bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Virgo High-Resolution CO Survey: III. NGC 4254
Authors: Sofue Yoshiaki , Koda Jin , Nakanishi Hiroyuki , Hidaka Makoto 
Published: March 2014

Abstract
We present high-angular-resolution (${1\rlap {.}{}^{\mathrm {\prime \prime }}5}$-${5{}^{\mathrm {\prime \prime }}}$) interferometer observations of the ${{12\atop} \mathrm{CO}}$ ($J=1 \hbox{--} 0$) line emission in the central region of the SA(s)c galaxy NGC 4254 (M 99). The observations were obtained using the Nobeyama Millimeter-wave Array (NMA) during the course of a long-term CO-line survey of Virgo spirals. We present the spectra, channel maps, integrated intensity distributions, velocity fields, position–velocity diagrams, and compare the data with various optical images. The rotation velocity is already finite at the nucleus, or at least it rises steeply to $80 \,\mathrm{km} \,\mathrm{s}^{-1}$ within the central $1^{\prime\prime}$, indicating the existence of a massive core of $10^8 \,{{{M}_{\odot}}}$ within $1^{\prime\prime}$ (80 pc) radius. The CO intensity maps show that the inner disk has well-developed multiple spiral arms, winding out from a bar-shaped elongated molecular complex. In addition to the bisymmetric spiral arms, an asymmetric tightly wound arm with high molecular gas density is found to wind out from the molecular bar. The molecular spiral arms, particularly the tightly wound arm, well traces optical dark lanes, and are associated with $\mathrm{H}\alpha$ arms having many H ii regions. The inner asymmetric spiral structures can be explained by ram-pressure distortion of inter-arm low density regions of the inner disk by the intra-cluster gas wind, and is indeed reproduced by a hydrodynamical simulation.
Enhanced HCN (1-0) Emission in the Type-1 Seyfert Galaxy NGC 1097
Authors: Kohno Kotaro , Ishizuki Sumio , Matsushita Satoki , Vila-Vilaró Baltasar , Kawabe Ryohei 
Published: March 2014

Abstract
The central kpc region of the low-luminosity type-1 Seyfert galaxy NGC 1097 has been observed in the CO (1–0) and HCN (1–0) lines with the Nobeyama Millimeter Array and the NRO 45 m telescope. We have found a striking enhancement of the HCN emission toward the active nucleus of NGC 1097; a large fraction of the CO emission comes from a circumnuclear starburst ring ($r \sim 10''$ or 700 pc at $D = 14.5 \,\mathrm{Mpc}$), whereas the HCN emission is dominated by a strong unresolved peak at the nucleus. The HCN-to-CO integrated intensity ratio on the brightness temperature scale, $R_\mathrm{HCN/CO}$, is about 0.11 in the aperture of the 45 m telescope beams (${15{}^{\mathrm {\prime \prime }}}$ for CO and ${19{}^{\mathrm {\prime \prime }}}$ for HCN), but reaches 0.34 in the smaller aperture (${10{}^{\mathrm {\prime \prime }}} \times {4\rlap {.}{}^{\mathrm {\prime \prime }}4}$). These CO and HCN properties in NGC 1097 are similar to those in the type-2 Seyfert galaxies NGC 1068 and NGC 5194 (M 51).
Wavy Stratus under Photon Surfing over Luminous Disks
Authors: Fukue Jun 
Published: March 2014

