bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral Variation of the Seyfert 1 Galaxy MCG –6–30–15 Observed with Suzaku
Authors: Miyakawa Takehiro , Ebisawa Ken , Terashima Yuichi , Tsuchihashi Fuminori , Inoue Hajime , Zycki Piotr
Published: March 2014

We have investigated the spectral variation of the Seyfert 1 galaxy MCG $-$6–30–15 observed with Suzaku in 2006 January for three separate periods spreading over fourteen days. We found that the time-averaged continuum energy spectrum between 1 keV and 40 keV can be approximated with a spectral model composed of a direct power-law component, its reflection component, two warm absorbers with different ionization states, and neutral absorption. We have taken two approaches to study its spectral variation at various timescales. The first approach was to make intensity-sliced spectra, and to study any correlation between the intensity and the spectral shape. The second approach was to study spectral changes between the intervals when the source flux is above (“bright state”) and below (“faint state”) the average for fixed time-intervals. In both approaches, we found a clear correlation between the intensity in the 6–10 keV band and the spectral ratio of 0.5–3.0 keV$/$6.0–10 keV. Such a spectral variation requires a change of the apparent slope of the direct component, whereas the shape and intensity of the reflection component are invariable. The observed apparent spectral change is explained by the variation of the ionization degree of one of the two warm absorbers due to the intrinsic source luminosity variation. The current results suggest that the warm absorber has a critical role to explain the observed continuum spectral shape and the variation of MCG $-$6–30–15, which is essential to constrain the parameters of the putatively broadened iron line emission feature.
Tidal Mechanism as an Impossible Cause of the Observed Secular Increase of the Astronomical Unit
Authors: Itoh Yousuke
Published: March 2014

Krasinsky and Brumberg (2004, Celest. Mech. Dyn. Astron., 90, 267) reported a secular increase in the Astronomical Unit (AU) of 15 meters per century. Recently, Miura et al. (2009, PASJ, 61, 1247) proposed that angular-momentum transfer from the rotation of the Sun to the orbital motion of the solar-system planets may explain the observed increase of the AU. They assumed that the tidal effect between the planets and the Sun is the cause of this transfer. Here, we claim that a tidal effect cannot be a cause of this type of transfer to explain the increase of the AU.
Suzaku and XMM-Newton Observations of Diffuse X-Ray Emission from the Eastern Tip Region of the Carina Nebula
Authors: Ezoe Yuichiro , Hamaguchi Kenji , Gruendl Robert A. , Chu You-Hua , Petre Robert , Corcoran Michael F.
Published: March 2014

The eastern tip region of the Carina Nebula was observed with the Suzaku XIS for 77 ks to conduct a high-precision spectral study of extended X-ray emission. XMM-Newton EPIC data of this region were also utilized to detect point sources. The XIS detected strong extended X-ray emission from the entire field-of-view with a 0.2–5 keV flux of 0.7–4$\times$10$^{-14}$ergs$^{-1}$arcmin$^{-2}$. The emission has a blob-like structure that coincides with an ionized gas filament observed in mid-infrared images. Contributions of astrophysical backgrounds and the detected point sources were insignificant. Thus the emission is diffuse in nature. The X-ray spectrum of the diffuse emission was represented by a two-temperature plasma model with temperatures of 0.3 and 0.6 keV and an absorption column density of 2$\times$10$^{21}$cm$^{-1}$. The X-ray emission showed normal nitrogen-to-oxygen abundance ratios and a high iron-to-oxygen abundance ratio. The spectrally deduced parameters, such as temperatures and column densities, are common to the diffuse X-ray emission near $\eta$ Car. Thus, the diffuse X-ray emission in these two fields may have the same origin. The spectral fitting results are discussed to constrain the origin in the context of stellar winds and supernovae.
X-Ray Spectral Variability of the Seyfert Galaxy NGC 4051 Observed with Suzaku
Authors: Terashima Yuichi , Gallo Luigi C. , Inoue Hirohiko , Markowitz Alex G. , Reeves James N. , Anabuki Naohisa , Fabian Andrew C. , Griffiths Richard E. , Hayashida Kiyoshi , Itoh Takeshi , Kokubun Norihide , Kubota Aya , Miniutti Giovanni , Takahashi Tadayuki , Yamauchi Makoto , Yonetoku Daisuke
Published: March 2014

