bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time-Resolved Spectral Variability of the Prompt Emission from GRB 070125 Observed with Suzaku/WAM
Authors: Onda Kaori , Tashiro Makoto S. , Nakagawa Yujin E. , Yamaoka Kazutaka , Terada Yukikatsu , Ohno Masanori , Sugita Satoshi , Sakamoto Takanori , Toma Kenji , Gandhi Poshak , Kodaka Natsuki , Iwakiri Wataru , Urata Yuji , Yamauchi Makoto , Fukazawa Yasushi 
Published: March 2014

Abstract
Time-resolved spectral analyses of GRB 070125 with significant photon detections over the MeV regime using Suzaku/WAM data are reported. The prompt emission interval was divided into 10 time regions, and their spectra were reproduced by a Band function or a cutoff power-law model. The spectra show a complex evolution; a soft-hard-soft trend is seen, rather than a typical hard-to-soft monotonic variation. In addition, a flat spectral slope in the low-energy band exceeding the slope expected from a simple synchrotron emission model is suggested in one of the time regions. These results imply that the internal shocks in the relativistic jet of GRB 070125 have different physical conditions. There is a possible excess at $\sim $ 2.2 MeV in the spectrum of 33 seconds after the trigger at a significant level of $\approx $98.5%, where the continuum spectrum is not reproduced by the Band function. These properties are only shown during the short prompt time interval of the prompt emission, and emphasize the utility of the Suzaku/WAM for the study of gamma-ray bursts.
Multiband Photopolarimetric Monitoring of an Outburst of the Blazar 3C 454.3 in 2007
Authors: Sasada Mahito , Uemura Makoto , Arai Akira , Fukazawa Yasushi , Kawabata Koji S. , Ohsugi Takashi , Yamashita Takuya , Isogai Mizuki , Nagae Osamu , Uehara Takeshi , Mizuno Tsunefumi , Katagiri Hideaki , Takahashi Hiromitsu , Sato Shuji , Kino Masaru 
Published: March 2014

Abstract
We report on optical—near-infrared photopolarimetric observations of a blazar 3C 454.3 over 200 d. The object experienced an optical outburst in 2007 July. This outburst was followed by a short state fainter than $V =$ 15.2 mag, lasting $\sim $25 d. The object then entered an active state during which we observed short flares having a timescale of 3–10 d. The object showed two types of features in the color–magnitude relationship. One was a “bluer-when-brighter” trend in the outburst state, and the other was a “redder-when-brighter” trend in the faint state. These two types of features suggest a contribution of thermal emission to the observed flux, as suspected in previous studies. Our polarimetric observation detected two episodes of rotation of the polarization vector. The first one was a counterclockwise rotation in the $QU$ plane during the outburst state. After this rotation event of the polarization vector, the object entered a rapidly fading stage. The second one was seen in a series of flares during the active state. Each flare had a specific position angle of polarization, which apparently rotated clockwise from the first to the last flares. Thus, the object exhibited rotations of the polarization vector in opposite directions. We estimated a decay timescale of the short flares during the active state, and then calculated an upper limit of the strength of the magnetic field, $B =$ 0.2 G, assuming a typical beaming factor of blazars, $\delta =$ 20. This upper limit of $B$ is smaller than those previously estimated from spectral analysis.
The Spectral Features of Disk and Corona with Mass Evaporation in the Low/Hard State
Authors: Qiao Erlin , Liu Bi Fang 
Published: March 2014

Abstract
We investigate the spectral features of accretion flows composed of an outer cool, optically thick disk and inner hot, optically thin, advection dominated accretion flows (ADAF) within the framework of disk and corona with mass evaporation (Liu et al. 2002a, ApJ, 575, 117). In this work, both the magnetic field and Compton scattering of soft photons from the disk by electrons in the corona are included to calculate the evaporation rates at different distances. The disk is truncated at the distance where the evaporation rate equals to the accretion rate [$\dot m_{\rm evap}$($r_{\rm tr}$) $= \dot m$]. For a series of accretion rates, the corresponding truncation radii are calculated out, with which we are able to calculate the emergent spectra from the inner ADAF $+$ outer disk $+$ corona. At very low accretion rates, the spectra are similar to that of a pure ADAF because the disk is truncated at large distances. The disk component becomes important at high accretion rates since the truncation occurs at small distances. An anti-correlation between the Eddington ratio, $\xi \equiv L_{0.5-25 \ {\rm keV}}/L_{\rm Edd}$, and the hard X-ray photon index, $\Gamma_{3-25 \ {\rm keV}}$, in low/hard states is predicted by the model. Comparing the theoretical results with observations, we find that our model can reproduce the anti-correlation between the Eddington ratio, $\xi$, and the hard X-ray photon index observed for the X-ray binary XTE J1118$+$480.
X-Ray Spectroscopy of Galactic Hot Gas along the PKS 2155$-$304 Sight Line
Authors: Hagihara Toshishige , Yao Yangsen , Yamasaki Noriko Y. , Mitsuda Kazuhisa , Wang Q. Daniel , Takei Yoh , Yoshino Tomotaka , McCammon Dan 
Published: March 2014

