bluuebunny/crossref_metadata_2025 huggingface dataset:
The Radio and Infrared Luminosities of 3CR Radio Galaxies - Are They Correlated?
Authors: Yates M.G. , Miller L. , Peacock J.A.
Published: July 2016

The infrared photometric study of a sample of 90 3CR radio galaxies by Lilly & Longair (1984, hereafter LL) has demonstrated that the high redshift objects are brighter in the infrared than their low redshift counterparts; this has been interpreted as being entirely due to the evolution of their constituent stellar populations. There is however a great difference between the radio luminosities of the high and low redshift objects in this flux limited sample and we have therefore examined statistically the possibility of a correlation between the infrared and radio luminosities of these galaxies, the presence of which could bias our interpretation of the infrared Hubble diagram. We find that the radio and infrared luminosities do indeed correlate for the most powerful radio galaxies.
A Distance Scale from the IR Magnitude/HI Velocity Width Relation
Authors: Aaronson M.
Published: July 2016

A summary is given of recent work using the IR/H I method, arguably the best global distance indicator presently available. Reflex motion toward the microwave dipole anisotropy has been seen relative to a sample of nearby galaxy clusters; this result is contrasted with the somewhat divergent conclusions obtained by Burstein et al. from a similar study of elliptical galaxies. A best guess calibration of the IR/H I zero point continues to lead to a high value for the expansion rate. This finding cannot be explained by appealing to Malmquist bias, as demonstrated by a straightforward linearity test of the velocity-distance relation. However, all current estimates of the Hubble constant are plagued by the large uncertainties to the distances of nearby calibrating galaxies, a problem whose full solution probably must await the launch of the Hubble Space Telescope.
Non-Uniformities in the Hubble Flow: Results from a Survey of Elliptical Galaxies
Authors: Davies Roger L. , Burstein David , Dressler Alan , Faber S. M. , Lynden-Bell Donald , Terlevich Roberto , Wegner Gary
Published: July 2016

We have used a new distance estimator for elliptical galaxies to determine the peculiar velocities, with respect to a uniform Hubble flow, of approximately 400 galaxies. The relative distances of five clusters in common with those of Aaronson et al. (1981, 1986), based on the infrared Tully-Fisher relation for spirals, are in good agreement.

We do not see the reflex of the Local Group motion with respect to the microwave background out to recession velocities of 6000 km s−1. Rather, the frame of elliptical galaxies appears to be moving with respect to the microwave background with a velocity of 600 km s−1 towards 1 = 312°, b = +6°. This motion is consistent with a re-analysis of the Rubin et al. (1976) data on the magnitude-diameter relation for ScI galaxies and with the nearby and cluster samples of Aaronson et al. (1982, 1986).
Contributions to the Local Gravitational Field from Beyond the Virgo Supercluster
Authors: Yahil Amos
Published: July 2016

In the last decade, the inter-relation between the density structure and velocity perturbations in the local Virgo Supercluster (VSC) has provided a major means of determining the cosmological density parameter Ωo. The underlying dynamics, the so-called Virgocentric Flow Model (VFM), assumes that the relevant peculiar gravitational field in the VSC is dominated by the monopole term, due to material inside the VSC. Over the past year, however, this premise has been called into question, on both observational and theoretical grounds. It has become clear that the contributions to the local gravitational field from beyond the VSC cannot be neglected. The major new developments are summarized here. A more detailed review is given elsewhere (Yahil 1987).
Tracing Superclusters and Voids with Abell Clusters
Authors: Burns Jack O. , Batuski David J.
Published: July 2016

The structure within the distribution of rich clusters is described. In particular, the Pisces-Cetus region is shown to contain a dense supercluster, a long filament of galaxies and clusters, and a ring of 12 Abell clusters surrounding a diameter void.
Shape of Superclusters
Authors: Vettolani G. , Chincarini G. , de Souza R.E.
Published: July 2016

Attempts to measure structural parameters of superclusters are described. Catalogues of superclusters have been prepared using a percolation algorithm applied to a complete sample of UGC galaxies brighter than the 14.5 magnitude. Both a two dimensinal (projected) and a three dimensional approach have been tried. The (conservative) result is that superclusters are certainly not spherical. Probably the departure from sphericity is towards elongated cigar-like structers. No evidence of relative alignements of superclusters has been found.
An Analysis of Fifty-Five Bright Southern Clusters of Galaxies
Authors: Olowin R. P.
Published: July 2016

We present the results of an analysis of fifty-five bright clusters clusters of galaxies as a homogeneous sample taken from a new effort to catalogue galaxy clusters in the Southern Hemisphere. The positions of some 21,000 galaxies in clusters have been catalogued along with visual magnitudes, morphological types, position angles of extended objects and pertinent remarks. For all of the clusters, various cluster parameters have been determined and form the basis of comparative studies for these fundamental aggregates of matter in the universe.
Towards Understanding the Large-Scale Structure?
Authors: Dekel Avishai
Published: July 2016

