Yoshihiro Ueda

Optical Identification of the ASCA Large Sky Survey

We present results of optical identification of the X-ray sources detected in the ASCA Large Sky Survey. Optical spectroscopic observations were done for 34 X-ray sources which were detected with the SIS in the 2-7 keV band above 3.5 sigma. The sources are identified with 30 AGNs, 2 clusters of galaxies, and 1 galactic star. Only 1 source is still unidentified. The flux limit of the sample corresponds to 1 x 10^{-13} erg s^{-1} cm^{-2} in the 2-10 keV band. Based on the sample, the paper discusses optical and X-ray spectral properties of the AGNs, contribution of the sources to the Cosmic X-ray Background, and redshift and luminosity distributions of the AGNs. An interesting result is that the redshift distribution of the AGNs suggests a deficiency of high-redshift (0.510^{44} erg s^{-1}) absorbed narrow-line AGNs (so called type 2 QSOs).We present results of optical identification of the X-ray sources detected in the ASCA Large Sky Survey. Optical spectroscopic observations were done for 34 X-ray sources that were detected with the SIS in the 2-7 keV band above 3.5 ?. The flux limit corresponds to ~1 ? 10-13 ergs cm-2 s-1 in the 2-10 keV band. The sources are identified with 30 active galactic nuclei (AGNs), two clusters of galaxies, and one Galactic star. Only one source is still unidentified. All of the X-ray sources that have a hard X-ray spectrum with an apparent photon index of smaller than 1 in the 0.7-10 keV band are identified with narrow-line or weak-broad-line AGNs at redshifts smaller than 0.5. This fact supports the idea that absorbed X-ray spectra of narrow-line and weak-broad-line AGNs make the cosmic X-ray background (CXB) spectrum harder in the hard X-ray band than that of a broad-line AGN, which is the main contributor in the soft X-ray band. Assuming their intrinsic spectra are same as a broad-line AGN (a power-law model with a photon index of 1.7), their X-ray spectra are fitted with hydrogen column densities of log NH(cm-2) = 22-23 at the objects redshift. On the other hand, X-ray spectra of the other AGNs are consistent with that of a nearby type 1 Seyfert galaxy. In the sample, four high-redshift luminous broad-line AGNs show a hard X-ray spectrum with an apparent photon index of 1.3 ? 0.3. The hardness may be explained by the reflection component of a type 1 Seyfert galaxy. The hard X-ray spectra may also be explained by absorption with log NH(cm-2) = 22-23 at the objects redshift, if we assume an intrinsic photon index of 1.7. The origin of the hardness is not clear yet. Based on the log N- log S relations of each population, contributions to the CXB in the 2-10 keV band are estimated to be 9% for less-absorbed AGNs (log NH(cm-2) < 22) including the four high-redshift broad-line AGNs with a hard X-ray spectrum, 4% for absorbed AGNs (22 < log NH(cm-2) < 23, without the four hard broad-line AGNs), and 1% for clusters of galaxies in the flux range from 3 ? 10-11 ergs cm-2 s-1 to 2 ? 10-13 ergs cm-2 s-1. If the four hard broad-line AGNs are included in the absorbed AGNs, the contribution of the absorbed AGNs to the CXB is estimated to be 6%. In optical spectra, there is no high-redshift luminous cousin of a narrow-line AGN in our sample. The redshift distribution of the absorbed AGNs is limited below z = 0.5 excluding the four hard broad-line AGNs, in contrast to the existence of 15 less-absorbed AGNs above z = 0.5. The redshift distribution of the absorbed AGNs suggests a deficiency of AGNs with column densities of log NH(cm-2) = 22-23 in the redshift range 0.5-2, or in the X-ray luminosity range larger than 1044 ergs s-1, or both. If the large column densities of the four hard broad-line AGNs are real, they could complement the deficiency of X-ray absorbed luminous high-redshift AGNs.

