bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental Effect on the Subhalo Abundance—a Solution to the Missing Dwarf Problem
Authors: Ishiyama Tomoaki , Fukushige Toshiyuki , Makino Junichiro 
Published: March 2014

Abstract
Recent high-resolution simulations of the formation of dark-matter halos have shown that the distribution of subhalos is scale-free, in the sense that if scaled by the velocity dispersion of the parent halo, the subhalo velocity distribution functions of galaxy-sized and cluster-sized halos are identical. For cluster-sized halos, the simulation results agreed well with the observations. The simulations, however, predicted far too many subhalos for galaxy-sized halos. Our galaxy has several tens of known dwarf galaxies. On the other hand, simulated dark-matter halos contain thousands of subhalos. We performed a simulation of a single large volume, and measured the abundance of subhalos in all massive halos. We found that the variation of the subhalo abundance is very large, and those with the largest number of subhalos correspond to the simulated halos in previous studies. The subhalo abundance depends strongly on the local density of the background. Halos in high-density regions contain a large number of subhalos. Our Galaxy is in the low-density region. For our simulated halos in low-density regions, the number of subhalos is within a factor of four to that of our Galaxy. We argue that the “missing dwarf problem” is not a real problem, but is caused by biased selections of the initial conditions in previous studies, which were not appropriate for field galaxies.
H2O Maser Outflow from the Red Supergiant Star NML Cygni Observed with Japanese VLBI Network
Authors: Nagayama Takumi , Takeda Koji , Omodaka Toshihiro , Imai Hiroshi , Kameno Seiji , Sofue Yoshiaki , Doi Akihiro , Fujisawa Kenta , Habe Asao , Honma Mareki , Kawaguchi Noriyuki , Kawai Eiji , Kobayashi Hideyuki , Koyama Yasuhiro , Murata Yasuhiro , Sorai Kazuo , Sudou Hiroshi , Takaba Hiroshi , Tamura Sayaka , Wakamatsu Ken-Ichi 
Published: March 2014

Abstract
We present the proper motions of H$_2$O masers in NML Cygni, observed with the Japanese VLBI Network at three epochs spanning 455d. We detected about 15 maser features at each epoch. Overall, 13 features that were detected at least twice were tracked by their radial velocities and proper motions. The three-dimensional kinematics of the maser features indicate the presence of an expanding outflow. The major axis of the outflow is estimated to be at a position angle of $\sim\;$108°, and an inclination angle of $\sim\;$8° with respect to the line of sight. The H$_2$O masers are located between an apparent minimum radius of $\sim\;9.6 \times 10^{12}$m (64AU) and a maximum radius of $\sim\;3.0 \times 10^{13}$m (202AU), where the expansion velocity increases from 12 to 27kms$^{-1}$. A comparison with the distributions of SiO, H$_2$O, and OH masers suggests that the outflow of NML Cygni is expanding outside a radius of $\sim\;$1.5$\times$10$^{13}$m (100AU). This radius corresponds to 6 stellar radii, and is consistent with the radius of the inner boundary for the dust shell.
A Submillimeter Cartridge-Type Receiver: ALMA Band 8 (385--500 GHz) Qualification Model
Authors: Satou Naohisa , Sekimoto Yutaro , Iizuka Yoshizou , Ito Tetsuya , Shan Wen-Lei , Kamba Toshiaki , Kumagai Kazuyoshi , Kamikura Mamoru , Tomimura Yu , Serizawa Yasutaka , Asayama Shin'ichiro , Sugimoto Masahiro 
Published: March 2014

