bluuebunny/crossref_metadata_2025_split huggingface dataset:
Number Density of Bright Lyman-Break Galaxies at z ∼ 6 in the Subaru Deep Field
Authors: Shimasaku Kazuhiro , Ouchi Masami , Furusawa Hisanori , Yoshida Makiko , Kashikawa Nobunari , Okamura Sadanori 
Published: March 2014

Abstract
We report on bright Lyman-break galaxies (LBGs) selected in a $767 \,\mathrm{arcmin}^2$ area of the Subaru Deep Field. The selection was made in the $i-z_{\mathrm{R}}$ versus $z_{\mathrm{B}}-z_{\mathrm{R}}$ plane, where $z_{\mathrm{B}}$ and $z_{\mathrm{R}}$ are new bandpasses with a central wavelength of 8842 Å and 9841 Å, respectively. We detected 12 LBG candidates down to $z_{\mathrm{R}} = 25.4$, and calculated the normalization of the rest-frame far-ultraviolet (FUV: $\simeq 1400 \,{Å}$) luminosity function at $M_{\mathrm{FUV}} =-21.6$ to be $\phi(-21.6) = (2.6 \pm 0.7) \times 10^{-5} \,\mathrm{mag}^{-1} \,\mathrm{Mpc}^{-3}$. This must be the most reliable measurement ever obtained of the number density of bright $z\sim 6$ LBGs, because it is more robust against both contamination and cosmic variance than previous values. The FUV luminosity density contributed from LBGs brighter than $M_{\mathrm{FUV}} =-21.3$ is $(2.8 \pm 0.8) \times 10^{24} \,\mathrm{erg} \,\mathrm{s}^{-1} \,\mathrm{Hz}^{-1} \,\mathrm{Mpc}^{-3}$, which is equivalent to a star-formation rate density of $(3.5 \pm 1.0) \times 10^{-4} \,{{{M}_{\odot}}} \,\mathrm{yr}^{-1} \,\mathrm{Mpc}^{-3}$. We find that the FUV luminosity density of bright galaxies increases by an order of magnitude from $z\sim 6$ to $\sim 3$, and then drops by $10^3$ from $z \sim 3$ to the present epoch. The evolutionary behavior of bright LBGs resembles that of luminous dusty star-forming galaxies and bright QSOs. The redshift of $z \sim 3$ appears to be a remarkable era in the cosmic history when massive galaxies were being intensively formed.
X-Ray Emission from a Supernova Remnant, G344.7−0.1, Observed in the ASCA Galactic Plane Survey
Authors: Yamauchi Shigeo , Ueno Masaru , Koyama Katsuji , Bamba Aya 
Published: March 2014

Abstract
X-ray emission from a cataloged radio supernova remnant (SNR), G344.7$-$0.1, was observed in the ASCA Galactic Plane Survey. The X-ray image showed extended emission with a diameter of $6' \hbox{--} 8'$. The X-ray spectrum exhibited emission lines from He-like Si, S, Ar, and Ca, which indicates that the X-rays have a thermal plasma origin. The spectrum was represented by a thin thermal plasma model with a temperature of 0.7–0.8 keV. The model fit showed that S and Ca are overabundant relative to the solar values. In addition to the emission lines from highly ionized atoms, an emission line at an energy of $\sim 6.4 \,\mathrm{keV}$ was found. This line is attributable to a K transition line from low-ionized iron. The strong Fe-K$\alpha$ line may suggest the existence of an Fe-rich plasma.
Millimeter Continuum Observations of McNeil’s Nebula Object
Authors: Tsukagoshi Takashi , Kitamura Yoshimi , Kawabe Ryohei , Saito Masao , Yokogawa Sozo , Kurono Yasutaka 
Published: March 2014