Abstract
We present a detailed spectroscopic study of the hot gas in the Galactic halo toward the direction of a blazer PKS 2155$-$304 ($z =$ 0.117). The O VII and O VIII absorption lines were measured with the Low and High Energy Transmission Grating Spectrographs aboard Chandra, and the O VII, O VIII, and Ne IX emission lines produced in an adjacent field of the PKS 2155$-$304 direction were observed with the X-ray Imaging Spectrometer aboard Suzaku. Assuming vertically exponential distributions of the gas temperature and the density, we performed a combined analysis of the absorption and emission data. The gas temperature and the density at the galactic plane were determined to be (2.5$^{+0.6}_{-0.3}$) $\times$ 10$^{6} $K and ($1.4^{+0.5}_{-0.4}$) $\times$ 10$^{-3} $cm$^{-3} $, and the scale heights of the gas temperature and density were 5.6$^{+7.4}_{-4.2}$ kpc and 2.3$^{+0.9}_{-0.8}$ kpc, respectively. These values are consistent with those obtained in the LMC X-3 direction.
Prospects for a Very High-Energy Blazar Survey by the Next-Generation Cherenkov Telescopes
Authors: Inoue Yoshiyuki , Totani Tomonori , Mori Masaki 
Published: March 2014

Abstract
The prospects for future blazar surveys by next-generation very high-energy (VHE) gamma-ray telescopes, such as Advanced Gamma-ray Imaging System (AGIS) and Cherenkov Telescope Array (CTA), are investigated using the latest model of blazar luminosity function and its evolution, which is in good agreement with the flux and redshift distribution of observed blazars as well as the extragalactic gamma-ray background. We extend and improve the template of spectral energy distributions (SEDs) based on the blazar SED sequence paradigm, to make it reliable also in the VHE bands (above 100 GeV) by comparing with the existing VHE blazar data. Assuming the planned CTA sensitivities, a blind survey using a total survey time of $\sim\ $100 hr could detect $\sim\ $3 VHE blazars, with larger expected numbers for wider/shallower surveys. We also discuss a following-up of Fermi blazars. The detectability of VHE blazars in the plane of the Fermi flux and redshift is presented, which would be useful for future survey planning. Prospects and strategies are discussed to constrain the extragalactic background light (EBL) by using the absorption feature of brightest blazar spectra, as well as cut-offs in the redshift distribution. We will be able to get useful constraints on EBL by VHE blazars at different redshifts ranging 0.3–1 TeV corresponding to $z =$ 0.10–0.36.
Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314
Authors: Sato Bun’ei , Omiya Masashi , Liu Yujuan , Harakawa Hiroki , Izumiura Hideyuki , Kambe Eiji , Toyota Eri , Murata Daisuke , Lee Byeong-Cheol , Masuda Seiji , Takeda Yoichi , Yoshida Michitoshi , Itoh Yoichi , Ando Hiroyasu , Kokubo Eiichiro , Ida Shigeru , Zhao Gang , Han Inwoo 
Published: March 2014

Abstract
We report on the detection of two substellar companions orbiting around evolved intermediate-mass stars by precise Doppler measurements at Subaru Telescope and Okayama Astrophysical Observatory. HD 145457 is a K0 giant with a mass of 1.9$\ M_{\odot}$, and has a planet of minimum mass, $m_2$ sin $i =$ 2.9$\ M_{\rm J}$, orbiting with a period of $P=176$ d and eccentricity of $e=0.11$. HD 180314 is also a K0 giant with 2.6$\ M_{\odot}$, and hosts a substellar companion of $m_2$ sin $i =$ 22$\ M_{\rm J}$, which falls in the brown-dwarf mass regime, in an orbit with $P =$ 396 d and $e =$ 0.26. HD 145457 b is one of the innermost planets and HD 180314 b is the seventh candidate of a brown-dwarf-mass companion found around evolved intermediate-mass stars.
Observations of Chromospheric Anemone Jets with Hinode Ca II Broadband Filtergraph and Hida Ca II Spectroheliograph
Authors: Morita Satoshi , Shibata Kazunari , UeNo Satoru , Ichimoto Kiyoshi , Kitai Reizaburo , Otsuji Ken-ichi 
Published: March 2014

