bluuebunny/crossref_metadata_2025_split huggingface dataset:
ASTE Simultaneous HCN (4–3) and HCO+(4–3) Observations of the Two Luminous Infrared Galaxies NGC 4418 and Arp 220
Authors: Imanishi Masatoshi , Nakanishi Kouichiro , Yamada Masako , Tamura Yoichi , Kohno Kotaro 
Published: March 2014

Abstract
We report the results of HCN ($J =$ 4–3) and HCO$^{+}$($J =$ 4–3) observations of two luminous infrared galaxies, NGC 4418 and Arp 220, made using the Atacama Submillimeter Telescope Experiment (ASTE). The ASTE wide-band correlator provided simultaneous observations of HCN (4–3) and HCO$^{+}$(4–3) lines, and a precise determination of their flux ratios. Both galaxies showed high HCN (4–3) to HCO$^{+}$(4–3) flux ratios of $&gt;$2, possibly due to AGN-related phenomena. The $J =$ 4–3 to $J =$ 1–0 transition flux ratios for HCN (HCO$^{+}$) are similar to those expected for fully thermalized (sub-thermally excited) gas in both sources, in spite of HCN’s higher critical density. If we assume collisional excitation and neglect an infrared radiative pumping process, our non-LTE analysis suggests that HCN traces gas with significantly higher density than HCO$^{+}$. In Arp 220, we separated the double-peaked HCN (4–3) emission into eastern and western nuclei, based on velocity information. We confirmed that the eastern nucleus showed a higher HCN (4–3) to HCN (1–0) flux ratio, and thus contained a larger amount of highly excited molecular gas than the western nucleus.
First R and I Lights and Their Photometric Analyses of GSC 02393–00680
Authors: Liang Liu , Sheng-Bang Qian , Jia-Jia He , Lin-Jia Li , Wen-Ping Liao 
Published: March 2014

Abstract
We obtained complete $R$ and $I$ light curves of GSC 02393$-$00680 in 2008 and analyzed them with the 2003 version of the W–D code. It has been shown that GSC 02393$-$00680 is a W-type shallow contact binary system with a high mass ratio, $q =$ 1.600, and a degree of contact factor, $f =$ 5.0% ($\pm$1.3%). It will be a good example to check up on the TRO theory. A period investigation based on all available data suggests that the system has a small-amplitude period oscillation ($A_3 =$ 0$.^{\rm d}$0030; $T_3 =$ 1.92 years). This may indicate that it has a moderate-mass close third body, which is similar to XY Leo.
Size Evolution of Early-Type Galaxies and Massive Compact Objects as Dark Matter
Authors: Totani Tomonori 
Published: March 2014

Abstract
The dramatic size evolution of early-type galaxies from $z\sim$ 2 to 0 poses a new challenge in the theory of galaxy formation, which may not be explained by the standard picture. It is shown here that the size evolution can be explained if the non-baryonic cold dark matter is composed of compact objects having a mass scale of $\sim$10$^{5}M_\odot$. This form of dark matter is consistent with, or only weakly constrained by the currently available observations. The kinetic energy of the dark compact objects is transferred to stars by dynamical friction, and stars around the effective radius are pushed out to larger radii, resulting in a pure size evolution. This scenario has several good properties to explain the observations, including the ubiquitous nature of size evolution and faster disappearance of higher density galaxies.
Spectral Index and Core-Dominance Parameter in Blazars
Authors: Fan Jun-Hui , Yang Jiang-He , Tao Jun , Huang Yong , Liu Yi 
Published: March 2014

Abstract
In this paper, we discuss the relationship between the spectral index and the core-dominance parameter for blazars (BL Lacertae objects and flat spectrum radio quasars). To do so, we calculated the spectral indexes for 38 BL Lacertae objects using the preliminary data of the University of Michigan Radio Astronomy Observatory (UMRAO) with those for flat spectrum radio quasars from our previous paper (2008, PASJ, 60, 707). For the core-dominance parameters, we mainly calculated them from the flux densities given by Kovalev et al. (2005, AJ, 130, 2473). We have compiled a list of core-dominance parameters for some sources from the available literature. In this sense, we obtained a sample of 119 blazars (38 BL Lacertae objects and 81 flat spectrum radio quasars). From the relevant data, we found that the spectral index is associated with the core-dominance parameter, and tried to explain this association using a relativistic beaming model. In addition, we made a comparison of the properties of BL Lacertae objects and flat spectrum radio quasars. We concluded that the association between spectral index and core-dominance parameter is perhaps due to a relativistic beaming effect.
A New Candidate of a Cluster of Galaxies, 2XMM J045637.2+522411
Authors: Yamauchi Shigeo , Ueno Masaru , Bamba Aya , Koyama Katsuji 
Published: March 2014

