The signature of superstring balls near mini black holes at LHC

In this paper the information loss for fermionic superstrings “superstring balls” in mini black holes at LHC by extending the Gottesman and Preskill method to string theory and calculate the information transformation from the collapsing matter to the state of outgoing Hawking radiation is calculated. It is found that for all finite values of ω _n , all information from all string emission processes experiences some degree of loss. It means that the string model is not sufficient to solve the information-loss problem. Then the fermionic superstring states at corresponding point are considered. The correspondence principle offered a unique opportunity to test the Horowitz and Maldacena mechanism at correspondence point “the centre of mass energies around (M _s /(g _s )²)”. To consider the super string states, a copy of the original Hilbert space is constructed with a set of operators of creation/annihilation that have the same anticommutation properties as the original ones. The total Hilbert space is the tensor product of the two spaces H _physical ?H _unphysical , where in this case H _physical denotes the physical quantum states space of the fermionic string. It is shown that fermionic string states can be represented by a maximally entangled two-mode squeezed state of the physical and unphysical spaces of fermionic string. Also, the entropy for these string states is calculated. It is observed that black hole entropy matches the fermionic superstring entropy at transition point. This means that our result is consistent with correspondence principle and thus HM mechanism in string theory works. Finally the signature of fermionic string ball at LHC is studied. When superstring balls produce at LHC, they evaporate to Massive particles like Higgs boson. In fact string balls act as a factory for Higgs production. Then Higgs bosons decay to QCD matter. Thus an enhancement of QCD matter can be a signature of fermionic superstring ball at LHC.     

Imaging bright-spots in the accretion flow near the black hole horizon of Sgr A*

Solar active regions are distinguished by their strong magnetic fields. Modern local helioseismology seeks to probe them by observing waves which emerge at the solar surface having passed through their interiors. We address the question of how an acoustic wave from below is partially converted to magnetic waves as it passes through a vertical magnetic field layer where the sound and Alfvén speeds coincide (the equipartition level), and find that (i) there is no associated reflection at this depth, either acoustic or magnetic, only transmission and conversion to an ongoing magnetic wave; and (ii) conversion in active regions is likely to be strong, though not total, at frequencies typically used in local helioseismology, with lower frequencies less strongly converted. A simple analytical formula is presented for the acoustic-to-magnetic conversion coefficient.     

Seismic tomography of the near solar surface

Surface gravity waves have been used to probe flows in the two megameters beneath the photosphere using the techniques of timedistance helioseismology. The results suggest that supergranule velocities are smaller than at the surface. The outward flow outside a sunspot penumbra (the moat) is observed, as is an inward flow in the region beyond the moat.     

The effects of Martian near surface conditions on the photochemistry of amino acids

In order to understand the complex multi-parameter system of destruction of organic material on the surface of Mars, step-by-step laboratory simulations of processes occurring on the surface of Mars are necessary. This paper describes the measured effects of two parameters, a CO₂ atmosphere and low temperature, on the destruction rate of amino acids when irradiated with Mars-like ultraviolet light (UV). The results show that the presence of a 7 mbar CO₂ atmosphere does not affect the destruction rate of glycine, and that cooling the sample to 210 K (average Mars temperature) lowers the destruction rate by a factor of 7. The decrease in the destruction rate of glycine by cooling the sample is thought to be predominantly caused by the slower reaction kinetics. When these results are scaled to Martian lighting conditions, cold thin films of glycine are assumed to have half-lives of 250 h under noontime peak illumination. It has been hypothesised that the absence of detectable native organic material in the Martian regolith points to the presence of oxidising agents. Some of these agents might form via the interaction of UV with compounds in the atmosphere. Water, although a trace component of Mars’ atmosphere, is suggested to be a significant source of oxidising species. However, gaseous CO₂ or adsorbed H₂O layers do not influence the photodestruction of amino acids significantly in the absence of reactive soil. Other mechanisms such as chemical processes in the Martian regolith need to be effective for rapid organic destruction.     

Imaging optically-thin hotspots near the black hole horizon of Sgr A* at radio and near-infrared wavelengths

Submilliarcsecond astrometry and imaging of the black hole Sgr A* at the Galactic Centre may become possible in the near future at infrared and submillimetre wavelengths. Motivated by the observations of short-term infrared and X-ray variability of Sgr A*, in a previous paper, we computed the expected images and light curves, including polarization, associated with a compact emission region orbiting the central black hole. We extend this work, using a more realistic hotspot model and including the effects of opacity in the underlying accretion flow. We find that at infrared wavelengths, the qualitative features identified by our earlier work are present, namely it is possible to extract the black hole mass and spin from spot images and light curves of the observed flux and polarization. At radio wavelengths, disc opacity produces significant departures from the infrared behaviour, but there are still generic signatures of the black hole properties. Detailed comparison of these results with future data can be used to test general relativity and to improve existing models for the accretion flow in the immediate vicinity of the black hole.     

Mean surface brightness as a criterion for or against the expansion of the Universe

Using the well-known relation for the mean surface brightness, the author gives the concept of the decision regarding the expansion of the Universe. The most serious obstacle on this way was the low precision of parameter measurements which one could achieve in the past. This paper brings the first step for eventual judgement if the Universe expand or not because the accuracy of measurements has advanced. In this sence, we need some more determinations with present accuracy to give the decisive result because the mean surface brightness must faint by 1.46 mag per square arc sec for red shift of 0.4, and this is sufficient to measure and statistically elaborate it.     