Abstract
We performed 98 and 110 GHz continuum monitoring observations of the FU Orionis candidate, McNeil’s Nebula Object (MNO), from 2004 February to May, with the Nobeyama Millimeter Array. In this study, we succeeded in detecting compact ($\sim 3000 \,\mathrm{AU}$) dust emission towards the position of LMZ 12, the millimeter counterpart of MNO. From monitoring observations, however, we could not find any distinct time variation of the total flux densities for the period from 2004 February to May. The Spectral Energy Distribution (SED) of MNO in $\lambda = 0.45 \hbox{--} 3 \,\mathrm{mm}$, which shows no increase in brightness after the outburst, is found to have a power-law form with an index of 2.5; the index corresponds to a $\mathrm{\beta}$ index of 0.5 for the dust mass opacity coefficient. If we consider the continuum emission from MNO as an optically thin thermal one from the dust in the envelope or the outer cold region of the accretion disk around MNO, the total flux densities of the emission give a mass of the circumstellar material of $0.04 \pm 0.01 \,{{{M}_{\odot}}}$, which is slightly larger than the disk mass of T Tauri stars ($\sim 0.01 \,{{{M}_{\odot}}}$). It is very likely, based on these results, that MNO experiences an FU Orionis outburst in the transient stage from a protostar to a T Tauri star. Furthermore, considering the non-detection of an millimeter outburst together with the outburst at optical and IR wavelengths, we suggest that the eruptive phenomenon occurs in the innermost hot region of the disk.
Discovery of a Fifth Image of the Large Separation Gravitationally Lensed Quasar SDSS J1004+4112
Authors: Naohisa Inada , Oguri Masamune , Keeton Charles R. , Eisenstein Daniel J. , Castander Francisco J. , Chiu Kuenley , Hall Patrick B. , Hennawi Joseph F. , Johnston David E. , Pindor Bartosz , Richards Gordon T. , Rix Hans-Walter , Schneider Donald P. , Zheng Wei 
Published: March 2014

Abstract
We report on the discovery of a fifth lensed image in the large separation lensed quasar system SDSS J1004$+$4112. A faint point source located ${0\rlap {.}{}^{\mathrm {\prime \prime }}2}$ from the center of the brightest galaxy in the lensing cluster was detected in images taken with the Advanced Camera for Surveys (ACS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope. The flux ratio between the point source and the brightest lensed component in the ACS image is similar to that in the NICMOS image. The location and brightness of the point source are consistent with lens model predictions for a lensed image. We therefore conclude that the point source is likely to be a fifth lensed image of the source quasar. In addition, the NICMOS image reveals the lensed host galaxy of the source quasar, which can strongly constrain the structure of the lensing critical curves, and thereby the mass distribution of the lensing cluster.
Water-Vapor Maser Survey for Active Galactic Nuclei: A Megamaser in NGC 6926
Authors: Sato Naoko , Yamauchi Aya , Ishihara Yuko , Sorai Kazuo , Kuno Nario , Nakai Naomasa , Balasubramanyam Ramesh , Hall Peter 
Published: March 2014

Abstract
We made a survey of water-vapor maser emission for 93 AGNs with the Nobeyama 45-m and Mopra 22-m telescopes from 1999 to 2002. A megamaser was detected in a Seyfert 2 galaxy, NGC 6926, at a distance of 80 Mpc, in 2002 June. [Greenhill et al. (2003a) have also reported a detection of the megamaser at the close date.] The peak flux density was 110 mJy, and the total isotropic luminosity was 340${L}_{\odot}$. The maser shows triply peaked spectrum, suggesting an edge-on disk. A narrow-line feature of the maser components at $V_{\mathrm{LSR}} = 6001 \,\mathrm{km} \,\mathrm{s}^{-1}$ was strongly variable with a time scale of a few tens of days, and the variation should be of intrinsic origin. We also showed a possibility of variability of water-vapor maser emission of a megamaser previously detected in a Seyfert/ultraluminous FIR galaxy, NGC 6240.
Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars
Authors: Takeda Yoichi , Hashimoto Osamu , Taguchi Hikaru , Yoshioka Kazuo , Takada-Hidai Masahide , Saito Yuji , Honda Satoshi 
Published: March 2014

