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Activity > Colloquium

Colloquium (2007)

ASIAA Colloquium is usually held on Wednesdays at 2:20-3:20 pm in Room 1203 of the Astronomy-Mathematics Building, NTU. All scientists are welcome to attend.

The ASIAA-NTU joint colloquium series aims to bring to the physics/astronomy/cosmology community in ASIAA/NTU world renown researchers who will talk about the forefront development of physical sciences.

Contact: Colloquium Committee (talks_replace2@_asiaa.sinica.edu.tw)

No. Time/Place Speaker Topic / Abstract
download PDF: download talk PDF file
12007-12-28 Fri
14:00~15:00
R716
Prof. Guey-Lin Lin
[National Chiao Tung University]
Neutrinos--Messengers in the Universe
22007-12-21 Fri
14:00~15:00
R716
Prof. Albert Kong
[NTHU]
X-tra Galactic Compact Binaries: A Multi-wavelength Approach
32007-12-07 Fri
12:00~13:00
R716
Prof. Paul Ricker
[UIUC]
Sources of scatter in galaxy cluster mass-observable relations
42007-11-30 Fri
14:00~15:00
R716
Prof. Bun'ei Sato
[Tokyo Institute of Technology]
Search for Planets around Giant Stars
Abstract

Doppler planet searches around G and K-type giant stars have expanded during these five years aiming to reveal properties of planetary systems around intermediate-mass stars. To date, about 10 planets have been discovered around them and the planets show different properties from those around lower-mass stars. We have been carrying out a Doppler survey of G and K giants at Okayama Astrophysical Observatory in Japan since 2001 and succeeded in discovering seveal planets so far. We here introduce the outline of our project and present latest results.

52007-11-28 Wed
14:00~15:00
R716
Dr. Changbom Park
[Korea Instituite for Advanced Study]
How does galaxy morphology change?
Abstract

We found the local environment set up by the nearest neighbor galaxy gives stong effects on the galaxy morphology. The probability for a galaxy to have an early morphological type depends critically on whether or not rho_n is above the virialization density. Large part of the morphology-local density relation is due to the correlation between rho_n and the large-scale background density. We also found that galaxy luminosity depends on rho_n, and that more isolated galaxies are more likely to be recent merger products. We propose a scenario that a series of morphology and luminosity transformation occur through distant interactions and mergers, which results in the morphology-luminosity-local density relation.

62007-11-23 Fri
14:00~15:00
R716
Dr. Patrick Cote
[Herzberg Institute of Astrophysics]
New Results on the Structure of Early-Type Galaxies: Two Dichotomies Disappear
Abstract

A total of 143 early-type members of the Virgo and Fornax Clusters have been observed with the Hubble Space Telescope (HST) as part of the ACS Virgo and Fornax Cluster Surveys. The surveys and their extensions consists of color imaging from the Advanced Camera for Surveys (ACS), supplemented by additional imaging and spectroscopy from WFPC2 HST, Chandra, CFHT, Spitzer, Keck, VLT, KPNO, and CTIO. In this talk, I will report briefly on how these surveys help to resolve two longstanding puzzles concerning the structure of early-type galaxies: i.e., the alleged dichotomies between "dwarfs" and "giants", and "core" and "powerlaw" galaxies.

72007-11-20 Tue
14:00~15:00
R716
Dr. Masako Yamada
[NAOJ]
Three Dimensional Radiative Transfer Study of Molecular Gas ; towards ALMA Era
Abstract

Molecular gas in external galaxies is a subject of crucial importance for observational and theoretical studies of galaxy formation. Among the interstellar medium (ISM) in external galaxies, compact molecular gas around an active galactic nuclei (AGN) is expected to be an energy budget from AGN and/or the central starburst. Recent observations suggest line ratios in millimeter and submillimeter band may be a good tool to reveal the long-standing question on the origin of activity, AGN or nuclear starburst. In spite of numerous observational studies towards the compact molecular gas or AGN torus at the center of external galaxies, current instruments have not succeeded in resolving internal hydrodynamical and/or thermal structures. We have constructed a powerful telescope of theory, three-dimensional nonLTE line transfer code, preceding the forthcoming high resolution and sensitivity observations, such as ALMA. In order to study the internal structures of AGN molecular torus, we performed line transfer calculations of CO, HCN, and HCO+ lines along with high resolution hydrodynamic simulation. Our RT results of complicated excitation conditions suggest that there would be cases that simple and popular LVG analysis cannot reveal correct physical properties. I am going to present some of our recent results of our 3D line transfer simulations of inhomogeneous ISM.

