bluuebunny/crossref_metadata_2025_split huggingface dataset:
Horizontal and Vertical Flow Structure in Emerging Flux Regions
Authors: Kozu Hiromichi , Kitai Reizaburo , Brooks David H. , Kurokawa Hiroki , Yoshimura Keiji , Berger Thomas E. 
Published: March 2014

Abstract
In order to obtain an overall view of the flow structure of convective gas in emerging flux regions (EFRs), we studied three EFRs in two solar active regions, NOAA 8218 and NOAA 10774. Using the Local Correlation Tracking method, we found several horizontally divergent flow structures, which were stable over a period of 1 hour, in 2 EFRs in NOAA 8218. The horizontal flow velocities and the sizes of the structures were around $500 \,\mathrm{m} \,\mathrm{s}^{-1}$ and about 4 mm in radius, respectively. We analyzed another dataset of NOAA 10774 using spectroscopic methods and found temporarily stable up-ward gas flows in the central part of the EFR. The line-of-sight velocities were around $150 \,\mathrm{m} \,\mathrm{s}^{-1}$ and the size of the flow patch was 2 to 5 mm in radius. These results support our previous findings that convective-cell-like flow appears in the central part of an EFR. We estimated from these results that the depth of the flow cell in EFRs is about 600 Km, and the turn-over time of the cell is about 2 hours.
Monte Carlo Modeling of Compton-Scattering Angles in a Mildly Relativistic Plasma
Authors: Seon Kwang-Il 
Published: March 2014

Abstract
If the inversion method is applied to random-number generation in a Monte Carlo simulation of Compton-scattering, we often encounter cubic equations. These may be solved using well-known numerical iterative methods, such as the Newton–Raphson, or bisection methods. These numerical methods, however, may lead to many iterations, which should be avoided for modeling efficiency. We present explicit inversion formulae of two cubic equations arising from the modeling of Compton-scattering angles in a mildly or weakly relativistic plasma. Explicit analytical methods are superior to any other rejection or numerical inversion methods in terms of the modeling efficiency, and will be useful for Monte Carlo simulations of X-ray reflection from cold material and the Sunyaev–Zel’dovich effect.
Implications for Cosmic Reionization from the Optical Afterglow Spectrum of the Gamma-Ray Burst 050904 at z = 6.3
Authors: Totani Tomonori , Kawai Nobuyuki , Kosugi George , Aoki Kentaro , Yamada Toru , Iye Masanori , Ohta Kouji , Hattori Takashi 
Published: March 2014

Abstract
The gamma-ray burst (GRB) 050904 at $z = 6.3$ provides the first opportunity to probe the intergalactic medium (IGM) by GRBs at the epoch of reionization. Here, we present a spectral modeling analysis of the optical afterglow spectrum taken by the Subaru Telescope, aiming to constrain the reionization history. The spectrum shows a clear damping wing at wavelengths redward of the Lyman break, and the wing shape can be fitted either by a damped Ly$\alpha$ system with a column density of $\log [N_{\mathrm{H {I}}} \,(\mathrm{cm}^{-2})] \sim 21.6$ at a redshift close to the detected metal absorption lines ($z_{\mathrm{metal}} = 6.295$), or by almost neutral IGM extending to a slightly higher redshift of $z_{\mathrm{IGM,u}} \sim 6.36$. In the latter case, the difference between the two redshifts may be explained by the acceleration of metal absorbing shells in the activities of the GRB or its progenitor. However, we exclude this possibility by using the light transmission feature around the Ly$\beta$ resonance, leading to a firm upper limit of $z_{\mathrm{IGM,u}} \leq 6.314$. We then show evidence that the IGM was already largely ionized at $z = 6.3$ with the best-fit neutral fraction of IGM, $x_{\mathrm{H {I}}} \; (\equiv n_{\mathrm{H {I}}} / n_{\mathrm{H}}) = 0.00$, and upper limits of $x_{\mathrm{H {I}}} &lt; 0.17$ and 0.60 at 68% and 95% confidence levels, respectively. This is the first direct and quantitative upper limit on $x_{\mathrm{H {I}}}$ at $z \gt 6$. Various systematic uncertainties are examined, but none of them appears large enough to change our conclusion. To get further information on the reionization, it is important to increase the sample size of $z \gtrsim 6$ GRBs, in order to find GRBs with low column densities ($\log N_{\mathrm{H {I}}} \lesssim 20$) within their host galaxies and to make statistical studies of Ly$\alpha$ line emission from host galaxies.
Optical Monitoring of the Seyfert Galaxy NGC 4151 from 1997 to 2003
Authors: Guo Difu , Tao Jun , Qian Bochen 
Published: March 2014

