bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Black Hole Mass Estimation from X-Ray Spectra of Ultraluminous X-Ray Sources
Authors: Vierdayanti Kiki , Watarai Ken-ya , Mineshige Shin 
Published: March 2014

Abstract
We propose a methodology to derive a black-hole mass for super-critical accretion flow. Here, we use the extended disk blackbody (extended DBB) model, a fitting model in which the effective temperature profile obeys the relation $T_{\rm eff} \propto r^{-p}$, with $r$ being the disk radius and $p$ being treated as a fitting parameter. We first numerically calculate the theoretical flow structure and its spectra for a given black-hole mass, $M$, and accretion rate, $\dot{M}$. Through fitting to the theoretical spectra by the extended DBB model, we can estimate the black-hole mass, $M_{\rm x}$, assuming that the innermost disk radius is $r_{\rm in}=3r_{\rm g} (\propto M_{\rm x})$, where $r_{\rm g}$ is the Schwarzschild radius. We find, however, that the estimated mass deviates from that adopted in the spectral calculations, $M$, even for low-$\dot{M}$ cases. We also find that the deviations can be eliminated by introducing a new correction for the innermost radius. Using this correction, we calculate mass correction factors, $M/M_{\rm x}$, in the super-critical regimes for some sets of $M$ and $\dot M$, finding that a mass correction factor ranges between $M/M_{\rm x} \sim$1.2-1.6. The higher is $\dot{M}$, the larger does the mass correction factor tend to be. Since the correction is relatively small, we can safely conclude that the black holes in ULXs, which Vierdayanti et al. (2006, PASJ, 58, 915) analyzed, are stellar-mass black holes with the mass being $&lt;100M_{\odot}$.
Enrichment of Lead (Pb) in the Galactic Halo
Authors: Aoki Wako , Honda Satoshi 
Published: March 2014

Abstract
We determined lead (Pb) abundances for 12 red giants with the stellar metallicity [Fe$/$H] ranging between $-2.1$ and $-1.3$ and its upper limits for 2 lower-metallicity objects, as well as lanthanum (La) and europium (Eu) abundances. The averages of [Pb$/$Fe] and [Pb$/$Eu] were $-0.3$ and $-0.6$, respectively, and no clear increase of these ratios with increasing metallicity was found. The [La$/$Eu] values are only slightly higher than that of the $r$-process component in solar-system material. These results, together with the previous studies for globular clusters, suggest a small contribution of the $s$-process to the Pb abundance of the field stars studied here, supporting an estimate of Pb production by the $r$-process from the solar-system abundances.
Clustering of Emission-Line Stars in the W 5 E H ii Region
Authors: Nakano Makoto , Sugitani Koji , Niwa Takahiro , Itoh Yoichi , Watanabe Makoto 
Published: March 2014

Abstract
We have made a new survey of emission-line stars in the W 5 E H ii region to investigate the population of PMS stars near the OB stars by using the Wide Field Grism Spectrograph 2 (WFGS2). A total of 139 H$\alpha$ emission stars were detected and their $g'i'$-photometry was performed. Their spatial distribution shows three aggregates, i.e., two aggregates near the bright-rimmed clouds at the edge of the W 5 E H ii region (BRC 13 and BRC 14) and one near the exciting O7V star. The age and mass of each H$\alpha$ star were estimated from an extinction–corrected color-magnitude diagram and theoretical evolutionary tracks. We found, for the first time in this region, that the young stars near the exciting star are systematically older (4 Myr) than those near the edge of the H ii region (1 Myr). This result supports that the formation of stars proceeds sequentially from the center of H ii region to the eastern bright rim. We further suggest a possibility that the birth of low-mass stars near the exciting star of the H ii region precedes the production of massive OB stars in the pre-existing molecular cloud.
The FFX Correlator
Authors: Iguchi Satoru , Okuda Takeshi 
Published: March 2014