We report on results from a Suzaku observation of the narrow-line Seyfert 1 NGC 4051. During our observation, large-amplitude rapid variability was seen, and the averaged 2–10 keV flux was 8.1$\times$10$^{-12}$erg s$^{-1}$cm$^{-2}$ which is several times lower than the historical average. The X-ray spectrum hardens when the source flux becomes lower, confirming the trend of spectral variability known for many Seyfert 1 galaxies. The broad-band averaged spectrum and spectra in high- and low-flux intervals were analyzed. The spectra were first fitted with a model consisting of a power-law component, a reflection continuum originating in cold matter, a blackbody component, two zones of ionized absorber, and several Gaussian emission lines. The amount of reflection is rather large ($R$$\sim$ 7, where $R$$=$ 1 corresponds to reflection by an infinite slab), while the equivalent width of the Fe-K line at 6.4 keV is modest (140 eV) for the averaged spectrum. We then modeled the overall spectra by introducing partial covering for the power-law component and reflection continuum independently. The column density for the former is 1$\times$10$^{23}$cm$^{-2}$, while it is fixed at 1$\times$10$^{24}$cm$^{-2}$ for the latter. By comparing the spectra in different flux states, we could identify the causes of spectral variability.
Discoveries of 3 K-Shell Lines of Iron and a Coherent Pulsation of 593 s from SAX J1748.2$-$2808
Authors: Nobukawa Masayoshi , Koyama Katsuji , Matsumoto Hironori , Tsuru Takeshi Go
Published: March 2014

SAX J1748.2$-$2808 is a unique X-ray object with a flat spectrum and strong emission lines at 6.4–7.0 keV. The Suzaku satellite resolved the emission lines into 3 K-shell lines from neutral and highly ionized irons. A clear coherent pulsation with a period of 593 s was found from the Suzaku and XMM-Newton archives. These facts favor that SAX J1748.2$-$2808 is an intermediate polar, a subclass of a magnetized white dwarf binary (cataclysmic variable). This paper reports on details of the findings, and discusses the origin of this source.
Method of the Particle-in-Cell Simulation for the Y-Point in the Pulsar Magnetosphere
Authors: Umizaki Mitsuhiro , Shibata Shinpei
Published: March 2014

Recent observations in the X-ray and Gamma-ray suggest that the emission region of the pulsar magnetosphere can be multifold. In particular, the open-close boundary of the magnetic field, so-called the Y-point, can be a new candidate place where magnetic field energy converts into plasma heat and/or flow energy. Here, we present a new Particle-in-Cell code, which can be applied to the Y-point of the pulsar magnetosphere in axisymmetric geometry. The electromagnetic solver is used in two-dimensional grid points with cylindrical coordinates ($R$, $z$), while the particle solver operates in three-dimensional Cartesian coordinates ($x$, $y$, $z$), where the Buneman–Boris method is used. The particle motion is treated in special relativity. The inner boundary conditions are set up to generate rotation of the magnetosphere by use of the force-free semi-analytic solution given by Uzdensky (2003, ApJ, 598, 446). The code has been verified by dispersion relations of all wave modes in electron-positron plasmas. The initial test run is also presented to demonstrate the Y-shaped structure at the top of the dead zone on the light cylinder. We suggest that the structure is variable with quasi-periodicity with magnetic reconnection, and that plasma will be accelerated and/or heated. In a time-averaged point of view, the break up of the ideal-MHD (magneto-hydrodynamics) condition takes place in the vicinity of the Y-point.
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

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 $>$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.
Sensitivity Analysis of Optical Systems in Radio Telescopes
Authors: Sugimoto Masahiro , Iguchi Satoru , Inatani Junji , Sekimoto Yutaro , Asayama Shin’ichiro
Published: March 2014