Abstract
CCD photometric observations ($V, R$, and $I$) of the Seyfert galaxy NGC 4151 were carried out from 1997 May 9 to 2003 May 25. A possible microvariation was found simultaneously in three bands on 2003 May 2. If the microvariation was due to a hot spot on the accretion disk, then there is probably a supermassive black hole of around $5.4 \times 10^7 \,{{{M}_{\odot}}}$ at the center of the source. Combining our new data and data from literature, the historical light curves from 1968 to 2003 ($V$ band) and from 1910 to 2000 ($B$ band) were compiled and used to study the periodicity of the source. A possible period of around 15.8 yr was found.
Common Correlations between 60, 100, and 140$\, {\mu \mathrm {m}}$ Intensities in the Galactic Plane and Magellanic Clouds
Authors: Hibi Yasunori , Shibai Hiroshi , Kawada Mitsunobu , Ootsubo Takafumi , Hirashita Hiroyuki 
Published: March 2014

Abstract
We investigated the far-infrared SED of the Galaxy and the Magellanic Clouds by using the COBE (COsmic Background Explorer)/DIRBE (Diffuse InfraRed Background Experiment) ZSMA (Zodi-Subtracted Mission Average) maps at wavelengths of 60$\, {\mu \mathrm {m}}$, 100$\, {\mu \mathrm {m}}$, and 140$\, {\mu \mathrm {m}}$. We analyzed three regions: the galactic plane region with the galactic latitude $\vert b\vert &lt; 5^{\circ}$, the Large Magellanic Cloud region, and the Small Magellanic Cloud region. Because the dust optical depth is much smaller in the far-infrared than in the visible, we could observe cumulative far-infrared radiation from regions with various interstellar radiation field in the line of sight. As a consequence of considering such an effect, we found a common far-infrared color correlation between the 140–100$\, {\mu \mathrm {m}}$ and 100–60$\, {\mu \mathrm {m}}$ intensity ratios in all three galaxies. Although this color correlation cannot be explained by any existing model, it fits very well the far-infrared color of nearby star-forming galaxies.
Energy Conversion Efficiency in Prompt Emissions of Gamma-Ray Bursts
Authors: Suzuki Motoko , Kawai Nobuyuki 
Published: March 2014

AbstractUsing 52 gamma-ray bursts observed and localized by BeppoSAX and HETE-2, a comprehensive analysis of the correlation between the properties of prompt emissions and the brightness of the afterglows was performed. We found a highly significant correlation between the isotropic total energy of prompt emission and luminosity of optical afterglow. There is also a correlation between the fluence in prompt emission and the magnitude of the optical afterglow. We then investigated the energy conversion efficiency in prompt emissions of gamma-ray bursts using 24 bursts with the known redshift. We calculated the kinetic energy of relativistic shells from the luminosities of the optical afterglows. The energy-conversion efficiency, as estimated by comparing this kinetic energy with the total radiated energy of prompt emission, is distributed between about 1% and 40%. This result suggests that the ratio of the Lorentz factor of two colliding shells is large, or the fraction of shock energy that goes into the electrons is small for the internal shock scenario.
Dynamical Friction on Satellite Galaxies
Authors: Fujii Michiko , Funato Yoko , Makino Junichiro 
Published: March 2014

