wavelength campaign on PKS 2005-489 in a high state
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 533, s. A110-
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Tidskriftsartikel (refereegranskat)abstract
- The high-frequency peaked BL Lac object PKS 2005-489 was the target of a multi-wavelength campaign with simultaneous observations in the TeV gamma-ray (H.E.S.S.), GeV gamma-ray (Fermi/LAT), X-ray (RXTE, Swift), UV (Swift) and optical (ATOM, Swift) bands. This campaign was carried out during a high flux state in the synchrotron regime. The flux in the optical and X-ray bands reached the level of the historical maxima. The hard GeV spectrum observed with Fermi/LAT connects well to the very high energy (VHE, E > 100 GeV) spectrum measured with H.E.S.S. with a peak energy between similar to 5 and 500 GeV. Compared to observations with contemporaneous coverage in the VHE and X-ray bands in 2004, the X-ray flux was similar to 50 times higher during the 2009 campaign while the TeV gamma-ray flux shows marginal variation over the years. The spectral energy distribution during this multi-wavelength campaign was fit by a one zone synchrotron self-Compton model with a well determined cutoff in X-rays. The parameters of a one zone SSC model are inconsistent with variability time scales. The variability behaviour over years with the large changes in synchrotron emission and small changes in the inverse Compton emission does not warrant an interpretation within a one-zone SSC model despite an apparently satisfying fit to the broadband data in 2009.
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| 7. |
- Adriani, O., et al.
(författare)
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The gamma-400 space observatory : Status and perspectives
- 2014
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- The present design of the new space observatory GAMMA-400 is presented in this paper. The instrument has been designed for the optimal detection of gamma rays in a broad energy range (from ∼100 MeV up to 3 TeV), with excellent angular and energy resolution. The observatory will also allow precise and high statistic studies of the electron component in the cosmic rays up to the multi TeV region, as well as protons and nuclei spectra up to the knee region. The GAMMA-400 observatory will allow to address a broad range of science topics, like search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts and charged cosmic rays acceleration and diffusion mechanism up to the knee.
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| 8. |
- Leonov, A. A., et al.
(författare)
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Separation of electrons and protons in the GAMMA-400 gamma-ray telescope
- 2015
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 56:7, s. 1538-1545
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Tidskriftsartikel (refereegranskat)abstract
- The GAMMA-400 telescope will measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. These measurements will allow it to achieve the following scientific objectives: search for signatures of dark matter, investigation of gamma-ray point-like and extended sources, study of the energy spectrum of the Galactic and extragalactic diffuse emission, study of gamma-ray bursts and gamma-ray emission from the active Sun, together with high-precision measurements of the high-energy electrons and positrons spectra, protons and nuclei up to the knee. The bulk of cosmic rays are protons and helium nuclei, whereas the lepton component in the total flux is similar to 10(-3) at high energy. In the present paper, the simulated capability of the GAMMA-400 telescope to distinguish electrons and positrons from protons in cosmic rays is addressed. The individual contribution to the proton rejection from each detector system of GAMMA-400 is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of the order of similar to 4 x 10(5) for vertical incident particles and similar to 3 x 10(5) for particles with initial inclination of 30 degrees in the electron energy range from 50 GeV to 1 TeV. (C) 2015 COSPAR.
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| 9. |
- Leonov, A. A., et al.
(författare)
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The GAMMA-400 gamma-ray telescope characteristics. Angular resolution and electrons/protons separation
- 2014
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- The measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV, which will be realized by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of scientific topics. Search for signatures of dark matter, surveying the celestial sphere in order to study point and extended sources of gamma-rays, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, study of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons, protons and nuclei up to the knee. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution ~1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper, as well as, the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is investigated. The first point concerns with the space topology of high-energy gamma photon interaction in the matter of GAMMA-400. Multiple secondary particles, generated inside gamma-ray telescope, produce significant problems to restore the direction of initial gamma photon. Also back-splash particles, i.e., charged particles and gamma photons generated in calorimeter and moved upward, mask the initial tracks of electron/positron pair from conversion of incident gamma photon. The processed methods allow us to reconstruct the direction of electromagnetic shower axis and extract the electron/positron trace. As a result, the direction of incident gamma photon with the energy of 100 GeV is calculated with an accuracy of better than 0.02 deg. The main components of cosmic rays are protons and helium nuclei, whereas the part of lepton component in the total flux is ~10 -3 for high energies. The separate contribution in proton rejection is studied for each detector system of the GAMMA-400 gamma-ray telescope. Using combined information from all detector systems allow us to provide the rejection from protons with a factor of ~4 10 5 for vertical incident particles and ~3 10 5 for particle with initial inclination of 30 deg. Science with the New Generation of High Energy Gamma-ray experiments, 10th Workshop (Scineghe2014) 04-06 June 2014 Lisbon - Portugal.
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| 10. |
- Topchiev, N. P., et al.
(författare)
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The GAMMA-400 experiment : Status and prospects
- 2015
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Ingår i: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 79:3, s. 417-420
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Tidskriftsartikel (refereegranskat)abstract
- The development of the GAMMA-400 γ-ray telescope continues. The GAMMA-400 is designed to measure fluxes of γ-rays and the electron-positron cosmic-ray component possibly associated with annihilation or decay of dark matter particles; and to search for and study in detail discrete γ-ray sources, to measure the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-rays from the active Sun. The energy range for measuring γ-rays and electrons (positrons) is from 100 MeV to 3000 GeV. For 100-GeV γ-rays, the γ-ray telescope has an angular resolution of ∼0.01°, an energy resolution of ∼1%, and a proton rejection factor of ∼5 × 105. The GAMMA-400 will be installed onboard the Russian Space Observatory.
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