[en] We study the masses and radii of 65 exoplanets smaller than 4 R _⊕ with orbital periods shorter than 100 days. We calculate the weighted mean densities of planets in bins of 0.5 R _⊕ and identify a density maximum of 7.6  g cm^–3 at 1.4 R _⊕. On average, planets with radii up to R _P = 1.5 R _⊕ increase in density with increasing radius. Above 1.5 R _⊕, the average planet density rapidly decreases with increasing radius, indicating that these planets have a large fraction of volatiles by volume overlying a rocky core. Including the solar system terrestrial planets with the exoplanets below 1.5 R _⊕, we find ρ_P = 2.43 + 3.39(R _P/R _⊕) g cm^–3 for R _P < 1.5 R _⊕, which is consistent with rocky compositions. For 1.5 ≤ R _P/R _⊕ < 4, we find M _P/M _⊕ = 2.69(R _P/R _⊕)^0.93. The rms of planet masses to the fit between 1.5 and 4 R _⊕ is 4.3 M _⊕ with reduced χ² = 6.2. The large scatter indicates a diversity in planet composition at a given radius. The compositional diversity can be due to planets of a given volume (as determined by their large H/He envelopes) containing rocky cores of different masses or compositions

[en] The state of the surface of mesh implants and their encapsulation region in herniology is investigated by laser confocal microscopy. A correlation between the probability of developing relapses and the size and density of implant microdefects is experimentally shown. The applicability limits of differential reverse scattering for monitoring the post-operation state of implant and adjacent tissues are established based on model numerical experiments. (optical technologies in biophysics and medicine)

[en] A counter-streaming flow system is a test-bed to investigate the astrophysical collisionless shock (CS) formation in the laboratory. Electrostatic/electromagnetic instabilities, competitively growing in the system and exciting the CS formation, are sensitive to the flows parameters. One of the most important parameters is the velocity, determining what kind of instability contributes to the shock formation. Here we successfully measure the evolution of the counter-streaming flows within one shot using a multi-pulses imaging diagnostic technique. With the technique, the average velocity of the high-density-part ($n_{\mathrm{e}}\ge <!--\; ???\; -->8-<!--\; ???\; -->9\times <!--\; ??\; -->{10}^{19}\mathrm{c}{\mathrm{m}}^{-<!--\; ???\; -->3}$) of the flow is directly measured to be of $\sim <!--\; ???\; -->{10}^6$ cm/s between 7 ns and 17 ns. Meanwhile, the average velocity of the low-density-part ($n_{\mathrm{e}}\le <!--\; ???\; -->2\times <!--\; ??\; -->{10}^{19}\mathrm{c}{\mathrm{m}}^{-<!--\; ???\; -->3}$) can be estimated as $\sim <!--\; ???\; -->{10}^7$cm/s. The experimental results show that a collisionless shock is formed during the low-density-part of the flow interacting with each other. (paper)

[en] The detection of gravitational waves from the merger of binary black holes by the LIGO Collaboration has opened a new window to astrophysics. With the sensitivities of ground based detectors in the coming years, we will principally detect local binary black hole mergers. The integrated merger rate can instead be probed by the gravitational-wave background, the incoherent superposition of the released energy in gravitational waves during binary-black-hole coalescence. Through that, the properties of the binary black holes can be studied. In this work we show that by measuring the energy density Ω_GW (in units of the cosmic critical density) of the gravitational-wave background, we can search for the rare ∼ 100 M _⊙ massive black holes formed in the Universe. In addition, we can answer how often the least massive BHs of mass ≳ 3 M _⊙ form. Finally, if there are multiple channels for the formation of binary black holes and if any of them predicts a narrow mass range for the black holes, then the total Ω_GW spectrum may have features that with the future Einstein Telescope can be detected.

