bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of Cluster Galaxies in Hierarchical Clustering Universes
Authors: Okamoto Takashi , Habe Asao
Published: March 2014

Using cosmological N-body simulations of critical (SCDM) and open (Ω = 0.3, OCDM) cold dark matter models, we investigated the evolution of cluster galaxies. Based on our numerical simulation, we constructed merging history trees of the galaxies. By following their merging history, we could show that the major merger fractions of the galaxies in cluster-forming regions is roughly proportional to (1+z)4.5 at low redshifts (z < 2), and has a steep peak at z ≃ 2.5 and z ≃ 3 in SCDM and OCDM, respectively. We also show that the cluster galaxies are affected by the tidal interaction after the clusters are formed. Because the formation redshift of the cluster in SCDM, zform = 0.15, is much more recent than that of the cluster in OCDM, zform = 1.6, the cluster galaxies in SCDM show more rapid evolution by tidal interactions from z = 0.5 than those in OCDM.
Magnetic Field Evolution Leading to Solar Flares II. Cases with High Magnetic Shear and Flare-Related Shear Change
Authors: Li Hui , Sakurai Takashi , Ichimoto Kiyoshi , UeNo Satoru
Published: March 2014

Following Paper I in which we considered five solar flares, we have selected another three solar flares greater than GOES X-ray class M/Hα importance 1. The three active regions discussed here are characterized by high magnetic shear. We investigated the spatial relationships among Hα flare ribbons, soft X-ray (SXR) flare loops, and magnetic configurations for the three flares produced in these active regions. Our results show that only one of these three flares satisfies the sufficient conditions for a flare to occur proposed by Hagyard (1990, AAA 052.075.047). We also discuss the magnetic shear changes around the flaring time only along the neutral lines associated with the studied flares and over the whole flaring area. The flare-related changes on the neutral line are small (2°–4°) and the association of these changes with the flares is not conclusive. The average shear in the flaring areas of the flares associated with high shear decreases significantly after the flares and it may be a better parameter to characterize the flare-related shear changes in such cases.
Conversion Law of Infrared Luminosity to Star-Formation Rate for Galaxies
Authors: Inoue Akio K. , Hirashita Hiroyuki , Kamaya Hideyuki
Published: March 2014

We construct a new algorithm for estimating the star-formation rate (SFR) of galaxies from their infrared (IR) luminosity by developing the theory of the IR emission from a dusty H II region. The derived formula is SFR $/(M_\odot \textrm {yr}^{-1})= [3.3 \times 10^{-10}(1- \eta)/(0.4-0.2f+0.6 \epsilon)](L^{obs}_{IR}/L_\odot)$, where f is the fraction of ionizing photons absorbed by hydrogen, ε is the efficiency of dust absorption for nonionizing photons from OB stars, and η is the cirrus fraction of observed IR luminosity. The previous conversion formulae of SFR from the IR luminosity are applicable to only the case where the observed IR luminosity is nearly equal to the bolometric luminosity (starburst galaxies etc.), except for some empirical formulae. On the other hand, our theoretical SFR is applicable to galaxies even with a moderate star-formation activity. That is, our simple and convenient formula is significantly useful for estimating the SFR of various morphologies and types of galaxies – from early elliptical to late spiral and irregular galaxies, or from active starburst to quiescent galaxies – as long as they have neither an abnormal dust-to-gas ratio nor an evident active galactic nucleus.
Subaru Infrared Spectroscopy of the Pluto–Charon System
Authors: Nakamura Ryosuke , Sumikawa Shinji , Ishiguro Masateru , Mukai Tadashi , Iwamuro Fumihide , Terada Hiroshi , Motohara Kentaro , Goto Miwa , Hata Ryuji , Taguchi Tomoyuki , Harashima Takashi , Kaifu Norio , Hayashi Masahiko , Maihara Toshinori
Published: March 2014

We present the results of the near-infrared spectroscopy of the Pluto-Charon system, conducted in the K band at two different sub-Earth longitudes. The spatially resolved images resulted in separated spectra with a spectral resolution of approximately 530. The spectrum of Charon showed a broad absorption feature at 2 μm during both orbital phases, suggesting a uniform distribution of water ice. In the separated spectrum of Pluto obtained in June, we confirmed the absorption bands of solid methane, carbon monoxide, and nitrogen ices. Additional weak dips have been found at 2.28, 2.32, and 2.40 μm in the spectrum of the opposite side observed in May. In order to examine the carrier of these dips, we performed model calculations of the reflectance of Pluto using Hapke's bidirectional reflectance model for icy intimate mixtures. By adding a small amount of solid ethane into the mixture, we successfully reproduced the dips at 2.28 and 2.315 μm, but the absorption at 2.40 μm is more distinct than that in the observed spectrum.
J-Net Galactic-Plane Survey of VLBI Radio Sources for VLBI Exploration of Radio Astrometry (VERA)
Authors: Honma Mareki , Oyama Tomoaki , Hachisuka Kazuya , Sawada-Satoh Satoko , Sebata Kouichi , Miyoshi Makoto , Kameya Osamu , Manabe Seiji , Kawaguchi Noriyuki , Sasao Tetsuo , Kameno Seiji , Fujisawa Kenta , Shibata Katsunori M. , Bushimata Takeshi , Miyaji Takeshi , Kobayashi Hideyuki , Inoue Makoto , Imai Hiroshi , Araki Hiroshi , Hanada Hideo , Iwadate Kenzaburo , Kaneko Yoshihisa , Kuji Seisuke , Sato Katsuhisa , Tsuruta Seiitsu , Sakai Satoshi , Tamura Yoshiaki , Horiai Koji , Hara Tadayoshi , Yokoyama Koichi , Nakajima Junichi , Kawai Eiji , Okubo Hiroshi , Osaki Hiro , Koyama Yasuhiro , Sekido Mamoru , Suzuyama Tomonari , Ichikawa Ryuichi , Kondo Tetsuro , Sakai Kensei , Wada Katsuhiro , Harada Naohiko , Tougou Norihiro , Fujishita Mitsumi , Shimizu Rie , Kawaguchi Satomi , Yoshimura Akane , Nakamura Masakazu , Hasegawa Wataru , Morisaki Satoshi , Kamohara Ryuichi , Funaki Tomoe , Yamashita Naoko , Watanabe Teruhiko , Shimoikura Tomomi , Nishio Masanori , Omodaka Toshihiro , Okudaira Atuya
Published: March 2014