Abstract
For a rigid model satellite, Chandrasekhar’s dynamical friction formula describes the orbital evolution quite accurately, when the Coulomb logarithm is chosen appropriately. However, it is not known if the orbital evolution of a real satellite with the internal degree of freedom can be described by the dynamical friction formula. We performed an $N$-body simulation of the orbital evolution of a self-consistent satellite galaxy within a self-consistent parent galaxy. We found that the orbital decay of the simulated satellite is significantly faster than an estimate from the dynamical friction formula. The main cause of this discrepancy is that the stars stripped out of the satellite are still close to the satellite, and increase the drag force on the satellite through two mechanisms. One is a direct drag force from particles in the trailing tidal arm, a non-axisymmetric force that slows the satellite down. The other is an indirect effect that is caused by the particles remaining close to the satellite after escaping. The force from them enhances the wake caused in the parent galaxy by dynamical friction, and this larger wake in turn slows the satellite down more than expected from the contribution of its bound mass. We found that these two have comparable effects, and that the combined effect can be as large as 20% of the total drag force on the satellite.
Discovery of a New Dwarf Nova, TSS J022216.4+412259.9: WZ Sge-Type Dwarf Nova Breaking the Shortest Superhump Period Record
Authors: Imada Akira , Kubota Kaori , Kato Taichi , Nogami Daisaku , Maehara Hiroyuki , Nakajima Kazuhiro , Uemura Ryoko Ishioka Makoto 
Published: March 2014

Abstract
We report on the time-resolved CCD photometry of a newly discovered variable star, TSS J022216.4$+$412259.9 during an outburst in a 2005 November–December brightening. The obtained light curves unambiguously show 0.2–0.3 mag modulations, which we confirmed to be the superhump observed among SU UMa-type dwarf novae. We also performed a period search for data obtained during the outburst plateau phase, and revealed the existence of the two periodicities: 0.054868(98)d for the first two nights and 0.055544(26)d for the following plateau phase. This bi-periodicity is hardly observed in the usual SU UMa-type dwarf novae, but is characteristic of WZ Sge-type stars. We undoubtedly detected a rebrightening in the post-outburst stage, which is typical of short-period SU UMa-type dwarf novae, including WZ Sge-type stars. These observations suggest that TSS J022216.4$+$412259.9 may be a new WZ Sge star breaking the shortest superhump period so far of 0.05648 d for V592 Her among this class with a known superhump period.
Infrared 2–4 Micrometer Spectroscopy and Millimeter Interferometric HCN and HCO+ Observations of the Individual Merging Components of Arp 299
Authors: Imanishi Masatoshi , Nakanishi Kouichiro 
Published: March 2014

Abstract
We present ground-based infrared $K$–(2–2.5$\, {\mu \mathrm {m}}$) and $L$-band (2.8–4.1$\, {\mu \mathrm {m}}$) spectroscopy, as well as interferometric observations at $\lambda \sim 3 \,\mathrm{mm}$, for the individual merging components (A, B, and C) of the luminous infrared galaxy Arp 299. The presence and location of a buried active galactic nucleus (AGN) are investigated. Our sub-arcsec-resolution infrared spectra clearly reveal that the putative buried AGN resides in the nucleus B1 (a subcomponent of B), based on a very low equivalent width of 3.3$\, {\mu \mathrm {m}}$ polycyclic aromatic hydrocarbon emission, a weak 2.3$\, {\mu \mathrm {m}}$ CO absorption feature, and a large time variation of the $K$–and $L$-band continuum fluxes. Our interferometric observations simultaneously obtain HCN ($J = 1 \hbox{--} 0$) and $\mathrm{HCO}^{+}$ ($J = 1 \hbox{--} 0$) emission lines with $\sim 4 {{}^{\prime \prime }}$ resolution, and we find the HCN to $\mathrm{HCO}^{+}$ brightness-temperature ratios to be as low as those found in starburst nuclei in all of the major merging components of Arp 299. The low ratio even in the AGN-hosting nucleus B may be due to the presence of a large amount of high-density molecular gas whose chemistry is dominated by coexisting starbursts and/or shocks, rather than by the central strong X-ray-emitting AGN.
Probable Association of T Tauri Stars with the L 1014 Dense Core
Authors: Morita Atsuko , Watanabe Makoto , Sugitani Koji , Itoh Yoichi , Uehara Mariko , Nagashima Chie , Ebizuka Noboru , Hasegawa Takashi , Kinugasa Kenzo , Tamura Motohide 
Published: March 2014

