bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suzaku Observation of the Metallicity in the Interstellar Medium of NGC 4258
Authors: Konami Saori , Sato Kosuke , Matsushita Kyoko , Yamada Shin’ya , Isobe Naoki , Senda Atsushi , Hayato Asami , Gandhi Poshak , Tamagawa Toru , Makishima Kazuo 
Published: March 2014

Abstract
The Suzaku X-ray satellite observed the nearby spiral galaxy NGC 4258 for a total good exposure time of 100 ks. We present an analysis of the Suzaku XIS data, in which we confirm that the 0.5–2 keV spectra of the interstellar medium (ISM) are well-represented by a two-temperature model. The cool and hot ISM temperatures are 0.23 $\pm$ 0.01 and 0.58 $\pm$ 0.01 keV, respectively. Suzaku’s excellent spectral sensitivity has enabled us to measure the metal abundances of O, Ne, Mg, Si, and Fe of the ISM for the first time. The resultant abundance pattern of O, Mg, Si, and Fe is consistent with that of the new solar abundance table of Lodders (2003, ApJ, 591, 1220), rather than Anders and Grevesse (1989, Geochim. Cosmochim. Acta, 53, 197). This suggests that the metal enrichment processes of NGC 4258 and of our Galaxy are similar.
Force-Free Black Hole Magnetospheres
Authors: Okamoto Isao 
Published: March 2014

Abstract
It is argued that a force-free degenerate electrodynamic (FFDE) magnetosphere of a Kerr black hole with 0 $\lt$$\Omega _{\rm F}$$\lt$${\Omega_{\rm H}}$ consists of the outer classical and inner general-relativistic domains. This is described by a simple DC dual-circuit model, with dissipative membranes as two loads at a “force-free infinity surface” (S$_{{\rm ff}\infty }$) with $\omega$$=$ 0 and at a “force-free horizon surface” (S$_{\rm ffH}$) with $\omega$$=$${\Omega_{\rm H}}$, where $\omega$, ${\Omega_{\rm H}}$, and $\Omega _{\rm F}$ are the frame-dragging, the horizon and the field line angular frequencies. It is beneath upper null surface, S$_{\rm N}$, at $\omega$$=$$\Omega _{\rm F}$ between the two domains that dual unipolar batteries (double EMF’s) exist back-to-back, oppositely directed, with a pair-creation gap between. The total energy flux ${\boldsymbol{S}}_E$ is a linear sum of the two fluxes: the hole’s outward spin-down energy flux ${\boldsymbol{S}}_{\rm SD}$ originating at S$_{\rm ffH}$ and the Poynting flux $\boldsymbol{S}_{\rm EM}$ emitted at S$_{\rm N}$ in both the outward and inward directions, with ${\boldsymbol{S}}_E$ being proportional to $\Omega _{\rm F}$, ${\boldsymbol{S}}_{\rm SD}$ to $\omega$ and $\boldsymbol{S}_{\rm EM}$ to ($\Omega _{\rm F}$$-$$\omega$) along each field line. Applying a perturbation method for a split-monopolar field with a spin-parameter $h$$\ll$ 1, the analytic solution of the stream equation is given, and the double eigenvalue problem due to the `criticality condition’ at the outer/inner fast surfaces S$_{\rm oF}$/S$_{\rm iF}$ and the `boundary condition’ at S$_{\rm N}$ is solved to yield the final eigenvalue $\Omega _{\rm F}$, in terms of ${\Omega_{\rm H}}$ and $f_{\rm H}$$=$ 0.5676. The ratio of the output power reaching S$_{{\rm ff}\infty }$ to the dissipation on S$_{\rm ffH}$ is $\epsilon$$=$ 1 $+$ (4$/$5)(1 $-$$f_{\rm H}$) $h^2$.
A Photometric Study of the Near-Contact Binary WY Tauri
Authors: Yang Yuan-Gui 
Published: March 2014

