Thompson scattering of cosmic microwave background (CMB) photons off of free electrons during the reionization epoch induces a correlation between the distribution of galaxies and the polarization pattern of the CMB, the magnitude of which is proportional to the quadrupole moment of radiation at the time of scattering. Since the quadrupole moment generated by gravitational waves (GWs) gives rise to a different polarization pattern than that produced by scalar modes, one can put interesting constraints on the strength of GWs on large scales by cross-correlating the small scale galaxy distribution and CMB polarization. We use this method together with Fisher analysis to predict how well future surveys can measure the tensor-to-scalar ratio $r$. We find that with a future CMB experiment with detector noise Delta_P = 2 mu K-arcmin and a beam width theta_FWHM = 2' and a future galaxy survey with limiting magnitude I<25.6 one can measure the tensor-to-scalar ratio with an error sigma_r \simeq 0.09. To measure r \approx 0.01, however, one needs Delta_P \simeq 0.5 mu K-radian and theta_FWHM \simeq 1'. We also investigate a few systematic effects, none of which turn out to add any biases to our estimators, but they increase the error bars by adding to the cosmic variance. The incomplete sky coverage has the most dramatic effect on our constraints on r for large sky cuts, with a reduction in signal-to-noise smaller than one would expect from the naive estimate (S/N)^2 \propto f_sky. Specifically, we find a degradation factor of f_deg=0.32 \pm 0.01 for a sky cut of |b|>10^\circ (f_sky=0.83) and f_deg=0.056 \pm 0.004 for a sky cut of |b|>20^\circ (f_sky=0.66). Nonetheless, given that our method has different systematics than the more conventional method of observing the large scale B modes directly, it may be used as an important check in the case of a detection.

We know very little about primordial curvature perturbations on scales smaller than about a Mpc. Measurements of the mu-type distortion of the CMB spectrum provide the unique opportunity to probe these scales over the unexplored range from 50 to 10^4 Mpc^-1. This is a very clean probe, in that it relies only on well-understood linear evolution. We point out that correlations between mu-distortion and temperature anisotropies can be used to test Gaussianity at these very small scales. In particular the mu-T cross correlation is proportional to the very squeezed limit of the primordial bispectrum and hence measures fNL^loc{\ss}, while mu-mu is proportional to the primordial trispectrum and measures tauNL. We present a Fisher matrix forecast of the observational constraints.

(ABRIDGED) We present tentative evidence for the existence of a dissolved star cluster in the Sextans dwarf spheroidal galaxy. In a sample of six stars, three (possibly four) stars around [Fe/H] = -2.7 are identified as potential cluster stars by the technique of chemical tagging. This finding, together with the recognition of an apparent excess of stars in the metallicity distribution function (MDF) of Sextans at a similar metallicity as the cluster stars, is used to estimate the initial stellar mass of the parent cluster to M_*,init = 1.9^{+1.5}_{-0.9} (1.6^{+1.2}_{-0.8}) x 10^5 M_sol, assuming a Salpeter (Kroupa) initial mass function (IMF). If corroborated by follow-up spectroscopy, this star cluster at [Fe/H] = -2.7 is the most metal-poor system identified to date. In an era of extremely large telescopes, we anticipate that chemical tagging will be a powerful technique, in particular for tracing the star formation process and the evolution of the initial cluster mass function in dwarf galaxies, and for putting firm constraints on the dwarf-galaxy origin of the Milky Way's stellar halo. From available observational data, we also argue that the average star cluster mass in the majority of the newly discovered ultra-faint dwarf galaxies was notably lower than it is in the Galaxy today and possibly lower than in the more luminous, classical dwarf spheroidal galaxies. Moreover, the slope of the cumulative metallicity function (below [Fe/H] = -2.5) in dwarf spheroidals falls below that of the ultra-faints, which increases with increasing metallicity as predicted from our stochastic chemical evolution model. These two findings, together with a possible difference in the <[Mg/Fe]> ratio suggest that the ultra-faint dwarf galaxy population, or a significant fraction thereof, and the dwarf spheroidal population, were formed in different environments and would thus be distinct in origin.

We present GALEX data for 44 Galactic globular clusters obtained during 3 GALEX observing cycles between 2004 and 2008. This is the largest homogeneous data set on the UV photometric properties of Galactic globular clusters ever collected. The sample selection and photometric analysis are discussed, and color-magnitude diagrams are presented. The blue and intermediate-blue horizontal branch is the dominant feature of the UV color-magnitude diagrams of old Galactic globular clusters. Our sample is large enough to display the remarkable variety of horizontal branch shapes found in old stellar populations. Other stellar types that are obviously detected are blue stragglers and post core-He burning stars. The main features of UV color-magnitude diagrams of Galactic globular clusters are briefly discussed. We establish the locus of post-core He burning stars in the UV color-magnitude diagram and present a catalog of candidate AGB-manqu \'e, post early-AGB, and post-AGB stars within our cluster sample.

Incoherent dedispersion is a computationally intensive problem that appears frequently in pulsar and transient astronomy. For current and future transient pipelines, dedispersion can dominate the total execution time, meaning its computational speed acts as a constraint on the quality and quantity of science results. It is thus critical that the algorithm be able to take advantage of trends in commodity computing hardware. With this goal in mind, we present analysis of the 'direct', 'tree' and 'sub-band' dedispersion algorithms with respect to their potential for efficient execution on modern graphics processing units (GPUs). We find all three to be excellent candidates, and proceed to describe implementations in C for CUDA using insight gained from the analysis. Using recent CPU and GPU hardware, the transition to the GPU provides a speed-up of 9x for the direct algorithm when compared to an optimised quad-core CPU code. For realistic recent survey parameters, these speeds are high enough that further optimisation is unnecessary to achieve real-time processing. Where further speed-ups are desirable, we find that the tree and sub-band algorithms are able to provide 3-7x better performance at the cost of certain smearing, memory consumption and development time trade-offs. We finish with a discussion of the implications of these results for future transient surveys. Our GPU dedispersion code is publicly available as a C library at: this http URL

We report on the discovery of an instability in low mass stars just above the threshold ($\sim 0.35 \textrm{M}_{\odot}$) where they are expected to be fully convective on the main sequence. Non-equilibrium He3 burning creates a convective core, which is separated from a deep convective envelope by a small radiative zone. The steady increase in central He3 causes the core to grow until it touches the surface convection zone, which triggers fully convective episodes in what we call the "convective kissing instability". These episodes lower the central abundance and cause the star to return to a state in which is has a separate convective core and envelope. These periodic events eventually cease when the He3 abundance throughout the star is sufficiently high that the star is fully convective, and remains so for the rest of its main sequence lifetime. The episodes correspond to few percent changes in radius and luminosity, over Myr to Gyr timescales. We discuss the physics of the instability, as well as prospects for detecting its signatures in open clusters and wide binaries. Secondary stars in cataclysmic variables (CVs) will pass through this mass range, and this instability could be related to the observed paucity of such systems for periods between two and three hours. We demonstrate that the instability can be generated for CV secondaries with mass-loss rates of interest for such systems, and discuss potential implications.

