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Molecular Gas Feeding the Circumnuclear Disk of the Galactic Center
Hsieh, Pei-Ying,Koch, Patrick M.,Ho, Paul T. P.,Kim, Woong-Tae,Tang, Ya-Wen,Wang, Hsiang-Hsu,Yen, Hsi-Wei,Hwang, Chorng-Yuan American Astronomical Society 2017 The Astrophysical journal Vol.847 No.1
<P>The interaction between a supermassive black hole (SMBH) and the surrounding material is of primary importance in modern astrophysics. The detection of the molecular 2 pc circumnuclear disk (CND) immediately around the Milky Way SMBH, SgrA*, provides a unique opportunity to study SMBH accretion at subparsec scales. Our new wide-field CS(J = 2 - 1) map toward the Galactic center (GC) reveals multiple dense molecular streamers that originated from the ambient clouds 20 pc further out, and that are connected to the central 2 pc of the CND. These dense gas streamers appear to carry gas directly toward the nuclear region and might be captured by the central potential. Our phase-plot analysis indicates that these streamers show a signature of rotation and inward radial motion with progressively higher velocities as the gas approaches the CND and finally ends up corotating with the CND. Our results might suggest a possible mechanism of gas feeding the CND from 20 pc around 2 pc in the GC. In this paper, we discuss the morphology and the kinematics of these streamers. As the nearest observable Galactic nucleus, this feeding process may have implications for understanding the processes in extragalactic nuclei.</P>
Pei-Ying Lin,Gongchun He,Jyunde Chen,Atul Kumar Dwivedi,Shuchen Hsieh 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.82 No.-
We demonstrate an efficient plasmon catalytic activity of a newly constructed metal–molecular–semiconductor, SERS substrate Ag/PDA/CuO@GMF. The support of tubular GMF surface and strongadhesion of PDA layer provided a uniform and well-packed distribution of Ag NPs and CuO to derive anefficient surface plasmon catalytic activity of Ag/PDA/CuO@GMF for the conversion of 4-Nitrothiophenol(4-NTP) to 4,40-Dimercaptoazobenzene (4,40-DMAB). Significant surface-enhanced Raman scattering(SERS) signal of 4,40-DMAB and efficient catalytic activities of Ag/PDA/CuO@GMF were related to thecombined cofactors, (a) a long-range electromagnetic effect of Ag NPs and (b) a stimulated chargetransfer due to the presence of CuO and Ag NPs. In addition, charge redistributions among adsorbent 4,40-DMAB and metal segments (Ag and CuO) via PDA played an important role in obtaining enhanced surfaceplasmon induced catalytic activities. Moreover, we utilized the structural properties of the 3D microfiberto enhance the applicability of the substrate. It was further demonstrated that the substrate could be usedto adsorb and detect the gaseous pollutants in the environment, thus providing an effective method forrapid on-site analysis.
Girls’ and Boys’ Science Choices and Learning in Upper-Secondary Schools in Taiwan
Hsiao-chin Hsieh,Pei-ying Chen,Ta-sen Lin 숙명여자대학교 아시아여성연구원 2017 Asian Women Vol.33 No.3
This study explores differences in how high school girls and boys in upper-secondary schools in Taiwan choose courses and learn science. The Actor-Network Theory (ANT) is adopted as the analytical approach. Two upper-secondary schools, LL Senior High School and MM Vocational High School, were selected due to their emphasis on science and technology education. Student surveys were conducted to investigate how students chose between courses and majors; two chemistry lab classes, one led by a male teacher and the other by a female teacher, in LL Senior High School, and one chemical-engineering lab class of MM Vocational High School were observed multiple times. Lab class teachers from both schools were interviewed. The survey data showed clear gender segregation in both schools, but only part of the students considered gender to be an important factor influencing their selection of courses and major fields. Observations of the relatively gender-balanced chemistry laboratories revealed that equipment and instrumentation were sufficient and equally accessible to all, that girls and boys behaved differently in the lab, and that patterns of teacher-student interaction varied by teacher’s gender, which might result in differences in laboratory learning between boys and girls. The concept of embodied pedagogical insight of female teachers, which may specifically benefit girls’ learning, is discussed.