82007-11-16 Fri
12:30~13:30
R716
Dr. Dragan Huterer
[University of Michigan]
TBA
92007-11-16 Fri
14:00~15:00
R716
Dr. Loic Albert
[CFHT]
The Search for Very Cold Brown Dwarfs at the Canada-France-Hawaii Telescope
Abstract

In a short span of 12 years since the discovery of the first methanic Brown Dwarf, GJ 299B, a variety of classical studies done on main-sequence OBAFGKM stars over the course of the last century have been repeated on the newest spectral types, L and T, albeit at a much faster pace. These studies target the binary frequency, the galactic mass function, modelling the atmosphere, etc. The quest for even colder objects belonging to the elusive Y spectral type is more than ever raging. CFHT, with its two instruments, Megacam in the visible and WIRCam in the NIR, is particularly well suited to hunt for brown dwarfs, where wide-field coverage is the name of the game. I will describe a few projects done at CFHT whose objectives are to find cold brown dwarfs in the solar neighborhood and to characterize their binary frequency. Covering close to 1000 sq. degrees, the Canada France Brown Dwarf Survey (CFBDS) is already finding the coldest BDs at spectral types later than T8.5.

102007-11-15 Thu
15:30~16:30
R716
Dr. Keith Yeung
[NRC-HIA]
ALMA Band 3 Receiver Development
112007-11-02 Fri
14:00~15:00
R716
Dr. Frank Cheng
[NCKU]
Observation and Theory of Solar Flares
122007-10-31 Wed
14:00~15:00
R716
Dr. France Allard
[ENS, Lyon, France]
Extrasolar Planets
Abstract

The existence of extrasolar planets is among the most exciting discovery in history, challenging once more our specificity in the Universe. Their discovery has brought along some surprises constituting interesting challenges in astrophysics today. The presence of Hot Jupiters so close-in to their parent star has challenged planetary formation theories. The much larger radii of several transits has challenged interior and evolution theories. The detection of their atmosphere has challenged observational techniques. And the understanding of their spectral properties is challenged by the geometry of the problem, by possible fluid dynamics (mass-loss, winds, Coriolis forces, etc.), by departure from LTE in transit studies, and by cloud formation. Nevertheless, progress as been achieved. We will review findings leading to our current conception of the physical properties of exotrasolar planets.

132007-10-26 Fri
14:00~15:00
R716
Dr. Michel Guelin
[IRAM]
Identification of Interstellar Molecules: Beating the confusion at millimeter
142007-10-24 Wed
14:00~15:00
R716
Dr. Wei-Chun Jao
[Georgia State University]
Cool Subdwarf Investigations (CSI): spectral sequence
Abstract

Subdwarfs are the counterparts of dwarfs on the main sequence. Currently, K and M type subdwarfs spectral types are assigned by spectroscopic indices. I will discuss a new thought to properly assign their spectral types and how their spectra changes with effective temperature, metallicity and gravity. Besides, this proposed new typing method will be applied to other cool subdwarf spectra released to public to demonstrate its reliability.

152007-10-19 Fri
14:00~15:00
R716
Dr. Michel Guelin
[IRAM]
Cold matter in galaxies: new results of the IRAM telescopes
162007-10-05 Fri
14:00~15:00
R716
Prof. Lin-Ni Hau
[National Central University]
Interplay Between Theory and Observation in Space Plasma
172007-09-28 Fri
14:00~15:00
R716
Prof. W.-Y. Pauchy Hwang
[National Taiwan University]
What happened during the cosmological QCD phase transition?
182007-09-21 Fri
14:00~15:00
R716
Prof. James Nester
[National Central University]
Torsion Cosmology and the Oscillating Universe
Abstract

Investigations of the dynamic modes of the Poincare gauge theory of gravity found only two good propagating torsion modes; they are effectively a scalar and a pseudoscalar. Cosmology affords a natural situation where one might see observational effects of these modes. The scalar torsion mode has certain distinctive qualities; here we consider only this mode. Via numerical evolution of the coupled nonlinear equations we show that the scalar torsion mode can contribute an oscillating aspect to the expansion rate of the Universe. From the examination of specific cases of the parameters and initial conditions we show that for suitable ranges of the parameters the dynamic scalar torsion model can display features similar to those of the presently observed accelerating universe.