Abstract
We have developed a cartridge-type receiver covering the frequency band of 385-500 GHz as a qualification model of Atacama Large Millimeter/submillimeter Array (ALMA) band 8. It receives two orthogonal polarizations and down-converts the sideband-separated signals to intermediate frequencies (IF) of between 4 and 8 GHz. The cartridge-type receiver consists of cold optics, two feed horns, a wire grid, mirrors, two sideband-separating SIS mixers, cryogenic multipliers of a local oscillator (LO), cryogenic and warm IF amplifiers, a cartridge body, and sensors/wirings. These components were individually tested, and then the cartridge was integrated and tested as a complete assembly. We have also developed equipment for efficiency tests of both the components and the integrated receiver. The single sideband (SSB) noise temperature of this receiver is 100 K at the band center and 300 K at the band edges. The beam pattern and cross-polarization pattern are consistent with a physical optical calculation. The amplitude stability is around $3 \times 10^{-4}$ in 1 s. The phase stability is less than 2.0D on a time scale of 0.1 s to 10 min. These results are promising for a receiver in the ALMA.
Delay Time Distribution Measurement of Type Ia Supernovae by the Subaru/XMM-Newton Deep Survey and Implications for the Progenitor
Authors: Totani Tomonori , Morokuma Tomoki , Oda Takeshi , Doi Mamoru , Yasuda Naoki 
Published: March 2014

Abstract
The delay time distribution (DTD) of type Ia supernovae (SNe Ia) from star formation is an important clue to reveal the still unknown progenitor system of SNe Ia. Here, we report on a measurement of the SN Ia DTD in a delay time range of $t_{\rm Ia} = $ 0.1-8.0Gyr by using faint variable objects detected in the Subaru/XMM-Newton Deep Survey (SXDS) down to $i'$$\sim$ 25.5. We selected 65 SN candidates showing significant spatial offset from the nuclei of the host galaxies having an old stellar population at $z$$\sim$ 0.4-1.2, out of more than 1000 SXDS variable objects. Although spectroscopic type classification is not available for these, we quantitatively demonstrated that more than $\sim$80% of these should be SNe Ia. The DTD was derived using stellar age estimates of the old galaxies based on 9 band photometries from optical to mid-infrared wavelength. Combined with the observed SN Ia rate in elliptical galaxies at the local universe, the DTD in $t_{\rm Ia}$$\sim$ 0.1-10Gyr is well described by a featureless power-law as $f_{\rm D}$($t_{\rm Ia}$) $\propto$$t_{\rm Ia}^\alpha$ with $\alpha$$\sim$$-$1. The derived DTD is in excellent agreement with a generic prediction of the double-degenerate scenario, giving strong support to this scenario. In the single-degenerate (SD) scenario, although predictions by simple analytic formulations have broad DTD shapes that are similar to the observation, DTD shapes calculated by more detailed binary population synthesis tend to have strong peaks at characteristic time scales, which do not fit the observation. This result thus indicates either that the SD channel is not the major contributor to SNe Ia in an old stellar population, or that an improvement of binary population synthesis theory is required. Various sources of systematic uncertainties were examined and tested, but our main conclusions were not affected significantly.
Clustering of Meter-Wave Luminous Objects toward Monoceros
Authors: Deguchi Shuji , Koike Kazutaka 
Published: March 2014

Abstract
A distribution of the meter-wave luminous objects, which are bright at the frequency 74MHz (a wavelength of 4m), but not detectable at 1.4GHz (21cm) in VLA surveys, shows a notable concentration on a scale of a few degrees in the direction of Monoceros [($l$, $b$) $=$ (225$^{\circ}$, 4$^{\circ}$)]. We argue that it is a part of giant radio relics associated with a nearby cluster of galaxies with $c$z$\sim$ 2400kms$^{-1}$ centered on the spiral galaxy NGC 2377. The angular separation of these objects from the clustering center is consistent with the separation of distant relics from the cluster center if scaled by distance. This fact implies that the concentrations of meter-wave luminous objects can be used as a tracer of the structure of the Local Supercluster and its vicinity.
Measuring the Broad-Band X-Ray Spectrum from 400eV to 40keV in the Southwest Part of the Supernova Remnant RXJ1713.7$-$3946
Authors: Takahashi Tadayuki , Tanaka Takaaki , Uchiyama Yasunobu , Hiraga Junko S. , Nakazawa Kazuhiro , Watanabe Shin , Bamba Aya , Hughes John P. , Katagiri Hideaki , Kataoka Jun , Kokubun Motohide , Koyama Katsuji , Mori Koji , Petre Robert , Takahashi Hiromitsu , Tsuboi Yoko 
Published: March 2014