Abstract
We established a new algorithm for a correlation process in radio astronomy. This scheme consists of a 1st-stage Fourier transform as a filter and a 2nd-stage Fourier transform for spectroscopy. The “FFX” correlator stands for Filter and FX architecture, since the 1st-stage Fourier transform is performed as a digital filter, and the 2nd-stage Fourier transform is performed as a conventional FX scheme. We developed FFX correlator hardware not only for verifying the FFX scheme algorithm, but also for applying to the Atacama Submillimeter Telescope Experiment (ASTE) telescope toward high-dispersion and wideband radio observations at submillimeter wavelengths. In this paper, we present the principle of the FFX correlator and its properties, as well as evaluation results with the production version.
Multiple-Component Analysis of the Time-Resolved Spectra of GRB041006: A Clue to the Nature of the Underlying Soft Component of GRBs
Authors: Shirasaki Yuji , Yoshida Atsumasa , Kawai Nobuyuki , Tamagawa Toru , Sakamoto Takanori , Suzuki Motoko , Nakagawa Yujin , Kobayashi Akina , Sugita Satoshi , Takahashi Ichiro , Arimoto Makoto , Shimokawabe Takashi , Pazmino Nicolas Vasquez , Ishimura Takuto , Sato Rie , Matsuoka Masaru , Fenimore Edward E. , Galassi Mark , Lamb Donald Q. , Graziani Carlo , Donaghy Timothy Q. , Atteia Jean-Luc , Pelangeon Alexandre , Vanderspek Roland , Crew Geoffrey B. , Doty John P. , Villasenor Joel , Prigozhin Gregory , Butler Nat , Ricker George R. , Hurley Kevin , Woosley Stanford E. , Pizzichini Graziella 
Published: March 2014

Abstract
GRB041006 was detected by HETE-2 on 2004 October 06. The light curves in four different energy bands display different features. At higher energy bands several peaks are seen in the light curve, while at lower energy bands a single broader bump dominates. It is expected that these different features are the result of a mixture of several components, each of which has different energetics and variability. We analyzed the time-resolved spectra, which were resolved into several components. These components can be classified into two distinct classes. One is a component that has an exponential decay of $E_{\rm p}$ with a characteristic timescale shorter than $\sim\;$30 s; its spectrum is well represented by a broken power-law function, which is frequently observed in many prompt GRB emissions, so it should have an internal-shock origin. Another is a component whose $E_{\rm p}$ is almost unchanged with a characteristic timescale longer than $\sim\;$60 s, and shows a very soft emission and slower variability. The spectrum is characterized by either a broken power law or a black-body spectrum. By assuming that the soft component is a thermal emission, the radiation radius is initially $4.4 \times 10^{6}$km, which is a typical radius of a blue supergiant, and its expansion velocity is $2.4 \times 10^{5}$km s$^{-1}$ in the source frame.
Variable Asymmetry of the Circumstellar Envelope in IK Tauri Traced by SiO Maser Emission
Authors: Matsumoto Naoko , Omodaka Toshihiro , Imai Hiroshi , Shimizu Rie , Bushimata Takeshi , Choi Yoon Kyung , Hirota Tomoya , Honma Mareki , Inomata Noritomo , Iwadate Kenzaburo , Jike Takaaki , Kameno Seiji , Kameya Osamu , Kamohara Ryuichi , Kan-Ya Yukitoshi , Kawaguchi Noriyuki , Kobayashi Hideyuki , Kuji Seisuke , Kurayama Tomoharu , Maeda Toshihisa , Manabe Seiji , Miyaji Takeshi , Nakagawa Akiharu , Nagayama Takumi , Nakashima Koichiro , Oh Chung Sik , Oyama Tomoaki , Sakai Satoshi , Sakakibara Seiichiro , Sasao Tetsuo , Sato Katsuhisa , Shibata Katsunori M. , Shintani Motonobu , Sofue Yoshiaki , Sora Kasumi , Suda Hiroshi , Tamura Yoshiaki , Tsushima Miyuki , Yamashita Kazuyoshi 
Published: March 2014