In order to search for new VLBI sources in the galactic plane that can be used as phase reference sources in differential VLBI, we conducted 22 GHz observations of radio sources in the galactic plane using the Japanese VLBI Network (J-Net). We have observed 267 VLBI source candidates selected from existing radio surveys and have detected 93 sources at a signal-to-noise ratio larger than 5. While 42 of the 93 detected sources had already been detected with VLBI at relatively lower frequency (typically 2 to 8 GHz), the remaining 51 are found to be new VLBI sources detected for the first time. These are located within |b| ≤ 5°, and have a large number of galactic maser sources around them. Thus, they are potential candidates for phase reference sources for VLBI Exploration of Radio Astrometry (VERA), which is the first VLBI array dedicated to phase-referencing VLBI astrometry aimed at measuring the parallax and proper motion of maser sources in the whole Galaxy.
Electrodynamic Structure of an Outer-Gap Accelerator: Invisibility of the TeV Emission from a Pulsar Magnetosphere
Authors: Hirotani Kouichi
Published: March 2014

We consider the γ-ray emissions from an outer-magnetospheric gap around a rotating neutron star. Migratory electrons and positrons are accelerated by the electric field exerted in the gap to radiate copious γ -rays via a curvature process. Some of these γ-rays materialize as pairs within the gap by colliding with the X-rays, leading to a pair-production cascade. The replenished charges partially screen the original acceleration field, which is self-consistently solved from the Poisson equation for the electrostatic potential. By considering the γ-ray spectrum explicitly, we compute the pair-production rate in the gap to solve the Boltzmann equations for γ-rays, together with the continuity equations for particles and the Poisson equation. It is demonstrate that the pulsed emission above 5 TeV due to the inverse Compton scatterings could not be detected by the current ground-based telescopes for ordinary pulsar parameters.
Fragmentation of Cosmologically Collapsed Layers
Authors: Hosokawa Tamaki , Ôishi Tomohiro , Yoshida Tatsuo , Yokosawa Masayoshi
Published: March 2014

The fragmentation and dynamics of pancake-like collapsed layers are discussed. The fragmentation theory for an isothermal gas layer is extended to the case of the transverse expansion or contraction of a layer with two components. The expansion of a layer suppresses the growth of a perturbation and the contraction enhances the perturbation. It is shown that the growth rate increases exponentially with the deceleration of expansion. The critical wave number for the instability is almost constant for various rates of the expansion. The linear interaction of a perturbation between the cooled layer and a hot layer composed of dark matter changes the growth rate. The growth rate of the cooled layer is superior to the maximum value of the growth rate in isolated cases when the scale heights of both layers are not so different. This fragmentation theory is applied to cosmologically collapsed layers that were calculated by numerical simulations. The cooled layers produced by t he collapse with transverse expansion have nearly the same density and temperature over a wide scale range of primordial density fluctuations, λ = 1–20 Mpc. The mass of fragmentation is determined by evaluating the growth time of the perturbation and the accretion time of the cooled layer. The typical masses of the fragmentation are distributed over a narrow mass scale of 107–8M⊙ . A large dynamic range of the calculation, 106–8, is required to simulate the central region of the collapsed layer for the fluctuation wavelength, λ = 10 Mpc. A calculation method with extremely large dynamic range is also presented.
The Hardness-Duration Correlation in the Two Classes of Gamma-Ray Bursts
Authors: Qin Yi-Ping , Xie Guang-Zhong , Xue Sui-Jian , Liang En-Wei , Zheng Xue-Tang , Mei Dong-Cheng
Published: March 2014

The well-known hardness-duration correlation of gamma-ray bursts (GRBs) is investigated using data from the 4B catalog. We find that, while the hardness ratio and the duration are obviously correlated for the entire set of the 4B catalog, they are not at all correlated for the two subsets divided at the duration of 2 seconds. However, for other subsets with comparable sizes, the two quantities are significantly correlated. The following conclusions are thus reached: (1) the existence of two classes of GRBs is confirmed; (2) the hardness ratio and the duration are not at all correlated for any of the two classes; (3) different classes of GRBs have different distributions of the hardness ratio and the duration, and it is this difference that causes the correlation between the two quantities for the entire set of bursts.
Interstellar-Cloud Formation in the Extended Envelopes of Blue Compact Dwarf Galaxies
Authors: Saitō Mamoru , Kamaya Hideyuki , Tomita Akihiko
Published: March 2014

Blue compact dwarf galaxies (BCDs) have an interesting feature in their central region where stars are actively forming. In this paper, we show that shock waves produced by the starbursts there are able to trigger self-gravitating interstellar clouds in extended envelopes, which are often observed in typical BCDs. The criterion adopted for the formation of interstellar clouds is very simple, that is, $\rho \gt 2 \Gamma{\bar{\rho}}/3$. Here, ρ is the gas density of the shocked layer, ${\bar{\rho}}$ is a mean density including the dark matter, and Γ is a numerical factor between 0.5 and 1.0, depending on the mass distribution of the galaxy. Hence, we suggest that the infalling of the clouds onto the central regions causes subsequent starbursts after ∼ 0.1 Gyr of the event, and that the episodic starbursts continue during sub-Gyr.
Infrared Properties of SiO Maser Sources in Late-Type Stars
Authors: Matsuura Mikako , Yamamura Issei , Murakami Hiroshi , Onaka Takashi , Ootsubo Takafumi , Tohya Takanao , Okamura Yoshihiko , Freund Minoru M. , Tanaka Masahiro
Published: March 2014