Abstract
In a geometrically thin cloud layer under photon surfing over an infinite disk with uniform brightness, a wavy fluctuation automatically amplifies itself. This is a new type of instability for an inhomogeneous stratus moving at a relativistic speed in intense radiation fields. Under radiative flux and drag forces, the equilibrium speed of a wave top can reach ultra-relativistic speed, although the equilibrium speed of a wave base remains in the mildly relativistic regime ($\sim 0.45 \,c$) due to radiation drag. That is, the equilibrium speed of the wavy stratus with wavelength $\lambda$ becomes $0.99 \,c$ (Lorentz factor $\gamma \sim 10$) at height $z \sim 10 \,\lambda$. As a result, the radiation-drag limit in the astrophysical jets can be broken. The terminal speed, which depends on the strength of radiation fields as well as the wavelength, is also obtained.
Non-Linear Resonance in Nearly Geodesic Motion in Low-Mass X-Ray Binaries
Authors: Abramowicz Marek A. , Karas Vladimir , Kluźniak Wodzimierz , Lee William H. , Rebusco Paola 
Published: March 2014

Abstract
We have explored the ideas that parametric resonance affects nearly geodesic motion around a black hole or a neutron star, and that it may be relevant to the high-frequency (twin) quasi-periodic oscillations that occur in some low-mass X-ray binaries. We have assumed the particles or fluid elements of an accretion disc to be subject to an isotropic perturbation having a hypothetical but rather general form. We find that the parametric resonance is indeed excited close to the radius where epicyclic frequencies of the radial and meridional oscillations are in a $2:3$ ratio. The location and frequencies of the highest amplitude excitation vary with the strength of the perturbation. These results agree with actual frequency ratios of twin kHz QPOs that have been reported in some black hole candidates, and they may be consistent also with correlation of the twin peaks in Sco X-1.
X-Ray and Gamma-Ray Emissions from the PSR 1259$-$63/Be Star System
Authors: Murata Kenji , Tamaki Hidenori , Maki Hideki , Shibazaki Noriaki 
Published: March 2014

Abstract
PSR1259$-$63 is a radio pulsar orbiting a Be star in a highly eccentric orbit. Soft and hard X-rays are observed from this binary system. We applied a shock-powered emission model to this system. The collision of the pulsar and Be star winds forms a shock, which accelerates electrons and positrons to relativistic energies. We derived the energy distribution of relativistic electrons and positrons as a function of the distance from the shock in the pulsar nebula. We calculated the X-rays and $\gamma$-rays emitted from the relativistic electrons and positrons in the nebula at various orbital phases, while fully taking into account the Klein–Nishina effect. The shock-powered emission model can explain the observed X-ray properties approximately. We obtained from comparisons with observations that a fraction of $\sim 0.1$ of the pulsar spin-down luminosity should be transformed into the relativistic electrons and positrons. We found that the magnetization parameter of the pulsar wind, the ratio of the Poynting flux to the kinetic energy flux, is $\sim 0.1$ immediately upstream of the termination shock of the pulsar wind, and may decrease with the distance from the pulsar. We predict a flux of 10 MeV–100 GeV $\gamma$–rays, which may be nearly equal to the detection threshold in the future projects.
The SU UMa Nature of the Dwarf Nova, DM Lyrae
Authors: Nogami Daisaku , Baba Hajime , Matsumoto Katsura , Kato Taichi 
Published: March 2014

Abstract
We carried out time-resolved $V$-band photometry of DM Lyr during long outbursts in 1996 July and in 1996 February–March at Ouda Station, Kyoto University, and at Osaka Kyoiku University. Since superhumps were clearly detected in the light curves, DM Lyr was first identified as being an SU UMa-type dwarf nova. The superhump period is 0.0673(2) d, and the superhump excess is 2.8(3)%. The duration of the superoutburst, the outburst amplitude, the decline rate in the plateau phase, and the superhump excess were typical values for a usual SU UMa star. According to visual and CCD observations reported to VSNET, this star has experienced a dramatic change of the outburst pattern from a superoutburst phase to a normal outburst phase. There may exist mechanisms to decrease the number of normal outbursts between two successive superoutbursts and to elongate the recurrence cycle of the superoutburst.
Grazing Eclipsing Dwarf Nova CW Monocerotis: Dwarf Nova-Type Outburst in a Possible Intermediate Polar?
Authors: Kato Taichi , Uemura Makoto , Kiyota Seiichiro , Tanabe Kenji , Koizumi Mitsuo , Kida Mayumi , Nishi Yuichi , Tanaka Sawa , Ueoka Rie , Yasui Hideki , Vanmunster Tonny , Nogami Daisaku , Yamaoka Hitoshi 
Published: March 2014

