bluuebunny/crossref_metadata_2025_split huggingface dataset:
Verification of the Effectiveness of VSOP-2 Phase Referencing with a Newly Developed Simulation Tool, ARIS
Authors: Asaki Yoshiharu , Sudou Hiroshi , Kono Yusuke , Doi Akihiro , Dodson Richard , Pradel Nicolas , Murata Yasuhiro , Mochizuki Nanako , Edwards Philip G. , Sasao Tetsuo , Fomalont Edward B. 
Published: March 2014

Abstract
The next-generation space VLBI mission, VSOP-2, is expected to provide unprecedented spatial resolution at 8.4, 22, and 43 GHz. In this report, phase referencing with VSOP-2 is examined in detail based on a simulation tool called ARIS. The criterion for successful phase referencing was set to keep the phase errors below one radian. Simulations with ARIS reveal that phase referencing achieves good performance at 8.4 GHz, even under poor tropospheric conditions. At 22 and 43 GHz, it is recommended to conduct phase referencing observations under good or typical tropospheric conditions. The satellite is required to have an attitude-switching capability with a one-minute or shorter cycle, and an orbit determination accuracy higher than $\sim$10 cm at apogee; the phase referencing calibrators are required to have a signal-to-noise ratio larger than four for a single scan. The probability to find a suitable phase referencing calibrator was estimated by using VLBI surveys. From the viewpoint of calibrator availability, VSOP-2 phase referencing at 8.4 GHz is promising. However, the chance of finding suitable calibrators at 22 and 43 GHz is significantly reduced; it is important to conduct specific investigations for each target at those frequencies.
Observational Characteristics of the First Protostellar Cores
Authors: Omukai Kazuyuki 
Published: March 2014

Abstract
First protostellar cores are young stellar objects in the earliest evolutionary stage. They are hydrostatic objects formed soon after the central portions of star-forming cores become optically thick to dust emission. We consider their characteristics in the emitted radiation, and discuss their evolution with increasing mass of the cores. Particular attention is paid to detailed radiative and chemical processes in the postshock relaxation layer located at the surface of the core, where the majority of radiation is emitted. Most of the radiation is originally emitted in the dust continuum in mid-infrared wavelength ($\sim$ 10–30 $\mu$m), which reprocessed to far-infrared with $\sim$ 100–200 $\mu$m. Although some fraction ($\sim$ 0.1) of the radiation energy is emitted in the H$_2$O lines at the accretion shock, most is absorbed and reemitted in the dust continuum in the envelope. The H$_2$O lines account for at most $\sim 1/100$ of the observed luminosity. If a cavity is present in the envelope due to outflow or rotation, the dust and H$_2$O line emission in the mid-infrared wavelength from the shock can be observed directly, or as a reflection nebula. Among forthcoming observational facillities, SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is the most suitable for detecting either direct or processed radiation from first-core objects.
Lyman Break Galaxies at z$\sim$5: Rest-Frame UV Spectra. II
Authors: Ando Masataka , Ohta Kouji , Iwata Ikuru , Akiyama Masayuki , Aoki Kentaro , Tamura Naoyuki 
Published: March 2014

Abstract
We present spectroscopy results of Lyman break galaxies (LBGs) at z$\sim$5 in the J0053$+$1234 field. Among five bright candidates with z$'$$\;&lt;\;$25.0 mag, two objects are confirmed to be at z$\;\sim\;$5. The equivalent widths (EWs) of Ly$\alpha$ emission of the 2 LBGs are not so strong as to be detected as Ly$\alpha$ emitters, and one of them shows strong low-ionization interstellar (LIS) metal absorption lines. Two faint objects with z$'$$\geq$25.0 mag are also confirmed to be at z$\;\sim\;$5, and their spectra show strong Ly$\alpha$ emission in contrast to bright ones. These results suggest a deficiency of strong Ly$\alpha$ emission in bright LBGs at z$\;\sim\;$5, as discussed in our previous paper. Combined with our previous spectra of LBGs at z$\;\sim\;$5, obtained around the Hubble Deep Field-North (HDF-N), we made a composite spectrum of luminous ($M_{1400} \leq -$21.5 mag) LBGs at z$\;\sim\;$5. The resultant spectrum shows weak Ly$\alpha$ emission and strong LIS absorptions, which suggest that the bright LBGs at z$\;\sim\;$5 have chemically evolved at least to $\sim$0.1 solar metallicity. For a part of our sample in the HDF-N region, we obtained near-to-mid infrared data, which constrain the stellar masses of these objects. With the stellar mass and the metallicity estimated from the LIS absorptions, the metallicities of the LBGs at z$\;\sim\;$5 tend to be lower than those of galaxies with the same stellar mass at z$\lesssim 2$, although the uncertainty is very large.
The Impact of Type Ia Supernova Explosions on the Companion in a Binary System
Authors: Meng Xiangcun , Chen Xuefei , Han Zhanwen 
Published: March 2014