Abstract
Using the Wide Field Grism Spectrograph 2 (WFGS2), we carried out slit-less spectroscopy, $g'r'i'$ photometry, and slit spectroscopy on the L 1014 dense core. We detected three $\mathrm{H}\alpha$ emission-line stars. We interpret one as being a weak-line T Tauri star (WTTS) and the others as classical T Tauri stars (CTTS). Since their $g'-i'$ colors and/or classified spectral types are consistent with those of T Tauri stars and two of them show less extinction than the cloud, these three stars are likely to be T Tauri stars associated with L 1014. Adopting an age range for T Tauri stars, 1–10 Myr, the color–magnitude diagram suggests a distance of $\sim 400 \hbox{--} 900 \,\mathrm{pc}$, rather than the previously assumed distance, 200 pc. This could strongly affect the mass estimate of L 1014-IRS, which is thought to be either a very young protostar or proto-brown dwarf.
CO (3–2) and CO (2–1) Detections in a z = 1.3 Hyper-Luminous Starburst Galaxy
Authors: Iono Daisuke , Tamura Yoichi , Nakanishi Kouichiro , Kawabe Ryohei , Kohno Kotaro , Okuda Takeshi , Yamada Kenkichi , Hatsukade Bunyo , Sameshima Masahiro 
Published: March 2014

Abstract
We present an $\sim 2^{\prime\prime}$ resolution image of the CO (2–1) emission and an $\sim 4^{\prime\prime}$ resolution image of the CO (3–2) emission in the $z=1.3$ hyper-luminous starburst galaxy MIPS J142824.0$+$352619, obtained at the Nobeyama Radio Observatory. Our new CO (3–2) and CO (2–1) emission detections yield $L'_{\mathrm{CO}\,(3 \hbox{--} 2)} = 1.4 \; (\pm 0.5) \times 10^{11}$ and $L'_{\mathrm{CO}\,(2 \hbox{--}1)} = 1.2 \; (\pm 0.3) \times 10^{11} \,\mathrm{K} \,\mathrm{km} \,\mathrm{s}^{-1} \,\mathrm{pc}^2$, which translate to a molecular gas mass of $\sim 10^{11} \,{{{M}_{\odot}}}$, assuming a CO to $\mathrm{H}_2$ conversion factor appropriate for ULIRGs. The derived high CO luminosities place this source as being one of the brightest galaxies detected in CO to date. The CO (3–2) and CO (2–1) derived redshifts are $1.3248 \pm 0.0002$ and $1.3250 \pm 0.0002$. If the bulk of the molecular gas traced in these lines is completely thermalized, as suggested by $L'_{\mathrm{CO}\,(3 \hbox{--} 2)} / L'_{\mathrm{CO}\,(2 \hbox{--}1)} \sim 1$, a constraint to the gas density of $n \gtrsim 10^3 \,\mathrm{cm}^{-3}$ is obtained from our Large Velocity Gradient (LVG) analysis. If a significant fraction of the bright FIR luminosity of $L_{\mathrm{FIR}} = (3.2 \pm 0.7) \times 10^{13} \,{{{L}_{\odot}}}$ arises from starburst activity, then the Star Formation Efficiency (SFE) is $320 \,{{{L}_{\odot}}} \,M_{ {\odot }}^{-1}$. The size constraint of ${1\rlap {.}{}^{\mathrm {\prime \prime }}3}$ given by the CO (2–1) map provides an upper limit to the lensing magnification factor of $\mu \lesssim 8$, which further supports the earlier claim that the magnification of this source is only modest.
Nobeyama CO Atlas of Nearby Spiral Galaxies: Distribution of Molecular Gas in Barred and Nonbarred Spiral Galaxies
Authors: Kuno Nario , Sato Naoko , Nakanishi Hiroyuki , Hirota Akihiko , Tosaki Tomoka , Shioya Yasuhiro , Sorai Kazuo , Nakai Naomasa , Nishiyama Kota , Vila-VilarÓ Baltsar 
Published: March 2014

