bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suzaku Observation of the Unidentified Very High Energy Gamma-Ray Source HESS J1702−420
Authors: Fujinaga Takahisa , Bamba Aya , Dotani Tadayasu , Ozaki Masanobu , PÜhlhofer Gerd , Wagner Stefan , Reimer Olaf , Funk Stefan , Hinton Jim 
Published: March 2014

Abstract
A deep X-ray observation of the unidentified very high energy (VHE) gamma-ray source HESS J1702 $-$ 420, for the first time, was carried out by Suzaku. No bright sources were detected in the XIS field of view (FOV), except for two faint point-like sources. The two sources, however, are considered not to be related to HESS J1702 $-$ 420, because their fluxes in the 2–10 keV band ( $\sim\ $ 10 $^{-14}\ $ erg s $^{-1}\ $ cm $^{-2}$ ) are $\sim\ $ 3 orders of magnitude smaller than the VHE gamma-ray flux in the 1–10 TeV band ( $F_{\rm TeV}$$=$ 3.1 $\times$ 10 $^{-11}\ $ erg s $^{-1}\ $ cm $^{-2}$ ). We compared the energy spectrum of diffuse emission, extracted from the entire XIS FOV with those from nearby observations. If we consider the systematic error of background subtraction, no significant diffuse emission was detected with an upper limit of $F_{\rm X}$$&lt;$ 2.7 $\times$ 10 $^{-12}\ $ erg s $^{-1}\ $ cm $^{-2}$ in the 2–10 keV band for an assumed power-law spectrum of $\Gamma$$=$ 2.1 and a source size same as that in the VHE band. The upper limit of the X-ray flux is twelve-times as small as the VHE gamma-ray flux. The large flux ratio ( $F_{\rm TeV}/F_{\rm X}$ ) indicates that HESS J1702 $-$ 420 is another example of a “dark” particle accelerator. If we use a simple one-zone leptonic model, in which VHE gamma-rays are produced through inverse Compton scattering of the cosmic microwave background and interstellar far-infrared emission, and the X-rays via the synchrotron mechanism, an upper limit of the magnetic field (1.7 $\ \mu$ G) is obtained from the flux ratio. Because the magnetic field is weaker than the typical value in the galactic plane (3–10 $\ \mu$ G), the simple one-zone model may not work for HESS J1702 $-$ 420 and a significant fraction of the VHE gamma-rays may originate from protons.
Global Distribution of Fe Kα Lines in the Galactic Center Region Observed with the Suzaku Satellite
Authors: Uchiyama Hideki , Nobukawa Masayoshi , Tsuru Takeshi Go , Koyama Katsuji , Matsumoto Hironori 
Published: March 2014

Abstract
We surveyed spatial profiles of the Fe K $\alpha $ lines in the Galactic center diffuse X-rays (GCDX), including the transient region from the GCDX to the Galactic ridge X-ray emission (GRXE), with the Suzaku satellite. We resolved Fe K $\alpha $ line complex into three lines of Fe I, Fe XXV, and Fe XXVI K $\alpha $ , and obtained their spatial intensity profiles with a resolution of $\sim\ $ 0 $^\circ\!\!\!.$ 1. We compared the Fe XXV K $\alpha $ profile with a stellar mass distribution (SMD) model made from near infrared observations. The intensity profile of Fe XXV K $\alpha $ was nicely fitted with the SMD model in the GRXE region, while that in the GCDX region showed a 3.8 $\ \pm\ $ 0.3 (0 $^\circ\!\!\!.$ 2 $&lt;$$\vert l\vert$$&lt;$ 1 $^\circ\!\!\!.$ 5) or 19 $\ \pm\ $ 6 ( $\vert l\vert$$&lt;$ 0 $^\circ\!\!\!.$ 2) times excess over the best-fit SMD model in the GRXE region. Thus, Fe XXV K $\alpha $ in the GCDX is hardly explained by the same origin of the GRXE. In the case of a point-source origin, a new population with the extremely strong Fe XXV K $\alpha $ line is required. An alternative possibility is that the majority of the GCDX is truly diffuse optically thin thermal plasma.
Suzaku Studies of Wide-Band Spectral Variability of the Bright Type I Seyfert Galaxy Markarian 509
Authors: Noda Hirofumi , Makishima Kazuo , Yamada Shin’ya , Torii Shunsuke , Sakurai Soki , Nakazawa Kazuhiro 
Published: March 2014

