bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suzaku Observation of G359.79$-$0.26, a New Supernova Remnant Candidate in the Galactic Center
Authors: Mori Hideyuki , Tsuru Takeshi Go , Hyodo Yoshiaki , Koyama Katsuji , Senda Atsushi 
Published: March 2014

Abstract
Utilizing Suzaku observations, we obtained the X-ray spectrum of G359.79$-$0.26, an extended X-ray feature nearby the Galactic center (GC) supernova remnant (SNR) SgrA East. We estimated the contribution from the Galactic center diffuse X-rays, which allows us a proper background subtraction from the faint extended source. A thin thermal plasma with a temperature of $ kT_{\rm e} \sim 1$keV and slightly enhanced metal abundances (S and Ar) are required to reproduce the G359.79$-$0.26 spectrum. The absorption column density ($N_{\rm H} \sim 4 \times 10^{22}$ cm$^{-2}$) associated with the plasma indicates that G359.79$-$0.26 is located in the GC. The thermal energy of the plasma is estimated to be $1.7 \times 10^{50}$erg, typical for galactic SNRs. Its center-filling X-ray emission surrounded by a shell-like radio structure suggests that G359.79$-$0.26 would be a new member of the mixed-morphology SNR class. The 2.45keV mosaic image covering a $\sim 40' \times 40'$ GC field implies an alternative possibility that G359.79$-$0.26 might be a part of a large ring-like structure with a size of $18' \times 16'$.
Spectral Properties of Prompt Emission of Four Short Gamma-Ray Bursts Observed by the Suzaku-WAM and the Konus-Wind
Authors: Ohno Masanori , Fukazawa Yasushi , Takahashi Takuya , Yamaoka Kazutaka , Sugita Satoshi , Pal'shin Valentin , Frederiks Dmitry , Oleynik Philipp , Ulanov Mikhail , Sakamoto Takanori , Sato Goro , Hurley Kevin , Tashiro Makoto S. , Urata Yuji , Onda Kaori , Tamagawa Toru , Terada Yukikatsu , Suzuki Motoko , Soojing Hong 
Published: March 2014

Abstract
We have performed a joint analysis of prompt emission from four bright short gamma-ray bursts (GRBs) with the Suzaku-WAM and the Konus-Wind experiments. This joint analysis allows us to investigate the spectral properties of short-duration bursts over a wider energy band with a higher accuracy. We find that these bursts have a high $E_{\rm peak}$, around 1MeV and have a harder power-law component than that of long GRBs. However, we can not determine whether these spectra follow the cut-off power-law model or the Band model.
We also investigated the spectral lag, hardness ratio, inferred isotropic radiation energy and existence of a soft emission hump, in order to classify them into short or long GRBs using several criteria, in addition to the burst duration. We find that all criteria, except for the existence of the soft hump, support the fact that our four GRBsamples are correctly classified as belonging to the short class. In addition, our broad-band analysis revealed that there is no evidence of GRBs with a very large hardness ratio, as seen in the BATSE short GRBsample, and that the spectral lag of our four short GRBs is consistent with zero, even in theMeV energy band, unlike long GRBs. Although our short GRBsamples are still limited, these results suggest that the spectral hardness of short GRBs might not differ significantly from that of long GRBs, and also that the spectral lag at high energies could be a strong criterion for burst classification.
AKARI IRC Survey of the Large Magellanic Cloud: Outline of the Survey and Initial Results
Authors: Ita Yoshifusa , Onaka Takashi , Kato Daisuke , TanabÉ Toshihiko , Sakon Itsuki , Kaneda Hidehiro , Kawamura Akiko , Shimonishi Takashi , Wada Takehiko , Usui Fumihiko , Koo Bon-Chul , Matsuura Mikako , Takahashi Hidenori , Nakada Yoshikazu , Hasegawa Tetsuo , Tamura Motohide 
Published: March 2014