Using a new large-scale (~ 0.75 Gpc)^3 hydrodynamic cosmological simulation we investigate the growth rate of supermassive black holes in the early universe (z > 4.75). Remarkably, we find a clear peak in the typical Eddington ratio at black hole masses of 4-8 * 10^7 solar masses (typically found in halos of ~7 * 10^11 to 10^12 solar masses), independent of redshift and indicative that most of BH growth occurs in the cold-flow dominated regime. Black hole growth is by and large regulated by the evolution of gas density. The typical Eddington ratio at a given mass scales simply as cosmological density (1+z)^3 and the peak is caused by the competition between increased gas density available in more massive hosts, and a decrease due to strong AGN feedback that deprives the black hole of sufficient gas to fuel further rapid growth in the high mass end. In addition to evolution in the mean Eddington ratio, we show that the distribution of Eddington ratio among both mass-selected and luminosity-selected samples is approximately log-normal. We combine these findings into a single log-normal fitting formula for the distribution of Eddington ratios as a function of (M_BH,z). This formula can be used in analytic and semi analytic models for evolving black hole populations, predicting black hole masses of observed quasars, and, in conjunction with the observed distribution of Eddington ratios, can be used to constrain the black hole mass function.

We estimate the total dust input from the cool evolved stars in the Small Magellanic Cloud (SMC), using the 8 micron excess emission as a proxy for the dust-production rate. We find that Asymptotic Giant Branch (AGB) and red supergiant (RSG) stars produce (8.6-9.5) x 10^7 solar masses per year of dust, depending on the fraction of far-infrared sources that belong to the evolved star population (with 10%-50% uncertainty in individual dust-production rates). RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called "extreme" AGB stars) account for 87%-89% of the total dust input from cool evolved stars. We also estimate the dust input from hot stars and supernovae (SNe), and find that if SNe produce 10^-3 solar masses of dust each, then the total SN dust input and AGB input are roughly equivalent. We consider several scenarios of SNe dust production and destruction and find that the interstellar medium (ISM) dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. We find that AGB stars contribute only 2.1% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggests that dust must grow in the ISM or be formed by another unknown mechanism.

We study the effects of feebly or non-annihilating weakly interacting Dark Matter (DM) particles on stars that live in DM environments denser than that of our Sun. We find that the energy transport mechanism induced by DM particles can produce unusual conditions in the core of Main Sequence stars, with effects which can potentially be used to probe DM properties. We find that solar mass stars placed in DM densities of rhochi>= e2 GeV/cm3 are sensitive to Spin-Dependent scattering cross-section sigmsd >= e-37 cm2 and a DM particle mass as low as mchi=5 GeV, accessing a parameter range weakly constrained by current direct detection experiments.

Conversion of photons into axions under the presence of a strong magnetic field can dim the radiation from magnetized astrophysical objects. Here we perform a detailed calculation aimed at quantifying the signatures of photon-axion conversion in the spectra, light curves, and polarization of neutron stars (NSs). We take into account the energy and angle-dependence of the conversion probability and the surface thermal emission from NSs. The latter is computed from magnetized atmosphere models that include the effect of photon polarization mode conversion due to vacuum polarization. The resulting spectral models, inclusive of the general-relativistic effects of gravitational redshift and light deflection, allow us to make realistic predictions for the effects of photon to axion conversion on observed NS spectra, light curves, and polarization signals. We identify unique signatures of the conversion, such as an increase of the effective area of a hot spot as it rotates away from the observer line of sight. For a star emitting from the entire surface, the conversion produces apparent radii that are either larger or smaller (depending on axion mass and coupling strength) than the limits set by NS equations of state. For an emission region that is observed phase-on, photon-axion conversion results in an inversion of the plane of polarization with respect to the no-conversion case. While the quantitative details of the features that we identify depend on NS properties (magnetic field strength, temperature) and axion parameters, the spectral and polarization signatures induced by photon-axion conversion are distinctive enough to make NSs very interesting and promising probes of axion physics.

Hot Jupiters, due to the proximity to their parent stars, are subjected to a strong irradiating flux which governs their radiative and dynamical properties. We compute a suite of 3D circulation models with dual-band radiative transfer, exploring a relevant range of irradiation temperatures (770K <~ Tirr <~ 3000K), both with and without temperature inversions. We find that, for irradiation temperatures Tirr <~ 2000K, heat redistribution is very efficient, producing comparable day- and night-side fluxes. For Tirr ~ 2200-2400K, redistribution starts to break down, resulting in a high day-night flux contrast. Our simulations support the physical intuition that the efficiency of heat transfer is primarily governed by the ratio of advective to radiative timescales. For the same Tirr, models with temperature inversions display a higher day-night contrast, but we find this opacity-driven effect to be secondary to irradiation. The hotspot offset from the substellar point is large when insolation is weak and redistribution is efficient, and decreases as redistribution breaks down. We further explore the importance of various dissipation mechanisms with the strength of the irradiating flux. The atmospheric flow can be potentially subjected to the Kelvin-Helmholtz instability only in the uppermost layers, with a depth that penetrates to pressures of a few millibars at most. Shocks penetrate deeper, down to several bars in the hottest model. For a B ~ a few Gauss, Ohmic dissipation generally occurs down to deeper levels than shock dissipation (to tens of bars), but the penetration depth varies with the atmospheric opacity. The total dissipated Ohmic power increases steeply with the strength of the irradiating flux and the dissipation depth recedes into the atmosphere, favoring radius inflation in the most irradiated objects. (Abridged)

We study SN 2006oz, a newly-recognized member of the class of H-poor, super-luminous supernovae. We present multi-color light curves from the SDSS-II SN Survey, covering the rise time, as well as an optical spectrum showing that the explosion occurred at z~0.376. We fit black body functions to estimate the temperature and radius evolution of the photosphere and use the parametrized code SYNOW to model the spectrum. We construct a bolometric light curve and compare with explosion models. The very early light curves show a dip in the g and r-bands and a possible initial cooling phase in the u-band before rising to maximum light. The bolometric light curve shows a precursor plateau with a duration between 6-10 days in the rest-frame. A lower limit of M_u < -21.5 can be placed on the absolute peak luminosity of the SN, while the rise time is constrained to be at least 29 days. During our observations, the emitting sphere doubled its radius to 2x10^15 cm, while the temperature remained hot at 15000 K. As for other similar SNe, the spectrum is best modeled with elements including O II and Mg II, while we tentatively suggest that Fe III might be present. We suggest that the precursor plateau might be related to a recombination wave in a circumstellar medium (CSM) and discuss whether it is a common property of all similar explosions. The subsequent rise can be equally well described by input from a magnetar or by ejecta-CSM interaction, but the models are not well constrained due to the lack of post-maximum observations, and CSM interaction has difficulties accounting for the precursor plateau self-consistently. Radioactive decay is less likely as a mechanism powering the luminosity. The host galaxy, detected in deep imaging with the 10 m GTC, is a moderately young and star-forming, but not a starburst, galaxy. It has an absolute magnitude of M_g = -16.9.