Abstract
We present XMM-Newton and Suzaku results of an X-ray source, 2XMM J045637.2$+$522411, found during an observation of a galactic supernova remnant (SNR), G156.2$+$5.7. By comparing its radial profile with the point-spread function, we found that 2XMM J045637.2$+$522411 is an extended source. X-ray spectra exhibited a line-like structure at 5.7–5.8 keV. Since no abundant element emits an X-ray line at 5–6 keV in the rest-frame, and the most intense emission line in the 5–7 keV energy band is a Fe-K line, the line is likely to be a redshifted Fe-K line. The overall spectra can be represented by a thin-thermal plasma model with a temperature of 3–4 keV and a redshift of 0.15–0.17. No intensity variation was found in the light curve. The observational results indicate that 2XMM J045637.2$+$522411 is likely to be a cluster of galaxies.
FAST: A Fully Asynchronous Split Time-Integrator for a Self-Gravitating Fluid
Authors: Saitoh Takayuki R. , Makino Junichiro 
Published: March 2014

Abstract
We describe a new algorithm for the integration of self-gravitating fluid systems using SPH method. We split the Hamiltonian of a self-gravitating fluid system into the gravitational potential and others (kinetic and internal energies), and used different time-steps for their integrations. The time integration was done in the way similar to that used in the mixed-variable or multiple stepsize symplectic schemes. We performed three test calculations. The first test was spherical collapse, and the second test was an explosion. As the third test, we also performed a realistic test, in which the initial model was taken from a simulation of merging galaxies. In all test calculations, we found that the number of time-steps for gravitational interaction were reduced by nearly an order of magnitude when we adopted our integration method. In the case of the realistic test, in which the dark-matter potential dominates the total system, the total calculation time was significantly reduced. The simulation results were almost the same as those of simulations with the ordinary individual time-step method. Our new method has achieved good performance without sacrificing the accuracy of the time integration.
Suzaku Discovery of a Hard X-Ray Tail in the Persistent Spectra from the Magnetar 1E 1547.0$-$5408 during its 2009 Activity
Authors: Enoto Teruaki , Nakazawa Kazuhiro , Makishima Kazuo , Nakagawa Yujin E. , Sakamoto Takanori , Ohno Masanori , Takahashi Tadayuki , Terada Yukikatsu , Yamaoka Kazutaka , Murakami Toshio , Takahashi Hiromitsu 
Published: March 2014

Abstract
The fastest-rotating magnetar 1E 1547.0$-$5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28–29, 7 d after the onset of its latest bursting activity. After removing burst events, the absorption-uncorrected 2–10 keV flux of the persistent emission was measured with the XIS as 5.7 $\times$ 10$^{-11} $erg cm$^{-2} $s$^{-1}$, which is 1–2 orders of magnitude higher than was measured in 2006 and 2007 when the source was less active. This persistent emission was also detected significantly with the HXD in $&gt; $10 keV up to at least $\sim $110 keV, with an even higher flux of 1.3 $\times$ 10$^{-10} $erg cm$^{-2} $s$^{-1}$ in 20–100 keV. The pulsation was detected at least up to 70 keV for a period of 2.072135$ \pm $0.00005 s, with a deeper modulation than was measured in a fainter state. The phase-averaged 0.7–114 keV spectrum was reproduced by an absorbed blackbody emission with a temperature of 0.65$ \pm $0.02 keV, plus a hard power-law with a photon index of $\sim $1.5. At a distance of 9 kpc, the bolometric luminosity of the blackbody and the 2–100 keV luminosity of the hard power-law are estimated to be (6.2$ \pm $1.2) $\times$ 10$^{35} $erg s$^{-1}$ and 1.9 $\times$ 10$^{36} $erg s$^{-1}$, respectively, while the blackbody radius becomes $\sim $5 km. Although the source has not been detected significantly in hard X-rays during the past fainter states, a comparison of the present and past spectra at energies below 10 keV suggests that the hard component is more enhanced than the soft X-ray component during the period of persistent activity.
Age-Determination Method of Pre-Main Sequence Stars with High-Resolution I-Band Spectroscopy
Authors: Takagi Yuhei , Itoh Yoichi , Oasa Yumiko 
Published: March 2014