Abstract
Extensive statistical-equilibrium calculations on S I and Zn I were carried out, in order to investigate how the non-LTE effect plays a role in the determination of their abundances in F–K stars. Having checked on the spectra of representative F-type stars (Polaris, Procyon, $\alpha$ Per) and the Sun that our non-LTE corrections yield a reasonable consistency between the abundances derived from different lines, we tried an extensive non-LTE reanalysis of published equivalent-width data of S I and Zn I lines for metal-poor halo/disk stars. According to our calculations, S I 9212/9228/9237 lines suffer significant negative non-LTE corrections ($\lesssim 0.2 \hbox{--} 0.3 \,\mathrm{dex}$), while LTE is practically valid for S I 8683/8694 lines. As far as the very metal-poor regime is concerned, a marked discordance is observed between the $\mathrm{[S/Fe]}$ values from these two abundance indicators, in the sense that the former attains a nearly flat plateau (or even a slight downward bending) while the latter shows an ever-increasing trend with a further lowering of metallicity. The characteristics of $\mathrm{[Zn/Fe]}$ reported from recent LTE studies (i.e., an evident/slight increase of $\mathrm{[Zn/Fe]}$ with a decrease of $\mathrm{[Fe/H]}$ for very metal-poor/disk stars) were almost confirmed, since the non-LTE corrections for the Zn I 4722/4810 and 6362 lines (tending to be positive and gradually increasing toward lower $\mathrm{[Fe/H]}$) are quantitatively of less significance ($\lesssim 0.1 \,\mathrm{dex}$).
Electron Impact Excitation of Ti XVIII
Authors: Zhong Jia Yong , Zeng Jiao Long , Zhao Gang , Bari Muhanmmud Abbas , Zhang Jie 
Published: March 2014

Abstract
Two different methods were used to calculate the collision strengths of boron-like titanium. One was a close-coupling way using the Dirac Atomic $R$-matrix Code (DARC) of P. H. Norrington and I. P. Grant (private communication), and the other was based on a relativistic distorted-wave (RDW) approximation with a Flexible Atomic Code (FAC) by Gu (2003). For DARC, the lowest 125 fine-structure levels belonging to the ($1s^{2}$) $2s^{2}2p, 2s2p^{2}, 2p^{3}, 2s^{2}3l, 2s2p3l$, and $2p^{2}3l$ ($l=s, p$, and $d$) configurations were included in the calculations. The target model space encompassed the lowest 15 levels, and all $105 \Delta n=0$ transitions together with 40 partial waves were included in calculations of the collision strengths. For FAC, the configuration interactions included in the calculations of atomic structure and excitation were among the same configurations of DARC. The collision strengths for all 125 levels were calculated at 10 scattered electron energies (10–10000 eV). The effective collision strengths, obtained after integrating the collision strengths of two codes over a Maxwellian distribution of electron energies, were also calculated for the electron temperatures in the range (50–500 eV). For application to spectral modeling or diagnostics, we report a complete set of data for the energy levels, radiative rates, and effective collision strengths (only FAC) for all transitions.
Detection of SiO Maser Emission in V838 Mon
Authors: Deguchi Shuji , Matsunaga Noriyuki , Fukushi Hinako 
Published: March 2014

Abstract
We report on the detection of 43 GHz SiO maser emission in V838 Mon, a prototype of a new class of eruptive variables, in which a red supergiant was formed after a nova-like eruption in 2002. The detection of SiO masers indicates that the star formed after the eruption is indeed a kind of cool mass-losing object with circumstellar masers. The measured radial velocity and the intensity of maser emission are consistent with the object being located at a distance of about 7 kpc from the sun. It also suggests that a considerable percentage of SiO masing objects in the Galaxy are formed by the same mechanism as that which created V838 Mon.
PPPM and TreePM Methods on GRAPE Systems for Cosmological N-Body Simulations
Authors: Yoshikawa Kohji , Fukushige Toshiyuki 
Published: March 2014

