bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Variable Partial Covering Model for the Seyfert 1 Galaxy MCG −6–30–15
Authors: Miyakawa Takehiro , Ebisawa Ken , Inoue Hajime 
Published: March 2014

AbstractWe propose a simple spectral model for the Seyfert 1 Galaxy MCG $-$ 6–30–15 that can explain most of the 1–40 keV spectral variation by a change of the partial covering fraction, similar to that proposed by Miller, Turner, and Reeves (2008, A&A, 483, 437). Our spectral model is composed of three continuum components: (1) a direct power-law component, (2) a heavily absorbed power-law component by mildly ionized intervening matter, and (3) a cold-disk reflection component far from the black hole with a moderate solid-angle ($ \Omega/$ 2$ \pi$$ \simeq$ 0.3) accompanying a narrow fluorescent iron line. The first two components are affected by the surrounding thin highly ionized absorber with $ N_{\rm H}$$ \simeq$ 10$ ^{23.4}$ cm$ ^{-2}$ and log $ \xi$$ \simeq$ 3.4. The heavy absorber in the second component is fragmented into many clouds, each of which is composed of radial zones with different ionization states and different column densities, a main body ($ N_{\rm H}$$ \simeq$ 10$ ^{24.2}$ cm$ ^{-2}$ , log $ \xi$$ \simeq$ 1.6), an envelope ($ N_{\rm H}$$ \simeq$ 10$ ^{22.1}$ cm$ ^{-2}$ , log $ \xi$$ \simeq$ 1.9), and presumably a completely opaque core. Not only the intrinsic spectral shape of the X-ray source but also these parameters of the ionized absorbers are unchanged at all. The central X-ray source extends moderately, and its luminosity is not significantly variable. The observed flux and spectral variations are mostly explained by the variation of the geometrical partial covering fraction of the central source ranging from 0 (uncovered) to $ \sim\ $ 0.63 by the intervening ionized clouds in the line of sight. The ionized iron K-edge of the heavily absorbed component explains most of the seemingly broad line-like features, a well-known spectral characteristic of MCG $-$ 6–30–15. The direct component and the absorbed one are negatively correlated, and their variations cancel out each other, so that the fractional spectral variation becomes the minimum at the iron-energy band; thus, another observational characteristic of MCG $-$ 6–30–15 is explained.
Pilot VLBI Survey of SiO v = 3 J = 1 → 0 Maser Emission around Evolved Stars
Authors: Imai Hiroshi , Oyadomari Miyako , Chong Sze Ning , Nakagawa Akiharu , Kurayama Tomoharu , Nakashima Jun-ichi , Matsumoto Naoko , Nagayama Takumi , Oyama Tomoaki , Mizuno Shota , Deguchi Shuji , Cho Se-Hyung 
Published: March 2014

Abstract
In this letter, we report on detections of SiO $ v$ $ =$ 3 $ J$ $ =$ 1$ \rightarrow$ 0 maser emission in very long-baseline interferometric (VLBI) observations towards 4 out of 12 long-period variable stars: WX Psc, R Leo, W Hya, and T Cep. The detections towards WX Psc and T Cep are new ones. We also present successful astrometric observations of SiO $ v$ $ =$ 2 and $ v$ $ =$ 3 $ J$ $ =$ 1$ \rightarrow$ 0 maser emissions associated with two stars: WX Psc and W Hya and their position-reference continuum sources: J010746.0$ +$ 131205 and J135146.8$-$ 291218 with the VLBI Exploration of Radio Astrometry (VERA). The relative coordinates of the position-reference continuum source and SiO $ v$ $ =$ 3 maser spots were measured with respect to those of an SiO $ v$ $ =$ 2 maser spot adopted as a fringe-phase reference. Thus, the faint continuum sources were inversely phase-referenced to the bright maser sources. This implies possible registration of multiple SiO maser line maps onto a common coordinate system with 10 microarcsecond-level accuracy.
A Study of the Long-Term Spectral Variations of 3C 66A Observed with the Fermi and Kanata Telescopes
Authors: Itoh Ryosuke , Fukazawa Yasushi , Chiang James , Hanabata Yoshitaka , Hayashida Masaaki , Hayashi Katsuhiro , Mizuno Tsunefumi , Ohno Masanori , Ohsugi Takashi , Perkins Jeremy S. , Rainò Silvia , Reyes Luis C. , Takahashi Hiromitsu , Tanaka Yasuyuki , Tosti Gino , Akitaya Hiroshiv , Arai Akira , Kino Masaru , Ikejiri Yuki , Kawabata Koji S. , Komatsu Tomoyuki , Sakimoto Kiyoshi , Sasada Mahito , Sato Shuji , Uemura Makoto , Ui Takahiro , Yamanaka Masayuki , Yoshida Michitoshi 
Published: March 2014