We have demonstrated an approach to predict the overall efficiency and system noise regarding optical systems in radio telescopes, based on a systematic evaluation of both the optical propagation efficiency through all optical components, from the receiver horn to the main reflector, and of their noise contributions. The analysis employs several conventional techniques, including the principle of multimode Gaussian optics and calculations of losses associated with optical components. A detailed analysis was performed for cases of ALMA band 4 (125–163 GHz) and 8 (385–500 GHz). The analysis predicts a reasonable efficiency of 0.75–0.76 (0.57–0.62) and a system noise of $\sim$70 K (300–400 K) for band 4 (band 8). The calculated efficiency of the band 4 optics was found to be consistent with the efficiency measured by astronomical observations with the ALMA/ACA 12-m antenna. In addition to a confirmation that the bands 4 and 8 optics were designed to maximize the overall efficiency, the analysis for the bands 4 and 8 frequency ranges also confirmed that there is no difference in the optimum edge levels at the subreflector between the two different ways of maximization, i.e., toward the overall efficiency or the sensitivity, which is defined by the ratio of the overall efficiency over the sum of noises generated from all possible sources. We also applied a sensitivity analysis to the band 1 frequency case, and revealed a slight, but clear, difference in the optimum edge levels between the sensitivity and the efficiency (difference is 1–2 dB). This corresponds to a sensitivity loss of 1% if we optimize the optics to maximize the efficiency.
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

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

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

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

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

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 X-Ray and Optical Spectroscopic Observations of SS 433 in the 2006 April Multiwavelength Campaign
Authors: Kubota Kaori , Ueda Yoshihiro , Kawai Nobuyuki , Kotani Taro , Namiki Masaaki , Kinugasa Kenzo , Ozaki Shinobu , Iijima Takashi , Fabrika Sergei , Yuasa Takayuki , Yamada Shin’ya , Makishima Kazuo
Published: March 2014

We report on results of the 2006 April multiwavelength campaign of SS 433, focusing on X-ray data observed with Suzaku at two orbital phases (in- and out-of-eclipse phases) and on simultaneous optical spectroscopic observations. Analyzing the FeXXV K$\alpha$ lines originating from the jets, we detected a rapid variability of the Doppler shifts, $dz/dt \approx$ 0.019$/$0.33d$^{-1}$, which is larger than those expected from the precession and/or nodding motion. This phenomenon probably corresponds to “jitter” motions observed for the first time in X-rays, for which significant variabilities in both the jet angle and the intrinsic speed are required. From time lags between optical Doppler curves and X-ray ones, we estimated a distance between the optical jets and the base to be $\sim$(3-4) $\times$ 10$^{14}$cm. Based on the radiatively cooling jet model, we determined that the innermost temperatures of the jets are $T_0 =$ 13$\pm$2keV for the out-of-eclipse phase and 16$\pm$3keV for the in-eclipse (the average of the blue and red jets) from the line intensity ratio of FeXXV K$\alpha$ and FeXXVI K$\alpha$. While the broad-band-continuum spectra over the 5-40keV band in eclipse is consistent with a multitemperature-bremsstrahlung emission expected from the jets and its reflection component from cold matter, the out-of-eclipse spectrum is harder than the jet emission with the base temperature determined above, implying the presence of an additional hard component.
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

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 $> $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

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.
Forecast for Phoenicids in 2008, 2014, and 2019
Authors: Sato Mikiya , Watanabe Jun-ichi
Published: March 2014

We report here on a complete forecast of the activity of future Phoenicid meteor showers in the period 2008–2020. We detail predictions of Phoenicids activities during three years: 2008, 2014, and 2019. In 2008, the trail of 1866 will intersect with the Earth orbit. In 2014, the origin of the activity will be due to several trails formed from the 19th to the early 20th centuries. The display in 2014 will be the most spectacular meteor showers among the three cases because of a favorable geometric condition. In 2019, the Earth will approach four trails formed between 1872 and 1882, and one trail of 1946. Since the parent body had not been observed during the above-mentioned period, the activity of these meteor showers is important for estimating the degree of cometary activity for this parent body during this period.
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

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

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

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

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.
Additional Acceleration of Protons and Energetic Neutrino Production in a Filamentary Jet of the Blazar Markarian 501
Authors: Honda Yasuko S. , Honda Mitsuru
Published: March 2014

Blazars have been regarded as one of the most powerful sources of the highest energy cosmic rays and also their byproducts, neutrinos. Provided that a magnetized filamentary system is established in a blazar jet as well, we could apply the mechanism of multi-stage diffusive shock acceleration to a feasible TeV emitter, Mrk 501 to evaluate the achievable maximum energy of protons. Taking conceivable energy restriction into account systematically, it seems adequate to say that EeV-protons are produced at this site by our present model. We also estimate neutrino fluxes generated by these accelerated protons, and discuss the detectability based on an updated kilometer-scale telescope, such as IceCube.
LoCuSS: Subaru Weak Lensing Study of 30 Galaxy Clusters
Authors: Okabe Nobuhiro , Takada Masahiro , Umetsu Keiichi , Futamase Toshifumi , Smith Graham P.
Published: March 2014