Oblique MHD shock near the surface of young stars

The dependence of the spectrum of a hot spot at the surface of accreting young stars on the angle at which the material falls onto the star is considered. For typical parameters of T Tauri stars the structure of the shock at oblique incidence has been found to be no different from its structure at normal incidence, but at the same time the inclination, along with the gas density and velocity, is shown to be an independent accretion parameter the changes in which lead to noticeable changes in the hot-spot spectrum.     

The Global Structure of the Colliding Bubble Braneworld Universe

The one-brane Randall-Sundrum model offers an example of a model with an `infinite' extra dimension in which ordinary gravity is recovered at large distances and the usual (3+1)-dimensional cosmology at late cosmic times. This is possible because the `bulk' has the geometry of anti de Sitter space, the curvature length ℓ of which delineates the (3+1)-dimensional behavior at large distances from the (4+1)-dimensional behavior at short distances. This spacetime, however, possesses a past Cauchy horizon on which initial data must be specified in a natural and convincing way. A more complete story is required that singles out some set of initial conditions to resolve the `bulk' smoothness and horizon problems. One such complete story is offered by the colliding bubble braneworld universe, where bubbles filled with AdS ⁵ nucleate from dS ⁵ or M ⁵ through quantum tunnelling. A pair of such colliding bubbles forms a Randall-Sundrum-like universe in the future of the collision. Because of the symmetry of bubbles produced through quantum tunnelling, the resulting universe is spatially homogeneous and isotropic at leading order, and the perturbations at the next order are completely well defined and calculable. In this contribution we discuss the possible global structure of such a spacetime. This revised version was published online in July 2006 with corrections to the Cover Date.     

The estimation of the mean density in the Universe

The mean density of matter, as estimated from deep optical samples of galaxies, is too low to close the Universe. However, some additional considerations do not exclude such a possibility.     

The clustering of barred galaxies in the local Universe

We study the clustering properties of barred galaxies using data from the Sloan Digital Sky Survey. We compute projected redshift-space two-point cross-correlation functions   w _p( r _p)  for a sample of nearly 1000 galaxies for which we have performed detailed structural decompositions using the methods described in Gadotti. The sample includes 286 barred galaxies. The clustering of barred and unbarred galaxies of similar stellar mass is indistinguishable over all the scales probed (∼20 kpc–30 Mpc). This result also holds even if the sample is restricted to bars with bluer   g − i   colours (and hence younger ages). Our result also does not change if we split our sample of barred galaxies according to bar-to-total luminosity ratio, bar boxyness, effective surface brightness, length or the shape of the surface density profile within the bar. There is a hint that red, elliptical bars are more strongly clustered than red and less elliptical bars, on scales  ≳1 Mpc  , although the statistical significance is not high. We conclude that there is no significant evidence that bars are a product of mergers or interactions. We tentatively interpret the stronger clustering of the more elliptical bars as evidence that they are located in older galaxies, which reside in more massive haloes.     

The limits of bound structures in the accelerating Universe

According to the latest evidence, the Universe is entering an era of exponential expansion, where gravitationally bound structures will get disconnected from each other, forming isolated 'island universes'. In this scenario, we present a theoretical criterion to determine the boundaries of gravitationally bound structures and a physically motivated definition of superclusters as the largest bound structures in the Universe. We use the spherical collapse model self-consistently to obtain an analytical condition for the mean density enclosed by the last bound shell of the structure (2.36 times the critical density in the present Universe, assumed to be flat, with 30 per cent matter and 70 per cent cosmological constant, in agreement with the previous, numerical result of Chiueh & He). N -body simulations extended to the future show that this criterion, applied at the present cosmological epoch, defines a sphere that encloses ≈99.7 per cent of the particles that will remain bound to the structure at least until the scale parameter of the Universe is 100 times its present value. On the other hand, (28 ± 13) per cent of the enclosed particles are in fact not bound, so the enclosed mass overestimates the bound mass, in contrast with the previous, less rigorous criterion of, e.g. Busha and collaborators, which gave a more precise mass estimate. We also verify that the spherical collapse model estimate for the radial infall velocity of a shell enclosing a given mean density gives an accurate prediction for the velocity profile of infalling particles, down to very near the centre of the virialized core.     

The estimation of the mean density in the Universe

The mean density of matter, as estimated from deep optical samples of galaxies, is too low to close the Universe. However, some additional considerations do not exclude such a possibility.     

Inverse compton emission of gamma rays near the pulsar surface

The physical conditions near pulsar surface that might give rise to gamma ray emission from Crab and Vela pulsars are not yet well understood. Here I suggest that, in the context of the vacuum discharge mechanism proposed by Ruderman and Sutherland (1975), gamma rays are produced by inverse Compton scattering of secondary electrons with the thermal radiation of the star surface as well as for curvature and synchrotron radiation. It is found that inverse Compton scattering is relevant if the neutron star surface temperature is greater than 10⁶K or if the polar cap temperature is of the order of 5×10⁶K. Inverse Compton scattering in anisotropic photon fields and Klein-Nishina regime is here carefully considered.     

The role of expansion for the entropy of the Universe

Under assumption of the closed FRW-universe, the idea is presented that the cosmological expansion/contraction on its own, has an entropy balancing effectively the changing entropy of the cosmic fluid in such a way that at every epoch the total entropy of the Universe remains constant.