Search Publications
Spatially Resolved Spectral Analysis of Vela Shrapnel D
Katsuda, Satoru; Tsunemi, Hiroshi
The ROSAT all-sky survey discovered several `shrapnels', showing boomerang structures outside the Vela supernova remnant. We observed shrapnel D with the XMM-Newton satellite. There is an X-ray bright ridge structure in our FOV running from north to south. Applying the VNEI model to X-ray spectra of various regions, we find that the plasma in the …
XMM-Newton Observation of IC 310 in the Outer Region of the Perseus Cluster of Galaxies
Ishida, Manabu; Sato, Kosuke; Ohashi, Takaya +3 more
We present results from an XMM-Newton observation of the head-tail radio galaxy IC 310 located in the southwest region of the Perseus cluster. The spectrum is well fitted by an absorbed power-law model with a photon index of 2.50 ± 0.02 without significant absorption excess. The X-ray image shows a point-like emission at IC 310 without any sign of…
Hα Stokes V/I Features Observed in a Solar Active Region
Hanaoka, Yoichiro
We carried out an imaging polarimetry observation of active region NOAA 10596 at 9-11 wavelengths around the Hα line with a ferroelectric liquid-crystal polarimeter during 2004 April 20-26. The latitude of the region was S8°, and it passed the central meridian on April 23. On the basis of this observation, the Stokes V/I features of the active reg…
Discovery of a Strongly Lensed Galaxy at z=3.9 behind a z=0.83 Galaxy Cluster
Kodama, Tadayuki; Tanaka, Ichi; Umetsu, Keiichi +4 more
We report on the discovery and spectroscopic confirmation of three gravitationally-lensed images of a galaxy at z=3.9 in the background of a distant, rich cluster of galaxies at z=0.83, on the basis of observations with Faint Object Camera And Spectrograph on the Subaru telescope. We construct a simple lens model of the cluster mass distribution b…
On I Line Emission in the Quasar PG 1116+215
Oyabu, Shinki; Matsuoka, Yoshiki; Yoshii, Yuzuru +2 more
By observing the near-infrared spectrum of the quasar PG 1116+215 at z = 0.176 and combining with the HST/FOS spectrum, we obtained the relative strengths of three permitted O I lines (λ1304, λ8446, and λ11287) in a quasar for the first time. The photon flux ratios of the O I lines of the quasar were compared with those previously measured in a Se…
Spectral Evolution of a Luminous Compact X-Ray Source in NGC 253 with Chandra and XMM-Newton Observatories
Makishima, Kazuo; Takahashi, Tadayuki; Kubota, Aya +2 more
Spectral studies of a luminous X-ray source, NGC 253 X21, are presented based on archival Chandra and XMM-Newton data. The Chandra observation on 1999 December 16 detected the source at a bolometric luminosity of 0.3 × 1039 erg s-1 (assuming isotropic emission), while an XMM-Newton observation on 2000 June 3 revealed a short-…
X-Ray Spectra of the Narrow-Line Seyfert 1 Galaxy Ton S180 in Comparison with Galactic Black Holes
Hong, Soojing; Kokubun, Motohide; Makishima, Kazuo +3 more
An analysis was made of 0.3-15keV X-ray spectra of a Narrow-Line Seyfert 1 Galaxy, Ton S180, using archival data from ASCA, RXTE, and XMM-Newton. At energies above 2.5keV, a power-law with a photon index of ∼ 2.3 successfully and consistently reproduced the spectra from all of these observatories. Assuming this power-law component to extend toward…
Partial Covering Interpretation of the X-Ray Spectrum of the NLS1 1H 0707-495
Ueda, Yoshihiro; Tanaka, Yasuo; Gallo, Luigi +2 more
The X-ray spectrum of 1H 0707 - 495 obtained with XMM-Newton showing a deep flux drop at ∼ 7 keV (Boller et al. 2002) is studied based on the partial covering concept. The previously inferred extreme iron overabundance can be reduced down to ∼ 3× solar if the hard component gradually steepens at high energies. The spectral shape supports that 1H 0…
Probing Warm-Hot Intergalactic Medium Associated with the Virgo Cluster Using an Oxygen Absorption Line
Kelley, Richard L.; Kilbourne, Caroline A.; Ohashi, Takaya +8 more
To detect a warm-hot intergalactic medium (WHIM) associated with the large-scale structure of the universe, we observed a quasar behind the Virgo cluster with XMM-Newton. With 54ks exposure, we marginally detected an O VIII Kα absorption line at 650.9+0.8-1.9eV in the RGS spectra, with a statistical confidence of 96.4%. The o…
Locating the Warm--Hot Intergalactic Medium in the Simulated Local Universe
Ishida, Manabu; Dolag, Klaus; Ohashi, Takaya +11 more
We present an analysis of mock spectral observations of warm-hot intergalactic medium (WHIM) using a constrained simulation of the local universe. The simulated map of oxygen emission lines from local WHIM well reproduces the observed structures traced by galaxies in the real local universe. We further attempt to perform mock observation of the ou…