Abstract
The data from a CO ($J$ = 1–0) mapping survey of 40 nearby spiral galaxies, performed with the Nobeyama 45 m telescope, are presented. The criteria of the sample selection were: (1) RC3 morphological type ranging from Sa to Scd, (2) distance of less than 25 Mpc, (3) inclination angle less than 79$^{\circ}$ (RC3), (4) flux at 100$\mu$m higher than $\sim$ 10 Jy, and (5) spiral structure not destroyed by any interaction. The maps of CO cover most of the optical disk of the galaxies. We investigated the influence of bars on the distribution of molecular gas in spiral galaxies using these data. We confirmed that the degree of the central concentration is higher in barred spirals than in nonbarred spirals, as shown by previous studies. Furthermore, we present observational evidence that bars are efficient in driving molecular gas that lies within the bar length toward the center, while the role in bringing gas in from the outer parts of the disks is small. The transported gas accounts for about half of the molecular gas within the central region in barred spiral galaxies. We found a correlation between the degree of central concentration and the bar strength. Galaxies with stronger bars tend to have a higher central concentration. The correlation implies that stronger bars accumulate molecular gas toward the center more efficiently. These results are consistent with long-lived bars.
Relativistic Effects on the Observed AGN Luminosity Distribution
Authors: Liu Yuan , Zhang Shuang Nan , Zhang Xiao Ling 
Published: March 2014

Abstract
Recently, Zhang (2005 ApJ, 618, L79) has proposed a model to account for the well-established effect that the fraction of type-II AGNs is anti-correlated with the observed X-ray luminosity; the model consists of an X-ray emitting accretion disk coaligned to the dusty torus within the standard AGN unification model. In this paper the model is refined by including relativistic effects of the observed X-ray radiation from the vicinity of the supermassive black hole in an AGN. The relativistic corrections improve the combined fitting results of the observed luminosity distribution and the type-II AGN fraction, though the improvement is not significant. The type-II AGN fraction prefers non–or mildly spinning black hole cases, and rules out the extremely spinning case.
Age Sequence in Small Clusters Associated with Bright-Rimmed Clouds
Authors: Ogura Katsuo , Chauhan Neelam , Pandey Anil K. , Bhatt Bhuwan C. , Ojha Devendra , Itoh Yoichi 
Published: March 2014

Abstract
Bright-rimmed clouds (BRCs) found in HII regions are probable sites of triggered star formation due to compression by ionization/shock fronts, and it is hypothesized that star formation proceeds from the exciting star(s) side outward of the HII region (“small-scale sequential star formation”). In order to quantitatively test this hypothesis we undertook $BVI_\mathrm{c}$ photometry of four BRC aggregates. The amounts of interstellar extinction and reddening for each star were estimated by using $JHK_\mathrm{s}$ photometry. We then constructed reddening-corrected $V/V-I_\mathrm{c}$ color-magnitude diagrams, where the age of each star was derived. All of the stars turned out to be a few tenths to a few Myr old. Although the scatters were large and the numbers of the sample stars are small, we found a clear trend that the stars inside or in the immediate vicinity of the bright rim are younger than those outside it in all four aggregates, confirming the hypothesis in question.
Subarcsecond Near-Infrared Images of Massive Star Formation Region NGC 6334 V
Authors: Hashimoto Jun , Tamura Motohide , Suto Hiroshi , Abe Lyu , Ishii Miki , Kudo Tomoyuki , Mayama Satoshi 
Published: March 2014