Abstract
We report on results from Suzaku broadband X-ray observations of the southwest part of the galactic supernova remnant (SNR) RXJ1713.7$-$3946 with an energy coverage of 0.4-40keV. The X-ray spectrum, presumably of synchrotron origin, is known to be completely lineless, making this SNR ideally suited for a detailed study of the X-ray spectral shape formed through efficient particle acceleration at high-speed shocks. With a sensitive hard X-ray measurement from the HXD PIN aboard Suzaku, we determined the hard X-ray spectrum in the 12-40keV range to be described by a power law with photon index of $\Gamma =$ 3.2$\pm$0.2, significantly steeper than the soft X-ray index of $\Gamma =$ 2.4$\pm$0.05 measured previously with ASCA and other missions. We find that a simple power law fails to describe the full spectral range of 0.4-40keV, and instead a power-law with an exponential cutoff with a hard index of $\Gamma =$ 1.50$\pm$0.09 and a high-energy cutoff of $\epsilon_{\rm c} =$ 1.2$\pm$0.3keV formally provides an excellent fit over the full bandpass. If we use the so-called SRCUT model, as an alternative model, it gives a best-fit rolloff energy of $\epsilon_{\rm roll}$$=$ 0.95$\pm$0.04keV. Together with the TeV $\gamma$-ray spectrum, ranging from 0.3 to 100TeV, recently obtained by HESS observations, our Suzaku observations of RXJ1713.7$-$3946 provide stringent constraints on the highest-energy particles accelerated in a supernova shock.
Suzaku Detection of Extended/Diffuse Hard X-Ray Emission from the Galactic Center
Authors: Yuasa Takayuki , Tamura Ken-ichi , Nakazawa Kazuhiro , Kokubun Motohide , Makishima Kazuo , Bamba Aya , Maeda Yoshitomo , Takahashi Tadayuki , Ebisawa Ken , Senda Atsushi , Hyodo Yoshiaki , Tsuru Takeshi Go , Koyama Katsuji , Yamauchi Shigeo , Takahashi Hiromitsu 
Published: March 2014

Abstract
Five on-plane regions within $\pm$0.8D of the galactic center were observed with the Hard X-ray Detector (HXD) and the X-ray Imaging Spectrometer (XIS) aboard Suzaku. From all regions, significant hard X-ray emission was detected with HXD-PIN up to 40keV, in addition to the extended plasma emission which is dominant in the XIS band. The hard X-ray signals are inferred to come primarily from a spatially extended source, rather than from a small number of bright discrete objects. Contributions to the HXD data from catalogued X-ray sources, typically brighter than 1mCrab, were estimated and removed using information from Suzaku and other satellites. Even after this removal, the hard X-ray signals remained significant, exhibiting a typical 12-40keV surface brightness of 4$\times$10$^{-10}$ergcm$^{-2}$s$^{-1}$deg$^{-2}$ and power-law-like spectra with a photon index of 1.8. Combined fittings to the XIS and HXD-PIN spectra confirm that a separate hard tail component is superposed onto the hot thermal emission, confirming a previous report based on the XIS data. Over the 5-40keV band, the hard tail is spectrally approximated by a power law of photon index $\sim$2, but better by those with somewhat convex shapes. Possible origins of the extended hard X-ray emission are discussed.
Spectral Study of the Galactic Ridge X-Ray Emission with Suzaku
Authors: Ebisawa Ken , Yamauchi Shigeo , Tanaka Yasuo , Koyama Katsuji , Ezoe Yuichiro , Bamba Aya , Kokubun Motohide , Hyodo Yoshiaki , Tsujimoto Masahiro , Takahashi Hiromitsu 
Published: March 2014