Although some theories, such as that of cold dark matter, are quite successful in explaining certain aspects of the formation of structure, we seem not to approach a satisfactory theory which can easily account for all the observational constraints on all scales. Most difficult to explain are the indicated clustering of clusters and bulk velocities on very large scales, when considered together with the structure on galactic scales and the isotropy of the microwave background. If these observations are correct, the only scenarios that can work are hybrids of certain sorts, which involve somewhat ad hoc choices of parameters; they are not the theories that would have emerged naturally from first principles, and they do not satisfy the criteria of simplicity and elegancy. I will discuss the currently popular scenarios and the apparent difficulties they face.
Systematic Properties of Galaxies: Implications for Galaxy Formation
Authors: Okamura S. , Kodaira K. , Watanabe M.
Published: July 2016

We have compiled a data base of V-band two-dimensional luminosity distribution for 261 galaxies in the Virgo and the Ursa Major regions (Watanabe 1983) using the 105-cm Schmidt telescope at the Kiso Observatory, Tokyo Astronomical Observatory. This is one of the largest collections of homogeneous surface photometry available to date, though the sample is biased for bright and large galaxies with m(V)≤14mag and/or D2 6≥2′. Among the sample galaxies we have selected some 200 certain members (V0<3500km/s) of the Virgo cluster and the Ursa Major clouds and performed various analyses on them to investigate systematic properties of galaxies. The two clusterings lie at nearly equal distance of (m-M)∼31.1 (Aaronson and Mould 1983). In the present paper we discuss the result of spheroid (bulge)/disk decomposition and velocity-luminosity relation for galaxies.
Is There an Alignment of Quasars Near NGC 520?
Authors: Gosset E. , Surdej J. , Swings J.P.
Published: July 2016

Three statistical tests applied to 65 UV excess objects in the field of NGC 520 lead to no detection of any significant alignment.
A Possible Tired-Light Mechanism
Authors: Pecker Jean-Claude , Vigier Jean-Pierre
Published: July 2016

Recent developments in physics and astrophysics lead us to reintroduce a new tired-light mechanism, implying an interaction between a massive photon and the particles of Dirac's vacuum.
Elemental Abundances and Temperature Distributions in the Intra-cluster Medium of the Perseus Cluster
Authors: Ulmer M. P. , Cruddace R. G. , Fenimore E. , Snyder W. A. , Fritz G.
Published: July 2016

Temperatures and iron abundances in two distinct regions of the Perseus Cluster, based on X-ray observations made with SPARTAN 1, are reported. Iron abundance values relative to solar are and , and the temperatures are and for the regions 0′ to 5′ and 6′ to 20′ from the cluster center, respectively. The uncertainties are 90% confidence.
Tidal Triggering of Seyfert Galaxies and Quasars: Physical Sufficiency
Authors: Byrd G.G. , Valtonen M.J. , Sundelius B. , Valtaoja L.
Published: July 2016

Excess optical and radio emission in nuclei of Seyfert galaxies and quasars is observationally related to nearby companions. Dahari found Seyferts are more strongly perturbed tidally by companions than normal spirals are. QSO data suggests a similar relationship. Quasar and Seyfert activity are thought to be fueled by gas inflow to the nucleus. To study whether gravitational tides from companions cause inflow from the spiral's disk, we use a self-gravitating 60,000 particle disk in Miller's polar n-body program. The perturbation to produce levels of inflow required for activity matches Dahari's Seyfert triggering level. QSO's are also perturbed by observed companions more than necessary for high inflow. We reanalyze Dahari's data to find that at least the majority of Seyferts are in multiple systems. Tidal triggering thus could be the main cause of Seyfert activity.
Search for Structural Changes in the Cores of “Nearby” Radio Galaxies
Authors: Preuss E. , Alef W.
Published: July 2016

Recent VLBI observations of the central radio components in the lobe-dominated radio galaxies 3C111 (Götz et al. 1987) and 3C390.3 (Alef et al. 1987) show drastic changes in the structure of the compact emission regions. In 3C111 a jet-like feature with two knots and a flux density of 600 mJy which was visible in 1980.4 had disappeared in 1985.4. This implies “superluminal behaviour” with a characteristic speed of ≳ 3c. In 3C390.3, there is also evidence for superluminal motion: radio knots appear to be ejected from the core at a rate of about one every 4 years and move out with an apparent velocity of 4.1 c (Ho = 50 km/s/Mpc throughout this paper) in the direction of the north-west extended lobe.
The Cosmic Evolution of Quasars at High Redshifts
Authors: Véron P.
Published: July 2016

The analysis of all published slitless quasar surveys suggests that the space density of quasars increases quickly with redshift up to z ∼ 2.45, then drops abruptly by about a factor of five, increases again up to z ∼ 3.8 at least to drop once more below the present day limit of sensitivity.
A Multi-Colour Survey for High-Redshift Quasars
Authors: Warren S.J. , Hewett P.C. , Irwin M.J.
Published: July 2016

We describe how the application of techniques which utilise all the information contained in multi-colour surveys of stellar-like objects can be employed to detect quasars over an extended redshift range. The method is particularly effective for the identification of quasars with redshifts z>2.2 where the application of the ultra-violet excess criterion breaks down. Spectroscopy of a small sample of objects from the first survey field has resulted in the detection of two new faint quasars with redshifts z=3.42 and z=4.01 (ref. 1).
Quasars Disks and Cosmology
Authors: Netzer Hagai
Published: July 2016

