Search Publications
Suzaku discovery of Fe K-shell line from the O-rich SNR G292.0+1.8
Katsuda, Satoru; Koyama, Katsuji; Uchida, Hiroyuki +7 more
We report the Suzaku/XIS results of the Galactic oxygen-rich supernova remnant G292.0+1.8, a remnant of a core-collapse supernova. The X-ray spectrum of G292.0+1.8 consists of two types of plasma, one is in collisional ionization equilibrium (CIE) and the other is in non-equilibrium ionization (NEI). The CIE plasma has nearly solar abundances, and…
AKARI infrared camera observations of the 3.3 µm PAH feature in Swift/BAT AGNs
Nakagawa, Takao; Shirahata, Mai; Oyabu, Shinki +6 more
We explore the relationships between the 3.3 µm polycyclic aromatic hydrocarbon (PAH) feature and active galactic nucleus (AGN) properties of a sample of 54 hard X-ray selected bright AGNs, including both Seyfert 1 and Seyfert 2 type objects, using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI. The sample is se…
Observations of umbral dots and their physical models
Watanabe, Hiroko
The Hinode satellite opens a new era in sunspot research, because of its high spatial resolution and temporal stability. Fine-scale structures in sunspots, called umbral dots (UDs), have become one of the hottest topics in terms of close observations of magnetoconvection. In this paper, a brief review of the observed properties of UDs is given bas…
Point source calibration of the AKARI/FIS all-sky survey maps for stacking analysis
Doi, Yasuo; Takita, Satoshi; Arimatsu, Ko +5 more
Investigations of the point spread functions (PSFs) and flux calibrations for stacking analysis have been performed with the far-infrared (wavelength range of 60 to 140 µm) all-sky maps taken by the Far-Infrared Surveyor (FIS) on board the AKARI satellite. The PSFs are investigated by stacking the maps at the positions of standard stars with…
Broad-band spectroscopy of Hercules X-1 with Suzaku
Enoto, Teruaki; Yamada, Shin'ya; Tamagawa, Toru +4 more
Hercules X-1 was observed with Suzaku in the main-on state from 2005 to 2010. The 0.4-100 keV wide-band spectra obtained in four observations showed a broad hump around 4-9 keV in addition to narrow Fe lines at 6.4 and 6.7 keV. The hump was seen in all the four observations regardless of the selection of the continuum models. Thus it is considered…
Morphological study of penumbral formation
Kitai, Reizaburo; Watanabe, Hiroko; Otsuji, Ken'ichi
Penumbrae are known to be areas of mainly horizontal magnetic field surrounding umbrae of relatively large and mature sunspots. In this paper, we observationally studied the formation of penumbrae in NOAA 10978, where several penumbral formations were observed in G-band images of the Solar Optical Telescope on board Hinode. Thanks to the continuou…
Constraint on the gas-to-dust ratio in massive star-forming galaxies at z ∼ 1.4
Iono, Daisuke; Hatsukade, Bunyo; Ohta, Kouji +3 more
We carried out 12CO (J = 2-1) observations toward three star-forming galaxies on the main sequence at z ∼ 1.4 with the Nobeyama 45 m radio telescope. These galaxies have been detected with Spitzer/MIPS in 24 µm, Herschel/SPIRE in 250 µm and 350 µm; their gas metallicity, derived from optical emission line ratios based …
X-ray filament with a strong 6.7-keV line in the Galactic center region
Koyama, Katsuji; Nobukawa, Masayoshi; Nakashima, Shinya +3 more
An elongated X-ray source with a strong K-shell line from He-like iron (Fe XXVI) is found at (RA, Dec)J2000.0 = (17h44m00{s.}0, - 29°13'40{^''.}9) in the Galactic center region. The position coincides with the X-ray thread, G359.55+0.16, which is aligned with the radio non-thermal f…
X-ray emission from the galactic supernova remnant G12.0-0.1
Koyama, Katsuji; Bamba, Aya; Yamauchi, Shigeo
We present results of the Suzaku/XIS observation around the radio supernova remnant (SNR) G12.0-0.1. No significant diffuse emission extending in or along the radio shell was observed. Instead, two compact X-ray sources, Suzaku J181205-1835 and Suzaku J181210-1842, were found in or near G12.0-0.1. Suzaku J181205-1835 is located at the north-west o…
Discovery of an overlapping cluster in the Abell 1674 field with Suzaku
Koyama, Katsuji; Hayashida, Kiyoshi; Akamatsu, Hiroki +5 more
We present the results of a Suzaku observation of Abell 1674, an optically very rich (richness class 3) cluster cataloged as z = 0.1066. We discover the He-like Fe K-shell line from the central region for the first time, and find that the X-ray spectrum yields a high redshift of 0.215^{+0.007}_{-0.006}. On the other hand, the spectrum of the south…