Abstract
We observed the SiO ($v=1$ and $v=2$, $J=$ 1-0) maser emissions toward the Mira variable IK Tauri (IK Tau, NML Tau, IRC$+$10050) over nine epochs from 2003 November to 2005 April using the VLBI Exploration of Radio Astrometry (VERA) telescope array. We found that the SiO maser distributions around IK Tau are highly variable, depending on the stellar pulsation phase. The velocity structures were complex and also time-variable, and are inconsistent with a simply rotating shell that was suggested by previous observations. Based on fittings of the SiO maser distributions to elliptical ring models, we found that the ring size seems to vary in correlation with the pulsation phase, as previously found for TX Cam. Comparisons of the $v=1$ and $v=2$ maser distributions reveal that 42-50% of the maser pairs have a positional offset less than 0.5mas, suggesting that the maser pumping in these spots is likely to be dominated by line overlapping or collisional pumping, rather than pure radiative pumping. In order to model the velocity structure of the spoke-like features observed in IK Tau, we propose a ballistic-orbit model, in which a gas clump ejected from the stellar surface moves radially outward with a gravitational deceleration, and argue that the stellar mass can be deduced from that model.
Large-Scale NH3 Observations toward the Galactic Star-Forming Regions I. W 51 Molecular Cloud Complex
Authors: Sorai Kazuo , Habe Asao , Nishitani Hiroyuki , Hosaka Keita , Watanabe Yoshimasa , Miwa Shinichi , Ohishi Yukie , Motogi Kazuhito , Minamidani Tetsuhiro , Awano Johta , Sumida Sakurako , Fukuya Yoshiaki , Uchida Ryosuke , Kaneko Noboru , Fujimoto Masayuki Y. , Koyama Yasuhiro , Kimura Moritaka , Nakai Naomasa 
Published: March 2014

Abstract
Large-area observations of dense molecular gas were made in NH$_{3}$ ($J$, $K$) $=$ (1, 1), (2, 2), and (3, 3) inversion lines with 4'.5 resolution toward the molecular cloud complex of the W51 region. The observations were a part of a NH$_{3}$ survey of the Galactic star-forming regions using the Tomakomai 11-m radio telescope. NH$_{3}$ ($J$, $K$) $=$ (1, 1) and (2, 2) emission was detected in the W51 A and B complexes, while the detection of ($J$, $K$) $=$ (2, 2) emission was marginal in W51 B. The rotation temperature was $\sim$40K in the central part of the W51 A complex, while being $\sim$20K in the other positions. A weak correlation is found that the ortho-to-para ratio decreases with increasing the rotation temperature, the far-infrared luminosity and the index of the star-formation efficiency. This tendency is explained if star formation has continued for more than the time scale of the transformation between ortho- and para-NH$_{3}$: active star formation on a large scale, such as the interaction of molecular clouds with a spiral arm, has made the molecular gas warmer, even in a scale of $\sim$10pc, and the proceeding transformation has made the ortho-to-para ratio lower.
Catalogue of 12CO(J = 1−0) and 13CO(J = 1−0) Molecular Clouds in the Carina Flare Supershell
Authors: Dawson Joanne R. , Kawamura Akiko , Mizuno Norikazu , Onishi Toshikazu , Fukui Yasuo 
Published: March 2014

Abstract
We present a catalogue of $^{12}$CO($J=$ 1-0) and $^{13}$CO($J=$ 1-0) molecular clouds in the spatio-velocity range of the Carina Flare supershell, GSH287$+$04$-$17. The data cover a region of $\sim$66 square degrees and were taken with the NANTEN 4m telescope, at spatial and velocity resolutions of $\sim$2.6' and 0.1kms$^{-1}$. Decomposition of the emission results in the identification of 156 $^{12}$CO clouds and 60 $^{13}$CO clouds, for which we provide observational and physical parameters. Previous work suggests the majority of the detected mass forms part of a comoving molecular cloud complex that is physically associated with the expanding shell. The cloud internal velocity dispersions, degree of virialization and size-linewidth relations are found to be consistent with those of other Galactic samples. However, the vertical distribution is heavily skewed towards high-altitudes. The robust association of high-$z$ molecular clouds with a known supershell provides some observational backing for the theory that expanding shells contribute to the support of a high-altitude molecular layer.
Planetary Companions to Evolved Intermediate-Mass Stars: 14 Andromedae, 81 Ceti, 6 Lyncis, and HD167042
Authors: Sato Bun'ei , Toyota Eri , Omiya Masashi , Izumiura Hideyuki , Kambe Eiji , Masuda Seiji , Takeda Yoichi , Itoh Yoichi , Ando Hiroyasu , Yoshida Michitoshi , Kokubo Eiichiro , Ida Shigeru 
Published: March 2014

