Imprint of a 2 Myr old source on the cosmic ray anisotropy

We study numerically the anisotropy of the cosmic ray (CR) flux emitted by a single source calculating the trajectories of individual CRs. We show that the contribution of a single source to the observed anisotropy is instead determined solely by the fraction the source contributes to the total CR intensity, its age and its distance,and does not depend on the CR energy at late times. Therefore the observation of a constant dipole anisotropy indicates that a single source dominates the CR flux in the corresponding energy range. A natural explanation for the plateau between 2--20 TeV observed in the CR anisotropy is thus the presence of a single, nearby source. For the source age of 2 Myr, as suggested by the explanation of the antiproton and positron data from PAMELA and AMS-02 through a local source [arXiv:astro-ph/1504.06472], we determine the source distance as $\sim 200$ pc. Combined with the contribution of the global CR sea calculated in the escape model, we can explain qualitatively the data for the dipole anisotropy. Our results suggest that the assumption of a smooth CR source distribution should be abandoned between 200 GeV and 1 PeV.Comment: 4 pages, 4 eps figures; v2: minor changes, to appear in ApJ

Polar-bulge galaxies

Based on SDSS data, we have selected a sample of nine edge-on spiral galaxies with bulges whose major axes show a high inclination to the disk plane. Such objects are called polar-bulge galaxies. They are similar in their morphology to polar-ring galaxies, but the central objects in them have small size and low luminosity. We have performed a photometric analysis of the galaxies in the g and r bands and determined the main characteristics of their bulges and disks. We show that the disks of such galaxies are typical for the disks of spiral galaxies of late morphological types. The integrated characteristics of their bulges are similar to the parameters of normal bulges. The stellar disks of polar-bulge galaxies often show large-scale warps, which can be explained by their interaction with neighboring galaxies or external accretion from outside.Comment: 8 pages, 3 figure

Conductance of p-n-p graphene structures with 'air-bridge' top gates

We have fabricated graphene devices with a top gate separated from the graphene layer by an air gap--a design which does not decrease the mobility of charge carriers under the gate. This gate is used to realise p-n-p structures where the conducting properties of chiral carriers are studied. The band profile of the structures is calculated taking into account the specifics of the graphene density of states and is used to find the resistance of the p-n junctions expected for chiral carriers. We show that ballistic p-n junctions have larger resistance than diffusive ones. This is caused by suppressed transmission of chiral carriers at angles away from the normal to the junction.Comment: to be published in Nano Letter