Cosmic Gamma Rays Research Articles

Search for cosmic gamma rays of ultra-high energies with the Baksan air shower array

Recently two collaborations (Tibet ASγ and HAWC) almost simultaneously reported about their measurements of ultra-high-energy (> 100 TeV) gamma rays from the Crab Nebula. The Baksan air shower array (BASA) recorded a burst from this very source as long ago as more than 20 years. At the moment the new experiment on gamma ray astronomy (Carpet-3 project) started at Baksan, and it is appropriate to recall old results of BASA to be compared with the new results, already published and expected.

GRAINE Project, Precise Observations of High-energy Cosmic Gamma-rays with Balloon-borne Emulsion Telescope

GRAINE Project, Precise Observations of High-energy Cosmic Gamma-rays with Balloon-borne Emulsion Telescope

Cosmic gamma-ray spectrometer with tagged charged particles of Galactic Cosmic Rays

A new concept is proposed for the study of the elemental composition of planetary surfaces on landed missions through the coincident detection of gamma rays induced by Galactic Cosmic Ray (GCR) charged particles and the detection of the incident charged particle that produces the gamma ray. Charged particle detection is used to tag all instances of GCR interaction in a selected volume of the subsurface that results in the emission of secondary gamma rays. Using the criteria of a tagged GCR particle and coincident gamma ray detection, one may measure gamma ray spectra produced in a selected subsurface volume by GCR induced spallation and inelastic scattering of fast neutrons. The proposed new technique minimizes the contribution of gamma radiation from other regions of the subsurface and spacecraft structural components that may add background to the measured gamma-ray spectrum from the selected soil volume.

The Carpet-3 multipurpose shower array for searching cosmic diffuse gamma rays with energy Eγ > 100 TeV

An experiment for measuring the flux of cosmic gamma rays with energy above 100 TeV is currently being prepared at the Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences. At present the plastic scintillation counters with a total continuous area of 410 m2 are installed in the muon detector (MD) underground tunnels, and they are totally equipped with electronics. Six modules of shower detectors have been already placed on the surface of the MD absorber. In each of them 9 standard plastic scintillation counters are placed with an area of 1 m2 each. These modules are components of the ground surface part of Carpet-3 shower array. The data acquisition system for this array is almost ready. Expected flux limits for cosmic diffuse gamma rays of galactic origin in this work is close to existing experimental limits in the range lower than about 5 PeV, and with improved sensitivity of Carpet-3 one can hope to detect this flux or at least to obtain the best upper limit.

Indirect effects of dark matter

Here, we briefly review possible indirect effects of dark matter (DM) of the universe. It includes effects in cosmic rays (CR): first of all, the positron excess at [Formula: see text]500[Formula: see text]GeV and possible electron–positron excess at 1–1.5[Formula: see text]TeV. We tell that the main and least model-dependent constraint on such possible interpretation of CR effects goes from gamma-ray background. Even ordinary [Formula: see text] mode of DM decay or annihilation produces prompt photons (FSR) so much that it leads to contradiction with data on cosmic gamma-rays. We present our attempts to possibly avoid gamma-ray constraint. They concern with peculiarities of both space distribution of DM and their physics. The latter involves complications of decay/annihilation modes of DM, modifications of Lagrangian of DM-ordinary matter interaction and inclusion of mode with identical fermions in final state. In this way, no possibilities to suppress were found except, possibly, the mode with identical fermions. While the case of spatial distribution variation allows achieving consistency between different data. Also, we consider stable form of DM which can interact with baryons. We show which constraint such DM candidate can get from the damping effect in plasma during large-scale structure (LSS) formation in comparison with other existing constraints.

Development of a balloon-style pressure vessel gondola for balloon-borne emulsion gamma-ray telescopes

A gamma-ray telescope using nuclear emulsions allows observations of stellar objects in the 0.01–100 GeV energy region with high angular resolution, polarization sensitivity, and large aperture area. The Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE) project is designed to enable high-precision observation of cosmic gamma rays through the use of balloon-borne emulsion telescopes. We have developed a balloon-style pressure vessel gondola for the GRAINE 2018 balloon-borne experiment. It enables us to maintain robust and vacuum-packed emulsion chambers even at balloon altitudes. The greater part of the vessel is made of membrane materials consisting of ultra-thin polyurethane-coated polyester fabric. It is lightweight and portable, and can be used to expand the mounting area of the detector, unlike mostly metal vessels. Moreover, the absorption of signal gamma rays and background gamma-ray production due to interactions between cosmic rays and the vessel can be minimized. The pressure vessel gondola, equipped with a 0.38-m2 emulsion telescope and other equipment, was launched on April 26, 2018. During the whole observation (17 h 21 m), the internal pressure was kept above 230 hPa. The GRAINE project will start scientific observation using enlarged telescopes and the pressure vessel gondola is planned to include an expansion of the mounting area of the detector to ∼10 m2 while following the design on the GRAINE 2018 model.

