The recent WMAP and Planck data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Many extensions of the standard model provide dark matter candidates, in particular Weakly I
nteracting Massive Particles (WIMPs). Thus the direct dark matter detection is central to particle physics and cosmology. Most of the research on this issue has hitherto focused on the detection of the recoiling nucleus. In this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. Examples considered previously were the first excited states of $^{127}$I and $^{129}$Xe. We examine here $^{83}$Kr, which offers some kinematical advantages and is currently considered as a possible target. We find appreciable branching ratios for the inelastic scattering mediated by the spin cross sections, with an inelastic event rate of $4.4times 10^{-4}$kg$^{-1}$d$^{-1}$. So, the extra signature of the gamma ray following the de-excitation of these states can, in principle, be exploited experimentally. A brief discussion of the experimental feasibility is given
We present the results of a systematic search for molecular hydrogen (H2) in low redshift ($ 0.05 lesssim z lesssim 0.7$) DLAs and sub-DLAs with $N(HI) gtrsim 10^{19.0}$ cm$^{-2}$, in the archival HST/COS spectra. Our core sample is comprised of 27 s
ystems with a median $log N(HI) = 19.6$. On the average, our survey is sensitive down to $log N(H2) = 14.4$ corresponding to a molecular fraction of $log f_{H2} = -4.9$ at the median $N(HI)$. H2 is detected in 10 cases (3/5 DLAs and 7/22 sub-DLAs) down to this $f_{H2}$ limit. The H2 detection rate of $50^{+25}_{-12}$ percent seen in our sample, is a factor of $gtrsim 2$ higher than that of the high-$z$ sample of Noterdaeme et al. (2008), for systems with $N(H2) > 10^{14.4}$ cm$^{-2}$. In spite of having $N(HI)$ values typically lower by a factor of 10, low-$z$ H2 systems show molecular fractions ($log f_{H2}=-1.93pm0.63$) that are comparable to the high-$z$ sample. The rotational excitation temperatures ($T_{01} = 133pm55$ K), as measured in our low-$z$ sample, are typically consistent with high-$z$ measurements. Simple photoionization models favour a radiation field much weaker than the mean Galactic ISM field for a particle density in the range 10 - 100 cm$^{-3}$. The impact parameters of the identified host-galaxy candidates are in the range $10 lesssim rho$ (kpc) $lesssim 80$. We, therefore, conjecture that the low-$z$ H2 bearing gas is not related to star-forming disks but stems from self-shielded, tidally stripped or ejected disk-material in the extended halo.
We present images of C110$alpha$ and H110$alpha$ radio recombination line (RRL) emission at 4.8 GHz and images of H166$alpha$, C166$alpha$ and X166$alpha$ RRL emission at 1.4 GHz, observed toward the starforming region NGC 2024. The 1.4 GHz image wit
h angular resolution $sim$ 70arcsec is obtained using VLA data. The 4.8 GHz image with angular resolution $sim$ 17arcsec is obtained by combining VLA and GBT data. The similarity of the LSR velocity (10.3 kms) of the C110$alpha$ line to that of lines observed from molecular material located at the far side of the HII region suggests that the photo dissociation region (PDR) responsible for C110$alpha$ line emission is at the far side. The LSR velocity of C166$alpha$ is 8.8 kms. This velocity is comparable with the velocity of molecular absorption lines observed from the foreground gas, suggesting that the PDR is at the near side of the HII region. Non-LTE models for carbon line forming regions are presented. Typical properties of the foreground PDR are $T_{PDR} sim 100$ K, $n_e^{PDR} sim 5$ cmthree, $n_H sim 1.7 times 10^4$ cmthree, path length $l sim 0.06$ pc and those of the far side PDR are $T_{PDR} sim$ 200 K, $n_e^{PDR} sim$ 50 cmthree, $n_H sim 1.7 times 10^5$ cmthree, $l sim$ 0.03 pc. Our modeling indicates that the far side PDR is located within the HII region. We estimate magnetic field strength in the foreground PDR to be 60 $mu$G and that in the far side PDR to be 220 $mu$G. Our field estimates compare well with the values obtained from OH Zeeman observations toward NGC 2024.
We present observations of the extended solar cycle activity in white-light coronagraphs, and compare them with the more familiar features seen in the Fe XIV green-line corona. We show that the coronal activity zones seen in the emission corona can b
e tracked high into the corona. The peak latitude of the activity, which occurs near solar maximum, is found to be very similar at all heights. But we find that the equatorward drift of the activity zones is faster at greater heights, and that during the declining phase of the solar cycle, the lower branch of activity (that associated with the current cycle) disappears at about 3 Ro. This implies that that during the declining phase of the cycle, the solar wind detected near Earth is likely to be dominated by the next cycle. The so-called rush to the poles is also seen in the higher corona. In the higher corona it is found to start at a similar time but at lower latitudes than in the green-line corona. The structure is found to be similar to that of the equatorward drift.