Abstract
We present Particle–Particle–Particle–Mesh (PPPM) and Tree Particle–Mesh (TreePM) implementations on GRAPE-5 and GRAPE-6A systems, special-purpose hardware accelerators for gravitational many-body simulations. In our PPPM and TreePM implementations on GRAPE, the computational time is significantly reduced compared with the conventional implementations without GRAPE, especially under strong particle clustering, and is almost constant irrespective of the degree of particle clustering. We describe our survey of two simulation parameters, the PM grid spacing and the opening parameter for the most optimal combination of force accuracy and computational speed. We also describe the parallelization of these implementations on a PC–GRAPE cluster, in which each node has one GRAPE board, and present the optimal configuration of simulation parameters for good parallel scalability.
An Unbiased Search for Molecular Clouds in the Southern Galactic Warp
Authors: Nakagawa Masanori , Onishi Toshikazu , Mizuno Akira , Fukui Yasuo 
Published: March 2014

Abstract
We made an unbiased search for molecular clouds in the Galactic Warp. This survey, covering an area of 56 square degrees at $l = 252^{\circ}$ to $266^{\circ}$ and $b =-5^{\circ}$ to $-1^{\circ}$, revealed 70 molecular clouds, while only 6 clouds were previously known in this sector at $R \gtrsim 14.5 \,\mathrm{kpc}$. The mass of the clouds is in a range from $7.8 \times 10^{2} \,{{{M}_{\odot}}}$ to $8.4 \times 10^{4} \,{{{M}_{\odot}}}$, significantly less than the most massive giant molecular clouds in the inner disk, $\sim 10^{6} \,{{{M}_{\odot}}}$, while the cloud mass spectrum characterized by a power law is basically similar to other parts of the Galaxy. The $X$ factor, $N(\mathrm{H}_{2}) / \int T({{12\atop} \mathrm{CO}}) \,dV$, derived from the molecular clouds in the Warp, is estimated to be $3.5(\pm1.8)$-times larger than that in the inner disk. The total molecular mass in the Warp is estimated to be $7.3 \times 10^5 \,{{{M}_{\odot}}}$, and the total mass in the far-outer Galaxy ($R \gtrsim 14.5 \,\mathrm{kpc}$) can be estimated to be $2 \times 10^7 \,{{{M}_{\odot}}}$. The spatial correlation between the CO and H i distribution appears to be fairly good, and the mass of the molecular gas is about 1% of that of the atomic gas in the far-outer Galaxy. This ratio is similar to that in the interarm, but is ten-times smaller than those of the spiral arms. Only 6 of the 70 Warp clouds show signs of star formation at the IRAS sensitivity, and the star-formation efficiency for high-mass stars in the Warp is found to be smaller than those in other molecular clouds in the Galaxy.
Apsidal Motion and Photometric Elements of the Eccentric Eclipsing Binary V401 Lacertae
Authors: Bulut Ibrahim , Demircan Osman 
Published: March 2014

Abstract
New UBV photometric observations of the recently discovered eccentric orbit binary V401 Lacertae were analyzed by using the Wilson-Devinney program. Seven new minimum times were estimated by using new observations. The analysis of the light curves and all available minimum times has revealed that the system is detached, with the orbital eccentricity $e = 0.1734 \pm 0.0003$, the longitude of the periastron $\omega = {63\rlap {.}{}^{\mathrm {\circ }}93} \pm {0\rlap {.}{}^{\mathrm {\circ }}15}$, the rate of change of the longitude of periastron $\dot{\omega} = {0\rlap {.}{}^{\mathrm {\circ }}0200} \pm {0\rlap {.}{}^{\mathrm {\circ }}0024} \;\mathrm{cycle}^{-1}$, corresponding to an apsidal motion period of $U = 96.2 \pm 11.4 \,\mathrm{yr}$. The apsidal motion of the system has been confirmed by the significant difference on the longitude of periastron ($\omega$) obtained from two light curves (Hipparcos and ourselves) in two different epochs.
Discovery of a Featureless X-Ray Spectrum in the Supernova Remnant Shell of G330.2+1.0
Authors: Torii Ken’ichi , Uchida Hiroyuki , Hasuike Kazuto , Tsunemi Hiroshi , Yamaguchi Yasuhiro , Shibata Shinpei 
Published: March 2014

