bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristic Scales of Baryon Acoustic Oscillations from Perturbation Theory: Nonlinearity and Redshift-Space Distortion Effects
Authors: Takahiro Nishimichi , Ohmuro Hiroshi , Nakamichi Masashi , Taruya Atsushi , Yahata Kazuhiro , Shirata Akihito , Saito Shun , Nomura Hidenori , Yamamoto Kazuhiro , Suto Yasushi 
Published: March 2014

Abstract
An acoustic oscillation of the primeval photon-baryon fluid around the decoupling time imprints a characteristic scale in the galaxy distribution today, known as the baryon acoustic oscillation (BAO) scale. Several ongoing and/or future galaxy surveys aim to detect and precisely determine the BAO scale so as to trace the expansion history of the universe. We consider nonlinear and redshift-space distortion effects on the shifts of the BAO scale in $k$-space using perturbation theory. The resulting shifts are indeed sensitive to different choices for the definition of the BAO scale, which needs to be kept in mind in the data analysis. We present a toy model to explain the physical behavior of the shifts. We find that the BAO scale defined as in Percival et al. (2007, ApJ, 657, 51) indeed shows very small shifts ($\lesssim$1%) relative to the prediction in linear theory in real space. The shifts can be predicted accurately for scales where perturbation theory is reliable.
Is the Evolutionary Outcome of Algol-Type Systems T Leonis Minoris and RW Monocerotis the W UMa Systems?
Authors: Li Li-Fang , Jiang Tian-Yu , Zhang Feng-Hui , Han Zhan-Wen , Jiang Deng-Kai 
Published: March 2014

Abstract
The variations of the orbital periods of two Algol-type eclipsing binaries, T LMi and RW Mon, are presented through a detailed analysis of $(O-C)$ diagrams. It is found that, apart from a secular decrease, several sudden jumps have occurred in the orbital periods of both binary systems. The period decrease rate was derived to be $-1.12\times10^{-8}$d/cycle and $-$1.456$\times$10$^{-9}$d/cycle for T LMi and RW Mon, respectively. Such a large rate is impossibly explained by angular momentum loss and mass loss due to magnetic stellar winds. The sudden jumps in the orbital periods of both stars might be caused by a rapid mass exchange between the circumstellar matter and binaries. At last, the evolutionary trend of the two Algol-type systems, whose periods decreased continuously, is discussed. Their evolutionary outcome might be W UMa stars.
Effects of Compton Scattering on the Gamma-Ray Spectra of Solar Flares
Authors: Kotoku Jun’ichi , Makishima Kazuo , Matsumoto Yukari , Kohama Mitsuhiro , Terada Yukikatsu , Tamagawa Toru 
Published: March 2014

Abstract
Using the fully relativistic GEANT4 simulation toolkit, Monte Carlo simulation was applied to the transport of energetic electrons generated in solar flares, and resultant bremsstrahlung gamma-ray spectra were calculated. The solar atmosphere was approximated by 10 vertically stacked zones. The simulation took into account two important physical processes: that the bremsstrahlung photons emitted by precipitating relativistic electrons are strongly forward beamed toward the photosphere, and that the majority of these gamma-rays must be Compton backscattered by the solar atmosphere in order to reach the observer. Then, the Compton degradation was found to make the observable gamma-ray spectra much softer than predicted by simple analytic calculations. The gamma-ray signals were found to be enhanced by several conditions, including a broad pitch-angle distribution of the electrons, a near-limb flare longitude, and a significant tilt in the magnetic field lines if the flare longitude is rather small. These results successfully explain several important flare properties observed in the range of hard X-ray to gamma-ray, in particular including those obtained with Yohkoh. A comparison of the Yohkoh spectrum, from a GOES X3.7 class limb flare on 1998 November 22, with a simulation assuming a broad electron pitch-angle distribution suggests that gamma-rays from this particular solar flare were a mixture of direct bremsstrahlung photons and their Comptonization.
Apparent Photosphere of Massive Accretion-Disk Winds
Authors: Nishiyama Shinji , Watarai Ken-ya , Fukue Jun 
Published: March 2014