Much of the optical and ultraviolet radiation of bright quasars may originate in a massive accretion disk around a central black hole. Most searches for the signature of such disks gave ambiguous results but lately there are new ideas that may lead to their discovery. In particular, the apparent brightness of thin disks depend on their inclination to the observer's line of sight and this may be detected by the equivalent width of some emission lines (Netzer 1985, 1986). This idea may change our view on the inner structure of quasars and other AGN. In addition, it points to a potential selection effect that has not been taken into account so far. Magnitude limited optical quasar samples may contain, preferentially, face-on disks, thus cosmological evolution based on such samples may be biased. There are other implications, especially to the observed correlation of Lop with Lx in quasars.
The Neutrino Mass and the Cellular Large Scale Structure of the Universe
Authors: Ruffini R. , Song D.J. , Taraglio S.
Published: July 2016

We show how within the theoretical framework of a Gamow cosmology with massive neutrinos, the observed correlation functions between galaxies and between clusters of galaxies, naturally lead to a “cellular” structure of the Universe. From the size of “elementary cells” we derive constraints on the value of the masses and chemical potentials of the cosmological “inos”. We outline a procedure to estimate the “effective” average mass density of the Universe. We predict also the angular size of the inhomogeneities to be expected in the cosmological black body radiation as remnants of this cellular structure. A possible relation of our model to a fractal structure is indicated.
Gravitational Lenses as Tools in Observational Cosmology
Authors: Canizares Claude R.
Published: July 2016

The study of gravitational lenses is intimately tied to observational cosmology. When we observe a gravitationally lensed quasar, we are viewing a single object along two or more neighboring paths (null geodesics) of cosmological dimensions (Figure 1). What we see depends on bulk properties of the universe, such as Ho and qo, on the large scale structure and inhomogeneities along the paths, and on the small scale structure in and around the primary deflector. Furthermore, the deflection of light depends on the gravitational field along the line of sight, so it is sensitive to all forms of matter: luminous or dark, baryonic or exotic. Thus the images of gravitationally lensed quasars contain an imprint of the universe that is virtually inaccessible by any other means. The hope of decoding this imprint has stimulated observers and theorists to expend many thousands of hours of telescope time, computer time and cogitation on the elucidation of gravitational lens properties.
Absorption Line Systems at z > 3 in the QSO 2000-330
Authors: Hunstead R.W. , Pettini M. , Blades J.C. , Murdoch H.S.
Published: July 2016

This paper presents some preliminary results from analysis of our high-resolution (30–35 km/s FWHM) spectra of the Lyman α forest region in the z = 3.78 QSO 2000-330. These spectra were obtained at the Anglo-Australian Telescope over several observing seasons and have been analysed by fitting multiple-cloud Voigt profiles to Lyman series and heavy-element absorption lines. Two specific issues are addressed here:

(i)

The distribution of column densities, N(H I), and velocity dispersions, b, for hydrogen clouds in the interval zabs = 3.43–3.78;

(ii)

Heavy-element abundances in a system at zabs = 3.1723.
An Overview of AGN
Authors: Robson Ian
Published: July 2016

This paper gives an overview of the global properties of Active Galactic Nuclei, introducing and putting into context those areas that will be more fully described later in this volume. For the new entrant into AGN research, a semi-historical description of how the field developed is also given; showing how far we have come in a relatively short time. The pioneering work is now done, the big picture of how AGNs work is understood, we now embark on the search for the precise details of the emission mechanisms and their interrelations.
The Mid-Infrared Spectral Properties of Starburst Galaxies and Active Galactic Nuclei
Authors: Laurent O. , Mirabel I.F.
Published: July 2016

We present a new diagnostic tool based on mid-infrared spectra (5–16μm) for distinguishing the emission triggered by the active galactic nucleus (AGN) and by the star formation activity. We show that the AGN spectra, contrary to the starburst spectra, present an important continuum below 9μm and an absence of Unidentified Infrared Bands (UIBs).
HST Observations of the Jet of 3C120
Authors: Lelièvre G. , Bijaoui A. , Wlérick G.
Published: July 2016

The WFPC2 observations made by J. Westphal, in July 1995, allow us to confirm the existence of condensations O', O1 and O2; they are located at intersections between the radio jet and filaments emitting in the continuum and in the lines. The depolarization of the radio jet at the position of knot R1 is related to the interaction of the jet with a strongly ionized region of the galaxy. We also detect additional knots closer than 2.5” from the nucleus. The high angular resolution brings precise measurements in position and flux. The optical and radio positions are in good agreement and the radio/optical spectral indices of the knots are as expected in the case of synchrotron radiation.
Near-IR Polarimetry of the Obscured Nucleus in the Circinus Galaxy
Authors: M. Alexander D. , Ruiz M. , Young S. , Heisler C. , Lumsden S. , H. Hough J. , Bailey J.
Published: July 2016

We present J and K band imaging polarimetry and optical and K band spectropolarimetry of the Circinus galaxy. The imaging polarimetry shows a bipolar scattering cone in the J band and a more compact structure in the K band. The spectropolarimetry shows broad polarised hydrogen alpha in the optical, however broad lines are not detected in the K band. Analysis of the observations show that galactic and stellar processes dominate in the optical total and polarised flux whilst the nucleus dominates in the near-IR polarised flux. Modelling of the observations show that the small fraction of nuclear polarisation in the optical is due to electron scattering whilst the K band polarisation is dominated by dichroism.
The Study of Extended Radio Galaxies
Authors: Hovhannisyan M.A.
Published: July 2016

