P. Tinyakov

DERIVING THE GLOBAL STRUCTURE OF THE GALACTIC MAGNETIC FIELD FROM FARADAY ROTATION MEASURES OF EXTRAGALACTIC SOURCES

We made use of the two latest sets of rotational measures (RMs) of extra-galactic radio sources, namely the NRAO VLA Sky Survey rotation measures catalog, and a compilation by Kronberg and Newton-McGee, to infer the global structure of the Galactic magnetic field (GMF). We have checked that these two data sets are mutually consistent. Given the existence of clear patterns in all-sky RM distribution we considered GMF models consisting of two components: disk (spiral or ring) and halo. The parameters of these components were determined by fitting different model field geometries to the observed RMs. We found that the model consisting of a symmetric (with respect to the Galactic plane) spiral disk and anti-symmetric halo fits the data best and reproduces the observed distribution of RMs over the sky very well. We confirm that ring disk models are disfavored. Our results favor small pitch angles around ∼ −5 ◦ and an increased vertical scale of electron distribution, in agreement with some recent studies. Based on our fits, we select two benchmark models suitable for studies of cosmic ray propagation, including the ultra-high energies. Subject headings: Galaxy: structure –ISM: magnetic fields– methods: data analysis

BL Lacertae are sources of the observed ultrahigh-energy cosmic rays

We calculate an angular correlation function between ultrahigh energy cosmic rays (UHECR), observed by Yakutsk and AGASA experiments, and the most powerful BL Lacertae objects. We find significant correlations with the probability of statistical fluctuation less than 10−4, including penalty for selecting the subset of the brightest BL Lacs. We conclude that some of the BL Lacs are sources of the observed UHECR and present a list of the most probable candidates.

Experimental signatures of supersymmetric dark-matter Q-balls

Theories with low-energy supersymmetry predict the existence of stable nontopological solitons,

Tracing protons through the Galactic magnetic field: a clue for charge composition of ultra-high-energy cosmic rays

Q\ensuremath{-}\mathrm{balls}

Correlation function of ultrahigh-energy cosmic rays favors point sources

, that can contribute to dark matter. We discuss the experimental signatures, methods of detection, and the present limits on such dark-matter candidates.

Excluding Light Asymmetric Bosonic Dark Matter

Abstract We reconstruct the trajectories of ultra-high-energy cosmic rays (UHECR)––observed by the AGASA experiment––in the Galactic magnetic field assuming that all particles have the same charge. We then study correlations between the reconstructed events and BL Lacertae (BL Lacs). The correlations have significance below 10−3 in the case of particles with charge +1. In the case of charge −1 the correlations are absent. We interpret this as evidence that protons are present in the flux of UHECR. Observed correlation provides an independent evidence that BL Lacs emit UHECR.

Testing the correlations between ultrahigh-energy cosmic rays and BL Lac-type objects with HiRes stereoscopic data

We calculate the angular two-point correlation function of ultrahigh-energy cosmic rays (UHECR) observed in the AGASA and Yakutsk experiments. In both data sets, there is a strong signal at the highest energies, which is concentrated in the first bin of size equal to the angular resolution of the experiment. For the uniform distribution of sources, the probability of chance clustering is 4×10−6. Correlations are absent or insignificant at larger angles. This favors the models with compact sources of UHECR

On the correlation of the highest-energy cosmic rays with nearby extragalactic objects reported by the Pierre Auger Collaboration

We argue that current neutron star observations exclude asymmetric bosonic noninteracting dark matter in the range from 2 keV to 16 GeV, including the 5-15 GeV range favored by DAMA and CoGeNT. If bosonic weakly interacting massive particles (WIMPs) are composite of fermions, the same limits apply provided the compositeness scale is higher than ∼10¹²  GeV (for WIMP mass ∼1  GeV). In the case of repulsive self-interactions, we exclude the large range of WIMP masses and interaction cross sections which complements the constraints imposed by observations of the Bullet Cluster.

Constraints on primordial black holes as dark matter candidates from capture by neutron stars

Previously suggested correlations of BL Lac-type objects with the arrival directions of the ultrahigh-energy cosmic ray primaries are tested by making use of the HiRes stereoscopic data. The results of the study support the conclusion that BL Lacs may be cosmic ray sources and suggest the presence of a small (a few percent) fraction of neutral primaries at E > 1019 eV.

Evidence for a Connection between the γ-Ray and the Highest Energy Cosmic-Ray Emissions by BL Lacertae Objects

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.We argue that the data published by the Pierre Auger Collaboration [1] disfavors, at the 99% confidence level, their hypothesis that most of the highest-energy cosmic rays are protons from nearby astrophysical sources—either active galactic nuclei or other objects with a similar spatial distribution.We argue that the data published by the Pierre Auger Collaboration (arXiv:0711.2256) disfavor at 99% confidence level their hypothesis that most of the highest-energy cosmic rays are protons from nearby astrophysical sources, either Active Galactic Nuclei or other objects with a similar spatial distribution.