bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discovery of a Possible X-Ray Counterpart to HESS J1804—216
Authors: Bamba Aya , Koyama Katsuji , Hiraga Junko S. , Hughes John P. , Kohmura Takayoshi , Kokubun Motohide , Maeda Yoshitomo , Matsumoto Hironori , Senda Atsushi , Takahashi Tadayuki , Tsuboi Yohko , Yamauchi Shigeo , Yuasa Takayuki 
Published: March 2014

Abstract
Suzaku deep observations have discovered two highly significant nonthermal X-ray sources, Suzaku J1804$-$2142 (Src 1) and Suzaku J1804$-$2140 (Src 2), positionally coincident with the unidentified TeV $\gamma$-ray source, HESS J1804$-$216. The X-ray sources are not time variable and show no counterpart in other wavebands, except for the TeV source. Src 1 is unresolved at Suzaku spatial resolution, whereas Src 2 is extended or composed of multiple sources. The X-ray spectra are highly absorbed, hard, and featureless, and are well fitted by absorbed power-law models with best-fit photon indices and absorption columns of $-0.3_{-0.5}^{+0.5}$ and $0.2_{-0.2}^{+2.0} \times 10^{22} \,\mathrm{cm}^{-2}$ for Src 1, and $1.7_{-1.0}^{+1.4}$ and $1.1_{-0.6}^{+1.0} \times 10^{23} \,\mathrm{cm}^{-2}$ for Src 2. The measured X-ray absorption to the latter source is significantly larger than the total Galactic neutral hydrogen column in that direction. The unabsorbed 2–10 keV band luminosities are $7.5 \times 10^{32} (d/5 \,\mathrm{kpc})^2 \,\mathrm{erg} \,\mathrm{s}^{-1}$ (Src 1) and $1.3 \times 10^{33} (d/5 \,\mathrm{kpc})^2 \,\mathrm{erg} \,\mathrm{s}^{-1}$ (Src 2), where $d$ is the source distance. Among the handful of TeV sources with known X-ray counterparts, HESS J1804$-$216 has the largest ratio of TeV $\gamma$-ray to hard X-ray fluxes. We discuss the nature of the emission and propose the Suzaku sources as plausible counterparts to the TeV source, although further observations are necessary to confirm this.
Precision Fe Kα and Fe Kβ Line Spectroscopy of the Seyfert 1.9 Galaxy NGC 2992 with Suzaku
Authors: Yaqoob Tahir , Murphy Kendrah D. , Griffiths Richard E. , Haba Yoshito , Inoue Hajime , Itoh Takeshi , Kelley Richard , Kokubun Motohide , Markowitz Alex , Mushotzky Richard , Okajima Takashi , Ptak Andrew , Reeves James , Serlemitsos Peter J. , Takahashi Tadayuki , Terashima Yuichi 
Published: March 2014

Abstract
We present detailed time-averaged X-ray spectroscopy in the 0.5–10 keV band of the Seyfert 1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometer (XIS). There is an Fe K line emission complex that we model with broad and narrow lines and we show that the intensities of the two components are decoupled at a confidence level $ \gt3\sigma$. The broad line ($\mathrm{EW} = 118^{+32}_{-61} \,\mathrm{eV}$) could originate in an accretion disk (inclined at $ \gt30^{\circ}$). The narrow Fe $\mathrm{K}\alpha$ line ($\mathrm{EW} =163^{+47}_{-26} \,\mathrm{eV}$) is unresolved by the XIS at 99% confidence and likely originates in distant matter. A significant (narrow) Fe $\mathrm{K}\beta$ line is also detected and we describe a new robust method to constrain the ionization state of Fe in the distant line emitter (e.g. the putative obscuring torus). The method does not require any knowledge of possible gravitational and Doppler energy shifts and we deduce that the predominant ionization state of Fe in the distant matter is lower than Fe VIII (at 99% confidence), conservatively taking into account residual calibration uncertainties and theoretical and experimental uncertainties in the Fe K fluorescent line energies. We argue that the narrow Fe $\mathrm{K}\alpha$ and Fe $\mathrm{K}\beta$ lines likely originate in a Compton-thin structure.
The Suzaku High Resolution X-Ray Spectrometer
Authors: Kelley Richard L. , Mitsuda Kazuhisa , Allen Christine A. , Arsenovic Petar , Audley Michael D. , Bialas Thomas G. , Boyce Kevin R. , Boyle Robert F. , Breon Susan R. , Brown Gregory V. , Cottam Jean , DiPirro Michael J. , Fujimoto Ryuichi , Furusho Tae , Gendreau Keith C. , Gochar Gene G. , Gonzalez Oscar , Hirabayashi Masayuki , Holt Stephen S. , Inoue Hajime , Ishida Manabu , Ishisaki Yoshitaka , Jones Carol S. , Keski-Kuha Ritva , Kilbourne Caroline A. , McCammon Dan , Morita Umeyo , Moseley S. Harvey , Mott Brent , Narasaki Katsuhiro , Ogawara Yoshiaki , Ohashi Takaya , Ota Naomi , Panek John S. , Porter F. Scott , Serlemitsos Aristides , Shirron Peter J. , Sneiderman Gary A. , Szymkowiak Andrew E. , Takei Yoh , Tveekrem June L. , Volz Stephen M. , Yamamoto Mikio , Yamasaki Noriko Y. 
Published: March 2014