Abstract
We report here on the first pointed X-ray observation of the supernova remnant (SNR) G330.2$+$1.0. The X-ray morphology is characterized by an extended shell. Its X-ray spectrum is well represented by a single power-law function with a photon index of $\gamma \simeq 2.8$ and interstellar absorption of $n_{\mathrm{H}} \simeq 2.6 \times 10^{22} \; [\mathrm{cm}^{-2}]$. We interpret this emission as synchrotron radiation from accelerated electrons at the SNR shock, as seen in SN 1006. The surface brightness of the X-ray emission is anti-correlated with the radio emission, and the power-law spectrum is dominated at the western shell where the radio emission is weak. The co-existence of two distinct (radio bright/X-ray faint and radio faint/X-ray bright) shells in a single supernova remnant challenges our understanding of the particle acceleration and radiation mechanisms in different interstellar environments. The object may be a good target for searching TeV gamma-rays and molecular gas surrounding the blast shock. We also report on the nature of a bright point-like source (AX J1601$-$5143) to the south of the SNR.
Ten Milliparsec-Scale Structure of the Nucleus Region in Centaurus A
Authors: Horiuchi Shinji , Meier David L. , Preston Robert A. , Tingay Steven J. 
Published: March 2014

Abstract
We present the results of a VLBI Space Observatory Programme (VSOP) observation of the subparsec structure in Cen A at 4.9 GHz. The observation produced an image of the subparsec jet components with a resolution of three-times better than images from previous VLBI monitoring campaigns at 8.4 GHz, and twice better than the previous 22 GHz studies. Owing to its proximity, our Cen A space-VLBI image is one of the highest spatial-resolution images of an AGN ever made—0.01 pc per beam—comparable only to the recent 43 GHz VLBI images of M87. The elongated core region is resolved into several components of over 10 milliarcsec long (0.2 pc), including a compact component of brightness temperature $2.2 \times 10^{10} \,\mathrm{K}$. A counterjet was detected: if we assume jet-counterjet symmetry, a relatively slow jet speed, and a large viewing angle, as derived from previous observations, the image allows us to investigate the distribution of ionized gas around the core, which is opaque at this frequency due to free-free absorption. We also analyzed the jet geometry in terms of collimation. Assuming the strongest component to be the core, the jet opening angle at $\sim 5000 \,r_{\mathrm{S}}$ from the core is estimated to be $\sim 12^\circ$, with the collimation of the jet to $\sim 3^\circ$ continuing out to $\sim 20000 \,r_{\mathrm{S}}$. This result is consistent with previous studies of the jet in M87, which favor MHD disk outflow models. Future space VLBI observations at higher frequencies will probably be able to image the collimation region, within $1000 \, r_{\mathrm{S}}$ of the center of Cen A, together with the accretion disk itself.
Milliarcsecond-Scale Spectral Properties and Jet Motions in M 87
Authors: Dodson Richard , Edwards Philip G. , Hirabayashi Hisashi 
Published: March 2014

Abstract
We have combined high resolution VLBI Space Observatory Programme (VSOP) data at 1.6 and 4.8 GHz with Very Long Baseline Array (VLBA) data at higher frequencies and with similar resolutions to study the spectral properties of the core of M 87 with milliarcsec resolution. The VSOP data allows a more accurate measurement of the turnover frequency, and hence more reliable determination of associated physical parameters of the source. Comparison of the images with previously published images yields no evidence for significant motions of components in the parsec-scale jet. In addition, the brightness temperatures obtained from modelfits to the core are well below the inverse Compton limit, suggesting that the radio emission we are observing is not strongly Doppler boosted.
Time Delays for the Giant Quadruple Lensed Quasar SDSS J1004+4112: Prospects for Determining the Density Profile of the Lensing Cluster
Authors: Kawano Yozo , Oguri Masamune 
Published: March 2014