Abstract
We report on the detection of four extrasolar planets orbiting evolved intermediate-mass stars from a precise Doppler survey of G-K giants at Okayama Astrophysical Observatory. All of the host stars are considered to be formerly early F-type or A-type dwarfs when they were on the main sequence. 14 And (K0 III) is a clump giant with a mass of 2.2$M_{\odot}$ and has a planet of minimum mass $m_2$sin$i$$=$ 4.8$M_{\rm J}$ in a nearly circular orbit with a 186d period. This is one of the innermost planets around evolved intermediate-mass stars, and such planets have only been discovered in clump giants. 81 Cet (G5 III) is a clump giant with 2.4$M_{\odot}$ hosting a planet of $m_2$sin$i$$=$ 5.3$M_{\rm J}$ in a 953d orbit with an eccentricity of $e=$ 0.21. 6 Lyn (K0 IV) is a less-evolved subgiant with 1.7$M_{\odot}$, and has a planet of $m_2$sin$i$$=$ 2.4$M_{\rm J}$ in a 899d orbit with $e=$ 0.13. HD167042 (K1 IV) is also a less-evolved star with 1.5$M_{\odot}$ hosting a planet of $m_2$sin$i$$=$ 1.6$M_{\rm J}$ in a 418d orbit with $e=$ 0.10. This planet was independently announced by Johnson et al. (2008, ApJ, 675, 784). All of the host stars have solar or sub-solar metallicity, which supports the lack of a metal-rich tendency in planet-harboring giants in contrast to the case of dwarfs.
Multi-Object Infrared Camera and Spectrograph (MOIRCS) for the Subaru Telescope* I. Imaging
Authors: Suzuki Ryuji , Tokoku Chihiro , Ichikawa Takashi , Uchimoto Yuka Katsuno , Konishi Masahiro , Yoshikawa Tomohiro , Tanaka Ichi , Yamada Toru , Omata Koji , Nishimura Tetsuo 
Published: March 2014

Abstract
MOIRCS is a fully cryogenic near-infrared instrument for the 8.2 m Subaru Telescope. MOIRCS has two observation modes: a wide-field imaging mode and a multiobject spectroscopy mode. This paper describes the imaging mode, its specifications, and actual performances that we confirmed through laboratory tests and commissioning observations. The imaging mode provides a 4' $\times$ 7' field of view with a pixel scale of 0”.117pixel$^{-1}$ in the wavelength range of 0.85 to 2.5$\mu$ using cooled optics and two 2048 $\times$ 2048 HgCdTe HAWAII-2 focal plane arrays. Good-quality images are obtained over the entire field of view with practically no chromatic aberration. The limiting magnitudes for a point source estimated from observed background brightness and throughput are 23.7 in the $J$ band, 23.0 in the $H$ band, and 22.6 in the $K_{\rm s}$ band (Vega) with $S/N$$=$ 5, 0”.5 seeing, 1”.0 aperture, and 1hr exposure.
Abundance Inhomogeneity in the Northeastern Rim of the Cygnus Loop Revealed by the Suzaku Observatory
Authors: Katsuda Satoru , Tsunemi Hiroshi , Uchida Hiroyuki , Miyata Emi , Nemes Norbert , Miller Eric D. , Mori Koji , Hughes John. P. 
Published: March 2014