Abstract
We present a new method for determining the age of late-K type pre-main sequence (PMS) stars by deriving their surface gravity from high-resolution I-band spectroscopy. Since PMS stars contract as they evolve, their age can be estimated by the surface gravity. We used the equivalent width ratio (EWR) of nearby absorption lines that are free of uncertainties due to veiling, to make a surface-gravity diagnostic of PMS stars. The ratios of Fe (8186.7 Å and 8204.9 Å) and Na (8183.3 Å and 8194.8 Å) absorption lines were calculated for giants, main-sequence stars, and weak-line T Tauri stars. The samples were nearly equal in effective temperature. The EWR of Fe and Na, Fe$/$Na, decreases significantly with increasing surface gravity, indicating that Fe$/$Na is a desirable diagnostic tool for deriving the surface gravity of PMS stars. The surface gravity of PMS stars with 0.8$ M_{\odot}$ can be determined with accuracies of 0.1–0.2, which estimates the age of PMS stars within a factor of 1.5, on average.
Orbital Period Study of the RS CVn-Type Binary WW Draconis
Authors: Tian Yong Po , Ou Yong Kang , Zhang Jian Fu , Zhang Wei Xi , Xiang Fu Yuan 
Published: March 2014

Abstract
The orbital period variation of the RS CVn-type binary system WW Dra was studied based on all available times of light minima. We confirmed that the orbital period of the binary shows a cyclical change with a large amplitude of 0.2495 days. We discussed in detail the mechanisms that could explain the period change of the system, especially the light-travel time orbit of a tertiary component or magnetic activity cycle. Of these two mechanisms, we find that the latter is more plausible.
SiO Maser Survey off the Galactic Plane: A Signature of Streaming Motion
Authors: Deguchi Shuji , Shimoikura Tomomi , Koike Kazutaka 
Published: March 2014

Abstract
A group of Mira variables in the solar neighborhood shows unusual spatial motion in the Galaxy. To study this motion on a much larger scale in the Galaxy, we newly surveyed 134 evolved stars off the Galactic plane by SiO maser lines, obtaining accurate radial velocities of 84 detected stars. Together with the past data of SiO maser sources, we analyzed the radial-velocity data of a large sample of sources distributed in a distance range of about 0.3–6 kpc in the first Galactic quadrant. At Galactic longitudes between 20$^{\circ}$ and 40$^{\circ}$, we found a group of stars with large negative radial velocities, which deviate by more than 100 km s$^{-1}$ from the Galactic rotation. We show that these deviant motions of maser stars are created by periodic gravitational perturbation of the Bulge bar, and that the effect appears most strongly at radii between corotation and outer Lindblad resonances. The resonance effect can explain the displacement of positions from the Galactic plane as well.
Radiative Spectra from Disk Corona and Inner Hot Flow in Black-Hole X-Ray Binaries
Authors: Kawabata Ryoji , Mineshige Shin 
Published: March 2014

Abstract
To understand the origin of hard X-ray emissions from black-hole X-ray binaries during their low/hard states, we calculate the X-ray spectra of black-hole accretion flow for the following three configurations of hot and cool media: (a) an inner hot-flow and a cool outer disk (inner hot-flow model), (b) a cool disk sandwiched by disk coronae (disk-corona model), and (c) a combination of those two (hybrid model). The basic features we require for successful models are (i) significant hard X-ray emission whose luminosity exceeds that of soft X-rays, (ii) high hard X-ray luminosities in the range of (0.4–30) $\times$ 10$^{37}$erg s$^{-1}$, and (iii) the existence of two power-law components in the hard X-ray band with photon indices of $\Gamma_{\rm s} \sim$ 2 $\gt \Gamma_{\rm h}$, where $\Gamma_{\rm s}$ and $\Gamma_{\rm h}$ are the photon indices of the softer ($\lt$ 10 keV) and harder ($\gt$10 keV) power-law components, respectively. The contributions by non-thermal electrons or time-dependent evolution are not considered. We find that Models (a) and (b) can be ruled out, since the spectra are always dominated by the soft component, and since only one power-law component, at most, can be reproduced. Only Model (c) can account for sufficiently strong hard X-ray emissions, as well as the existence of the two power-law components, for a large ratio of the accretion rate in the corona to that in the thin disk. The outer-disk corona (where the Compton $y$-parameter is smaller, $y \lt$ 1) produces the softer power-law component with a photon index of $\Gamma_{\rm s} \sim$ 2, whereas the inner hot-flow (where $y \gtrsim$ 1) generates the harder component with $\Gamma_{\rm h} \lt $ 2. This model can also account for the observed relationship between the photon index and the reflection fraction.
Spin–Orbit Alignment of the TrES-4 Transiting Planetary System and Possible Additional Radial-Velocity Variation
Authors: Narita Norio , Sato Bun’ei , Hirano Teruyuki , Winn Joshua N. , Aoki Wako , Tamura Motohide 
Published: March 2014