[en] The subject of this paper is the design of practical laser experiments that can produce collisionless shocks mediated by the Weibel instability. Such shocks may be important in a wide range of astrophysical systems. Three issues are considered. The first issue is the implications of the fact that such experiments will produce expanding flows that are approximately homologous. As a result, both the velocity and the density of the interpenetrating plasma streams will be time dependent. The second issue is the implications of the linear theory of the Weibel instability. For the experiments, the instability is in a regime where standard simplifications do not apply. It appears feasible but non-trivial to obtain adequate growth. The third issue is collisionality. The need to keep resistive magnetic-field dissipation small enough implies that the plasmas should not be allowed to cool substantially.

[en] Standard perturbation theory (SPT) for large-scale matter inhomogeneities is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small on all scales; it does not fully account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV-divergent, making predictions cutoff dependent and hence unphysical. The Effective Field Theory of Large Scale Structures successfully addresses all three issues. Here we focus on the third one and show explicitly that the terms induced by integrating out short scales, neglected in SPT, have exactly the right scale dependence to cancel all UV-divergences at one loop, and this should hold at all loops. A particularly clear example is an Einstein deSitter universe with no-scale initial conditions P_in ∼ kⁿ. After renormalizing the theory, we use self-similarity to derive a very simple result for the final power spectrum for any n, excluding two-loop corrections and higher. We show how the relative importance of different corrections depends on n. For n ∼ −1.5, relevant for our universe, pressure and dissipative corrections are more important than the two-loop corrections

[en] The light curves of V X Cas, V V and D D are studied in Institute of Astrophysics of the Academy of Science of the Republic of Tajikistan for 40-50 years on the photographic observations. It is established, that the reason of light changes of these variables is existence around of them about 100000 dust clouds, eclipsing these stars from time to time

[en] Experimentally distinguishing different primordial universe paradigms that lead to the Big Bang model is an outstanding challenge in modern cosmology and astrophysics. We show that a generic type of signals that exist in primordial universe models can be used for such purpose. These signals are induced by tiny oscillations of massive fields and manifest as features in primordial density perturbations. They are capable of recording the time-dependence of the scale factor of the primordial universe, and therefore provide direct evidence for specific paradigm. These signals present special opportunities and challenges for experiments and data analyses.

[en] We consider a scenario in which primordial scalar perturbations are generated when complex conformal scalar field rolls down its negative quartic potential. Initially, these are the perturbations of the phase of this field; they are converted into the adiabatic perturbations at a later stage. A potentially dangerous feature of this scenario is the existence of perturbations in the radial field direction, which have red power spectrum. We show, however, that to the linear order in the small parameter — the quartic self-coupling — the infrared effects are completely harmless, as they can be absorbed into field redefinition. We then evaluate the statistical anisotropy inherent in the model due to the existence of the long-ranged radial perturbations. To the linear order in the quartic self-coupling the statistical anisotropy is free of the infrared effects. The latter show up at the quadratic order in the self-coupling and result in the mild (logarithmic) enhancement of the corresponding contribution to the statistical anisotropy. The resulting statistical anisotropy is a combination of a larger term which, however, decays as momentum increases, and a smaller term which is independent of momentum

[en] We searched the Sloan Digital Sky Survey for outer halo globular clusters (GCs) around M31. Our search of non-stellar objects, within the limits of 0.3 ≤ (g – i)₀ ≤ 1.5 and 14.0 ≤ r₀ ≤ 19.0 concentrated in some remote areas of the extended halo, to a maximum projected distance of 240 kpc, for a total of approximately 200 deg². Another ∼50 deg², ∼5-75 kpc from M31, were surveyed as test areas. In these areas, we identified 39 GCs and 2 GC candidates, 84% of the previously known GCs (93% of the 'classical GCs' and 40% of the 'halo extended clusters', on the cluster classification scheme of Huxor et al.). For the entire survey, we visually inspected 78,516 objects for morphological evidence of cluster status, and we identified 18 new clusters, and 75 candidate clusters. The new clusters include 15 classical globulars and 3 clusters of lower density. Six of the clusters reside in the remote areas of the outer halo, beyond projected distances of 100 kpc. Previously, only MGC1 was found beyond this limit at 117 kpc. The farthest cluster discovered in this survey lies at a projected radius of 158 kpc from M31, assuming that the M31 distance is 780 kpc.