Abstract
3C 66A is an intermediate-frequency-peaked BL Lac object detected by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. We present a study of the long-term variations of this blazar seen over ∼ 2 yr at GeV energies with Fermi and in the optical (flux and polarization) and near infrared with the Kanata telescope. In 2008, the first year of the study, we find a correlation between the gamma-ray flux and the measurements taken with the Kanata telescope. This is in contrast to the later measurements performed during 2009–2010 which show only a weak correlation along with a gradual increase of the optical flux. We calculate an external seed photon energy density assuming that the gamma-ray emission is due to external Compton scattering. The energy density of the external photons is found to be higher by a factor of two in 2008 compared to 2009–2010. We conclude that the different behaviors observed between the first year and the later years might be explained by postulating two different emission components.
Identifying Subclasses of Long Gamma-Ray Bursts with Cumulative Light-Curve Morphology of Prompt Emissions
Authors: Tsutsui Ryo , Nakamura Takashi , Yonetoku Daisuke , Takahashi Keitaro , Morihara Yoshiyuki 
Published: March 2014

Abstract
We argue for a new classification scheme of long gamma-ray bursts (LGRBs) using the morphology of the cumulative light curve of prompt emission. We parametrize the morphology by an absolute deviation from their constant luminosity (ADCL), and derive the value for 36 LGRBs that have spectropic redshifts, spectral parameters determined by the Band model, 1-s peak fluxes, fluences, and 64-ms resolution light curves whose peak counts are 10-times larger than background fluctuations. Based on a possible bimodal distribution of the value of ADCL, we divide the sample into two groups (ADCL $ &lt;$ 0.17 and ADCL $ &gt;$ 0.17), and for each group derive the spectral peak energy $ E_{\rm p}$ –peak luminosity $ L_{\rm p}$ correlation and the Fundamental Plane of LGRBs, which is a correlation between $ E_{\rm p}$ , the luminosity time $ T_{\rm L}$ ($ \equiv$ $ E_{\rm iso}/L_{\rm p}$ where $ E_{\rm iso}$ is isotropic energy), and $ L_{\rm p}$ . We find that the Fundamental Plane at $ E_{\rm p}$ $ =$ 10$ ^{2.71}$ keV and $ T_{\rm L}$ $ =$ 10$ ^{0.86}$ s for large ADCL events are 2.8-times brighter than that for small ADCL events with 5-$ \sigma$ levels. The Fundamental Planes with small and large ADCL are given by $ L_{\rm p}$ $ =$ 10$ ^{52.53\pm 0.01}$ ($ E_{\rm p}/$ 10$ ^{2.71}$ keV)$ ^{1.84\pm 0.03}$ ($ T_{\rm L}/$ 10$ ^{0.86}$ s)$ ^{0.29\pm0.08}$ with $ \chi^2_{\nu}$ $ =$ 10.93$ /$ 14 and $ L_{\rm p}$ $ =$ 10$ ^{52.98\pm0.08}$ ($ E_{\rm p}/$ 10$ ^{2.71}$ keV)$ ^{1.82\pm 0.09}$ ($ T_{\rm L}/$ 10$ ^{0.86}$ s)$ ^{0.85\pm 0.27}$ with $ \chi^2_{\nu}$ $ =$ 7.58$ /$ 8, respectively. This fact implies the existence of subclasses of LGRBs characterized by the value of ADCL. The other significant difference between the relations for the two subclasses consists in the exponent of $ T_{\rm L}$ , which might provide a hint of the physics of the relations, but the significance is now only at 2-$ \sigma$ levels. Also, there is a hint for the existence of an intermediate-ADCL class, which deviates from both fundamental planes. Both relations are so tight that our result provides a new accurate distance measurement scheme up to the high-redshift universe.
Spatially Resolved Near-Infrared Imaging of a Gravitationally Lensed Quasar, APM 08279+5255, with Adaptive Optics on the Subaru Telescope
Authors: Oya Shin , Minowa Yosuke , Terada Hiroshi , Watanabe Makoto , Hattori Masayuki , Hayano Yutaka , Saito Yoshihiko , Ito Meguru , Pyo Tae-Soo , Takami Hideki , Iye Masanori 
Published: March 2014

