bluuebunny/crossref_metadata_2025_split huggingface dataset:
An HI Survey of LSB galaxies selected from the APM Survey
Authors: Côté Stéphanie , Broadhurst Tom , Loveday Jon , Kolind Shannon 
Published: July 2016

AbstractWe present preliminary results of a neutral hydrogen (HI) redshift survey to find Low Surface Brightness (LSB) galaxies in the very nearby universe. Our sample consists of all galaxies in the APM catalog (Maddox et al. 1990) with a mean surface brightness of μ ≥ 24 mag/arcsec2, down to a magnitude limit of bj ≤ 17. With the Parkes 64m radiotelescope 35 objects were detected at v < 4300 km s−1. The resulting luminosity function, HI mass function, and for the first time total mass function are presented. It is found that LSBs make a negligible contribution to the overall integrated luminosity, HI mass, and total mass contained in galaxies.
Observational Properties of Triple Galaxies
Authors: Karachentsev I. D. 
Published: July 2016

AbstractThis report presents basic observational parameters for galaxy triplets selected by criterion of their isolation on the sky (=Catalog of Triple Galaxies, Karachentseva et al, 1979). The CTG sample is compared with a sample of wide triple systems from Nearby Galaxies Catalog (Tully, 1988) as well from a new whole-sky catalog of small galaxy groups in the Local Supercluster (Makarov & Karachentsev, 2000). For all the samples their medians of the virial mass-to-luminosity ratio lie in a narrow range, 31 <Mvir/L< 36 (M⊙/L⊙), while the medians of the crossing time occupy a wider range, 0.07 <Tcross< 0.37 (in 1/Hunits).
The effects of galaxy winds on small galaxy groups
Authors: Helsdon Stephen F. , Ponman Trevor J. 
Published: July 2016

AbstractWe present the largest survey to date of the X-ray properties of loose groups. We derive relations between X-ray luminosity, temperature and velocity dispersion, and also examine the surface brightness profiles of these systems. We find significant departures from the trends seen in galaxy clusters, which we interpret as arising from the effect of galaxy winds, and we briefly compare the properties of these loose groups with those of compact groups.
Collisional Ring Galaxies in Small Groups
Authors: Horellou C. 
Published: July 2016

AbstractThe probability of plunging orbits is enhanced in groups of galaxies and indeed, observations show that ring galaxies, which are believed to form when a galaxy passes through the center of a larger rotating disk, are often found in small groups. Numerical simulations combined with a knowledge of the large-scale H I distribution provide strong constraints on the dynamical history of these systems and on the identity of the intruder. Here we present a numerical model of the Cartwheel galaxy which supports the suggestion that the most distant companion is the intruder. We also present high-resolution H I observations of the more irregular system Arp 119 that reveal a possible connection to the most distant companion.
Galaxies in the M81 Group and IC342/Maffei Complex: The Structure and Stellar Populations
Authors: Drozdovsky Igor , Nikolay Tikhonov 
Published: July 2016

AbstractWe present optical V, R, and I-band observations on the structure and stellar populations of the M81 Group and IC342/Maffei Complex galaxies. The images have been obtained with the 6m BTA and 2.5m Nordic optical telescopes. Stellar photometry of several galaxies in these groups have been performed. The resulting colour-magnitude diagrams reveal the morphology of different stellar populations in these systems. Distances to the galaxies have been estimated from the tip of the red giant branch (TRGB), or from the brightest blue and red stars. For some galaxies the reddening, metallicity and surface profile parameters have been measured. We describe in more detail the results for four galaxies: IC 2574, Holmberg I, DDO 53 and IC 342. A more comprehensive project is underway.
Mass-to-Light Ratio Measurements of Galaxies, Groups, and Clusters using the Numerical Action Method
Authors: Shaya Ed , Peebles P. J. E. , Phelps Steven , Tully R. Brent 
Published: July 2016