The Upper Limit on Isotropic Flux of Diffuse Gamma Rays with Energy Above 700 TeV as Measured by the Carpet-2 Air Shower Array

An experiment for measuring the flux of cosmic diffuse gamma rays with energies higher than 100 TeV (the Carpet-3 project) is under preparation at the Baksan Neutrino Observatory. The experiment suggests to increase areas of both the muon detector and the surface shower detectors. The experiment’s sensitivity to the showers initiated by primary gamma rays is estimated in this paper for different configurations of the array. In addition, preliminary estimates of the upper limit on diffuse gamma rays with energy above 700 TeV are presented. They are derived from experimental data of the Carpet-2 array (previous version of the experiment) for the net exposure of 9.2 years of observation.

Eye On China

The following topics are under this section: Shanghai neurologists test brain implant to tackle drug addiction Bio-imaging breakthrough developed by China-Australia collaboration Gene-editing researchers reduce cancer risk Beijing Genomics Institute to invest in construction of the National Genome Science Data Centre DNA data storage becomes a top emerging technology Researchers find new gene linked to deafness Scientists discover highest energy cosmic gamma rays in Tibet China tightens rules on genetic research after rogue scientist He Jiankui's designer baby scandal First remote 5G breast cancer surgery a success Vaccine shortage hits many parts of China First China-Belgium Science and Technology Exchange Symposium held in Brussels

Gamma-ray astrophysics: roots, growth, and success

This short review outlines the historic roots of high-energy astronomy in the early twentieth century with the discovery of radioactivity, cosmic ray research, and the development of detectors to measure high-energy photons. The beginning of the space age in the 1960s provided the means to observe cosmic gamma rays unhindered by the absorption and local background inside Earth’s atmosphere. We describe the results from pioneering missions in the 1970s up to the first ‘golden age’ of gamma-ray astronomy in the 1990s with the Compton Gamma-Ray Observatory (CGRO). The focus in this review will be on gamma-ray astronomy in the pair creation energy band, above several 10’s of MeV.

Radiation chemistry in astrochemical models: From the laboratory to the ISM

AbstractMost interstellar and planetary environments are suffused by a continuous flux of several types of ionizing radiation, including cosmic rays, stellar winds, x-rays, and gamma-rays from radionuclide decay. There is now a large body of experimental work showing that these kinds of radiation can trigger significant physicochemical changes in ices, including the dissociation of species (radiolysis), sputtering of surface species, and ice heating. Even so, modeling the chemical effects that result from interactions between ionizing radiation and interstellar dust grain ice mantles has proven challenging due to the complexity and variety of the underlying physical processes. To address this shortcoming, we have developed a method whereby such effects could easily be included in standard rate-equations-based astrochemical models. Here, we describe how such models, thus improved, can fruitfully be used to simulate experiments in order to better understand bulk chemistry at low temperatures.

Search for simultaneous and parallel cosmic gamma rays in the balloon-borne emulsion telescope experiments (GRAINE2015)

The emulsion chamber telescopes for observing 10 MeV - 100 GeV gamma rays have been developed by GRAINE (Gamma Ray Astro-Imager with Nuclear Emulsion) projects. We have performed the balloon filight in May, 2015 at Alice Springs, Australia, with 14.4 hours duration (including 11.5 hours of level flight) and 0.378 square meter aperture (GRAINE2015). GRAINE experiments utilized the multiple stage systems of emulsion films for timestamper of registered tracks.In this paper, we report the potential of GRAINE2015 experiments to detect the parallel and simultaneous cosmic gamma rays such as charged particles due to hadronic interactions, EAS (Extensive Air Shower) and GRBs (Gamma Ray Bursts).

