Showing papers in "Publications of the Astronomical Society of Japan in 2011"

Asteroid Catalog Using AKARI: AKARI/IRC Mid-Infrared Asteroid Survey

Abstract: We present the results of an unbiased asteroid survey in the mid-infrared wavelength with the Infrared Camera (IRC) onboard the Japanese infrared satellite AKARI. About 20% of the point source events recorded in the AKARI All-Sky Survey observations are not used for the IRC Point Source Catalog (IRCPSC) in its production process because of the lack of multiple detection by position. Asteroids, which are moving objects on the celestial sphere, remain in these “residual events”. We identify asteroids out of the residual events by matching them with the positions of known asteroids. For the identified asteroids, we calculate the size and albedo based on the Standard Thermal Model. Finally we have a brand-new catalog of asteroids, named the Asteroid Catalog Using Akari (AcuA), which contains 5,120 objects, about twice as many as the IRAS asteroid catalog. The catalog objects comprise 4,953 main belt asteroids, 58 near Earth asteroids, and 109 Jovian Trojan asteroids. The catalog will be publicly available via the Internet.

Effect of Magnetic Braking on Circumstellar Disk Formation in a Strongly Magnetized Cloud

Abstract: Using resistive magnetohydrodynamics simulation, we consider circumstellar disk formation in a strongly magnetized cloud. As the initial state, an isolated cloud core embedded in a low-density interstellar medium with a uniform magnetic field was adopted. The cloud evolution was calculated until almost all gas inside the initial cloud fell onto either the circumstellar disk or a protostar, and a part of the gas was ejected into the interstellar medium by the protostellar outflow driven by the circumstellar disk. In the early main accretion phase, the disk size is limited to � 10 AU because the angular momentum of the circumstellar disk is effectively transferred by both magnetic braking and the protostellar outflow. In the later main accretion phase, however, the circumstellar disk grows rapidly and exceeds & 100 AU by the end of the main accretion phase. This rapid growth of the circumstellar disk is caused by depletion of the infalling envelope, while magnetic braking is effective when the infalling envelope is more massive than the circumstellar disk. The infalling envelope cannot brake the circumstellar disk when the latter is more massive than the former. In addition, the protostellar outflow weakens and disappears in the later main accretion phase, because the outflow is powered by gas accretion onto the circumstellar disk. Although the circumstellar disk formed in a magnetized cloud is considerably smaller than that in an unmagnetized cloud, a circumstellar disk exceeding 100 AU can form even in a strongly magnetized cloud.

Gas Slit Camera (GSC) onboard MAXI on ISS

Abstract: The Gas Slit Camera (GSC) is an X-ray instrument on the MAXI (Monitor of All-sky X-ray Image) mission on the International Space Station. It is designed to scan the entire sky every 92-minute orbital period in the 2‐30 keV band and to achieve the highest sensitivity among the X-ray all-sky monitors ever flown so far. The GSC employs large-area position-sensitive proportional counters with the total detector area of 5350 cm 2 . The on-board data processor has functions to format telemetry data as well as to control the high voltage of the proportional counters to protect them from the particle irradiation. The paper describes the instruments, on-board data processing, telemetry data formats, and performance specifications expected from the ground calibration tests.

Atlas and Catalog of Dark Clouds Based on the 2 Micron All Sky Survey

Abstract: This paper presents an atlas and catalog of dark clouds derived based on the 2 Micron All Sky Survey Point Source Catalog (2MASS PSC). Color excess maps of E(J H ) and E(H KS) as well as extinction maps of AJ , AH , and AKS covering all of the sky have been produced at the 1 0 grid with a changing angular resolution ( 10–120), depending on the regions in the sky. Maps drawn at the lower 150 grid with a fixed 1ı resolution were also derived for various sets of threshold magnitudes in the J , H , and KS bands to estimate the background star colors and star densities needed to derive the color excess and extinction maps. The maps obtained in this work are presented on various scales in a series of figures that can be used as an atlas of dark clouds for general research purposes. On the basis of the E(J H ) and AJ maps drawn at the 10 grid, we have carried out a systematic survey for dark clouds all over the sky. In total, we identified 7614 dark clouds, and measured the coordinates, extents, and AV values for each of them. We also searched for their counterparts in a previously published catalog of dark clouds based on the optical photographic plates DSS (Dobashi et al. 2005, PASJ, 57, S1). These cloud parameters, including the information of the counterparts, are compiled into a new catalog of dark clouds. The atlas and catalog organized in this paper mainly trace relatively dense regions in dark clouds, revealing a number of dense cloud cores leading to star formation, while those presented by Dobashi et al. based on the optical database are more suited to trace less-dense regions and to reveal the global extents of dark clouds. These two datasets are complementary, and all together, they are useful to picture the structures of dark clouds in various density ranges.

Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope. I. Correlations between Flux, Color, and Polarization

Abstract: We report on the correlation between the flux, color and polarization variations on time scales of days--months in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for >10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days--weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux--color correlation, the correlation of the flux and polarization degree was relatively weak; only 10 objects showed significant positive correlations. Rotations of polarization were detected only in three objects: PKS 1510-089, 3C 454.3, and PKS 1749+096, and possibly in S5 0716+714. We also investigated the dependence of the degree of variability on the luminosity and the synchrotron peak frequency, u_peak. As a result, we found that lower luminosity and higher u_peak objects had smaller variations in their amplitudes both in the flux, color, and polarization degree. Our observation suggests the presence of several distinct emitting sources, which have different variation time-scales, colors, and polarizations. We propose that the energy injection by, for example, internal shocks in relativistic shells is a major factor for blazar variations on time scales of both days and months.

In-Orbit Performance of MAXI Gas Slit Camera (GSC) on ISS

Abstract: We report the in-orbit performance of the Gas Slit Camera (GSC) on the MAXI (Monitor of All-sky X-ray Image) mission carried on the International Space Station (ISS). Its commissioning operation started on August 8, 2009, confirmed the basic performances of the effective area in the energy band of 2–30 keV, the spatial resolution of the slit-and-slat collimator and detector with 1.5 FWHM, the source visibility of 40-150 seconds for each scan cycle, and the sky coverage of 85% per 92-minute orbital period and 95% per day. The gas gains and read-out amplifier gains have been stable within 1%. The background rate is consistent with the past X-ray experiments operated at the similar low-earth orbit if its relation with the geomagnetic cutoff rigidity is extrapolated to the high latitude. We also present the status of the in-orbit operation and the calibration of the effective area and the energy response matrix using Crab-nebula data.

Astrometry of H$_{2}$ O Masers in Nearby Star-Forming Regions with VERA. IV. L 1448 C

Abstract: We have carried out multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of 22 GHz H2O 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 H2O maser in L 1448 C to be 4.31 0.33 milliarcseconds (mas), which corresponds to a distance of 232 18 pc from the Sun. The present result is in good agreement with that of another H2O 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.

Annual Parallax Measurements of an Infrared Dark Cloud, MSXDC G034.43+00.24 with VERA

Abstract: We have measured the annual parallax of the H2O maser source associated with an infrared dark cloud MSXDC G034.43+00.24 from the observations with VERA (VLBI Exploration of Radio Astrometry). The parallax is 0.643±0.049 mas, corresponding to the distance of 1.56 −0.11 kpc. This value is less than the half of the previous kinematic distance of 3.7 kpc. We revise the core mass estimates of MSXDC G034.43+00.24, based on virial masses, LTE masses and dust masses and show that the core masses decrease from the previous estimations of ∼ 1000M⊙ to hundreds of M⊙. The spectral type derived from the luminosity also changes from O9.5 to B1 in the case of MM1. This spectral type is still consistent with that of the massive star. The radial velocity derived from the flat rotation model is smaller than the observed velocity, which corresponds to the peculiar motion of ∼ 40 km s in the line-of-sight direction.

X-Ray Study of the Outer Region of Abell 2142 with Suzaku

Abstract: We observed outer regions of a bright cluster of galaxies, A 2142, with Suzaku. Temperature and brightness structures were measured out to the virial radius (r200) with good sensitivity. We confirmed a temperature drop from 9 keV around the cluster center to about 3.5 keV at r200, with the density profile well approximated by the ˇ-model with ˇ = 0.85. Within 0.4 r200, the entropy profile agrees with r, as predicted by the accretion shock model. The entropy slope becomes flatter in the outer region and negative around r200. These features suggest that the intracluster medium in the outer region is out of thermal equilibrium. Since the relaxation timescale of electron-ion Coulomb collisions is expected to be longer than the elapsed time after shock heating at r200, one plausible reason for the low entropy is a low electron temperature compared to that of ions. Other possible explanations would be gas clumpiness, turbulence and bulk motions of the ICM. We also searched for a warm-hot intergalactic medium around r200, and set an upper limit on the oxygen line intensity. Assuming a line-of-sight depth of 2 Mpc and oxygen abundance of 0.1 solar, the upper limit of an overdensity is calculated to be 280 or 380, depending on the foreground assumption.