Abstract
The Type I Seyfert galaxy Markarian 509 was observed with Suzaku in 2010 November, for a gross time span of 2.2 days. The timing and spectral properties of the 0.5–45 keV X-rays, detected with the XIS and HXD, consistently revealed the presence of a soft spectral component that remained constant while the total X-ray intensity varied by $\pm$ 10%. This stable soft component, found in the 0.5–3.0 keV range, was interpreted as being a result of thermal Comptonization in a corona with a temperature of $\sim\ $ 0.5 keV and an optical depth of $\sim\ $ 18. The time-avearged 0.5–45 keV Suzaku spectrum was reproduced successfully, as a combination of this thermal Comptonization component, a harder power-law of photon index $\sim\ $ 1.8, moderate reflection, and an iron K-emission line. By analyzing four archival Suzaku datasets of the same object obtained in 2006, the thermal Comptonization component, which was stable during 2.2-day pointing in 2010, was found to vary on time scales of a few weeks, independently of the power-law component. Implications of these results are discussed in terms of a “multi-zone Comptonization” view, obtained with Suzaku from the black-hole binary Cygnus X-1.
Revisit of Local X-Ray Luminosity Function of Active Galactic Nuclei with the MAXI Extragalactic Survey
Authors: Ueda Yoshihiro , Hiroi Kazuo , Isobe Naoki , Hayashida Masaaki , Eguchi Satoshi , Sugizaki Mutsumi , Kawai Nobuyuki , Tsunemi Hiroshi , Mihara Tatehiro , Matsuoka Masaru , Ishikawa Masaki , Kimura Masashi , Kitayama Hiroki , Kohama Mitsuhiro , Matsumura Takanori , Morii Mikio , Nakagawa Yujin E. , Nakahira Satoshi , Nakajima Motoki , Negoro Hitoshi , Serino Motoko , Shidatsu Megumi , Sootome Tetsuya , Sugimori Kousuke , Suwa Fumitoshi , Toizumi Takahiro , Tomida Hiroshi , Tsuboi Yohko , Ueno Shiro , Usui Ryuichi , Yamamoto Takayuki , Yamaoka Kazutaka , Yamazaki Kyohei , Yoshida Atsumasa 
Published: March 2014

Abstract
We constructed a new X-ray (2–10 keV) luminosity function of Compton-thin active galactic nuclei (AGNs) in the local universe, using the first MAXI/GSC source catalog surveyed in the 4–10 keV band. The sample consists of 37 non-blazar AGNs at $z$$=$ 0.002–0.2, whose identification is highly ( $&gt;\ $ 97%) complete. We confirmed the trend that the fraction of absorbed AGNs with $N_{\rm H}$$&gt;\ $ 10 $^{22}$ cm $^{-2}$ rapidly decreases against the luminosity ( $L_{\rm X}$ ), from 0.73 $\ \pm\ $ 0.10 at $L_{\rm X}$$=$ 10 $^{42-43.5}$ erg s $^{-1}$ to 0.12 $\ \pm\ $ 0.08 at $L_{\rm X}$$=$ 10 $^{43.5-45.5}$ erg s $^{-1}$ . The obtained luminosity function was well-fitted with a smoothly connected double power-law model whose indices are $\gamma_1$$=$ 0.84 (fixed) and $\gamma_2$$=$ 2.0 $\ \pm\ $ 0.2 below and above the break luminosity, $L_{*}$$=$ 10 $^{43.3\pm0.4}$ erg s $^{-1}$ , respectively. While the result of the MAXI/GSC agrees well with that of HEAO-1 at $L_{\rm X}$$\gtrsim$ 10 $^{43.5}$ erg s $^{-1}$ , it gives a larger number density at the lower luminosity range. A comparison between our luminosity function in the 2–10 keV band and that in the 14–195 keV band obtained from the Swift/BAT survey indicates that the averaged broad-band spectra in the 2–200 keV band should depend on the luminosity, approximated by $\Gamma$$\sim$ 1.7 for $L_{\rm X}$$\lesssim$ 10 $^{44}$ erg s $^{-1}$ , while $\Gamma$$\sim$ 2.0 for $L_{\rm X}$$\gtrsim$ 10 $^{44}$ erg s $^{-1}$ . This trend was confirmed by the correlation between the luminosities in the 2–10 keV and 14–195 keV bands in our sample. We argue that there is no contradiction in the luminosity functions between above and below 10 keV once this effect is taken into account.
Suzaku Observations of Metal Distributions in the Intracluster Medium of the Centaurus Cluster
Authors: Sakuma Eri , Ota Naomi , Sato Kosuke , Sato Takuya , Matsushita Kyoko 
Published: March 2014