Abstract
In order to carry out a precise spectral study of the Galactic Ridge X-ray Emission using Suzaku, we have observed a typical Galactic plane field at $(l,b) =$ (28D46, $-$0D20), which is already deeply observed with Chandra, and known to be devoid of bright X-ray point sources. Thanks to the low background and high spectral resolution of Suzaku, we were able to resolve three narrow iron K-emission lines from low-ionized (6.41keV), helium-like (6.67keV), and hydrogenic ions (7.00keV). The cosmic-ray ion charge-exchange model or the non-equilibrium ionization plasma model are unlikely to explain these line features, since they require either broad emission lines or lines at intermediate ionization states. Collisional ionization equilibrium plasma is the likely origin for the 6.67keV and 7.00keV lines; however, the origin of the 6.41keV line, which is due to fluorescence from cold material, has not been elucidated. We could also precisely measure the absolute X-ray surface brightness in the direction of the Galactic plane. Excluding point sources brighter than $\sim$2 $\times 10^{-13}$ergs$^{-1}$cm$^{-2}$ (2-10keV), the total surface brightness on the Galactic plane is $\sim$6.1 $\times 10^{-11}$ergs$^{-1}$cm$^{-2}$deg$^{-2}$ (2-10keV), including the contribution of the cosmic X-ray background, which is estimated to be $\sim$1.3$\times 10^{-11}$ergs$^{-1}$cm$^{-2}$deg$^{-2}$.
Suzaku Wide-Band X-Ray Spectroscopy of the Seyfert2 AGN in NGC 4945
Authors: Itoh Takeshi , Done Chris , Makishima Kazuo , Madejski Grzegorz , Awaki Hisamitsu , Gandhi Poshak , Isobe Naoki , Dewangan Gulab C. , Griffthis Richard E. , Anabuki Naohisa , Okajima Takashi , Reeves James N. , Takahashi Tadayuki , Ueda Yoshihiro , Eguchi Satohi , Yaqoob Tahir 
Published: March 2014

Abstract
Suzaku observed a nearby Seyfert2 galaxy, NGC 4945, which hosts one of the brightest active galactic nuclei above 20keV. Combining data from the two detectors aboard Suzaku, the AGN intrinsic nuclear emission and its reprocessed signals were observed simultaneously. The intrinsic emission is highly obscured with an absorbing column of $\sim$5$\times 10^{24}$cm$^{-2}$. The spectrum below 10keV is dominated by a reflection continuum and emission lines from neutral/ionized material. Along with a neutral iron K$\alpha$ line, a neutral iron K$\beta$ line and a neutral nickel K$\alpha$ line were detected for the first time from this source. The neutral lines and the cold reflection continuum are consistent with both originating in the same location. The Compton down-scattered shoulder in the neutral Fe-K$\alpha$ line is $\sim 10\%$ in flux of the narrow core, which confirms that the line originates from reflection, rather than transmission. The flux of the intrinsic emission varied by a factor of $\sim 2$ within $\sim 20$ks, which requires the obscuring material to be geometrically thin. Broadband spectral modeling showed that the solid angle of the neutral reflector is less than a few $\times 10^{-2} \times 2\pi$. All of this evidence regarding the reprocessed signals suggests that a disk-like absorber/reflector is viewed from a near edge-on angle.
The Suzaku Observation of NGC3516: Complex Absorption and the Broad and Narrow FeK Lines
Authors: Markowitz Alex , Reeves James N. , Miniutti Giovanni , Serlemitsos Peter , Kunieda Hideyo , Yaqoob Tahir , Fabian Andrew C. , Fukazawa Yasushi , Mushotzky Richard , Okajima Takashi , Gallo Luigi C. , Awaki Hisamitsu , Griffiths Richard E. 
Published: March 2014