192007-08-29 Wed
14:00~15:00
R716
Dr. Sebastian Wolf
[Max Planck Institute for Astronomy]
Signatures of Planets in Circumstellar Disk
202007-08-16 Thu
14:00~15:00
R716
Dr. Phan, Bao Ngoc
[ASIAA]
Discovery of new nearby late-M and L dwarfs at low Galactic latitude and future plan to study the origins and evolution of brown dwarfs and extrasolar planets
Abstract

10 min for an overview of my research of low mass stars, brown dwarfs and planets: brown dwarf and planet search, magnetic field measurement in fully convective stars, radio emission from ultracool dwarfs, debris disk search around young field brown dwarfs. 25 min for determination of luminosity function and space density of brown dwarfs at low Galactic latitude, including the discovery of 21 new L and late-M dwarfs. 10 min for future plan to study the origins and evolution of brown dwarfs and extrasolar planets.

212007-08-10 Fri
14:00~15:00
R716
Dr. Simon Campbell
[ASIAA]
Structural Evolution & Chemical Pollution from the First and Second Stars
222007-07-27 Fri
14:00~15:00
R716
Dr. Yolanda Gomez
[Universidad Nacional Autonoma de Mexico]
Water maser emission in planetary nebulae
Abstract

Stars at the end of the asymptotic giant branch (AGB) can exhibit maser emission from molecules like SiO, H2O and OH. These masers appear in general stratified in the envelope, with the SiO masers close to the central star and the OH masers farther out in the envelope. As the star evolves to the planetary nebula (PN) phase, the AGB wind stops and ionization of the envelope begins, making the masers disappear. The OH masers in PNe can be present in the envelope for periods of ~1000 years but the water masers can survive only hundreds of years. Then, water maser emission is not expected in PNe and their detection suggests that these objects are in a very particular moment of its evolution in the transition from AGB to PNe or that water molecules can be protected from the radiation of the central star. We discuss the unambiguous detection of water maser emission in two planetary nebulae: K~3-35 and IRAS~17347-3139. The water-vapor masers in these PNe are tracing disk-like structures around the core and in the case of K3-35 the water masers were also found at the tip of its bipolar lobes. Kinematic modeling of the water masers in K 3-35 suggest the existence of a rotating and expanding disk. The recent detection of molecular gas toward K 3-35 supports the existence of a shielding mechanism that could be protecting the water molecules from the radiation of the central star.

232007-07-24 Tue
14:00~15:00
R833
Dr. Luis Rodriguez
[Universidad Nacional Autonoma de Mexico]
Massive Star Formation
Abstract

In the last two decades there has been great advance in our understanding of the formation of solar-mass stars. A major question related to galactic star formation is whether or not the successful model of low-mass star formation, based on accretion via a circumstellar disk and collimated outflow in the form of jets, can be extended to the case of high-mass protostars. However, the detection of jets and disks in high mass forming stars has proved to be very difficult. We discuss the observations made by several groups toward sources like Cep A HW2, HH 80-81, and IRAS 16547-4247 that have been interpreted as supporting the presence of jets and disks in these massive protostars. We finally discuss the evidence that in at least one region, Orion BN-KL, an alternative mechanism for the formation of massive stars, the merging of lower mass stars, maybe operating.