The jets of radio galaxies have an essential role in the formation of their extended components. However, in general, the physical characteristics of the jets differ from the characteristics of the extended components (the spectra, polarisation, density and so on).
Are Gamma-Ray Bursts Signals of Supermassive Black Hole Formation?
Authors: Abazajian K. , Fuller G. , Shi X.
Published: July 2016

The formation of supermassive black holes through the gravitational collapse of supermassive objects (M ≳ 5 × 104 M⊙) has been proposed as a source of cosmological γ-ray bursts. The major advantage of this model is that such collapses are far more energetic than stellar-remnant mergers. The major drawback of this idea is the severe baryon loading problem in one-dimensional models. We can show that the observed log N - log P (number vs. peak flux) distribution for gamma-ray bursts in the BATSE database is not inconsistent with an identification of supermassive object collapse as the origin of the gamma-ray bursts. This conclusion is valid for a range of plausible cosmological and γ-ray burst spectral parameters.
Accretion Disks and Star Formation
Authors: Collin Suzy , Zahn Jean-Paul
Published: July 2016

It is generally admitted that at distances larger than ˜ 104 gravitational radii accretion disks in AGN form a torus made of high velocity gaseous interacting clouds with a small filling factor. We propose here a completely different model for this region, in which unstable fragments give rise to protostars, all becoming massive stars after a rapid stage of accretion. These stars explode as supernovae, which produce strong outflows perpendicular to the disk and induce an outward transfer of angular momentum, as shown by the numerical simulations of Rozyczka, Bodenheimer and Lin (1995). So the supernovae themselves can sustain the inflow mass rate required by the AGN. Assuming that the star formation rate is proportional to the growth rate of the gravitational instabilities, one obtains a self-regulated accretion disk made of gas and stars in which the gas is maintained in a state close to gravitational instability. We show that the gaseous disk is able to support a large number of massive stars and supernovae while staying relatively homogeneous. This model could explain the high velocity metal enriched outflows implied by the presence of the broad absorption lines in quasars. It could also account for a pregalactic enrichment of the intergalactic medium, if black holes formed early in the Universe. Finally it could provide a triggering mechanism for starbursts in the central regions of galaxies.
Velocity Fields in Spiral Galaxies
Authors: Fridman A.M. , Khoruzhii O.V.
Published: July 2016

Discussed are various observable features of velocity fields in spiral galaxies. Main attention is paid to giant anticyclones and motions perpendicular to the disk plane.
Nuclear kpc-sized Disks of Spiral Galaxies
Authors: Zasov A.V. , Moiseev A.V.
Published: July 2016

The complex structure of nuclear disks of normal spiral galaxies is illustrated with the example of five galaxies, observed at the 6m telescope. The problem of gravitational stability of nuclear disks is briefly discussed.
The Nature of the UV-optical Continuum in Seyfert 2 Galaxies
Authors: Storchi-Bergmann Thaisa , R. Schmitt Henrique , Cid Fernandes Roberto
Published: July 2016

The nature of the UV-Optical continuum in Seyfert 2 galaxies is a matter of current debate, fundamental to which is the issue of characterizing and quantifying the stellar population contribution to the nuclear spectra. Using high S/N long-slit spectroscopy of a sample of 20 Seyfert 2 galaxies, we have applied a novel approach to investigate the nuclear stellar population in these galaxies. Our main results are: (1) the stellar populations in Seyfert 2 galaxies are varied, and in most cases cannot be adequately represented by an elliptical galaxy template, as done in previous works; (2) the central kpc of Seyfert 2's contain substantially larger proportions of 100 Myr stars than either elliptical galaxies or normal spirals of the same Hubble type. One important consequence of our findings is that the controversial nature of the so called “second” featureless continuum (FC2) in Seyfert 2s is most likely a result of inadequate evaluation of the stellar population.
Luminosity Correlation of the X-ray Selected Radio-Loud AGNs
Authors: Yuan Q. , Wu J. , Huang K.
Published: July 2016

This paper presents a test of the luminosity correlation of the X-ray selected radio-loud Active Galactic Nuclei (AGNs), based on a large sample constructed by combining our cross-identification of southern sky sources with the radio-loud sources in the northern hemisphere given by Brinkmann et al. (1995). All sources were detected both by the ROSAT All-Sky Survey and the radio surveys at 4.85 GHz. The broad band energy distribution confirms the presence of strong correlations between luminosities in the radio, optical, and X-ray bands which differ for quasars, seyferts, BL Lacs, and radio galaxies. The tight correlations between spectral indices αox and monochromatic luminosities at 5500 Å and 4.85 GHz are also shown.
Magnetic Field Strengths of GPS Radio Sources
Authors: Panajyan V. G.
Published: July 2016

GHz peaked spectrum radio sources (GPS) are believed to be a subclass of compact steep spectrum radio sources (CSS) with high frequency spectral indices α < −0.5 (5 ˜ vα), linear sizes of pc to kpc scale and turnover spectra near 1GHz. Due to the work of many radioastronomers during the past two decades many properties of CSS and GPS radio sources at present are known (O'Dea,C.P. et al.1998, and references therein).
Redshifts of New Galaxies
Authors: Arp Halton
Published: July 2016

Observations increasingly demonstrate the spatial association of high redshift objects with larger, low redshift galaxies. These companion objects show a continuous range of physical properties - from very compact, high redshift quasars, through smaller active galaxies and finally to only slightly smaller companion galaxies of slightly higher redshift. The shift in energy distribution from high to low makes it clear that are seeing an empirical evolution from newly created to older, more normal galaxies.

