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Search Results: 1 - 10 of 2077 matches for " Hironori Matsumoto "
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Nature of the Unidentified TeV Source HESS J1614-518, Revealed by Suzaku and XMM-Newton Observations
Michito Sakai,Yukie Yajima,Hironori Matsumoto
Physics , 2011, DOI: 10.1093/pasj/63.sp3.S879
Abstract: We report on new Suzaku and XMM-Newton results concerning HESS J1614-518, which is one of the brightest extended TeV gamma-ray sources and has two regions with intense gamma-ray emission. We newly observed the south and center regions of HESS J1614-518 with Suzaku, since the north region, including the position of the 1st brightest peak of the TeV gamma-ray emission, has already been observed. No X-ray counterpart was found at the position of the 2nd brightest peak of the TeV gamma-ray emission; we estimated the upper limit of the X-ray flux to be 1.6 \times 10^{-13} erg cm^{-2} s^{-1} in the 2-10 keV band. The soft X-ray source Suzaku J1614-5152, which was found at the edge of the field of view in a previous observation, was also detected at the middle of HESS J1614-518. Analyzing the XMM-Newton archival data, we revealed that Suzaku J1614-5152 consists of multiple point sources. The X-ray spectrum of the brightest point source, XMMU J161406.0-515225, can be described by a power-law model with a photon index of Gamma = 5.2^{+0.6}_{-0.5}, or a blackbody model with temperature kT = 0.38^{+0.04}_{-0.04} keV. In the blackbody model, the hydrogen-equivalent column density is almost the same as that of the hard extended X-ray emission, Suzaku J1614-5141, which was found at the 1st peak position. If true, XMMU J161406.0-515225 may be physically related to Suzaku J1614-5141 and HESS J1614-518.
X-ray emission from a merger remnant, NGC 7252,the "Atoms-for-Peace" galaxy
Hisamitsu Awaki,Hironori Matsumoto,Hiroshi Tomida
Physics , 2001, DOI: 10.1086/338694
Abstract: We observed a nearby merger remnant NGC 7252 with the X-ray satellite ASCA, and detected X-ray emission with the X-ray flux of (1.8+/-0.3)E-13 ergs/s/cm/cm in the 0.5 - 10 keV band. This corresponds to the X-ray luminosity of 8.1E40 ergs/s. The X-ray emission is well described with a two-component model: a soft component with kT =0.72+/-0.13 keV and a hard component with kT > 5.1 keV. Although NGC 7252 is referred to as a dynamically young protoelliptical, the 0.5 - 4 keV luminosity of the soft component is about 2E40 ergs/s, which is low for an early-type galaxy. The ratio of L_X/L_FIR suggests that the soft component originated from the hot gas due to star formation. Its low luminosity can be explained by the gas ejection from the galaxy as galaxy winds. Our observation reveals the existence of hard X-ray emission with the 2 - 10 keV luminosity of 5.6E40 ergs/s. This may indicate the existence of nuclear activity or intermediate-mass black hole in NGC 7252.
Peculiar Chemical Abundances in the Starburst Galaxy M82 and Hypernova Nucleosynthesis
Hideyuki Umeda,Ken'ichi Nomoto,Takeshi Go Tsuru,Hironori Matsumoto
Physics , 2002, DOI: 10.1086/342650
Abstract: X-ray observations have shown that the chemical abundance in the starburst galaxy M82 is quite rich in Si and S compared with oxygen. Such an abundance pattern cannot be explained with any combination of conventional Type I and II supernova yields. Also the energy to heavy element mass ratio of the observed hot plasma is much higher than the value resulted from normal supernovae. We calculate explosive nucleosynthesis in core-collapse hypernovae and show that the abundance pattern and the large ratio between the energy and the heavy element mass can be explained with the hypernova nucleosynthesis. Such hypernova explosions are expected to occur for stars more massive than >~ 20-25 Msun, and likely dominating the starburst, because the age after the starburst in M82 is estimated to be as short as ~ 10^6 - 10^7 yr. We also investigate pair-instability supernovae (~ 150-300 Msun) and conclude that the energy to heavy element mass ratio in these supernovae is too small to explain the observation.