Abstract
We observed the 2002 October–November outburst of the dwarf nova CW Mon. The outburst showed a clear signature of a premaximum halt, and a more rapid decline after reaching the outburst maximum. On two separate occasions, during the premaximum stage and near the outburst maximum, shallow eclipses were recorded. This finding confirms the previously suggested possibility of the grazing eclipsing nature of this system. The separate occurrence of the eclipses and the premaximum halt can be understood as being the result of a combination of a two-step ignition of an outburst and the inside-out propagation of the heating wave. We detected a coherent short-period (0.02549 d) signal on two subsequent nights around the optical maximum. This signal was likely present during the maximum phase of the 2000 January outburst. We interpret this signal as being a signature of the intermediate polar (IP) type pulses. The rather strange outburst properties, strong and hard X-ray emission, and the low luminosity of the outburst maximum might be understood as a consequence of the supposed IP nature. The ratio between the suggested spin period and the orbital period, however, is rather unusual for a system having an orbital period of $\sim 0.176 \,\mathrm{d}$.
Fading of Sunlight Scattered by a Meteoric Cloud of the Leonid Parent Comet 55P/Tempel-Tuttle
Authors: Usui Fumihiko , Ishiguro Masateru 
Published: March 2014

Abstract
During the Leonid meteor shower in 1998, a faint glow in the direction of the dust trail of comet 55P/Tempel-Tuttle was discovered using photometric observations (Nakamura et al. 2000, ApJ, 540, 1172). It is considered that this glow was due to sunlight scattered by sub-millimeter-sized dust particles located along the orbit of 55P/Tempel-Tuttle. To examine the spatial distribution of the dust particles, we observed the sky in the direction of the dust trail on 2001 November 18, but the data taken at this epoch showed no significant evidence of scattered sunlight. Based on data obtained at both epochs of observation, 1998 and 2001, we discuss two possible scenarios for the fading of the meteoric cloud: sublimation of volatiles in the dust grains, and/or an expansion of the width of the trail. If the latter scenario is correct, the trail at the time of the 2001 observations would have been four-times wider than in 1998.
High-Precision Radiant Analysis of the 2001 Leonids Using Telescopic Optics
Authors: Yanagisawa Toshifumi , Ohnishi Kouji , Torii Ken’ichi , Kohama Mitsuhiro , Nakajima Atsushi , Asher David 
Published: March 2014

Abstract
We employed a new line-detection method and tried to separate two radiant points corresponding to the dust trails of Comet 55P/Tempel–Tuttle’s perihelion passages in 1699 and 1866. This method integrates the pixel values of a CCD image along a line direction, which enables us to detect 30-times fainter meteors than when using the usual detection methods. It can also precisely determine the angle of the line direction. Two telescopic optics equipped with cooled CCD cameras were pointed to regions that make a right angle with the radiant points in order to precisely determine their positions. Radiant points of the 2001 Leonids derived by this method were found to be consistent with those predicted by McNaught and Asher.
Wide-Field Video Observation and Statistical Analysis of the Leonid Meteor Storm in 2001
Authors: Shiki Shigetomo , Fujiwara Hideaki , Kitazume Jun , Miyamoto Daisuke , Takeuchi Tsutomu T. , Utsumi Yousuke 
Published: March 2014