In order to account for the evolution of intrinsic redshift we must conclude that matter is initially born with low mass particles whose mass increase with time (age). This requires a physics which is nonlocal (Machian) and which is therefore more applicable to the cosmos than the Big Bang extrapolation of local physics. Ambartsumian's “superfluid” foresaw some of the properties of the new, low particle mass, protogalactic plasma which is required, demonstrating again the age-old lesson that open minded observation is much more powerful than theoretical assumptions.

Since the ejected plasma, which preferentially emerges along the minor axis of the parent galaxy, develops into an entire galaxy, accretion disks cannot supply sufficient material. New matter must be created within a “white hole” rather than bouncing old matter off a “black hole”.
The Gravitational Lens System B1030+074. Discovery and Follow-up
Authors: Xanthopoulos E. , A. Browne I. W. , King L. J. , Jackson N. J. , Marlow D. R. , Wilkinson P. N. , E. Koopmans L. V. , Patnaik A. R. , Porcas R. W.
Published: July 2016

We report the discovery of a new double image gravitational lens system B1030+074 which was found during the Jodrell Bank - VLA Astrometric Survey (JVAS). We have collected extensive radio data on the system using the VLA, MERLIN, the EVN and the VLBA as well as HST WFPC2 and NICMOS observations. The lensed images are separated by 1.56 arcseconds and their flux density ratio at centimetric wavelengths is approximately 14:1 although the ratio is slightly frequency dependent and the images appear to be time variable. The HST pictures show both the lensed images and the lensing galaxy close to the weaker image. The lensing galaxy has substructure which could be either part of the galaxy or a companion object. We have modeled B1030+074 using a Singular Isothermal Ellipsoid that yielded a time delay of 156/h50 days. This lens is likely to be suitable for the measurement of the Hubble constant.
Long Term X-ray Variability of Galactic Nuclei
Authors: Cunniffe J. , Meurs E.J.A.
Published: July 2016

We present some results on the long term variability of the X-ray emission from optically catalogued galaxies, especially in view of their nuclear properties. For this investigation we use data from the ROSAT PSPC archive. Some future directions are also discussed.
Searching for Low-Mass Supermassive Black Holes
Authors: Cappellari Michele , Bertola Francesco , M. Corsini Enrico , Funes José G. , Pizzella Alessandro , Vega Beltrán Juan C.
Published: July 2016

It has become generally accepted that most or possibly all ellipticals and bulges of spirals harbor supermassive black holes in their center (see Ho 1998 for a recent review).
Simultaneous UBVRI Light Curves of the Seyfert Galaxy NGC 4151 During the Extraordinary Brightening in 1989–1996
Authors: Merkulova N. , Metik L. , Pronik I.
Published: July 2016

The nucleus of the Seyfert galaxy NGC 4151 is known to be variable in the optical on different timescales: from minutes to tens of years. A new cycle of activity of the nucleus is investigated from 1989.
A New Sample of Candidate GPS Radio Sources with Intermediate Flux Densities
Authors: A. Ohanian Gabriel
Published: July 2016

A new sample of faint Gigahertz Peaked Spectrum (GPS) sources is presented here as an addition to our previous one (Ohanian, 1995). Comparison of the results of investigation of these samples with those of previously studied brighter samples (e.g. O'Dea et al. 1991) will delineate the properties of GPS sources over a wide range of luminosity, redshift and rest frame peak frequency. This will give noticeable information relevant to their cosmological evolution and relationship with other classes of extragalactic radio sources.
Determination of the OB Stellar Population of IZw18 on the Basis of its Hγ and Hδ Absorption lines
Authors: Sinanyan A. , Kunth D. , Lequeux J. , Comte G. , Petrosian A.
Published: July 2016

On the basis of new spectroscopic observations of the blue compact dwarf galaxy IZw18 in the narrow spectral range between 4000Å and 4500Å absorption components of Hγ and Hδ lines were discovered. Equivalent widths of Hγ and Hδ lines have been measured. From available data the OB population of IZw18 was analyzed.
High-energy Emission from Supernovae and Remnants
Authors: Chevalier R. A.
Published: July 2016

An early burst of energetic radiation is expected from a supernova at the time of shock breakout. This emission has not been directly observed but has been inferred from the photoionization around SN 1987A. X-ray emission has been detected from core-collapse supernovae in the days to years after the explosion as they interact with their circumstellar winds. Young Galactic supernova remnants provide the possibility of determining the composition structure of the ejecta through X-ray spectroscopy. An exciting finding for older remnants is that a number of remnants that appear to be interacting with molecular gas may be sources of high-energy γ-ray emission. The clumpy structure of molecular clouds has implications for the structure expected in high-energy emission. Finally, the field of γ-ray-line spectroscopy is beginning to yield results relevant to the explosive nucleosynthesis of radionuclides in supernovae.
Ultrahigh Energy Cosmic-ray Accelerators
Authors: Olinto A. V.
Published: July 2016