Abstract
CCD photometric observations for the eclipsing binary WY Tauri are firstly presented. Three new minimum timings in 2006 and 2008 have been determined. Using Wilson–Devinney binary code, the photometric solution was simultaneously deduced from $VR$ light curves. Photometric results indicate that WY Tau is a semi-detached binary, whose secondary component fills its Roche lobe. The mass ratio and orbital inclination are $q$$=$ 0.508($\pm$0.006) and $i$$=$ 78${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$0($\pm$0${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$05), respectively. The filling factor of the primary component is 84.9%, indicating that this star is a near-contact binary. Based on all available eclipse timings since 1930, it is found that the ($O-C$) curve may be described by either a long-term period increase or a cyclic variation. The continuous period increase at a rate of $dP/dt$$=$$+$4.65 $\times$ 10$^{-8} $d yr$^{-1}$ may be attributed to mass transferring from the secondary to the primary, identified by the semidetached configuration. With mass transferring, WY Tau may evolve into a contact binary.
GreeM: Massively Parallel TreePM Code for Large Cosmological N-body Simulations
Authors: Ishiyama Tomoaki , Fukushige Toshiyuki , Makino Junichiro 
Published: March 2014

Abstract
In this paper, we describe the implementation and performance of GreeM, a massively parallel TreePM code for large-scale cosmological N-body simulations. GreeM uses a recursive multi-section algorithm for domain decomposition. The size of the domains are adjusted so that the total calculation time of the force becomes the same for all processes. The loss of performance due to non-optimal load balancing is around 4%, even for more than 10$^3$ CPU cores. GreeM runs efficiently on PC clusters and massively-parallel computers, such as a Cray XT4. The measured calculation speed on Cray XT4 is 5 $\times$ 10$^4$ particles per second per CPU core, for the case of an opening angle of $\theta$$=$ 0.5, if the number of particles per CPU core is larger than 10$^6$.
Broad-Band Temporal and Spectral Variation of 36 Active Galactic Nuclei Observed with Suzaku
Authors: Miyazawa Takuya , Haba Yoshito , Kunieda Hideyo 
Published: March 2014

Abstract
36 AGN data observed by Suzaku were compiled to examine the temporal variability in different energy bands covered by soft X-ray imaging systems (XRT $+$ XIS: 0.5–10 keV) and Hard X-ray Detector (HXD: 15–50 keV) aboard Suzaku. Three band light curves were obtained in L (0.5–2 keV), M (2–10 keV), and H (15–50 keV) with a time binning of 5760 s. The L-band flux change was almost proportional to that of the M-band without offsets in most of type-1 AGNs. The slope ($=$$dL/dM$) of the correlation changed by more than a factor of 10 from Seyfert 2 to narrow-line Seyfert 1 galaxies (NLS1). The power-law component can explain the slope of Seyfert 1 galaxies with a typical index, $\Gamma$, of 1.9. For NLS1 s with steeper slopes, an additional soft excess component is needed, whose variation should be proportional to that of the power-law component. It gives a new constraint to models for the soft excess component. The H-band flux change is a linear function of the M-band flux with a significant offset in the H-band. The slope can be explained by the power-law component with an absorption column from 10$^{22{-}24} $cm$^{-2}$. The offset can be attributed to the reflection component, which is stable on a time scale of days.
Another Abundance Inhomogeneity in the South East Limb of the Cygnus Loop
Authors: Tsunemi Hiroshi , Kimura Masashi , Uchida Hiroyuki , Mori Koji , Katsuda Satoru 
Published: March 2014

Abstract
We observed the south east (SE) limb of the Cygnus Loop with Suzaku. Our spatially-resolved spectroscopic study shows that a one-$kT_\mathrm{e}$ non-equilibrium ionization model represents our spectra fairly well. We find that the metal abundances obtained are all depleted relative to the solar values with a positional dependence along the radial direction of the Cygnus Loop. The abundances in the very edge of the limb show about half the solar value, whereas other regions inside the Loop show about 0.2-times the solar value, which has been believed to be a typical value for the Cygnus Loop limb. The “enhanced” abundance in the very edge of the SE limb is quite similar to that found in the north-east (NE) limb of the Loop, and thus this is another evidence of an abundance inhomogeneity in the limb regions of the Loop. The radio map shows a quite different feature: the NE limb is in the radio bright region, while the SE limb shows almost no radio. Therefore, the metal abundance variation in the SE limb can not be attributed to non-thermal emission. The abundance inhomogeneity as well as the metal depletion down to 0.2 times the solar value still remain an open question.
The Nature of a Cosmic-Ray Accelerator, CTB 37 B, Observed with Suzaku and Chandra
Authors: Nakamura Ryoko , Bamba Aya , Ishida Manabu , Nakajima Hiroshi , Yamazaki Ryo , Terada Yukikatsu , Pühlhofer Gerd , Wagner Stefan J. 
Published: March 2014