A New Method for the Preparation of Non-Terminal Alkynes: Application to the Total Syntheses of Tulearin A and C

Lactones are known to react with the reagent generated in situ from CCl4 and PPh3 in a Wittig-type fashion to give gem-dichloro-olefin derivatives. Such compounds are now shown to undergo reductive alkylation on treatment with organolithium reagents RLi to furnish acetylene derivatives bearing the substituent R at their termini (R=Me, n-, sec-, tert-alkyl, silyl); the reaction can be catalyzed with either Cu(acac)2 or Fe(acac)3 /1,2-diaminobenzene. Two alkynol derivatives prepared in this way from readily accessible lactone precursors served as the key building blocks for the total syntheses of the cytotoxic marine macrolides tulearinu2005A (1) and C (2). The assembly of these fragile targets hinged upon ring closing alkyne metathesis (RCAM) followed by a formal trans-reduction of the resulting cycloalkynes via trans-hydrosilylation/protodesilylation.

Discovery of Repetitive Optical Variation Patterns from the Accretion Disk During the 2015 Outbursts of the Black Hole X-Ray Binary V404 Cyg

We report on multi-color optical photometry in the 2015 outbursts of V404 Cygni, an X-ray transient. This system showed optical oscillations on timescales of 100 sec to 2.5 hours in these outbursts, and they were correlated with the simultaneous X-ray variations. On the basis of the

Disco very of an extraordinary luminous and soft X-ray transient MAXI J0158744

sim

The ASCA Results of Gro J1744–28

1-min optical delays against X-rays and multi-wavelength SED analyses, the optical variability in this system was likely caused by X-ray reprocessing at the outer accretion disk. We also find that some repetitive optical oscillations can occur at mass accretion rates

Highly thickening starch adhesive composition and thickening method

>

広天域軟X線監視ミッションWF-MAXI WG 活動報告

10 times lower than previously thought. Although the mechanism of this kind of variations is still unclear, we suggest that the lack of sustained mass accretion, which would be induced in long-period systems, may be a key condition.

X線トランジェント天体MAXI J1807+132とMAXI J1535-571 の発見と追観測

Mikio Morii1, Hiroshi Tomida2, Masaki Kimura2, Fumitoshi Suwa3, Hitoshi Negoro3, Motoko Serino4, Jamie A. Kennea5, Kim L. Page6, Peter A. Curran7, Frederick M. Walter8, N. Paul. M. Kuin9, Tyler Pritchard5, Satoshi Nakahira2, Kazuo Hiroi10, Ryuichi Usui1, Nobuyuki Kawai1, Julian P. Osborne6, Tatehiro Mihara4, David N. Burrows5, Neil Gehrels11, Mitsuhiro Kohama2, Masaru Matsuoka4, Motoki Nakajima12, Peter W. A. Roming13, Kousuke Sugimori1, Mutsumi Sugizaki4, Yohko Tsuboi14, Hiroshi Tsunemi15, Yoshihiro Ueda10, Shiro Ueno2 and Atsumasa Yoshida16 1Department of Physics, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8551, Japan. 2ISS Science Project Office, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan. 3Department of Physics, Nihon University, 1-8-14 Surugadai, Chiyoda, Tokyo 101-8308, Japan. 4MAXI team, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. 5Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, Pennsylvania 16802, USA. 6Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK. 7International Centre for Radio Astronomy Research / Curtin University, GPO Box U1987, Perth, WA 6845, Australia. 8Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA. 9Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK. 10Department of Astronomy, Kyoto University, Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan. 11NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. 12School of Dentistry at Matsudo, Nihon University, 2-870-1 Sakaecho-nishi, Matsudo, Chiba 271-8587, Japan. 13Southwest Research Institute, Space Science and Engineering Division, PO Drawer 28510, San Antonio, Texas 78228-0510, USA. 14Department of Physics, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan. 15Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. 16Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan.

ASTRO-Hの目指すサイエンス II

We present the ASCA/GIS results of the transient source GRO J1744-28, the bursting X-ray pulsar, for the two times observations about one year apart. (the first and the second observations are on Feb. 27th 1996 and Mar. l6th 1997 respectively.) Since the discovery of GRO J1744-28 on Dec. 2 1995 with the BATSE observatory (Fishman et al. 1995; Kouveliotou et al.), thousands of Type II X-ray bursts, and sinusoidal pulsations have been observed in the X-ray band. No other source has ever been found to exhibit such unusual characteristics. Following each burst the flux decreases below, and recovers to the pre-burst persistent level (here after the dip) within a few seconds to a few minutes, depending on the total flux of the burst. We examined the spectrum of GRO J1744-28 during each persistent, dip, burst phases at the two observations. This is the first detail study of the spectra (l-10keV band) of GRO J1744-28.