類別:http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/622026-04-03T23:49:19Z2026-04-03T23:49:19Z黑洞之 “洛芙係數”Kai-Der Wang王塏德http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/664712021-06-17T00:37:29Z2019-01-01T00:00:00Z標題: 黑洞之 “洛芙係數”; Black Holes Tidal Love Numbers
作者: Kai-Der Wang; 王塏德
摘要: “洛芙係數” 這個物理量涵蓋了天體上一些極緊緻星體的資訊，例如黑洞或中子星。更重要的是我們在未來有機會能測到這個物理量。在廣義相對論中給出的黑洞解，經過計算發現竟然是零，這好比開出了一扇窗讓我們去真正的探索時空的本質。基於黑洞的“洛芙係數” 是零這個奇怪的事實跟愛因斯坦的理論只是有效場理論，也就是在四維時空裡的廣義相對論，我們知道當系統能量夠高時這理論需要一些高階修正項。在這篇文章中，我們分析了在這些高階修正下的黑洞解。我們在新的黑洞解的背景下做線性的微擾，並解了微擾的方程式。在適當的邊界條件下，我們可以提取黑洞的“洛芙係數” 這個資訊。我們發現在這新的黑洞背景下做微擾展開會得出不為零的“洛芙係數”。這更加深了在原本廣義相對論裡，黑洞的“洛芙係數”都是零謎。; The tidal Love numbers (TLNs) encode the internal structure of compact objects, such as black holes (BHs) or neutron stars and, more importantly, it is testable in the future gravitational detector. The vanishing of TLNs in vacuum classical general relativity thus offers a fantastic opportunity to probe the very fabric of spacetime, in the advent of a new era of precision gravity.Motivated by the bizarre features that BHs TLNs are all zero and the fact that Einstein’s gravity may not be well-behaved theory in high enough energy scale, we analyze black holes solutions under R^3-type corrections, which is the leading correction induced by quantum corrections in four-dimensions.Our methodology stars with the perturbation of our BHs solutions using a linear perturbation formalism. We then impose the Regge-Wheeler gauge and solve the perturbed differential equations using appropriate boundary conditions, both at the event horizon and infinity. From the resulting solutions, we can identify the induced multipole moments and the tidal fields which allow us to extract TLNs. We showed that perturbations around this black hole background will lead to non-zero TLNs. This further accentuates the “unnaturalness” of the vanishing TLNs for Schwarzschild black hole under Einstein-Hilbert action.2019-01-01T00:00:00Z高質量恆星形成區中氫化二氮陽離子之化學演化Wen-Tse Chien錢玟澤http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/80752021-05-20T00:48:44Z2020-01-01T00:00:00Z標題: 高質量恆星形成區中氫化二氮陽離子之化學演化; Chemical Evolution of N2H+ in High-Mass Star-Forming Regions
作者: Wen-Tse Chien; 錢玟澤
摘要: 根據觀測，大質量恆星形成區中N2H+之豐度隨演化增加。然而，這與我們目前認知的天文化學不同：隨著溫度上升，固態CO昇華、氣態CO成了N2H+的主要分解物。為了解決此相悖，我們去驗證一假設：核心區域有著更複雜的化學反應；若縮小觀測尺度、包含入化學反應相較單純之周圍物質，則N2H+豐度之演化趨近原本的天文化學預測。
我們使用李遠哲陣列觀測，其束尺度為5.5角分，大的束尺度能包含熱核心與周圍物質。我們觀測了六個目標、分屬演化的三個時期；然而，僅其中四個目標有觀測到訊號，此四者之豐度對演化時期的變化趨勢與我們的預測相同。
另一方面，我們發現使用的觀測策略「固定u-v位置」，造成了明顯的座標偏移與主光束衰減；我們用高斯模型來使束函數最適，並以此修正主光束衰減造成的通量損失，修正量最高達27.1%；此外，重力所造成的YTLA盤面變形，使不同基線有不同的相位誤差，估計基線相位誤差造成15.3%的損失。此外，李遠哲陣列尚有其他未被確認的系統不穩定，造成額外之22.7%誤差。因為系統不穩定與缺乏觀測體，我們在未來仍需更多觀測與目標來確認此趨勢。; Based on several high-resolution observations of high-mass star-forming regions, N2H+ abundance increases throughout the evolution process. The increment contrasts with our lack of understanding of astrochemistry: when the growing young star heats gas temperature, and the CO(solid) evaporates into CO(gas). CO(gas) is the primary destroyer to N2H+. Therefore, we expect the N2H+ abundance to decrease with evolution. To solve the inconsistency, we will test an assumption: the core has more complex reactions than the surrounding. In the core, not only CO destroys N2H+, but also other unknown reactions produce or destroy N2H+. If we zoom out the scale and include the surrounding, which has simpler reactions, we will find that the N2H+ abundance decreases in the early stage’s evolution.