We present a 100 ks Chandra observation studying the extended X-ray emission around the powerful z=1.04 quasar PKS1229-021. The diffuse cluster X-ray emission can be traced out to ~15 arcsec (~120 kpc) radius and there is a drop in the calculated hardness ratio inside the central 5 arcsec consistent with the presence of a cool core. Radio observations of the quasar show a strong core and a bright, one-sided jet leading to the SW hot spot and a second hot spot visible on the counter-jet side. Although the wings of the quasar PSF provided a significant contribution to the total X-ray flux at all radii where the extended cluster emission was detected, we were able to accurately subtract off the PSF emission using ChaRT and marx simulations. The resulting steep cluster surface brightness profile for PKS1229-021 appears similar to the profile for the FRII radio galaxy 3C444, which has a similarly rapid surface brightness drop caused by a powerful shock surrounding the radio lobes (Croston et al.). Using a model surface brightness profile based on 3C444, we estimated the total cluster luminosity for PKS1229-021 to be L_X ~ 2 x 10^{44} erg/s. We discuss the difficulty of detecting cool core clusters, which host bright X-ray sources, in high redshift surveys.

In the past few years more and more pieces of evidence have been presented for a revision of the widely accepted Unified Model of Active Galactic Nuclei. A model based solely on orientation cannot explain all the observed phenomenology. In the following, we will present evidence that accretion rate is also a key parameter for the presence of Hidden Broad Line Regions in Seyfert 2 galaxies. Our sample consists of 21 sources with polarized Hidden Broad Lines and 18 sources without Hidden Broad Lines. We use stellar velocity dispersions from several studies on the CaII and Mg b triplets in Seyfert 2 galaxies, to estimate the mass of the central black holes via the Mbh-{\sigma}\ast relation. The ratio between the bolometric luminosity, derived from the intrinsic (i.e. unabsorbed) X-ray luminosity, and the Eddington luminosity is a measure of the rate at which matter accretes onto the central supermassive black hole. A separation between Compton-thin HBLR and non-HBLR sources is clear, both in accretion rate (log Lbol/LEdd = -1.9) and in luminosity (log Lbol = 43.90). When, properly luminosity-corrected, Compton-thick sources are included, the separation between HBLR and non-HBLR is less sharp but no HBLR source falls below the Eddington ratio threshold. We speculate that non-HBLR Compton-thick sources with accretion rate higher than the threshold, do possess a BLR, but something, probably related to their heavy absorption, is preventing us from observing it even in polarized light. Our results for Compton-thin sources support theoretical expectations. In a model presented by Nicastro (2000), the presence of broad emission lines is intrinsically connected with disk instabilities occuring in proximity of a transition radius, which is a function of the accretion rate, becoming smaller than the innermost stable orbit for very low accretion rates and therefore luminosities.

The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first 0.5-4 days. In addition, the composite lightcurves formed from stacking together many Type Ia supernovae (SNe Ia) show a similar power-law index of 1.8+-0.2 with time. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that the rise of SN 2011fe requires a mass fraction 0.03 of 56Ni (or some other heating source like 48Cr) distributed between a depth of ~0.004-0.1Msun below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the event, so comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the distribution of shallow radioactive material, providing important clues for identifying the elusive progenitors of SNe Ia.

We present a revised analysis of a speculated stellar bridge between the Milky Way dwarf galaxies Leo IV and Leo V. Using data acquired with Subaru/Suprime-Cam over a 1deg x 4deg field encompassing the two satellites and the region in between, we confirm our previous detection of a stellar overdensity between Leo IV and Leo V (de Jong et al. 2010). The larger area coverage and improved depth of our current dataset allow for an improved analysis of the stellar overdensity that had previously appeared to bridge the two galaxies. A main-sequence turn-off feature visible in the stacked colour-magnitude diagram of the contiguously observed Subaru fields reveals an extended stellar structure at a distance of approximately 20 kpc. Its angular proximity to the Virgo overdensity, as well as a good correspondence in distance and metallicity, suggests that the smaller structure we detect may be associated with the much larger Virgo stellar overdensity.

Multi-wavelength light curves of bright gamma-ray blazars (e.g., 3C 454.3) reveal strong correlations across wavebands, yet striking dissimilarities in the details. This conundrum can be explained if the variable flux and polarization result from both (1) modulation in the magnetic field and relativistic electron content imparted at the jet input and (2) turbulence in the flow. In the Turbulent Extreme Multi-Zone (TEMZ) model being developed by the author, much of the optical and high-energy radiation in a blazar is emitted near the 43 GHz core of the jet as seen in VLBA images, parsecs from the central engine, as indicated by observations of a number of blazars. The model creates simulated light curves through numerical calculations that approximate the behavior of turbulent plasma - modulated by random fluctuations of the jet flow - crossing a cone-shaped standing shock system that compresses the plasma and accelerates electrons to highly relativistic energies. A standing shock oriented transverse to the jet axis (Mach disk) at the vertex of the conical shock can create a variable nonthermal seed photon field that is highly blueshifted in the frame of the faster jet plasma, leading to highly luminous, rapidly variable gamma-ray emission.

Direct and unequivocal detection of gravitational waves represents a great challenge of contemporary physics and astrophysics. A worldwide effort is currently operating towards this direction, building ever sensitive detectors, improving the modelling of gravitational wave sources and employing ever more sophisticated and powerful data analysis techniques. In this paper we review the current status of LIGO and Virgo ground based interferometric detectors and some data analysis tools used in the continuous wave searches to extract the faint gravitational signals from the interferometric noise data. Moreover we discuss also relevant results from recent continuous wave searches.