Abstract
We observed an area of 10deg$^2$ of the Large Magellanic Cloud using the Infrared Camera (IRC) on board AKARI. The observations were carried out using five imaging filters (3, 7, 11, 15, and 24$\mu$m) and a dispersion prism (2-5$\mu$m, $\lambda / \Delta\lambda \sim$ 20) equipped in the IRC. This paper describes an outline of our survey project, and presents some initial results using imaging data that detected over 5.9$\times$10$^5$ near-infrared and 6.4$\times$10$^4$ mid-infrared point sources. The 10$\sigma$ detection limits of our survey are about 16.5, 14.0, 12.3, 10.8, and 9.2 in Vega-magnitude at 3, 7, 11, 15, and 24$\mu$m, respectively. The 11 and 15$\mu$m data, which are unique to AKARI IRC, allow us to construct color-magnitude diagrams that are useful to identify stars with circumstellar dust. We found a new sequence in the color-magnitude diagram, which is attributed to red giants with luminosity fainter than that of the tip of the first red-giant branch. We suggest that this sequence is likely to be related to the broad emission feature of aluminum oxide at 11.5$\mu$m. The 11 and 15$\mu$m data also indicate that the ([11]$-$[15]) color of both oxygen-rich and carbon-rich red giants once becomes blue, and then turns red again in the course of their evolution, probably due to a change in the flux ratio of the silicate or silicon carbide emission feature at 10 or 11.3$\mu$m to the 15$\mu$m flux.
On Period Variations of the K-Type Eclipsing Binary BM Ursae Majoris
Authors: Yang Yang-Gui , Wei J.-Y. , Nakajima Kazuhiro 
Published: March 2014

Abstract
From new CCD observations, 11 light minimum times are presented in this paper. The orbital period change of a W UMa-type eclipsing binary, BM Urase Majoris, was investigated, based on all available times of light minimum. It was discovered that the orbital period of the binary shows cyclic oscillation, superimposed on a secular period decrease. The amplitude and the period of the cyclic variation are $A$$=$ 0.0101($\pm$0.0004)d and $P_{3}$$=$ 30.8($\pm$0.2)yr, respectively. This kind of cyclic variation may be due to a light-time effect via an unseen third body. If the existence of an additional body is true, it may remove a great amount of angular momentum from the central system, and may play an important role in the formation of close binary. The orbital period continuously decreases at a rate of $dP/dt$$=$$-$7.49($\pm$0.16) $\times$ 10$^{-8}$dyr$^{-1}$, which may be due to mass transfer from the primary to the secondary, accompanying mass and angular-momentum loss from the binary system. The orbital period decrease, accompanying mass and angular momentum loss, would cause the contact degree to increase. Therefore, this binary will evolve into a deep contact configuration.
Analysis of the Spatial Distribution of Galaxies in the Numerical Galaxy Catalog
Authors: Ueda Haruhiko , Nagashima Masahiro , Yahagi Hideki 
Published: March 2014

Abstract
We examine the spatial distribution of galaxies in the Numerical Galaxy Catalog, which is based on a hierarchical clustering framework. This catalog is constructed from a semianalytic model of galaxy formation combined with high-resolution $N$-body simulations in a $\Lambda$-dominated flat cold dark-matter cosmological model. To quantify the spatial distribution of galaxies, we use a graph-theoretical approach, because it is one of the most powerful statistical ways of estimating spatial data. In particular, three types of graphs are adopted: the Delaunay graph, the minimal spanning tree, and the constellation graph. To quantify the galaxy distributions, we apply statistical measures suitable for each type. The mass distributions in the cold dark-matter universe are also examined to clarify differences in the spatial distribution of dark matter and galaxies. The spatial distribution of galaxies in the two-degree field (2dF) galaxy redshift survey is finally compared with that in the Numerical Galaxy Catalog. From our analysis, we definitely show that galaxy distributions in the Numerical Galaxy Catalog are different from the dark-matter distributions. We also find that the Numerical Galaxy Catalog considerably improves the theoretical prediction of spatial galaxy distributions, although it does not do enough to reproduce the 2dF galaxy redshift survey. Finally, we show that the constellation graph and the minimal spanning tree are convenient for quantifing the galaxy distributions in an objective manner.
Suzaku Results on the Obscured Low-Luminosity Active Galactic Nucleus in NGC 4258
Authors: Yamada Shin’ya , Itoh Takeshi , Makishima Kazuo , Nakazawa Kazuhiro 
Published: March 2014