Discovery of an excess of Hα emitters around 4C 23.56 at z = 2.48

Abstract: We report on the discovery of a significant excess of candidate H˛ emitters (HAEs) in the field of the radio galaxy 4C 2356 at z = 2483 Using the MOIRCS near-infrared imager on the Subaru Telescope we found 11 candidate emission-line galaxies to a flux limit of � 75 � 10 � 17 erg s � 1 cm � 2 , which is about 5-times excess from the expected field counts with an � 3-� significance Three of these have been spectroscopically confirmed as redshifted H˛ at z = 249 The distribution of candidate emitters on the sky is tightly confined to a 12-Mpc-radius area at z = 249, locating 4C 2356 at the western edge of the distribution An analysis of the deep Spitzer MIPS 24 � m imaging shows that there is also an excess of faint MIPS sources All but two of the 11 HAEs are also found in the MIPS data The inferred star-formation rate (SFR) of the HAEs based on the extinction-corrected H˛ luminosity (median �; — —

New Panoramic View of 12CO and 1.1 mm Continuum Emission in the Orion A Giant Molecular Cloud. I. Survey Overview and Possible External Triggers of Star Formation

Abstract: We present new, wide and deep images in the 1.1 mm continuum and the CO (J=1–0) emission toward the northern part of the Orion A Giant Molecular Cloud

X-Ray Spectrum of a Peculiar Supernova Remnant, G 359.1-0.5

Abstract: We present Suzaku results of a supernova remnant (SNR), G 359.1� 0.5, in the direction of the Galactic center region. From the SNR, we have found prominent K-shell lines of highly ionized Si and S ions, together with unusual structures at 2.5–3.0 and 3.1–3.6 keV. No canonical SNR plasma model, in either ionization equilibrium or under-ionization, can explain the structures. The energies and shapes of the structures are similar to those of the radiative transitions of free electrons to the K-shell of He-like Si and S ions (radiative recombination continuum: RRC). The presence of strong RRC structures indicates that the plasma is in over-ionization. In fact, the observed spectrum has been well-fitted with an over-ionized plasma model. The best-fit electron temperature of 0.29 keV is far smaller than the ionization temperature of 0.77 keV, which means that G 359.1� 0.5 is in an extreme condition of over-ionization. We report some cautions on the physical parameters, and comment about possible origins for the over-ionized plasma.

Measurements of Transit Timing Variations for WASP-5b

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 2 value is 32.2 with 9 degrees of freedom, which corresponds to a confidence level of 99.982% or 3.7 . 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 21m s , which corresponds to its mass of 22–70M 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 2M near 1:2 and 2:1 mean-motion resonances (MMRs) with WASP-5b at the 3 level, assuming that the two planets are co-planer. We also put an upper limit of 43M (3 ) 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.

X-Ray and Near-Infrared Observations of GX 339−4 in the Low/Hard State with Suzaku and IRSF

Abstract: X-ray and near-infrared (J –H–Ks) observations of the galactic black-hole binary GX 339 4 in the low/hard state were performed with Suzaku and IRSF in 2009 March. The spectrum in the 0.5–300 keV band is dominated by thermal Comptonization of multicolor disk photons, with a small contribution from a direct disk component, indicating that the inner disk is almost fully covered by hot corona with an electron temperature of 175 keV. The Comptonizing corona has at least two optical depths, 1, 0.4. Analysis of the iron-K line profile yields an inner-disk radius of (13.3 6:0)Rg (Rg represents the gravitational radius GM=c ), with the best-fit inclination angle of 50i. This radius is consistent with that estimated from the continuum fit by assuming the conservation of photon numbers in Comptonization. Our results suggest that the standard disk of GX 339 4 is likely truncated before reaching the innermost stable circular orbit (for a non-rotating black hole) in the low/hard states at 1% of the Eddington luminosity. The one-day averaged near-infrared light curves are found to be correlated with hard X-ray flux with FKs / F 0:45 X . The flatter near-infrared F spectrum than the radio one suggests that the optically thin synchrotron radiation from the compact jets dominates the near-infrared flux. Based on a simple analysis, we estimate the magnetic field and size of the jet base to be 5 10 G and 6 10 cm, respectively. The synchrotron self Compton component is estimated to be approximately 0.4% of the total X-ray flux.

