bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bidimensional [O III] λλ4959, 5007 Spectroscopy in the Circumnuclear Region of the Active Galaxy NGC 1068
Authors: García-Lorenzo B. , Arribas S. , Mediavilla E. , del Burgo C. 
Published: July 2016

AbstractWe present preliminary results about the velocity field of the ionized gas in the central region of NGC 1068, inferred from the [O III] λλ4959, 5007 emission lines. The data, 570 spectra in the inner 23″ × 18″ of this galaxy, were obtained with an optical fiber system which allows 2-D spectroscopy. The velocity field for the ionized gas inferred from the [O III] lines is in good agreement with recent results based on the Hα+[N II] lines.
An Objective-Prism Survey of Emission-Line Galaxies
Authors: Kim Chulhee 
Published: July 2016

AbstractIn order to discover emission-line galaxy (ELG) candidates towards the Hydra Void, an objective-prism survey was undertaken. As a first step, five fields were observed with the UK Schmidt Telescope, and we discovered a total of 33 candidates on a single prism plate through the [O III] λλ4959, 5007 emission feature.
Low-Luminosity Seyfert Nuclei
Authors: Ho Luis C. , Filippenko Alexei V. , Sargent Wallace L.W. 
Published: July 2016

AbstractWe describe a new sample of Seyfert nuclei discovered during the course of an optical spectroscopic survey of nearby galaxies. The majority of the objects, many recognized as AGNs for the first time, have luminosities much lower than those of classical Seyferts and populate the faint end of the AGN luminosity function. A significant fraction of the nuclei emit broad Hα emission qualitatively similar to the broad lines seen in classical Seyfert 1 nuclei and QSOs.
Spectral Properties of Parkes Flat-Spectrum Radio Sources
Authors: Drinkwater Michael J. , Francis Paul J. , Webster Rachel L. 
Published: July 2016

AbstractWe have constructed composite spectra of a large sample of flat-spectrum radio sources. The spectra are all very similar over a wide range of radio and optical properties, and are also similar to a composite of optically selected QSOs. We find, however, that the forbidden lines of the very reddest objects are anomalously strong.
Determination of the Gravitational Potential of Seyfert Cores from High-Resolution Spatial and Spectral Data
Authors: Wittkowski M. 
Published: July 2016

AbstractWe summarize the current state of our project to determine the gravitational potential in the innermost few hundred parsecs of Seyfert cores from observed line-of-sight velocities of molecular clouds. Therefore we distinguish between the observational part on the one hand and the theoretical aspects on the other. On the theoretical side the problem is lack of knowledge of the flow pattern and the spatial distribution of the clouds. We analyze the possibility of distinguishing between the different flow patterns and determining the mass distribution. On the observational side the problem is obtaining sufficiently high spatial and spectral resolution.
Macho Detection by Pulsar Timing Observation
Authors: Ohnishi Kouji , Hosokawa Mizuhiko , Fukushima Toshio , Takeuti Mine 
Published: July 2016

The magnitudes of some general relativistic effects depend on the mass of gravitating objects; therefore, these effects can be used for the stellar mass measurement. Several methods have been proposed; for example, the microlensing effect (Paczyński 1986), and the parallactic variation of gravitational deflection of the light from the source (Hosokawa et al. 1993).Recently some candidates for MACHOs – a kind of dark matter candidates in the Galactic halo – have been discovered by their microlensing effect, and their masses were estimated to be of the order of 0.1Mʘ, under many assumptions. Actual measurement of MACHO masses are important in specifying what kind of object the MACHO is.
Wide Beams from Young Pulsars (or One Pole for All)
Authors: Manchester R. N. 
Published: July 2016

AbstractPolarization observations show the existence of a well-defined group of young pulsars with highly linearly polarized mean pulse profiles. Many of these pulsars have interpulses. I suggest that both the main pulse and the interpulse in these pulsars are part of a very wide conal beam emitted along field lines emanating from a single magnetic pole. Such wide beams may be responsible for all interpulse emission.
Pulsar Polarization, Emission, and Beaming
Authors: Rankin Joanna M. 
Published: July 2016

AbstractThis paper discusses observational and analytical questions pertaining to the pulsar emission problem. A short outline of the area is given for those new to the subject. Some of the literature pertinent to pulsar polarization, emission and beaming, which has appeared over about the last five years is mentioned. There is a short discussion of efforts to carry out polarimetric observations of higher quality, and finally, there is a short discussion of recent work by the author and her colleagues.
Multi-Frequency Pulsar Polarimetry at High Frequencies
Authors: von Hoensbroech A. , Xilouris K. M. 
Published: July 2016