Abstract
The X-Ray Spectrometer (XRS) has been designed to provide the Suzaku Observatory with non-dispersive, high-resolution X-ray spectroscopy. As designed, the instrument covers the energy range 0.3 to 12 keV, which encompasses the most diagnostically rich part of the X-ray band. The sensor consists of a 32-channel array of X-ray microcalorimeters, each with an energy resolution of about 6 eV. The very low temperature required for operation of the array (60 mK) is provided by a four-stage cooling system containing a single-stage adiabatic demagnetization refrigerator, a superfluid-helium cryostat, a solid-neon dewar, and a single-stage, Stirling-cycle cooler. The Suzaku/XRS is the first orbiting X-ray microcalorimeter spectrometer and was designed to last more than three years in orbit. The early verification phase of the mission demonstrated that the instrument worked properly and that the cryogen consumption rate was low enough to ensure a mission lifetime exceeding 3 years. However, the liquid-He cryogen was completely vaporized two weeks after opening the dewar guard vacuum vent. The problem has been traced to inadequate venting of the dewar He and Ne gases out of the spacecraft and into space. In this paper we present the design and ground testing of the XRS instrument, and then describe the in-flight performance. An energy resolution of 6 eV was achieved during pre-launch tests and a resolution of 7 eV was obtained in orbit. The slight degradation is due to the effects of cosmic rays.
Star-Forming Galaxies at z ≈ 0.24 in the Subaru Deep Field and the Sloan Digital Sky Survey
Authors: Morioka Taichi , Nakajima Aki , Taniguchi Yoshiaki , Shioya Yasuhiro , Murayama Takashi , Sasaki Shunji S. 
Published: March 2014

Abstract
We made a search for H$\alpha $ emitting galaxies at z$\approx $ 0.24 in the Subaru Deep Field (SDF) using an archival data set obtained with the Subaru telescope. We carefully selected H$\alpha $ emitters in the narrow-band filter NB816, using $B$, $V$, $R_{\rm C}$, $i^\prime$, and z$^\prime$ broad-band colors. We obtained a sample of 258 emitting galaxies with observed equivalent widths of (H$\alpha $$+$ [NII]6548,6584) greater than 12Å. We also analyzed a sample of H$\alpha $ emitters taken from the Sloan Digital Sky Survey (SDSS) to constrain the luminous end of the H$\alpha $ luminosity function. Using the same selection criteria as those for the SDF, and after excluding AGNs, we obtained 317 H$\alpha $ emitting star-forming galaxies. Combining these two samples of H$\alpha $ emitters found in both SDF and SDSS, we derived an H$\alpha $ luminosity function with best-fit Schechter function parameters of $\alpha $$=$$-$1.31$^{+0.17}_{-0.17}$, log$\phi^{*}$$=$$-$2.46$^{+0.34}_{-0.40}$Mpc$^{-3}$, and log$L^{*}$$=$ 41.99$^{+0.08}_{-0.07}$ergss$^{-1}$. The extinction-corrected H$\alpha $ luminosity density is 4.45$^{+2.96}_{-1.75}$$\times$ 10$^{39}$ergss$^{-1}$Mpc$^{-3}$. Using the Kennicutt relation between the H$\alpha $ luminosity and star-formation rate, the star-formation rate density in the survey volume was estimated at 0.035$^{+0.024}_{-0.014}M_{\odot}$yr$^{-1}$Mpc$^{-3}$. The angular two-point correlation function of H$\alpha $ emitters over 875 arcmin$^2$ at z$=$ 0.24 was well-fitted by a power-law form with $w(\theta)$$=$ 0.047$^{+0.017}_{-0.013} \theta^{-0.66 \pm 0.08}$, corresponding to the correlation function $\xi(r)$$=$ [$r/$(2.6$^{+1.0}_{-0.8}$Mpc)]$^{-1.66\pm0.08}$. The small correlation length of H$\alpha $ emitters may imply a weak clustering of active star-forming galaxies.
Clustering Properties of Low-Luminosity Star-Forming Galaxies at z = 0.24 and 0.40 in the Subaru Deep Field
Authors: Nakajima Aki , Shioya Yasuhiro , Nagao Tohru , Saito Tomoki , Murayama Takashi , Sasaki Shunji S. , Yokouchi Asuka , Taniguchi Yoshiaki 
Published: March 2014