We report the first observations of metal distributions in the intracluster medium of the Centaurus cluster up to $\sim\ $ 0.17 $\ r_{180}$ with Suzaku. Radial profiles of the O, Mg, Si, S, Ar, Ca, and Fe were determined at the outer region of the cluster, and their variations appear to be similar to each other. Within the cool core region ( $r$ $&lt;$ 0.045 $\ r_{180}$ ), all of the metal distributions sharply increased toward the center. In the central region ( $r$ $&lt;$ 0.015 $\ r_{180}$ ), the abundances of Si, S, Ar, Ca, and Fe were 1.5–1.8 solar, while those of O and Mg were approximately 1 solar. The derived abundance ratios of O and Mg to Fe were slightly lower than those of a set of other clusters. In contrast, the calculated mass-to-light ratios (MLRs) for O, Mg, and Fe were larger than those of the other clusters. For the outer region of the cool core ( $r$ $&gt;$ 0.07 $\ r_{180}$ ), all of the abundances were almost constant at 0.5 solar. The derived MLRs were comparable to those of the other clusters. This suggests that the cD galaxy of the Centaurus cluster efficiently supplies more Fe than the other clusters.
Suzaku Observation of Nearby On-Going Merger Cluster Abell 3627
Authors: Nishino Sho , Fukazawa Yasushi , Hayashi Katsuhiro 
Published: March 2014

Abstract
We present the results of the Suzaku observation of a nearby (z $=$ 0.016), on-going merger cluster, Abell 3627. The overall temperature of the ICM is around 7 keV, and we found a cool region with $kT$$\sim$ 4–5 keV at the position corresponding to the brightness excess from a spherically symmetrical $\beta$-model found by ROSAT. This structure seems to be a subcluster colliding into the main body. In the temperature and density profiles, no apparent jump associated with a shock is confirmed at the colliding position; therefore, the velocity of the subcluster seems to be subsonic. On the other hand, the line-of-sight velocity of the subcluster is strictly restricted to be less than 800 km s$^{-1}$ using the Doppler shift of the Fe-K lines. Moreover, our ICM temperature map also suggests the possibility of another merging subcluster in the north-west region. A 3627 is now in the process of an aggressive cluster merger, associated with the formation of a large-scale structure.
Molecular and Atomic Gas toward HESS J1745−303 in the Galactic Center: Further Support for the Hadronic Scenario
Authors: Hayakawa Takahiro , Torii Kazufumi , Enokiya Rei , Amano Takanobu , Fukui Yasuo 
Published: March 2014

Abstract
We compared TeV $\gamma$-rays with new $^{12}$CO $J$$=$ 2–1 data toward HESS J1745$-$303 in the Galactic center, and confirmed that the molecular cloud MG358.9$-$0.5 toward ($l$, $b$) $=$ (358$^\circ\!\!\!.$9, $-$0$^\circ\!\!\!.$5) at $V_\mathrm{LSR}$$=$$-$100–0 km s$^{-1}$ shows a reasonable positional agreement with the primary peak (northern part) of the $\gamma$-ray source. For the southern part of HESS J1745$-$303, we have seen no CO counterpart, whereas H I gas in the SGPS H I dataset shows a possible counterpart to the $\gamma$-ray source. This H I gas may be optically thick, as supported by the H I line shape similar to the optically thick $^{12}$CO. We estimate the total mass of interstellar protons including both the molecular and atomic gas to be 2 $\times$ 10$^{6}M\odot$ and the cosmic-ray proton energy to be 6 $\times$ 10$^{48}\ $erg in the hadronic scenario. We discuss possible origins of the cosmic-ray protons including the nearby SNR G359.1$-$0.5. The SNR may be able to explain the northern $\gamma$-ray source, but the southern source seems to be too far to be energized by the SNR. As an alternative, we argue that the second-order Fermi acceleration in the inter-clump space surrounded by randomly moving high-velocity clumps may offer a possible mechanism to accelerate protons across the entire HESS source. The large turbulent motion with a velocity dispersion of $\sim\ $15 km s$^{-1}$ has an energy density two orders of magnitude higher than in the solar vicinity, and is viable as the energy source.
Distance and Reddening of the Isolated Dwarf Irregular Galaxy NGC 1156
Authors: Kim Sang Chul , Park Hong Soo , Kyeong Jaemann , Lee Joon Hyeop , Ree Chang Hee , Kim Minjin 
Published: March 2014