Abstract
In 2006 June, the obscured low-luminosity active galactic nucleus in the nearby Seyfert 1.9 galaxy NGC 4258 was observed with Suzaku for $\sim$100 ks. Utilizing the XIS and the HXD, the nucleus emission was detected over a $\sim$2 to $\sim$40 keV range, with an unabsorbed 2–10 keV luminosity of $\sim$8 $\times$ 10$^{40}$ergs$^{-1}$; it varied by a factor of $\sim$2 during the observation. Its 2–40 keV spectrum is reproduced by a single power law with a photon index of $\Gamma$$\sim$ 2.0, absorbed by an equivalent hydrogen column of $\sim$1.0 $\times$ 10$^{23}$cm$^2$. The spectrum within $4{}^{\prime}$ of the nucleus also required a softer thin-thermal emission, as well as an intermediate hardness component, attributable to integrated point sources. A weak neutral Fe-K$\alpha$ florescence line was detected at an equivalent width of $\sim$40 eV. A cold reflection component was not required by the data, with the reflector solid angle $\Omega$ seen from the nucleus constrained as $\Omega /$2$\pi$$\lesssim$ 0.3, assuming a general case of 60$^\circ$ inclination. The results suggest that the cold reflecting material around the nucleus is localized along our line of sight, rather than forming a thick torus.
Hard X-Ray Properties of the Merging Cluster Abell 3667 as Observed with Suzaku
Authors: Nakazawa Kazuhiro , Sarazin Craig L. , Kawaharada Madoka , Kitaguchi Takao , Okuyama Sho , Makishima Kazuo , Kawano Naomi , Fukazawa Yasushi , Inoue Susumu , Takizawa Motokazu , Wik Daniel R. , Finoguenov Alexis , Clarke Tracy E. 
Published: March 2014

Abstract
Wide-band Suzaku data on the merging cluster Abell 3667 were examined for hard X-ray emission in excess to the known thermal component. Suzaku detected X-ray signals in a wide energy band from 0.5 to 40 keV. The hard X-ray ($\gt$10 keV) flux observed by the HXD around the cluster center cannot be explained by a simple extension of the thermal emission with an average temperature of $\sim$7 keV. The emission is most likely to be from a very hot ($kT$$\gt$ 13.2 keV) thermal component around the cluster center, produced via a strong heating process in a merger. In the north-west radio relic, no signature of non-thermal emission was observed. Using the HXD, the overall upper-limit flux within a 34$^\prime$$\times$ 34$^\prime$ field-of-view around the relic was derived to be 5.3 $\times$ 10$^{-12}$ergs$^{-1}$cm$^{-2}$ in the 10–40 keV band, after subtracting the ICM contribution estimated using the XIS or the XMM-Newton spectra. Directly on the relic region, the upper limit is further tightened by the XIS data to be less than 7.3 $\times$ 10$^{-13}$ergs$^{-1}$cm$^{-2}$, when converted into the 10–40 keV band. The latter value suggest that the average magnetic field within the relic is higher than 1.6 $\mu$G. The non-thermal pressure due to magnetic fields and relativistic electrons may be as large as $\sim$20% of the thermal pressure in the region.
Effects of Minor Mergers on the Coalescence of a Supermassive Black Hole Binary
Authors: Matsui Hidenori , Habe Asao 
Published: March 2014