Abstract
We present our analysis on the clustering properties of star-forming galaxies selected by narrow-band excesses in the Subaru Deep Field. Specifically, we focus on H$\alpha $ emitting galaxies at $z$$=$ 0.24 and $z$$=$ 0.40 in the same field, to investigate possible evolutionary signatures of clustering properties of star-forming galaxies. Based on an analysis on 228 H$\alpha $ emitting galaxies with 39.8 $\lt$ log$L$(H$\alpha $) $\lt$ 40.8 at $z$$=$ 0.40, we find that their two-point correlation function can be estimated as $\xi$$=$ ($r/$1.62$^{+0.64}_{-0.50}$Mpc)$^{-1.84\pm0.08}$. This is similar to that of H$\alpha $ emitting galaxies in the same H$\alpha $ luminosity range at $z$$=$ 0.24, $\xi$$=$ ($r/$1.88$^{+0.60}_{-0.49}$Mpc)$^{-1.89 \pm0.07}$. These correlation lengths are smaller than those for a brighter galaxy sample studied by Meneux et al. (2006) in the same redshift range. The evolution of the correlation length between $z$$=$ 0.24 and $z$$=$ 0.40 is interpreted by the gravitational growth of the dark-matter halos.
Detection of Polarimetric Variations Associated with the Shortest Time-Scale Variability in S5 0716+714
Authors: Sasada Mahito , Uemura Makoto , Arai Akira , Fukazawa Yasushi , Kawabata Koji S. , Ohsugi Takashi , Yamashita Takuya , Isogai Mizuki , Sato Shuji , Kino Masaru 
Published: March 2014

Abstract
We present the results of near-infrared and optical observations of the BL Lac object S5 0716$+$714, carried out with the KANATA telescope. S5 0716$+$714 has both a long-term, high-amplitude variability and a short-term variability within one night. The shortest variability (microvariability) time-scale is important for understanding the geometry of jets and the magnetic field, because it provides a possible minimum size of variation sources. Here, we report on the detection of 15-min variability in S5 0716$+$714, which is one of the shortest time scales in optical and near-infrared variations observed in blazars. The detected microvariation had an amplitude of 0.061$\pm$0.005mag in the $V$ band and a blue color of $\Delta$($V-J$) $=$$-$0.025$\pm$0.011. Furthermore, we successfully detected an unprecedented, short time-scale polarimetric variation, which correlated with the brightness change. We revealed that the microvariation had a specific polarization component. The polarization degree of the variation component was higher than that of the total flux. These results suggest that the microvariability originated from a small and local region where the magnetic field was aligned.
AKARI/IRC Deep Survey in the North Ecliptic Pole Region
Authors: wada Takehiko , Matsuhara Hideo , Oyabu Shinki , Takagi Toshinobu , Lee Hyung Mok , Im Myungshin , Ohyama Youichi , Goto Tomotsugu , Pearson Chris P. , White Glenn J. , Serjeant Stephen , Wada Kensuke , Hanami Hitoshi 
Published: March 2014