A Possible Tilted Orbit of the Super-Neptune HAT-P-11b

Abstract: We report the detection of the Rossiter-McLaughlin effect for the eccentric, super-Neptune exoplanet HAT-P-11b, based on radial velocity measurements taken with HDS, mounted on the Subaru 8.2m telescope, and simultaneous photometry with the FTN 2.0m telescope, both located in Hawai’i. The observed radial velocities during a planetary transit of HAT-P-11b show a persistent blue-shift, suggesting a spinorbit misalignment in the system. The best-fit value for the projected spin-orbit misalignment angle is λ = 103 ◦ −19 . Our result supports the notion that eccentric exoplanetary systems are likely to have significant spin-orbit misalignment (e.g., HD 80606, WASP-8, WASP-14, WASP-17, and XO-3). This fact suggests that not only hot-Jupiters but also super-Neptunes like HAT-P-11b had once experienced dynamical processes such as planet-planet scattering or the Kozai migration.

Astrometry of Galactic Star-Forming Region ON2N with VERA: Estimation of the Galactic Constants

Abstract: We performed the astrometry of H2O masers in the Galactic star-forming region Onsala 2 North (ON 2 N) with the VLBI Exploration of Radio Astrometry (VERA). We obtained a trigonometric parallax of 0.261 ˙ 0.009 mas, corresponding to a heliocentric distance of 3.83 ˙ 0.13 kpc. ON 2 N is expected to be on the solar circle, because its radial velocity with respect to the local standard of rest (LSR) is nearly zero. By using the present parallax and proper motions of the masers, the galactocentric distance of the Sun and the Galactic rotation velocity at the Sun are found to be R0 = 7.80 ˙ 0.26 kpc and Θ0 = 213 ˙ 5k m s � 1 , respectively. The ratio of Galactic constants, namely the angular rotation velocity of the LSR, can be determined more precisely, and is found to be Ω0 =Θ 0=R0 = 27.3 ˙ 0.8 km s � 1 kpc � 1 , which is consistent with recent estimations, but different from 25.9 km s � 1 kpc � 1 derived from the recommended values of Θ0 and R0 by the International Astronomical Union (1985).

Sagittarius A Molecular Cloud Complex in H13CO+ and Thermal SiO Emission Lines

Abstract: Masato TSUBOI and Ken-ichi TADAKI Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Chuou-ku, Sagamihara 252-5210 Department of Astronomy, The University of Tokyo, 7-3-1 Bunkyo, Tokyo 113-0033 tsuboi@vsop.isas.jaxa.jp Atsushi MIYAZAKI Mizusawa VLBI Observatory, National Astronomical Observatory, Mizusawa, Oshu, Iwate 023-0861 and Toshihiro HANDA Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015

MOIRCS Deep Survey. IX. Deep Near-Infrared Imaging Data and Source Catalog

Abstract: We present deep J-, H-, and Ks-band imaging data of the MOIRCS Deep Survey (MODS), which was carried out with Multi-Object Infrared Camera and Spectrograph (MOIRCS) mounted on the Subaru telescope in the GOODS-North region. The data reach 5sigma total limiting magnitudes for point sources of J=23.9, H=22.8, and Ks=22.8 (Vega magnitude) over 103 arcmin^2 (wide field). In 28 arcmin^2 of the survey area, which is ultra deep field of the MODS (deep field), the data reach the 5sigma depths of J=24.8, H=23.4, and Ks=23.8. The spatial resolutions of the combined images are FWHM ~ 0.6 arcsec and ~ 0.5 arcsec for the wide and deep fields in all bands, respectively. Combining the MODS data with the multi-wavelength public data taken with the HST, Spitzer, and other ground-based telescopes in the GOODS field, we construct a multi-wavelength photometric catalog of Ks-selected sources. Using the catalog, we present Ks-band number counts and near-infrared color distribution of the detected objects, and demonstrate some selection techniques with the NIR colors for high redshift galaxies. These data and catalog are publicly available via internet.

