Academia Sinica Institute of Astronomy & Astrophysics
中央研究院天文及天文物理研究所
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Activity > Lunch Talk

Lunch Talk (2017)

ASIAA Lunch Talk is an institute-wide event allowing ASIAA researchers from different fields to discuss astronomy in a very casual manner. The informal meeting is usually held at lunch time on every Monday. Occasionally visitors are also invited to the lunch talk to share their research and ideas with ASIAA researchers.

NEXT Lunch Talk: 2017-11-20 Mon 12:00~13:00 [R1203]
Speaker:Keiichi Asada
Topic:Mass accretion flow onto SMBH probed with mm polarimetric observations
No. Time/Place Speaker Topic (Abstract)
download PDF: dowaload talk PDF file
12017-12-18 Mon
12:00~13:00
R1203
Hsien Shang
[ASIAA]
22017-12-11 Mon
12:00~13:00
R1203
James Simpson
[ASIAA]
32017-12-04 Mon
12:00~13:00
R1203
Sacha Hony
[University of Heidelberg]
Indications of IMF variations based on the occurrence rates of high-mass stars in Milky Way stellar clusters
Abstract

I will present the results of a study (Dib, Schmeja & Hony 2017) to investigate the occurence rates of single high-mass stars in clusters in order to put constraints on the IMF. The key idea is that the for small clusters (of a few hundred solar masses) that have trouble to make an O-type star this occurence rate will depend strongly on the IMF. We compare the fractions of single and lonely massive O stars in a recent catalogue of the Milky Way clusters with a library of simulated clusters built with various distribution functions of the IMF parameters. The synthetic clusters are corrected for the effects of the binary population, stellar evolution and sample incompleteness. Our findings indicate that significant cluster-to-cluster variations of the IMF parameters are required in order to reproduce the fractions of single and lonely O stars in Galactic clusters.

42017-11-22 Wed
12:00~13:00
R1203
Hsieh, Hsun
[ASIAA]
Growth and superconducting properties of ultra-thin NbN films on 3C SiC/Si substrates
52017-11-20 Mon
12:00~13:00
R1203
Keiichi Asada
[ASIAA]
Mass accretion flow onto SMBH probed with mm polarimetric observations
62017-11-13 Mon
12:00~13:00
R1203
Jakub Ripa
[Formerly NTU]
Testing Isotropic Universe via Properties of Gamma-Ray Bursts Detected by Fermi / GBM
Abstract

The sky distribution of Gamma-Ray Bursts (GRBs) has been intensively studied for more than two decades. Most of these studies, test the isotropy of GRBs based on the sky number density distribution. We propose a new method which inspects the isotropy of the properties of GRBs such as their duration, fluences and peak fluxes at various energy bands and different time scales. The method was applied on the Fermi / Gamma-ray Burst Monitor data. We found a relatively significant feature near the Galactic coordinates approximately l = 30 deg, b = 15 deg and radius r = 20 - 40 deg with the inferred probability for the occurrence of such signal (in a random isotropic sample) to be less than a percent. However, more comprehensive analysis using different statistical tests and different samples show that the detected feature can be due to statistical fluctuations. Investigations on the updated Fermi / GBM sample as well as on the data sets of other instruments can clarify on the issue.

72017-11-08 Wed
12:00~13:00
R1203
Hsu, Shu-Fu
[ASIAA]
Subaru PFS Project: Aquisition & Guiding Camera Data Storage/Load
82017-11-06 Mon
12:00~13:00
R1203
Shoko Koyama
[ASIAA]
Study of the blazer Mrk 501 with mm-VLBI
92017-10-30 Mon
12:00~13:00
R1203
Keiichi Umetsu
[ASIAA]
Formation and Evolution of Cosmic Giants: Lensing View of Galaxy Cluster Halos
Abstract

I will talk about the discovery of a "plane" dictating dark-matter halo evolution from our gravitational lensing and X-ray observations. We show that high-mass galaxy clusters—cosmic giants formed in the universe—lie on a plane in the 3D logarithmic space of their characteristic halo radius "rs", mass "Ms" , and X-ray temperature "Tx" with a very small orthogonal scatter. The tight correlation indicates that the gas temperature was determined at a specific cluster formation time, which is encoded in (rs,Ms) and that the gas was heated when the clusters were in the fast-growing phase. Intriguingly, the plane is significantly tilted with respect to the canonical virial expectation, Tx ∝ Ms /rs. We show that the self-similar solution of Bertschinger (1985) for secondary infall and accretion can explain the observed relation, Tx ∝ Ms^1.5 /rs^2. Numerical simulations reproduce the observed plane and its angle. This result holds independently of the gas physics implemented in the code, revealing the fundamental origin of this plane.