Abstract
We examined the observational appearance of highly optically thick winds from supercritical accretion disks, while especially focusing on the shape of a “photosphere” of the wind. When a massive wind blows from an accretion disk, the optical depth of the wind may exceed unity in the place, which is higher than the scale height of the disk. If such a wind is realized, the observed light may have originated from the photosphere of the wind, rather than from the disk surface. We calculated the apparent surface of the photosphere, where the observed optical depth is unity, and compared it with the geometry of the accretion disk. We found that the wind photosphere can expand over the disk scale-height for super-Eddington mass-loss rates, but the location and appearance of the photosphere strongly depend on the inclination angle as well as the mass-loss rate. This fact may affect on the interpretation of light curves in galactic eclipsing binaries and recently well-observed ultraluminous X-ray sources.
Monte Carlo Simulator and Ancillary Response Generator of Suzaku XRT/XIS System for Spatially Extended Source Analysis
Authors: Ishisaki Yoshitaka , Maeda Yoshitomo , Fujimoto Ryuichi , Ozaki Masanobu , Ebisawa Ken , Takahashi Tadayuki , Ueda Yoshihiro , Ogasaka Yasushi , Ptak Andrew , Mukai Koji , Hamaguchi Kenji , Hirayama Masaharu , Kotani Taro , Kubo Hidetoshi , Shibata Ryo , Ebara Masatoshi , Furuzawa Akihiro , Iizuka Ryo , Inoue Hirohiko , Mori Hideyuki , Okada Shunsaku , Yokoyama Yushi , Matsumoto Hironori , Nakajima Hiroshi , Yamaguchi Hiroya , Anabuki Naohisa , Tawa Noriaki , Nagai Masaaki , Katsuda Satoru , Hayashida Kiyoshi , Bamba Aya , Miller Eric D. , Sato Kosuke , Yamasaki Noriko Y. 
Published: March 2014

Abstract
We have developed a framework for the Monte Carlo simulations of X-Ray Telescope (XRT) and X-ray Imaging Spectrometer (XIS) on board Suzaku, mainly for the scientific analysis of spatially and spectroscopically complex celestial sources. A photon-by-photon instrumental simulator is built on the ANL platform, which has been successfully used in ASCA data analysis. The simulator has a modular structure, in which the XRT simulation is based on a ray-tracing library, while the XIS simulation utilizes a spectral “Redistribution Matrix File” (RMF), generated separately by other tools. Instrumental characteristics and calibration results [e.g., XRT geometry, reflectivity, mutual alignments, thermal shield transmission, build-up of the contamination on the XIS optical blocking filters (OBF)] are incorporated as completely as possible. Most of this information is available in the form of FITS (Flexible Image Transport System) files in the standard calibration database (CALDB). This simulator can also be utilized to generate an “Ancillary Response File” (ARF), which describes the XRT response and the amount of OBF contamination. An ARF is dependent on the spatial distribution of the celestial target and the photon accumulation region on the detector, as well as the observing conditions, such as the observation date and satellite attitude. We describe the principles of the simulator and the ARF generator, and demonstrate their performance compared with in-flight data.
A Suzaku Observation of the Low-Ionization Fe-Line Emission from RCW 86
Authors: Ueno Masaru , Sato Rie , Kataoka Jun , Bamba Aya , Harrus Ilana , Hiraga Junko , Hughes John P. , Kilbourne Caroline A. , Koyama Katsuji , Kokubun Motohide , Nakajima Hiroshi , Ozaki Masanobu , Petre Robert , Takahashi Tadayuki , Tanaka Takaaki , Tomida Hiroshi , Yamaguchi Hiroya 
Published: March 2014