AbstractThe numerical action variational method (NAM) is an elegant, non-chaotic technique for calculating the trajectories of gravitating systems in a cosmological context. It has been used extensively for establishing orbits of Local Group galaxies in a series of papers (Peebles 1989, 1990, 1994, 1995) and for the Local Supercluster (Shaya, Peebles, & Tully 1995).Our repertoir of tools include code that holds present distances constant and predicts possible redshifts, one that holds present redshifts constant and predicts possible distances, and one that varies masses of each mass tracer and simultaneously satisfies both distance and redshift.Our results indicate a Ω0 = 0.2, a mass-to-light ratio of field galaxies in the range of 100 M⊙/L⊙ in blue light (t0 = 11 Gyr with no cosmological constant), but for the Virgo Cluster, the value is 6 or 7 times higher. The higher values of Ω0 determined from using the IRAS galaxy distributions may be a result of under weighting this important mass component of the universe plus a poor correlation between cluster and field galaxy distributions.
Evidence for dark matter on different scales from the KLUN galaxy sample
Authors: Hanski M. O. , Teerikorpi P. , Ekholm T. , Theureau G. , Baryshev Yu. , Paturel G. , Lanoix P. 
Published: July 2016

The KLUN (Kinematics of the Local UNiverse) sample of 6600 spiral galaxies is used in studying dark matter on different scales:
•The Morphological Type dependence of the zero-point of the Tully-Fisher relation indicates mass to light ratio M/L ≈ 9 − 16 on galactic scales.•Preliminary results from a study of selection effects influencing double galaxies give a larger value M/L ≈ 30 − 50.•Study of the Perseus-Pisces supercluster, using Malmquist bias corrected TF distances and Tolman-Bondi solutions indicates M/L ≈ 200 − 600 for large clusters. Similar results were obtained in our previous work on Virgo galaxies.•Application of a modified version of Sandage-Tammann-Hardy test of the linearity of Hubble law inside the observed hierarchical (fractal) galaxy distribution up to 200 Mpc suggests that either Ω0 is very small (0.01) or the major part of the matter is uniformly distributed dark matter.
Co-rotating Photospheric Clouds in μ Centauri
Authors: Balona L.A. , James D. , Lawson W.A. , Shobbrook R.R. 
Published: July 2016

AbstractSeveral periods close to 0.5 d have been reported for μ Cen. We obtained over 300 echelle spectra and simultaneous multicolour photometry over a two-week period. We find that the period is 0.66 d and is, in fact, singly periodic. Greyscale images of many consecutive nights show moving features which do not repeat nightly, as may be expected for P = 0.5 d, but repeat approximately every alternate night. In spite of this, periodogram analysis of the radial velocity, as measured at the point of minimum intensity in the spectral line, does indeed show a 0.5-d period. The amplitude of this periodicity decreases during the course of the run. This seeming contradiction, as well as the apparent multiperiodicity, is due to the use of period finding techniques which exclude singly-periodic solutions of a complex nature. We interpret the variations as due to two, co-rotating, circumstellar clouds distributed around the star, such that they are separated by a time interval of 0.5 d. It appears that μ Cen is another example of the growing list of Be stars in which the periodicity is due to co-rotating photospheric clouds.
Non-radial Pulsation Modeling of ω (28) CMa
Authors: Maintz M. , Rivinius Th. , Tubbesing S. , Wolf B. , Štefl S. , Baade D. 
Published: July 2016

AbstractAdopting non-radial pulsation (nrp) the line profile variability lpv of several absorption lines of different ions was modeled for ω (28) CMa. The parameters suggested by Baade (1982) to characterise the pulsation could be confirmed. The pulsation period in the inertial frame was found to be negative, i.e. an actually retrograde mode appears prograde due to the rapid stellar rotation. The line profiles could be reproduced in detail including structures like spikes and ramps. They were identified as velocity effect due to the latitudinal component of the nrp velocity field υϑ in combination with low inclination i. In spite of small photometric variations (Štefl et al. 1999) the lpv of the absorption lines can be explained by nrp entirely.
Far-infrared Excesses in Classical Be Stars
Authors: Miroshnichenko A.S. , Bjorkman K.S. 
Published: July 2016

AbstractA sample of Be stars with large far-infrared excesses detected by IRAS is selected and their high-resolution IRAS images are examined. The far-infrared emission from most of them is marginally extended and is associated with the optical sources. Modeling of the stars’ spectral energy distributions allows us to rule out the infrared cirrus nature of the excesses. We suggest that the excesses are more likely due to circumstellar dust, possibly formed early in the evolution of the star.
B-type Emission-line Stars with Warm Circumstellar Dust
Authors: Sheikina T.A. , Miroshnichenko A.S. , Corporon P. 
Published: July 2016

