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Activity > Lunch Talk

Lunch Talk (2024)

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.

    Contact
  • Lunch Talk: Colloquium Committee (talks_replace2@_asiaa.sinica.edu.tw)
  • Tech Lunch Talk: Chang, Hsiao-Wen (hwchang_replace2@_asiaa.sinica.edu.tw)
NEXT Lunch Talk: 2024-03-04 Mon 12:00~12:40 [R1412]
Speaker:Sheng-Yuan Liu
No. Time/Place Speaker Topic (Abstract)
download PDF: dowaload talk PDF file
12024-05-06 Mon
12:00~12:40
R1412
Shouvik Roy Choudhury
[ASIAA]
Massive neutrino self-interactions and the Hubble tension
22024-04-29 Mon
12:00~12:40
R1412
Dan Luo (羅丹)
[AS Counseling Center]
Caring and a general introduction to the AS counseling center (如何關心他人以及介紹關懷中心)
32024-04-22 Mon
12:00~12:40
R1412
Ming-Jye Wang
[ASIAA]
Toward a 100-pixel heterodyne sub-mm receiver
42024-04-15 Mon
12:00~12:40
R1412
Shih-Hao Wang
[ASIAA]
Probing the Universe with ultra-high energy cosmic neutrinos beyond 100 PeV
52024-04-08 Mon
12:00~12:40
R1412
Travis Thieme
[ASIAA]
62024-04-01 Mon
12:00~12:40
R1412
Bovornpratch Vijarnwannaluk
[ASIAA]
72024-03-18 Mon
12:00~12:40
R1412
Ryan Keenan
[Educational technology industry]
82024-03-11 Mon
12:00~12:40
R1412
Aisling Murphy
[ASIAA]
92024-03-04 Mon
12:00~12:40
R1412
Sheng-Yuan Liu
[ASIAA]
102024-02-19 Mon
12:00~12:40
R1412
You-Hua Chu
[ASIAA]
Academic Writing
112024-02-05 Mon
12:00~12:40
R1412
Bandy Shang
[TASA]
Career experience sharing: from astro to space engineering
122024-01-29 Mon
12:00~12:40
R1412
Yu-Hsuan (Eltha) Teng
[UCSD]
Re-evaluating Star Formation Efficiencies with a New CO-to-H2 Conversion Factor Prescription
Abstract

Star formation in galaxies is governed by the amount of molecular gas and the efficiency that gas is converted into stars. However, assessing the amount of molecular gas relies on the CO-to-H2 conversion factor (α_CO), which is known to vary with molecular gas conditions like density, temperature, and dynamical state – the same conditions that also alter star formation efficiency. The variation of α_CO, particularly in galaxy centers where α_CO can drop by nearly an order of magnitude, thus causes major uncertainties in current molecular gas and star formation efficiency measurements. Using ALMA observations of multiple 12CO, 13CO, and C18O lines in several barred galaxy centers, we found that α_CO is primarily driven by CO opacity changes and therefore shows strong correlations with observables like velocity dispersion and 12CO/13CO line ratio. Motivated by these results, we have established a new α_CO prescription which accounts for CO emissivity variations and verified it across a set of nearby galaxies with independent α_CO measurements from dust. Applying our new prescription to 65 galaxies from the PHANGS-ALMA survey, we found an overall 3x higher star formation efficiency in barred than non-barred galaxy centers, which is an unprecedented trend that has been obscured by past α_CO prescriptions. Our results suggest that the high star formation rates observed in barred galaxy centers is mainly due to an enhanced star formation efficiency, rather than a substantially increased amount of molecular gas.

132024-01-15 Mon
12:00~12:40
R1412
Kai-Yang Lin
[ASIAA]
BURSTT Development
Abstract

Fast Radio Bursts (FRBs) have been shown to have diverse properties and may come from very different host environments. To better understand the FRBs' origin, multi-wavelength detailed studies of a large sample of nearby FRB hosts will provide valuable information. To fulfill this goal, BURSTT has been designed with a large field of view and sub-arcsecond localization capabilities. In this talk, I will introduce the BURSTT project and its development status, focusing on the backend system, calibration, and VLBI timing I mainly work on.

TEL: 886-2-3365-2200 FAX: 886-2-2367-7849
General: asiaa_replace2@_asiaa.sinica.edu.tw Media Request: epo_replace2@_asiaa.sinica.edu.tw
11F of AS/NTU Astronomy-Mathematics Building, No.1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan, R.O.C.