We present a photometric estimation of the distance and reddening values to the dwarf irregular galaxy NGC 1156, that is one of the best targets for the study of isolated dwarf galaxies in the nearby universe. We used imaging data sets of the Hubble Space Telescope (HST) Advanced Camera for Surveys, High Resolution Channel of the central region of NGC 1156 (26$''$ $\times$ 29$''$) available in the HST archive for this study. From the ($U$ $-$ $B$, $B$ $-$ $V$) color–color diagram, we first estimated the total (foreground $+$ internal) reddening toward NGC 1156 of $E$($B$ $-$ $V$) $=$ 0.35$\ \pm\ $0.05 mag, whereas only the foreground reddening was previously known to be $E$($B$ $-$ $V$) $=$ 0.16 mag (1984, ApJS, 54, 33) or 0.24 mag (1998, ApJ, 500, 525). Based on the brightest-star method, selecting the three brightest blue supergiant (BSG) stars with a mean $B$ magnitude of $\langle B$(3$B$)$\rangle$ $=$ 21.94 and the three brightest red supergiant (RSG) stars with a mean $V$ magnitude of $\langle V$(3$R$)$\rangle$ $=$ 22.76, we derived the distance modulus to NGC 1156 to be ($m$ $-$ $M$)$_{0,{\rm BSG}}$ $=$ 29.16 mag and $(m-M)_{0,{\rm RSG}}$ $=$ 29.55 mag. By using weights of 1 for BSGs and 1.5 for RSGs, we finally obtained a weighted mean distance modulus to NGC 1156, $(m-M)_0$ $=$ 29.39$\ \pm\ $0.20 mag (distance $=$ 7.6$\ \pm\ $0.7 Mpc), which is in agreement with previous estimates. Combining the photometry data of this study with those of Karachentsev, Musella, and Grimardi (1996, A&A, 310, 722) gives a smaller distance to NGC 1156, which is discussed together with the limits of the data.
Digital Spectro-Correlator System for the Atacama Compact Array of the Atacama Large Millimeter/Submillimeter Array
Authors: Kamazaki Takeshi , Okumura Sachiko K. , Chikada Yoshihiro , Okuda Takeshi , Kurono Yasutaka , Iguchi Satoru , Mitsuishi Shunji , Murakami Yuji , Nishimuta Naomitsu , Mita Haruo , Sano Ryo 
Published: March 2014

Abstract
We have developed an FX-architecture digital spectro-correlator for the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array. The correlator is able to simultaneously process four pairs of dual polarization signals with a bandwidth of 2 GHz, which are received by up to sixteen antennas. It can calculate auto- and cross-correlation spectra, including cross-polarization in all combinations of all the antennas, and output correlation spectra with flexible spectral configuration, such as multiple frequency ranges and multiple frequency resolutions. Its spectral dynamic range is estimated to be higher than 10$^{4}$ relative to $T_{\rm sys}$ from processing results of thermal noise for eight hours with a typical correlator configuration. The sensitivity loss is also confirmed to be 0.9% with the same configuration. In this paper, we report on the detailed design of the correlator and the verification results of the developed hardware.
A Study on the Correlations between Diffuse Interstellar Bands
Authors: Xiang Fuyuan , Liu Zhou , Yang Xuejuan 
Published: March 2014