AbstractWe selected a group of 11 B-type emission-line stars with large IR excesses, which show a steep flux decrease towards longer wavelengths. Analysis of their observational characteristics has been carried out on the basis of the data collected from literature, results of our recent photometric and high-resolution spectroscopic observations. Possible nature and evolutionary state of the group objects are discussed.
Optical and Near–Infrared Spectroscopy of the Emission Line Young Stellar Object Gy 2-18 (HHL 31)
Authors: Persi Paolo , Polcaro Vito Francesco , Bohigas Joaquin , Tapia Mauricio 
Published: July 2016

AbstractWe present the results of optical and near–IR spectroscopy of the massive young star associated with the extended reflection nebula Gy 2-18 (HHL31). The optical spectrum between 4000-5000 Å suggests a B0-B2 classification for this object. In addition the Hα line profile indicate the presence of a consistent stellar wind with a velocity of the order of 1200 km/s. The near-IR spectrum is dominated by the presence of the hydrogen recombination emission lines (Pfund and Bracket series). The measured line intensities of these lines are in agreement with the presence of a strong stellar wind in Gy2-18.
Be Stars in Roche-Lobe Interacting Binaries
Authors: Tarasov A.E. 
Published: July 2016

AbstractDifferent types of massive interacting binaries with Be components are discussed. Due to mass exchange, Be stars in these systems have some peculiar characteristics. Often it is even difficult to find traces of the Be star and/or mass-losing star in the optical region of the spectrum. Using the value of the orbital period as a primary parameter, it is possible to divide all massive interacting binaries into two large groups: short-period or classical Algols and long-period binaries. The last group includes a number of very active mass transfer systems named as W Serpentis. There is also a small group of double systems whose stars do not fill their Roche lobes but have emission lines in the spectrum. Properties of their spectral variability are discussed. Analysis of each group lets us find different behaviours in mass exchange that depend on the size of their Roche lobes.
Evidence for Magnetic Field Decay in the Slowest Known Be/X-ray Pulsars X Per and RX J0146.9+5121
Authors: Li X.-D. , Wang Z.-R. 
Published: July 2016

AbstractWe argue that the slowest known Be/X-ray pulsars X Per and RX J0146.9+5121 currently possess relatively weak (≲ 1012 G) magnetic fields. Unless these pulsars were born rotating very slowly (initial periods longer than tens of seconds), in order to explain their long spin periods (~ 835 and ~ 1412 s, respectively), they must have had magnetic fields stronger than a few 1013 G; that is, their magnetic fields must have decayed.
Discovery of Eight Recycled Pulsars – The Swinburne Intermediate Latitude Pulsar Survey
Authors: Edwards Russell T. 
Published: July 2016

AbstractWe have conducted a pulsar survey of intermediate Galactic latitudes (5° &lt; |b| &lt; 15°) at 20 cm. The survey has been highly successful, discovering 58 new pulsars, eight of which are recycled, in only ∼14 days of integration time. One pulsar has a very narrow (2° FWHM) average profile for the pulsar’s period (278 ms). The six new recycled binary systems provide valuable information on the formation of white dwarf pulsar binaries. Two systems have massive white dwarf companions (&gt; 0.57 M⊙and &gt; 1.2 M⊙), while another has a low mass (∼ 0.2 M⊙) companion in a 23.3-d orbit, residing the well-known orbital period “gap”.
Timing the Parkes Multibeam Pulsars
Authors: Manchester R. N. , Lyne A. G. , Camilo F. , Kaspi V. M. , Stairs I. H. , Crawford F. , Morris D. J. , Bell J. F. , D’Amico N. 
Published: July 2016

AbstractMeasurement of accurate positions, pulse periods and period derivatives is an essential follow-up to any pulsar survey. The procedures being used to obtain timing parameters for the pulsars discovered in the Parkes multibeam pulsar survey are described. Completed solutions have been obtained so far for about 80 pulsars. They show that the survey is preferentially finding pulsars with higher than average surface dipole magnetic fields. Eight pulsars have been shown to be members of binary systems and some of the more interesting results relating to these are presented.
Phase locked Spectroscopic Imaging of the Crab Pulsar
Authors: Fordham J.L.A. , Robinson J.R. , Kawakami H. , Michel R. , Much R. 
Published: July 2016