Abstract
We have made a deep and wide imaging survey with all nine AKARI/IRC bands from 2 to 24$\mu$m within a half degree of the North Ecliptic Pole. The survey covered a circular area of 0.38deg$^2$ centered at RA $=$ 17h56m, Dec $=$ 66°37' where a deep optical multi-band survey has been conducted by Subaru/Suprime-Cam. The 5$\sigma$ sensitivity of the survey for point sources is 11.0, 48, 117, and 275$\mu$Jy at wavelengths 3, 7, 15, and 24$\mu$m, respectively. The survey is limited by sky noise at wavelengths from 7 to 24$\mu$m, and limited by source confusion from 2 to 4$\mu$m. We have also made a point source catalog at each band, consisting of more than 5000 sources with a 50% completeness limit of 93$\mu$Jy at 15$\mu$m. Our results are consistent with the pilot survey at faint fluxes and has better statistical significance at the bright fluxes. This is the first near- and mid-infrared sub-mJy extragalactic survey with contiguous wavelength coverage from 2 to 24$\mu$m and a large band-merged catalogue. It will provide powerful and unique diagnostics of obscured star-formation and AGN activities in the galaxies up to $z=2$.
Potassium Abundances in Red Giants of Mildly to Very Metal-Poor Globular Clusters
Authors: Takeda Yoichi , Kaneko Hiroyuki , Matsumoto Naoko , Oshino Shoichi , Ito Hiroko , Shibuya Takatoshi 
Published: March 2014

Abstract
A non-LTE analysis of KI resonance lines at 7664.91 and 7698.97 $Å$ was carried out for 15 red giants belonging to three globular clusters of different metallicity (M 4, M 13, and M 15) along with two reference early-K giants ($\rho$ Boo and $\alpha$ Boo), in order to check whether the K abundances are uniform within a cluster, and to investigate the behavior of the [K$/$Fe] ratio at the relevant metallicity range of $-$2.5 $\lesssim$ [Fe$/$H] $\lesssim$$-$1. We confirmed that [K$/$H] (as well as [Fe$/$H]) is almost homogeneous within each cluster to a precision of $\lesssim$ 0.1 dex, though dubiously large deviations are exceptionally seen for two peculiar stars showing signs of considerably increased turbulence in the upper atmosphere. The resulting [K$/$Fe] ratios are mildly supersolar by a few tenths of dex for three clusters, tending to gradually increase from $\sim$ 0.1–0.2 at [Fe$/$H] $\sim$$-$1 to $\sim+$0.3 at [Fe$/$H] $\sim$$-$2.5. This result connects reasonably well with the [K$/$Fe] trend of disk stars ($-$1 $\lesssim$ [Fe$/$H]) and that of extremely metal-poor stars ($-$4 $\lesssim$ [Fe$/$H] $\lesssim$$-$2.5). That is, [K$/$Fe] appears to continue a gradual increase from [Fe$/$H] $\sim$ 0 toward a lower metallicity regime down to [Fe$/$H] $\sim$$-$3, where a broad maximum of [K$/$Fe] $\sim$$+$0.3$-$0.4 is attained, possibly followed by a slight downturn at [Fe$/$H] $\lesssim$$-$3.
High-Resolution Near-Infrared Images of the T Tauri Binary System XZ Tauri
Authors: Hioki Tomonori , Itoh Yoichi , Oasa Yumiko , Fukagawa Misato , Kudo Tomoyuki , Mayama Satoshi , Pyo Tae-Soo , Hayashi Masahiko , Hayashi Saeko S. , Ishii Miki , Tamura Motohide 
Published: March 2014