Abstract
We present results from a 150ks Suzaku observation of the Seyfert 1.5 NGC3516 in 2005 October. The source was in a relatively highly absorbed state. Our best-fit model is consistent with the presence of a low-ionization absorber having a column density near 5$\times$10$^{22}$cm$^{-2}$ and covering most of the X-ray continuum source (covering fraction 96-100%). A high-ionization absorbing component, which yields a narrow absorption feature consistent with FeXXVIK, is confirmed. A relativistically broadened FeK$\alpha$ line was required in all fits, even after the complex absorption was taken into account; an additional partial-covering component is an inadequate substitute for the continuum curvature associated with the broad Fe line. A narrow FeK$\alpha$ emission line has a velocity width consistent with the Broad Line Region. The low-ionization absorber may be responsible for producing the narrow FeK$\alpha$ line, though a contribution from additional material out of the line of sight is possible. We include in our model soft band emission lines from He- and H-like ions of N, O, Ne, and Mg, consistent with photo-ionization, though a small contribution from collisionally-ionized emission is possible.
Suzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-Ray Emission Profiles
Authors: Kazuyo Tokoi , Sato Kosuke , Ishisaki Yoshitaka , Ohashi Takaya , Yamasaki Noriko Y. , Nakazawa Kazuhiro , Matsushita Kyoko , Fukazawa Yasushi , Hoshino Akio , Tamura Takayuki , Egawa Chihiro , Kawano Naomi , Ota Naomi , Isobe Naoki , Kawaharada Madoka , Awaki Hisamitsu , Hughes John P. 
Published: March 2014

Abstract
The compact group of galaxies HCG 62 ($z=$ 0.0145) was observed for 120ks with Suzaku XIS and HXD-PIN. The XIS spectra for four annular regions were fitted with a two-temperature vapec model with variable abundance, combined with the foreground Galactic component. The Galactic component was described by a two-temperature apec model, and constrained to have a common surface brightness among the four annuli. We confirmed the multi-temperature nature of the intra-group medium, as reported previously, with a doughnut-like high temperature ring at radii 3.3'-6.5'. Abundances of Mg, Si, S, and Fe were well-constrained. We examined the possible “high-abundance arc” at $\sim 2'$ southwest from the center; however, Suzaku data did not confirm it. We suspect that it is a misidentification of an excess hot component in this region as the Fe line. Neither XIS (5-12keV) nor HXD-PIN (12-40keV) gave positive detection of the extended hard X-rays previously reported with ASCA, although our upper limit did not exclude the ASCA result. The 5-12keV intensity in the $r &lt;$ 3.3' region turned out to be 70$\pm$19% higher than the nominal CXB level, and Chandra and Suzaku data suggest a concentration of hard X-ray sources with an average photon index of $\Gamma=$ 1.38$\pm$0.06. The cumulative mass of O, Fe, and Mg in the intra-group medium and the metal mass-to-light ratio were compared with those in other groups. The possible role of AGN or galaxy mergers in this group is also discussed.
Suzaku Detection of an Intense X-Ray Flare from an A-Type Star, HD161084
Authors: Miura Junichiro , Tsujimoto Masahiro , Tsuboi Yohko , Maeda Yoshitomo , Sugawara Yasuharu , Koyama Katsuji , Yamauchi Shigeo 
Published: March 2014