242007-07-13 Fri
14:00~15:00
R716
Dr. Satoko Takehashi
[ASIAA]
Structure and Evolution of Circumstellar Envelopes and Outflows in Intermediate-mass Protostars
252007-06-29 Fri
14:00~14:30
R716
Ms. Pei-Chun Hsu
[TIARA/ASIAA]
Particle Acceleration in Pulsar Magnetospheres
262007-06-26 Tue
14:00~14:30
R716
Ms. Nami Sakai
[University of Tokyo]
Detection of Negative Ion in Star Forming Regions
272007-06-26 Tue
14:30~15:00
R716
Mr. Takeshi Sakai
[Nobeyama Radio Observatory]
A Survey of Molecular Lines toward Massive Clumps associated with Infrared Dark Clouds
282007-06-22 Fri
14:00~15:00
R716
Prof. Xiao-Gang He
[NTU]
Dark Matter and Collider Physics
292007-06-15 Fri
14:00~15:00
R716
Dr. Jeremy Lim
[ASIAA]
The Riddle of X-ray Cooling Flows
Abstract

Rich groups and clusters of galaxies are immersed in hot (107-108 K) X-ray-emitting gas, which is cooling by virtue of its X-ray radiation. In many clusters, the cooling times are so short that we should see a flow of cool gas to the cluster center; i.e., a X-ray cooling flow. Although predicted 30 years ago, such cooling flows have yet to be definitively observed. Rather, in apparent contradiction with predictions, recent X-ray spectroscopy of putative cooling-flow clusters fail to find gas at about one-third the cluster virial temperature. Furthermore, X-ray imaging at high angular resolutions reveal that the X-ray gas at the centers of putative cooling-flow clusters is usually disturbed by radio jets from the central galaxy. These results suggest that the X-ray gas at the cluster center is reheated thereby diminishing if not preventing a cooling flow. In this presentation, we provide the strongest and perhaps first definitive evidence for cool gas deposited by a X-ray cooling flow. The observed properties of the cooling flow help to resolve many of the current paradoxes in the riddle of X-ray cooling flows.

302007-06-13 Wed
15:00~16:00
IAMS
Dr. Kenneth C. Chambers
[Institute for Astronomy, Hawaii]
The Pan-STARRS Telescope #1 (PS1) Science Mission and Sky Surveys
312007-05-31 Thu
14:00~15:00
R716
Prof. Jianning Fu
[Beijing Normal University]
Asteroseismology of the pulsating white dwarf star PG 0122+200
322007-05-31 Thu
15:30~16:30
R716
Dr. Lifan Wang
[Texas A&M University]
Astronomy at Antarctica Plateau
332007-05-30 Wed
14:00~15:00
R716
Dr. Houjun Mo
[University of Massachusetts]
Establish the relationship between galaxies and dark matter
342007-05-30 Wed
15:30~16:30
R716
Prof. Long-Long Feng
[Purple Mountain Observatory]
Computational Cosmology Powered by Multi-resolution Analysis (MRA)
352007-05-25 Fri
14:00~15:00
NTHU
Prof. Sergey Bastrukov
[Joint Institute for Nuclear Research, Russia]
Torsional Pulsations of Neutron Stars
362007-05-18 Fri
14:00~15:00
NTHU
Dr. Sujan Sengupta
[Indian Institute of Astrophysics, India/TIARA]
The Atmosphere of Brown Dwarfs
372007-05-11 Fri
14:00~15:00
NTHU
Dr. Daniel Espada
[ASIAA]
Neutral gas properties of galaxies: from the most isolated ones to radio-galaxies
Abstract

The environment of galaxies seems to play a key role in the evolution and formation of galaxies. The morphological appearance, ISM properties, star formation and nuclear activity are known to be conditioned by interactions between galaxies. In order to quantify what is the effect of the environment, an unbiased sample of galaxies free of interaction and with multiwavelength information is needed. To that aim, we are studying a numerous (~1000), well-defined and complete sample of isolated galaxies (AMIGA project, http://www.iaa.es/AMIGA.html) based on the Catalogue of Isolated Galaxies (Karatchenseva, 1973) and building a database that currently contains optical luminosities, Ha, FIR and NIR, radio-continuum, HI and CO(1-0) information. I focus in this talk on the neutral gas (both atomic and molecular) properties of these isolated galaxies and compare with other samples of nearby galaxies in denser environments where interactions events are more likely, such as Hickson compact groups. In particular, I will also discuss the mean properties of the neutral gas in nearby radio-galaxies and luminous IR galaxies with respect to our new reference of very isolated galaxies.