Discovery of Diffuse Hard X-Ray Emission from the Vicinity of PSR J1648-4611 with Suzaku
Michito Sakai,Hironori Matsumoto,Yoshito Haba,Yasufumi Kanou,Youhei Miyamoto
Physics , 2013, DOI: 10.1093/pasj/65.3.64
Abstract: We observed the pulsar PSR J1648-4611 with Suzaku. Two X-ray sources, Suzaku J1648-4610 (Src A) and Suzaku J1648-4615 (Src B), were found in the field of view. Src A is coincident with the pulsar PSR J1648-4611, which was also detected by the Fermi Gamma-ray Space Telescope. A hard-band image indicates that Src A is spatially extended. We found point sources in the vicinity of Src A by using a Chandra image of the same region, but the point sources have soft X-ray emission and cannot explain the hard X-ray emission of Src A. The hard-band spectrum of Src A can be reproduced by a power-law model with a photon index of 2.0^{+0.9}_{-0.7}. The X-ray flux in the 2-10 keV band is 1.4 \times 10^{-13} erg cm^{-2} s^{-1}. The diffuse emission suggests a pulsar wind nebula around PSR J1648-4611, but the luminosity of Src A is much larger than that expected from the spin-down luminosity of the pulsar. Parts of the very-high-energy gamma-ray emission of HESS J1646-458 may be powered by this pulsar wind nebula driven by PSR J1648-4611. Src B has soft emission, and its X-ray spectrum can be described by a power-law model with a photon index of 3.0^{+1.4}_{-0.8}. The X-ray flux in the 0.4-10 keV band is 6.4 \times 10^{-14} erg s^{-1} cm^{-2}. No counterpart for Src B is found in literatures.
Ratiometric Optical Temperature Sensor Using Two Fluorescent Dyes Dissolved in an Ionic Liquid Encapsulated by Parylene Film
Tetsuo Kan,Hironori Aoki,Nguyen Binh-Khiem,Kiyoshi Matsumoto,Isao Shimoyama
Sensors , 2013, DOI: 10.3390/s130404138
Abstract: A temperature sensor that uses temperature-sensitive fluorescent dyes is developed. The droplet sensor has a diameter of 40 μm and uses 1 g/L of Rhodamine B (RhB) and 0.5 g/L of Rhodamine 110 (Rh110), which are fluorescent dyes that are dissolved in an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate) to function as temperature indicators. This ionic liquid is encapsulated using vacuum Parylene film deposition (which is known as the Parylene-on-liquid-deposition (PoLD) method). The droplet is sealed by the chemically stable and impermeable Parylene film, which prevents the dye from interacting with the molecules in the solution and keeps the volume and concentration of the fluorescent material fixed. The two fluorescent dyes enable the temperature to be measured ratiometrically such that the droplet sensor can be used in various applications, such as the wireless temperature measurement of microregions. The sensor can measure the temperature of such microregions with an accuracy of 1.9 °C, a precision of 3.7 °C, and a fluorescence intensity change sensitivity of 1.0%/K. The sensor can measure temperatures at different sensor depths in water, ranging from 0 to 850 μm. The droplet sensor is fabricated using microelectromechanical system (MEMS) technology and is highly applicable to lab-on-a-chip devices.
A New Supernova Remnant Candidate and an Associated Outflow in the Sagittarius C Region
Takeshi Go Tsuru,Masayoshi Nobukawa,Hiroshi Nakajima,Hironori Matsumoto,Katsuji Koyama,Shigeo Yamauchi
Physics , 2009,
Abstract: We present the Suzaku results on a new candidate of a supernova remnant (SNR) in the Sagittarius C region. We detected diffuse X-rays of an elliptical shape (G359.41-0.12) and a chimney-like structure (the Chimney), both of which were fitted with a thin thermal the model of kBT ~1 keV temperature. The absorption columns are same between these two structures, indicating that both are located at the same distance in the same line of sight. The narrow band image and one-dimensional profile of S XV Kalpha at 2.45 keV show that the Chimney is emanating from G359.41-0.12. Therefore, these two sources are physically connected with each other. The sum of the thermal energies of the Chimney and G359.41-0.12 is estimated to be 1.4x10^50 erg, typical for a galactic SNR. G359.41-0.12 is likely to be a new SNR candidate and the Chimney is an associated outflow.
No X-Ray Excess from the HESS J1741-302 Region except a New Intermediate Polar Candidate
Hideki Uchiyama,Katsuji Koyama,Hironori Matsumoto,Omar Tibolla,Sarah Kaufmann,Stefan Wagner
Physics , 2011, DOI: 10.1093/pasj/63.sp3.S865
Abstract: With the Suzaku satellite, we observed an unidentified TeV gamma-ray source HESS J1741$-$302 and its surroundings. No diffuse or point-like X-ray sources are detected from the bright southern emission peak of HESS J1741$-$302. From its neighborhood, we found a new intermediate polar candidate at the position of $(\alpha, \delta)_{\rm J2000.0} = (\timeform{17h40m35.6s}, \timeform{-30D14m16s})$, which is designated as Suzaku J174035.6$-$301416. The spectrum of Suzaku J174035.6$-$301416 exhibits emission lines at the energy of 6.4, 6.7 and 7.0 keV, which can be assigned as the K$\alpha$ lines from neutral, He-like and H-like iron, respectively. A coherent pulsation is found at a period of 432.1 $\pm$ 0.1 s. The pulse profile is quasi-sinusoidal in the hard X-ray band (4$-$8 keV), but is more complicated in the soft X-ray band (1$-$3 keV). The moderate period of pulsation, the energy flux, and the presence of the iron K$\alpha$ lines indicate that Suzaku J174035.6$-$301416 is likely an intermediate polar, a subclass of magnetized white dwarf binaries (cataclysmic variables). Based on these discoveries, we give some implications on the origin of GCDX and brief comments on HESS J1741$-$302 and PSR B1737$-$30.