Abstract
Using a simple analytic method, we can calculate the impact effect between the ejecta of a SN Ia and its companion to survey the influence of the initial parameters of the progenitor’s system, which is useful for searching the companion in an explosion remnant. The companion models are obtained from Eggleton’s evolution code. The results are divided into two groups based on the mass-transfer stage. For a given condition, more hydrogen-rich material is stripped from the envelope of a Hertzsprung-gap companion than that of a main-sequence companion, while a larger kick velocity and a larger luminosity are gained for a main-sequence companion. The kick velocity is too low to significantly affect the final spatial velocity of the companion, which is mainly affected by the initial parameters of the progenitor systems. The spatial velocity of the stripped material has an upper limit within the range of 8000–9500 km s$^{-1}$, which only depends on the total kinetic energy of the explosion. The stripped mass, the ratio of the stripped mass to the companion mass and the kick velocity of the companion all significantly depend on the initial companion mass and the orbital period. Our model may naturally explain the spatial velocity of the star G in the remnant of Tycho’s supernova, while an energy-loss mechanism is needed to interpret its luminosity.
Observation of C$_8$H$^-$ toward IRC +10216
Authors: Kentarou Kawaguchi , Fujimori Ryuji , Aimi Sayaka , Takano Shuro , Okabayashi Emi Y. , Gupta Harshal , BrÜnken Sandra , Gottlieb Carl A. , McCarthy Michael C. , Thaddeus Patrick 
Published: March 2014

Abstract
Five rotational lines of the C$_8$H$^-$ ion were observed in the circumstellar envelope of IRC $+$10216 with the Nobeyama 45 m telescope. An improved value of the column density of the C$_8$H radical yielded a [C$_8$H$^-$]$/$[C$_8$H] ratio of 37%—nearly 4 times larger than the [C$_6$H$^-$]$/$[C$_6$H] ratio (8.6%) and nearly 1500 times the [C$_4$H$^-$]$/$[C$_4$H] ratio (0.024%), which may indicate more efficient formation of longer carbon chain anions. The excitation temperature of C$_8$H$^-$ (16$\;\pm\;$2 K) derived here is somewhat lower than that of the two smaller anions C$_6$H$^-$ (32 K) and C$_4$H$^-$ (23 K) in IRC $+$10216.
Discoveries of Diffuse Iron Line Sources from the Sgr B Region
Authors: Koyama Katsuji , Inui Tatsuya , Hyodo Yoshiaki , Matsumoto Hironori , Tsuru Takeshi Go , Maeda Yoshitomo , Murakami Hiroshi , Yamauchi Shigeo , Kissel Steven E. , Chan Kai-Wing , Soong Yang 
Published: March 2014

Abstract
The radio complex Sgr B region was observed with the X-ray Imaging Spectrometer (XIS) on board Suzaku. This region exhibits diffuse iron lines at 6.4, 6.7, and 6.9 keV, which are $\mathrm{K}\alpha$ lines of Fe I (neutral iron), Fe XXV (He-like iron), and Fe XXVI (H-like iron), respectively. The high energy resolving power of the XIS provided separate maps of the K-shell transition lines from Fe I (6.4 keV) and Fe XXV (6.7 keV). Although the 6.7 keV line is smoothly distributed over the Sgr B region, a local excess is found near $(l, b) = ({0\rlap {.}{}^{\mathrm {\circ }}61}, {0\rlap {.}{}^{\mathrm {\circ }}01})$, possibly due to a new SNR. The plasma temperature is $kT\sim 3 \,\mathrm{keV}$ and the age is estimated to be younger than $7 \times 10^{3} \,\mathrm{yr}$. The 6.4 keV image is clumpy with local excesses near Sgr B2 and at $(l, b) = ({0\rlap {.}{}^{\mathrm {\circ }}74},- {0\rlap {.}{}^{\mathrm {\circ }}09})$. Like Sgr B2, this excess may be another candidate of an X-ray reflection nebula.
X-Ray Spectrum of Sagittarius A East
Authors: Koyama Katsuji , Uchiyama Hideki , Hyodo Yoshiaki , Matsumoto Hironori , Tsuru Takeshi Go , Ozaki Masanobu , Maeda Yoshitomo , Murakami Hiroshi 
Published: March 2014