The results of an SiO maser survey for late-type stars selected by the IRTS (Infrared Telescope in Space) are presented. We have detected SiO J = 1–0, v = 1 and/or v = 2 lines in 27 stars out of 59 stars. The maser intensity increases with the depth of the H2O absorption in the infrared spectra and redness of the 2.2 and 12 μm color. The column densities of the water vapor in the target stars were estimated from the depth of the water absorption in the IRTS spectra. We found that the SiO maser was detected mostly in the stars with a column density of water vapor higher than 3 × 1019–3 ×20 cm−2. We further estimated the density of hydrogen molecules in the outer atmosphere corresponding to these column densities, obtaining 109–1010 cm−3 as a lower limit. These values are roughly in agreement with the critical hydrogen density predicted by models for the excitation of SiO masers. It is possible that the SiO masers are excited in clumps with column density even higher than this value. The present results provide useful information for the understanding of the physical conditions of the outer atmospheres in late-type stars.
OASIS: A Multi-Purpose Near-Infrared Camera and Spectrograph
Authors: Okumura Shin-ichiro , Nishihara Eiji , Watanabe Etsuji , Mori Atsushi , Kataza Hirokazu , Yamashita Takuya
Published: March 2014

We have developed a near-infrared (1–2.5 μm) camera and spectrograph, called OASIS (Okayama Astrophysical System for Infrared imaging and Spectroscopy). OASIS was designed for the 188 cm telescope at Okayama Astrophysical Observatory, and developed as a common-use facility instrument. It has two observing capabilities: imaging with a field of view of 4′ × 4′ and long-slit spectroscopy with a resolving power of ∼ 1000. This paper describes the design of OASIS and reports on the total system performance of the camera+telescope+atmosphere at the Okayama Observatory, together with the performance of an array detector, NICMOS 3, which OASIS utilizes.
Hard X-Ray Emission from Massive Star Clusters in a Giant Molecular Cloud NGC 6334
Authors: Sekimoto Yutaro , Matsuzaki Keiichi , Kamae Tuneyoshi , Tatematsu Ken'ichi , Yamamoto Satoshi , Umemoto Tomofumi
Published: March 2014

We report on detection with the ASCA satellite of hard X-rays from far infrared (FIR) star clusters in the giant molecular cloud (GMC) cores of the NGC 6334 star-forming region. Five FIR cores are visible in the hard X-ray band (E > 2 keV), while in the soft X-ray band (E < 2 keV) the emission is absorbed, except for one core. The observed spectra can be fitted with thermal emission from a hot plasma, whose temperature of ∼ 9 keV is significantly higher than those reported of low-mass Class I pre-main-sequence stars (PMSs) ( ∼ 3 keV) in nearby dark clouds and those of OB-type main-sequence stars (∼ 1 keV). The X-ray luminosity of each core is typically 1033 erg s−1 or 103 times that of typical low-mass PMSs. The observed hard X-rays may be emitted from young massive stars and loss-mass/intermediate-mass PMSs in the FIR cores. The observed hard X-ray flux can ionize the inner part (r ∼ 0.3 pc) of the GMC cores at a rate comparable to that by cosmic-ray particles. If the LX/M ratio of ∼ 10−5L⊙/M⊙ observed in NGC 6334 is typical among GMCs, the X-ray flux from all GMCs in the Galaxy ( ∼ 109L⊙) can account for about 20% of the diffuse galactic ridge hard X-ray emission.
First-Epoch VSOP Observation of 3C 380: Kinematics of the Parsec-Scale Jet
Authors: Kameno Seiji , Inoue Makoto , Fujisawa Kenta , Shen Zhi-Qiang , Wajima Kiyoaki
Published: March 2014

The space-VLBI mission VSOP provides high-quality imaging capabilities to investigate fine structures in quasar jets. We report on the first-epoch VSOP observation of the superluminal quasar 3C 380 at λ 6 cm. A high-quality image with a dynamic range of 1:1200 at a resolution of 0.74 mas × 0.36 mas reveals precise structure along the pc-scale jet. Components C2, A, and F, have been identified with those in previous ground-VLBI observations, and an apparent superluminal motion has been confirmed. We find a very straight motion with a constant apparent velocity for components A and F. Each motion vector is almost parallel to each position vector. This suggests a ballistic ejection from the core. In spite of better position accuracy than previous ground-VLBI observations, we cannot confirm any evidence of acceleration or changes of the position angle which were reported in Polatidis and Wilkinson (1998, AAA 069.159.023). We confirmed that the bent jet structure has kept its similarity and direction, compared with previous images. This suggests an oblique shock in relativistic flow rather than the Kelvin-Helmholtz instability.
Models for Accretion-Disk Fluctuations through Self-Organized Criticality Including Relativistic Effects
Authors: Xiong Ying , Wiita Paul J. , Bao Gang
Published: March 2014