Abstract
We studied the possibility that minor mergers can resolve the loss cone depletion problem, which is a difficulty that occurs in the coalescence process of a supermassive black hole (SMBH) binary, by performing numerical simulations with a highly accurate $N$-body code. We showed that a minor merger of a dwarf galaxy disturbs stellar orbits in the galactic central region of the host galaxy where loss cone depletion has already been caused by the SMBH binary. The disturbed stars are supplied into the loss cone. Stars of the dwarf galaxy are also supplied into the loss cone. The gravitational interactions between the SMBH binary and these stars become very effective. The gravitational interaction decreases the binding energy of the SMBH binary effectively. As a result, shrinking of the separation of the SMBH binary is accelerated. Our numerical results strongly suggest that minor mergers are one of the important processes to reduce the coalescence time of the SMBH binary to much less than the Hubble time.
A Search for Molecular Gas toward a BzK-Selected Star-Forming Galaxy at z = 2.044
Authors: Hatsukade Bunyo , Iono Daisuke , Motohara Kentaro , Nakanishi Kouichiro , Hayashi Masao , Shimasaku Kazuhiro , Nagao Tohru , Tamura Yoichi , Malkan Matthew A. , Ly Chun , Kohno Kotaro 
Published: March 2014

Abstract
We present a search for CO (3–2) emission in SDF-26821, a $BzK$-selected star-forming galaxy (sBzK) at $z$$=$ 2.044, using the 45-m telescope of the Nobeyama Radio Observatory and the Nobeyama Millimeter Array. We did not detect significant emission, and derived the 2$\sigma$ limits: CO luminosity of $L^\prime_{\rm {CO}}$ 3.1 $\times$ 10$^{10}$Kkms$^{-1}$pc$^{-2}$, ratio of far-infrared luminosity to CO luminosity of $L_{\rm {FIR}}/L^\prime_{\rm {CO}}$$&gt;$ 57 (Kkms$^{-1}$pc$^{2}$)$^{-1}$, and molecular gas mass of $M_{\rm {H_2}}$ 2.5 $\times$ 10$^{10}$, assuming a velocity width of 200 kms$^{-1}$ and a CO-to-H$_2$ conversion factor of $\alpha_{\rm {CO}}$$=$$0.8$ (Kkms$^{-1}$pc$^{2}$)$^{-1}$. The ratio $L_{\rm {FIR}}/L^\prime_{\rm {CO}}$, a measure of the star-formation efficiency (SFE), is comparable to, or higher than, the two $z$$\sim$ 1.5 sBzKs detected in CO (2-1) previously, suggesting that sBzKs can have a wide range of SFEs. Comparisons of far-infrared luminosity, gas mass, and stellar mass among the sBzKs suggest that SDF-26821 is at an earlier stage of forming stars with a similar SFE and/or more efficiently forming stars than the two $z$$\sim$ 1.5 sBzKs. The higher SFEs and specific star-formation rates of the sBzKs compared to local spirals are indicative of a difference in the star-formation modes between these systems, suggesting that sBzKs are not just scaled-up versions of local spirals.
New Period Investigation of Algol-like Near-Contact Binary EG Cephei
Authors: Ying Zhu Li , Sheng Bang Qian , Wen Ping Liao , Miloslav Zejda , Zdenek Mikulášek 
Published: March 2014