Direct and Indirect Probes for Composite Dark Matter

Dark matter candidates are one of the profound signatures of new physics, reflecting existence of new stable particles. If such particles are charged they can bind with ordinary electrons, forming anomalous isotopes. Severe constraints on the anomalous hydrogen exclude new stable single charged particles, but the case of stable double charged particles is not excluded so easily. Similar to ordinary baryonic matter dark matter candidates can be in the form of neutral dark atoms in which new stable or sufficiently long living double charged particles are bound by ordinary Coulomb interaction. In the most simple case only negative double charged particles are bound in O-helium (OHe) dark atoms with primordial helium. OHe hypothesis can provide the solution for puzzles of direct dark matter searches by specifics of OHe interaction in the matter of underground detectors. OHe interaction in the matter can lead to formation of various exotic forms of O-nuclearities. Provided that the mass of the double charged particle is around 1.25 TeV OHe hypothesis can explain the observed positron annihilation line excess in the galactic bulge by pair production in de-excitation of OHe atoms colliding in this region. In the model of Walking Technicolor generation of primordial excess of negatively charged techniparticles (over their antiparticles) can be related to the baryon asymmetry of the Universe, giving proper relationship of baryonic and non-baryonic matter densities. Such primordial excess may be accompanied by a subdominant excess of longliving positively double charged techniparticles, whose decay to same sign pair of leptons can explain the high energy cosmic positron anomaly, detected by PAMELA and AMS02. This explanation should be confronted with the cosmic gamma ray background measured by FERMI/LAT, what put upper limit on the mass of a decaying double charged particle. It makes search for stable double charged particles at the LHC a direct probe for composite dark matter hypothesis.

The GRAND project and GRANDProto300 experiment

The Giant Array for Neutrino Detection (GRAND) is a proposal for a giant observatory of ultra-high energy cosmic particles (neutrinos, cosmic rays and gamma rays). It will be composed of twenty subarrays of 10 000 antennas each, totaling a detection area of 200 000 km2. GRAND will reach unprecedented sensitivity to neutrinos allowing to detect cosmogenic neutrinos while its sub-degree angular resolution will also make it possible to hunt for point sources and possibly start neutrino astronomy. Combined with its gigantic exposure to ultra-high energy cosmic rays and gamma rays, GRAND will be a powerful tool to solve the century-long mistery of the nature and origin of the particles with highest energy in the Universe. On the path to GRAND, the GRANDProto300 experiment will be deployed in 2020 over a total area of 200 km2. It primarly aims at validating the detection concept of GRAND, but also proposes a rich science program centered on a precise and complete measurement of the air showers initiated by cosmic rays with energies between 1016.5and 1018eV, a range where we expect to observe the transition between the Galactic and extra-galactic origin of cosmic rays.

Radio detection in the multi-messenger context

The present work discusses the development of the radio technique for detection of ultra-high energy air-showers induced by cosmic radiation, and the prospects of its application in the future multi-messenger activities, particularly for detection of ultra-high energy cosmic rays, gamma rays and neutrinos. It gives an overview of the results achieved by the modern digital radio arrays, as well as discuss present challenges and future prospects.

GRAINE project: precise gamma-ray observations with balloon-borne emulsion telescope

Observation of cosmic gamma rays is important in the understanding of high-energy objects or phenomena in the universe. Since 2008, the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope (Fermi-LAT) has surveyed the sub-GeV/GeV gamma-ray sky and achieved high statistics measurements. However, observation at low galactic latitudes remains difficult owing to the lack of angular resolution, and new issues following the operation of Fermi-LAT have arisen. We devised a precise gamma-ray observation project, Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE), using balloon-borne emulsion gammaray telescopes to realize high angular resolution, polarization-sensitive, and large-aperture observations in the 10 MeV–100 GeV energy region. Following basic developments on the ground, we performed three balloon-borne experiments with upgraded instruments. In this paper, we present results from the second balloon experiment in 2015, a report on the latest balloon experiment conducted on April 26, 2018, and a recent study on hadronic interactions using proton beams.

Towards A Next Generation of CORSIKA: A Framework for the Simulation of Particle Cascades in Astroparticle Physics

A large scientific community depends on the precise modeling of complex processes in particle cascades in various types of matter. These models are used most prevalently in cosmic ray physics, astrophysical-neutrino physics, and gamma ray astronomy. In this white paper, we summarize the necessary steps to ensure the evolution and future availability of optimal simulation tools. The purpose of this document is not to act as a strict blueprint for next-generation software, but to provide guidance for the vital aspects of its design. The topics considered here are driven by physics and scientific applications. Furthermore, the main consequences of implementation decisions on performance are outlined. We highlight the computational performance as an important aspect guiding the design, since future scientific applications will heavily depend on an efficient use of computational resources.