Abstract
We present a high-resolution ($\sim $0$.\prime\prime$1 $=$ 14 AU) $H$-band image of XZ Tau, a 0$.\prime\prime$ 3-separated classical T Tauri binary system, taken with the Coronagraphic Imager with Adaptive Optics (CIAO) on the Subaru Telescope. We found a scattered light nebula extending to $\sim $2$.\prime\prime$4 from the secondary, XZ Tau S, in the northeast region of the binary. Its surface brightness is $\sim $16.2 mag arcsec$^{-2}$ in the $H$-band, and decreases as $r^{-1.6 \pm 0.1}$. Combined with the HST/ACS polarimetric images and the [Fe ii] $\lambda$1.644 $\micron$ spectra taken with the Infrared Camera and Spectrograph (IRCS) on the Subaru Telescope, the elongated structure is identified as a wall of a cavity blown by the previously known blueshifted outflow. By a comparison with previous measurements, we estimated that the orbital period is 1010$ \pm $260 yr and the total mass of the binary is 0.62$ \pm $0.36$ M_{\odot}$. The observed $H$-band magnitudes of both the primary and the secondary varied by as much as 1 mag over this decade. These $H$-band inconstancies may arise from a variable accretion rate and changing extinction toward each component.
CO J = 3–2 Emission from the “Water Fountain” Sources IRAS 16342-3814 and IRAS 18286-0959
Authors: Imai Hiroshi , He Jin-Hua , Nakashima Jun-ichi , Ukita Nobuharu , Deguchi Shuji , Koning Nico 
Published: March 2014

Abstract
We observed CO $J$$=$ 3–2 emission from “water-fountain” sources, which exhibit high-velocity collimated stellar jets traced by H$_{2}$O maser emission, with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope. We detected CO emission from two sources: IRAS 16342$-$3814 and IRAS 18286$-$0959. The IRAS 16342$-$3814 CO emission exhibits a spectrum that could be well fit to a Gaussian profile, rather than to a parabolic profile, with a velocity width (FWHM) of 158$ \pm $6 km s$^{-1}$ and an intensity peak at $V_{\rm LSR}$$=$ 50$ \pm $2 km s$^{-1}$. The mass-loss rate of the star is estimated to be $\sim $2.9 $\times$ 10$^{-5} M_{ \odot} $yr$^{-1}$. Our morpho-kinematic models suggest that the CO emission is optically thin, and associated with a bipolar outflow rather than with a (cold and relatively small) torus. The IRAS 18286$-$0959 CO emission has a velocity width (FWHM) of 3.0$ \pm $0.2 kms$^{-1}$, smaller than typically seen in AGB envelopes. The narrow velocity width of the CO emission suggests that it originates from either an interstellar molecular cloud or a slowly-rotating circumstellar envelope that harbors the H$_{2}$O maser source.
Suzaku Observations of SGR1900$+$14 and SGR1806$-$20
Authors: Nakagawa Yujin E. , Mihara Tatehiro , Yoshida Atsumasa , Yamaoka Kazutaka , Sugita Satoshi , Murakami Toshio , Yonetoku Daisuke , Suzuki Motoko , Nakajima Motoki , Tashiro Makoto S. , Nakazawa Kazuhiro 
Published: March 2014

Abstract
Spectral and timing studies of Suzaku ToO observations of two SGRs, 1900$+$14 and 1806$-$20, are presented. The X-ray quiescent emission spectra were well fitted by a two blackbody function, or a blackbody plus a power-law model. The non-thermal hard component discovered by INTEGRAL was detected by PIN diodes and its spectrum was reproduced by the power-law model reported by INTEGRAL. The XIS detected a periodicity of $P$$=$ 5.1998$\pm$0.0002 s for SGR1900$+$14 and $P$$=$ 7.6022$\pm$0.0007 s for SGR 1806$-$20. The pulsed fraction was related to the burst activity for SGR 1900$+$14.
Stars at the Tip of Peculiar Elephant Trunk-Like Clouds in IC 1848E: A Possible Third Mechanism of Triggered Star Formation
Authors: Chauhan Neelam , Ogura Katsuo , Pandey Anil K. , Samal Manash R. , Bhatt Bhuwan C. 
Published: March 2014