Abstract
We present a spatially resolved imaging analysis of a three-component gravitationally lensed quasar at $ z$ $ =$ 3.91, APM 08279$ +$ 5255, in the $ L'$- and $ M'$-bands, and a narrow band centered at 3.05 $ \mu$ m using the 188-element adaptive optics system on the Subaru Telescope. The third, faintest quasar image, component C, has been clearly resolved in all of these bands for the first time. All of the three components are point sources in all three bands. No new component, neither a fourth quasar image nor a lens galaxy, was discovered. The observed bands correspond to the long-wavelength end of the optical power-law continuum of the source quasar in its rest frame, and are little contaminated by strong emission lines like H$ \alpha$ . The measured flux ratio of components C to B is shown to be constant in all of the observed bands, and its achromatic nature agrees well with preceding work done at short near-infrared wavelengths one decade ago. On the other hand, the flux ratio of components A to B shows an increase from that of past measurements. This could be ascribed to a microlensing event.
IRSF SIRIUS JHKs Simultaneous Transit Photometry of GJ 1214b
Authors: Narita Norio , Nagayama Takahiro , Suenaga Takuya , Fukui Akihiko , Ikoma Masahiro , Nakajima Yasushi , Nishiyama Shogo , Tamura Motohide 
Published: March 2014

Abstract
We report on the high-precision transit photometry of GJ 1214b in JHK$ _{\rm s}$ bands simultaneously taken with the SIRIUS camera on the Infrared Survey Facility 1.4 m telescope located in Sutherland, South Africa. Our Markov-Chain Monte Carlo analysis shows that observed planet-to-star radius ratios in the JHK$ _{\rm s}$ bands are $ R_{\rm p}/R_{{\rm s},J}$$ =$ 0.11833 $ \pm$ 0.00077, $ R_{\rm p}/R_{{\rm s},H}$$ =$ 0.11522 $ \pm$ 0.00079, and $ R_{\rm p}/R_{{\rm s},K_{\rm s}}$$ =$ 0.11459 $ \pm$ 0.00099, respectively. The radius ratios are very consistent with previous studies by Bean et al. (2011, ApJ, 743, 92) within 1 $ \sigma$ , while our ratio in the K$ _{\rm s}$ band is shallower than previous measurements in the same band by Croll et al. (2011, ApJ, 736, 78) and inconsistent even at the 4 $ \sigma$ level with them. We have no satisfactory explanation for this discrepancy at this point. Our overall results support a flat transmission spectrum in the observed bands, which can be explained by a water-dominated atmosphere or an atmosphere with extensive high-altitude clouds or haze. To explain the discrepancy of the radius ratios, and to determine a definitive atmosphere model for GJ 1214b in the future, more extended transit observations in around the K$ _{\rm s}$ band would be especially important.
Annual Parallax Distance and Secular Motion of the Water Fountain Source IRAS 18286–0959
Authors: Imai Hiroshi , Kurayama Tomoharu , Honma Mareki , Miyaji Takeshi 
Published: March 2014