Abstract
The newly operational X-ray satellite Suzaku observed the southwestern quadrant of the supernova remnant RCW 86 in 2006 February to study the nature of the 6.4 keV emission line first detected with the Advanced Satellite for Cosmology and Astronomy (ASCA). The new data confirm the existence of the line, localizing it for the first time; most of the line emission is adjacent and interior to the forward shock, and not at the locus of the continuum hard emission. We also report the first detection of a 7.1 keV line, which we interpret as $\mathrm{K}\beta$ emission from low-ionization iron. The Fe K line features are consistent with a non-equilibrium plasma of Fe-rich ejecta with $n_{\mathrm{e}} \, t \lesssim 10^{9} \,\mathrm{cm}^{-3} \,\mathrm{s}$ and $kT_{\mathrm{e}} \sim 5 \,\mathrm{keV}$. This combination of low $n_{\mathrm{e}} \, t$ and high $k T_{\mathrm{e}}$ suggests collisionless electron heating in an SNR shock. The Fe $\mathrm{K}\alpha$ line shows evidence for intrinsic broadening, with a width of 47 (34–59) eV (99% error region). The difference in the spatial distributions of the hard continuum above 3 keV and the Fe K line emission supports a synchrotron origin for the hard continuum.
An Apparent Hard X-Ray Decline of CH Cygni
Authors: Mukai Koji , Ishida Manabu , Kilbourne Caroline , Mori Hideyuki , Terada Yukikatsu , Chan Kai-Wing , Soong Yang 
Published: March 2014

Abstract
CH Cygni is a symbiotic star consisting of an M giant and an accreting white dwarf, which is known to be a highly variable X-ray source with a complex, two-component, spectra. Here, we report on two Suzaku observations of CH Cyg, taken in 2006 January and May, during which the system was seen to be in a soft X-ray bright, hard X-ray faint state. Based on the extraordinary strength of the 6.4 keV fluorescent Fe $\mathrm{K}\alpha$ line, we show that the hard X-rays observed with Suzaku are dominated by scattering.
Suzaku Discovery of Iron Absorption Lines in Outburst Spectra of the X-Ray Transient 4U 1630—472
Authors: Kubota Aya , Dotani Tadayasu , Cottam Jean , Kotani Taro , Done Chris , Ueda Yoshihiro , Fabian Andrew C. , Yasuda Tomonori , Takahashi Hiromitsu , Fukazawa Yasushi , Yamaoka Kazutaka , Makishima Kazuo , Yamada Shinya , Kohmura Takayoshi , Angelini Lorella 
Published: March 2014

Abstract
We present the results of six Suzaku observations of the recurrent black hole transient 4U 1630$-$472 during its decline from outburst from February 8 to March 23 in 2006. All observations show the typical high/soft state spectral shape in the 2–50 keV band, roughly described by an optically thick-disk spectrum in the soft energy band plus a weak power-law tail that becomes dominant only above $\sim 20 \,\mathrm{keV}$. The disk temperature decreases from 1.4 keV to 1.2 keV as the flux decreases by a factor of 2, consistent with a constant radius, as expected for disk-dominated spectra. All of the observations reveal significant absorption lines from highly ionized (H-like and He-like) iron $\mathrm{K}\alpha$’s at 7.0 keV and 6.7 keV. The energies of these absorption lines suggest a blue shift with an outflow velocity of $\sim 1000 \,\mathrm{km} \,\mathrm{s}^{-1}$. The H-like iron $\mathrm{K}\alpha$ equivalent width remains approximately constant at $\sim 30 \,\mathrm{eV}$ over all of the observations, while that of the He-like $\mathrm{K}\alpha$ line increases from 7 eV to 20 eV. Thus, the ionization state of the material decreases, as expected from the decline in flux. By fitting the profile with Voigt functions (curve of growth) together with detailed photo-ionization calculations, the total absorbing column, and the ionization parameter were estimated to be $(1.0 \hbox{--} 0.7) \times 10^{23} \,\mathrm{cm}^{-2}$ and $(6 \hbox{--} 4) \times 10^4$, respectively, for a velocity dispersion of $500 \,\mathrm{km} \,\mathrm{s}^{-1}$. This in turn constrains the size of the plasma to be $\sim 10^{10} \,\mathrm{cm}$, assuming a source distance of 10 kpc.
Suzaku Observations of the Hard X-Ray Variability of MCG −6–30–15: the Effects of Strong Gravity around a Kerr Black Hole
Authors: Miniutti Giovanni , Fabian Andrew C. , Anabuki Naohisa , Crummy Jamie , Fukazawa Yasushi , Gallo Luigi , Haba Yoshito , Hayashida Kiyoshi , Holt Steve , Kunieda Hideyo , Larsson Josefin , Markowitz Alex , Matsumoto Chiho , Ohno Masanori , Reeves James N. , Takahashi Tadayuki , Tanaka Yasuo , Terashima Yuichi , Torii Ken’ichi , Ueda Yoshihiro , Ushio Masayoshi , Watanabe Shin , Yamauchi Makoto , Yaqoob Tahir 
Published: March 2014