382007-05-10 Thu
14:00~15:00
IAMS
Dr. Alwyn Wootten
[NRAO]
Beyond ALMA's First Fringes
392007-05-04 Fri
14:00~15:00
R716
Dr. Ananda Hota
[ASIAA]
Radio continuum and HI study of gas-loss processes in nearby galaxies
Abstract

One of the prominent contributions towards the cosmic evolution of galaxies and inter-galactic medium could be from the gas-loss processes going on in galaxies. We have studied a number of galaxies in radio continuum and HI using both the VLA and the GMRT where different components of the interstellar medium are pushed outwards due to various gas-loss processes like starburst-driven superwinds, AGN-driven nuclear outflows, ram pressure stripping and tidal interactions. Severe kinematic effects of the superwind on the HI-ISM have been seen in the superwind galaxy NGC1482. Expanding shock wave from the outflow is possibly creating a starformation ring around it. We have found HI outflow to be associated with the molecular, ionised and synchrotron plasma outflow, possibly due to an young superwind, in the Seyfert galaxy NGC6764. In the disturbed Virgo cluster galaxy NGC4438, the complex HI velocity field of NGC4438 show diverging iso-velocity contours suggesting the affects of ram pressure from the cluster medium. We have tentatively discovered a 140 million solar-mass HI-tail of NGC4438 extending up to 75kpc from it to coincide with a faint stellar tail. As a rare example we have found evidences of ram pressure stripping in the member galaxies of the group Ho 124. Trailing velocity field of the one sided extra-planer HI-loop, HI-tails and down stream HI-accumulations are seen in them. Three galaxies in the cluster Abell 1367 are known to have 50-75 kpc long tails emitting radio continuum and H_alpha. We did not detect any HI in their tails but we find that 20-30% of excess HI-gas is accumulated on the down-stream sides of the disks, due to the affects of ram pressure from the cluster medium. In this talk I will summarise the results of our study and discuss the importance of studying such systems for better understanding of gas and galaxy evolution.

402007-04-27 Fri
14:00~15:00
R716
Dr. Evgeny Griv
[Ben-Gurion University]
Dynamics of Saturn's Rings
412007-04-20 Fri
14:00~15:00
NTHU
Dr. Chin-Fei Lee
[ASIAA]
Shaping of protoplanetary nebulae and young planetary nebulae
Abstract

Most stars end their lives the same way as the Sun, evolving first into red giants, then asymptotic giant branch (AGB) stars surrounded by circumstellar envelopes (CSEs), then post-AGB stars with pPNe, and finally into white dwarfs (WDs) with PNe. pPNe are the immediate progenitors of PNe and expected to evolve into PNe in less than 1000 years. Despite extensive studies, the origin and evolution of pPNe and PNe, which are the key questions to understanding the mass-loss mechanism during the end stages of the stellar evolution, are still uncertain. pPNe and PNe are now believed to be produced by collimated fast winds (CFWs) or jets. For the first time, we show that CFWs can reproduce some of the key features seen in protoplanetary and young planetary nebulae that can not be produced before by isotropic fast winds. This result changes our current understanding of the mass-loss mechanism at the end of the stellar evolution, which is assumed to be isotropic. In addition, we find that toroidal magnetic field is needed to constrain the jet material in the jet beam in order to reproduce the observed morphology and kinematics of the jet. This suggests that magnetic field may play a crucial role for launching the jet. Also, the observed periodical knots in the jet may suggest that the central system is binary.

