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Searching for Non-standard Physics in Cosmic Microwave Background.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Searching for Non-standard Physics in Cosmic Microwave Background./
作者:	Yeung, Shek.
面頁冊數:	1 online resource (152 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
Contained By:	Dissertations Abstracts International84-01B.
標題:	Astrophysics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29282524click for full text (PQDT)
ISBN:	9798802756683

Searching for Non-standard Physics in Cosmic Microwave Background.
Yeung, Shek.

Searching for Non-standard Physics in Cosmic Microwave Background. - 1 online resource (152 pages)

Source: Dissertations Abstracts International, Volume: 84-01, Section: B.

Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2022.

Includes bibliographical references

The Cosmic Microwave Background (CMB) has been measured very precisely. This allows us to constrain many different cosmological models. The ΛCDM model is regarded as the "standard model" in cosmology. However, the 4.0σ tension on the Hubble parameter H0 between the Planck CMB and other local measurements raises the possibility of new physics beyond ΛCDM.In the first study, we consider the impact of a finite relic neutrino degeneracy ξν, which requires no extension beyond the Standard Model of particle physics, on the CMB angular power spectra, and study the correlations between ξν, H0, and the spectral index ns. We demonstrate that, with a non-zero ξν, the tension on H0 is alleviated and constraints on inflation models are loosened significantly. Our results suggest that ξν is a nonnegligible physical parameter for cosmological analyses.In the second study, we consider the possibilities of directional variation of the cosmological parameters. We fit the Planck temperature angular power spectrum CTTl for 48 different half-skies, centering on 48 different directions, to search for directional dependences of the standard cosmological parameters. There are 3[2]σ-level directional variations in Ωbh 2, Ωch 2, i ns, 100θMC, and H0 [τ and ln(1010As)]. The directional distributions of the parameters follow a dipole form to good approximation. The Bayes factor between the isotropic and anisotropic hypotheses is 0.0041, strongly disfavouring the former. The best-fit dipole axes for Ωbh2, Ωch2, ns, 100θMC, and Ase-2τ all generally align with the mean direction of V ≡ (l = 48.8°+14.3°-14.4°, b = −5.6°+17.0° -17.4°°), which is roughly perpendicular to the dipole of the variation in fine structure constant, and is about 45° to the directions of the CMB kinematic dipole, CMB parity asymmetry, and polarization of QSOs. Our results suggest either significant violation of the cosmological principle, or previously unknown systematic errors in the standard CMB analysis.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798802756683Subjects--Topical Terms:

535904
Astrophysics.
Subjects--Index Terms:

Non-standard physicsIndex Terms--Genre/Form:

542853
Electronic books.

Searching for Non-standard Physics in Cosmic Microwave Background.
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500 $a Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
500 $a Advisor: Law, Chi Kwong; Chu, Ming Chung.
502 $a Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2022.
504 $a Includes bibliographical references
520 $a The Cosmic Microwave Background (CMB) has been measured very precisely. This allows us to constrain many different cosmological models. The ΛCDM model is regarded as the "standard model" in cosmology. However, the 4.0σ tension on the Hubble parameter H0 between the Planck CMB and other local measurements raises the possibility of new physics beyond ΛCDM.In the first study, we consider the impact of a finite relic neutrino degeneracy ξν, which requires no extension beyond the Standard Model of particle physics, on the CMB angular power spectra, and study the correlations between ξν, H0, and the spectral index ns. We demonstrate that, with a non-zero ξν, the tension on H0 is alleviated and constraints on inflation models are loosened significantly. Our results suggest that ξν is a nonnegligible physical parameter for cosmological analyses.In the second study, we consider the possibilities of directional variation of the cosmological parameters. We fit the Planck temperature angular power spectrum CTTl for 48 different half-skies, centering on 48 different directions, to search for directional dependences of the standard cosmological parameters. There are 3[2]σ-level directional variations in Ωbh 2, Ωch 2, i ns, 100θMC, and H0 [τ and ln(1010As)]. The directional distributions of the parameters follow a dipole form to good approximation. The Bayes factor between the isotropic and anisotropic hypotheses is 0.0041, strongly disfavouring the former. The best-fit dipole axes for Ωbh2, Ωch2, ns, 100θMC, and Ase-2τ all generally align with the mean direction of V ≡ (l = 48.8°+14.3°-14.4°, b = −5.6°+17.0° -17.4°°), which is roughly perpendicular to the dipole of the variation in fine structure constant, and is about 45° to the directions of the CMB kinematic dipole, CMB parity asymmetry, and polarization of QSOs. Our results suggest either significant violation of the cosmological principle, or previously unknown systematic errors in the standard CMB analysis.
520 $a 我們可以利用精確測量的微波背景輻射 (CMB) 來約束各種不同的宇宙模型。雖然 ΛCDM 模型被稱為宇宙學的『標準模型』，但是這個模型和一些觀測數據有很大差異。例如 Planck 的 CMB 和其他鄰近天文觀測得出的哈勃參數 H0 相差四個標準差，而這表示可能存在 ΛCDM 模型以外的新物理。在第一個研究，我們考慮在粒子物理標準模型容許為非零的中微子簡併參數 ξν 對 CMB 各向異性角功率譜的影響和 ξν 與 H0 及譜指數 ns 之間的相關性。我們發現在 ΛCDM 模型加入 ξν 可以減輕 H0 的差異，而且也會放鬆宇宙暴脹理論的約束。這些結果意味着 ξν 在宇宙論模型中是不可忽略的參數。在第二個研究，我們探究宇宙參數各向異性的可能性。我們使用 48 個不同方向的半天球 CMB 數據來作出參數推論，從而找出宇宙參數是否根據方向變化。我們發現不用方向之間推論的參數最大差異可達兩個標準差，而各個參數的方向分佈大約為偶極。參數各向同性和各向異性的假設之間的貝葉斯因子是 0.0041，表示有非常強的證據支持後者。Ωbh 2、Ωch 2、 ns、100θMC 和 Ase −2τ 的最佳擬合偶極軸平均方向為 V ≡ (l = 48.8°+14.3°−14.4°, b = −5.6°+17.0°−17.4° °)，大致垂直於精細結構常數變化的偶極，而與 CMB 運動偶極、CMB 宇稱非對稱和類星體極化的方向的夾角大概為 45°。這些結果意味着 CMB 數據違反了宇宙論原則或者在分析 CMB 數據時存在未知的系統誤差。
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Astrophysics. $3 535904
650 4 $a Physics. $3 516296
650 4 $a Astronomy. $3 517668
653 $a Non-standard physics
653 $a Cosmic Microwave Background
653 $a Cosmology
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0596
690 $a 0606
690 $a 0605
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a The Chinese University of Hong Kong (Hong Kong). $3 1017547
773 0 $t Dissertations Abstracts International $g 84-01B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29282524 $z click for full text (PQDT)