Abstract
Correlations between diffuse interstellar band equivalent widths (EWs) were sought, using a database of 45 prominent diffuse interstellar bands (DIBs) and seven $ C_{2}$ bands in 278 sightlines collected from the literature. We found that 11 pairs of DIBs ($ \lambda\ $ 5544/5797 Å, $ \lambda\ $ 5544/6196 Å, $ \lambda\ $ 5544/6614 Å, $ \lambda\ $ 5809/6196 Å, $ \lambda\ $ 5809/6203 Å, $ \lambda\ $ 5809/6270 Å, $ \lambda\ $ 5809/6614 Å, $ \lambda\ $ 6196/6614 Å, $ \lambda\ $ 6196/6699 Å, $ \lambda\ $ 6203/6284 Å, and $ \lambda\ $ 6270/6699 Å) show a strong correlation with high coefficient ($ R$$ \geq$ 0.95), 416 pairs show a good correlation (0.7 $ \leq$$ R$$ \lt$ 0.95) and 358 pairs show a poor correlation ($ R$$ \lt$ 0.7). According to the values of the correlation coefficients and the spectroscopic features, we divided some of the 45 prominent DIBs into two isolated families.
Subaru Constraint on Circular Polarization in I-Band Emission from the Magnetar 4U 0142+61
Authors: Wang Zhongxiang , Tanaka Yasuyuki T. , Zhong Jing 
Published: March 2014

Abstract
We present the first imaging circular polarimetry of the anomalous X-ray pulsar (AXP) 4U 0142$+$61 at optical wavelengths. The AXP is the only magnetar that has been well studied at optical and infrared wavelengths, and is known to have a complicated broad-band spectrum over the wavelength range. The optical polarimetric observation was carried out with the 8.2-m Subaru telescope at the $I$-band. From the observation, the degree of circular polarization, $V$, was measured to be $V$ $=$ 1.1$ \pm $2.0%, or $\vert V\vert$ $\leq$ 4.3% (90% confidence). The relatively large uncertainty was due to the faintness of the source ($I$ $=$ 23.4–24.0). Considering the currently suggested models for optical emission from magnetars, our result is not sufficiently conclusive to discriminate the models. We suggest that because linear polarization is expected to be strong in the models, linear polarimetry of this magnetar should be conducted.
The Active Contact Binary FU Draconis: Four Color Light Curves and Period Changes
Authors: Liang Liu , Sheng-Bang Qian , Jia-Jia He , Wen-Ping Liao , Li-Ying Zhu , Ergang Zhao 
Published: March 2014

Abstract
Secured four color light curves of FU Dra were analyzed with the 2003 version of the Wilson and Devinney (WD) code. It was shown that FU Dra is still a W-type contact binary system, but might have a high fill-out factor ($f$$=$ 26.7% $\pm$ 1.0%). A dark spot was introduced on the massive cool component. A period investigation based on all available data shows that the period of the system may include a long-term increase ($dP/dt$$=$ 8.8 $\pm$ 2.9 $\times$ 10$^{-8}$ d yr$^{-1}$) and an oscillation (semi-amplitude of 0.0024 d, $P_3$$=$ 7.8 yr). The long-term period decrease may be caused by mass transfer, though the periodic oscillation may be rooted in cyclic magnetic activity.
Peculiar Black-Hole Unipolar Induction
Authors: Okamoto Isao 
Published: March 2014

It is argued that a posteriori without conflicting with the dubbed no-hair theorem, a Kerr black hole acquires its own proper magnetosphere in the steady eigen-state. The angular frequency of field lines, $ {\Omega_{\rm F}}$ , given as the eigenvalue in terms of the hole’s angular frequency, $ {\Omega_{\rm H}}$ , couples with the frame-dragging angular frequency, $ \omega$ , to create an inner general-relativistic domain of $ {\Omega_{\rm H}} \gt \omega$ $ \gt {\Omega_{\rm F}}$ , in which the gradient of the electric potential is, when viewed by the fiducial observers (FIDOs), reversed in direction from that in the outer quasi-classical domain of $ {\Omega_{\rm F}} \gt \omega$ $ \gt$ 0. The field lines are pinned down in the plasma source at the interface between the two domains (upper null surface S$ _{\rm N}$ ), from which pair-particles well up, charge-separated into the ingoing and outgoing winds. The EMFs due to unipolar induction operate to drive the surface currents, following Ohm’s law, on the resistive membranes terminating the force-free domains (say, S$ _{\rm ffH}$ and S$ _{{\rm ff}\infty}$ ), to exert the surface torques onto the respective membranes, thereby extracting angular momentum from the hole and transferring to the domain of astrophysical loads.
A Suzaku Study of Ejecta Structure and Origin of Hard X-Ray Emission in the Supernova Remnant G 156.2+5.7
Authors: Uchida Hiroyuki , Tsunemi Hiroshi , Katsuda Satoru , Mori Koji , Petre Robert , Yamaguchi Hiroya 
Published: March 2014