Abstract
Suzaku has, for the first time, enabled the hard X-ray variability of the Seyfert 1 galaxy MCG $-$6–30–15 to be measured. The variability in the 14–45 keV band, which is dominated by a strong reflection hump, is quenched relative to that at a few keV. This directly demonstrates that the whole reflection spectrum is much less variable than the power-law continuum. The broadband spectral variability can be decomposed into two components—a highly variable power-law and constant reflection—as previously inferred from other observations in the 2–10 keV band. The strong reflection and high iron abundance give rise to a strong broad iron line, which requires the inner disc radius to be at about 2 gravitational radii. Our results are consistent with the predictions of the light bending model which invokes the very strong gravitational effects expected very close to a rapidly spinning black hole.
Search for Oxygen Emission from Warm-Hot Intergalactic Medium around A2218 with Suzaku
Authors: Takei Yoh , Ohashi Takaya , Henry J. Patrick , Mitsuda Kazuhisa , Fujimoto Ryuichi , Tamura Takayuki , Yamasaki Noriko Y. , Hayashida Kiyoshi , Tawa Noriaki , Matsushita Kyoko , Bautz Mark W. , Hughes John P. , Madejski Grzegorz M. , Kelley Richard L. , Arnaud Keith A. 
Published: March 2014

Abstract
We searched for redshifted O emission lines from a possible warm-hot intergalactic medium (WHIM) surrounding the cluster of galaxies A2218 at $z=0.1756$ using the X-ray Imaging Spectrometer (XIS) instrument on Suzaku. This cluster is thought to have an elongated structure along the line of sight based on previous studies. We studied systematic uncertainties in the spectrum of the Galactic emission and in the soft X-ray response of the detectors due to the contamination building up on the XIS filters. We detected no significant redshifted O lines, and set a tight constraint on the intensity with upper limits for the surface brightness of O VII and O VIII lines of $1.1 \times 10^{-7}$ and $3.0 \times 10^{-7} \;\mathrm{photons} \;\mathrm{cm}^{-2} \,\mathrm{s}^{-1} \,\mathrm{arcmin}^{-2}$, respectively. These upper limits are significantly lower than the previously reported fluxes from the WHIM around other clusters of galaxies. We also discuss the prospect for detecting the WHIM lines with the Suzaku XIS in the future.
Suzaku Observations of the Centaurus Cluster: Absence of Bulk Motions in the Intracluster Medium
Authors: Ota Naomi , Fukazawa Yasushi , Fabian Andrew C. , Kanemaru Takehiro , Kawaharada Madoka , Kawano Naomi , Kelley Richard L. , Kitaguchi Takao , Makishima Kazuo , Matsushita Kyoko , Murase Kouichi , Nakazawa Kazuhiro , Ohashi Takaya , Sanders Jeremy S. , Tamura Takayuki , Urata Yuji 
Published: March 2014