Abstract
We report on a serendipitous detection of an intense X-ray flare from the Tycho reference source on HD161084 during a Suzaku observation of the galactic center region for $\sim$20ks. The X-ray Imaging Spectrometer recorded a flare from this A1-type dwarf or subgiant star with a flux of $\sim$1.4$\times$10$^{-12}$erg s$^{-1}$ cm$^{-2}$ (0.5-10keV) and a decay time scale of $\sim$0.5hr. The spectrum is hard with a prominent FeXXV K$\alpha$ emission line at 6.7keV, which is explained by a $\sim$5keV thin-thermal plasma model attenuated by a $\sim$1.4$\times$10$^{21}$cm$^{-2}$ extinction. The low extinction, which is consistent with the optical reddening, indicates that the source is a foreground star toward the galactic center region. Based on a spectroscopic parallax distance of $\sim$530pc, the peak X-ray luminosity amounts to $\sim$1$\times$10$^{32}$erg s$^{-1}$ (0.5-10keV). This is much larger than the X-ray luminosity of ordinary late-type main-sequence stars, and the X-ray emission is unattributable to a hidden late-type companion that comprises a wide binary system with the A star. We discuss possible nature of HD161084, and suggest that it is most likely an interacting binary with elevated magnetic activity in the companion, such as the Algol-type system. The flux detected by Suzaku during the burst is $\sim$100-times larger than the quiescent level measured using the archived XMM-Newton and Chandra data. The large flux amplification makes this star a unique example among sources of this class.
Suzaku Spectroscopy of Extended X-Ray Emission in M17
Authors: Hyodo Yoshiaki , Tsujimoto Masahiro , Hamaguchi Kenji , Koyama Katsuji , Kitamoto Shunji , Maeda Yoshitomo , Tsuboi Yohko , Ezoe Yuichiro 
Published: March 2014

Abstract
We present the results of a Suzaku spectroscopic study of soft extended X-ray emission in the HII region of M17. The spectrum of the extended emission was obtained with a high signal-to-noise ratio in a spatially resolved manner using the X-ray Imaging Spectrometer (XIS). We established that contamination by unresolved point sources, the Galactic Ridge X-ray emission, the cosmic X-ray background, and the local hot bubble emission is negligible in the background-subtracted XIS spectrum of the diffuse emission. Half a dozen emission lines were clearly resolved for the first time, including K$\alpha$ lines of highly ionized O, Ne, and Mg as well as L-series complex of Fe at 0.5-1.5keV. Based on diagnosis of these lines, we obtained the following results: (1) the extended emission is an optically thin thermal plasma, represented well by a single temperature of $\sim$3.0$\pm$0.4MK, (2) the abundances of elements with emission lines in the diffuse spectrum are 0.1-0.3 solar, while those of bright discrete sources are 0.3-1.5 solar, (3) the metal abundances relative to each other in the diffuse emission are consistent with solar, except for a Ne enhancement of a factor of $\sim$2, (4) both the plasma temperature and the chemical composition of the diffuse emission show no spatial variation across the studied spatial scale of $\sim$5pc.
Performance of an Imaging Fourier Transform Spectrometer with Photoconductive Detector Arrays: An Application for the AKARI Far-Infrared Instrument
Authors: Kawada Mitsunobu , Takahashi Hidenori , Murakami Noriko , Matsuo Hiroshi , Okada Yoko , Yasuda Akiko , Matsuura Shuji , Shirahata Mai , Doi Yasuo , Kaneda Hidehiro , Ootsubo Takafumi , Nakagawa Takao , Shibai Hiroshi 
Published: March 2014

Abstract
We have developed an imaging Fourier transform spectrometer (FTS) for space-based far-infrared astronomical observations. The FTS employs newly developed photoconductive detector arrays with a capacitive trans-impedance amplifier, which makes the FTS a completely unique instrument. The FTS was installed as a function of the far-infrared instrument (FIS: Far-Infrared Surveyor) aboard the Japanese astronomical satellite, AKARI, which was launched on 2006 February 21 (UT) from Uchinoura Space Center. The FIS-FTS had been operated for more than one year before liquid helium ran out on 2007 August 26. The FIS-FTS was operated nearly six hundreds times, which corresponds to more than one hundred hours of astronomical observations and almost the same amount of time for calibrations. As expected from laboratory measurements, the FIS-FTS performed well and has produced a large set of astronomical data for valuable objects. Meanwhile, it has become clear that the detector transient effect is a considerable factor for FTSs with photoconductive detectors. In this paper, the instrumentation of the FIS-FTS and interesting phenomena related to FTS using photoconductive detectors are described, and future applications of this kind of FTS system are discussed.