Abstract
We report new radial velocities of the TrES-4 transiting planetary system, including observations of a full planetary transit, with the High Dispersion Spectrograph on the Subaru 8.2 m telescope. Modeling of the Rossiter–McLaughlin effect indicates that the exoplanet TrES-4b has a sky-projected angle of $\lambda =$ 6${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$3 $\pm $ 4${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$7 between its orbital axis and the host star’s spin one. The close spin–orbit alignment of TrES-4b seems to argue against a migration history involving planet–planet scattering or Kozai cycles, although there are two nearby faint stars that might be binary companion candidates. A comparison of our out-of-transit data from four different runs suggests that the star exhibits a radial-velocity variability of $\sim $20 m s$^{-1}$ in excess of a single Keplerian orbit. Although the cause of the excess variability is unknown, we discuss various possibilities such as systematic measurement errors, starspots or other intrinsic motions, and additional companions besides the transiting planet.
Water Production Rate of the Jupiter-Family Comet 46P/Wirtanen in the 2008 Apparition with the Subaru Telescope/IRCS
Authors: Kobayashi Hitomi , Kawakita Hideyo 
Published: March 2014

Abstract
We present the water production rate of comet 46P/Wirtanen in its 2008 apparition, determined from high-dispersion near-infrared spectroscopic observations. Comet 46P/Wirtanen, one of Jupiter-family comets, was the target of the ROSETTA mission in the past. Observations of comet 46P were carried out in the middle of 2008 February with the Subaru telescope and Infrared Camera and Spectrograph (IRCS) instrument. We detected three water emission lines, and the water production rate was determined to be (1.7$\ \pm\ $0.2) $\times$ 10$^{28}\ $molecules s$^{-1}$ on 2008 February 19 near the perihelion passage of the comet. This was the first direct detection of water in the coma of comet 46P. We compared our result with the water production rate determined from radio observations near the perihelion passage in the same apparition, and we found that the rate of radio observations is consistent with our value within $\ \pm\ $2$\ \sigma$ errors. We also compared the water production rates observed in the 2008 apparition with other results observed in the 1997 apparition. We found that the water production rates in 2008 are consistent with those in 1997. There was no secular change of water production rates around its perihelion passage in recent decades for comet 46P.
A Multicolour Photometric Study for the W Ursae Majoris Type Binary LR Camelopardalis
Authors: Yang Yuan-Gui , Dai Hai-Feng 
Published: March 2014

Abstract
A CCD multicolour photometry for the eclipsing binary LR Camelopardalis, obtained on 2008 December 19 and 2010 January 29 and 30 at the Xinglong Station of NAOC, is presented. Using the Wilson–Devinney binary code, a photometric solution was simultaneously derived from $BVR$ light curves. The results show that LR Cam belongs to a W-type contact binary, with a mass ratio of $q =$ 0.300(1) and an overcontact degree of $f =$ 23.5(5)%, indicating that LR Cam is a weak-contact binary. The asymmetric light curves (i.e., the O’Connell effect) were modeled by a dark spot on the more massive component. From the ($O-C$) curve of LR Cam, it is found that the orbital period shows a sine-like variation superimposed on a secular period increase. The quasi-sinusoidal variation, with $A =$ 0$^{\rm d}\!\!\!.$0039(1), $P_{3} =$ 5.34(2) yr, and $e^\prime =$ 0.56(3), may more likely result from a light-time effect via the presence of a third body. The long-term period increases at a rate of $dP/dt = +$0.65(9) $\times$ 10$^{-7}\ $d yr$^{-1}$, which may be interpreted by mass transfer from the less-massive component to the more-massive one. With mass transferring, LR Cam may evolve into a broken-contact binary.
Testing the Atacama Compact Array Phase-Correction Scheme Using the Submillimeter Array
Authors: Matsushita Satoki , Chen Yu-Lin 
Published: March 2014