Abstract
We report on the first simultaneous observations of chromospheric “anemone” jets in solar active regions with the Hinode Solar Optical Telescope (SOT) Ca II H broadband filtergraph and the Ca II K spetroheliograph on the Domeless Solar Telescope (DST) at Hida Observatory. During the period of coordinated observations, nine chromospheric anemone jets were simultaneously observed with the two instruments. These observations revealed three important features: (1) the jets are generated in the lower chromosphere; i.e., these cannot be seen in Ca II K$_{3}$; (2) the length and lifetime of the jets are 0.4–5 Mm and 40–320 s, respectively; (3) the apparent velocity of the jets observed with the SOT is 3–24 km s$^{-1}$, while the Ca II K$_{3}$ component at the jets shows a blueshift (in 5 events) in the range of 2–6 km s$^{-1}$. The chromospheric anemone jets are associated with mixed polarity regions, which are either small emerging flux regions or moving magnetic features. It is found that the Ca II K line often shows red or blue asymmetry in the K$_{2}$/K$_{1}$ component; the footpoint of the jets associated with emerging flux regions often shows a redshift (2–16 km s$^{-1}$), while the one with moving magnetic features shows a blueshift ($\sim\ $5 km s$^{-1}$). A detailed analysis of the magnetic evolution of the jet-forming regions revealed that the reconnection rate (or canceling rate) of the total magnetic flux at the footpoint of the jets is on the order of 10$^{16}\ $Mx s$^{-1}$, and the resulting magnetic energy release rate is (1.1–10) $\times$ 10$^{24}\ $erg s$^{-1}$, with a total energy release of (1–13) $\times$ 10$^{26}\ $erg for the duration of the magnetic cancellation, $\sim\ $130 s. These are comparable to the estimated total energy, $\sim\ $10$^{26}\ $erg, in a single chromospheric anemone jet. In addition to the DST Ca II K spectroheliogram and the SOT Ca II H broadband filtergram, we also used for analysis an SOT magnetogram as well as a Hida H$\alpha $ filtergram. We present a physical model of the jet based on the observation, and discuss the relation between chromospheric anemone jets and Ellerman bombs.
Modeling the Gamma-Ray Emission Produced by Runaway Cosmic Rays in the Environment of RX J1713.7$-$3946
Authors: Casanova Sabrina , Jones David I. , Aharonian Felix A. , Fukui Yasuo , Gabici Stefano , Kawamura Akiko , Onishi Toshikazu , Rowell Gavin , Sano Hidetoshi , Torii Kazufumi , Yamamoto Hiroaki 
Published: March 2014

Abstract
Diffusive shock acceleration in supernova remnants is the most widely invoked paradigm to explain the Galactic cosmic ray spectrum. Cosmic rays escaping from supernova remnants diffuse into the interstellar medium and collide with the ambient atomic and molecular gas. From such collisions gamma-rays are created, which can possibly provide the first evidence of a parent population of runaway cosmic rays. We present model predictions for the GeV to TeV gamma-ray emission produced by the collisions of runaway cosmic rays with the gas in the surroundings of the shell-type supernova remnant RX J1713.7$-$3946. The spectral and spatial distributions of the emission, which depend upon the source age, the source injection history, the diffusion regime, and the distribution of the ambient gas, as mapped by the LAB and NANTEN surveys, are studied in detail. For the surrounding region of RX J1713$-$3946 in particular, we find out that it depends on the energy band one is observing whether one may observe startlingly different spectra or may not detect any enhanced emission with respect to the diffuse emission contributed by background cosmic rays. This result has important implications for current and future gamma-ray experiments.
Evolution of the Kippenhahn–Schlüter Prominence Model Magnetic Field under Cowling Resistivity
Authors: Hillier Andrew , Shibata Kazunari , Isobe Hiroaki 
Published: March 2014

Abstract
We present the results from 1.5D diffusion simulations of the Kippenhahn–Schlüter prominence model magnetic field evolution under the influence of the ambipolar terms of Cowling resistivity. We show that initially the evolution is determined by the ratio of the horizontal and vertical magnetic fields, which gives current sheet thinning (thickening) when this ratio is small (large) and a marginal case where a new characteristic current sheet length scale is formed. After a timespan greater than the Cowling resistivity time, the current sheet thickens as a power law of $t$ independent of the ratio of the field strengths. These results imply that when Cowling resistivity is included in the model, the tearing instability time scale is reduced by more than one order of magnitude when the ratio of the horizontal field to the vertical field is 20% or less. These results imply that, over the course of its lifetime, the structure of the prominence can be significantly altered by Cowling resistivity, and in some cases will allow the tearing instability to occur.
Absolute Dimensions and Apsidal Motion of the Young Detached System LT Canis Majoris
Authors: Bakiş Volkan , Bulut İbrahim , Bilir Selçuk , Bakiş Hicran , Demircan Osman , Hensberge Herman 
Published: March 2014