AbstractThe MIC photon counting detector developed at UCL has been upgraded to allow time resolved spectroscopic optical data to be acquired on periodical sources such as pulsars. First observing trials have been carried out on the Crab pulsar. The detector was phase locked to the pulsar period and a temporal resolution of 41.4μs employed. The phase locking allowed the co-addition of time slices over a large number of pulsar periods building up quantifiable spectroscopic data when observing in a flux limited regime.
Constraints on Emission Mechanism from the Nulling and Drifting Pulsar PSR B0031 – 07
Authors: Joshi B. C. , Vivekanand M. 
Published: July 2016

AbstractHigh sensitivity data were obtained on PSR B0031-07 using Ooty Radio Telescope (ORT), which has a single polarization. As this pulsar lies outside the range of other sensitive instruments, such observations are possible only with ORT. Some earlier results, such as the different drift modes, were verified. Our analysis suggests competition between the energies of pairs of drifting sub-pulses and a phase memory across short nulls. The constraints these results put on the theories of pulse emission are enumerated.
Hollow Core?
Authors: Qiao G.J. , Liu J.F. , Wang Yang , Wu X.J. , Han J.L. 
Published: July 2016

AbstractWe carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could beβ&lt; 0.5°. The “hollow core” is in agreement with Inverse Compton Scattering model of radio pulsars.
A Search for Variable Interstellar Magnetic Fields and Neutron Star Precession in Four Years of Polarization Position Angle Measurements on 98 Pulsars
Authors: Weisberg J. M. , Morgan J. J. , Despotes J. T. , Everett J. E. , Cordes J. M. 
Published: July 2016

AbstractWe have studied the temporal behavior of linearly polarized position angle in a sample of 98 pulsars observed from Arecibo over a four–year period in a search for free precession and changes in interstellar magnetic fields along pulsar– earth lines of sight. We set upper limits on changes in position angle.
Pulsar optical observation with the Very Large Telescope
Authors: Ray A. , Lundqvist P. , Sollerman J. , Leibundgut B. , Sutaria F. 
Published: July 2016

AbstractOptical data in the V-band gathered with the 8.2m ESO Very Large Telescope (VLT) at the radio interferometric position of PSR 1706-44 are presented. The pulsar is close to a bright star in projection and was not detected. The pulsar magnitude limit must be fainter than V=24.5 for a distance of ≤from the bright star. In the outer gap model for an aligned rotor the optical flux should scale with the gammaray flux. For pulsars which emit pulsed gamma-rays but are not detected in the optical bands, the synchrotron cutoff frequency for the tertiary photons must be well below the optical frequencies and the magnetic and spin axes may be misaligned.
Intensive X-ray Monitoring of the 16ms Crab-like Pulsar PSR J0537 – 6910
Authors: Marshall F. E. , Gotthelf E. V. , Middleditch J. , Wang Q. D. , Zhang W. 
Published: July 2016

AbstractThe recently discovered pulsar PSR J0537-6910 is the most rapidly rotating young pulsar known. This latest example of a Crab-like pulsar, located in the supernova remnant N157B in the Large Magellanic Cloud, is rotating twice as fast as the Crab pulsar. With a characteristic age of 5000 years, it is also the oldest known example of a Crab-like pulsar and was likely rotating close to the maximum rate for a neutron star when it was born. Here we report preliminary results from an intensive monitoring campaign of X-ray observations acquired with the Rossi X-ray Timing Explorer that began in January 1999. These observation have revealed a large glitch event in the pulse timing during the first six month of our campaign, consistent with those suggested by sparse observations dating back to 1993. The current evolution of the rotation rate of PSR J0537-6910 provides a unique probe of the internal structure of neutron stars and constraints on possible pulsar emission mechanisms.
Non-Dipolar Magnetic Fields in Pulsars
Authors: Eilek Jean A. , Hankins Timothy H. 
Published: July 2016

AbstractSeveral bright pulsars have position angle sweeps which are not consistent with a simple dipole field in the radio emission region. The data are now good enough to justify modelling of deviations in the field structure in these stars, and the effect of these deviations on the radio emission. As a first step, we consider the effect of quadrupoles, and of polar currents, on the observed polarization and emission signatures.
Thermal X-Ray Pulses Resulting From Pulsar Glitches
Authors: Tang Anisia P.S. , Cheng K.S. 
Published: July 2016