Abstract
We conducted observational tests of a phase-correction scheme for the Atacama Compact Array (ACA) of the Atacama Large Millimeter and submillimeter Array (ALMA) using the Submillimeter Array (SMA) on Mauna Kea in Hawaii. Interferometers at millimeter and submillimeter waves are highly affected by refraction induced by water vapor in the troposphere, which results in phase fluctuations. The ACA is planning to compensate for the atmospheric phase fluctuation using phase information of the outermost antennas with interpolating into the inner antennas by creating a phase screen. The interpolation and extrapolation phase-correction schemes using phase screens have been tested by the SMA to study how effective they are. We produce a plane of wavefront (phase screen) from the phase information of three antennas for each integration, and this phase screen is used for interpolating the phase of the inner antenna and extrapolating that of the outer one. The interpolation scheme apparently obtains improved results, suggesting that the ACA phase-correction scheme works well. On the other hand, the extrapolation one often does not improve the results. After extrapolation, unexpectedly large phase fluctuations occur in the phases of the antennas at a distance of $\sim\ $140 m away from the center of the three reference antennas. The directions of these antennas are almost perpendicular to that of the wind, suggesting that the phase fluctuations can be well explained by the frozen phase screen in the atmosphere.
Solar-Type Magnetic Reconnection Model for Magnetar Giant Flares
Authors: Masada Youhei , Nagataki Shigehiro , Shibata Kazunari , Terasawa Toshio 
Published: March 2014

Abstract
We present a theoretical model describing magnetar giant flares on the basis of solar flare/coronal mass ejection theory. In our model, preflare activity plays a crucial role in driving evaporating flows and supplying baryonic matter to the magnetosphere. Loaded baryonic matter, which is called “prominence”, is then gradually uplifted via crustal cracking while maintaining a quasi-force-free equilibrium of the magnetosphere. Finally, the prominence is erupted by a magnetic pressure force due to the loss of equilibrium triggered by explosive magnetic reconnection. A giant flare should be induced as a final outcome of prominence eruption accompanied by large-scale field reconfigurations. An essential difference between the solar flare and the magnetar flare is the control process of their evolutionary dynamics. The flaring activity on magnetars is mainly controlled by the radiative process, unlike a solar flare governed by electron conduction. It is full of suggestion that our model accounts for the physical properties of an extraordinary giant flare observed on 2004 December 27 from SGR 1806$-$20, including the source of baryonic matter loaded in the expanding ejecta observed after the giant burst.
A Period Investigation of the δ Scuti Star AN Lyncis
Authors: Lin-Jia Li , Sheng-Bang Qian , Fu-Yuan Xiang 
Published: March 2014

Abstract
We present 9 new times of light maximum of the $\delta$ Scuti star AN Lyncis based on photometric observations from the years 2008–2010. Together with 194 times of the light maximum from the literature, a detailed study of the $O-C$ diagram with data spanning over three decades has led to a new ephemeris formula. A cyclic change in the $O-C$ diagram is also suggested by the $O-C$ method, where the cyclic period is about 17.7 yr. With the available data, we have found that the Fourier amplitude of AN Lyncis is changing in sync with a change of the pulsation period. Simple arguments are given for a possible mechanism affecting the cyclic change.
On the Light-Bending Model of X-Ray Variability of MCG –6–30–15
Authors: Życki Piotr T. , Ebisawa Ken , Niedźwiecki Andrzej , Miyakawa Takehiro 
Published: March 2014

Abstract
We have applied the light-bending model of X-ray variability to Suzaku data of the Seyfert 1 galaxy MCG $-$6–30–15. We analyzed the energy dependence of the root mean square variability, and discussed conditions necessary for the model to explain the characteristic decrease of the source variability at around 5–8 keV. A model, where the X-ray source moves radially rather than vertically close to the disk surface, can indeed reproduce the reduced variability near the energy of the Fe K${\alpha}$ line, although the formal fit quality is poor. The model then predicts the energy spectra, which can be compared to observational data. The spectra are strongly reflection dominated, and do not provide a good fit to Suzaku spectral data of the source. The inconsistency of this result with some previous claims can be traced to our using data in a broader energy band, where the effects of a warm absorber in the spectrum cannot be neglected.