The surprising lack of a high energy cutoff in the cosmic ray spectrum at the highest energies, together with an apparently isotropic distribution of arrival directions, have strongly challenged most models proposed for the acceleration of ultrahigh energy cosmic rays. Young neutron star winds may be able to explain the mystery. We discuss this recent proposal after summarizing the observational challenge and plausible acceleration sites. Young neutrons star winds differ from alternative models in the predictions for composition, spectrum, and angular distribution, which will be tested in future experiments.
Collisionless Halos Around Black Holes
Authors: Gruzinov A.
Published: July 2016

When a black hole accretes slowly, the radiative cooling of the infalling gas is weak and the accretion disk does not form. A hot, collisionless, quasi-spherical halo is formed instead. The properties of such halos are discussed. The rate of accretion, the radiative efficiency, and the temperature and density near the hole are evaluated.
Gamma-ray Bursts and Afterglow
Authors: Sari R.
Published: July 2016

The origin of GRBs has been a mystery for almost 30 years. Their sources emit a huge amount of energy on short time scales, and the process involves extreme relativistic motion with a bulk Lorentz factor of at least a few hundred. In the last two years, “afterglow” emission in X-ray, optical, IR, and radio was detected. The afterglow can be measured up to months and even years after the few-seconds GRB. We review the theories for the γ-ray emission and its afterglow, and show that these are strongly supported by observations. A recent detection of optical emission simultaneous with the GRB agrees well with theoretical predictions and further constrains the free parameters of the models. We discuss the evidence that some of the bursts are jets and discuss the prospects of polarization measurements.
Hypernovae: SNe 1997ef, 1998bw, and 1997cy
Authors: Nakamura T. , Maeda K. , Iwamoto K. , Suzuki T. , Nomoto K. , Mazzali P. A. , Turatto M. , Danziger I. J. , Patat F.
Published: July 2016

We discuss the properties of the very energetic Type Ic supernovae (SNe Ic) 1998bw and 1997ef, and of Type IIn supernova (SN IIn) 1997cy. SNe Ic 1998bw and 1997ef are characterized by their large luminosity and very broad spectral features. Their observed properties can be explained if they are very energetic SN explosions (EK ≳ 1 × 1052 erg), originating probably from the core collapse of the bare C+O cores of massive stars (~ 30–40M⊙). At late times, both the light curve and the spectra suggest that the explosion may have been asymmetric; this may help us understand the claimed connection with GRBs. Type IIn SN 1997cy is even more luminous than SN 998bw, and the light curve declines more slowly than the 56Co decay. We model such a light curve with circumstellar interaction, which requires the explosion energy of ~ 5 × 1052 erg. Because these kinetic energies of explosion are much larger than in normal core-collapse SNe, we call objects like these SNe “hypernovae”.
Compton Scattering, Pair Annihilation, and Pair Production in a Plasma
Authors: Krishan V.
Published: July 2016

The square of the four-momentum of a photon in vacuum is zero. However, in an unmagnetized plasma, it is equal to the square of the plasma frequency. Further, the electron-photon coupling vertex is modified in a plasma to include the effect of the plasma medium. I calculate the cross sections of three processes in a plasma—Compton scattering and electron-positron pair annihilation and production. At high plasma densities, the cross sections are found to change significantly. Such high plasma densities exist in several astrophysical sources.
Stochastic Acceleration and Nonthermal Radiation in Clusters of Galaxies
Authors: Blasi P. , Olinto A.
Published: July 2016

We study the possibility that the recently detected hard X-ray excess from some clusters of galaxies is due to bremsstrahlung emission of a nonthermal tail in the electron distribution produced by stochastic acceleration in a background of MHD waves. We find that this scenario requires an overall level of fluctuations which is only δB2/B2~ 3% for a magnetic fieldBon the order of μG. Despite the reasonable values for these parameters, a large rate of injection of waves is needed to compensate the damping of the waves.
Pulsar Geometrodynamics: Relativistic Radiative Plasma Theory and its Associated Quantum Phenomena
Authors: Costa A. A. da
Published: July 2016

Plasma motion in pulsar magnetospheres is quasi-classical due to curvature radiation of highly energetic gamma-ray photons, implying an extension to the kinetic theory of plasmas. But with high energies involved, other quantum radiative processes become important in the context of vacuum (quantum) electrodynamics.
Primordial Flares, Flux Tubes, and Gamma-ray Bursts
Authors: Hiremath K. M.
Published: July 2016

Given the prevailing physical conditions in the cosmic environment, the similarity of solar transients and cosmic gamma-ray bursts suggests that the most promising energy source for the latter may be primordial flares, which derive energy from magnetic reconnection.
Hidden Blazars In Radio Loud Quasars?
Authors: Ma F.
Published: July 2016

We present the initial results from our search for hidden blazars via CIV emission line variability among radio loud quasars. The implications on models of quasar Broad Emission Line Regions are discussed, and we focus on the tidally disrupted star model.
Methods and Results of Estimating Light Pollution in the Flemish Region of Belgium
Authors: Vandewalle J. , Knapen Dirk , Polfliet Tim , Dejonghe H.
Published: July 2016

In the Flemish region of Belgium, yearly environmental reports (MIRA) are made on the status and evolution of the environment and its policy. Since 1996 light pollution and light impediment are among the topics considered. By using indicators which can be compared in the different reports it is possible to estimate the evolution of light pollution and light impediment. Suggested changes in lighting policies could save the Flemish region as much as 18 million EURO per year.
The Situation of Light Pollution in Germany
Authors: Hänel Andreas
Published: July 2016

The central European climate in Germany is not ideal for serious astronomical observations. Increasing light pollution hampers thousands of amateur astronomers and millions of people from seeing starry skies and the Milky Way.