Abstract
The Algol-like Near Contact Binary EG Cephei was observed in 2008 October. One new observed time of the secondary minimum was derived in $BV(IR)_{\rm c}$ bands. It turns out that the times of minima at longer wavelengths occur earlier than the shorter ones. All of the available eclipse times, including 735 epochs, spanning more than 100 years were analyzed. A period oscillation with a period of 35.8($\pm$0.1)yr and an amplitude of about 0.0037($\pm$0.0002)d was found, while undergoing a secular increase at a rate of $dP/dt$$=$ 3.4 $\times$ 10$^{-8}$($\pm$0.1)dyr$^{-1}$. This continuous period increase may be caused by mass transfer from the secondary component to the primary one on a thermal timescale, which is consistent with the Algol-like semi-detached configuration of EG Cep. Combining with the spectroscopic and photometric results, we derived a conservative mass-transfer rate of this target, $dM/dt$$=$ 3.0($\pm$0.1) $\times$ 10$^{-8}M_{\odot}$yr$^{-1}$. The oscillation part of the period variation may be the result of a light-time effect due to the existence of a coplanar additional body with a mass of $M_{3}$$=$ 0.11$M_{\odot}$, and a corresponding radius of $a_{3}$$=$ 14AU. The presumed third body may play an important role in the evolution of this system.
Observational Appearance of Black Hole Winds
Authors: Fukue Jun , Sumitomo Naoko 
Published: March 2014

Abstract
We examine the observational appearance of an optically thick, spherically symmetric, relativistic wind (a black hole wind). In a relativistic flow, the apparent optical depth becomes small in the downstream direction, while it is large in the upstream direction due to the relativistic effect. Hence, the apparent photosphere of the relativistic flow depends on the flow velocity and direction as well as the density distribution. We calculated the temperature distribution of the apparent photosphere of the optically thick black hole wind, where the wind speed was assumed to be constant and radiation dominates matter, for various values of the wind speed and mass-outflow rate. We found that the limb-darkening effect is strongly enhanced in the relativistic regime. We also found that the observed luminosities of the black hole wind become large as the wind speed increases, but do not depend on the mass-outflow rate.
Subaru/COMICS Mid-Infrared Observation of the Near-Nucleus Region of Comet 17P/Holmes at the Early Phase of an Outburst
Authors: Watanabe Jun-ichi , Honda Mitsuhiko , Ishiguro Masateru , Ootsubo Takafumi , Sarugaku Yuki , Kadono Toshihiko , Sakon Itsuki , Fuse Tetsuharu , Takato Naruhisa , Furusho Reiko 
Published: March 2014

Abstract
Mid-infrared 8–25$\mu$m imaging and spectroscopic observations of the comet 17P/Holmes in the early phase of its outburst in brightness were performed on 2007 October 25–28UT using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2-m Subaru Telescope. We detected an isolated dust cloud that moved toward the south-west direction from the nucleus. The 11.2$\mu$m peak of a crystalline silicate feature onto a broad amorphous silicate feature was also detected both in the central condensation of the nucleus and an isolated dust cloud. The color temperature of the isolated dust cloud was estimated to be $\sim$200 K, which is slightly higher than the black-body temperature. Our analysis of the motion indicates that the isolated cloud moved anti-sunward. We propose several possibilities for the motion of the cloud: fluffy dust particles in the isolated cloud started to depart from the nucleus due to radiation pressure almost as soon as the main outburst occurred, or dust particles moved by some other anti-sunward forces, such as a rocket effect and photophoresis when the surrounding dust coma became optically thin. The origin and the nature of the isolated dust cloud are discussed in this paper.
A Super Bubble Candidate in the Galactic Center and a Local Enhancement G359.77$-$0.09
Authors: Mori Hideyuki , Hyodo Yoshiaki , Tsuru Takeshi Go , Nobukawa Masayoshi , Koyama Katsuji 
Published: March 2014