MILKY WAY SUPERMASSIVE BLACK HOLE: DYNAMICAL FEEDING FROM THE CIRCUMNUCLEAR ENVIRONMENT
Liu, Hauyu Baobab,Hsieh, Pei-Ying,Ho, Paul T. P.,Su, Yu-Nung,Wright, Melvyn,Sun, Ai-Lei,Minh, Young Chol IOP Publishing 2012 The Astrophysical journal Vol.756 No.2
<P>The supermassive black hole (SMBH), Sgr A*, at the Galactic center is surrounded by a molecular circumnuclear disk (CND) lying between 1.5 and 4 pc radii. The irregular and clumpy structures of the CND suggest dynamical evolution and episodic feeding of gas toward the central SMBH. New sensitive data from the Submillimeter Array and Green Bank Telescope reveal several >5-10 pc scale molecular arms, which either directly connect to the CND or may penetrate inside the CND. The CND appears to be the convergence of the innermost parts of large-scale gas streamers, which are responding to the central gravitational potential well. Rather than being a quasi-stationary structure, the CND may be dynamically evolving, incorporating inflow via streamers, and feeding gas toward the center.</P>
Minh, Young Chol,Liu, Hauyu Baobab,Ho, Paul T. P.,Hsieh, Pei-Ying,Su, Yu-Nung,Kim, Sungsoo S.,Wright, Melvyn IOP Publishing 2013 The Astrophysical journal Vol.773 No.1
<P>Ammonia (3, 3) and (6, 6) transitions have been observed using the Green Bank Telescope toward the Sgr A region. The gas is mainly concentrated in 50 km s(-1) and 20 km s(-1) clouds located in a plane inclined to the galactic plane. These 'main' clouds appear to be virialized and influenced by the expansion of the supernova remnant Sgr A East. The observed emission shows very complicated features in the morphology and velocity structure. Gaussian multi-component fittings of the observed spectra revealed that various 'streaming' gas components exist all over the observed region. These components include those previously known as 'streamers' and 'ridges,' but most of these components appear not to be directly connected to the major gas condensations (the 50 km s(-1) and 20 km s(-1) clouds). They are apparently located out of the galactic plane, and they may have a different origin than the major gas condensations. Some of the streaming components are expected to be sources that feed the circumnuclear disk of our Galactic center directly and episodically. They may also evolve differently than major gas condensations under the influence of the activities of the Galactic center.</P>
ASIAA EXTRAGALACTIC STUDY WITH THE SMA
MATSUSHITA SATOKI,MAO RUI-QING,MULLER SEBASTIEN,CHOU CHUEN- YI,SAWADA-SATOH SATOKO,TRUNG DINH-VAN,LIM JEREMY,HSIEH PEI-YING,PECK ALISON B. The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2
We present CO(3-2), CO(2-1), and 230 GHz (1.3 mm) continuum images of nearby galaxies taken with the Submillimeter Array (SMA). Our main topic is to study the relation between higher-J molecular gas (e.g., CO J=3-2, 2-1) and nuclear activities (e.g., active galactic nuclei [AGNs] and starbursts). The nearby Seyfert 2 galaxy M51 shows strong CO(3-2) emission from the circumnuclear molecular gas, with an intensity twice as strong as that of the CO(1-0) emission. Strong CO(3-2) emission enhancement suggests that the circum nuclear molecular gas in M51 is warm and dense, which may be related to the AGN activities. Molecular gas in the nearby moderate starburst galaxy NGC 6946 is distributed along the large-scale bar or spiral arms and along the minibar, and the multi-J CO line images show very similar distribution to each other. For this galaxy, there is no clear enhancement in higher-J lines as seen in M51, which may be because NGC 6946 does not have clear AGN activities. Based on the results of these two galaxies, the physical conditions of the circum nuclear molecular gas may be related to the AGN activities. We also observed the nearby edge-on starburst galaxy NGC 3628 and the starburst/Seyfert composite galaxy NGC 4945 with the CO(2-1) line and 230 GHz (1.3 mm) continuum emission. These information will give us some hints for understanding the relation between nuclear activities and circum nuclear molecular gas and dust.
INTERSTELLAR MEDIUM PROCESSING IN THE INNER 20 pc IN GALACTIC CENTER
Liu, Hauyu Baobab,Ho, Paul T. P.,Wright, Melvyn C. H.,Su, Yu-Nung,Hsieh, Pei-Ying,Sun, Ai-Lei,Kim, Sungsoo S.,Minh, Young Chol IOP Publishing 2013 The Astrophysical journal Vol.770 No.1
<P>We present the Submillimeter Array 157 pointing mosaic in 0.86 mm dust continuum emission with 5 ''.1 x 4 ''.2 angular resolution, and the National Radio Astronomy Observatory Green Bank 100 m Telescope (GBT) observations of the CS/(CS)-S-34/(CS)-C-13 1-0 and SiO 1-0 emission with <= 20 '' x 18 '' angular resolution. The dust continuum image marginally resolves at least several tens of 10-10(2) M-circle dot dense clumps in the 5' field including the circumnuclear disk (CND) and the exterior gas streamers. There is very good agreement between the high resolution dust continuum map of the CND and all previous molecular line observations. As the dust emission is the most reliable optically thin tracer of the mass, free from most chemical and excitation effects, we demonstrate the reality of the abundant localized structures within the CND, and their connection to external gas structures. From the spectral line data, the velocity dispersions of the dense clumps and their parent molecular clouds are similar to 10-20 times higher than their virial velocity dispersions. This supports the idea that the CND and its immediate environment may not be stationary or stable structures. Some of the dense gas clumps are associated with 22 GHz water masers and 36.2 GHz and 44.1 GHz CH3OH masers. However, we do not find clumps that are bound by the gravity of the enclosed molecular gas. Hence, the CH3OH or H2O maser emission may be due to strong (proto) stellar feedback, which may be dispersing some of the gas clumps.</P>