Abstract
We present the results of a spatially resolved spectral analysis from four Suzaku observations covering the northeastern rim of the Cygnus Loop. A two-$kT_\mathrm{e}$ non-ionization equilibrium (NEI) model fairly well represents our data, which confirms the NEI condition of the plasma there. The metal abundances are depleted relative to the solar values almost everywhere in our field of view. We find abundance inhomogeneities across the field: the northernmost region (Region A) has enhanced absolute abundances compared with other regions. In addition, the relative abundances of Mg$/$O and Fe$/$O in Region A are lower than the solar values, while those in the other regions are twice higher than the solar values. As far as we are concerned, neither a circumstellar medium, fragments of ejecta, nor abundance inhomogeneities of the local interstellar medium around the Cygnus Loop can explain the relatively enhanced abundance in Region A. This point is left as an open question for future work.
A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole
Authors: Koyama Katsuji , Inui Tatsuya , Matsumoto Hironori , Tsuru Takeshi Go 
Published: March 2014

Abstract
A time-variability study of the neutral iron line flux at 6.40keV in the Sgr B2 region from data of Suzaku and Chandra is presented. The highly ionized iron line at 6.68keV is due to Galactic Center Diffuse X-rays, and is thus time invariable. By comparing the 6.68keV and 6.40keV line fluxes, we found that the 6.40keV flux from the Sgr B2 complex region is time variable; particularly the giant molecular cloud M 0.66$-$0.02, known as “Sgr B2 cloud” is highly variable. The variability of the 6.40keV line in intensity and spatial distribution strongly supports the scenario that the molecular clouds in the Sgr B2 region are X-ray Reflection Nebulae irradiated by the Galactic Center black hole Sgr A$^*$.
Discovery of a Bright Transient Ultraluminous X-Ray Source, Suzaku J1305–4931 in NGC4945
Authors: Isobe Naoki , Kubota Aya , Makishima Kazuo , Gandhi Poshak , Griffiths Richard E. , Dewangan Gulab C. , Itoh Takeshi , Mizuno Tsunefumi 
Published: March 2014

Abstract
An X-ray source, Suzaku J1305$-$4931, was discovered in the south-west arm of a nearby Seyfert II galaxy, NGC4945, at 0.5-10keV flux of $2.2 \times 10^{-12}$ergcm$^{-2}$s$^{-1}$ during a Suzaku observation conducted on 2006 January 15-17. It was undetectable in a shorter observation on 2005 August 22-23, with an upper limit of $1.7 \times 10^{-14}$ergcm$^{-2}$s$^{-1}$. At a distance of 3.7Mpc, the bolometric luminosity of the source became $L_{\rm bol} = 4.4 \times 10^{39} \alpha$ergs$^{-1}$, where $\alpha = ({\rm\cos} 60^\circ \!/ \cos i)$ and $i$ is the disk inclination. The time-averaged X-ray spectrum of the source is described by a multi-color disk model, with an innermost disk temperature of $T_{\rm in} = 1.69_{-0.05}^{+0.06}$keV. It varied by a factor of $2$ in intensity, following a clear correlation of $L_{\rm bol} \propto T_{\rm in}^4$. The innermost disk radius is inferred to stay constant at $R_{\rm in} = 79_{-3.9}^{+4.0} \alpha^{1/2}$ km, suggesting the presence of a standard accretion disk. Relating $R_{\rm in}$ with the last stable orbit around a non-rotating black hole yields a rather low black-hole mass, $\sim 9 \alpha^{1/2}$ solar masses, which would imply that the source is shining at a considerable super-Eddington luminosity. These results can be better interpreted by invoking sub-Eddington emission from a rapidly spinning black hole with 20-130 solar masses.
In-Orbit Timing Calibration of the Hard X-Ray Detector on Board Suzaku
Authors: Terada Yukikatsu , Enoto Teruaki , Miyawaki Ryouhei , Ishisaki Yoshitaka , Dotani Tadayasu , Ebisawa Ken , Ozaki Masanobu , Ueda Yoshihiro , Kuiper Lucien , Endo Manabu , Fukazawa Yasushi , Kamae Tsuneyoshi , Kawaharada Madoka , Kokubun Motohide , Kuroda Yoshikatsu , Makishima Kazuo , Masukawa Kazunori , Mizuno Tsunefumi , Murakami Toshio , Nakazawa Kazuhiro , Nakajima Atsushi , Nomach Masaharu , Shibayama Naoki , Takahashi Tadayuki , Takahashi Hiromitsu , Tashiro Makoto S. , Tamagawa Toru , Watanabe Shin , Yamaguchi Makio , Yamaoka Kazutaka , Yonetoku Daisuke 
Published: March 2014