102017-10-25 Wed
12:00~13:00
R1203
Jian, Shou-Ting
[ASIAA]
ALMA Band-1 2nd Beam Setting in Taichung
112017-10-23 Mon
12:00~13:00
R1203
Yuichi Higuchi
[ASIAA]
Measuring the mass distribution toward the CMB Cold Spot with weak gravitational lensing
122017-10-02 Mon
12:00~13:00
R1203
Masanori Nakamura
[ASIAA]
Fundamentals of MHD Jets
Abstract

The Magnetohydrodynamic (MHD) jet/wind model, which is the very popular theory of astrophysical jets (in such as YSOs and AGNs), is briefly discussed. The "magneto-centrifugal" (MC) acceleration (Blandford & Payne 1982, MNRAS, hereafter BP82) plays a primal role in sub-Alfvenic regime, but there are many misunderstandings in the literature. It is nice to consider the MC process in the inertial frame to see what is essential for the MC acceleration. The standard solution of BP82 includes the magnetic pressure gradient (MPG) acceleration; both the MC and the MPG process would take place in a single streamline of the MHD jet in trans-Alfvenic regime. The talk aims to share fundamentals of MHD jets with undergraduate knowledge, especially with those who are not experts in this field.

132017-09-27 Wed
12:00~13:00
R1203
Huang, Pin Jie
[ASIAA]
PFS METROLOGY CAMERA CARBON FIBER TUBE TMA TEST
142017-09-25 Mon
12:00~13:00
R1203
Wei-Hao Wang
[ASIAA]
My trip to watch the 2017 North American total solar eclipse
Abstract

Non-research staff are welcome.

152017-09-18 Mon
12:00~13:00
R1203
Kai-yang Lin
[ASIAA]
Report on the intensity mapping workshop
162017-09-13 Wed
12:00~13:00
R1203
Chien, Chen
[ASIAA]
OMT Design for Nobeyama Observatory
172017-09-11 Mon
12:00~13:00
R1203
Chin-Fei Lee
[ASIAA]
Hungry Baby Star Eating A Space Hamburger
182017-08-21 Mon
12:00~13:00
R1203
Ya-Wen Tang
[ASIAA]
Internal share archive of ALMA data
Abstract

Beside the regular PI projects of ALMA, one can also utilize the public ALMA data for his/her own research. In this talk, I will present the motivation why we need an interval share data archive and the plan.

192017-08-16 Wed
12:00~13:00
R1203
Wang, Chun-Lun
[ASIAA]
Electron Beam Lithography of HEB Mixers
202017-08-07 Mon
12:00~13:00
R1203
Ying-Tung (Charles) Chen
[ASIAA]
Exploring the 2:1 resonance using the Outer Solar System Origin Survey
212017-08-02 Wed
12:00~13:00
R1203
Shuay-Pwu Patty Ho
[Princeton]
Review of Techniques for Large Detector Array Packages on ACT for Cosmic Microwave Background
Abstract

The cosmic microwave background (CMB) continues to reveal new aspects of the large scale universe. Technologies for ground-based and balloon-borne instruments measuring the polarization of the CMB have been well established and advanced in the last decade. Experience from the current generation of CMB projects indicates that the integration of the cryogenic detector array package, including its multiplexing and readout elements, is critical to the performance of the CMB instrument. The next generation of instruments needed to fully explore the potential of the CMB will require many more detectors than have currently been deployed. As the number of detectors per focal plane scales up, improvements and new technologies for large array packaging will be required. In this talk, I will present the concept from ACTPol and Advanced ACTPol for the assembly of large bolometer arrays. I will summarize the possible improvements and limitations anticipated in driving towards large numbers of even higher density detector arrays when comparing to the successes from other CMB projects, keeping in mind the need for faster production rates while maintaining good performance and high yield.