The possibility that some of the observed X-ray and optical variability in active galactic nuclei and galactic black hole candidates are produced in accretion disks through the development of a self-organized critical state is reconsidered. New simulations, including more complete calculations of relativistic effects, do show that this model can produce light-curves and power-spectra for the variability which agree with the range observed in optical and X-ray studies of AGN and X-ray binaries. However, the universality of complete self-organized criticality has not quite been achieved. This is mainly because the character of the variations depend quite substantially on the extent of the unstable disk region. If it extends close to the innermost stable orbit, a physical scale is introduced and the scale-free character of self-organized criticality is vitiated. A significant dependence of the power spectrum density slope on the type of diffusion within the disk and a weaker dependence on the amount of differential rotation are noted. When general-relativistic effects are incorporated in the models, additional substantial differences are produced if the disk is viewed from directions far from the accretion disk axis.
Kinematics of the Galaxy from Hipparcos Proper Motions
Authors: Zhu Zi
Published: March 2014

From Hipparcos proper motions, we have analysed the local kinematics of the Milky Way from young O-B5 stars, classical Cepheids, and the late-type K-M giants. The components of solar motion along the direction pointing to the galactic center from the Sun u0 and along the direction pointing to the north galactic pole w0 are approximately 10 km s−1 and 8 km s−1 for all types of stars, while the component pointing to the direction of the galactic rotation varies over a wide range from 13 to 21 km s-1, depending on the type of stars. The galactic rotation derived from O-B5 stars is 269 ± 12 km s-1, which is apparently larger than that recommended by the IAU in 1985 (220 km s-1). Analysing the proper-motion data of O-B5 stars, we clarified a clear stellar warping motion that is a systematic rotation, ∂Vz/∂θ /R = −3.79 ± 1.05 km s−1 kpc−1, of stars around the axis pointing to the galactic center. Taking the kinematical solution from the K–M giants into account, and considering the possible systematic errors remaining in the Hipparcos proper-motion system, the warping motion of O–B5 stars might even be pronounced. The solution from classical Cepheids seems to show a slight contracting motion of the Galaxy in the solar neighbourhood, ∂Vθ/∂θ /R = −2.60±1.07 km s−1 kpc−1, which is along the solar circle. By comparing the thus-derived results, the kinematical discrepancies between each subset of stars are analysed, and the possible reasons for the kinematical differences are discussed.
The VSOP 5 GHz AGN Survey I. Compilation and Observations
Authors: Hirabayashi Hisashi , Fomalont Edward B. , Horiuchi Shinji , Lovell James E. J. , Moellenbrock George A. , Inoue Makoto , Burke Bernard F. , Dewdney Peter E. , Gurvits Leonid I. , Kobayashi Hideyuki , Jauncey David L. , Murata Yasuhiro , McCulloch Peter , Preston Robert A. , Avruch Ian M. , Edwards Philip G. , Dougherty Sean M. , Scott William K. , Frey Sandor , Paragi Zsolt , Kovalev Yuri A. , Popov Misha , Romney Jonathan D. , Schilizzi Richard T. , Shen Zhi-Qiang , Nicolson George , Quick Jonathan , Costa Marco , Dodson Richard , Reynolds John E. , Tzioumis Anastasios K. , Tingay Steven J. , Hong Xiao-Yu , Liang Shi-Guang , Huang Xin-Yong , Wei Wen-Ren , Trigilio Corrado , Tuccari Gino , Nakajima Jun'ichi , Kawai Eiji , Umemoto Tomofumi , Miyaji Takeshi , Fujisawa Kenta , Kawaguchi Noriyuki , Kus Andrzej , Ghigo Frank , Salter Chris , Ghosh Tapasi , Kanevsky Boris , Slysh Vyacheslav , Gunn Alastair , Burgess Paul , Carlson Brent , Del Rizzo David , Taylor Russell , Cannon Wayne , Kameno Seiji , Shibata Kazunori M. , Benson John , Flatters Chris , Hale Andrew , Lewis Craig , Langston Glen , Minter Anthony , Miller Kevin , Smith Joel , Wietfeldt Richard , Altunin Valery , Meier David L. , Murphy David W. , Resch George , Lister Matthew L. , Piner B. Glenn , Jenkins Robert , Border James , Gimeno Jesus
Published: March 2014

The VSOP mission is a Japanese-led project to image radio sources with sub-milliarcsec resolution by correlating the signal from the orbiting 8-m telescope, HALCA, with a global array of telescopes. Twenty-five percent of the scientific time of this mission is devoted to a survey of 402 bright, small-diameter extra-galactic radio sources at 5 GHz. The major goals of the VSOP Survey are statistical in nature: to determine the brightness temperature and approximate structure; to provide a source list for use with future space VLBI missions; and to compare radio properties with other data throughout the EM spectrum. This paper describes: the compilation of a complete list of radio sources associated with active galactic nuclei (AGN); the selection of the subsample of sources to be observed with VSOP; the extensive ground resources used for the Survey; the status of the observations as of 2000 July; the data-analysis methods; and several examples of results from the VSOP Survey. More detailed results from the full sample will be given in future papers.
Structural Model of Molecular Cloud Complexes: Mass, Size, and External Pressure
Authors: Inoue Akio K. , Kamaya Hideyuki
Published: March 2014

We investigate the structure of the molecular cloud complexes (MCCs) as a group of several giant molecular clouds (GMCs) in the Galaxy. We then find that the mass-size relation which has been reported for the GMCs is well-established even for very large MCCs, whose sizes are about 1 kpc. Since the horizontal size of the MCCs is larger than the thickness of the galactic disk, we can no longer consider the MCCs to be spherical. Thus, we construct a structural model of the MCCs, adopting a rectangular-solid geometry. As a result, our model explains the observed mass-size relation of the MCCs very well. From the estimated external pressure around the MCCs, we find that they are in a rough pressure balance with the interstellar medium. Moreover, we find there is an observational deficiency of the MCCs with a large size and surface density. We thus suggest that the external pressure has a significant effect on the structure and evolution of the MCCs. We also discuss the effect of H II regions in the MCCs.
Discovery of 101-s Pulsations from AX J0057.4–7325 in the SMC with ASCA
Authors: Yokogawa Jun , Torii Ken’ichi , Kohmura Takayoshi , Imanishi Kensuke , Koyama Katsuji
Published: March 2014

