2016

2016-06

http://arxiv.org/abs/1606.00947

Physics at a 100 TeV pp collider: beyond the Standard Model phenomena

T. Golling et al.

Figure 40 shows the current bounds for the experiments. Both of the search regions are expected to improve with the upcoming launch of DAMPE [300] and GAMMA-400 [301]. Further improvements at high energy will come with the Cherenkov Telescope Array (CTA) [302]. These further extensions are shown in figure 40. The goal is to cover the model independent calculation of the relic density shown in figure 40. This allows for an exclusion/discovery benchmark of a large class of models. The relic density line can be avoided through models with p-wave annihilation or co-annihilation. In some models, direct photon line searches are more sensitive than broad spectrum searches. In figure 40, we also show the direct photon bounds searches and the extrapolated improvements [303, 304] given a consistent level of improvement as that projected with the future continuum searches.

2016-05

http://arxiv.org/abs/1605.03224

Gamma-ray Signals from Dark Matter Annihilation Via Charged Mediators

J. Kumar, P. Sandick, Fei Teng, and T. Yamamoto

The search for line signals of dark matter annihilation has been one of the primary goals of various ground-based and satellite-based experiments. In general, the ground-based atmospheric Cherenkov telescopes [23] are most effective for dark matter that is somewhat heavier than 100 GeV. For example, with 500 hours of observing time, CTA will be sensitive to cross sections ~ 10^-27 cm³/s for dark matter with mass of ~ 300 GeV annihilating to τ⁺τ^- in the Galactic Center region [24]. Due to its much lower energy threshold, the Fermi Gamma-Ray Space Telescope is better suited to study dark matter masses in the range 0.1 to a few hundred GeV, which is the range we are interested in here. For m_X ≤ 100 GeV, the Fermi Large Area Telescope (LAT) has set a limit on the thermally-averaged annihilation cross section to γγ of ‹σv›_γγ ≈ 10^-28 ~ 10^-29 cm³/s with the 95% C.L. containment spanning approximately one order of magnitude using the PASS 8 analysis of 5.8 years of data [25]. However, this limit, as well as any projected sensitivities, are sensitive to the dark matter profile of the Milky Way halo, and may move up or down by about one order of magnitude for different profiles. We hope that the sensitivity to ‹σv›_γγ will be improved with additional data and/or new technology. Future satellite-based experiments GAMMA-400 [26] and HERD [27] are expected to reach ‹σv›_γγ ≤ 10^-28 cm³/s for m_X = 100 GeV. In addition, each of these experiments is expected to have energy resolution of ~1%, which is much better than Fermi-LAT's (~10% at 100 GeV), making it possible to distinguish between a sharply peaked IB spectrum and a true line signal.

[26] N. P. Topchiev et al., in Proceedings, 34th International Cosmic Ray Conference (ICRC 2015) (2015) arXiv:1507.06246 [astro-ph.IM].

2016-04

http://arxiv.org/abs/1604.05488

Introduction to high-energy gamma-ray astronomy

Bernard Degrange and G´erard Fontaine

GAMMA-400: Gamma Astronomical Multifunctional Modular Apparatus with the maximum gamma-ray energy

of 400 GeV.

2016-04

http://arxiv.org/abs/1604.05247

Search for a Dark Matter component

A. Giordano, G.N. Izmailov, R.De Luca, A.M. Tskovrebov, L.N. Zherikhina, V.A. Ryabov

Indirect registration of DM particles, by their annihilation products in cosmic rays, requires the detection of TeV gamma rays. However, as it is well known [9], such a quantum creates in the Earth's atmosphere a wide (a few kilometers) electromagnetic air shower of secondary particles that significantly complicates the determination of the total energy of the original photon. Among the projects for registration of 1÷15TeV gamma rays in space-based experiments, it should be noted the project GAMMA-400, developed in P. N. Lebedev Institute [10, 11], as one of the most competitive (energy resolution of 1%, angle resolution 0.01°). This gamma-ray telescope is a stack of silicon strips and scintillation plates, and a TeV quantum, passing through it, practically loses all its energy. The system of photomultipliers allows not only to determine the initial energy of the quantum, by summing photo responses, but also to identify the point of conversion and the direction of the incident photon with the help of fiberoptic cabling.

[10] M.Fradkin, L.Kurnosova, N.Topchiev et al., "Some tasks of observational gamma-ray astronomy in the energy range 5-400 GeV": Space Science Reviews. 49, 215-226 (1988).