Abstract
We report on results of astrometric observations of H$ _{2}$ O masers in the ``water fountain'' source IRAS 18286$-$ 0959 (I18286) with the VLBI Exploration of Radio Astrometry (VERA). These observations yielded an annual parallax of IRAS 18286$-$ 0959, $ \pi$ $ =$ 0.277 $ \pm$ 0.041 mas, corresponding to a heliocentric distance of $ D$ $ =$ 3.61$ ^{+0.63}_{-0.47}$ kpc. The maser feature, whose annual parallax was measured, showed an absolute proper motion of ($ \mu_{\alpha}$ , $ \mu_{\delta}$ ) $ =$ ($-$ 3.2 $ \pm$ 0.3, $-$ 7.2 $ \pm$ 0.2) [mas yr$ ^{-1}$ ]. The intrinsic motion of the maser feature in the internal motions of the cluster of features in I18286 does not seem to trace the motion of the bipolar jet of I18286. Taking into account this intrinsic motion, the derived motion of the maser feature is roughly equal to that of the maser source I18286 itself. The proximity of I18286 to the Galactic midplane ($ z$ $ \approx$ 10 pc) suggests that the parental star of the water fountain source in I18286 should be an intermediate-mass AGB/post-AGB star, but the origin of a large deviation of the systemic source motion from that expected from the Galactic rotation curve is still unclear.
Photopolarimetric Monitoring of the Blazar BL Lac in the Optical and Near-Infrared Bands: Decay of the Long-Lived Component
Authors: Sakimoto Kiyoshi , Uemura Makoto , Sasada Mahito , Kawabata Koji S. , Fukazawa Yasushi , Yamanaka Masayuki , Itoh Ryosuke , Ohsugi Takashi , Yoshida Michitoshi , Akitaya Hiroshi , Sato Shuji , Kino Masaru 
Published: March 2014

Abstract
We report on the results of optical–near-infrared photopolarimetric observations of BL Lac conducted from 2008 to 2011. Our observations are consistent with past studies in which the behavior of the polarization of BL Lac could be understood with two components: short flares whose polarization angles randomly change, and a long-lived component. In addition, we detected a gradually decreasing trend in the total flux, the polarized flux, and the polarization degree without a large variation in the polarization angle from 2008 to mid-2009. These results suggest that the long-lived component decayed from 2008 to mid-2009. We propose that the long-lived component is not stationary, but is probably variable with a time-scale of years. We found no change in the activity of the short flares in 2008 and 2009, when the long-lived component was strong and weak, respectively. Furthermore, there were no clear differences in the mean color and the distribution of the polarization angle of the short flares from 2008 to 2009. These facts indicate that the emitting region of the long-term component was physically disconnected to that of the short flares. The color of the long-term component was bluer than that of the short flares, indicating a higher synchrotron peak-frequency. This could be due to a low efficiency of synchrotron and/or Compton cooling in the emitting region of the long-lived component. The long-term component is possibly originated from a relatively downstream region in the jet where the electron density is low, or the external radiation field is weak.
Modeling Line-Driven Disk Wind for Broad Absorption Lines of Quasars
Authors: Nomura Mariko , Ohsuga Ken , Wada Keiichi , Susa Hajime , Misawa Toru 
Published: March 2014