To study the sources of light pollution, we estimate the increase of light pollution in Osnabrück, a town of about 160,000 inhabitants located in northwestern Germany. We try to extrapolate these statistical data to Germany and discuss possible reasons for increasing light pollution though the energy consumption stagnates. Some enthusiasts of the German amateur association “Vereinigung der Sternfreunde” have formed a working group DARK SKY to exchange information on this matter. Finally, we present some activities to make the public aware of the problem.
Economic Imperative versus Efforts for Preserving an Astronomical Site
Authors: Malasan Hakim L. , Senja Moch. Arief , Hidayat Bambang , Raharto Moedji
Published: July 2016

In this paper we report the gradual change of the physical environment of the Bosscha Observatory in Lembang, Indonesia. From photometric observations carried out in 1982 through 1993 we found a slight increase of the aerosol content in the atmosphere. However, light pollution from the expanding city of Bandung (pop. 2 × 106; 10 km away at 600 m altitude below the Observatory) has produced significant light scattering at zenith distances greater than 55° toward the south.
Aviation and Jet Contrails: Impact on Astronomy
Authors: Pedersen H.
Published: July 2016

Attention is drawn to aspects of aviation that have a detrimental effect on ground-based astronomy. Depending on observing methods, science data can be influenced by an aircraft's emission of light, its thermal emission, exhaust products and condensation trail. Although these effects are mostly short-lasting for a given observing direction, they can be highly significant, and influence time-resolved astronomical observations. While the very young contrails can easily be recognized by ground-based or spaceborne observations, concern should also be given to older (hours, days) contrails, which have lost their characteristic linear shape. Contrails may grow to widths of tens of kilometers, and become almost indistinguishable from natural cirrus. As aviation increases, this may imply fewer photometric nights, in particular in the northern hemisphere, where by far the largest fuel consumption takes place.
UN Discussions of Space Debris Issues
Authors: Perek Lubos
Published: July 2016

The role and activities of COPUOS, the UN Committee for the Peaceful Uses of Outer Space, are briefly described.
Impact of Space Debris and Space Reflectors on Ground-Based Astronomy
Authors: McNally D.
Published: July 2016

Astronomical fields under observation are being increasingly crossed by satellites. Such crossings either leave a “trail” on a photographic or CCD image, or corrupt a photographic observation. Such trailing/corruption may render an observation useless for scientific analysis. There is also the much more serious problem posed by suggestions to put solar reflectors in space for Earth illumination, artistic, celebratory or advertising purposes and, by extension, to longer term suggestions of ways to utilise dark time rather than twilight time. It is only a matter of time until the solar reflector becomes proven technology. The time left for decisive action may be very short.
The Future of Radio Astronomy: Options for Dealing with Human Generated Interference
Authors: Ekers R. D. , Bell J. F.
Published: July 2016

Radio astronomy provides a unique window on the universe, allowing us to study non-thermal processes (e.g. galactic nuclei, quasars, pulsars) at the highest angular resolution using VLBI, with low opacity. It is the most interesting waveband for SETI searches. To date it has yielded three Nobel prizes (microwave background, pulsars, gravitational radiation). There are both exciting possibilities and substantial challenges for radio astronomy to remain at the cutting edge over the next three decades. New instruments like ALMA and the SKA will open up new science if the challenge of dealing with human generated interference can be met. We summarise some of the issues and technological developments that will be essential to the future success of radio astronomy.
Utilization of the Radiofrequency Spectrum above 1 GHz by Passive Services
Authors: Pardo Juan R. , Encrenaz Pierre J. , Breton Daniel
Published: July 2016

Microwave atmospheric radiometry and radio, mm and sub-mm astronomy are “passive” services, i.e. not involved in any man-made transmission but only concerned with the reception of naturally occurring radio waves. The intensity of the radiation received is not subject to human control, unlike the situation for active services. All active services operate in bands occupied by natural signals of atmospheric and cosmic origin and the active service tranmissions may be powerful enough to noticeably interfere with reception of those signals by scientific services. A conflict exists for the coexistence of active and passive services in many frequency bands, which leads to a need for regulating how to share the electromagnetic spectrum. This document gives an overview of the problems of frequency sharing in the longwave region of the electromagnetic spectrum (radio to submillimetre waves).
RFI Sentinel 2
Authors: Montebugnoli S. , Cecchi M. , Bortolotti C. , Roma M. , Mariotti S.
Published: July 2016

