Special Colloquium

時間：10月14日(三) 16：00 ~ 17：20

題目：Probing Compact Objects: From Magnetar Activity to Accretion Dynamics

講者：胡欽評 教授

服務單位：國立彰化師範大學 物理學系

地點：本校科學三館1樓SC160

摘要：

Compact objects are natural laboratories for studying physics under extreme conditions. Starting with X-ray and gamma-ray observations, my research also draws on radio, optical, and gravitational-wave studies to understand how these systems behave. In this talk, I will focus on two questions: what causes changes in the emission of neutron stars, especially magnetars, and how compact objects interact with surrounding materials. I will first discuss our studies of magnetar emission and activity, using SGR 1935+2154 as a key example. Broadband, high-cadence X-ray observations have helped us identify glitches and track changes in its X-ray spectrum. These results help us investigate processes in the neutron-star interior and magnetosphere and explore their possible links to fast radio bursts. I will then turn to accreting compact objects, including a closer look at SMC X-1, a local analogue of ultraluminous X-ray pulsars. The evolution of its spin period and its long-term X-ray flux modulation provide clues to both the accretion flow and the geometry of the surrounding disk. Finally, I will discuss the roles of time-frequency analysis and NinjaSat observations in these studies, as well as our ongoing X-ray detector development for future observations.

• 對象：全校大學部及研究所同學(不限科系)
• 地點：國立陽明交通大學 新竹光復校區科學三館SC106

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11/5

臺灣無人機產業的發展與機會

11/19

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11/26

馬太鞍堰塞湖潰決之後，危險結束了嗎？——從大地的振動，重新理解山與河

12/3

當貝多芬走進電影院：電影中的古典音樂密碼

時間：9月17日(四) 13：20 ~ 15：10

題目：A Search for Planet Nine with IRAS and AKARI Data

講者：後藤友嗣 教授

服務單位：國立清華大學 物理學系

地點：本校科學三館1樓 SC157

摘要：The outer solar system is theoretically predicted to harbour an undiscovered planet, often referred to as P9. Simulations suggest that its gravitational influence could explain the unusual clustering of minor bodies in the Kuiper Belt. However, no observational evidence for P9 has been found so far, as its predicted orbit lies far beyond Neptune, where it reflects only a faint amount of Sunlight. This work aims to find P9 candidates by taking advantage of two far-infrared all-sky surveys, which are IRAS and AKARI. The epochs of these two surveys were separated by 23 years, which is large enough to detect the ~3’/year orbital motion of P9. We use a dedicated AKARI Far-Infrared point source list for our P9 search – AKARI Monthly Unconfirmed Source List, which includes sources detected repeatedly only in hours timescale, but not after months. We search for objects that moved slowly between IRAS and AKARI detections given in the catalogues. First, we estimated the expected flux and orbital motion of P9 by assuming its mass, distance, and effective temperature to ensure it can be detected by IRAS and AKARI, then applied the positional and flux selection criteria to narrow down the number of sources from the catalogues. Next, we produced all possible candidate pairs whose angular separations were limited between 42′ and 69.6′, corresponding to the heliocentric distance range of 500 – 700 AU and the mass range of 7 – 17 Earth masses. There are 13 pairs obtained after the selection criteria. After image inspection, we found one good candidate, of which the IRAS source is absent from the same coordinate in the AKARI image after 23 years and vice versa. However, AKARI and IRAS detections are not enough to determine the full orbit of this candidate. This issue leads to the need for follow-up observations, which will determine the Keplerian motion of our candidate.

 

時間：6月4日(四) 13：20 ~ 15：10

題目：Probing Magnetar Science in the NICER Era

講者：胡欽評 副教授

服務單位：國立彰化師範大學 物理學系

地點：本校科學三館1樓 SC157