We present a new method for confirming transiting planets based on the combination of transit timingn variations (TTVs) and dynamical stability. Correlated TTVs provide evidence that the pair of bodies are in the same physical system. Orbital stability provides upper limits for the masses of the transiting companions that are in the planetary regime. This paper describes a non-parametric technique for quantifying the statistical significance of TTVs based on the correlation of two TTV data sets. We apply this method to an analysis of the transit timing variations of two stars with multiple transiting planet candidates identified by Kepler. We confirm four transiting planets in two multiple planet systems based on their TTVs and the constraints imposed by dynamical stability. An additional three candidates in these same systems are not confirmed as planets, but are likely to be validated as real planets once further observations and analyses are possible. If all were confirmed, these systems would be near 4:6:9 and 2:4:6:9 period commensurabilities. Our results demonstrate that TTVs provide a powerful tool for confirming transiting planets, including low-mass planets and planets around faint stars for which Doppler follow-up is not practical with existing facilities. Continued Kepler observations will dramatically improve the constraints on the planet masses and orbits and provide sensitivity for detecting additional non-transiting planets. If Kepler observations were extended to eight years, then a similar analysis could likely confirm systems with multiple closely spaced, small transiting planets in or near the habitable zone of solar-type stars.

We present a method to confirm the planetary nature of objects in systems with multiple transiting exoplanet candidates. This method involves a Fourier-Domain analysis of the deviations in the transit times from a constant period that result from dynamical interactions within the system. The combination of observed anti-correlations in the transit times and mass constraints from dynamical stability allow us to claim the discovery of four planetary systems Kepler-25, Kepler-26, Kepler-27, and Kepler-28, containing eight planets and one additional planet candidate.

This memo describes the system used to conduct commensal correlator and beamformer observations at the Allen Telescope Array (ATA). This system was deployed for ~2 years until the ATA hibernation in 2011 and was responsible for collecting >5 TB of data during thousands of hours of observations. The general system design is presented and the implementation is discussed in detail. I emphasize the rationale for various design decisions and attempt to document a few aspects of ATA operations that might not be obvious to non-insiders. I close with some recommendations from my experience developing the software infrastructure and managing the correlator observations. These include: reuse existing systems; solve, don't avoid, tensions between projects, and share infrastructure; plan to make standalone observations to complement the commensal ones; and be considerate of observatory staff when deploying new and unusual observing modes. The structure of the software codebase is documented.

Eighty planetary systems of two or more planets are known to orbit stars other than the Sun. For most, the data can be sufficiently explained by non-interacting Keplerian orbits, so the dynamical interactions of these systems have not been observed. Here we present 4 sets of lightcurves from the Kepler spacecraft, which each show multiple planets transiting the same star. Departure of the timing of these transits from strict periodicity indicates the planets are perturbing each other: the observed timing variations match the forcing frequency of the other planet. This confirms that these objects are in the same system. Next we limit their masses to the planetary regime by requiring the system remain stable for astronomical timescales. Finally, we report dynamical fits to the transit times, yielding possible values for the planets' masses and eccentricities. As the timespan of timing data increases, dynamical fits may allow detailed constraints on the systems' architectures, even in cases for which high-precision Doppler follow-up is impractical.

We present a statistical analysis that demonstrates that the overwhelming majority of Kepler candidate multiple transiting systems (multis) indeed represent true, physically-associated transiting planets. Binary stars provide the primary source of false positives among Kepler planet candidates, implying that false positives should be nearly randomly-distributed among Kepler targets. In contrast, true transiting planets would appear clustered around a smaller number of Kepler targets if detectable planets tend to come in systems and/or if the orbital planes of planets encircling the same star are correlated. There are more than one hundred times as many Kepler planet candidates in multi-candidate systems as would be predicted from a random distribution of candidates, implying that the vast majority are true planets. Most of these multis are multiple planet systems orbiting the Kepler target star, but there are likely cases where (a) the planetary system orbits a fainter star, and the planets are thus significantly larger than has been estimated, or (b) the planets orbit different stars within a binary/multiple star system. We use the low overall false positive rate among Kepler multis, together with analysis of Kepler spacecraft and ground-based data, to validate the closely-packed Kepler-33 planetary system, which orbits a star that has evolved somewhat off of the main sequence. Kepler-33 hosts five transiting planets with periods ranging from 5.67 to 41 days.

The radiation from the central regions of active galactic nuclei, including that from the accretion disk surrounding the black hole, is likely to peak in the extreme ultraviolet $\sim 13 -100 \ev$. However, due to Galactic absorption, we are limited to constraining the physical properties - black hole mass and accretion rate - from what observations we have below $\sim 10 \ev$ or above $\sim 100 \ev$. In this paper we predict the thermal and ionization states of warm absorbers as a function of the shape of the unobservable continuum. In particular we model an accretion disk at $kT_{in} \sim 10 \ev$ and a {\it soft excess} at $kT_{se} \sim 150 \ev$. The warm absorber, which is the highly ionized gas along the line of sight to the continuum, shows signatures in the $\sim 0.3 - 2 \kev$ energy range consisting of numerous absorption lines and edges of various ions, some of the prominent ones being H- and He-like oxygen, neon, magnesium and silicon. We find that the properties of the warm absorber are significantly influenced by the changes in the temperature of the accretion disk, as well as by the strength of the {\it soft excess}, as they affect the optical depth particularly for iron and oxygen. These trends may help develop a method of characterising the shape of the unobservable continuum and the occurrence of warm absorbers.

Recent observations of Sgr A$^*$ by Fermi and HESS have detected steady gamma-ray emission in the GeV and TeV bands. We present a new model to explain the GeV gamma-ray emission by inverse Compton scattering by nonthermal electrons supplied by the NIR/X-ray flares of Sgr A$^*$. The escaping electrons from the flare regions accumulate in a region with a size of $\sim 10^{18}$ cm and magnetic fields of $\lesssim 10^{-4}$ G. Those electrons produce gamma-rays by inverse Compton scattering off soft photons emitted by stars and dust around the central black hole. By fitting the GeV spectrum, we find constraints on the magnetic field and the energy density of optical-UV radiation in the central 1 pc region around the supermassive black hole. While the GeV spectrum is well fitted by our model, the TeV $\gamma$-rays, whose spectral index is different from that of the GeV emission, may be from different sources such as pulsar wind nebulae.

We use 3D radiative MHD simulations to investigate the formation and dynamics of small-scale (less than 0.5 Mm in diameter) vortex tubes spontaneously generated by turbulent convection in quiet-Sun regions with initially weak mean magnetic fields. The results show that the vortex tubes penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere. The vortex tubes are mostly concentrated in intergranular lanes and are characterized by strong (near sonic) downflows and swirling motions that capture and twist magnetic field lines, forming magnetic flux tubes that expand with height and which attain magnetic field strengths ranging from 200 G in the chromosphere to more than 1 kG in the photosphere. We investigate in detail the physical properties of these vortex tubes, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that magnetized vortex tubes provide an important path for energy and momentum transfer from the convection zone into the chromosphere.