Abstract
We report on an X-ray study of the evolved Galactic supernova remnant (SNR) G 156.2$+$5.7 based on six pointing observations with Suzaku. The remnant’s large extent (100$'$ in diameter) allows us to investigate its radial structure in the northwestern and eastern directions from the apparent center. The X-ray spectra were well fit with a two-component non-equilibrium ionization model representing the swept-up interstellar medium (ISM) and the metal-rich ejecta. We found prominent central concentrations of Si, S, and Fe from the ejecta component; the lighter elements of O, Ne, and Mg were distributed more uniformly. The temperature of the ISM component suggests a slow shock ($\sim $610–960 km s$^{-1}$); hence, the remnant’s age is estimated to be $\sim $7000–15000 yr, assuming its distance to be $\sim $1.1 kpc. G 156.2$+$5.7 has also been thought to emit hard, non-thermal X-rays, despite being considerably older than any other such remnant. In response to a recent discovery of a background cluster of galaxies (2XMM J045637.2$+$522411), we carefully excluded its contribution, and reexamined the origin of the hard X-ray emission. We found that the residual hard X-ray emission is consistent with the expected level of the cosmic X-ray background. Thus, no robust evidence for non-thermal emission was obtained from G 156.2$+$5.7. These results are consistent with the picture of an evolved SNR.
Characterization of Dwarf Novae Using SDSS Colors
Authors: Kato Taichi , Maehara Hiroyuki , Uemura Makoto 
Published: March 2014

Abstract
We have developed a method for estimating the orbital periods of dwarf novae from the Sloan Digital Sky Survey (SDSS) colors in quiescence using an artificial neural network. For typical objects below the period gap with sufficient photometric accuracy, we were able to estimate the orbital periods with accuracy to a 1 $\sigma$ error of 22%. The error of the estimation is worse for systems with longer orbital periods. We have also developed a neural-network-based method for categorical classification. This method has proven to be efficient in classifying objects into three categories (WZ Sge type, SU UMa type, and SS Cyg/Z Cam type), and works for very faint objects to a limit of g$=$ 21 mag. Using this method, we have investigated the distribution of the orbital periods of dwarf novae from a modern transient survey (Catalina Real-Time Survey). Using a Bayesian analysis developed by Uemura et al. (2010, PASJ, 62, 613), we have found that the present sample tends to give a flatter distribution to the shortest period and a shorter estimate of the period minimum, which may have resulted from uncertainties in the neural-network analysis and photometric errors. We also provide estimated orbital periods, estimated classifications, and supplemental information on known dwarf novae with the quiescent SDSS photometry.
Image Slicer for the Subaru Telescope High Dispersion Spectrograph
Authors: Tajitsu Akito , Aoki Wako , Yamamuro Tomoyasu 
Published: March 2014

Abstract
We report on the design, manufacturing, and performance of the image slicer for the High Dispersion Spectrograph on Subaru Telescope. This instrument is a Bowen–Walraven type image slicer, providing five images of 0$.\!\!\!”$3 $\times$ 1$.\!\!\!”$5 with a resolving power of $R$$=$$\lambda/\delta \lambda$$=$ 110000. The resulting resolving power and line profiles have been investigated in detail, including estimates of the defocusing effect on the resolving power. The throughput in a wavelength range of from 400 to 700 nm is higher than 80%, thereby improving the efficiency of the spectrograph under a seeing condition of 0$.\!\!\!”$7 by a factor of 1.8.