AbstractA sample of 62 pulsar profiles has been studied with full polarization information at high radio frequencies, aiming at studying the dependency of emission altitude at the deepest layers of pulsar magnetospheres. The emission is consistent with heights ranging between 1-2% of the light-cylinder-radius, while a slight radius-to-frequency mapping is evident.
Gamma-Ray Pulsar Emission Models
Authors: Harding Alice K. 
Published: July 2016

AbstractWith the increased sensitivity of gamma-ray detectors on the Compton Gamma-Ray Observatory (CGRO) the number of presently known gamma-ray pulsars has grown. The new detections are beginning to provide clues to the origin of the high-energy radiation in the form of emerging patterns and correlations among observed quantities such as gamma-ray efficiency and spectral index vs. age. But there are still many questions about the location of the emission and its relation to the radio, optical and X-ray pulses. This paper will review models for gamma-ray emission from pulsars and will examine how well the detailed predictions of these models account for the existing observations.
The Problem of Energy Transfer in the Crab Nebula
Authors: Machabeli G. , Mchedlishvili G. , Shapakidze D. 
Published: July 2016

AbstractThe possibility of Langmuir wave generation in electronpositron plasma is considered. As a result of induced scattering, these waves find themselves in the superluminal region. Thereby such waves can transfer energy to the Crab Nebula essentially without loss, where the remaining plasma creates condition of collapse of Langmuir waves. As a result, the tail of thee±distribution function stretchs out to Lorentz factors of the order of γ±≤ 109. Via synchrotron emission, particles of these energies can radiate X and γ - radiation.
The Galactic Electron Density Distribution
Authors: Weisberg Joel M. 
Published: July 2016

AbstractPulsars are excellent probes of the galactic free electron layer. Interstellar dispersion and scattering measurably affect the observed pulsar signals, thereby providing information on the distribution and density of the free electrons causing these phenomena.Primary calibration of galactic electron density models is achieved through adjusting their parameters to fit the observed dispersion of pulsars having independently measured distances. The distances are determined via kinematic analyses of HI absorption spectra, through angular or timing parallax measurements, and from associations with other objects of known distances.The models have become steadily more refined as the body of data upon which they are based has grown. Independent distance measurements continue to accrue. The discovery of pulsars in globular clusters provided high latitude lines of sight for probing the z-distribution (Reynolds 1989). Additional calibration has been provided through incorporation of interstellar scattering measurements into the modelling process (Cordeset al. 1991). Individual spiral arms are now explicitly modelled (Taylor &amp; Cordes 1993).While great progress has been achieved with these models, there are still uncertainties in modelling the electron density of the local region and the inner Galaxy, and in the z–distribution of the electron layer. Currently anticipated observations will help to resolve some of these issues.
Investigation of pulsar diffractive scintillation at 4.75 and 10.55 GHz
Authors: Malofeev V. , Shishov V. , Sieber W. , Jessner A. , Kramer M. , Wielebinski R. 
Published: July 2016

Many papers were in the past devoted to the investigation of the interstellar medium (ISM) with the help of pulsars, most of them studying the time and frequency structure of pulsar flux variations in the strong scintillation regime. Weak scintillation is typically found at cm- and dcm-wavelengths, but depends on distance so that the critical frequency (νc) increases with distance. Pulsar intensities weaken, however, at high frequencies, since as a rule pulsar spectra have spectral indices steeper than −1.5. This explains why there are practically no measurements of pulsars in the weak scintillation regime.We report in this paper on first measurements of the correlation function of pulsar intensity fluctuations, of the decorrelation timeτdand of the scintillation indexmdat high frequencies, i.e. at 4.75 and 10.55 GHz in the weak scintillation regime. The detail data analysis, theoretical relations and comparison with theory will presented by Malofeev et al. (1996).
On Galactic magnetic field derived from RMs of pulsars
Authors: Han J.L. , Qiao G.J. 
Published: July 2016