We used Yuan-Tseh Lee Array (YTLA), whose beam size was 5.5 arcmins, to observe the different early stages of high-mass star-forming regions. The larger beam probes the flux from both the warm core and the surrounding material. We observed six sources in three different evolution stages. Only four of them had detection, and their abundance’s variance in stages met our prediction, decreasing abundance with evolution.
On the other hand, we found that our observing strategy, maintaining a fixed u-v pattern, caused the notable pointing offset and the primary beam attenuation. We used a Gaussian model to fit the beam function and corrected the primary beam attenuation. The improvement of our correction for the flux loss is up to 27.1%. Moreover, YTLA’s platform deformation by gravity causes the phase error in baselines. The estimation of the loss by the phase error is 15.3%. Besides, YTLA still had unknown system uncertainties in the measurement. The uncertainties caused an extra 22.7% error. With the system uncertainty and the lack of sources, we need more observations and sources to confirm the trend in the future.2020-01-01T00:00:00Z雙超輕軸子宇宙的微擾演化及功率譜Yi-Hsiung hsu許藝薰http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/799972022-11-23T09:20:18Z2021-01-01T00:00:00Z標題: 雙超輕軸子宇宙的微擾演化及功率譜; Evolution of perturbation and power spectrum in a two-component ultralight axionic universe
作者: Yi-Hsiung hsu; 許藝薰
摘要: 本研究目的在理解雙超輕軸子宇宙的線性微擾演化。我們呈現第一個多軸子宇宙的功率譜計算。其中一個特殊結果為以較輕極端軸子與較重自由粒子所組成的情況。此宇宙組成為高紅移星系的形成提供一個可能的解釋。此外，我們的計算保留了各個微擾的速度資訊。這個資訊可以提供未來模擬一個新的方法來建立起始條件。2021-01-01T00:00:00Z雙星系統與旋轉中子星的重力波背景預測Yu-Chiung Lin林祐群http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/492742021-06-15T11:21:44Z2016-01-01T00:00:00Z標題: 雙星系統與旋轉中子星的重力波背景預測; Gravitational Waves Predicted from Stellar Binaries and Rotating Neutron Stars
作者: Yu-Chiung Lin; 林祐群
摘要: 我們使用 Pablo A. Rosado 的方法來計算來自雙星系統與旋轉中子星的重力波背景的譜函數，並且使用最近得到的模型與宇宙參數。Rosado 的重疊函數能夠顯示出重力波背景的可解析性與連續性。將我們計算出的不可解析背景和連續背景與觀測實驗的遺棄的靈敏度曲線做比較，我們可以得知該觀測實驗能探測到何種目標的重力波，以及是否會受到不可解析訊號的汙染。從我們的結果可以得知地面探測器不會受到來自雙星系統與旋轉中子星的不可解析背景的干擾。; We calculated the gravitational wave background from binary systems and rotating neutron stars using Pablo A. Rosado’s recipes of calculating spectral functions with the latest models and cosmological parameters. The overlap functions in Rosado’s works can characterize the resolvability and continuity of the background. Compare the predicted unresolvable and continuous gravitational wave backgrounds to the sensitivity curves of gravitational wave detectors, we can know from which target the background can be detected by the current and planned detectors, and whether the detector would be contaminate by the unresolvable signals. Our results show that the ground-based detectors are free
from the unresolvable backgrounds both from binary systems and rotating neutron stars.2016-01-01T00:00:00Z