First Detection of A Sub-kpc Scale Molecular Outflow in the Starburst Galaxy NGC 3628
An-Li Tsai,Satoki Matsushita,Albert K. H. Kong,Hironori Matsumoto,Kotaro Kohno
Physics , 2012, DOI: 10.1088/0004-637X/752/1/38
Abstract: We successfully detected a molecular outflow with a scale of 370-450 pc in the central region of the starburst galaxy NGC 3628 through deep CO(1-0) observations by using the Nobeyama Millimeter Array (NMA). The mass of the outflowing molecular gas is ~2.8x10^7 M_sun, and the outflow velocity is ~90(+/-10) km s^{-1}. The expansion timescale of the outflow is 3.3-6.8 Myr, and the molecular gas mass flow rate is 4.1-8.5 M_sun yr^{-1}. It requires mechanical energy of (1.8-2.8)x10^{54} erg to create this sub-kpc scale molecular outflow. In order to understand the evolution of the molecular outflow, we compare the physical properties between the molecular outflow observed from our NMA CO(1-0) data and the plasma gas from the soft X-ray emission of the Chandra X-ray Observatory (CXO) archival data. We found that the distribution between the molecular outflow and the strong plasma outflow seems to be in a similar region. In this region, the ram pressure and the thermal pressure of the plasma outflow are 10^{-(8-10)} dyne cm^{-2}, and the thermal pressure of molecular outflow is 10^{-(11-13)} dyne cm^{-2}. This implies the molecular outflow is still expanding outward. The molecular gas consumption timescale is estimated as 17-27 Myr, and the total starburst timescale is 20-34 Myr. The evolutionary parameter is 0.11-0.25, suggesting that the starburst activity in NGC 3628 is still in a young stage.
Global Distribution of Fe K alpha Lines in the Galactic Center Region Observed with the Suzaku Satellite
Hideki Uchiyama,Masayoshi Nobukawa,Takeshi Go Tsuru,Katsuji Koyama,Hironori Matsumoto
Physics , 2011, DOI: 10.1093/pasj/63.sp3.S903
Abstract: We have surveyed spatial profiles of the Fe K$\alpha$ lines in the Galactic center diffuse X-rays (GCDX), including the transient region from the GCDX to the Galactic ridge X-ray emission (GRXE), with the Suzaku satellite. We resolved Fe K$\alpha$ line complex into three lines of Fe \emissiontype{I}, Fe \emissiontype{XXV} and Fe \emissiontype{XXVI} K$\alpha$, and obtained their spatial intensity profiles with the resolution of $\sim \timeform{0D.1}$. We compared the Fe \emissiontype{XXV} K$\alpha$ profile with a stellar mass distribution (SMD) model made from near infrared observations. The intensity profile of Fe \emissiontype{XXV} K$\alpha$ is nicely fitted with the SMD model in the GRXE region, while that in the GCDX region shows $3.8\pm0.3$ $(\timeform{0D.2}<|l|<\timeform{1D.5})$ or $19\pm6$ $(|l|<\timeform{0D.2})$ times excess over the best-fit SMD model in the GRXE region. Thus Fe \emissiontype{XXV} K$\alpha$ in the GCDX is hardly explained by the same origin of the GRXE. In the case of point source origin, a new population with the extremely strong Fe \emissiontype{XXV} K$\alpha$ line is required. An alternative possibility is that the majority of the GCDX is truly diffuse optically thin thermal plasma.
Gas, Iron and Gravitational Mass in Galaxy Clusters: The General Lack of Cluster Evolution at z < 1.0
Hironori Matsumoto,Takeshi Go Tsuru,Yasushi Fukazawa,Makoto Hattori,David S. Davis
Physics , 1999, DOI: 10.1093/pasj/52.1.153
Abstract: We have analyzed the ASCA data of 29 nearby clusters of galaxies systematically, and obtained temperatures, iron abundances, and X-ray luminosities of their intracluster medium (ICM). We also estimate ICM mass using the beta model, and then evaluate iron mass contained in the ICM and derive the total gravitating mass. This gives the largest and most homogeneous information about the ICM derived only by the ASCA data. We compare these values with those of distant clusters whose temperatures, abundances, and luminosities were also measured with ASCA, and find no clear evidence of evolution for the clusters at z<1.0. Only the most distant cluster at z=1.0, AXJ2019.3+1127, has anomalously high iron abundance, but its iron mass in the ICM may be among normal values for the other clusters, because the ICM mass may be smaller than the other clusters. This may suggest a hint of evolution of clusters at z ~ 1.0.
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