Abstract
We show a detailed analysis of a wide-field video observation of the Leonid Meteor Storm from ${14{}^{\mathrm {h}}41{}^{\mathrm {m}}}$ through ${20{}^{\mathrm {h}}03{}^{\mathrm {m}}}$ (UT) on 2001 November 18. We detected 1573 meteors of Leonids and 64 meteors of others. The peak of the storm appeared at ${18{}^{\mathrm {h}}20{}^{\mathrm {m}}}$ and its duration was 1.9 hr (FWHM). Bright ($m\leq2.5$) and faint ($m \geq 2.5$) meteors showed significantly different behavior in their activity. Especially, after ${19{}^{\mathrm {h}}15{}^{\mathrm {m}}}$, bright objects dominated the meteor events. We found many local peaks in the count record, and most of local peaks consisted of faint meteors. The autocorrelation function and the interval distribution between the meteor arrivals suggest that the distribution of dust in the cometary trails has no significant spatial structures that give rise to a temporally coherent behavior with a time-scale of seconds to minutes.
Dispersion of the Break Energy in the GRB Internal Shock Model
Authors: Asano Katsuaki , Kobayashi Shiho 
Published: March 2014

Abstract
In order to investigate the dispersion of the spectral break energy in gamma-ray bursts, we simulate internal shocks, including effects of shell-splitting after shell collisions and the Thomson optical depth due to electron–positron pairs produced by synchrotron photons. We produce pseudo-observational data and estimate the break energy. If the distribution of initial Lorentz factors of shells has only one peak, many pulses with a break energy much lower than the typical observed value should be detected, while the effect of the Thomson optical depth reduces pulses with a break energy of $ \gt 1 \,\mathrm{MeV}$$ \gt 1 \,\mathrm{MeV}$. If the Lorentz factor distribution has multiple peaks, the distribution of the break energy can be consistent with observations.
Detection of Molecular Clouds in the Interarm of the Flocculent Galaxy NGC 5055
Authors: Tosaki Tomoka , Shioya Yasuhiro , Kuno Nario , Nakanishi Kouichiro , Hasegawa Takashi 
Published: March 2014

Abstract
We present high-resolution ($\sim {4{}^{\mathrm {\prime \prime }}}$)${{12\atop} \mathrm{CO}}$ ($J = 1 \hbox{--} 0$) mapping observations with high-velocity resolution (${\sim 2.6 \,\mathrm{km} \,\mathrm{s}^{-1}}$) toward the disk of flocculent galaxy NGC 5055, using the Nobeyama Millimeter Array in order to study the physical properties of the molecular clouds in the arm and the interarm. The map shows clumpy structures. Although these are mainly distributed along an arm seen in NIR, some are located in the interarm. These clouds in the arm and the interarm have a typical size and mass of a few 100 pc and a few $10^6 \,{{{M}_{\odot}}}$. These correspond to the largest Giant Molecular Cloud (GMC) in our Galaxy, and are slightly smaller than Giant Molecular Associations (GMAs) in the grand design spiral M 51. Their CO flux-based masses show good agreement with their virial masses. A size–velocity dispersion relation is plotted on an extension of the relation for the Galactic GMCs. It suggest that the properties of these clouds are similar to that of the Galactic GMCs. We found no clear systematic offset between the molecular gas and H ii regions unlike M 51. This and no existense of GMAs suggest that, in NGC 5055, cloud formation and star formation in the arm and the interarm are due to enhancement of gas by local fluctuation; while, in grand design spiral galaxies, such as M 51, GMA formations may occur only in the arm due to a strong density wave and enhanced star formation in GMA formation may occur. These may control the optical morphology of spiral arms in spiral galaxies.
An X-Ray Detection Possibility of Star-Formation-Bursting Proto-Elliptical Galaxies
Authors: Inoue Hajime , Yamasaki Noriko Y. 
Published: March 2014