Abstract
New high-resolution spectra of the short-period ($P \sim$ 1.76 days) young detached binary LT CMa are reported for the first time. By combining the results from an analysis of new radial-velocity curves and published light curves, we determine values for the masses, radii, and temperatures as follows: $M_{\rm 1} =$ 5.59 (0.20)$\ M_{\odot}, R_{\rm 1} =$ 3.56 (0.07)$\ R_{\odot}$, and $T_{\rm eff1} =$ 17000 (500) K for the primary and $M_{\rm 2} =$ 3.36 (0.14)$\ M_{\odot}, R_{\rm 2} =$ 2.04 (0.05)$\ R_{\odot}$, and $T_{\rm eff2} =$ 13140 (800) K for the secondary. Static absorbtion features apart from those coming from the close binary components were detected in the several spectral regions. If these absorbtion features are from a third star, as the light-curve solutions support, its radial velocity is measured to be $RV_{\rm 3} =$ 70 (8) km s$^{-1}$. The orbit of the binary system has been proved to be eccentric ($e =$ 0.059) and thus apsidal motion exists. The estimated linear advance in longitude of periastron corresponds to an apsidal motion of $U =$ 69$\ \pm\ $5 yr for the system. The average internal structure constant, log $k_{\rm 2,obs} = -$2.53 of LT CMa, is found to be smaller than its theoretical value of log $k_{\rm 2,theo} = -$2.22, suggesting that the stars would have a more central concentration in mass. The photometric distance of LT CMa ($d =$ 535$\ \pm\ $45 pc) is found to be much smaller than the distance of the CMa OB1 association (1150 pc), which rules out membership. A comparison with current stellar evolution models for solar metallicity indicates that LT CMa (35 Myr) is much older than the CMa OB1 association (3 Myr), confirming that LT CMa is not a member of CMa OB1. Kinematical and dynamical analyses indicate that LT CMa is orbiting the Galaxy in a circular orbit, and belongs to the young thin-disk population.
Suzaku Observations of the Supernova Remnant N23 in the Large Magellanic Cloud
Authors: Someya Kentaro , Bamba Aya , Ishida Manabu 
Published: March 2014

Abstract
X-ray emission from the supernova remnant N23 in the Large Magellanic Cloud (LMC) has been studied using the X-ray Imaging Spectrometer (XIS) onboard Suzaku. Thanks to a superior energy resolution of the XIS in the soft X-ray band, we resolved H-like and He-like Oxygen K$\alpha$ emission lines from N23 with unprecedentedly high quality, and as a result, identified a new optically thin thermal emission component with a temperature of $\sim\ $0.2 keV, as well as that with a temperature of $\sim\ $0.5–0.7 keV, previously known. This alters the estimate of the ionization timescale, $n_{\rm e}t$, from $\sim\ $10$^{10-11}\ $cm$^{-3}\ $s to $\gtrsim\ $10$^{12}\ $cm$^{-3}\ $s. Under the assumption that N23 is still in the Sedov phase, its age, evaluated from the newly discovered low-temperature component, is $\sim\ $8000 yr, although it is possible that N23 has already moved into the radiative phase. The abundances of the heavy elements are found to be roughly consistent with those of the LMC average, which indicates that the origin of the X-ray emission of N23 is swept-up ambient material, as expected from its ionization timescale.
Astrometry of H$_{2}$ O Masers in Nearby Star-Forming Regions with VERA. IV. L 1448 C
Authors: Hirota Tomoya , Honma Mareki , Imai Hiroshi , Sunada Kazuyoshi , Ueno Yuji , Kobayashi Hideyuki , Kawaguchi Noriyuki 
Published: March 2014