Abstract
We investigated the dependence of the time delays for the large-separation gravitationally lensed quasar SDSS J1004$+$4112 on the inner mass profile of the lensing cluster. Adopting a mass model whose innermost density profile was parameterized as $\rho \propto r^{-\alpha}$, we derived a series of mass models that can fit the observational data, and then compute the probability distribution functions of time delays. We find that larger $\alpha$ has longer time delays, longer tails at the higher end of the probability distribution, and larger model uncertainties. The ratios of the time delays slightly depend on the slope, $\alpha$. Among others, time delays between images C and A (or B) have little dependence on the inner slope, particularly when the time delays are short. The dependence of time delays on $\alpha$ is well fitted by a linear form, which reflects the well-known degeneracy between the mass profile and time delays. We performed a Monte Carlo simulation to illustrate how well the inner slope can be constrained from measurements of time delays. We found that measurements of more than one time delay resulted in reasonably tight constraints on the inner slope ($\sigma_{\alpha} \lesssim 0.25$), while only one time delay could not determine the inner slope very well. Our result indicates that time delays indeed serve as a powerful tool to determine the mass profile, despite the complexity of the lensing cluster.
The Virgo High-Resolution CO Survey: VI. Gas Dynamics and Star Formation along the Bar in NGC 4303
Authors: Koda Jin , Sofue Yoshiaki 
Published: March 2014

Abstract
We present CO interferometer observations of the barred galaxy NGC 4303 (M 61). This galaxy has a strong gas concentration at the central region and prominent offset ridges at the leading sides of the bar. Sharp velocity gradients are apparent across the ridges. The brightness temperature in the ridges is low, indicating the existence of unresolved molecular clouds. Additionally, an analysis of the newborn stellar clusters revealed in HST images suggests that the parent molecular clouds had masses of $10^{4-6} \,{{{M}_{\odot}}}$. The observed shear velocity gradient across the ridges is too small to break up giant molecular clouds. Therefore, the clouds are likely to survive passage through the ridges. We discuss a cloud orbit model in a bar potential for understanding the gas distribution, dynamics, and star formation in NGC 4303. The model reproduces the narrow offset ridges and sharp velocity gradients across the ridges, although no shock is associated with the ridges. We discuss cloud–cloud collisions (and close interactions) as a possible triggering mechanism for star formation. The newborn stellar clusters in NGC 4303 are located predominantly at the leading sides of the offset ridges. Cloud orbits are densely populated in the region where the clusters are found, suggesting a high collisional frequency and possibly a high rate of triggered star formation. Cloud-based dynamics is less dissipative than smooth hydrodynamic models, possibly extending the timescales of gas dynamical evolution and gas fueling to central regions in barred galaxies.
Superhumps Behavior during Normal Outbursts in ER Ursae Majoris: Spectroscopy and Photometry
Authors: Zhao Yinghe , Li Zongyun , Wu Xiaoan , Peng Qiuhe , Zhang Zhousheng , Li Zili 
Published: March 2014

Abstract
We undertook a 4-day spectroscopic observation and conducted a 13-day photometric study of an SU UMa-type dwarf nova, ER Ursae Majoris. The mean $K$-amplitude for the emission lines is $54 \pm 8 \,\mathrm{km} \,\mathrm{s}^{-1}$ and the $\gamma$ velocity is $8 \pm 4 \,\mathrm{km} \,\mathrm{s}^{-1}$ based on our spectroscopic results. A phase shift of 0.22 was also obtained. Our photometric observation confirms superhumps in normal outbursts of ER UMa, and reconciles contradictory observational results obtained by different authors. We find that superhumps possibly develop near each normal outburst maximum and fade out before the next outburst maximum. If the observed humps were not late superhumps, but ordinary superhumps, much more theoretical work should be done to explain the new phenomena.