We use high-quality Subaru/Suprime-Cam imaging data to conduct a detailed weak lensing study of the distribution of dark matter in a sample of 30 X-ray luminous galaxy clusters at 0.15 $\le z \le$ 0.3. A weak lensing signal is detected at high statistical significance in each cluster, the total signal-to-noise ratio of the detections ranging from 5 to 13. Comparing spherical models to the tangential distortion profiles of the clusters individually, we are unable to discriminate statistically between a singular isothermal sphere (SIS) and Navarro, Frenk, and White (NFW) models. However, when the tangential distortion profiles are combined and then models are fitted to the stacked profile, the SIS model is rejected at 6$\ \sigma$ and 11$\ \sigma$, respectively, for low ($M_{\rm vir}\lt$ 6 $\times$ 10$^{14}\ h^{-1}\ M_\odot$) and high ($M_{\rm vir} \gt $ 6 $\times$ 10$^{14}\ h^{-1}\ M_\odot$) mass bins. We also used individual cluster NFW model fits to investigate the relationship between the cluster mass and the concentration, finding that the concentration ($c_{\rm vir}$) decreases with increasing cluster mass ($M_{\rm vir}$). The best-fit $c_{\rm vir}$–$M_{\rm vir}$ relation is: $c_{\rm vir}$($M_{\rm vir}$) $=$ 8.75$^{+4.13}_{-2.89} \times$ ($M_{\rm vir}/$10$^{14}\ h^{-1}\ M_\odot$)$^{-\alpha}$ with $\alpha \approx$ 0.40$\ \pm\ $0.19: i.e., a non-zero slope is detected at 2$\ \sigma$ significance. This relation gives a concentration of $c_{\rm vir} =$ 3.48$^{+1.65}_{-1.15}$ for clusters with $M_{\rm vir} =$ 10$^{15}\ h^{-1}M_\odot$, which is inconsistent at 4$\ \sigma$ significance with the values of $c_{\rm vir} \sim$ 10 reported for strong-lensing-selected clusters. We have found that the measurement error on the cluster mass is smaller at higher over-densities, $\Delta \simeq$ 500–2000, than at the virial over-density, $\Delta_{\rm vir} \simeq$ 110; typical fractional errors at $\Delta \simeq$ 500–2000 are improved to $\ \sigma$($M_\Delta$)$/M_{\Delta } \simeq$ 0.1–0.2 compared with 0.2–0.3 at $\Delta_{\rm vir}$. Furthermore, comparing the 3D spherical mass with the 2D cylinder mass, obtained from the aperture mass method at a given aperture radius, $\theta_\Delta$, reveals $M_{\rm 2D}$($\lt \theta_{\Delta}$)$/M_{\rm 3D}$($\lt r_\Delta = D_{\rm l}\theta_{\Delta}$) $\simeq$ 1.46 and 1.32 for $\Delta =$ 500 and $\Delta_{\rm vir}$, respectively. The amplitude of this offset agrees well with that predicted by integrating an NFW model of cluster-scale halos along the line-of-sight.
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

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

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

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

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

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.
A Search for Water Masers in the Saturnian System
Authors: Takahashi Shigeru , Deguchi Shuji , Kuno Nario , Shimoikura Tomomi , Yoshida Fumi
Published: March 2014

We have searched for H$_{2}$O 6(1,6)–5(2,3) maser emission at 22.235 GHz from several Saturnian satellites with the Nobeyama 45 m radio telescope in 2009 May. Objects of our observation are Titan, Hyperion, Enceladus, and Atlas, from which Pogrebenko et al. (2009, A&A, 494, L1) reported having detected water masers at 22.235 GHz, and in addition are Iapetus and other inner satellites. We detected no emission of the water-maser line from all of the satellites observed, although the sensitivities of our observation are comparable to, or even better than, those of Pogrebenko et al. (2009, A&A, 494, L1). We infer from our observation that the water-maser emission from the Saturnian system is extremely weak, or sporadic in itself. Both monitoring over a long period and obtaining statistical results are important for gaining a further understanding of the water-maser emission in the Saturnian system.
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

