Antiparticles account for a small fraction of cosmic rays and are known to be produced in interactions between cosmic-ray nuclei and atoms in the interstellar medium, which is referred to as a ...'secondary source'. Positrons might also originate in objects such as pulsars and microquasars or through dark matter annihilation, which would be 'primary sources'. Previous statistically limited measurements of the ratio of positron and electron fluxes have been interpreted as evidence for a primary source for the positrons, as has an increase in the total electron+positron flux at energies between 300 and 600 GeV (ref. 8). Here we report a measurement of the positron fraction in the energy range 1.5-100 GeV. We find that the positron fraction increases sharply over much of that range, in a way that appears to be completely inconsistent with secondary sources. We therefore conclude that a primary source, be it an astrophysical object or dark matter annihilation, is necessary.
Precise time-dependent measurements of the Z = 2 component in the cosmic radiation provide crucial information about the propagation of charged particles through the heliosphere. The PAMELA ...experiment, with its long flight duration (2006 June 15-2016 January 23) and the low energy threshold (80 MeV/n) is an ideal detector for cosmic-ray solar modulation studies. In this paper, the helium nuclei spectra measured by the PAMELA instrument from 2006 July to 2009 December over a Carrington rotation time basis are presented. A state-of-the-art three-dimensional model for cosmic-ray propagation inside the heliosphere was used to interpret the time-dependent measured fluxes. Proton-to-helium flux ratio time profiles at various rigidities are also presented in order to study any features that could result from the different masses and local interstellar spectra shapes.
The presence of dual structure in 13 clusters of galaxies from CfA2 Redshift Survey is discussed. The spatial distributions of galaxies and ones on absolute magnitude, luminosity, angular velocity ...and absolute magnitude, velocity and distance for cluster center reveal two areas for clusters nos. 88, 1101, 1046, 142, 933, 1242, 1652, 107, 150, 316, 317, 961, 977. The occurrence of such structure allows concluding two alternatives. In the first one dark matter presence inside cluster or their nearest neighborhoods in configuration similar to Zeldovich pancake. The second case is gravitational lensing on compact object or dark matter blob located between galaxy cluster and observer. But now several evidences against gravitational lensing were found. Firstly, the studying of Summary of Multiply Imaged Systems within CfA-Arizona Space Telescope LEns Survey of gravitational lenses gives minimum lens redshift
and maximum distance between images
arcsec. These values are in contradiction with parameters of analyzable clusters of galaxies. Maximum redshift of these clusters is 0.032, and maximum distances between galaxies reach several degrees. Secondly, the parts of dual structure of systems being studied contain sufficiently different number of spiral galaxies, but types of objects on images due lens should be similar. Then we have investigated these systems dynamic using Nonlinear Time Series Analysis. We have constructed phase space for such clusters of galaxies using values of redshift, coordinates, magnitude, absolute magnitude and distance to centre. As a timelike variable we supposed the ratio between galaxies’ tangential velocity and its distance to cluster’s centre. According to preliminary results of analysis we have obtained two attractors in the phase spaces of cluster nos. 88 and 142 with basins corresponding to bifurcation points on the analyzable distributions. Such results conclude real dual structure of systems being studied. Also, we have investigated the appearances of systems being analyzed in high-energy gamma bands. It was found that cluster nos. 933, 142, 1046, 1652 and 316 reveal high-energy
-associations on Fermi/LAT 12-Year Point Source Catalog 4FGL-DR3 (4FGL J1144.9
1937, 4FGL J0152.2
3714, 4FGL J1230.8
1223, 4FGL J1653.8
3945 and 4FGL J0708.9
4839). Moreover, sources 4FGLJ1144.9
1937, 4FGLJ1230.8
1223 and 4FGL J1653.8
3945 were registered in subTeV energy region by VERITAS. These objects should be jointly observed by ground-based Cherenkov air-shower experiments and orbital gamma-ray observatories with high angular and energy resolution better than Fermi/LAT. One of such planned orbital experiments is GAMMA-400 with angular and energy resolution
and
at
GeV and ability of registration of gamma-quanta up to several TeV. Also, the coordination of lists of multiwavelength observations of Cherenkov Telescope Array (CTA) and GAMMA-400 is discussed now. Such observations could clarify the properties of high-energy emission from 4FGL J1144.9
1937, 4FGL J1230.8
1223 and 4FGL J1653.8
3945 and its interrelation with the cluster nos. 933, 1046 and 1652.