Abstract
A 20$^\prime$$\times$ 16$^\prime;$ elliptical ring-like structure has been found near the Galactic center in the narrow energy band corresponding to the K$\alpha$ line from He-like sulfur. In the ring, two diffuse sources are found, a supernova remnant candidate, G359.79$-$0.26, and an unidentified source, G359.77$-$0.09. The X-ray spectrum of G359.77$-$0.09 is similar to that of G359.79$-$0.26, which can be explained by an absorbed thin thermal plasma model with temperatures of 0.7 and 1.0 keV. The absorption column densities of these two sources are large ($N_{\rm H}$$=$ 6.9 $\times$ 10$^{22}$ and 4.5 $\times$ 10$^{22}$cm$^{-2}$) and are consistent with that of the Galactic center distance. The X-ray spectrum extracted from the ring-like structure is also represented by an absorbed thin thermal plasma model ($kT_{\rm e}$$\sim$ 0.9 keV). The thermal energy of the plasma filling the ring-like structure is estimated to be 1.0 $\times$ 10$^{51}$erg. We therefore propose that the two sources comprise a single ring-like object, which is possibly a super bubble with a size of 49 pc $\times$40 pc in the Galactic center region.
Period Changes of DF Hydrae: Evidence of Mass Transfer and the Presence of a Cool Tertiary Companion
Authors: Xiang Fuyuan , Xie Wenli , Tian Yongpo , Tao Xia 
Published: March 2014

Abstract
Combining our six new determined times of light minimum obtained from 2001 to 2007 with others compiled from the literature, we investigated the period changes of DF Hydrae. The general trend of the $O-C$ curve based on all available data reveals that the period of the binary star is increasing continuously at a rate of $dP/dt$$=$$+$1.11($\pm$0.02) $\times$ 10$^{-7}$dyr$^{-1}$. After the long-term period increase was removed from the $O-C$ diagram, it was discovered that the residuals of the CCD and photoelectric observations suggest a small-amplitude cyclic oscillation with a period of 21.5 years. The continuous period increase can be explained by mass transfer from the secondary to the primary, indicating that DF Hydrae is on the TRO-controlled stage of the evolutionary scenario proposed by Qian. The cyclic period variation suggests that DF Hydrae is a triple system containing a cool tertiary component with a mass of $M_3$sin${i^{\prime}}$$=$ 0.21$M_{\odot}$ in a 21.5-year orbit. By removing angular momentum from the central binary system via Kozai oscillation or a combination of the Kozai cycle and tidal friction, the tertiary companion may play an important role for the formation and evolution of the contact system, which makes the eclipsing pair to have a short initial orbital period (i.e., $P$$\lt$ 5$^{\rm d}$). In that case, the detached progenitor of DF Hydrae evolves into the present contact configuration via a combination of magnetic braking and a case A mass transfer.
Calibration and Performance of the AKARI Far-Infrared Surveyor (FIS) — Slow-Scan Observation Mode for Point-Sources
Authors: Shirahata Mai , Matsuura Shuji , Hasegawa Sunao , Ootsubo Takafumi , Makiuti Sin’itirou , Yamamura Issei , Nakagawa Takao , Kawada Mitsunobu , Kaneda Hidehiro , Shibai Hiroshi , Doi Yasuo , Suzuki Toyoaki , Müller Thomas , Cohen Martin 
Published: March 2014

Abstract
We present the characterization and calibration of the Slow-Scan observation mode of the Far-Infrared Surveyor (FIS) onboard the AKARI satellite. The FIS, one of the two focal-plane instruments on AKARI, has four photometric bands between 50–180$\mu$m with two types of Ge:Ga array detectors. In addition to the All-Sky Survey, FIS has also taken detailed far-infrared images of selected targets by using the Slow-Scan mode. The sensitivity of the Slow-Scan mode is one to two orders of magnitude better than that of the All-Sky Survey, because the exposure time on a targeted source is much longer. The point spread functions (PSFs) were obtained by observing several bright point-like objects, such as asteroids, stars, and galaxies. The derived full widths at the half maximum (FWHMs) are $\sim$30$^{\prime\prime}$ for the two shorter wavelength bands and $\sim$40$^{\prime\prime}$ for the two longer wavelength bands, being consistent with those expected by optical simulation, although a certain amount of excess is seen in the tails of the PSFs. A flux calibration was performed by observations of well-established photometric calibration standards (asteroids and stars) over a wide range of fluxes. After establishing the method of aperture photometry, the photometric accuracy for point-sources is better than $\pm$15% in all of the bands, expect for the longest wavelength.