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.
Variation of Molecular Gas Properties Across the Spiral Arms in IC 342: Large-Scale 13CO (1–0) Emission
Authors: Hirota Akihiko , Kuno Nario , Sato Naoko , Nakanishi Hiroyuki , Tosaki Tomoka , Sorai Kazuo
Published: March 2014

We present a $^{13}$CO (1–0) mapping survey of the nearby galaxy IC 342 carried out with the Nobeyama 45 m radio telescope. The map covers a 320$^{\prime\prime} \times$ 320$^{\prime\prime}$ region, including its center, bar, and most of one of the spiral arms. The $^{13}$CO (1–0) data were compared with $^{12}$CO (1–0), H$\alpha$, 24$\ \mu$m, and $K_{\rm s}$-band images to investigate spatial relations among molecular clouds, star-forming regions, and the stellar potential. The line ratio between both CO lines, $I$[$^{13}$CO (1–0)]$/I$[$^{12}$CO (1–0)] $\equiv R_{13/12}$, was also derived to investigate the variation of molecular gas properties. The mean value of $R_{13/12}$ in the center of IC 342 is low ($\sim\ $0.10$\ \pm\ $0.01) compared to the disk region ($\sim\ $0.15$\ \pm\ $0.01). While $R_{13/12}$ in the central region is rather uniform, significant variations of $R_{13/12}$ were found in the spiral arms; that is, while it is low ($\sim\ $0.1) at both ends of the bar and at the giant molecular cloud association (GMA) found in the spiral arm, it is high (0.14–0.20) downstream from the low $R_{13/12}$ region. The low- and high-$R_{13/12}$ regions in the disk correspond to the $^{12}$CO peak and star-forming regions, respectively. The low $R_{13/12}$ in the galactic center is likely due to the higher gas temperature in the starburst region. The most probable explanation of the $R_{13/12}$ variation in the disk is that a low $R_{13/12}$ in the GMA and the ends of the bar reflects an increased fraction of the diffuse molecular component, which has a low column density and low volume density. Around the GMA and the north end of the bar, not only are the star-forming regions downstream from the CO distributions, but $R_{13/12}$ is also higher downstream, implying the presence of gas compression and ionized/molecular gas spatial offsets, as predicted by density wave models.
A Catalog of Suzaku/WAM Hard X-Ray Solar Flares
Authors: Endo Akira , Minoshima Takashi , Morigami Kouichi , Suzuki Masanobu , Shimamori Atsushi , Sato Yumi , Terada Yukikatsu , Tashiro Makoto S. , Urata Yuji , Sonoda Eri , Yamaoka Kazutaka , Sugita Satoshi , Watanabe Kyoko
Published: March 2014

We developed a catalog of solar flares in the hard X-ray band observed with the Wide-band All-sky Monitor (WAM) onboard the Suzaku satellite between 2005 July and 2009 November. During this period, 105 solar flares (GOES class X: 13, M: 29, C: 47, B: 16) were detected with WAM, including 10% of GOES-class C events reported during the same period. The observed photon flux ranged between 9 $\times$ 10$^{-5}$ and 9 $\times$ 10$^{-1}\ $photons s$^{-1}\ $cm$^{-2}\ $keV$^{-1}\ $ at 100 keV. The averaged hard X-ray spectrum for each solar flare was evaluated for 70 of the 105 events, and 43 of them were well fitted with a single power-law model with a photon index ranging between $-$7 and $-$3. We observed a weak trend where events with longer durations exhibited harder spectral slopes.
MAXI GSC Observations of a Spectral State Transition in the Black Hole Candidate XTE J1752–223
Authors: Nakahira Satoshi , Yamaoka Kazutaka , Sugizaki Mutsumi , Ueda Yoshihiro , Negoro Hitoshi , Ebisawa Ken , Kawai Nobuyuki , Matsuoka Masaru , Tsunemi Hiroshi , Daikyuji Arata , Eguchi Satoshi , Hiroi Kazuo , Ishikawa Ryoji , Ishiwata Masaki , Isobe Naoki , Kawasaki Kazuyoshi , Kimura Masashi , Kohama Mitsuhiro , Mihara Tatehiro , Miyoshi Sho , Morii Mikio , Nakagawa Yujin E. , Nakajima Motoki , Ozawa Hiroshi , Sootome Tetsuya , Sugimori Kousuke , Suzuki Motoko , Tomida Hiroshi , Ueno Shiro , Yamamoto Takayuki , Yoshida Atsumasa ,   team the MAXI
Published: March 2014