The results from two ASCA observations of AX J0057.4−7325 = RX J0057.3−7325 are presented. Coherent pulsations with a barycentric period of 101.45 ± 0.07 s were discovered in the second observation. The X-ray spectrum was found to be hard (photon index ∼ 0.9) and unchanged through these observations, except for the flux. The ROSAT archival data show that AX J0057.4−7325 exhibits a flux variation with a factor ≳ 10. A discussion on a possible optical counterpart is given.
LMSA and High-Redshift Dusty Starburst Mergers
Authors: Bekki Kenji , Shioya Yasuhiro
Published: March 2014

By using a new numerical code for deriving the spectral energy distributions of galaxies, we have investigated the time evolution of morphological properties, the star formation rate, and the submillimeter flux at 850 μm in high-redshift (z) dusty starburst mergers with mass ratio (m2) of two disks ranging from 0.1 (minor merger) to 1.0 (major one). We found that the maximum star-formation rate, the degree of dust extinction, and the 850 μm flux are larger for mergers with larger m2. The 850 μm flux from mergers at 1.5 ≤ z ≤ 3.0 in the observer frame is found to be a few mJy for major merger cases, and at most ∼ 100 μJy for minor ones. This result suggests that only high-redshift major mergers are now detected by SCUBA with the current 850 μm detection limit of a few mJy. These results imply that LMSA with the expected detection limit of the order of 10 μJy at 850 μm can be used to study high-redshift mergers with variously different m2, and thus provide an important clue to the formation of galaxies in the high-redshift universe.
Hoyle–Lyttleton Accretion onto Superdisks
Authors: Hanamoto Keishi , Ioroi Masayuki , Fukue Jun
Published: March 2014

We examine Hoyle–Lyttleton accretion onto superdisks, where the mass-accretion rate greatly exceeds the critical one and the luminosity is of the order of the Eddington one. Hoyle–Lyttleton accretion onto a luminous accretion disk is drastically changed from the spherical case, due to the non-spherical nature of disk radiation fields. In edge-on accretion, for example, mass accretion does not cease at $ \Gamma=1$, but continues in the regime of $ \Gamma \geq 1$, where $ \Gamma$ is the disk luminosity normalized by the Eddington one. We found that Hoyle-Lyttleton accretion onto superdisks is not a simple extension of that onto standard accretion disks, where the mass-accretion rate gradually decreases with increasing $ \Gamma$. Instead, in the case of a superdisk, the mass-accretion rate increases with increasing $ \Gamma$. This is due to a geometrical shadowing effect. That is, in contrast to the infinitesimally-thin standard disk, the superdisk has finite thickness. As $ \Gamma$ increases, the relative thickness increases and the shadowing region in the equatorial direction increases. We also briefly discuss the canonical luminosity in the steady state and the system evolution.
Analytical Studies on the Structure and Emission of the SS 433 Jets
Authors: Inoue Hajime , Shibazaki Noriaki , Hoshi Reiun
Published: March 2014

We have studied the structure and emission of the SS 433 jets in the X-ray emitting region and in the inner and hotter portion inside the X-ray emitting region. In order to consider the jet structure from the inner to outer regions we developed a hybrid model combining the conical beam and the model beam, whose cross section grows with the distance more slowly. We found that the jet beams in the inner and hotter portion are of two-temperature and that they emit a large amount of high-energy gamma photons. Our analyses suggest a thick absorbing envelope to exist in the SS 433 system. Based on our results, we discuss the possible acceleration mechanism for the SS 433 jets.
Stability of Terrestrial Protoplanet Systems and Alignment of Orbital Elements
Authors: Ito Takashi , Tanikawa Kiyotaka
Published: March 2014

The dynamical characteristics of terrestrial protoplanet systems have been investigated. Diagrams which show the instability timescale of terrestrial protoplanet systems as a function of the protoplanet separation (we call them CWB diagrams) were analyzed and interpreted. We have produced CWB diagrams for several different initial parameters, mainly with perturbations from Jupiter and Saturn. One-peakedness of the diagrams for small random velocity cases is interpreted from the viewpoint of orbital alignment in protoplanets. The orbital alignment serves as a stabilizer of the protoplanet system by preventing particles from making close encounters. Terrestrial protoplanet systems appear to be most stable where the tidal force produced by perturbers and mutual gravitational interaction among particles balance; in such cases, orbital alignment is realized. Thus, the terrestrial protoplanet systems turn out to be another example of the so-called secular orbit-orbit resonance frequently found in planet-satellite or satellite-ring systems. Gradual breaking of the orbital alignment invokes an instability in protoplanet systems, which can lead to the collisional evolution of protoplanets into the present planets.
Exploring Galaxy Evolution from Infrared Number Counts and Cosmic Infrared Background
Authors: Takeuchi Tsutomu T. , Ishii Takako T. , Hirashita Hiroyuki , Yoshikawa Kohji , Matsuhara Hideo , Kawara Kimiaki , Okuda Haruyuki
Published: March 2014