Extragalactic gamma-ray background from star-forming galaxies: Will empirical scalings suffice?

Despite the influx of unprecedented-quality data from the Fermi Gamma-Ray Space Telescope that have been collected over nine years of operation, the contribution of normal star-forming galaxies to the extragalactic gamma-ray background (EGRB) remains poorly constrained. Different estimates are discrepant both their underlying physical assumptions and their results. With several detections and many upper limits for the gamma-ray fluxes of nearby starforming galaxies now available, estimates that rely on empirical scalings between gamma-ray and longer-wavelength luminosities have become possible and increasingly popular. In this paper we examine factors that can bias such estimates, including: a) possible sources of nontrivial redshift dependence; b) dependence on the choice of star-formation tracer; c) uncertainties in the slope and normalisation of empirical scalings. We find that such biases can be significant, pointing towards the need for more sophisticated models for the star-forming galaxy contribution to the gamma-ray background, implementing more, and more confident, physics in their buildup. Finally, we show that there are large regions of acceptable parameter space in observational inputs that significantly overproduce the gamma-ray background, implying that the observed level of the background can yield significant constraints on models of the average cosmic gamma-ray emissivity associated with star formation.

Detection of UV Radiation from Extensive Air Showers: Prospects for Cherenkov Gamma-Ray Astronomy

Cherenkov emission of extensive air showers (EAS) from cosmic gamma rays and cosmic-ray protons has been modelled. Spectral density of such emission in the 240–700 nm band has been determined for 3 GeV–10 TeV primaries of both sorts. It has been shown that the ratio of EAS Cherenkov emission fluxes in the optical and ultraviolet (UV) bands substantially depends on the sort of the primary, so the ratio can be employed to select gamma-ray events from the background produced by cosmic rays. Detection of EAS Cherenkov emission with specialized silicon photomultipliers sensitive in the UV band would allow one to substantially extend the duty cycle of a Cherenkov gamma-ray telescope, as it would be possible to observe the showers during moonlit nights. The UV-sensitive silicon photomultipliers developed at the Ioffe Institute would allow to detect gamma-ray-induced EAS at the Cherenkov gamma-ray observatory ALEGRO over a threshold of about 40 GeV at 5 km above sea level and about 80 GeV at 2 km above sea level.

Study of Thin Double-Gap RPCs for the CMS Muon System

High-sensitivity double-gap phenolic resistive plate chambers (RPCs) are studied for the Phase-2 upgrade of the Compact Muon Solenoid (CMS) muon system at high pseudorapidity η. Whereas the present CMS RPCs have a gas gap thickness of 2 mm, we propose to use thinner gas gaps, which will improve the performance of these RPCs. To validate this proposal, we constructed double-gap RPCs with two different gap thicknesses of 1.2 and 1.4 mm by using high-pressure laminated plates having a mean resistivity of about 5 × 1010 Ω-cm. This paper presents test results using cosmic muons and 137Cs gamma rays. The rate capabilities of these thin-gap RPCs measured with the gamma source exceed the maximum rate expected in the new high-η endcap RPCs planned for future Phase-2 runs of the Large Hadron Collider (LHC).

DAMPE excess from decaying right-handed neutrino dark matter

The flux of high-energy cosmic-ray electrons plus positrons recently measured by the DArk Matter Particle Explorer (DAMPE) exhibits a tentative peak excess at an energy of around 1.4 TeV. In this paper, we consider the minimal gauged U(1)[Formula: see text] model with a right-handed neutrino (RHN) dark matter (DM) and interpret the DAMPE peak with a late-time decay of the RHN DM into [Formula: see text]. We find that a DM lifetime [Formula: see text] can fit the DAMPE peak with a DM mass [Formula: see text]. This favored lifetime is close to the current bound on it by Fermi-LAT, our decaying RHN DM can be tested, once the measurement of cosmic gamma ray flux is improved. The RHN DM communicates with the Standard Model particles through the U(1)[Formula: see text] gauge boson ([Formula: see text] boson), and its thermal relic abundance is controlled by only three free parameters: [Formula: see text], the U(1)[Formula: see text] gauge coupling [Formula: see text], and the [Formula: see text] boson mass [Formula: see text]. For [Formula: see text], the rest of the parameters are restricted to be [Formula: see text] and [Formula: see text], in order to reproduce the observed DM relic density and to avoid the Landau pole for running [Formula: see text] below the Planck scale. This allowed region will be tested by the search for a [Formula: see text] boson resonance at the future Large Hadron Collider.