We present the first results on the black-hole candidate XTE J1752$-$223 from the Gas Slit Camera (GSC) aboard the Monitor of All-sky X-ray Image (MAXI) on the International Space Station. Including the onset of an outburst reported by the Proportional Counter Array aboard the Rossi X-ray Timing Explorer on 2009 October 23, MAXI / GSC has been monitoring this source approximately 10 times per day with high sensitivity in the 2–20 keV band. XTE J1752$-$223 was initially in a low / hard state during the first 3 months. An anti-correlated behavior between the 2–4 keV and 4–20 keV bands was observed around 2010 January 20, indicating that the source exhibited a spectral transition to the high / soft state. A transient radio jet may have been ejected when the source was in the intermediate state where the spectrum was roughly explained by a power-law with a photon index of 2.5–3.0. The unusually long period in the initial low / hard state implies a slow variation in the mass-accretion rate, and a dramatic soft X-ray increase may be explained by a sudden appearance of the accretion disk component with a relatively low innermost temperature (0.4–0.7 keV). Such a low temperature might suggest that the maximum accretion rate was just above the critical gas-evaporation rate required for the state transition.
Early Spectroscopy of the 2010 Outburst of U Scorpii
Authors: Yamanaka Masayuki , Uemura Makoto , Kawabata Koji S. , Fujii Mitsugu , Tanabe Kenji , Imamura Kazuyoshi , Komatsu Tomoyuki , Arai Akira , Sasada Mahito , Itoh Ryosuke , Harao Tatsuya , Kunitomi Nanae , Nagae Osamu , Nose Mikiha , Ohsugi Takashi , Okushima Takako , Sakimoto Kiyoshi , Yoshida Michitoshi
Published: March 2014

We present early spectroscopy of the recurrent nova U Sco during an outburst in 2010. We successfully obtained time-series spectra during the period of $t_{\rm d} =$ 0.37–0.44 d, where $t_{\rm d}$ is the time that elapsed since the discovery of the present outburst. This is the first time-resolved spectroscopy on the first night of U Sco outbursts. At $t_{\rm d} \sim$ 0.4 d, the H$\alpha$ line consists of a blue-shifted ($-$5000 km s$^{-1}$) narrow absorption component and a wide, triple-peak emission one: blue ($\sim-$3000 km s$^{-1}$), central ($\sim$0 km s$^{-1}$), and red ($\sim+$3000 km s$^{-1}$) peaks. The blue and red peaks developed more rapidly than the central one for the first night. This rapid variation would be caused by the growth of aspherical wind produced during the earliest stage of the outburst. At $t_{\rm d} =$ 1.4 d, the H$\alpha$ line has a nearly flat-topped profile with weak blue and red peaks at $\sim \pm$3000 km s$^{-1}$. This profile can be attributed to a nearly spherical shell, while the asphericity growing on the first night still remains. The wind asphericity is less significant after $t_{\rm d} =$ 9 d.
A Novel Jet Model: Magnetically Collimated, Radiation-Pressure Driven Jet
Authors: Takeuchi Shun , Ohsuga Ken , Mineshige Shin
Published: March 2014

Relativistic jets from compact objects are ubiquitous phenomena in the Unvierse, but their driving mechanism has been an enigmatic issue for several decades. Two basic models have been extensively discussed: magnetohydrodynamic (MHD) jets and radiation-hydrodynamic (RHD) jets. Currently, the former is more widely accepted, since the magnetic field is expected to provide both acceleration and collimation mechanisms, whereas the radiation field cannot collimate the outflow. Here, we propose a new type of jets, radiation-magnetohydrodynamic (RMHD) jets, based on our global RMHD simulation of luminous accretion flows onto a black hole shining above the Eddington luminosity. The RMHD jet can be accelerated up to relativistic speed by the radiation-pressure force and collimated by the Lorentz force of a magnetic tower structure inflated by toroidal magnetic field lines accumulated around the black hole, though the radiation energy greatly dominates over the magnetic energy. This magnetic tower is collimated by a geometrically thick accretion flow supported by a radiation-pressure force. This type of jet may explain relativistic jets from Galactic microquasars, appearing at high luminosity.