Search Publications
Searches for H2O masers toward narrow-line Seyfert 1 galaxies
Hagiwara, Yoshiaki; Doi, Akihiro; Hachisuka, Kazuya +1 more
We present searches for 22 GHz H2O masers toward 36 narrow-line Seyfert 1 galaxies (NLS1s), selected from known NLS1s with vsys ≲ 41000 km s-1. Out of the 36 NLS1s in our sample, 11 have been first surveyed in our observations, while the observations of other NLS1s were previously reported in literature. In our sur…
Energy-dependent intensity variation of the persistent X-ray emission of magnetars observed with Suzaku
Enoto, Teruaki; Ebisawa, Ken; Nakagawa, Yujin
The emission mechanism of magnetars is still controversial even though various observational and theoretical studies have been made. In order to investigate mechanisms of both the persistent X-ray emission and the burst emission of the magnetars, we propose a model in which the persistent X-ray emission consists of numerous micro-bursts of various…
X-ray-bright optically faint active galactic nuclei in the Subaru Hyper Suprime-Cam wide survey
Greene, Jenny E.; Ueda, Yoshihiro; Terashima, Yuichi +8 more
We construct a sample of X-ray-bright optically faint active galactic nuclei by combining Subaru Hyper Suprime-Cam, XMM-Newton, and infrared source catalogs. Fifty-three X-ray sources satisfying i-band magnitude fainter than 23.5 mag and X-ray counts with the EPIC-PN detector larger than 70 are selected from 9.1 deg2, and their spectral…
Formation of the young massive cluster R136 triggered by tidally-driven colliding H i flows
Inoue, Tsuyoshi; Tachihara, Kengo; Fukui, Yasuo +4 more
Understanding massive cluster formation is one of the important issues of astronomy. By analyzing the H i data, we have identified that the two H i velocity components (L- and D-components) are colliding toward the H i Ridge, in the southeastern end of the Large Magellanic Cloud (LMC), which hosts the young massive cluster R136 and ∼400 O/Wolf-Ray…
Evolution of N/O abundance ratios and ionization parameters from z ∼ 0 to 2 investigated by the direct temperature method*†
Ono, Yoshiaki; Ouchi, Masami; Harikane, Yuichi +3 more
We present N/O abundance ratios, ionization parameters qion, and oxygen abundances O/H for a total of 41 galaxies (11 individual galaxies and a 30-galaxy stack) including Lyα emitters and Lyman break galaxies at z ∼ 2, and investigate galaxy evolution from z ∼ 0 to 2 in conjunction with 208529 local galaxies from the Sloan Digital Sky S…
Ultraviolet to optical diffuse sky emission as seen by the Hubble Space Telescope Faint Object Spectrograph
Oyabu, Shinki; Brandt, Timothy D.; Matsuoka, Yoshiki +5 more
We present an analysis of the blank-sky spectra observed with the Faint Object Spectrograph on board the Hubble Space Telescope. We study the diffuse sky emission from ultraviolet to optical wavelengths, which is composed of zodiacal light (ZL), diffuse Galactic light (DGL), and residual emission. The observations were performed towards 54 fields …
Lithium in CEMP-no stars: A new constraint on the lithium depletion mechanism in the early universe*
Li, Haining; Matsuno, Tadafumi; Aoki, Wako +1 more
Most relatively warm, unevolved, metal-poor stars (Teff ≳ 5800 K and [Fe/H] ≲ -1.5) exhibit almost constant lithium abundances, irrespective of metallicity or effective temperature, and thus form the so-called Spite plateau. This was originally interpreted as arising from lithium created by the Big Bang nucleosynthesis. Recent observati…
ALMA deep field in SSA22: Blindly detected CO emitters and [C II] emitter candidates
Smail, Ian; Fujimoto, Seiji; Inoue, Akio K. +21 more
We report the identification of four millimeter line-emitting galaxies with the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We analyze the ALMA 1.1-mm survey data, with an effective survey area of 5 arcmin2, frequency ranges of 253.1-256.8 and 269.1-272.8 GHz, angular resolution of 0{^''.}7 and rms …
Black hole spin of Cygnus X-1 determined from the softest state ever observed
Done, Chris; Fukazawa, Yasushi; Takahashi, Hiromitsu +3 more
We show the softest ever spectrum from Cyg X-1, detected in 2013 with Suzaku. This has the weakest high-energy Compton tail ever seen from this object, so should give the cleanest view of the underlying disk spectrum, and hence the best determination of black hole spin from disk continuum fitting. Using the standard model of a disk with simple non…
Suzaku observations of the outskirts of the galaxy cluster Abell 3395, including a filament toward Abell 3391
Ohashi, Takaya; Takizawa, Motokazu; Fujita, Yutaka +4 more
The results of Suzaku observations of the outskirts of Abell 3395, including a large-scale structure filament toward Abell 3391, are presented. We measured temperature and abundance distributions from the southern outskirt of A 3395 to the north at the virial radius, where a filament structure has been found in the former X-ray and Sunyaev-Zel'dov…