Recently reported infrared (IR) galaxy number counts and cosmic infrared background (CIRB) all suggest that galaxies have experienced strong evolution sometime in their lifetime. We statistically estimate the galaxy evolution history from these data. We find that an order-of-magnitude increase of the far-infrared (FIR) luminosity at redshift $ z = 0.5$–$ 1.0$ is necessary to reproduce the very high CIRB intensity at 140 $ \mu m$ reported by Hauser et al. (1998, AAA 070.161.559) and decreases to, even at most, a factor of 10 toward $ z \sim 5$, though many variants are allowed within these constraints. This evolution history also satisfies the constraints from the galaxy number counts obtained by IRAS, ISO and, roughly, SCUBA. The rapid evolution of the comoving IR luminosity density required from the CIRB well reproduces the very steep slope of galaxy number counts obtained by ISO. We also estimate the cosmic star formation history (SFH) from the obtained FIR luminosity density, considering the effect of the metal enrichment in galaxies. The derived SFH increases steeply with redshift in $ 0 \lt z \lt 0.75$, and becomes flat or even declines at $ z \gt 0.75$. This is consistent with the SFH estimated from the reported ultraviolet luminosity density. In addition, we present the performance of the Japanese ASTRO-F FIR galaxy survey. We show the expected number counts in the survey. We also evaluate how large a sky area is necessary to derive secure information of galaxy evolution up to $ z \sim 1$ from the survey, and find that at least $ 50$–$ 300\;\mathrm{deg}^2$ is required.
Substructures Revealed by the Sunyaev–Zel’dovich Effect at 150 GHz in a High-Resolution Map of RX J1347$-$1145
Authors: Komatsu Eiichiro , Matsuo Hiroshi , Kitayama Tetsu , Hattori Makoto , Kawabe Ryohei , Kohno Kotaro , Kuno Nario , Schindler Sabine , Suto Yasushi , Yoshikawa Kohji
Published: March 2014

We report on mapping observations toward the region of the most luminous X-ray cluster, RX J1347$-$1145 ($ z=0.45$), through the Sunyaev–Zel’dovich effect at 21 GHz and 150 GHz with the Nobeyama 45-m telescope. While a low angular resolution image at 21 GHz (beam-size $ \sigma_\mathrm{FWHM}$ of 76$ {}^{\mathrm{\prime\prime}}$) shows a consistent feature with the ROSAT/HRI X-ray image, a higher angular resolution image ($ \sigma_\mathrm{FWHM} =13^{\prime\prime}$) at 150 GHz reveals complex morphological structures of the cluster region, which cannot be simply described by the spherical isothermal $ \beta$-model. If such inhomogeneous morphological features prove to be generic for high-redshift clusters, distance measurements to the clusters based on their Sunyaev–Zel’dovich data with low angular resolution imaging should be interpreted with caution.
The X-Ray Structure of the Supernova Remnant 3C 400.2
Authors: Yoshita Kumi , Tsunemi Hiroshi , Miyata Emi , Mori Koji
Published: March 2014

We present here the results of an X-ray study of the supernova remnant 3C 400.2 (G53.6$-$2.2) using the ASCA data. 3C 400.2 has an unusual morphology at radio wavelengths, suggesting two SNRs superposed along the same line of sight, whereas its X-ray emission is known to be centrally peaked. We investigated the X-ray spectral variation across the remnant using the ASCA GIS and the ROSAT PSPC data. The X-ray spectra can be well fitted by thin thermal plasma models. However, there is no significant variation in the temperature and the ionization parameter across the remnant. We conclude that it is a single SNR rather than two overlapping SNRs. The centrally peaked X-ray morphology and the thin thermal emission with nearly cosmic abundances indicate that 3C 400.2 belongs to a class of “mixed-morphology SNRs”. We found that the physical parameters of 3C 400.2 are similar to those of other mixed-morphology SNRs. The morphology of 3C 400.2 can be explained by a supernova explosion occurring near to the edge of an interstellar cloud.
ASCA Observations of the Twin Supernova Remnants in the Large Magellanic Cloud, DEM L316
Authors: Nishiuchi Mamiko , Yokogawa Jun , Koyama Katsuji , Hughes John P.
Published: March 2014

We report results from an ASCA X-ray study of DEM L316, an emission nebula in the Large Magellanic Cloud (LMC) consisting of two closely-spaced supernova remnants (SNRs). The SIS image shows separate X-ray sources located at the positions of the two radio- and optically-emitting SNR shells, 0547$-$69.7A and 0547$-$69.7B (hereafter, shell A and shell B). The individual X-ray spectrum of each shell is well described by optically-thin thermal emission, although the characteristics of the emission differ in important details between them. Shell A exhibits strong iron L emission, which we attribute to the presence of iron-rich ejecta, leading to the suggestion that this SNR originates from a type Ia SN, an explosion of a moderate mass progenitor. Shell B, on the other hand, has a chemical composition similar to that of the interstellar medium of the LMC, and so its X-ray emission is dominated by swept-up matter. The different spectral features strongly disfavor the hypothesis that the two shells are due to one supernova explosion into an interconnected bubble. We could not obtain evidence which positively supports the collision between two SNRs.
High-Dispersion Spectra of NH2 in the Comet C/1999S4 (LINEAR): Excitation Mechanism of the NH2 Molecule
Authors: Kawakita Hideyo , Watanabe Jun-ichi , Kinoshita Daisuke , Abe Shinsuke , Furusho Reiko , Izumiura Hideyuki , Yanagisawa Kenshi , Masuda Seiji
Published: March 2014