Abstract
A possibility to detect X-rays from star-formation burst activities in proto-elliptical galaxies is considered. The X-ray flux of an emission due to inverse-Compton scattering of the cosmic microwave background (CMB) by high energy electrons accelerated in SNRs is shown to increase as $z$ increases far beyond unity, since the local CMB flux largely increases in association with a $z$-increase. The flux is estimated for the case of a very high rate of type II supernovae at an initial star formation burst of a proto-elliptical galaxy and is found to be detectable with a future large X-ray telescope such as intended in the XEUS mission.
Size and Spatial Distributions of Sub-km Main-Belt Asteroids
Authors: Yoshida Fumi , Nakamura Tsuko , Watanabe Jun-ichi , Kinoshita Daisuke , Yamamoto Naotaka , Fuse Tetsuharu 
Published: March 2014

Abstract
This paper presents the result of the first systematic investigation of very small Main-Belt Asteroids (sub-km MBAs) using the Subaru Prime-Focus Camera (Suprime-Cam) with an $8 \,\mathrm{K} \times 10 \,\mathrm{K}$ mosaic CCD array attached to the 8.2m Subaru Telescope atop Mauna Kea, Hawaii. We call this survey SMBAS (Sub-km Main-Belt Asteroid Survey). Observations were carried out on 2001 February 22 and 25 (HST) and a $\sim 3.0 \,\mathrm{deg}^{2}$ sky area near the opposition and near the ecliptic was searched. We detected 1111 moving objects down to $R \sim 26 \,\mathrm{mag}$ (including very slow Trans-Neptunian Objects). In this survey, we could not determine the exact orbits of the moving objects, because of their short observational arc of only 2 hours. Instead, we statistically estimated the semi-major axis ($a$) and inclination ($I$) of each moving object from its apparent sky-motion vector, and then obtained the size and spatial distributions of sub-km MBAs. The main results of SMBAS are: (1) The sky number density of MBAs is found to be $\sim 290 \,\mathrm{deg}^{-2}$ down to $R\sim 24.4 \,\mathrm{mag}$ (for MBAs) near the opposition and near the ecliptic. (2) The slope of the cumulative size distribution for sub-km MBAs ranging from 0.5 km to 1 km in diameter is fairly shallower ($\sim 1.2$) than that for large MBAs of more than $\sim 5 \,\mathrm{km}$ in diameter ($\sim 1.8$), which was obtained from past asteroid surveys. This means that the number of sub-km MBAs is much more depleted than a result extrapolated from the size distributions for large asteroids. (3) The depletion of sub-km MBAs is clearer in the outer main-belt than in the inner main-belt. (4) It seems that SMBAS asteroids distribute more widely in the $I$-direction in the outer zone ($a= 2.8 \hbox{--} 3.1 \,\mathrm{AU}$) of the main-belt than known large asteroids do. We also discuss the possible causes for the characteristics of the distributions of SMBAS-observed small asteroids.
Slow and Fast MHD Shocks Associated with a Giant Cusp-Shaped Arcade on 1992 January 24
Authors: Shiota Daikou , Yamamoto Tetsuya T. , Sakajiri Takuma , Isobe Hiroaki , Chen Peng-Fei , Shibata Kazunari 
Published: March 2014

Abstract
We performed magnetohydrodynamic (MHD) simulations of a giant arcade formation with a model of magnetic reconnection coupled with heat conduction, to investigate the dynamical structure of slow and fast MHD shocks associated with reconnection. Based on the numerical results, theoretical soft X-ray images were calculated and compared with the Yohkoh soft X-ray observations of a giant arcade on 1992 January 24. The Y-shaped structure observed in the event was identified to correspond to the slow and fast shocks associated with the magnetic reconnection.
Probing the Star-Formation Epoch with the Wilkinson Microwave Anisotropy Probe (WMAP) Data and High-Redshift QSOs
Authors: Yokoyama Jun’Ichi 
Published: March 2014