Suzaku studies of wide-band spectral variability of the bright type i Seyfert galaxy Markarian 509

Abstract: The Type I Seyfert galaxy Markarian 509 was observed with Suzaku in 2010 November, for a gross time span of 2.2 days. Timing and spectral properties of the 0.5-45 keV X-rays, detected with the XIS and HXD, consistently revealed the presence of a soft spectral component that remained constant while the total X- ray intensity varied by \pm10%. This stable soft component, found in the 0.5-3.0 keV range, was interpreted as a result of thermal Comptonization in a corona with a temperature of ~ 0.5 keV and an optical depth of ~ 18. The time-avearged 0.5-45 keV Suzaku spectrum was reproduced successfully, as a combination of this thermal Comptonization component, a harder power-law of photon index ~ 1.8, moderate reflection, and an iron K-emission line. By analyzing four archival Suzaku datasets of the same object obtained in 2006, the thermal Comptonization component, which was stable during the 2.2 day pointing in 2010, was found to vary on time scales of a few weeks, independently of the power-law component. Implications of these results are discussed in terms of the "multi-zone Comptonization" view, obtained with Suzaku from the black hole binary Cygnus X-1.

Hydrodynamic interaction between the be star and the pulsar in the TeV binary PSR B1259-63/LS 2883

Abstract: We study the interaction between the Be star and the pulsar in the TeV binary PSR B1259−63/LS 2883, using 3-D SPH simulations of the tidal and wind interactions in this Be-pulsar system. We first run a simulation without pulsar wind nor Be wind, taking into account only the gravitational effect of the pulsar on the Be disk. In this simulation, the gas particles are ejected at a constant rate from the equatorial surface of the Be star, which is tilted in a direction consistent with multi-waveband observations. We run the simulation until the Be disk is fully developed and starts to repeat a regular tidal interaction with the pulsar. Then, we turn on the pulsar wind and the Be wind. We run two simulations with different wind mass-loss rates for the Be star, one for a B2V type and the other for a significantly earlier spectral type. Although the global shape of the interaction surface between the pulsar wind and the Be wind agrees with the analytical solution, the effect of the pulsar wind on the Be disk is profound. The pulsar wind strips off an outer part of the Be disk, truncating the disk at a radius significantly smaller than the pulsar orbit. Our results, therefore, rule out the idea that the pulsar passes through the Be disk around periastron, which has been assumed in the previous studies. It also turns out that the location of the contact discontinuity can be significantly different between phases when the pulsar wind directly hits the Be disk and those when the pulsar wind collides with the Be wind. It is thus important to adequately take into account the circumstellar environment of the Be star, in order to construct a satisfactory model for this prototypical TeV binary.

Discovery of a Cyclotron Resonance Feature in the X-Ray Spectrum of GX 304-1 with RXTE and Suzaku during Outbursts Detected by MAXI in 2010

Abstract: We report on the discovery of a cyclotron resonance scattering feature (CRSF) in the X-ray spectrum of GX 304� 1, obtained by RXTE and Suzaku during major outbursts detected by MAXI in 2010. The peak intensity in August reached 600 mCrab in the 2–20 keV band, which is the highest ever observed from this source. The RXTE observations on more than twenty occasions and one Suzaku observation revealed a spectral absorption feature at around 54 keV, which is the first CRSF detection from this source. The estimated strength of the surface magnetic field, 4.7 � 10 12 G, is one of the highest among binary X-ray pulsars from which CRSFs have ever been detected. The RXTE spectra taken during the August outburst also suggest that the CRSF energy changed over 50– 54 keV, possibly in a positive correlation with the X-ray flux. The behavior is qualitatively similar to that observed from Her X-1 on long time scales, or from A 0535+26, but different from the negative correlation observed from 4U 0115+63 and X 0331+53.