Abstract
The Centaurus cluster ($z=0.0104$) was observed with the X-ray Imaging Spectrometer (XIS) onboard the Suzaku X-ray satellite in three pointings, one centered on the cluster core and the other two offset by $\pm 8 {{}^{\prime }}$ in declination. To search for possible bulk motions of the intracluster medium, the central energy of a He-like Fe K line (at a rest-frame energy of 6.7 kev) was examined to look for a positional dependence. Over spatial scales of 50 kpc to 140 kpc around the cluster core, the central line energy was found to be constant within a calibration error of 15 eV. The 90% upper limit on the line-of-sight velocity difference is $\vert\Delta v\vert &lt; 1400 \,\mathrm{km} \,\mathrm{s}^{-1}$, giving a tighter constraint than previous measurements. The significant velocity gradients inferred from a previous Chandra study were not detected between two pairs of rectangular regions near the cluster core. These results suggest that the bulk velocity does not largely exceed the thermal velocity of the gas in the central region of the Centaurus cluster. The mean redshift of the intracluster medium was determined to be 0.0097, in agreement with the optical redshift of the cluster within the calibration uncertainty. Implications of the present results for estimating the cluster mass are briefly discussed.
The Infrared Astronomical Mission AKARI
Authors: Murakami Hiroshi , Baba Hajime , Barthel Peter , Clements David L. , Cohen Martin , Doi Yasuo , Enya Keigo , Figueredo Elysandra , Fujishiro Naofumi , Fujiwara Hideaki , Fujiwara Mikio , Garcia-Lario Pedro , Goto Tomotsugu , Hasegawa Sunao , Hibi Yasunori , Hirao Takanori , Hiromoto Norihisa , Hong Seung Soo , Imai Koji , Ishigaki Miho , Ishiguro Masateru , Ishihara Daisuke , Ita Yoshifusa , Jeong Woong-Seob , Jeong Kyung Sook , Kaneda Hidehiro , Kataza Hirokazu , Kawada Mitsunobu , Kawai Toshihide , Kawamura Akiko , Kessler Martin F. , Kester Do , Kii Tsuneo , Kim Dong Chan , Kim Woojung , Kobayashi Hisato , Koo Bon Chul , Kwon Suk Minn , Lee Hyung Mok , Lorente Rosario , Makiuti Sin’itirou , Matsuhara Hideo , Matsumoto Toshio , Matsuo Hiroshi , Matsuura Shuji , MÜller Thomas G. , Murakami Noriko , Nagata Hirohisa , Nakagawa Takao , Naoi Takahiro , Narita Masanao , Noda Manabu , Oh Sang Hoon , Ohnishi Akira , Ohyama Youichi , Okada Yoko , Okuda Haruyuki , Oliver Sebastian , Onaka Takashi , Ootsubo Takafumi , Oyabu Shinki , Pak Soojong , Park Yong-Sun , Pearson Chris P. , Rowan-Robinson Michael , Saito Toshinobu , Sakon Itsuki , Salama Alberto , Sato Shinji , Savage Richard S. , Serjeant Stephen , Shibai Hiroshi , Shirahata Mai , Sohn Jungjoo , Suzuki Toyoaki , Takagi Toshinobu , Takahashi Hidenori , TanabÉ Toshihiko , Takeuchi Tsutomu T. , Takita Satoshi , Thomson Matthew , Uemizu Kazunori , Ueno Munetaka , Usui Fumihiko , Verdugo Eva , Wada Takehiko , Wang Lingyu , Watabe Toyoki , Watarai Hidenori , White Glenn J. , Yamamura Issei , Yamauchi Chisato , Yasuda Akiko 
Published: March 2014

Abstract
AKARI, the first Japanese satellite dedicated to infrared astronomy, was launched on 2006 February 21, and started observations in May of the same year. AKARI has a 68.5 cm cooled telescope, together with two focal-plane instruments, which survey the sky in six wavelength bands from mid–to far-infrared. The instruments also have a capability for imaging and spectroscopy in the wavelength range 2-180$\mu$m in the pointed observation mode, occasionally inserted into a continuous survey operation. The in-orbit cryogen lifetime is expected to be one and a half years. The All-Sky Survey will cover more than 90% of the whole sky with a higher spatial resolution and a wider wavelength coverage than that of the previous IRAS all-sky survey. Point-source catalogues of the All-Sky Survey will be released to the astronomical community. Pointed observations will be used for deep surveys of selected sky areas and systematic observations of important astronomical targets. These will become an additional future heritage of this mission.
The Far-Infrared Properties of Spatially Resolved AKARI Observations
Authors: Jeong Woong-Seob , Nakagawa Takao , Yamamura Issei , Pearson Chris P. , Savage Richard S. , Lee Hyung Mok , Shibai Hiroshi , Makiuti Sin’itirou , Baba Hajime , Barthel Peter , Clements Dave , Doi Yasuo , Figueredo Elysandra , Goto Tomotsugu , Hasegawa Sunao , Kaneda Hidehiro , Kawada Mitsunobu , Kawamura Akiko , Kester Do , Kwon Suk Minn , Matsuhara Hideo , Matsuura Shuji , Murakami Hiroshi , Oh Sang Hoon , Oliver Sebastian , Pak Soojong , Park Yong-Sun , Serjeant Stephen , Shirahata Mai , Sohn Jungjoo , Takagi Toshinobu , Wang Lingyu , White Glenn J. , Yamauchi Chisato 
Published: March 2014