222017-07-31 Mon
12:00~13:00
R1203
Yoshiki Toba
[ASIAA]
Search for extremely-luminous infrared galaxies ~follow up observations with SCUBA-2/JCMT and SMA~
232017-07-24 Mon
12:00~13:00
R1203
Shohei Aoyama
[ASIAA]
Cosmological simulation with Dust Formation and Destruction
Abstract

Dust is an essential component in understanding star formation properties of galaxies both observationally and theoretically. When we consider the absorption of UV light by dust, the dust abundance and the grain size distribution are both important. Dust is formed and destroyed in multiple processes, which depend on the local metallicity, density and temperature. We implement these processes of dust into hydrodynamic simulation code GADGET3-Osaka taking into account of the evolution of dust size distribution. In order to realize it, we include dust formation end destruction processes in ISM, which are not only generation and destruction by supernovae but also accretion, coagulation and shattering. We obtained the time evolution of the abundance $Omega_{\rm dust}(z)$, the mass function and the relation between dust-to-gas mass ratio to metallicity of each galaxy. They agree well with the corresponding observations.

242017-07-19 Wed
12:00~13:00
R1203
Chen, Hsin-Yo
[ASIAA]
TAOS2 Camera Dewar Design
252017-07-17 Mon
12:00~13:00
R1203
Wei-Hao Wang
[ASIAA]
New JCMT large programs
262017-07-10 Mon
12:00~13:00
R1203
Alfonso Trejo-Cruz
[ASIAA]
ALMA ARC activity
272017-07-05 Wed
12:00~13:00
R1203
Huang, Yen-Ru
[ASIAA]
Introduction of the FTIR System for Testing Terahertz Components
282017-06-26 Mon
12:00~13:00
R1203
Ui-Han Zhang
[NTU]
Magnetohydrodynamics with GAMER
Abstract

GAMER, a parallel Graphic-processing-unit-accerelated Adaptive-MEsh-Refinement hydrodynamic code, has been extended to support magnetohydrodynamics (MHD), where the solver for MHD features the corner-transport-upwind (CTU) scheme with the constraint transport (CT) technique. The divergent preserving operator for adaptive mesh refinement (AMR) has been applied to reinforce the divergence-free constraint on the magnetic field. GAMER-MHD has fully exploited concurrent executions of the MHD solver of GPU computation and others, including AMR, of CPU computation, and nearly 100% overlap in GPU and CPU computation is observed. Various standard tests of one-dimensional, two-dimensional and three-dimesional problems have been performed, and these tests show that GAMER-MHD is robust producing results either demosntrating the expected second-order accuracy of our numerical scheme or as good as those given by high-resolution uniform-grid runs. A new 3D MHD test problem has been explored, where the magnetic field assumes the Arnold- Beltrami-Childress (ABC) configuration that can be unstable, temporarily becomes turbulent with thin-tube reconnection and finally settles to a lowest-energy equilibrium state. This 3D problem is adopted for the performance test of GAMER-MHD in a supercomputer equipped with top-end GPU and CPU. The single-GPU performance can reach 2 × 10^7 cell-update/sec, and this code also shows high efficiency of parallelization and scalability up to O(10^3) nodes.

292017-06-19 Mon
12:00~13:00
R1203
Lapo Fanciullo
[ASIAA]
Determining the Systematic Errors in Fits of Dust Thermal Emission: The Role of Laboratory Data in Upcoming Models
302017-06-12 Mon
12:00~13:00
R1203
Yusuke Aso
[ASIAA]
ALMA observations of a very young protostar newly found in Serpens Main
312017-06-07 Wed
12:00~13:00
R1203
Lu, Wei-Chun
[ASIAA]
Introduction of Lapping and Polishing Machines for Terahertz Applications
322017-05-24 Wed
12:00~13:00
R1203
Yang, Ping-Hsueh
[ASIAA]
GBT-800 Antenna Simulation Using CST EM-tool
332017-05-15 Mon
12:00~13:00
R1203
Kuan-Chou Hou
[ASIAA]
Dust enrichment in galaxy and cosmology simulations
342017-05-10 Wed
12:00~13:00
R1203
Yen, Sheng-Feng
[ASIAA]
wSMA series: My Baker Life - The LDPE Anti-reflection Coating
Abstract

In this talk, I will mention why we need and quartz windows. And why using LDPE to reduce the reflection. How we coated the LDPE ( Low-density polyethylene ) at the quartz surface. And preliminary result.