Cosmic Star-Formation Activity at z = 2.2 Probed by H α Emission-Line Galaxies

Abstract: We present a pilot narrow-band survey of H emitters at z = 2.2 in the Great Observatories Origins Deep Survey North (GOODS-N) field with MOIRCS instrument on the Subaru Telescope. The survey reached a 3 limiting magnitude of 23.6 (NB209), which corresponds to a 3 limiting line flux of 2.5 10 17 erg s 1 cm 2 over a 56 arcmin contiguous area (excluding a shallower area). From this survey, we have identified eleven H emitters and one AGN at z = 2.2 on the basis of narrow-band excesses and photometric redshifts. We obtained spectra for seven out of the new objects, including one AGN; also, an emission line above 3 was detected from all of them. We estimated star-formation rates (SFR) and stellar masses (Mstar) for individual galaxies. The average SFR and Mstar are 27.8Mˇ yr 1 and 4.0 10Mˇ, respectively. Their specific star-formation rates negatively correlate with their stellar masses. Fitting to a Schechter function yields the H luminosity function with logL = 42.82, log = 2.78, and = 1.37. The average star-formation rate density in the survey volume is estimated to be 0.31Mˇyr 1 Mpc 3 according to the Kennicutt relation between the H luminosity and the star-formation rate. We compared our H emitters at z = 2.2 in GOODS-N with narrow-band line emitters in other fields and clusters to see their time evolution and environmental dependence. We found that the star-formation activity is rapidly reduced from z = 2.5 to z = 0.8 in the cluster environment, while it only moderately changed in the field environment. This result suggests that the time scale of galaxy formation differs among different environments, and the star-forming activities in high density regions eventually overtake those in lower-density regions as a consequence of “galaxy-formation bias” at high redshifts.

Statistical Study on the Nature of Solar-Flux Emergence

Abstract: We studied 101 flux emergence events ranging from small ephemeral regions to large emerging flux regions that were observed with the Hinode Solar Optical Telescope filtergram. We investigated how the total magnetic flux of the emergence event controls the nature of emergence. To determine the modes of emergences, horizontal velocity fields of the global motion of the magnetic patches in the flux emerging sites were measured by local correlation tracking. Between two main polarities of the large emerging flux regions with more than around 2 � 10 19 Mx, there were converging flows of anti-polarity magnetic patches. On the other hand, small ephemeral regions showed no converging flow, but a simple diverging pattern. When we looked into the detailed features in the emerging sites, irrespective of the total flux and the spatial size, all of the emergence events were observed to consist of single or multiple elementary emergence unit(s). The typical size of unitary emergence is 4 Mm, and consistent with simulation results. From a statistical study of the flux emergence events, the maximum spatial distance between two main polarities, the magnetic flux growth rate and the mean separation speed were found to follow the power-law functions of the total magnetic flux with indices of 0.27, 0.57, and � 0.16, respectively. From a discussion on the observed power-law relations, we obtained a physical view of solar flux emergence, in which the emerging magnetic fields float and evolve while balancing to the surrounding turbulent atmosphere.

Astrometry of H2O Masers in the Massive Star-Forming Region IRAS 06061+2151 with VERA

Abstract: We measured the trigonometric annual parallax of an H2O maser source associated with the massive starforming region IRAS 06061+2151 with VERA The annual parallax of 0496 ˙ 0031 mas, corresponding to a distance of 202 +0:13 � 0:12 kpc, was obtained by 10 epochs of observations during the period from 2007 October to 2009 September This distance was obtained more accurately than the photometric one previously measured, and places IRAS 06061+2151 in the Perseus spiral arm We found that IRAS 06061+2151 also has a peculiar motion of larger than 15 km s � 1 which is counter to the Galactic rotation This is similar to the motions of five sources in the Perseus spiral arm, whose parallaxes and proper motions have already been measured with satisfactory accuracy Moreover, these sources move with an average of 27 km s � 1 toward the Galactic center and counter to the Galactic rotation

New Distance and Revised Natures of High-Mass Star Formation in G5.89–0.39

Abstract: We report on the astrometric observations of the 22 GHz H2O masers in the high mass star-forming region G5.89-0.39 with VERA (VLBI Exploration of Radio Astrometry). Newly derived distance of 1.28^{+0.09}_{-0.08} kpc is the most precise and significantly nearer than previous values. We revised physical parameters and reconsidered nature of G5.89-0.39 based on the new distance as follows. (1) The ionizing star of the ultra compact (UC) HII region is a late O-type (O8 - 8.5) zero age main sequence (ZAMS) star, consistent with previously established limits based on its infrared spectral line emission. (2) Crescent-like maser alignment at the position of the O type ZAMS star may trace accretion disk (or its remnant), which suggests that the star is still young and before complete evaporation of circumstellar materials. (3) Although the revised mass for the east-west outflow has been reduced, it still quite large (100 Msun) which indicates that a significant fraction of the mass is entrained material and that the dynamical age significantly underestimates the actual outflow age. Our newly-derived distance emphasizes that G5.89-0.39 is one of the nearest targets to investigate ongoing high-mass star formation and evolution in a compact cluster containing a young O-type star.