Abstract
Sgr A East is a young SNR located in the Galactic Center (GC) region. Since the GC region is occupied by diffuse X-ray emission (GCDX) with a strong 6.7 keV line, an estimation of the GCDX is crucial to study the X-ray spectrum of Sgr A East. The flux and spectrum of the GCDX are found to be smoothly distributed around and across Sgr A East, and hence a reliable GCDX subtraction can be made. This paper presents the X-ray spectrum of Sgr A East with the XIS on board Suzaku. In addition to the previously reported $\mathrm{K}\alpha$ lines from S XV, Ar XVII, Ca XIX, and Fe XXV (all He-like atoms), we found $\mathrm{K}\alpha$ lines from S XVI, Ar XVIII, Fe XXVI (all hydrogenic atoms), and Ni XXVII (He-like), $\mathrm{K}\beta$ lines from S XV, Ar XVII, and Fe XXV, and a $\mathrm{K}\gamma$ line from Fe XXV. Plasma diagnostics using these lines revealed the presence of at least a two-temperature plasma. The overall spectrum can be fitted with a two-temperature ($\sim 1.2 \,\mathrm{keV}$ and $\sim 6 \,\mathrm{keV}$) plasma in ionization equilibrium plus a power-law component.
Suzaku Observation of Two Ultraluminous X-Ray Sources in NGC 1313
Authors: Mizuno Tsunefumi , Miyawaki Ryohei , Ebisawa Ken , Kubota Aya , Miyamoto Masao , Winter Lisa M. , Ueda Yoshihiro , Isobe Naoki , Dewangan Gulab C. , Done Chris , Griffiths Richard E. , Haba Yoshito , Kokubun Motohide , Kotoku Jun’ichi , Makishima Kazuo , Matsushita Kyoko , Mushotzky Ricard F. , Namiki Masaaki , Petre Robert , Takahashi Hiromitsu , Tamagawa Toru , Terashima Yuichi 
Published: March 2014

Abstract
Two ultraluminous X-ray sources (ULXs) in the nearby Sb galaxy NGC 1313, named X-1 and X-2, were observed with Suzaku on 2005 September 15. During the observation for a net exposure of 28 ks (but over a gross time span of 90 ks), both objects varied in intensity by about 50%. The 0.4–10 keV X-ray luminosities of X-1 and X-2 were measured as $2.5 \times 10^{40} \,\mathrm{erg} \,\mathrm{s}^{-1}$ and $5.8 \times 10^{39} \,\mathrm{erg} \,\mathrm{s}^{-1}$, respectively, with the former exhibiting the highest ever reported for this ULX. The spectrum of X-1 can be explained by the sum of a strong and variable power-law component with a high-energy cutoff, and a stable multicolor blackbody with an innermost disk temperature of $\sim 0.2 \,\mathrm{keV}$. These results suggest that X-1 was in a “very high” state, where disk emission is strongly Comptonized. The absorber within NGC 1313 toward X-1 is suggested to have a subsolar oxygen abundance. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor blackbody model with an innermost disk temperature of 1.2–1.3 keV, and becomes flatter as the source becomes brighter. Hence, X-2 is interpreted to be in a slim-disk state. These results suggest that the two ULXs have black hole masses of some dozens to a few hundred of solar masses.
Observations of Sunspot Oscillations in G Band and Ca II H Line with Solar Optical Telescope on Hinode
Authors: Nagashima Kaori , Sekii Takashi , Kosovichev Alexander G. , Shibahashi Hiromoto , Tsuneta Saku , Ichimoto Kiyoshi , Katsukawa Yukio , Lites Bruce , Nagata Shin’ichi , Shimizu Toshifumi , Shine Richard A. , Suematsu Yoshinori , Tarbell Theodore D. , Title Alan M. 
Published: March 2014