Nowadays we have a massively increasing use of radio techniques in a wide variety of application fields. Meanwhile state-of-the-art receiver technology dramatically increases the sensitivity of modern radio telescopes. This situation produces a worrying vulnerability of ground-based radio telescopes to Radio Frequency Interference (RFI). In order to monitor the RFI scenario within the frequency bands reserved for radio astronomy activities, a monitoring system, based on a quite new approach, has been developed and is presented here.
Radio Interference in Astronomical Observatories of China
Authors: Peng B. , Nan R. , Piao T. , Jiang D. , Su Y. , Strom R. G. , Wu S. , Zhang X. , Zhu L. , Liu X.
Published: July 2016

We first very briefly introduce the major radio facilities for astronomical research in China, and then report on the present interference situation at major radio observatories. Some of the radio interference problems are caused by paging services, mobile phone satellites, telemetry services for power supply, waterpower and earthquake activity, or radar systems, but some causes are unknown. In the worst case, harmful to radio astronomy, the Sesan VLBI station has not been able to do any observations at 92 cm due to serious radio interference problems since 1992. Still more serious interference coming from satellites can be expected in the next decade. International efforts on frequency protection should be urgently pursued if ground-based radio astronomy is to survive.
Origin of Major L-Band Interference Received by the HALCA Space Radio Telescope
Authors: Lioubtchenko S. Yu. , Popov M. V. , Hirabayashi H. , Kobayashi H.
Published: July 2016

About 40 hours of observing data received by the space radio telescope HALCA at L-band (1.6 GHz) were analyzed in order to investigate interference received by the space radio telescope. Autocorrelation spectra for this study were specially prepared at the DRAO S2-correlator with a 7.8125 kHz frequency resolution in each 16 MHz channel. It was found that during 20% of the observing time the interfering signal was above the tolerable level of 1% of total receiver noise in a 16 MHz channel. The major source of interference is identified with uplink communication from ships to geostationary satellites in the International Maritime Satellite service (INMARSAT). The frequency range allocated for INMARSAT is 1636.5–1645.0 MHz. INMARSAT uses four geostationary satellites, two of which are located above the Atlantic Ocean where the strongest interference was observed. To avoid this interference it is recommended to move the HALCA observing frequency range from the currently used 1634–1666 MHz to 1645–1677 MHz. A simple criterion is proposed to predict harmful interference from INMARSAT. This criterion may be used in scheduling of future HALCA observations at L-band.
Physical Properties of Molecular Envelopes in Low-Mass Star-Forming Regions
Authors: Ohashi Nagayoshi
Published: July 2016

We have carried out interferometric observations of pre-protostellar and protostellar envelopes in Taurus. Protostellar envelopes are dense gaseous condensations with young stellar objects or protostars, while pre-protostellar envelopes are those without any known young stellar objects. Five pre-protostellar envelopes have been observed in CCS JN=32–21, showing flattened and clumpy structures of the envelopes. The observed CCS spectra show moderately narrow line widths, ~0.1 to ~0.35 km s–1. One pre-protostellar envelope, L1544, shows a remarkable velocity pattern, which can be explained in terms of infall and rotation. Our C18O J=1–0 observations of 8 protostellar envelopes show that they have also flattened structures like pre-protostellar envelopes but no clumpy structures. Four out the eight envelopes show velocity patterns that can be explained by motions of infall (and rotation). Physical properties of pre-protostellar and protostellar envelopes are discussed in detail.
Overview of Grain Models
Authors: Witt Adolf N.
Published: July 2016

The properties of interstellar grains can now be defined by a rapidly growing wealth of observational data. We rely upon models to combine these data with unobserved properties such as the size distribution of grains, their structure and shape, and their detailed chemical composition, in a self-consistent manner. I will review the observational constraints which define the boundaries for possible models and will then summarize the features of the three quasi-comprehensive grain models most commonly referred to in the current literature. I will conclude by discussing recent work dealing with single aspects of interstellar grains and the phenomena attributed to them.
Evolution of Gas and Dust in Circumstellar Disks
Authors: Koerner David W.
Published: July 2016

A clear understanding of the chemical processing of matter as it is transferred from a molecular cloud to a planetary system depends heavily on the physical conditions endured by gas and dust as these accrete onto a disk and are incorporated into planetary bodies. Reviewed here are astrophysical observations of circumstellar disks which trace their evolving properties. Accretion disks that are massive enough to produce a solar system like our own are typically larger than 100 AU. This suggests that the chemistry of a large fraction of the infalling material is not radically altered upon contact with a vigorous accretion shock. The mechanisms of accretion onto the star and eventual dispersal are not yet well understood, but timescales for the removal of gas and optically thick dust appear to be a few times 106 yrs. At later times, tenuous “debris disks” of dust remain around stars as old as a few times 108 yrs. Features in the morphology of the latter, such as inner holes, warps, and azimuthal asymmetries, are likely to be the result of the dynamical influence of large planetary bodies. Future observations will enlighten our understanding of chemical evolution and will focus on the search for disks in transition from a viscous accretion stage to one represented by a gas-free assemblage of colliding planetesimals. In the near future, comparative analysis of circumstellar dust and gas properties within a statistically significant sample of young stars at various ages will be possible with instrumentation such as SIRTF and SOFIA. Well-designed surveys will help place solar system analogs in a general context of a diversity of possible pathways for circumstellar evolution, one which encompasses the formation of stellar and brown-dwarf companions as well as planetary systems.