Abstract
We report on Suzaku and Chandra observations of the young supernova remnant CTB 37 B, from which TeV $\gamma$-rays were detected by the H.E.S.S. Cherenkov telescope. The 80 ks Suzaku observation provided us with a clear image of diffuse emission and high-quality spectra. The spectra revealed that the diffuse emission is comprised of thermal and non-thermal components. The thermal component can be represented by an NEI model with a temperature, a pre-shock electron density and an age of 0.9$\pm$0.2 keV, 0.4$\pm$0.1 cm$^{-3}$, and 650$^{+2500}_{-300}$yr, respectively. This suggests that the explosion of CTB 37 B occurred in a low-density space. A non-thermal power-law component was found from the southern region of CTB 37 B. Its photon index of $\sim$1.5 and a high roll-off energy ($&gt;rsim$15 keV) indicate efficient cosmic-ray acceleration. A comparison of this X-ray spectrum with the TeV $\gamma$-ray spectrum leads us to conclude that the TeV $\gamma$-ray emission seems to be powered by either multi-zone Inverse Compton scattering or the decay of neutral pions. The point source resolved by Chandra near the shell is probably associated with CTB 37 B, because of the common hydrogen column density with the diffuse thermal emission. Spectral and temporal characteristics suggest that this source is a new anomalous X-ray pulsar.
Suzaku Observations of M 82 X-1 : Detection of a Curved Hard X-Ray Spectrum
Authors: Miyawaki Ryohei , Makishima Kazuo , Yamada Shin’ya , Gandhi Poshak , Mizuno Tsunefumi , Kubota Aya , Tsuru Takeshi G. , Matsumoto Hironori 
Published: March 2014

Abstract
A report is presented on Suzaku observations of the ultra-luminous X-ray source X-1 in the starburst galaxy M 82, made three times in 2005 October for an exposure of $\sim$30 ks each. The XIS signals from a region of radius 3$^\prime$ around the nucleus defined a 2–10 keV flux of 2.1$\times$10$^{-11}$ergs$^{-1}$cm$^{-2}$ attributable to point sources. The 3.2–10 keV spectrum was slightly more convex than a power-law with a photon index of 1.7. In all observations, the HXD also detected signals from M 82 up to $\sim$20 keV, at a 12-20 keV flux of 4.4$\times$10$^{-12}$ergs$^{-1}$cm$^{-2}$. The HXD spectrum was steeper than that of the XIS. The XIS and HXD spectra can be jointly reproduced by a cutoff power-law model, or similar curved models. Of the detected wide-band signals, 1$/$3 to 2$/$3 are attributable to X-1, while the remainder to other discrete sources in M 82. Regardless of the modeling of these contaminants, the spectrum attributable to X-1 is more curved than a power-law, with a bolometric luminosity of (1.5–3)$\times$10$^{40}$ergs$^{-1}$. These results are interpreted as Comptonized emission from a black hole of 100–200 solar masses, radiating roughly at the Eddington luminosity.
Spectral Transitions of an Ultraluminous X-Ray Source, NGC 2403 Source 3
Authors: Isobe Naoki , Makishima Kazuo , Takahashi Hiromitsu , Mizuno Tsunefumi , Miyawaki Ryouhei , Gandhi Poshak , Kawaharada Madoka , Senda Atsushi , Yoshida Tessei , Kubota Aya , Kobori Hiroshi 
Published: March 2014