Abstract
The disk wind, which is powered by the radiation force due to spectral lines (line force), has been studied concerning broad absorption line (BAL) quasars. We investigated the structure of the disk wind based on a non-hydrodynamic method, and compared it with wind properties inferred from X-ray observations of BAL quasars. In the present work, we applied the stellar wind theory to the initial condition (the mass outflow rate at the base of the wind). We found funnel-shaped winds with a half opening angle of $ \sim$ 50$ ^{\circ}$ for the case of $ \epsilon$$ =$ 0.3–0.9 and $ M_{\rm BH}$$ =$ 10$ ^{7-8.5}$$ M_\odot$ , where $ \epsilon$ is the Eddington ratio and $ M_{\rm BH}$ is the black-hole mass. Thus, the absorption features are observed for an observer of which the viewing angle is around 50$ ^{\circ}$ . A probability of BAL quasars is $ \sim$ 7%–11%, which is roughly consistent the abundance ratio of BAL quasars, $ \sim$ 10%–15%. Here, the probability is estimated by the solid angle, that the absorbing features would be detected, divided by 4$ \pi$ . In contrast, if the Eddington ratio is smaller than 0.01, or if the black hole is very massive, $ M_{\rm BH}$$ \gtrsim$ 10$ ^{9}$$ M_{\odot}$ , the disk wind is not launched due to the less effective line force. Then, the quasars are identified as non-BAL quasars independently of the observer's viewing angle.
Two Power-Law States of the Ultraluminous X-Ray Source IC 342 X-1
Authors: yoshida Tessei , isobe Naoki , mineshige Shin , kubota Aya , mizuno Tsunefumi , saitou Kei 
Published: March 2014

Abstract
In order to elucidate the emission properties of ultraluminous X-ray sources (ULXs) during their power-law (PL) state, we examined long-term X-ray spectral data of IC 342 X-1 during its PL state by using our own Suzaku data and archival data by XMM-Newton, Chandra, and Swift observations. The PL state of this source seems to be classified into two sub-states in terms of the X-ray luminosities in the 0.5–10 keV band: the low-luminosity PL state with (4–6) $ \times$ 10$ ^{39}$ erg s$ ^{-1}$ and the high-luminosity one with (1.1–1.4) $ \times$ 10$ ^{40}$ erg s$ ^{-1}$ . During Suzaku observations, which were made in 2010 August and 2011 March, X-1 stayed in the low-luminosity PL state. The observed X-ray luminosity (4.9–5.6 $ \times$ 10$ ^{39}$ erg s$ ^{-1}$ ) and the spectral shape (photon index $ =$ 1.67–1.83) slightly changed between the two observations. Using the Suzaku PIN detector, we for the first time confirmed a PL tail extending up to at least 20 keV with no signatures of a high-energy turnover in both of the Suzaku observations. In contrast, a turnover at about 6 keV was observed during the high-luminosity PL state in 2004 and 2005 with XMM-Newton. Importantly, the photon indices are similar between the two PL states, and so are the Compton $ y$-parameters of $ y$$ \sim$ 1, which indicates a similar energy balance (between the corona and the accretion disk) holding in the two PL states despite different electron temperatures. From spectral similarities with recent studies about other ULXs, and the Galactic black-hole binary GRS 1915$ +$ 105, IC 342 X-1 is also likely to be in a state with a supercritical accretion rate, although more sensitive higher energy observations would be necessary to make any conclusion.
Suzaku Follow-Up Observation of the Activated Magnetar 1E 1547.0 5408
Authors: Iwahashi Takanori , Enoto Teruaki , Yamada Shin'ya , Nishioka Hiroyuki , Nakazawa Kazuhiro , Tamagawa Toru , Makishima Kazuo 
Published: March 2014