AbstractRMs of all 262 pulsars are used to see the large scale magnetic field of our Galaxy. We find that: (1). RMs of 91 pulsars at high galactic latitude (|b| &gt; 8.6°) show two toroidal magnetic rings antisymmetric with respect to galactic plane. These data shouldn’t be used for modelling the large scale field in Galactic disk; (2). pulsars at low galactic latitude are concentrated on the spiral arms; (3). the directions of fields have a similar pitch angle to that of spiral arms.
Dynamical and Microphysical Constraints on Accreting Magnetospheric Clouds in Active Galactic Nuclei
Authors: Kuncic Zdenka 
Published: July 2016

AbstractThe range of microphysical and dynamical timescales at the centres of Active Galactic Nuclei (AGN) is sufficiently wide to permit multiphase structure. In particular, very dense, cool clouds can coexist with a hot, magnetically-dominated plasma. The strong dynamical forces in this central magnetosphere can give rise to clouds so small that microphysical processes determine whether they can survive for long enough to produce potentially observable spectral signatures due to thermal reprocessing. Specific physical constraints on the scale sizes of such reprocessing clouds are examined. It is found that there exists a parameter subspace in the extreme high density regime for which gas can sustain cool temperatures whilst maintaining pressure equilibrium with the ambient magnetosphere.
Hydrodynamic Simulations of Wind-Accretion with Gradients
Authors: Ruffert M. 
Published: July 2016

AbstractI investigate the hydrodynamics of three-dimensional Bondi-Hoyle-Lyttleton accretion including velocity and density gradients in the incoming flow and determine how much angular momentum is accreted. A medium taken to be an ideal gas with an adiabatic index of 5/3 or 4/3 moves at supersonic speeds (Mach 3 and 10) past a totally absorbing sphere with a radius of 0.1 or 0.02 accretion radii. The velocity within the medium is given a gradient of 3% or 20% (over one accretion radius). I find that a substantial amount (0.1 to 0.7) of the specific angular momentum available within one accretion radius in the upstream flow actually is accreted. The amount is smaller for smaller accretor sizes. The flow is roughly just as unstable as in the previous models without gradients. The unstable flow is best seen in animated sequences.
Kilohertz QPO in Low Mass X-Ray Binaries: an Overview
Authors: van der Klis M. 
Published: July 2016

AbstractI review the current status of the investigations of the kilohertz quasi-periodic oscillations that have been discovered in low-mass Xray binaries (LMXBs) with NASA’s Rossi X-ray Timing Explorer (RXTE) since February 1996. Seven sources have now shown this new phenomenon, one Z source (Sco X–l) and 6 atoll sources (all X-ray bursters), and some patterns are beginning to emerge. The frequencies of the oscillations are between 500 and 1200 Hz. They can be coherent for more than 102 cycles, but a more typical coherence is several 101. Amplitudes are between 0.5 and 16% (rms) of the total flux. Most sources show double kHz peaks separated by a few 102 Hz, which move up and down in frequency together. In Sco X–l the peak frequencies systematically increase, and the peak separation systematically decreases, with Ṁ. In 4U 1728–34 a third oscillation is seen at a frequency equal to the difference frequency of the two kHz peaks, but only during X-ray bursts. A simple interpretation in terms of a beat-frequency model with the difference frequency being the neutron star’s spin, as suggested by this result, is inconsistent with the fact that in Sco X–l the peak separation varies.
X-Ray Observations Of SS 433 With ASCA
Authors: Kotani T. , Kawai N. , Matsuoka M. , Brinkmann W. 
Published: July 2016

AbstractSS 433 has been observed with ASCA for three years since the launch in 1993. The excellent energy resolution of ASCA revealed the Doppler-shifted emission lines from the both jets, though it had been generally accepted that the X-ray emitting region of the receding jet is hidden behind the accretion disk. Thus the estimation on the properties of the X-ray jet, such as length, temperature, and mass outflow rate, should be revised in accordance with the ASCA data. Modeling the jet as a radiating ballistic plasma, we determined these quantities. It is also tried to determine the mass of the system from a data covering an eclipse.
White Dwarf Masses in magnetic CVs: Multi-temperature Fits to Ginga data
Authors: Cropper Mark , Ramsay Gavin , Wu Kinwah 
Published: July 2016

AbstractWe have used the hard X-ray spectrum obtained from Ginga to determine the mass of the white dwarf primary star in 13 magnetic CV systems. Our model for the spectral fit includes the temperature and density structure in the post-shock accretion flow, taking into account the additional cooling of the cyclotron radiation. We obtain good fits to the data, and we compare our derived masses to those determined by other means.
Numerical Simulations of MHD Winds from Accretion Disks
Authors: Stone James M. 
Published: July 2016