The onset of the Rush to the Poles of polar-crown prominences and their associated coronal emission is a harbinger of solar maximum. Altrock (Solar Phys. 216, 343, 2003) showed that the Rush was well-observed at 1.15 Ro in the Fe XIV corona at the Sa
cramento Peak site of the National Solar Observatory prior to the maxima of Cycles 21 to 23. The data show that solar maximum in those cycles occurred when the center line of the Rush reached a critical latitude of 76 +- 2{deg}. Furthermore, in the previous three cycles solar maximum occurred when the highest number of Fe XIV emission features per day (averaged over 365 days and both hemispheres) first reached latitudes 20 +- 1.7{deg}. Cycle 24 displays an intermittent Rush that is only well-defined in the northern hemisphere. In 2009 an initial slope of 4.6{deg}/yr was found in the north, compared to an average of 9.4 +- 1.7 {deg}/yr in the previous cycles. An early fit to the Rush would have reached 76{deg} at 2014.6. However, in 2010 the slope increased to 7.5{deg}/yr (an increase did not occur in the previous three cycles). Extending that rate to 76 +- 2{deg} indicates that the solar maximum in the northern hemisphere already occurred at 2011.6 +- 0.3. In the southern hemisphere the Rush to the Poles, if it exists, is very poorly defined. A linear fit to several maxima would reach 76{deg} in the south at 2014.2. In 1999, persistent Fe XIV coronal emission known as the extended solar cycle appeared near 70{deg} in the north and began migrating towards the equator at a rate 40% slower than the previous two solar cycles. However, in 2009 and 2010 an acceleration occurred. Currently the greatest number of emission features is at 21{deg} in the North and 24{deg}in the South. This indicates that solar maximum is occurring now in the North but not yet in the South.
The 2011 Nobel Prize in Physics was awarded for the discovery of accelerating supernovae dimness, suggesting a remarkable change in the expansion rate of the Universe from a decrease since the big bang to an increase, driven by anti-gravity forces of
a mysterious dark energy material comprising 70% of the Universe mass-energy. Fluid mechanical considerations falsify both the accelerating expansion and dark energy concepts. Kinematic viscosity is neglected in current standard models of self-gravitational structure formation, which rely on cold dark matter CDM condensations and clusterings that are also falsified by fluid mechanics. Weakly collisional CDM particles do not condense but diffuse away. Photon viscosity predicts superclustervoid fragmentation early in the plasma epoch and protogalaxies at the end. At the plasma-gas transition, the plasma fragments into Earth-mass gas planets in trillion planet clumps (proto-globular-star-cluster PGCs). The hydrogen planets freeze to form the dark matter of galaxies and merge to form their stars. Dark energy is a systematic dimming error for Supernovae Ia caused by dark matter planets near hot white dwarf stars at the Chandrasekhar carbon limit. Evaporated planet atmospheres may or may not scatter light from the events depending on the line of sight.
This paper describes the partial wave expansion and integral representation of Bessel beams in free space and in the presence of dispersion. The expansion of the Bessel beam wavepacket with constant spectrum is obtained as well. Furthermore, the sum
of a triple Legendre polynomial product of same order but different argument follows naturally from the partial wave expansion. The integration of all Bessel beams over all conical angles is shown to have a simple series representation, which confirms the equivalence between the results for both expansion and integral representation.
Discovered over 30 years ago, the B[e] phenomenon has not yet revealed all its puzzles. New objects that exhibit it are being discovered in the Milky Way, and properties of known objects are being constrained. We review recent findings about objects
of this class and their subgroups as well as discuss new results from studies of the objects with yet unknown nature. In the Magellanic Clouds, the population of such objects has been restricted to supergiants. We present new candidates with apparently lower luminosities found in the LMC.
While Kolmogorov complexity is the accepted absolute measure of information content in an individual finite object, a similarly absolute notion is needed for the information distance between two individual objects, for example, two pictures. We give
several natural definitions of a universal information metric, based on length of shortest programs for either ordinary computations or reversible (dissipationless) computations. It turns out that these definitions are equivalent up to an additive logarithmic term. We show that the information distance is a universal cognitive similarity distance. We investigate the maximal correlation of the shortest programs involved, the maximal uncorrelation of programs (a generalization of the Slepian-Wolf theorem of classical information theory), and the density properties of the discrete metric spaces induced by the information distances. A related distance measures the amount of nonreversibility of a computation. Using the physical theory of reversible computation, we give an appropriate (universal, anti-symmetric, and transitive) measure of the thermodynamic work required to transform one object in another object by the most efficient process. Information distance between individual objects is needed in pattern recognition where one wants to express effective notions of pattern similarity or cognitive similarity between individual objects and in thermodynamics of computation where one wants to analyse the energy dissipation of a computation from a particular input to a particular output.
Open and globular star clusters have served as benchmarks for the study of stellar evolution due to their supposed nature as simple stellar populations of the same age and metallicity. After a brief review of some of the pioneering work that establis
hed the importance of imaging stars in these systems, we focus on several recent studies that have challenged our fundamental picture of star clusters. These new studies indicate that star clusters can very well harbour multiple stellar populations, possibly formed through self-enrichment processes from the first-generation stars that evolved through post-main-sequence evolutionary phases. Correctly interpreting stellar evolution in such systems is tied to our understanding of both chemical-enrichment mechanisms, including stellar mass loss along the giant branches, and the dynamical state of the cluster. We illustrate recent imaging, spectroscopic and theoretical studies that have begun to shed new light on the evolutionary processes that occur within star clusters.