Aims. The HIFI instrument onboard Herschel has allowed high spectral resolution and sensitive observations of ground-state transi- tions of three molecular ions: the methylidyne cation CH+, its isotopologue 13CH+, and sulfanylium SH+. Because of their unique chemical properties, a comparative analysis of these cations provides essential clues to the link between the chemistry and dynamics of the diffuse interstellar medium. Methods. The CH+, 13CH+, and SH+ lines are observed in absorption towards the distant high-mass star-forming regions (SFRs) DR21(OH), G34.3+0.1, W31C, W33A, W49N, and W51, and towards two sources close to the Galactic centre, SgrB2(N) and SgrA*+50. All sight lines sample the diffuse interstellar matter along pathlengths of several kiloparsecs across the Galactic Plane. In order to compare the velocity structure of each species, the observed line profiles were deconvolved from the hyperfine structure of the SH+ transition and the CH+, 13CH+, and SH+ spectra were independently decomposed into Gaussian velocity components. To analyse the chemical composition of the foreground gas, all spectra were divided, in a second step, into velocity intervals over which the CH+, 13CH+, and SH+ column densities and abundances were derived. Results. SH+ is detected along all observed lines of sight, with a velocity structure close to that of CH+ and 13CH+. The linewidth distributions of the CH+, SH+, and 13CH+ Gaussian components are found to be similar. These distributions have the same mean (<\delta\u{psion}> ~ 4.2 km s-1) and standard deviation (\sigma(\delta\u{psion}) ~ 1.5 km s-1). This mean value is also close to that of the linewidth distribution of the CH+ visible transitions detected in the solar neighbourhood. We show that the lack of absorption components narrower than 2 km s-1 is not an artefact caused by noise: the CH+, 13CH+, and SH+ line profiles are therefore statistically broader than those of most species detected in absorption in diffuse interstellar gas (e. g. HCO+, CH, or CN). The SH+/CH+ column density ratio observed in the components located away from the Galactic centre spans two orders of magnitude and correlates with the CH+ abundance. Conversely, the ratio observed in the components close to the Galactic centre varies over less than one order of magnitude with no apparent correlation with the CH+ abundance. The observed dynamical and chemical properties of SH+ and CH+ are proposed to trace the ubiquitous process of turbulent dissipation, in shocks or shears, in the diffuse ISM and the specific environment of the Galactic centre regions.

We review the particle physics ingredients affecting the normalization, shape, and flavor composition of astrophysical neutrinos fluxes, such as different production modes, magnetic field effects on the secondaries (muons, pions, kaons), and flavor mixing, where we focus on p-gamma interactions. We also discuss the interplay with neutrino propagation and detection, including the possibility to detect flavor and its application in particle physics, and the use of the Glashow resonance to discriminate p-gamma from p-p interactions in the source. We illustrate the implications on fluxes and flavor composition with two different models: 1) the target photon spectrum is dominated by synchrotron emission of co-accelerated electrons and 2) the target photon spectrum follows the observed photon spectrum of gamma-ray bursts. In the latter case, the multi-messenger extrapolation from the gamma-ray fluence to the expected neutrino flux is highlighted.

The two parts of the Konkoly Blazhko Survey (KBS I and II) are introduced. The most important preliminary findings of the second part are presented in comparison to the results of the first part. Two interesting cases of very strong modulation from the KBS II are also shown.

Use of the Hirsch-index ($H$) as measure of an author's visibility in the scientific literature has become popular as an alternative to a gross measure like total citations (c). I show that, at least in astrophysics, $H$ correlates tightly with overall citations. The mean relation is $H=0.5(\sqrt c+1)$. Outliers are few and not too far from the mean, especially if `normalized' ADS citations are used for $c$ and $H$. Whatever the theoretical reasoning behind it, the Hirsch index in practice does not appear to measure something significantly new.

We explore effects of the Shakura-Sunyaev alpha-viscosity on the dynamics and oscillations of slender tori. We start with a slow secular evolution of the torus. We show that the angular-momentum profile approaches the Keplerian one on the timescale longer than a dynamical one by a factor of the order of 1/\alpha. Then we focus our attention on the oscillations of the torus. We discuss effects of various angular momentum distributions. Using a perturbation theory, we have found a rather general result that the high-order acoustic modes are damped by the viscosity, while the high-order inertial modes are enhanced. We calculate a viscous growth rates for the lowest-order modes and show that already lowest-order inertial mode is unstable for less steep angular momentum profiles or very close to the central gravitating object.

The heating of the solar corona is one of the big questions in astrophysics. Rapid pulses called nanoflares are among the best candidate mechanisms. The analysis of the time variability of coronal X-ray emission is potentially a very useful tool to detect impulsive events. We analyze the small-scale variability of a solar active region in a high cadence Hinode/XRT observation. The dataset allows us to detect very small deviations of emission fluctuations from the distribution expected for a constant rate. We discuss the deviations in the light of the pulsed-heating scenario.

The Gould Belt Legacy Survey will map star-forming regions within 500 pc, using HARP (Heterodyne Array Receiver Programme), SCUBA-2 (Submillimetre Common-User Bolometer Array 2) and POL-2 (Polarimeter 2) on the James Clerk Maxwell Telescope (JCMT). This paper describes HARP observations of the J = 3-2 transitions of 13CO and C18O towards Orion A. The 1500-resolution observations cover 5 pc of the Orion filament, including OMC1 (inc. BN-KL and Orion Bar), OMC 2/3 and OMC 4, and allow a comparative study of the molecular gas properties throughout the star-forming cloud. The filament shows a velocity gradient of ~1 km/s /pc between OMC 1, 2 and 3, and high velocity emission is detected in both isotopologues. The Orion Nebula and Bar have the largest masses and line widths, and dominate the mass and energetics of the high velocity material. Compact, spatially resolved emission from CH3CN, 13CH3OH, SO, HCOOCH3, C2H5OH, CH3CHO and CH3OCHO is detected towards the Orion Hot Core. The cloud is warm, with a median excitation temperature of ~24 K; the Orion Bar has the highest excitation temperature gas, at >80 K. The C18O excitation temperature correlates well with the dust temperature (to within 40%). The C18O emission is optically thin, and the 13CO emission is marginally optically thick; despite its high mass, OMC 1 shows the lowest opacities. A virial analysis indicates that Orion A is too massive for thermal or turbulent support, but is consistent with a model of a filamentary cloud that is threaded by helical magnetic fields. The variation of physical conditions across the cloud is reflected in the physical characteristics of the dust cores....continued