Abstract
The hard X-ray detector (HXD) aboard the X-ray satellite Suzaku is designed to have a good timing capability with a 61$\mu$s time resolution. In addition to detailed descriptions of the HXD timing system, results of in-orbit timing calibration and the performance of the HXD are summarized. The relative accuracy of time measurements of the HXD event was confirmed to have an accuracy of $1.9\times 10^{-9}$s s$^{-1}$ per day, and the absolute timing was confirmed to be accurate to 360$\mu$s or better. The results were achieved mainly through observations of the Crab pulsar, including simultaneous ones with RXTE, INTEGRAL, and Swift.
Suzaku Observation of the Metallicity in the Hot Interstellar Medium of the Isolated Elliptical Galaxy NGC 720
Authors: Tawara Yuzuru , Matsumoto Chiho , Tozuka Miyako , Fukazawa Yasushi , Matsushita Kyoko , Anabuki Naohisa 
Published: March 2014

Abstract
The metal abundances in the interstellar medium of the isolated elliptical galaxy NGC 720 were studied with the CCD X-ray Imaging Spectrometer (XIS) aboard the Suzaku satellite. The high detection efficiency along with the excellent spectral resolution of the XIS allowed the K-shell lines of O and Mg to be clearly resolved, and the abundances of O, Ne, Mg, Si, and Fe to be measured with good accuracy for the region within a 3$'$ radius of NGC 720. The abundances of O and Mg were well determined to be 0.4 and 0.5 solar respectively, meaning stellar metallicity of mass-losing stars in NGC 720 was also well determined. The abundance of Fe was determined to be about 0.7 solar, while the O$/$Fe, Ne$/$Fe abundance ratios were found to be about 0.5 and Mg$/$Fe, Si$/$Fe were found to be 0.7 in solar units. Relative errors of 30% for the O$/$Fe, Ne$/$Fe, Mg$/$Fe abundance ratios are the lowest among isolated elliptical galaxies so far observed. The higher abundance of Fe than those of O, Ne, and Mg supplied by stellar mass loss indicates that iron is enhanced by SN Ia in NGC 720. These abundance ratios are consistent with those in the ISM of NGC 1399, NGC 1404, and in the ICM of the Fornax cluster observed with Suzaku.
Suzaku Observations of AWM 7 Cluster of Galaxies: Temperatures, Abundances, and Bulk Motions
Authors: Sato Kosuke , Matsushita Kyoko , Ishisaki Yoshitaka , Yamasaki Noriko Y. , Ishida Manabu , Sasaki Shin , Ohashi Takaya 
Published: March 2014

Abstract
We carried out 3 observations of the cluster of galaxies AWM 7, for the central region and $20'$-east and $20'$-west offset regions, with Suzaku. Temperature and abundance profiles were measured out to 27$'\simeq$570$\;h_{70}^{-1}$kpc, which corresponded to $\sim$0.35$r_{180}$. The temperature of the intra-cluster medium (ICM) slightly decreased from 3.8keV at the center to 3.4keV in the $\sim$0.35$r_{180}$ region, indicating a flatter profile than those in other nearby clusters. The abundance ratio of Si to Fe was almost constant in our observations, while the Mg-to-Fe ratio increased with radius from the cluster center. The O to Fe ratio in the west region showed an increase with radius, while that in the east region was almost flat, though the errors were relatively large. These features suggest that the enrichment process is significantly different between products of type II supernovae (O and Mg) and those by type Ia supernovae (Si and Fe). We also examined the positional shift of the central energy of a He-like Fe-K$\alpha$ line, in search of possible rotation of the ICM. The 90% upper limit for the line-of-sight velocity difference was derived to be $\Delta v \lesssim 2000$kms$^{-1}$, suggesting that the ellipticity of AWM 7 is rather caused by a recent directional infall of gas along the large-scale filament.