We carried out a high-dispersion spectroscopic observation of the comet C/1999S4 (LINEAR) on 2000 July 8.75 (UT). The $ \mathrm{NH}_2$$ \tilde{\mathrm{A}}(0,10,0)$-$ \tilde{\mathrm{X}}(0,0,0)$ and $ \tilde{\mathrm{A}}(0,9,0)$-$ \tilde{\mathrm{X}}(0,0,0)$ bands were extracted from the observed spectrum and compared with the modeled spectra. We developed a fluorescence equilibrium model for the $ \mathrm{NH}_2$, in which $ \tilde{\mathrm{A}}(0,v_2^{\prime},0)$-$ \tilde{\mathrm{X}}(0,0,0)$ transitions and the radiative relaxation among the rotational levels in $ \tilde{\mathrm{X}}(0,0,0)$ were considered. The rotational structure of the spin doublet ($ F_1$ and $ F_2$ levels) and the Swings effect were considered in the model. The modeled spectra are consistent with the observed spectra of the $ \tilde{\mathrm{A}}(0,10,0)$ and $ \tilde{\mathrm{A}}(0,9,0)$ bands. Our results show that the fluorescence excitation and the radiative relaxation processes are dominant for $ \mathrm{NH}_2$ in a coma of the comet at $ \sim$ 1 AU from the Sun.
The Dense Plasma Torus around the Nucleus of an Active Galaxy NGC1052
Authors: Kameno Seiji , Sawada-Satoh Satoko , Inoue Makoto , Shen Zhi-Qiang , Wajima Kiyoaki
Published: March 2014

A subparsec-scale dense plasma torus around an active galactic nucleus is unveiled. We report on very-long-baseline interferometry (VLBI) observations at 2.3, 8.4, and 15.4 GHz towards the active galaxy NGC1052. The convex spectra of the double-sided jets and the nucleus imply that synchrotron emission is obscured through free–free absorption (FFA) by the foreground cold dense plasma. A trichromatic image was produced to illustrate the distribution of the FFA opacity. We found a central condensation of the plasma which covers about 0.1 pc and 0.7 pc of the approaching and receding jets, respectively. A simple explanation for the asymmetric distribution is the existence of a thick plasma torus perpendicular to the jets. We also found an ambient FFA absorber, whose density profile can be ascribed to a spherical distribution of the isothermal King model. The coexistence of torus-like and spherical distributions of the plasma suggests a transition from radial accretion to rotational accretion around the nucleus.
ASCA Observation of the Superluminal Jet Source GRO J1655–40 in the 1997 Outburst
Authors: Yamaoka Kazutaka , Ueda Yoshihiro , Inoue Hajime , Nagase Fumiaki , Ebisawa Ken , Kotani Taro , Tanaka Yasuo , Zhang Shang Nan
Published: March 2014

We report on the results of an ASCA observation of the Galactic jet source GRO J1655–40 performed from 1997 February 25 to February 28 covering a full orbital period (2.62 d). The averaged 2–10 keV flux was about 1.1 Crab. An absorption line feature centered at 6.8 keV was detected both in the GIS and SIS spectra. We interpret this as a blend of two resonance-absorption $\mathrm{K}\alpha$ lines from H-like and He-like iron ions. We can consistently explain both the ASCA spectra and the simultaneous RXTE/PCA spectrum by a combination of K-absorption lines and K-absorption edges of iron ions. The fact that the absorption line is stably present over the whole orbital phase implies that the distribution of the highly ionized plasma is not affected by the companion star, which is consistent with its presence around the black hole. A curve of growth analysis shows that the plasma contains velocity dispersion along the line-of-sight larger than $300~\mathrm{km}~\mathrm{s}^{-1}$ attributed to bulk motions. It is probably a part of a geometrically thick accretion flow in turbulent motions with velocities of $500$-$1600~\mathrm{km}~\mathrm{s}^{-1}$ at an estimated radius of $\sim10^{10}~\mathrm{cm}$.
The Radio and Gamma-Ray Luminosi0074ies of Blazars
Authors: Zhang L. , Cheng K. S. , Fan J. H.
Published: March 2014

Based on the $\gamma$-ray data of blazars in the third EGRET catalog and radio data at 5 GHz, we studied the correlation between the radio and $\gamma$-ray luminosities using two statistical methods. The first method was the partial correlation analysis method, which indicates that there exist correlations between the radio and $\gamma$-ray luminosities in both high and low states as well as in the average case. The second method involved a comparison of expected $\gamma$-ray luminosity distribution with the observed data using the Kolmogorov–Smirnov (KS) test. In the second method, we assumed that there is a correlation between the radio and $\gamma$-ray luminosities and that the $\gamma$-ray luminosity function is proportional to the radio luminosity function. The KS test indicates that the expected gamma-ray luminosity distributions are consistent with the observed data in a reasonable parameter range. Finally, we used different $\gamma$-ray luminosity functions to estimate the possible ‘observed’ $\gamma$-ray luminosity distributions by GLAST.
Radiatively-Driven Relativistic Accretion Disk Winds
Authors: Hirai Yasuo , Fukue Jun
Published: March 2014

We theoretically examined relativistic disk winds driven by disk radiation fields. For the present purpose, we quantitatively caluculated the full components of radiation fields produced by a standard accretion disk around Schwarzschild and extreme Kerr black holes, under the pseudo-Newtonian gravity and special relativity. The typical strength of radiation fields of disks around the Schwarzschild hole reduces by about 50%, whereas that around the extreme Kerr hole increases by about ten times, as compared with the Newtonian case. We found that the wind is easy to blow off from the disk around the Kerr hole, although it becomes difficult from the disk around the Schwarzschild hole, as long as the accretion rate is subcritical. In the extreme Kerr case the maximum terminal speed is about $0.5c$ for the critical accretion rate.
Dynamic Current Injection into Magnetic Loops in Active Regions I. Supplies of Energy and Mass to Active-Region Corona in the Form of Dynamic Loop Brightenings
Authors: Uchida Yutaka , Miyagoshi Takehiro , Yabiku Tomohide , Cable Samuel , Hirose Shigenobu
Published: March 2014