We present recent developments in Kinetic Inductance Detectors (KID) for large arrays of detectors. The main application is ground-based millimeter wave astronomy. We focus in particular, as a case study, on our own experiment: NIKA (N\'eel IRAM KID Arrays). NIKA is today the best in-the-field experiment using KID-based instruments, and consists of a dual-band imaging system designed for the IRAM 30 meter telescope at Pico Veleta. We describe in this article, after a general context introduction, the KID working principle and the readout electronics, crucial to take advantage of the intrinsic KID multiplexability. We conclude with a small subset of the astronomical sources observed simultaneously at 2 mm and 1.4 mm by NIKA during the last run, held in October 2010.
Nous d\'ecrivons les r\'ecents d\'eveloppements concernant les grandes matrices de d\'etecteurs \`a inductance cin\'etique (KID) dont l'application principale est l'astronomie millim\'etrique au sol. Nous d\'etaillons en particulier notre propre cam\'era : NIKA (N\'eel IRAM KID Arrays) qui est aujourd'hui l'instrument le plus abouti mettant en oeuvre des KIDs. NIKA est une cam\'era bi-bande con\c{c}ue pour le radiot\'elescope de 30 m\`etres de l'IRAM \`a Pico Veleta. Apr\'es avoir d\'ecrit le contexte instrumental dans lequel ils s'inscrivent, nous expliquerons le principe de fonctionnement des KIDs et de leur \'electronique de lecture, cruciale pour pouvoir tirer parti de leur potentiel de muliplexage. Pour finir, nous pr\'esentons quelques exemples d'observations effectu\'ees par NIKA dans les bandes de 2 mm et 1,4 mm au cours de la derni\`ere campagne d'observation en octobre 2010.

We present a new catalogue of 55,121 groups and clusters centred on Luminous Red Galaxies from SDSS DR7 in the redshift range 0.15<z<0.4. We provide halo mass estimates for each of these groups derived from a calibration between the optical richness of bright galaxies (M_r<-20.5) within 1 Mpc, and X-ray-derived mass for a small subset of 129 groups and clusters with X-ray measurements. We derive the mean (stacked) surface number density profiles of galaxies as a function of total halo mass in different mass bins. We find that derived profiles can be well-described by a projected NFW profile with a concentration parameter (<c>~2.6) that is approximately a factor of two lower than that of the dark matter (as predicted by N-body cosmological simulations) and nearly independent of halo mass. Interestingly, in spite of the difference in shape between the galaxy and dark matter radial distributions, both exhibit a high degree of self-similarity. A self-consistent comparison to several recent semi-analytic models of galaxy formation indicates that: (1) beyond ~0.3 r_500 current models are able to reproduce both the shape and normalisation of the satellite profiles; and (2) within ~0.3 r_500 the predicted profiles are sensitive to the details of the satellite-BCG merger timescale calculation. The former is a direct result of the models being tuned to match the global galaxy luminosity function combined with the assumption that the satellite galaxies do not suffer significant tidal stripping, even though their surrounding dark matter haloes can be removed through this process. Combining our results with measurements of the intracluster light should provide a way to inform theoretical models on the efficacy of the tidal stripping and merging processes.

The first major star-forming galaxies and Active Galactic Nuclei will produce Balmer and higher order extended haloes during the Epoch of Reionization through the scattering of Lyman resonance line photons off the surrounding neutral intergalactic gas. The optical depth dependence of the scattering rates will produce a signal sensitive to both the density and velocity fluctuations of the gas, offering the possibility of probing the ionization region and flow field surrounding young star-forming galaxies. The requirements for detecting the haloes in the infra-red using a space-based telescope are discussed, along with an assessment of the possibility of detecting the haloes using the Tunable Filter Imager on the James Webb Space Telescope.

We have obtained the first estimates of the masses of the components of the Her X-1/HZ Her X-ray binary system taking into account non-LTE effects in the formation of the H_gamma absorption line: mx=1.8Msun and mv=2.5Msun. These mass estimates were made in a Roche model based on the observed radial-velocity curve of the optical star, HZ Her. The masses for the X-ray pulsar and optical star obtained for an LTE model lie are mx=0.85\pm0.15Msun and mv=1.87\pm0.13Msun. These mass estimates for the components of Her X-1/HZ Her derived from the radial-velocity curve should be considered tentative. Further mass estimates from high-precision observations of the orbital variability of the absorption profiles in a non-LTE model for the atmosphere of the optical component should be made.

All the neutron star (NS) atmosphere models published so far have been calculated in the "cold plasma approximation", which neglects the relativistic effects in the radiative processes, such as cyclotron emission/absorption at harmonics of cyclotron frequency. Here we present new NS atmosphere models which include such effects. We calculate a set of models for effective temperatures T_eff =1-3 MK and magnetic fields B \sim 10^{10}-10^{11} G, typical for the so-called central compact objects (CCOs) in supernova remnants, for which the electron cyclotron energy E_{c,e} and its first harmonics are in the observable soft X-ray range. Although the relativistic parameters, such as kT_eff /(m_e c^2) and E_{c,e} /(m_e c^2), are very small for CCOs, the relativistic effects substantially change the emergent spectra at the cyclotron resonances, E \approx sE_{c,e} (s=1, 2,...). Although the cyclotron absorption features can form in a cold plasma due to the quantum oscillations of the free-free opacity, the shape and depth of these features change substantially if the relativistic effects are included. In particular, the features acquire deep Doppler cores, in which the angular distribution of the emergent intensity is quite different from that in the cold plasma approximation. The relative contributions of the Doppler cores to the equivalent widths of the features grow with increasing the quantization parameter b_eff = E_{c,e}/kT_eff and harmonic number s. The total equivalent widths of the features can reach \sim 150-250 eV; they increase with growing b_eff and are smaller for higher harmonics.

The magnetar 1E 1547.0-5408 exhibited outbursts in October 2008 and January 2009. In this paper we present in great detail the evolution of the temporal and spectral characteristics of the persistent total and pulsed emission of 1E 1547.0-5408 between ~1 and 300 keV starting in October 3, 2008, and ending in January 2011. We analyzed data collected with the Rossi X-ray Timing Explorer, the International Gamma-Ray Astrophysics Laboratory and the Swift satellite.

The statistical analysis and the spherical wavelet analysis of the SDSS DR7 quasars distribution and of the WMAP CMB anisotropy are performed. They revealed the qualitative agreement between the angular power spectrum of CMB and the angular power spectrum of the quasar distribution on the celestial sphere. The angular correlation function and the angular power spectrum of the quasar distribution may be described by the power laws. The large quasar groups are discovered and they form the fractal set: the relation between their angular size and a number of quasar groups with this size is characterized by a power-law with fractal dimension 2.08.