[11] A.M.Galper, N.P.Topchiev et al. "Status of the GAMMA-400 Project". Advances in Space Research. 51 (2), 297-300, arXiv: 1507.06246, DOI: S1875389215013826, (2013).

2016-04

http://arxiv.org/abs/1604.00014

A review of indirect searches for particle dark matter

Jennifer M. Gaskins

The Earth's atmosphere is opaque to gamma rays, so to directly detect photons at these energies it is necessary to observe from space. The Fermi Large Area Telescope (LAT) [66, 67] is the primary instrument on the Fermi Gamma-ray Space Telescope, launched in June 2008. The LAT is a pair-production detector which consists of an array of modules that form the tracker and calorimeter, surrounded by an anti-coincidence detector for charged particle identification. Sensitive to gamma rays from ~ 20 MeV to more than 300 GeV, the LAT detects and reconstructs individual gamma-ray and charged-particle events, determining the arrival direction and energy of each event. It features a large field-of-view (~2.4 sr) and operates primarily in sky-scanning mode, enabling studies of sources all over the sky, including large-scale diffuse emission. The GAMMA-400 telescope, with a planned launch in 2019, will cover a similar energy range to the LAT but with improved angular and energy resolution [68].

[68] A. Moiseev, A. Galper, O. Adriani, R. Aptekar, I. Arkhangelskaja, et al., Dark Matter Search Perspectives with GAMMA-400, arXiv:1307.2345.

2016-03

http://arxiv.org/abs/1603.06978

Search for spectral irregularities due to photon-axion-like particle oscillations with the Fermi Large Area Telescope

M. Ajello et al. (Fermi collaboration)

Observations with future -ray instruments could improve the reported limits and test ALP DM models. The planned GAMMA-400 satellite, with an envisaged energy resolution of 1% above 10 GeV [63], might be able to better resolve the spectra and probe higher ALP masses. Higher masses could also be reached with the future Cherenkov Telescope Array (CTA) [64].

[63] P. Cumani, A. M. Galper, V. Bonvicini, et al., arXiv:1502.02976

2016-02

http://arxiv.org/abs/1602.02728

The future of gamma-ray astronomy

Jürgen Knödlseder

The Gamma Astronomical Multifunctional Modular Apparatus with the maximum gamma-ray energy of 400 GeV (GAMMA-400, see [72]) is a Russian-led project for building a next generation gamma-ray telescope optimized for energies around 100 GeV with the best possible angular and energy resolution and proton rejection factor [73]. Since the initial proposal that goes back to the late 1980ies the maximum target energy has been raised, and the current GAMMA-400 design will be sensitive to gamma rays in the 100 MeV - 3 TeV energy range.

[72] //gamma400.lebedev.ru/

[73] A. M. Galper, et al., in: 33rd International Cosmic Ray Conference (2013) arXiv:1306.6175

2016-01

http://arxiv.org/abs/1601.06590

Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies

M.L. Ahnen et al.

Our global analysis method is completely generic, and can be easily extended to include data from more targets, instruments and/or messenger particles provided they have similar sensitivity to the considered DM particle mass range. Of particular interest is the case of a global DM search from dSphs including data from all current gamma-ray (Fermi-LAT, MAGIC, H.E.S.S, VERITAS, HAWC) and neutrino (Antares, IceCube, SuperKamiokande) instruments, and we hereby propose a coordinated effort toward that end. Including results obtained from other types of observational targets like the Galactic Center, galaxy clusters or others is formally also possible, but a common approach to the J-factor determination remains an open question. In the future, this analysis could include new instruments like CTA [58], GAMMA-400 [59], DAMPE [60] or Km3Net [61].13 Our global approach offers the best chances for indirect DM discovery, or for setting the most stringent limits attainable by these kind of observations.

[59] A. A. Moiseev et al. Dark Matter Search Perspectives with GAMMA-400, in Proc. of the 33^rd International Cosmic-Ray Conference 2013, Brazil, Rio de Janeiro. [arXiv:1307.2345]

2016-01

http://arxiv.org/abs/1601.02920

(Very)-High-Energy Gamma-Ray Astrophysics: the Future

Alessandro De Angelis

3.2 The GeV region

It is difficult to think for this century of an instrument for GeV photons improving substantially the performance of the Fermi LAT: the cost of space missions is such that the size of Fermi cannot be reasonably overcome with present technologies. New satellites in construction (like the Russian-Italian mission GAMMA400 [13] and the Chinese mission HERD [14]) improve some of the aspects of Fermi, e.g., calorimetry. For sure a satellite in the GeV region with sensitivity comparable with Fermi will be needed.

[13] //gamma400.lebedev.ru/indexeng.html