422007-04-18 Wed
14:00~15:00
R716
Dr. Sandor Molnar
[University of Zurich]
Slow Accretion Shocks in Clusters of Galaxies: Comparing SPH and AMR Simulations
Abstract

The emergence of slow accretion shocks generated by secondary in-fall in clusters of galaxies is an inevitable prediction of our structure formation (CDM) models. Observations of these shocks would be an important confirmation of our structure formation models. We have been analyzing clusters of galaxies drawn from SPH (G. Evrard) and AMR (G. Bryan) simulations. This work is still in progress, here I show our latest results. The preliminary analysis shows that these shocks are between 1 and 2 virial radii of the cluster depending on the details of the physics included. Clusters of galaxies are large reservoirs of matter, therefore understanding the spatial distribution of matter within clusters is very important in cosmology. The latest results show that about 20% of the baryons are missing in clusters of galaxies (Afshordi et al. 2006). We have also studied the large scale distribution of gas in the simulated clusters and found that, since the gas extends beyond the virial radius, a significant amount of baryons can be stored just outside the virial radius. Observations of the extent of gas in clusters therefore would provide very important clues to structure formation and cosmology. Our results can be used to study the feasibility of observing slow accretion shocks and the large scale distribution of baryons in clusters with the new generation of SZ instruments, such as AMiBA.

432007-03-29 Thu
14:00~15:00
R716
Dr. Christopher Deloye
[Northwestern University]
Too Close for Comfort? The Physics of Starting and Surviving Mass Transfer in Close White Dwarf-White Dwarf Binaries
442007-03-27 Tue
14:00~15:00
R716
Prof. Frank Shu
[UCSD]
Mean-Field MHD of Accretion Disks in YSOs
452007-03-21 Wed
14:00~15:00
R716
Prof. You-Hua Chu
[University of Illinois at Urbana-Champaign]
Comets around the Central Star of the Helix Nebula
462007-03-20 Tue
11:00~12:00
R716
Dr. Daisuke Kawata
[Carnegie Observatories]
The Virtual Group Catalog Project
472007-03-20 Tue
14:00~15:00
R716
Dr. Kazushi Sakamoto
[NAOJ]
SMA Observations of Starbursts in the South and in the Submillimeter
Abstract

More than three years have passed since the dedication of the Submillimeter Array (SMA). The SMA has allowed us high-resolution imaging in the submillimeter wavelengths and in the southern sky that are not readily accessible for the existing millimeter arrays. I have been observing starburst galaxies in the submillimeter and/or in the southern sky to make the most use of the SMA's unique capabilities. The ongoing campaign has already resulted in discoveries of superbubbles, a superwind, CO-hotspots associated with super clusters, hot molecular cores, and complex gas dynamics in merger nuclei. These are basic elements of the complex interplay between the ISM and the starburst. I review the highlights of our starburst observations and discuss what we need to do (with the SMA and the ALMA) to further understand the starburst phenomenon.

482007-03-16 Fri
14:00~15:00
R716
Dr. Ue-Li Pen
[CITA]
A Software correlator for GMRT
492007-03-09 Fri
14:00~15:00
R716
Dr. Lung-Yih Chiang
[Niels Bohr Institute]
The "Axis of Evil" and cosmic anomalies in the WMAP data
502007-02-15 Thu
14:00~15:00
R716
Dr. Shigehisa Takakuwa
[NAOJ]
Observations of Chemical Differentiation in Clumpy Molecular Clouds
Abstract

In this colloquium, I will talk about our recent results on chemical differentiation in molecular clouds. We have been making extensive mapping observations of molecular clouds in several 3-mm molecular lines, such as CH3OH, H13CO+, and SO lines, with the Nobeyama 45-m telescope and the Onsala 20-m telescope. Our observations show that there are ``clumpy'', fine-scale chemical differentiations down to the 0.01 pc scale in molecular clouds. These chemical differentiations can not fully be explained by current chemical evolutional models, which can explain chemical difference between starless and protostellar cores in molecular clouds and systematic chemical variation as a function of the core radius. We suggest that chemical modelings with the detail clump dynamics are required to fully understand the observational results.