Abstract
Using the values of the cosmological parameters obtained from the Wilkinson Microwave Anisotropy Probe (WMAP) and the cosmological chemical clock observed from high-redshift quasars, it is shown that the formation epoch of precursors of type Ia supernovae should have started at a redshift of $z_{\mathrm{F}} \gt 9.5$$z_{\mathrm{F}} \gt 9.5$, and that $z_\mathrm{F}$ is sensitive only to $\Omega_{\mathrm{m0}} \, h^2$ in flat $\Lambda$CDM cosmology.
Dusty ERO Search behind Two Massive Clusters
Authors: Takata Tadafumi , Kashikawa Nobunari , Nakanishi Kouichiro , Aoki Kentaro , Asai Ryo , Ebizuka Noboru , Inata Motoko , Iye Masanori , Kawabata Koji S. , Kosugi George , Ohyama Youichi , Okita Kiichi , Sasaki Toshiyuki , Saito Yoshihiko , Sekiguchi Kazuhiro , Shimizu Yasuhiro , Taguchi Hiroko , Yoshida Michitoshi 
Published: March 2014

Abstract
We performed deep $K'$-band imaging observations of 2 massive clusters, MS 0451.6$-$0305 at $z = 0.55$ and MS 0440.5$+$0204 at $z = 0.19$, for searching counterparts of the faint sub-mm sources behind these clusters, which would provide one of the deepest extremely red object (ERO) samples. Comparing our near-infrared images with optical images taken by the Hubble Space Telescope and by the Subaru Telescope, we identified 13 EROs in these fields. The sky distributions of EROs are consistent with the previous results, that there is a sign of strong clustering among detected EROs. Also, the surface density with corrected lensing amplification factors in both clusters are in good agreement with that derived from previous surveys. We found 7 EROs and 3 additional very red objects in a small area ($\sim 0.6 \,\mathrm{arcmin}^{2}$) of the MS 0451.6$-$0305 field around an extended SCUBA source. Many of their optical and near-infrared colors are consistent with dusty star-forming galaxies at high redshifts ($z \sim 1.0 \hbox{--} 4.0$), and they may be constituting a cluster of dusty starburst galaxies and/or lensed star-forming galaxies at high redshift. Their red $J-K'$ colors and faint optical magnitudes suggest they are relatively old massive stellar systems with ages ($ \gt 300$ mega years) suffering from dust obscuration. We also found a surface-density enhancement of EROs around the SCUBA source in the MS 0440.5$+$0204 field.
Helical Tomography of an Accretion Disk by Superhump Light Curves of the 2001 Outburst of WZ Sagittae
Authors: Osaki Yoji 
Published: March 2014

Abstract
A new method for analyzing complex superhump light curves for the 2001 outburst of WZ Sagittae is proposed. The complexity arises because intrinsically time-varying and non-axisymmetric distributions of superhump light sources are coupled with the aspect effects around the binary orbital phase because of its high orbital inclination. The new method can disentangle these complexities by separating the non-axisymmetric spatial distribution in the disk from the time variation with the superhump period. It may be called a helical tomography of an accretion disk because it can reconstruct a series of disk images (i.e., disk’s azimuthal structures) at different superhump phases. The power spectral data of superhump light curves of the 2001 outburst of WZ Sge by Patterson et al. (2002, PASP, 114, 721) are now interpreted under a new light based on the concept of helical tomography, and the azimuthal wave numbers of various frequency modes are identified. In particular, a frequency component, $n\omega_0-\Omega$, where $\omega_0$ and $\Omega$ are the orbital frequency and a low frequency of the apsidal precession of the eccentric disk, is understood as an $(n-1)$-armed traveling wave in the disk. A vigorous excitation of a wave component of $\cos(2\Theta-3\omega_0 t)$ in the first week of the superhump era of WZ Sge, where $\Theta$ is the azimuthal angle, supports Lubow’s (1991, AAA 54.064.175) theory of non-linear wave coupling of the eccentric Lindblad resonance for the superhump phenomenon. This method can in principle be applied to other SU UMa stars with high orbital inclination if light curves are fully covered over the beat cycle.