AbstractThe contributions that time-dependent multidimensional numerical simulations have made to our understanding of MHD winds from accretion disks are reviewed. Current simulations can be divided into four categories: (1) axisymmetric global models, (2) axisymmetric simulations of the wind only, (3) three-dimensional local models, and (4) threedimensional global models. Results from each category are discussed. Current results indicate that weakly magnetized disks are turbulent, and that this turbulence is responsible for dynamo action which amplifies the disk field. These effects may have important consequences for the production of MHD winds. We discuss the feasibility of fully three-dimensional global models that can capture these effects in the future.
Infrared Jets from Protostars: The case of HH212
Authors: Zinnecker Hans , McCaughrean Mark J. 
Published: July 2016

AbstractWe describe the appearance and significance of HH212, the most symmetric two-sided molecular hydrogen jet/counterjet system yet discovered. This prototype embedded protostellar H2jet emanates from a low-luminosity isolated protostar in Orion. It exhibits matched pairs of knots and bow-shocks interpreted as arising from a time-variable source, which we take to indicate that protostellar accretion through the encircling disk is non-steady and pulsed.
Optical/Ultraviolet Continuum Polarization of AGN Accretion Disks
Authors: Blaes Omer , Agol Eric 
Published: July 2016

AbstractWe show how the effects of Faraday rotation and a detailed treatment of the radiative transfer can address various aspects of the polarization problem of AGN accretion disks. In particular, we show how accretion disks might explain the rises in polarization observed blueward of the Lyman edge in several quasars.
General Relativistic Simulation of Jet Formation from Magnetized Accretion Disk
Authors: Koide Shinji , Shibata Kazunari , Kudoh Takahiro 
Published: July 2016

AbstractRecently, superluminal motions are observed not only from active galactic nuclei but also in our Galaxy. These phenomena are explained as relativistic jets propagating almost toward us with Lorentz factor more than 2. For the formation of such a relativistic jet, magnetically driven mechanism around a black hole is most promising. We have extended the 2.5D Newtonian MHD jet model (Shibata & Uchida 1986) to general relativistic regime. For this purpose, we have developed a general relativistic magnetohydrodynamic (GRMHD) numerical code and applied it to the simulation of the magnetized accretion disk around a black hole. We have found the formation of magnetically driven jets with 86 percent of light velocity (i.e. Lorentz factor ~ 2.0).
Outflow Angles and Bulk Lorentz Factors for Different Categories of AGN
Authors: Guerra Erick. J. , Daly Ruth A. 
Published: July 2016

AbstractRelativistic outflows from AGN can be parameterized by θ, the angle subtended by the direction of the outflow and the line of sight to the observer, and γ, the bulk Lorentz factor of the outflow. The Doppler factor, δ, and the apparent speed in the plane of the sky, βapp, are combinations of θ and γ. The Doppler factor can be estimated using either the equipartition Doppler factor, δeq (Readhead 1994), or the inverse Compton Doppler factor, δIC. These Doppler factor estimates are combined with observed βapp to solve for θ and γ for different categories of AGN.Ghisellini et al. (1993) compute δIC for 105 compact radio sources, and Güijosa & Daly (1996) compute δeq for the same sample. Daly, Guerra, & Güijosa (1996) estimate θ and γ for the 43 sources that have βapp listed by Vermeulen & Cohen (1994) and δeq computed by Güijosa & Daly (1996).Solutions and errors for θ and γ are presented in Figures 1 and 2 using δeq and δIC respectively. Guerra & Daly (1996) discuss these estimates and errors in greater detail. These AGN fall into the following categories: BL Lacertae objects (BL Lacs), core-dominated high-polarization quasars (CDHPQ), core-dominated low-polarization quasars (CDLPQ), core-dominated quasars with no polarization information (CDQ(NPI)), lobe-dominated quasars (LDQ), and radio galaxies (RG).
Discovery of an X-Ray Off-State in the Supersoft Source CAL 83
Authors: Kahabka P. 
Published: July 2016