Infrared 3–4 μm Spectroscopy of Nearby PG QSOs and AGN–Nuclear Starburst Connections in High-Luminosity AGN Populations

Abstract: We present the results of infraredL-band (3–4 m) slit spectroscopy of 30 PG QSOs at z < 0.17, a representative sample of local high-luminosity, optically selected AGNs. The 3.3 m polycyclic aromatic hydrocarbon (PAH) emission feature is used to probe nuclear (< a few kpc) starburst activity and to investigate the connections between AGNs and nuclear starbursts in PG QSOs. The 3.3 m PAH emission is detected in the individual spectra of 5/30 of the observed PG QSOs. We constructed a composite spectrum of PAH-undetected PG QSOs and discerned the presence of the 3.3 m PAH emission therein. We estimated the nuclear-starburst and AGN luminosities from the observed 3.3 m PAH emission and 3.35 m continuum luminosities, respectively, and found that the nuclearstarburst-to-AGN luminosity ratios in PG QSOs are similar to those of previously studied AGN populations with lower luminosities, suggesting that AGN–nuclear starburst connections are valid over a wide luminosity range of AGNs in the local universe. The observed nuclear-starburst-to-AGN luminosity ratios in PG QSOs with available supermassive black-hole masses are comparable to a theoretical prediction based on the assumption that the growth of a supermassive black hole is controlled by starburst-induced turbulence.

Cross Spectral Calibration of Suzaku, XMM-Newton, and Chandra with PKS 2155-304 as an Activity of IACHEC

Abstract: We report on comparisons of the energy responses of the Suzaku XIS, the Chandra HRC and ACIS with the LETG, and the XMM-Newton MOS and pn using simultaneous data of the BL Lac object PKS 2155 304 taken in 2005, 2006, and 2008. From power-law fits to individual spectra, we have found that the photon index agrees among all instruments within ' 0.1, and that the resultant hydrogen column density values of the Chandra and XMM-Newton instruments differ from the value for PKS 2155 304 only by .1 10 cm , while that of Suzaku bears a larger systematic error of 4 10 cm , at most. We have carried out flux cross-calibration in seven small segments of energy bands between 0.5 keV and 10 keV. In the bands above 2 keV, the Suzaku fluxes are larger than those of XMM-Newton by ' 20%, ' 10%, and . 5% in 2005, 2006, and 2008, respectively, although the 20% difference in 2005 is still preliminary. The fluxes of the LETG+HRC in 2006 coincide with those of Suzaku below 2 keV. The fluxes of the LETG+ACIS are compared with those of Suzaku and XMM-Newton with the 2008 data, and are systematically larger than those of Suzaku and XMM-Newton by 10%. These results are in general consistent with those presented in one of the precedent papers from International Astronomical Consortium for High Energy Calibration (IACHEC) using G21.5 0.9.

Revisit of Local X-Ray Luminosity Function of Active Galactic Nuclei with the MAXI Extragalactic Survey

Abstract: We constructed a new X-ray (2–10 keV) luminosity function of Compton-thin active galactic nuclei (AGNs) in the local universe, using the first MAXI/GSC source catalog surveyed in the 4–10 keV band. The sample consists of 37 non-blazar AGNs at z = 0.002–0.2, whose identification is highly (>97%) complete. We confirmed the trend that the fraction of absorbed AGNs withNH > 10 cm 2 rapidly decreases against the luminosity (LX), from 0.73 0.10 at LX = 10 43:5 erg s 1 to 0.12 0.08 at LX = 1043:5–45:5 erg s . The obtained luminosity function was well-fitted with a smoothly connected double power-law model whose indices are 1 = 0.84 (fixed) and 2 = 2.0 0.2 below and above the break luminosity, L = 1043:3 0:4 erg s , respectively. While the result of the MAXI/GSC agrees well with that of HEAO-1 at LX & 10 erg s , it gives a larger number density at the lower luminosity range. A comparison between our luminosity function in the 2–10 keV band and that in the 14–195 keV band obtained from the Swift/BAT survey indicates that the averaged broad-band spectra in the 2–200 keV band should depend on the luminosity, approximated by Γ 1.7 for LX . 10 erg s , while Γ 2.0 for LX & 10 erg s . This trend was confirmed by the correlation between the luminosities in the 2–10 keV and 14–195 keV bands in our sample. We argue that there is no contradiction in the luminosity functions between above and below 10 keV once this effect is taken into account.