352017-05-08 Mon
12:00~13:00
R1203
Satoki Matsushita
[ASIAA]
Working in Greenland in the Middle of Winter
362017-04-26 Wed
12:00~13:00
R1203
Chang, Yin-Chang
[ASIAA]
The TAOS 2 Camera Dewar Assembly
372017-04-24 Mon
12:00~13:00
R1203
Kota Naito
[ASIAA/NTU]
Statistical Study on Organic Inclusions in Meteorites
382017-04-17 Mon
12:00~13:00
R1203
Min-Kai Lin
[ASIAA]
Dusty disk-planet simulations
Abstract

I will present ongoing simulations to study the interaction between protoplanetary disks and embedded protoplanets using a modified version of the PLUTO code. I will show how dusty disk-planet torques can differ from that in pure gas disks, which is considered in most previous studies.

392017-04-12 Wed
12:00~13:00
R1203
Chiang, Po-Han
[ASIAA]
402017-03-29 Wed
12:00~13:00
R1203
Chiu, Chuang Ping
[ASIAA]
1.5THz Cartridge System
412017-03-27 Mon
12:00~13:00
R1203
Peter Scicluna
[ASIAA]
Observing mass-loss from evolved massive stars
422017-03-15 Wed
12:00~13:00
R1203
Chueh-Yi Chou
[ASIAA]
PFS fiber probe calibration unit
432017-03-01 Wed
12:00~13:00
R1203
Yen-Bin Chang
[ASIAA]
Fabrication of orthomode transducer for wSMA
442017-02-20 Mon
12:00~13:00
R1203
Kouichi Hirotani
[ASIAA]
Emission from the direct vicinity of black holes
Abstract

In a black hole magnetosphere, when the plasma accretion rate is much lower than the Eddington limit, a strong electric field inevitably appears along the magnetic field lines due to charge deficit. In such a charge-starved region (or a gap), the electric field accelerates migratory electrons and positrons into ultra relativistic energies. These relativistic leptons emit copious gamma-rays via curvature and inverse-Compton (IC) processes. Some of such gamma-rays collide with the submillimeter-IR photons emitted from the radiatively inefficient accretion flow (RIAF) to materialize as pairs. The created pairs polarize to partially screen the original acceleration electric field. By solving this pair-creation cascade self-consistently for the first time, we find that the gap emissions from the direct vicinity of stellar-mass, intermediate-mass, and super-massive black holes are detectable with Fermi/LAT and Imaging Atmospheric Cherenkov Telescopes (e.g., MAGIC, HESS, VERITAS, and CTA) when the accretion rate is in a certain range. Moreover, such HE/VHE gamma-ray fluxes are predicted to exhibit anti-correlation with the RIAF submillimeter fluxes, which enables us to discriminate the gap emission from the standard, shock-in-jet model, e.g., by using ALMA and CTA.

452017-02-15 Wed
12:00~13:00
R1203
Li Chao-Te
[ASIAA]
Millimeter Wave Grating Spectrometer for TIME
462017-02-13 Mon
12:00~13:00
R1203
Youichi Ohyama
[ASIAA]
Proposing to Subaru
472017-02-06 Mon
12:00~13:00
R1203
Ai-Lei Sun
[ASIAA]
Characterizing AGN [OIII] Extended Emission Line Regions with SDSS Images.
482017-01-18 Wed
12:00~13:00
R1203
Chen, Chung-Cheng
[ASIAA]
When Something is Broken...
492017-01-09 Mon
12:00~13:00
R1203
Shiang-Yu Wang
[ASIAA]
the Chinese large optical telescope projects
502017-01-04 Wed
12:00~13:00
R1203
Ling Hung-Hsu
[ASIAA]
Detector quality assurance for astronomy instrumentation
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