Abstract
Exploiting high-resolution observations made by the Solar Optical Telescope on board Hinode, we investigate the spatial distribution of the power spectral density of the oscillatory signal in and around the active region NOAA 10935. The G-band data show that in the umbra the oscillatory power is suppressed in all frequency ranges. On the other hand, in Ca II H intensity maps oscillations in the umbra, so-called umbral flashes, are clearly seen with the power peaking around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with the spatial scale of the umbral flashes over most of the umbra, but there is a region with suppressed power at the center of the umbra. The origin and property of this node-like feature remain unexplained.
Response of the Solar Atmosphere to Magnetic Flux Emergence from Hinode Observations
Authors: Li Hui , Sakurai Takashi , Ichimito Kiyoshi , Suematsu Yoshinori , Tsuneta Saku , Katsukawa Yukio , Shimizu Toshifumi , Shine Richard A. , Tarbell Theodore D. , Title Alan M. , Lites Bruce , Kubo Masahito , Nagata Shin’ichi , Kotoku Jun , Shibasaki Kiyoto , Saar Steven H. , Bobra Monica 
Published: March 2014

Abstract
In the present work, we used optical and X-ray data from the Hinode satellite to study the response of the solar chromosphere and the corona to the emerging flux in the photosphere. In total, twelve emerging flux regions (EFRs) were selected to conduct this study. The average separation of the two polarities and the lifetime of these EFRs were 3$\rlap {.} {}^{\prime\prime}$2 and 40 min, respectively. All of these regions showed corresponding enhanced emission in the Ca II H line and soft X-rays with different filters, indicating that these small-scale and short-lived EFRs heat the chromosphere and the corona to some extent.
A Measurement of Proper Motions of SiO Maser Sources in the Galactic Center with the VLBA
Authors: Oyama Tomoaki , Miyoshi Makoto , Deguchi Shuji , Imai Hiroshi , Shen Zhi-Qiang 
Published: March 2014

Abstract
We report on the high-precision astrometric observations of maser sources around the Galactic Center in the SiO $J=1$-0 $v=1$ and 2 lines with the VLBA during 2001–2004. With phase-referencing interferometry referred to the radio continuum source Sgr A*, accurate positions of masers were obtained for three detected objects: IRS 10EE (7 epochs), IRS 15NE (2 epochs), and SiO 6(only 1 epoch). Because circumstellar masers of these objects were resolved into several components, proper motions for the maser sources were derived with several different methods. Combining our VLBA results with those of the previous VLA observations, we obtained the IRS 10EE proper motion of 76$\pm$3kms$^{-1}$ (at 8kpc) to the south relative to Sgr A*. Almost null proper motion of this star in the east–west direction results in a net transverse motion of the infrared reference frame of about 30$\pm$9kms$^{-1}$ to the west relative to Sgr A*. The proper-motion data also suggests that IRS 10EE is an astrometric binary with an unseen massive companion.
Aperture Synthesis Imaging of a High-Velocity Compact Cloud near the Galactic Center
Authors: Oka Tomoharu , Hasegawa Tetsuo , White Glenn J. , Sato Fumio , Tsuboi Masato , Miyazaki Atsushi 
Published: March 2014