Abstract
A Suzaku observation of an ultraluminous X-ray source, NGC 2403 Source 3, performed on 2006 March 16–17, is reported. The Suzaku XIS spectrum of Source 3 was described as multi-color black-body-like emission from an optically thick accretion disk. The innermost disk temperature and radius were measured to be $T_{\rm in}$$=$ 1.08$_{-0.03}^{+0.02}$keV and $R_{\rm in}$$=$ 122.1$_{-6.8}^{+7.7} \ \alpha^{1/2}$km, respectively, where $\alpha$$=$ (cos 60$^\circ /$cos $i$) with $i$ being the disk inclination. Its bolometric luminosity was estimated to be $L_{\rm bol}$$=$ 1.82 $\times$ 10$^{39}\alpha $ergs$^{-1}$. Archival Chandra and XMM-Newton data of the source were analyzed. In almost all observations, the source showed multi-color black-body-like X-ray spectra with parameters similar to those of the Suzaku observation. In only one Chandra observation, however, Source 3 exhibited a power-law-like spectrum, with a photon index of $\Gamma$$=$ 2.37$\pm$0.08, when it was fainter by $\sim$15% than in the Suzaku observation. This behavior is explained in terms of a transition between a slim-disk state and “very high” states, both found in Galactic black hole binaries, when their luminosity apporached the Eddington limit. These results are utilized to argue that ultraluminous X-ray sources generally have significantly higher masses than ordinary stellar-mass black holes.
X-Ray Halo around the Spiral Galaxy NGC 4631 Observed with Suzaku
Authors: Yamasaki Noriko Y. , Sato Kosuke , Mitsuishi Ikuyuki , Ohashi Takaya 
Published: March 2014

Abstract
A Suzaku observation of the edge-on spiral galaxy NGC 4631 confirmed its X-ray halo extending out to about 10 kpc from the galactic disk. The XIS spectra yielded the temperature and metal abundance for the disk and the halo regions. The observed abundance pattern for O, Ne, Mg, Si, and Fe is consistent with the metal yield from type II supernovae, with an O mass of about 10$^{6}M_\odot$ contained in the halo. These features imply that metal-rich gas produced by type II supernova is brought into the halo region very effectively, most likely through a galactic wind. The temperature and metal abundance may be affected by charge exchange and dust. An upper limit for the hard X-ray flux was obtained, corresponding to a magnetic field higher than 0.5$\mu$G.
Suzaku Observations of Metallicity Distribution in the Intracluster Medium of the NGC 5044 Group
Authors: Komiyama Madoka , Sato Kosuke , Nagino Ryo , Ohashi Takaya , Matsushita Kyoko 
Published: March 2014

Abstract
The metallicity distribution in the intracluster medium of the NGC 5044 group was studied up to 0.3 $r_{180}$ using the XIS instrument aboard the Suzaku satellite. The abundances of O, Mg, Si, S, and Fe were measured with high accuracy. The region within a radius of 0.05 $r_{180}$ from the center shows approximately solar abundances of Mg, Si, S, and Fe, while the O$/$Fe ratio is about 0.5–0.6 in solar units. In the outer region, the Fe abundance gradually drops to 0.3 solar. The radial abundance profiles of Mg, Si and S are similar to that of Fe, while that of O seems to be flatter. At $r$$&gt;$ 0.05 $r_{180}$, the mass density profile of O differs from that of Fe, showing a shoulder-like structure that traces the luminosity density profile of galaxies. The mass-to-light ratios for O and Fe in NGC 5044 are one of the largest among groups of galaxies, but they are still smaller than those in rich clusters. These abundance features probably reflect the metal enrichment history of this relaxed group hosting a giant elliptical galaxy in the center.
Suzaku Observation of Group of Galaxies NGC 507: Temperature and Metal Distributions in the Intra-Cluster Medium
Authors: Sato Kosuke , Matsushita Kyoko , Ishisaki Yoshitaka , Yamasaki Noriko Y. , Ishida Manabu , Ohashi Takaya 
Published: March 2014