AbstractThe non-spherical symmetric and exact thermal evolution model is used to calculate the transient thermal response to pulsar glitches. The three ways of energy release originated from glitches, namely the ‘shell’, ‘ring’ and ‘spot’ cases are compared. The ‘ring’ case is always the middle one in terms of the response time, the response duration and the intensity of the response. Taking the relativistic light bending effect and the rotational effect into consideration, the X-ray light curves resulting from the thermal response to the glitches are calculated. Only the ‘spot’ case produces modulative X-rays. Different sets of parameters result in different evolution patterns of light curves. This is thus a good method to determine the equations of state for pulsars.
The Pair Cascade in Strong and Weak Field Pulsars
Authors: Arendt, Paul N. , Eilek Jean A. 
Published: July 2016

AbstractWe have simulated the development of the pair cascade in a range of magnetic field strengths. We determined the efficiencies of lepton and secondary photon production, as well as the distribution functions of the pair plasma and of the escaping photons. We find the magnetic field has the most important effect on the cascade; primary beam energies and seed photon emissivities are of less importance.
Puzzling Pulsars and Supernova Remnants
Authors: Lorimer D.R. , Ramachandran R. 
Published: July 2016

AbstractThe fact that the majority of the youngest radio pulsars are surrounded by expanding supernova remnants is strong evidence that neutron stars are produced in the supernovae of massive stars. In many cases, the pulsar appears significantly offset from the geometric centre of the supernova remnant, indicating that the neutron star has moved away from the site of the explosion with a substantial space velocity since birth. Here we show that the these offsets show an overwhelming preference for one sign in terms of Galactic longitude, a result that has important implications for the number of genuine associations. The origin of this statistically significant effect may lie in a differential Galactic rotational velocity between stars and gas in the interstellar medium.
Time-variability of the Crab Nebula wisps
Authors: Spitkovsky Anatoly , Arons Jonathan 
Published: July 2016

AbstractWe present results of time-dependent numerical modeling of the internal structure of the collisionless shock terminating the pulsar wind in Crab Nebula. We treat the equatorial relativistic wind as composed of ions and electron-positron plasma with an embedded toroidal magnetic field. Relativistic cyclotron instability of the ion ring downstream from the shock is found to launch outward propagating magnetosonic waves. Due to the fresh supply of ions crossing the shock, the time-dependent process achieves a limit-cycle pattern, in which the waves are launched with periodicity on the order of the ion Larmor time. Compressions in magnetic field and pair density associated with these waves as well as their propagation speed qualitatively reproduce the features observed in the wisps.
The interaction of pulsar winds with old supernova remnants
Authors: van der Swaluw Eric , Achterberg Abraham , Gallant Yves A. 
Published: July 2016

Shock waves in young supernova remnants (SNR) are generally considered to be the places where production and acceleration of charged particles (relativistic electrons and cosmic rays) take place. Older remnants can be re-energised if an active pulsar catches up with the shell of the remnant (Shull, Fesen, &amp; Saken 1989). In that case a pulsar-driven wind can inject energetic particles into the shell, resulting into a rejuvenation of the radio emission of the old remnant due to the presence of additional relativistic electrons.Radio observations of CTB80 (Angerhofer et al. 1981) and G5.4-1.2 (Frail &amp; Kulkarni 1991) give evidence for the importance of the presence of an active pulsar close to the old shell of the remnants. In the first case the pulsar is believed to be inside the SNR. In the second case the pulsar is thought to have penetrated the shell of the SNR, and resides in the interstellar medium (ISM). We intend to investigate the physics which are connected with these kind of systems. One expects new effects resulting from the interaction of the three different shocks; the SNR shock, the bowshock bounding the pulsar wind nebula (PWN) and the (pulsar) wind termination shock. The dynamics of the system is described by a hydrodynamics code. We use the results from the hydrodynamics code to investigate the process of acceleration and transport of particles which are advected by the flow and diffuse with respect to the flow. We have applied the latter to a simple problem, the case of a spherically expanding SNR.
The Remarkable Binary Pulsar PSR B1259–63
Authors: Johnston Simon 
Published: July 2016

AbstractPSR B1259–63 is a unique system consisting of a young radio pulsar in orbit about a 10 M⊙Be star. Its orbital period is 3.4 yr and the eccentricity close to 0.9. Around periastron, the system is a radio and X-ray transient and shows changes in flux density, dispersion measure, rotation measure and scattering parameters on very short timescales. Timing observations show the equatorial plane of the Be star and the plane of the orbit are not aligned and the orbit precesses as a result. I briefly summarise 10 years of radio observations of PSR B1259–63 and the implications of these observations. Future work includes the determination of the orbital size through VLBI and observations at TeV energies.