Abstract
We present broadband X-ray analyses of the magnetar 1E 1547.0$-$ 5408 observed with Suzaku on 2010 August 7, nearly one and a half years after an intense outburst in 2009 January. The 2–10 keV flux decreased to (1.06 $ \pm$ 0.01) $ \times$ 10$ ^{-11}$ erg cm$ ^{-2}$ s$ ^{-1}$ , while the hard X-ray detection was 3.5 $ \sigma$ (18–40 keV) and 2.4 $ \sigma$ (18–35 keV) significance levels, where the former includes only the 2% systematic error of the non X-ray background, and the latter further takes into account possible near-by contaminating sources, respectively. Our confirmation of both soft and hard X-ray components during the late phase of the outburst strengthened the possibility that most magnetars are composed of the two spectral components, both in burst-active and less-active states. Together with a similar decay speed between the soft and hard components, their radiation mechanisms are suggested to be tightly related to each other. The 1–40 keV broadband spectrum was successfully fitted with the same model as used in the fit just after the onset of the outburst in 2009: a surface blackbody radiation with photoelectric absorption and a hard power-law. The blackbody flux decreased to be $ \sim$ 30% of that in 2009 while keeping its temperature at $ kT$$ =$ 0.65 keV, suggesting a shrinking hotspot on the magnetar surface by a factor of 0.3. The hard power-law extended up to at least $ \sim$ 35 keV with a photon index of $ \Gamma$$ =$ 1.1 $ \pm$ 0.4, which was consistent with the 2009 value. The flux ratio, $ \xi$ , of the 1–60 keV power-law to 1–60 keV thermal component was calculated to be $ \xi$$ =$ 1.2 $ \pm$ 0.7 at the late phase of the outburst for the first time. The obtained $ \xi$ value follows the previously known negative correlation with the characteristic age, implying that the correlation holds for most of the magnetar states: no burst, onset and late phase of outbursts.
A Method to Estimate the Masses of Asymptotic Giant Branch Variable Stars
Authors: Takeuti Mine , Nakagawa Akiharu , Kurayama Tomoharu , Honma Mareki 
Published: March 2014

Abstract
AGB variable stars are at the transient phase between low and high mass-loss rates; estimating the masses of these stars is necessary to study the evolutionary processes and mass-loss processes during the AGB stage. We applied the pulsation constant theoretically derived by Xiong and Deng (2007 MNRAS, 378, 1270) to 15 galactic AGB stars in order to estimate their masses. We found that using the pulsation constant is effective to estimate the mass of a star pulsating with two different pulsation modes, such as S Crt and RX Boo, which provides mass estimates comparable to theoretical results of AGB star evolution. We also extended the use of the pulsation constant to single-mode variables, and analyzed the properties of AGB stars related to their masses.
κH-Mechanism of a Solar Eruption Produced Self-Consistently by Flux Emergence
Authors: Magara Tetsuya 
Published: March 2014

Abstract
We report on a new magnetohydrodynamic simulation for the sequence evolution of a magnetic field from emergence to eruption on the Sun. The magnetic field in the shape of a twisted flux tube emerging below the solar surface forms a pre-eruptive structure in the corona, which is composed of expanding envelop flux and a quasi-static inner core called flux rope; this inner core eventually seems to erupt. The evolution proceeds self-consistently; that is, any preexisting coronal magnetic field that causes additional side effects on the evolution of the emerging magnetic field is not assumed. This highlights a possible eruption mechanism inherent in the dynamic nature of the emerging magnetic field. The mechanism is characterized by two key quantities: the curvature ($ \kappa$ ) and the scale height ($ H$ ) of the emerging magnetic field.
Kinetic Scheme for Solving the M1 Model of Radiative Transfer
Authors: Kanno Yuji , Harada Tetsuya , Hanawa Tomoyuki 
Published: March 2014

Abstract
We show a numerical scheme to solve the moment equations of radiative transfer, i.e., the M1 model, which follows the evolution of the energy density, $E$, and the energy flux, $\boldsymbol{F}$. In our scheme we reconstruct the intensity from $E$ and $\boldsymbol{F}$, so that it is consistent with the closure relation, $\chi = \left(3+4f^2\right)/\big({\rm 5}+{\rm 2}\sqrt{4-3 f^2}\big)$. Here, the symbols $\chi, f = \vert\boldsymbol{F}\vert/$ ($cE$), and $c$, denote the Eddington factor, the reduced flux, and the speed of light, respectively. We evaluate the numerical flux across the cell surface from the kinetically reconstructed intensity. It is an explicit function of $E$ and $\boldsymbol{F}$ in the neighboring cells across the surface considered. We include absorption and reemission within a numerical cell in evaluating the numerical flux. The numerical flux approaches the diffusion approximation when the numerical cell, itself, is optically thick. Our numerical flux gives a stable solution even when some regions computed are very optically thick. We show the advantages of the numerical flux with examples. They include a flash of beamed photons and irradiated protoplanetary disks.