Search Publications
Suzaku and NuSTAR X-ray spectroscopy of γ Cassiopeiae and HD 110432
Tsujimoto, Masahiro; Hayashi, Takayuki; Kitaguchi, Takao +1 more
γ Cas and its dozen analogs comprise a small but distinct class of X-ray sources. They are early Be-type stars with an exceptionally hard thermal X-ray emission. The X-ray production mechanism has been under intense debate. Two competing ideas are (i) the magnetic activities in the Be star and its disk, and (ii) the mass accretion onto the unident…
Hitomi observations of the LMC SNR N 132 D: Highly redshifted X-ray emission from iron ejecta
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +191 more
We present Hitomi observations of N 132 D, a young, X-ray bright, O-rich core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily detects the line complexes of highly ionized S K and Fe K with 16-17 counts in each. The Fe feature is measured for t…
Triggering the formation of the supergiant H II region NGC 604 in M 33
Tachihara, Kengo; Fukui, Yasuo; Sano, Hidetoshi +4 more
Formation mechanism of a supergiant H II region NGC 604 is discussed in terms of collision of H I clouds in M 33. An analysis of the archival H I data obtained with the Very Large Array (VLA) reveals complex velocity distributions around NGC 604. The H I clouds are composed of two velocity components separated by ∼20 km s-1 for an exten…
In-orbit performance of the soft X-ray imaging system aboard Hitomi (ASTRO-H)
Dotani, Tadayasu; Miller, Eric D.; Maeda, Yoshitomo +46 more
We describe the in-orbit performance of the soft X-ray imaging system consisting of the Soft X-ray Telescope and the Soft X-ray Imager aboard Hitomi. Verification and calibration of imaging and spectroscopic performance are carried out, making the best use of the limited data of less than three weeks. Basic performance, including a large field of …
In-flight calibration of Hitomi Soft X-ray Spectrometer. (3) Effective area
Maeda, Yoshitomo; Tsujimoto, Masahiro; Okajima, Takashi +14 more
We present the result of the in-flight calibration of the effective area of the Soft X-ray Spectrometer (SXS) on board the Hitomi X-ray satellite using an observation of the Crab nebula. We corrected for artifacts when observing high count rate sources with the X-ray microcalorimeter. We then constructed a spectrum in the 0.5-20 keV band, which we…
LAMOST J221750.59+210437.2: A new member of carbon-enhanced extremely metal-poor stars with excesses of Mg and Si
Honda, Satoshi; Li, Haining; Ishigaki, Miho N. +4 more
We report on the elemental abundances of the carbon-enhanced metal-poor (CEMP) star J2217+2104, discovered through our metal-poor star survey with LAMOST and Subaru. This object is a red giant and has extremely low Fe abundance ([Fe/H] = -4.0) and very large enhancement of C, N, and O with excesses of Na, Mg, Al, and Si. This star is a new example…
Hitomi X-ray observation of the pulsar wind nebula G21.5-0.9
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +194 more
We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5-0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant brea…
Search for thermal X-ray features from the Crab nebula with the Hitomi soft X-ray spectrometer
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +192 more
The Crab nebula originated from a core-collapse supernova (SN) explosion observed in 1054 AD. When viewed as a supernova remnant (SNR), it has an anomalously low observed ejecta mass and kinetic energy for an Fe-core-collapse SN. Intensive searches have been made for a massive shell that solves this discrepancy, but none has been detected. An alte…
Hitomi X-ray studies of giant radio pulses from the Crab pulsar
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +201 more
To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss o…
Discovery of recombining plasma from the faintest GeV supernova remnant HB 21 and a possible scenario for cosmic rays escaping from supernova remnant shocks
Nakazawa, Kazuhiro; Koyama, Katsuji; Bamba, Aya +4 more
We present an X-ray study of the GeV gamma-ray supernova remnant (SNR) HB 21 with Suzaku. HB 21 is interacting with molecular clouds, and is the faintest in the GeV band among known GeV SNRs. We discovered strong radiative recombination continua of Si and S from the center of the remnant, which provide direct evidence of a recombining plasma (RP).…