Abstract
We have carried out multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of 22 GHz H$_{2}$ O masers associated with a Class 0 protostar, L 1448 C, in the Perseus molecular cloud. The maser features trace the base of a collimated bipolar jet driven by one of the infrared counter parts of L 1448 C, named as L 1448 C(N) or L 1448-mm A. We detected possible evidence for apparent acceleration and precession of the jet according to the three-dimensional velocity structure. Based on phase-referencing VLBI astrometry, we successfully detected an annual parallax of the H$_{2}$ O maser in L 1448 C to be 4.31$\ \pm\ $ 0.33 milliarcseconds (mas), which corresponds to a distance of 232$\ \pm\ $ 18 pc from the Sun. The present result is in good agreement with that of another H$_{2}$ O maser source, NGC 1333 SVS 13, in the Perseus molecular cloud, 235 pc. It is also consistent with the photometric distance, 220 pc. Thus, the distance to the western part of the Perseus molecular cloud complex would be constrained to be about 235 pc, rather than a larger value, 300 pc, previously reported.
Measurements of Transit Timing Variations for WASP-5b
Authors: Fukui Akihiko , Narita Norio , Tristram Paul J. , Sumi Takahiro , Abe Fumio , Itow Yoshitaka , Sullivan Denis J. , Bond Ian A. , Hirano Teruyuki , Tamura Motohide , Bennett David P. , Furusawa Kei , Hayashi Fumiya , Hearnshaw John B. , Hosaka Shun , Kamiya Koki , Kobara Shuhei , Korpela Aarno , Kilmartin Pam M. , Lin Wei , Ling Cho Hong , Makita Shota , Masuda Kimiaki , Matsubara Yutaka , Miyake Noriyuki , Muraki Yasushi , Nagaya Maiko , Nishimoto Kenta , Ohnishi Kouji , Omori Kengo , Perrott Yvette , Rattenbury Nicholas , Saito Toshiharu , Skuljan Ljiljana , Suzuki Daisuke , Sweatman Winston L. , Wada Kohei 
Published: March 2014

Abstract
We observed 7 new transits of the “hot Jupiter” WASP-5b using a 61 cm telescope located in New Zealand, in order to search for transit timing variations (TTVs), which can be induced by additional bodies existing in the system. Combining them with other available photometric and radial velocity (RV) data, we find that its transit timings do not match a linear ephemeris; the best-fit $\chi^2$ value is 32.2 with 9 degrees of freedom, which corresponds to a confidence level of 99.982% or 3.7 $\sigma$. This result indicates that excess variations of transit timings have been observed, either due to unknown systematic effects, or possibly due to real TTVs. The TTV amplitude is as large as 50 s, and if this is real it cannot be explained by some effect other than an additional body, or bodies. From RV data, we put an upper limit on the RV amplitude caused by a possible secondary body (planet) as 21 m s$^{-1}$, which corresponds to its mass of 22–70$\ M_{\oplus}$ over the orbital period ratio of the two planets from 0.2 to 5.0. From the TTV data, using numerical simulations, we narrowed the limits down to 2$\ M_{\oplus}$ near 1:2 and 2:1 mean-motion resonances (MMRs) with WASP-5b at the 3$\sigma$ level, assuming that the two planets are co-planer. We also put an upper limit of 43$\ M_{\oplus}$ (3$\sigma$) on excess of Trojan mass using both RV and photometric data. We also find that if the orbit of the possible secondary planet is a circle or an ellipse of small eccentricity, it would be likely an orbit near that of low-order MMRs.
Physical Properties of the Transiting Planetary System TrES-3
Authors: Lee Jae Woo , Youn Jae-Hyuck , Kim Seung-Lee , Lee Chung-Uk , Koo Jae-Rim 
Published: March 2014

Abstract
We present four new transits of the planetary system TrES-3 observed between 2009 May and 2010 June. Among these, the third transit by itself indicates possible evidence for brightness disturbance, which might be a result of the planet blocking a cool starspot on the stellar surface. A total of 109 transit times, including our measurements, were used to determine the improved ephemeris with a transit epoch of 2454185.910944$\ \pm\ $0.000072 HJED and an orbital period of 1.30618700$\ \pm\ $0.00000015 d. We analyzed the transit light curves using the JKTEBOP code and adopting the quadratic limb-darkening law. In order to derive the physical properties of the TrES-3 system, the transit parameters were combined with the empirical relations from eclipsing binary stars and stellar evolutionary models. The stellar mass and radius obtained from a calibration using $T_{\rm A}$, log$\ \rho_{\rm A}$, and [Fe$/$H] are consistent with those from an isochrone analysis. We found that the exoplanet TrES-3b has a mass of 1.93$\ \pm\ $0.07$\ M_{\rm Jup}$, a radius of 1.30$\ \pm\ $0.04$\ R_{\rm Jup}$, a surface gravity of log$\ g_{\rm b}$$=$ 3.45$\ \pm\ $0.02, a density of 0.82$\ \pm\ $0.06 $\rho_{\rm Jup}$, and an equilibrium temperature of 1641$\ \pm\ $23 K. The results are in good agreement with theoretical models for gas giant planets.