One of the discoveries by Yohkoh is that a large part of the soft X-ray emission from the active-region corona comes from hot gas injected dynamically into magnetic loops from below. We propose that the major part of the supply of energy and mass to active region corona may be due to a dynamical leakage of magnetic twists produced in the subphotospheric convection layer. These twists naturally propogate out along the magnetic field to the active region corona as a large-amplitude torsional Alfvén-wave packet (TAWP, equivalent to a coaxially self-closed packet of MHD current), and the active-region corona is a dumping ground for such currents. These TAWP’s, which are passively produced in the dominant gas motion in the convection layer, dynamically influence the lower pressure gas as they propagate out into the chromosphere and the corona. The flux tube in the corona is pinched near the axis and heated. The pinched region propagates dynamically with the Alfvén velocity along the magnetic loop, driving the pinch-heated high-temperature gas into a spinning jet (a sweeping pinch). This may explain the supply of energy and mass to active-region corona in the form of the active-region loop brightenings found by Yohkoh.
Dynamic Current Injection into Magnetic Loops in Active Regions II. A 3D Magnetodynamic Model for Loop Flares
Authors: Miyagoshi Takehiro , Uchida Yutaka , Yabiku Tomohide , Hirose Shigenobu , Cable Samuel
Published: March 2014

We have studied propagation along magnetic flux tubes in the active-region corona of large-amplitude torsional Alfvén wave packets (TAWP’s) coming up from a subphotospheric convection zone. TAWP’s can serve to transfer magnetic energy from the high-$\beta (\beta = P_{\mathrm{g}}/P_{\mathrm{m}})$ subphotospheric region to the low-$\beta$ coronal region. They dump part (or all) of their energy in the low-$\beta$ coronal region, which may result in very high temperature-plasma observed in X-rays (and in high energy particles). The supply of TAWPs from the photosphere, considered to be inefficient because the Alfvén velocity in the photosphere is small, turns out to be sufficiently effective for large-amplitude TAWP’s. This is due to the magnetic buoyancy acting on the magnetic twist packet and to the non-linear effect of squeezing out the gas from the twisted part of loops when it comes up near the photosphere. Both of these effects enhance the speed of emergence of the twist. We propose that loop flares may be due to the transport of energy and mass by torsional Alfvén waves. They may be the result of energy conversion of the magnetic twists and the kinetic energy of the accelerated hypersonic flows into thermal energy when two such TAWP’s collide high in a coronal loop. In order for such a collision of TAWP’s to occur, a TAWP is injected from one footpoint of a loop whilst another TAWP, from the other footpoint, is still propagating along the loop. The collision of these two TAWP’s at a high part of the loop explains the creation of a hyperhot region. The acceleration of high-energy particles is also explained as being due to the Fermi-I process between the approaching two hypersonic magnetic shocks.
Interpolation of One - and Two-Dimensional Images with Pixelwise Photon Number Conservation
Authors: Sakurai Takashi , Shin Junho
Published: March 2014

The interpolation of one - and two-dimensional images is considered. The usual linear or cubic spline interpolations try to connect given data points. On the other hand, image data give area integrals of the radiation intensity (i.e., photon counts) over pixels. Based on variational principles, we have developed schemes of quadratic and fourth-order polynomial interpolation which reproduce the given pixelwise photon counts exactly. These methods were tested on some simple examples and showed satisfactory results.
Tidal Truncation of Gas Replenishment and Global Suppression of Galactic Star Formation in Distant Clusters
Authors: Bekki Kenji , Couch Warrick J. , Shioya Yasuhiro
Published: March 2014

Recent spectroscopic observations of galaxies in distant clusters have revealed that the rate of star formation in star-forming galaxies is significantly suppressed with respect to their counterparts in the field at a similar redshift. It is, however, highly uncertain which physical processes are responsible for this suppression. We present the results of a numerical investigation of how the global tidal field of a cluster dynamically influences the reservoir of halo gas surrounding a disk galaxy as it falls into the cluster from the surrounding field. We find that the tidal field of the cluster efficiently removes the halo gas from the galaxy, thereby halting its accretion onto the disk, and thus the fueling of star formation within. This effectively truncates the galaxy’s star formation. We also find that this tidal truncation does not depend very strongly on the orbit of the disk with respect to the center of the cluster. These results suggest that the global tidal field of clusters is capable of causing a widespread and uniform suppression of star formation in galaxies accreted by the cluster. In light of these results, we discuss the importance of this tidal truncation of the gas supply in the formation of S0 galaxies in clusters.
X-Ray Probing of the Central Regions of Clusters of Galaxies
Authors: Makishima Kazuo , Ezawa Hajime , Fukazawa Yasushi , Honda Hirohiko , Ikebe Yasushi , Kamae Tuneyoshi , Kikuchi Ken’ich , Matsushita Kyoko , Nakazawa Kazuhiro , Ohashi Takaya , Takahashi Tadayuki , Tamura Takayuki , Xu Haiguang
Published: March 2014

The results on ASCA X-ray study of the central regions of medium-richness clusters of galaxies are summarized, while emphasizing the differences between cD and non-cD clusters. The intra-cluster medium (ICM) is likely to consist of two (hot and cool) phases within $\sim 100$kpc of a cD galaxy, where the ICM metallicity is also enhanced. In contrast, the ICM in non-cD clusters appears to be isothermal with a small metallicity gradient right of the center. The gravitational potential exhibits a hierarchical nesting around cD galaxies, while a total mass-density profile with a central cusp is indicated for a non-cD cluster, Abell 1060. The iron-mass-to-light ratio of the ICM decreases toward the center in both types of clusters, although it is radially constant in peripheral regions. The silicon-to-iron abundance ratio in the ICM increases with the cluster richness, but remains close to the solar ratio around cD galaxies. These overall results are interpreted without appealing to the popular cooling-flow hypothesis. Instead, an emphasis is put on the halo-in-halo structure formed around cD galaxies.