The Sch\"onberg-Chandrasekhar (SC) limit is a well-established result in the understanding of stellar evolution. It provides an estimate of the point at which an evolved isothermal core embedded in an extended envelope begins to contract. We investigate contours of constant fractional mass in terms of homology invariant variables U and V and find that the SC limit exists because the isothermal core solution does not intersect all the contours for an envelope with polytropic index 3. We find that this analysis also applies to similar limits in the literature including the inner mass limit for polytropic models of quasi-stars. Consequently, any core solution that does not intersect all the fractional mass contours exhibits an associated limit and we identify several relevant cases where this is so. We show that a composite polytrope is at a fractional core mass limit when its core solution touches but does not cross the contour of the corresponding fractional core mass. We apply this test to realistic models of helium stars and find that stars typically expand when their cores are near a mass limit. Furthermore, it appears that stars that evolve into giants have always first exceeded an SC-like limit.

Techniques to improve the data quality of interferometric radio observations are considered. Fundaments of fringe frequencies in the uv-plane are discussed and filters are used to attenuate radio-frequency interference (RFI) and off-axis sources. Several new applications of filters are introduced and tested. A low-pass filter in time and frequency direction on single baseline data is successfully used to lower the noise in the area of interest and to remove sidelobes coming from unmodelled off-axis sources and RFI. Related side effects of data integration, averaging and gridding are analysed, and shown to be able to cause ghosts and an increase in noise, especially when using long baselines or interferometric elements that have a large field of view. A novel projected fringe low-pass filter is shown to be potentially useful for first order source separation. Initial tests show that the filters can be several factors faster compared to common source separation techniques such as peeling and a variant of peeling that is currently being tested on LOFAR observations called "demixed peeling". Further testing is required to support the performance of the filters.

This paper studies the connection between the relativistic number density of galaxies down the past light cone in a Friedmann-Lemaitre-Robertson-Walker spacetime with non-vanishing cosmological constant and the galaxy luminosity function (LF) data. It extends the redshift range of previous results presented in Albani et al. (2007, arXiv:astro-ph/0611032) where the galaxy distribution was studied out to z=1. Observational inhomogeneities were detected at this range. This research also searches for LF evolution in the context of the framework advanced by Ribeiro and Stoeger (2003, arXiv:astro-ph/0304094), further developing the theory linking relativistic cosmology theory and LF data. Selection functions are obtained using the Schechter parameters and redshift parametrization of the galaxy luminosity functions obtained from an I-band selected dataset of the FORS Deep Field galaxy survey in the redshift range 0.5<z<5.0 for its blue bands and 0.75<z<3.0 for its red ones. Differential number counts, densities and other related observables are obtained, and then used with the calculated selection functions to study the empirical radial distribution of the galaxies in a fully relativistic framework. The redshift range of the dataset used in this work, which is up to five times larger than the one used in previous studies, shows an increased relevance of the relativistic effects of expansion when compared to the evolution of the LF at the higher redshifts. The results also agree with the preliminary ones presented in Albani et al. (2007, arXiv:astro-ph/0611032), suggesting a power-law behavior of relativistic densities at high redshifts when they are defined in terms of the luminosity distance.

Type IIn and related supernovae show evidence for an interaction with a dense circumstellar medium that produces most of the supernova luminosity. X-ray emission from shock heated gas is crucial for the energetics of the interaction and can provide diagnostics on the shock interaction. Provided that the shock is at an optical depth tau_w\la c/v_s in the wind, where c is the speed of light and v_s is the shock velocity, a viscous shock is expected that heats the gas to a high temperature. For tau_w\ga 1, the shock wave is in the cooling regime; inverse Compton cooling dominates bremsstrahlung at higher densities and shock velocities. Although tau_w\ga 1, the optical depth through the emission zone is \la 1 so that inverse Compton effects do not give rise to significant X-ray emission. The electrons may not reach energy equipartition with the protons at higher shock velocities. As X-rays move out through the cool wind, the higher energy photons are lost to Compton degradation. If bremsstrahlung dominates the cooling and Compton losses are small, the energetic radiation can completely photoionize the preshock gas. However, inverse Compton cooling in the hot region and Compton degradation in the wind reduce the ionizing flux, so that complete photoionization is not obtained and photoabsorption by the wind further reduces the escaping X-ray flux. We conjecture that the combination of these effects led to the low observed X-ray flux from the optically luminous SN 2006gy.

We present the first galaxy scale lens catalog from the second Red-Sequence Cluster Survey (RCS2). The catalog contains 60 lensing system candidates comprised of Luminous Red Galaxy (LRG) lenses at 0.2 < z < 0.5 surrounded by blue arcs or apparent multiple images of background sources. The catalog is a valuable complement to previous galaxy-galaxy lens catalogs as it samples an intermediate lens redshift range and is composed by bright sources and lenses that allow easy follow-up for detailed analysis. Mass and mass-to-light ratio estimates reveal that the lens galaxies are massive (<M>~5.5x10e11 M_sun/h) and rich in dark matter (<M/L>~14 M_sun/L_sun,B*h). Even though a slight increasing trend in the mass-to-light ratio is observed from z=0.2 to z=0.5, current redshift and light profile measurements do not allow stringent constraints on the mass-to-light ratio evolution of LRGs.

We report on the development of search methods for point like and extended neutrino sources, utilizing the tracking and energy estimation capabilities of an underwater, Very Large Volume Neutrino Telescope (VLVnT). We demonstrate that the developed techniques offer a significant improvement on the telescope's discovery potential. We also present results on the potential of the Mediterranean KM3NeT to discover galactic, neutrino sources.

Observations and numerical simulations of galaxy clusters strongly indicate that the hot intracluster x-ray emitting gas is not spherically symmetric. In many earlier studies spherical symmetry has been assumed partly because of limited data quality, however new deep observations and instrumental designs will make it possible to go beyond that assumption. Measuring the temperature and density profiles are of interest when observing the x-ray gas, however the spatial shape of the gas itself also carries very useful information. For example, it is believed that the x-ray gas shape in the inner parts of galaxy clusters is greatly affected by feedback mechanisms, cooling and rotation, and measuring this shape can therefore indirectly provide information on these mechanisms. In this paper we present a novel method to measure the three-dimensional shape of the intracluster x-ray emitting gas. We can measure the shape from the x-ray observations only, i.e. the method does not require combination with independent measurements of e.g. the cluster mass or density profile. This is possible when one uses the full spectral information contained in the observed spectra. We demonstrate the method by measuring radial dependent shapes along the line of sight for CHANDRA mock data. We find that at least 10^6 photons are required to get a 5-{\sigma} detection of shape for an x-ray gas having realistic features such as a cool core and a double powerlaw for the density profile. We illustrate how Bayes' theorem is used to find the best fitting model of the x-ray gas, an analysis that is very important in a real observational scenario where the true spatial shape is unknown. Not including a shape in the fit may propagate to a mass bias if the x-ray is used to estimate the total cluster mass. We discuss this mass bias for a class of spacial shapes.