512007-02-15 Thu
15:30~16:30
R716
Dr. Hiro Takami
[NAOJ]
Observational Studies of Jets/Outflows Associated With YSOs: From Subaru/Gemini/ASTE To ALMA
522007-02-14 Wed
14:00~15:00
R716
Dr. Kuiyun Huang
[National Central University]
Gamma-ray Burst Optical Afterglow Observations at Lulin Observatory
Abstract

Gamma-ray bursts (GRBs) are among the most powerful explosions in the universe. Astronomers did not know their origin and mechanisms until the afterglows were discovered in 1997. The optical afterglow observations showed that GRBs are cosmological (their redshift distribute from 0.009 to 6.29), and several long duration GRBs are accompanying with supernovae. The detection of optical transient associated with bursts thus became important. Our Lulin GRB program started GRB optical follow-up observations since July 2003. This program proposes to discover optical afterglows of long- and short-GRB and X-ray flash then obtain their temporal and spectral evolution by Lulin One-meter Telescope (LOT). The LOT, a major site of the East-Asia GRB Follow-up observation Network (EAFON), performed 43 follow-up observations and totally seventeen optical afterglows detected until February 2007. In this presentation, I will present our results of the optical afterglows, especially for GRB 040924 -- an unusual short duration burst and GRB 050319 -- a afterglow with shallow decay and chromatic breaks.

532007-02-08 Thu
14:00~15:00
R716
Dr. Daisuke Iono
[NAOJ]
High Resolution mm/submm Observations of Starbursting Galaxies Near and Far
Abstract

The discovery of FIR/submm bright galaxies has advanced our understanding of formation and evolution of galaxies. In the local universe, extensive multi-wavelength observations toward FIR bright galaxies (i.e. U/LIRGs) have revealed that these systems are compact, often dominated by starbursts, and morphologically disturbed. In the distant universe, the SCUBA bolometer onboard JCMT has successfully detected a number of faint and distant submm bright sources, but the coarse angular resolution given by the JCMT has made the identification of the exact optical/NIR counterpart extremely difficult. The radio-FIR correlation allows us to indirectly identify the optical/NIR counterparts using radio interferometers such as the VLA. However, the radio emission is detectable only up to moderately high redshifts (z = 2 - 3), and the potentially more distant submm galaxies are largely unexplored. For sources with robust radio counterparts, existing mm/submm instruments can probe the amount of cold molecular gas present in the galaxy, provided that follow-up optical spectroscopy yields accurate redshifts. For sources without (or with multiple) radio detections, the only way to identify the exact optical/NIR counterpart is to use sensitive and high resolution submm interferometers. The Submillimeter Array (SMA) now allows us carry out this task. Armed with the 1 - 2 mJy sensitivity and sub-arcsecond astrometry, we can now search for the exact location where the bright submm emission comes from. The SMA also allows us to study the FIR bright galaxies in the local universe with unprecedented resolution and sensitivity in the submm, allowing us to make direct comparisons with the properties in high-z galaxies. In this talk I will present some of our recent results of dust continuum observations toward submm galaxies obtained at the SMA. I will also present our new CO(3-2) observations toward NGC6240, which is a LIRG that is included in our ongoing SMA survey of local U/LIRGs. Further, I will present preliminary results from our comparison of gas properties between local U/LIRGs and high-z galaxies. I will conclude this talk with future prospects using the ALMA telescope.

542007-02-07 Wed
14:00~15:00
R716
Dr. Kinwah Wu
[University College London]
Emission from accreting black holes - general relativistic radiative transfer
552007-02-01 Thu
14:00~15:00
R716
Prof. Shih-Ping Lai
[National Tsing-Hua University]
New results from Spitzer's "From Cores to Disk" Legacy Project
Abstract

The unprecedented sensitivity of Spitzer Space Telescope at 3-160 micron provides crucial data for studies of star and planet formation. The "From Molecular Cores to Planet Forming Disk" (c2d) project is one of the original Legacy Projects which uses 400 hrs to observe five nearby molecular clouds, 86 dense cores, and 190 known young stars. The results of the c2d project uncovered hundred thousands of previous unknown sources, providing the first unbiased sample for statistical studies of the complete stellar content and star formation history in the survey regions. Till now 34 papers have been published based on the c2d data. This talk summarizes the key contrubutions of the c2d project to our understanding of star formation.

562007-01-26 Fri
14:00~15:00
R716
Prof. Joe Shields
[Ohio University]
Black Holes and Star Clusters in Galaxy Nuclei
572007-01-12 Fri
14:00~15:00
R716
Dr. Satoki Matsushita
[ASIAA]
Molecular gas around AGNs: Imaging down to 10 pc from central engines
TEL: 886-2-3365-2200 FAX: 886-2-2367-7849
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