Abstract
We observed CO $J =$ 1-0 and HCN $J =$ 1-0 line emission toward a high-velocity, compact molecular cloud, CO0.02-0.02, near the center of our Galaxy, using the Nobeyama Millimeter Array (NMA). A CO velocity-integrated map with a resolution of 4.3”$\times$2.4” shows two oval clumps with sizes of 0.8pc. These clumps are seperated by 1.2pc, being located at the eastern and southwestern peripheries of the CO0.02-0.02 cloud. The overall distribution of HCN emission coincides with that taken with the Nobeyama 45m telescope. The HCN velocity-integrated map with a resolution of 6.1”$\times$3.4” shows two prominent peaks in the cloud center. Both NMA maps at $V_{\rm LSR}$$\sim$110kms$^{-1}$ show an arc-shaped edge in the southeast, which may correspond to the edge of the “emission cavity” found in the CO $J =$ 3-2 integrated-intesity map. We also noticed a faint radio continuum “arc” that encircles the bulk of the CO0.02-0.02 cloud. These results support the notion that CO0.02-0.02 has been accelerated, heated, and compressed in a series of supernova shocks that occurred within the last (3-5)$\times$10$^{4}$yr. We suggest that a massive compact cluster with an age of 10-30Myr is responsible for the formation of the CO0.02-0.02 cloud.
Cooperative Observation of Ellerman Bombs between the Solar Optical Telescope aboard Hinode and Hida/Domeless Solar Telescope
Authors: Matsumoto Takuma , Kitai Reizaburo , Shibata Kazunari , Nagata Shin’ichi , Otsuji Kenichi , Nakamura Tahei , Watanabe Hiroko , Tsuneta Saku , Suematsu Yoshinori , Ichimoto Kiyoshi , Shimizu Toshifumi , Katsukawa Yukio , Tarbell Theodore D. , Lites Bruce W. , Shine Richard A. , Title Alan M. 
Published: March 2014

Abstract
High-resolution CaIIH broad-band filter images of NOAA10933 on 2007 January 5 were obtained by the Solar Optical Telescope aboard the Hinode satellite. Many small-scale ($\sim$1") bright points were observed outside the sunspot and inside the emerging flux region. We identified some of these bright points with Ellerman bombs (EBs) by using H$\alpha$ images taken by the Domeless Solar Telescope at Hida observatory. The sub-arcsec structures of two EBs seen in CaIIH were studied in detail. Our observation showed the following two aspects: (1) The CaIIH bright points identified with EBs were associated with the bipolar magnetic field structures, as reported by previous studies. (2) The structure of the CaIIH bright points turned out to consist of the following two parts: a central elongated bright core (0.7" $\times$ 0.5") located along the magnetic neutral line and a diffuse halo (1.2" $\times$ 1.8").
Subaru/MOIRCS Near-Infrared Imaging in the Proto-Cluster Region at z = 3.1
Authors: Uchimoto Yuka Katsuno , Suzuki Ryuji , Tokoku Chihiro , Ichikawa Takashi , Konishi Masahiro , Yoshikawa Tomohiro , Omata Koji , Nishimura Tetsuo , Yamada Toru , Tanaka Ichi , Kajisawa Masaru , Akiyama Masayuki , Matsuda Yuichi , Yamauchi Ryosuke , Hayashino Tomoki 
Published: March 2014

Abstract
We present the results of deep near-infrared imaging observations of the $z=3.1$ proto-cluster region in the SSA 22a field taken by MOIRCS mounted on the Subaru Telescope. We observed a 21.7 arcmin$^2$ field to depths of $J=$ 24.5, $H=$ 24.3, and $K=$ 23.9 (5$\sigma$). We examined the distribution of the $K$-selected galaxies at $z \sim 3$ by using a simple color cut for distant red galaxies (DRGs) as well as a photometric-redshift selection technique. The marginal density excess of DRGs and the photo-$z$ selected objects were found around the two most luminous Ly$\alpha$ blobs (LABs). We investigated the correlation between the $K$-selected objects and the LABs, and found that several galaxies with stellar mass, $M_* = 10^{9}$–$10^{11} M_\odot$, exist in the vicinity of LABs, especially around the two most luminous ones. We also found that 7 of the 8LABs in the field have plausible $K_{\rm s}$-band counterparts, and the sum of the stellar mass possibly associated with LABs correlates with their luminosity and surface brightness, which implies that the origin of Ly$\alpha$ emission may be closely correlated with their previous star-formation phenomena.
Modeling Nonlinear Evolution of Baryon Acoustic Oscillations: Convergence Regime of $N$-body Simulations and Analytic Models
Authors: Nishimichi Takahiro , Shirata Akihito , Taruya Atsushi , Yahata Kazuhiro , Saito Shun , Suto Yasushi , Takahashi Ryuichi , Yoshida Naoki , Matsubara Takahiko , Sugiyama Naoshi , Kayo Issha , Jing Yipeng , Yoshikawa Kohji 
Published: March 2014