Abstract
Time-dependent energy spectra of galactic cosmic rays (GCRs) carry fundamental information regarding their origin and propagation. When observed at the Earth, these spectra are significantly ...affected by the solar wind and the embedded solar magnetic field that permeates the heliosphere, changing significantly over an 11 yr solar cycle. Energy spectra of GCRs measured during different epochs of solar activity provide crucial information for a thorough understanding of solar and heliospheric phenomena. The PAMELA experiment collected data for almost 10 years (2006 June 15–2016 January 23), including the minimum phase of solar cycle 23 and the maximum phase of solar cycle 24. In this paper, we present new spectra for helium nuclei measured by the PAMELA instrument from 2010 January to 2014 September over a three-Carrington-rotation time basis. These data are compared to the PAMELA spectra measured during the previous solar minimum, providing a picture of the time dependence of the helium-nuclei fluxes over a nearly full solar cycle. Time and rigidity dependencies are observed in the proton-to-helium flux ratios. The force-field approximation of the solar modulation was used to relate these dependencies to the shapes of the local interstellar proton and helium-nuclei spectra.
Cosmophysical Research with GAMMA-400 Topchiev, N. P.; Galper, A. M.; Arkhangelskaja, I. V. ...
Physics of atomic nuclei,
08/2023, Letnik:
86, Številka:
4
Journal Article
Recenzirano
The GAMMA-400 gamma-ray telescope is the successor of Soviet and Russian gamma-ray telescopes. GAMMA-400 is being developed for cosmophysical research in accordance with the Russian Federal Space ...Program 2016–2025. The GAMMA-400 experiment will be implemented aboard the Russian astrophysical space observatory in a highly elliptic orbit during 7 years to provide new data on gamma-ray emission mainly from the Galactic plane, Galactic Center, the Sun and cosmic-ray electron
positron fluxes. The main mode of observations will be the continuous point-source mode with the duration of up to
100 days. The GAMMA-400 gamma-ray telescope will study high-energy gamma-ray emission up to several TeV and cosmic-ray electrons
positrons up to 20 TeV. GAMMA-400 will have the never-achieved angular resolution, the high-energy and time resolutions, as well as very good separation efficiency of gamma rays from cosmic-ray background and of electrons
positrons from protons. The distinctive features of GAMMA-400 are the excellent angular resolution of
at
GeV that exceeds resolutions of the space-based and ground-based gamma-ray telescopes by a factor of 5–10, as well as high-energy resolution of
at
GeV. GAMMA-400 studies can discover gamma-ray emission from annihilation or decay of dark matter particles, identify many unassociated discrete sources, explore the structure of extended sources, search for gamma-ray bursts and solar gamma-ray flares, improve the data on cosmic-ray electron
positron spectra for energies of >50 GeV.