We calculate the first relativistic corrections to the Kompaneets equation for the evolution of the photon frequency distribution brought about by Compton scattering. The Lorentz invariant Boltzmann equation for electron-photon scattering is first specialized to isotropic electron and photon distributions, the squared scattering amplitude and the energy-momentum conserving delta function are each expanded to order v^/c^4, averages over the directions of the electron and photon momenta are then carried out, and finally an integration over the photon energy yields our Fokker- Planck equation. The Kompaneets equation, which involves only first- and second-order derivatives with respect to the photon energy, results from the order v^2/c^2 terms, while the first relativistic corrections of order v^4/c^4 introduce third- and fourth-order derivatives. We emphasize that our result holds when neither the electrons nor the photons are in thermal equilibrium; two effective temperatures characterize a general, non-thermal electron distribution. When the electrons are in thermal equilibrium our relativistic Fokker-Planck equation is in complete agreement with the most recent published results, but we both disagree with older work.

The distribution on the sky of the luminous objects to form at early times should be considerably different from the cosmic pattern seen today, with the differences diverging toward large angular scales and being particularly prominent between 5' to 1 deg. Although the individual sources at very high z are too faint to observe on their own, fluctuations in the intensity of the cosmic infrared background (CIB) will reflect the distribution of those early objects after foreground sources are removed to sufficiently faint levels. Previous observations out to scales as large as ~5' had seen the first indication of excess fluctuations above those expected from ordinary galaxies. We now extend the measurement of fluctuations to angular scales of ~ 1 deg using new data obtained in the course of the 2,000+ hour Spitzer Extended Deep Survey, where we find that the CIB fluctuations continue to diverge to more than 10 times those of ordinary galaxies. The detected CIB anisotropies are found to be significantly in excess of random instrument noise and known galaxy contributions on angular scales out to ~1 deg. The low shot noise levels remaining in the diffuse maps indicate that the large scale fluctuations arise from spatial clustering of faint sources well within the confusion noise. The spatial spectrum of these fluctuations is in reasonable agreement with simple fitting assuming that they originate in early populations spatially distributed according to the standard cosmological model (LCDM) at epochs coinciding with the first stars era. The alternative to this identification would require a new population never observed before, nor expected on theoretical grounds, but if true this would represent an important discovery in its own right.

The Kepler space telescope revealed new, unexpected phenomena in RR Lyrae stars: period doubling and the possible presence of additional modes. Identifying these modes is complicated because they blend in the rich features of the Fourier-spectrum. Our hydrodynamic calculations uncovered that a 'hidden' mode, the 9th overtone is involved in the period doubling phenomenon. The period of the overtone changes by up to 10 per cent compared to the linear value, indicating a very significant nonlinear period shift caused by its resonance with the fundamental mode. The observations also revealed weak peaks that may correspond to the first or second overtones. These additional modes are often coupled with period doubling. We investigated the possibilities and occurrences of mutual resonances between the fundamental mode and multiple overtones in our models. These theoretical findings can help interpreting the origin and nature of the 'hidden' modes may be found in the high quality light curves of space observatories.

We present fast timing photometric observations of the intermediate polar V2069 Cygni (RX J2123.7+4217) using the Optical Timing Analyzer (OPTIMA) at the 1.3 m telescope of Skinakas Observatory. The optical (450-950 nm) light curve of V2069 Cygni was measured with sub-second resolution for the first time during July 2009 and revealed a double-peaked pulsation with a period of 743.38 +0.25. A similar double-peaked modulation was found in the simultaneous Swift satellite observations. We suggest that this period represents the spin of the white dwarf accretor. Moreover, we present the results from a detailed analysis of the XMM-Newton observation that also shows a double-peaked modulation, however shifted in phase, with 742.35 +0.23 s period. The X-ray spectra obtained from the XMM-Newton EPIC (European Photon Imaging Camera) instruments were modelled by a plasma emission and a soft black body component with a partial covering photo-electric absorption model with covering fraction of 0.65. An additional Gaussian emission line at 6.385 keV with an equivalent width of 243 eV is required to account for fluorescent emission from neutral iron. The iron fluorescence (~6.4 keV) and FeXXVI lines (~6.95 keV) are clearly resolved in the EPIC spectra. In the Porb-Pspin diagram of IPs, V2069 Cyg shows a low spin to orbit ratio of ~0.0276 in comparison with ~0.1 for other intermediate polars.

We present properties of individual and composite rest-UV spectra of continuum- and narrowband-selected star-forming galaxies (SFGs) at a redshift of 2<z<3.5 discovered by the MUSYC collaboration in the ECDF-S. Among our sample of 81 UV-bright SFGs, 59 have R<25.5, of which 32 have rest-frame equivalent widths W_{Ly{\alpha}}>20 {\AA}, the canonical limit to be classified as a LAE. We divide our dataset into subsamples based on properties we are able to measure for each individual galaxy: Ly{\alpha} equivalent width, rest-frame UV colors, and redshift. Among our subsample of galaxies with R<25.5, those with rest-frame W_{Ly{\alpha}}>20 {\AA} have bluer UV continua, weaker low-ionization interstellar absorption lines, weaker C IV absorption, and stronger Si II* nebular emission than those with W_{Ly{\alpha}}<20 {\AA}. We measure a typical velocity offset of {\Delta}v~600 km s$^{-1}$ between Ly{\alpha} emission and low-ionization absorption among our subsamples. We find that the interstellar component, as opposed to the stellar component, dominates the high-ionization absorption line profiles. We find the low- and high-ionization Si ionization states have similar kinematic properties, yet the low-ionization absorption is correlated with Ly$\alpha$ emission and the high-ionization absorption is not. These trends are consistent with outflowing neutral gas being in the form of neutral clouds embedded in ionized gas as previously suggested by \cite{Steidel2010}. Moreover, our galaxies with bluer UV colors have stronger Ly{\alpha} emission, weaker low-ionization absorption and more prominent nebular emission line profiles. Among our dataset, UV-bright galaxies with W_{Ly{\alpha}}>20 {\AA} exhibit weaker Ly{\alpha} emission at lower redshifts, although we caution that this could be caused by spectroscopic confirmation of low Ly{\alpha} equivalent width galaxies being harder at z~3 than z~2.

This paper is a brief review of the status of the search for astrophysical neutrinos of high energy. Its emphasis is on the search for a hard spectrum of neutrinos from the whole Northern sky above the steeply falling background of atmospheric neutrinos. Current limits are so low that they are beginning to constrain models of the origin of extragalactic cosmic rays. Systematic effects stemming from incomplete knowledge of the background of atmospheric neutrinos are discussed.