Abstract
The temperature and abundance distributions of the intra-cluster medium (ICM) in the NGC 507 group of galaxies were studied with Suzaku. The observed concentric annular spectra were well-represented by a two-temperature model for ICM, and steeper abundance gradients were found for Mg, Si, S, and Fe compared with O in the central region. The abundance ratios of $\alpha$-elements to iron were found to be similar to those in other groups and poor clusters. We calculated the metal mass-to-light ratios for Fe, O, and Mg (IMLR, OMLR, MMLR) for NGC 507, and values for different systems were compared. Hotter and richer systems tend to show higher values of IMLR, OMLR, and MMLR. OMLR and MMLR were measured to an outer region for the first time with Suzaku, while IMLR was consistent with that with ASCA. We also looked into a 2-dimensional map of the hardness ratio, but found no significant deviation from circular symmetry.
Temperature and Metallicity in the Intra-Cluster Medium of Abell 262 Observed with Suzaku
Authors: Sato Kosuke , Matsushita Kyoko , Gastaldello Fabio 
Published: March 2014

Abstract
We studied the temperature and abundance distributions of the intra-cluster medium (ICM) in the Abell 262 cluster of galaxies observed with Suzaku. Abell 262 is a bright, nearby poor cluster with an ICM temperature of $\sim$2 keV, thus providing useful information about the connection of ICM properties between groups and clusters of galaxies. With the XIS instrument, we directly measured not only the Si, S, and Fe lines, but also the O and Mg lines, and obtained those abundances to an outer region of $\sim$ 0.43$r_{180}$ for the first time. We found steep gradients for Mg, Si, S, and Fe abundances, while O showed an almost flat abundance distribution. The abundance ratios of $\alpha$-elements to Fe were found to be similar to those of the other clusters and groups. We calculated the number ratio of type II to type Ia supernovae for the ICM enrichment to be 3.0$\pm$0.6 within 0.1$r_{180}$; the value was consistent with those for other clusters and groups. We also calculated the metal mass-to-light ratios (MLRs) for Fe, O, and Mg with $B$-band and $K$-band luminosities of the member galaxies of Abell 262. The derived MLRs were comparable to those for other clusters with $kT$$=$ 3–4 keV.
X-Ray Studies of HESS J1809–193 with Suzaku
Authors: Anada Takayasu , Bamba Aya , Ebisawa Ken , Dotani Tadayasu 
Published: March 2014

Abstract
Suzaku observed the region including HESS J1809$-$193, a TeV unidentified source, and confirmed the existence of extended hard X-ray emission previously reported by ASCA, as well as hard X-ray emission from PSR J1809$-$1917 in this region. A one-dimensional profile of the diffuse emission is represented along with a Gaussian model with a best-fit $\sigma$ of 7$^\prime \pm$ 1$^\prime$. The diffuse emission extends for at least 21 pc (at the 3$\sigma$ level, assuming a distance of 3.5 kpc), and has a hard spectrum with a photon index of $\Gamma \sim$ 1.7. The hard spectrum suggests a pulsar wind nebula origin, which is also strengthened by the hard X-ray emission from PSR J1809$-$1917, itself. Thanks to the low background of Suzaku XIS, we were able to investigate the spatial variation of the energy spectrum, but no systematic spectral change in the extended emission was found. These results imply that the X-ray emitting pulsar wind electrons can travel up to 21 pc from the pulsar without any noticeable energy loss via synchrotron emission.
Warm and Dense Molecular Gas in the N 159 Region: 12CO J = 4–3 and 13CO J = 3–2 Observations with NANTEN2 and ASTE
Authors: Mizuno Yoji , Kawamura Akiko , Onishi Toshikazu , Minamidani Tetsuhiro , Muller Erik , Yamamoto Hiroaki , Hayakawa Takahiro , Mizuno Norikazu , Mizuno Akira , Stutzki Jürgen , Pineda Jorge L. , Klein Uli , Bertoldi Frank , Koo Bon-Chul , Rubio Monica , Burton Michael , Benz Arnold , Ezawa Hajime , Yamaguchi Nobuyuki , Kohno Kotaro , Hasegawa Tetsuo , Tatematsu Ken’ichi , Ikeda Masafumi , Ott Jürgen , Wong Tony , Hughes Annie , Meixner Margaret , Indebetouw Remy , Gordon Karl D. , Whitney Barbara , Bernard Jean-Philippe , Fukui Yasuo 
Published: March 2014