Abstract
The H II region IC 1848 harbors a lot of intricate elephant trunk-like structures that look morphologically different from usual bright-rimmed clouds (BRCs). Of particular interest is a concentration of thin and long elephant trunk-like structures in the southeastern part of IC 1848E. Some of them have an apparently associated star or two stars at their very tip. We conducted $VI_{\rm c}$ photometry of several of these stars. Their positions on the $V/(V$$-$$I_{\rm c}$) color–magnitude diagram as well as the physical parameters obtained by SED fittings indicate that they are low-mass pre–main-sequence stars having ages of mostly one Myr, or less. This strongly suggests that they formed from elongated, elephant trunk-like clouds. We presume that such elephant trunk-like structures are genetically different from BRCs, on the basis of the differences in morphology, size distributions, and the ages of the associated young stars. We suspect that those clouds have been caused by hydrodynamical instability of the ionization/shock front of the expanding H II region. Similar structures often show up in recent numerical simulations of the evolution of H II regions. We further hypothesize that this mechanism makes a third mode of triggered star formation associated with H II regions, in addition to the two known mechanisms, i.e., collect-and-collapse of the shell accumulated around an expanding H II region and radiation-driven implosion of BRCs originated from pre-existing cloud clumps.
Global Structure of Optically Thin, Magnetically Supported, Two-Temperature, Black Hole Accretion Disks
Authors: Oda Hiroshi , Machida Mami , Nakamura Kenji E. , Matsumoto Ryoji , Narayan Ramesh 
Published: March 2014

Abstract
We present global solutions of optically thin, two-temperature black hole accretion disks incorporating magnetic fields. We assume that the $\varpi \varphi$-component of the Maxwell stress is proportional to the total pressure, and prescribe the radial dependence of the magnetic flux advection rate in order to complete the set of basic equations. We obtained magnetically supported (low-$\beta $) disk solutions, whose luminosity exceeds the maximum luminosity for an advection-dominated accretion flow (ADAF), $L$$\gtrsim$ 0.4${\alpha}^2\ L_{\rm Edd}$, where $L_{\rm Edd}$ is the Eddington luminosity. The accretion flow is composed of the outer ADAF, a luminous hot accretion flow (LHAF) inside the transition layer from the outer ADAF to the low-$\beta $ disk, the low-$\beta $ disk, and the inner ADAF. The low-$\beta $ disk region becomes wider as the mass-accretion rate increases further. In the low-$\beta $ disk, the magnetic heating balances the radiative cooling, and the electron temperature decreases from $\sim\ $10$^{9.5}\ $K to $\sim\ $10$^{8}\ $K as the luminosity increases. These results are consistent with the anti-correlation between the energy cutoff in X-ray spectra (hence the electron temperature) and the luminosity when $L$$\gtrsim$ 0.1$L_{\rm Edd}$, observed in the bright/hard state during the bright hard-to-soft transitions of transient outbursts in galactic black hole candidates.
A Multidimensional Radiation Magnetohydrodynamics Code Based on Flux-Limited Diffusion and HLLD
Authors: Yang Xiaohong , Yuan Feng 
Published: March 2014

Abstract
We present a multidimensional radiation magnetohydrodynamics (MHD) code based on the high-resolution shock capturing schemes (HRSC), the flux-limited diffusion (FLD) approximation, and the assumption of local thermodynamic equilibrium (LTE). The HRSC, employing a conservative algorithm that accurately ensures conservation of the total energy of MHD is implemented using a third-order Runge-Kutte scheme and the HLLD Riemann solver. In the FLD approximation, because the evolution equations of the radiation energy flux are neglected, this code is easily implemented, though the FLD approximation is less accurate when dealing with highly anisotropic radiation fields in an optically thin region. We carried out classical tests for the MHD and for the subcritical and supercritical radiating shocks. The results show that this code can achieve the necessary accuracy and efficiency to solve the radiation-dominated astrophysical processes with the FLD approximation.
X-Ray Observations of the Supernova Remnant W 28 with Suzaku. I. Spectral Study of the Recombining Plasma
Authors: Sawada Makoto , Koyama Katsuji 
Published: March 2014

Abstract
We present Suzaku results of the mixed-morphology supernova remnant W 28. The X-ray spectra of the central region of W 28 exhibit many bright emission lines from highly ionized atoms. An optically thin thermal plasma in collisional ionization equilibrium, either of single temperature or multi temperatures, failed to reproduce the data with line-like and bump-like residuals at the Si-Ly$ \alpha$ energy and at 2.4–5.0 keV, respectively. The bumps probably correspond to radiative recombination continua from He-like Si and S. A simple recombining plasma model nicely fit the bump structures, but failed to fit low-energy bands. The overall spectra can be fit with a multi–ionization-temperature plasma with a common electron temperature. The multi-ionization temperatures are interpreted as elemental differences of ionization and recombination timescales. These results prefer the rarefaction scenario for the origin of the recombining plasma.