Abstract
We present spatially resolved observations of IRAS sources from the Japanese infrared astronomy satellite AKARI All-Sky Survey during the performance verification phase of the mission. We extracted reliable point sources matched with the IRAS point source catalogue. By comparing IRAS and AKARI fluxes, we found that the flux measurements of some IRAS sources could have been over or underestimated, and affected by the local background, rather than the global background. We also found possible candidates for new AKARI sources and confirmed that AKARI observations resolved IRAS sources into multiple sources. All-Sky Survey observations are expected to verify the accuracies of IRAS flux measurements and to find new extragalactic point sources.
Nature of Infrared Sources in 11 $\mu $m Selected Sample from Early Data of the AKARI North Ecliptic Pole Deep Survey
Authors: Lee Hyung Mok , Im Myungshin , Wada Takehiko , Shim Hyunjin , Kim Seong Jin , Lee Myung Gyoon , Hwang Narae , Matsuhara Hideo , Nakagawa Takao , Oyabu Shinki , Pearson Chris P. , Takagi Toshinobu , Onaka Takashi , Fujishiro Naofumi , Hanami Hitoshi , Ishihara Daisuke , Ita Yoshifusa , Kataza Hirokazu , Kim Woojung , Matusmoto Toshio , Murakami Hiroshi , Ohyama Youichi , Sakon Itsuki , Tanabé Toshihiko , Uemizu Kazunori , Ueno Munetaka , Usui Fumihiko , Watarai Hidenori 
Published: March 2014

Abstract
We present the properties of 11 $\mu $m selected sources detected in the early data of the North Ecliptic Pole Deep (NEP-Deep) Survey of AKARI. The data set covers 6 wavelength bands from 2.5 to 11 $\mu $m, with exposure times of 10–20 minutes. This field lies within the CFHT survey with four filter bands ($g^\prime, r^\prime, i^\prime, z^\prime$), enabling us to establish nearly continuous spectral energy distributions (SEDs) for wavelengths ranging from 0.4 to 11 $\mu $m. The main sample studied here consists of 72 sources whose 11 $\mu $m AB magnitudes are equal to or brighter than 18.5 (144 $\mu $Jy), which is complete to more than 90%. The 11 $\mu $m band has an advantage of sampling star-forming galaxies with low-to-medium redshifts, since the prominent PAH feature shifts into this band. As expected, we find that the majority (71%) of 11 $\mu $m bright sources are star-forming galaxies at $0.2 \lesssim z \lesssim 0.7$ with $L_{\rm IR} \sim 10^{10}-10^{12}~L_{\odot}$ based on detailed modelling of the SEDs. We also find four AGNs lying at various redshifts in the main sample. In addition, we discuss a few sources that have non-typical SEDs of the main sample, including a brown-dwarf candidate, a steep power-law source, a flat-spectrum object, and an early-type galaxy at moderate redshift.
The Analysis of Penumbral Fine Structure Using an Advanced Inversion Technique
Authors: Jurčák Jan , Bellot Rubio Luis , Ichimoto Kiyoshi , Katsukawa Yukio , Lites Bruce , Nagata Shin’ichi , Shimizu Toshifumi , Suematsu Yoshinori , Tarbell Theodore D. , Title Alan M. , Tsuneta Saku 
Published: March 2014

Abstract
We present a method to study the penumbral fine structure using data obtained by the spectropolarimeter on board Hinode. For the first time, the penumbral filaments can be considered as being resolved in spectropolarimetric measurements. This enables us to use inversion codes with only one-component model atmospheres, and thus to assign the obtained stratifications of the plasma parameters directly to the penumbral fine structure. This approach was applied to the limb-side part of the penumbra in the active region NOAA10923. Preliminary results show a clear dependence of the plasma parameters on the continuum intensity in the inner penumbra, i.e., a weaker and horizontal magnetic field along with an increased line-of-sight velocity are found in the low layers of the bright filaments. The results in the mid penumbra are ambiguous, and future analyses are necessary to unveil the magnetic field structure and other plasma parameters there.