Preliminary results of the investigation of the characteristics of 5 groups of galaxies are discussed in the presented article. We have analyzed the main characteristics of galaxy clusters 933, 88, ...142, 1046, 1101 from CfA2 redshift survey. Clusters 933, 142, 1046, and 1652 have high-energy gamma associations on Fermi/LAT data (4FGL J1144.9
1937, 4FGL J0152.2
3714, 4FGL J1230.8
1223 and 4FGL J1653.8
3945). These sources are active galaxies. Furthermore, the radiogalaxy 3C 264 (4FGL J1144.9
1937) was previously observed in the energy band
TeV. We have found several anomalies of the spatial dynamics of galaxies in these clusters. These features could be caused by the dynamics of galaxies’ motion in a gravitationally bound group taking into account possible space–time inhomogeneities at large distances. Investigation of high-energy gamma-emission of galaxies and peculiarities of its motion in groups allows studying properties of such inhomogeneities and understanding of its nature possibly caused by dark matter. The investigation of the spatial distribution and other characteristics of 933, 88, 142, 1046, 1101 galaxy clusters shows gravitational lensing effect. But now it is unknown which objects are gravitational lenses for these clusters. The angular size of such clusters is about 1–2 degree and now there are not clear associations between group members of clusters 142, 1046, and 1652 with the high-energy gamma-sources 4FGL J0152.2
3714, 4FGL J1230.8
1223, and 4FGL J1653.8
3945. Common observations of such clusters by orbital gamma-ray observatories with high angular resolution and ground-based Cherenkov air-shower experiments could possibly clarify the type of gravitational lenses.
Introduction:
Breast cancer patients and survivors frequently report fatigue, emotional, and cognitive disturbances, which reduce performance at all levels of occupation and make life quality issues ...a considerable clinical concern. The aim of this study is to evaluate attention and emotion regulation across radiotherapy period and the possible effects of complementary alternative medicine (CAM).
Methods:
Fifty-seven patients with unilateral breast cancer underwent surgery and systemic chemotherapy before participating in this double-blind randomized study. Two thirds were given CAM (n = 38) while the rest received placebo (carrier only, n = 19). Patients’ attention and anxiety were physiologically tested at baseline, 2 and 4 weeks during the radiation period as well as 1-month after the end of radiation session.
Results:
Both groups showed similar levels of anxiety with no significant differences at baseline nor post-radiotherapy. Long-term significant recovery of attention performance was observed in the CAM patients, accompanied by a similar tendency in anxiety level, measured by the eye-blink probability.
Conclusions:
This study physiologically validates the attention impairment reported among breast cancer survivors; also, it depicted a beneficial late-effect of a routine CAM on attention dysregulation. The suggested non-invasive physiological measures can physiologically monitor patients’ psychological and cognitive well-being as well as evaluate the beneficial effect of CAM in breast cancer patients by assessing their coping ability to support the treatment plan. Thus, the results have potential clinical implications on patients’ and survivors’ quality of life.
Trial Registration:
NIH, NCT02890316. Registered July 2016, http://www.ClinicalTrials.gov
A Forbush decrease (FD) is a sudden drop of cosmic-ray intensity arising as an effect of coronal mass ejection (CME) propagation in interplanetary space. The different physical properties of each CME ...cause variability in the FDs observed by scientific instruments. A comprehensive study of both phenomena is required to properly understand the processes involved in FDs. Most of the current studies in this field use experimental data obtained by ground-based apparatus that measure the flux of cosmic rays via their interaction with Earth’s atmosphere. Direct measurements in space of FDs are rather rare. In this work, we present the results obtained by the spacecraft-borne experiment
Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics
(PAMELA). The experiment took data from 15 June 2006 until January 2016. A series of FDs during the period 2006 – 2013 were studied. Only significant events with amplitude ≥ 10% for the proton flux
R
=
1.1
– 2.9 GV were taken into account. The dependencies of the recovery times on the particle rigidity were obtained for FD events generated by halo-type CMEs.
The future space-based GAMMA-400
-ray telescope will operate onboard the Russian astrophysical observatory in a highly elliptic orbit during 7 years. Observing
-ray sources from Galactic plane,
-ray ...bursts,
-ray diffuse emission,
rays from the Sun, and
rays from dark matter particles will be performed uninterruptedly for a long time (
100 days) in point-source mode in contrast to scanning mode for Fermi-LAT and other space- and ground-based instruments. GAMMA-400 will measure
rays in the energy range from
20 MeV to several TeV units, have the unprecedented angular (
at
GeV) and energy (
at
GeV) resolutions better than for Fermi-LAT, as well as ground-based
-ray facilities, by a factor of 5–10, and perfectly separate
rays from cosmic-ray background.
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