Abstract
We used a series of cosmological $N$-body simulations and various analytic models to study the evolution of the matter power spectrum in real space in a $\Lambda$ cold dark matter universe. We compared the results of $N$-body simulations against three analytical model predictions; standard perturbation theory, renormalized perturbation theory, and a closure approximation. We included the effects from a finite simulation box size under comparison. We determined the values of the maximum wavenumbers, $k^{\rm lim}_{1\%}$ and $k^{\rm lim}_{3\%}$, below which the analytic models and the simulation results agree with accuracy to within 1 and 3 percent. We then provided a simple empirical function that describes the convergence regime determined by comparisons between our simulations and the analytical models. We found that if we use the Fourier modes within the convergence regime alone, the characteristic scale of baryon acoustic oscillations can be determined with an accuracy of 1% from future surveys with a volume of a few $h^{-3}$Gpc$^3$ at z$\sim$ 1 or z$\sim$ 3 in the absence of any systematic distortion of the power spectrum.
North Ecliptic Pole Wide Field Survey of AKARI: Survey Strategy and Data Characteristics
Authors: Lee Hyung Mok , Kim Seong Jin , Im Myungshin , Matsuhara Hideo , Oyabu Shinki , Wada Takehiko , Nakagawa Takao , Ko Jongwan , Shim Hyun Jin , Lee Myung Gyoon , Hwang Narae , Takagi Toshinobu , Pearson Chris 
Published: March 2014

Abstract
We present the survey strategy and the data characteristics of the North Ecliptic Pole (NEP) Wide Survey of AKARI. The survey was carried out for about one year starting from 2006 May with 9 passbands from 2.5 to 24 $\mu$m and the areal coverage of about 5.8 degree$^2$ centered on NEP. The survey depth reaches to 21.8 AB magnitude near infrared (NIR) bands, and $\sim$18.6 AB magnitude at the mid infrared (MIR) bands such as 15 and 18 $\mu$m. The total number of sources detected in this survey is about 104000, with more sources in NIR than in the MIR. We have cross matched infrared sources with optically identified sources in CFHT imaging survey which covered about 2 degree$^2$ within NEP-Wide survey region in order to characterize the nature of infrared sources. The majority of the MIR sources at 15 and 18 $\mu$m bands are found to be star forming disk galaxies, with smaller fraction of early type galaxies and AGNs. We found that a large fraction (60%–80%) of bright sources in 9 and 11 $\mu$m is stars while stellar fraction decreases toward fainter sources. We present the histograms of the sources at MIR bands at 9, 11, 15, and 18 $\mu$m. The number of sources per magnitude thus varies as $m^{0.6}$ for longer wavelength sources while shorter wavelength sources show steeper variation with $m$, where $m$ is the AB magnitude.
Global Radiation-Magnetohydrodynamic Simulations of Black-Hole Accretion Flow and Outflow: Unified Model of Three States
Authors: Ohsuga Ken , Mineshige Shin , Mori Masao , Kato Yoshiaki 
Published: March 2014

Abstract
Black-hole accretion systems are known to possess several distinct modes (or spectral states), such as low/hard state and high/soft state. Since the dynamics of the corresponding flows is distinct, theoretical models were separately considered for each state. We here propose a unified model based on our new, global, two-dimensional radiation-magnetohydrodynamic simulations. By controlling a density normalization we could for the first time reproduce three distinct modes of accretion flow and outflow with one numerical code. When the density is large (model A), a geometrically thick, very luminous disk forms, in which photon trapping takes place. When the density is moderate (model B), the accreting gas can effectively be cooled by emitting radiation, thus generating a thin disk, i.e., a soft-state disk. When the density is too low for radiative cooling to be important (model C), a disk becomes hot, thick, and faint; i.e., a hard-state disk. The magnetic energy is amplified within the disk up to about twice, 30%, and 20% of the gas energy in models A, B, and C, respectively. Notably, the disk outflows with helical magnetic fields, which are driven either by radiation-pressure force or magnetic-pressure force, are ubiquitous in any accretion modes. Finally, our simulations are consistent with the phenomenological $\alpha$-viscosity prescription; that is, the disk viscosity is proportional to the pressure.