Abstract
We present high spatial resolution (0$\rlap{.}^{\prime\prime}3$) polarimetric images in the $H$ and $K$ bands and direct images in the $L'$ and $M'$ bands of the NGC 6334 V infrared nebulae. The images show complex structures including the multishells and various knots in the nebulae. The appearances and colors of the eastern and western nebulae differ considerably. Our polarization images also show differences between the illuminating sources of the nebulae: the eastern nebula is illuminated by a deeply embedded mid-infrared source, KDJ 4, and the western nebula by our newly detected near-infrared source, WN-A1. The degree of polarization of the nebulae is very large, up to 70% at $K$ and 60% at $H$, which is consistent with a single scattering of near-infrared radiation from each source at the walls of the mass outflows.
Physical Conditions of Molecular Gas in the Galactic Center
Authors: Nagai Makoto , Tanaka Kunihiko , Kamegai Kazuhisa , Oka Tomoharu 
Published: March 2014

Abstract
We estimated the physical conditions of molecular gas in the central molecular zone (CMZ) of the Galaxy, using our CO $J = 3-2$ data obtained with the Atacama Submillimeter Telescope Experiment (ASTE) in conjunction with J = 1–0 $^{12}$CO and $^{13}$CO data previously observed with the Nobeyama Radio Observatory (NRO) 45 m telescope. The large velocity gradient (LVG) approximation was employed. The distributions of gas density, kinetic temperature, and CO column density were derived as functions of the position and the velocity for the entire coverage of the CO $J = 3-2$ data. We fairly determined the physical conditions for 69% of data points in the CMZ with $\geq 1 \hskip2pt\sigma$ CO detections. The kinetic temperature was found to be roughly uniform in the CMZ, while the gas density was higher in the 120 pc star-forming ring than in the outer dust lanes. The physical conditions of high $J = 3-2/J = 1-0$ features are also discussed.
ASTE Observations of Nearby Galaxies: A Tight Correlation between CO J = 3–2 Emission and H$\alpha$
Authors: Komugi Shinya , Kohno Kotaro , Tosaki Tomoka , Nakanishi Hiroyuki , Onodera Sachiko , Egusa Fumi , Sofue Yoshiaki 
Published: March 2014

Abstract
Star formation rates (SFRs) obtained via extinction-corrected H$\alpha$ are compared to dense gas, as traced by $^{12}{\rm CO}$ (J = 3–2) emission at the centers of nearby galaxies, observed with the ASTE telescope. It is found that, although many of the observed positions are dusty, and therefore heavily absorbed at H$\alpha$, the SFR shows a striking correlation with dense gas in the form of the Schmidt law with an index of 1.0. The correlation is also compared between gas traced by $^{12}{\rm CO}$ (J = 1–0) and the application of an H$\alpha$ extinction correction. We find that dense gas produces a far-better correlation with SFR in view of the surface density values.
ASTE 12CO (J = 3–2) Survey of Elliptical Galaxies
Authors: Nakanishi Hiroyuki , Tosaki Tomoka , Kohno Kotaro , Sofue Yoshiaki , Kuno Nario 
Published: March 2014

Abstract
We report on $^{12}$CO ($J$ = 3–2) observations of 15 nearby elliptical galaxies, carried out with the ASTE telescope. Thirteen were selected without regard to the presence of other tracers of cold interstellar matter. CO emission was detected from three of the galaxies, two of which were undetected by IRAS at 100 $\mu$m. The molecular gas masses range from $2.2 \times 10^6$ to $4.3 \times 10^8 M_\odot$. The ratio of the CO (3–2) and (1–0) lines, $R_{31}$, has a lower value for elliptical galaxies than for spiral galaxies, except for NGC 855, for which the value is close to the mean for spirals. The molecular gas in NGC 855 has a mean density in the range of 300–1000 cm$^{-3}$, adopting a temperature range of 15–100 K.