Abstract
New $^{12}$CO $J =$ 4–3 and $^{13}$CO $J =$ 3–2 observations of the N 159 region, an active site of massive star formation in the Large Magellanic Cloud, have been made with the NANTEN2 and ASTE submillimeter telescopes, respectively. The $^{12}$CO $J =$ 4–3 distribution is separated into three clumps, each associated with N 159 W, N 159 E, and N 159 S. These new measurements toward the three clumps are used in coupled calculations of molecular rotational excitation and line radiation transfer, along with other transitions of the $^{12}$CO $J =$ 1–0, $J =$ 2–1, $J =$ 3–2, and $J =$ 7–6 as well as the isotope transitions of $^{13}$CO $J =$ 1–0, $J =$ 2–1, $J =$ 3–2, and $J =$ 4–3. The $^{13}$CO $J =$ 3–2 data were newly taken for the present work. The temperatures and densities were found to be $\sim$70&x2013;80 K and $\sim$3 $\times$ 10$^{3}$cm$^{-3}$ in N 159 W and N 159 E, and $\sim$30 K and $\sim$1.6 $\times$ 10$^{3}$cm$^{-3}$ in N 159 S. These results were compared with the star-formation activity based on data of young stellar clusters and HII regions as well as midinfrared emission obtained with the Spitzer MIPS. The N 159 E clump is associated with cluster(s) embedded, as observed at 24$\mu$m by the Spitzer MIPS, and the derived high temperature, 80 K, is interpreted as being heated by these sources. The N 159 E clump is likely to be responsible for a dark lane in a large H II region by dust extinction. On the other hand, the N 159 W clump is associated with clusters embedded mainly toward the eastern edge of the clump only. These clusters show offsets of 20${}^{\prime\prime}$–40${}^{\prime\prime}$ from the $^{12}$CO $J =$ 4–3 peak, and are probably responsible for heating indicated by the derived high temperature, 70 K. The N 159 W clump exhibits no sign of star formation toward the $^{12}$CO $J =$ 4–3 peak position and its western region that shows enhanced $R_{4-3/1-0}$ and $R_{3-2/1-0}$ ratios. We therefore suggest that the N 159 W peak represents a pre-star-cluster core of $\sim$10$^{5} M_{\odot}$ which deserves further detailed studies. The N 159 S clump shows little sign of star formation, as is consistent with the lower temperature, 30 K, and has a somewhat lower density than N 159 W and N 159 E. The N 159 S clump is also a candidate for future star formation.
SiO and H2O Maser Observations of Red Supergiants in Star Clusters Embedded in the Galactic Disk
Authors: Deguchi Shuji , Nakashima Jun-ichi , Zhang Yong , Chong Selina S. N. , Koike Kazutaka , Kwok Sun 
Published: March 2014

Abstract
We present the results of radio observations of red supergiants in a star cluster, Stephenson (1990, AJ, 99, 1867)’s #2, and of candidates for red supergiants in three star clusters, Mercer et al. (2005, ApJ, 635, 560)’s #4, #8, and #13, in the SiO and H$_2$O maser lines. The Stephenson’s #2 cluster and nearby aggregation at the southwest contain more than 15 red supergiants. We detected one red supergiant at the center of Stephenson’s #2 and three in a southwest aggregation in the SiO maser line; three out of these four were also detected in the H$_2$O maser line. The average radial velocity of the four detected objects is 97 km s$^{-1}$, giving a kinematic distance of 5.5 kpc, which locates this cluster near the base of the Scutum–Crux spiral arm. We also detected six SiO emitting objects associated with other star clusters. In addition, mapping observations in the CO $J =$ 1–0 line toward these clusters revealed that an appreciable amount of molecular gas still remains around the Stephenson’s #2 cluster in contrast to the prototypical red-supergiant cluster, Bica et al. (2003, A&A, 404, 223)’s #122. This indicates that the time scale of gas expulsion differs considerably in individual clusters.