AbstractAn X-ray off state of CAL 83 has been observed in April 1996 with the ROSAT HRI three weeks after a normal on state. An upper limit for a linear decline time of the observed flux of ~20 days (and of an efolding decline time of ~6 days) is deduced. This decline may be due to the response of the white dwarf envelope to a temporary increased mass accretion rate giving rise to an envelope expansion. CAL 83 may resemble the recurrent supersoft LMC transient RX J0513.9–6951 with episodes of disappearance in X-rays.
Mass Flux and Toroidal Magnetic Field in Magnetically Driven Jets from Accretion Disks: Steady Solutions and Application to Jet/Wind in YSO
Authors: Kudoh T. , Shibata K. 
Published: July 2016

AbstractWe solved one-dimensional steady and axisymmetric magnetohydrodynamical (MHD) equations to study basic properties of astrophysical jets from accretion disks. We found that the mass flux of the jets depends on the poloidal magnetic field strength of the disk. The mass loss rates observed in T Tauri winds will constrain the physical quantities in the accretion disks.
Infrared Emission Around Cyg X-3
Authors: Ogley R.N. , Bell Burnell S.J. , Fender R.P. 
Published: July 2016

AbstractWe present UKIRT infrared images of the X-ray binary Cygnus X-3. We address the possibility of extended infrared emission and show that it could be either warm circumstellar material or a star near the binary’s line of sight.
Mid-infrared Observations of Magnetic Fields in the Disks of Bi-Polar Outflow Sources
Authors: Smith Craig H. , Wright Christopher M. , Aitken David K. , Roche Patrick F. 
Published: July 2016

AbstractWe present the results from mid-infrared spectro-polarimetric observations of a number of bi-polar outflow sources. The specto-polarimetric data provides information on the polarization mechanism and the magnetic field direction. The field direction in the disks of the observed sources is most often normal to the ambient field direction and lies in the plane of the disk, indicating a toroidal rather than poloidal field configuration.
Optical Signatures of Reprocessing from Hercules X-l
Authors: Still M. D. , Reynolds A. P. , Quaintrell H. , Roche P. , Chakrabarty D. , Levine S. E. 
Published: July 2016

AbstractThe mechanism providing the 35-day period found in optical and X-ray light curves of the eclipsing low-mass X-ray binary Her X-l is considered to be the precession of a tilted and twisted accretion disc about the neutron star. We have obtained spectrophotometric observations of this system. The majority of line absorption and emission originates on or near the mass-losing primary, with distributions over the inner face of the star consistent with irradiation from the environs of the compact object. After suitable corrections for heating, the neutron star is found have a mass of 1.6±0.3M⊙, in contrast to the last radial velocity study which found a value less than 1.0 M⊙ . Rotational velocity measurements, while insufficiently precise to reject the older mass estimate, suggest that the rotational period of HZ Her differs from the synchronous rate by no more than 20%. Using a recently determined figure for the effective temperature of the unheated face, the distance to Her X-l is estimated at 6.7±0.4kpc, higher than prior estimates. The systemic velocity is found to be –69±6km s−1. In order to to determine the plausibility of the twisted disc model we reconstruct the expected shadow of the disc across the heated inner face of the donor star to compare with observation. Large scale emission structure is reproduced, but the model fails to synthesize finer observational details. HeII λ4686 Å emission is detected and found to be distributed closely about the neutron star, and is a likely tracer of the accretion flow.
Wind Accretion in Separated Binaries
Authors: Walder R. 
Published: July 2016

In the framework of Euler flows, I present simulations of wind accretion in well separated binaries for three different cases: Cygnus X-3, a high mass X-ray binary (see e.g. Schmutz et al. 1996), ζ Aurigae, a system showing strong atmospheric eclipse effects (see e.g. Griffin et al. 1990), and the generic barium star model of Theuns and Jorissen (1993), which is recomputed here with a different numerical method (a MUSCL-type integrator, incorporated in our AMRCART code). These simulations represent a first, small sample out of the large parameter space of wind accretion in separated binaries (see Table 1).On the orbital scale, the vorticity of the flow is due to the orbital motion of the stars. It is particularly large for the case where the wind velocity is comparable to the orbital speed of the stars (see Fig. 1). In the vicinity of the accreting star, the vorticity is determined by the accretion process. With two strong vortices above and below the accretor (with respect to the orbital plane), the flow resembles the flow out of a bath tub. On a smaller scale, one finds even more vorticity: The flow is highly turbulent. Such turbulence and the shear flows in the large scale vortices cannot be well captured by an Euler flow model. A next step of improvement would be the use of an appropriate MHD turbulence model.