Welcome and Introduction to CHiP

• Yung-Fu Chen (NCU)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Introduction to GW-CMB workshop

• Masashi Hazumi (National Central University)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Simons Observatory and Primordial Gravitational Waves

• Yuji Chinone (KEK)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂 The cosmic microwave background (CMB) remains one of the most powerful probes of the early universe, providing insights into its composition, geometry, and evolution. While early studies focused on temperature anisotropies, the next frontier lies in precise measurements of CMB polarization. In particular, detecting the curl-like B-mode pattern would provide compelling evidence for primordial gravitational waves generated during inflation, offering a unique window into physics at energy scales far beyond terrestrial experiments. This talk will begin with an overview of CMB observations and their role in cosmology, then highlight key results from the POLARBEAR experiment, which pioneered polarization measurements and set important constraints on B-mode signals. Building on these achievements, I will introduce the Simons Observatory—a next-generation ground-based experiment—and discuss its strategy to improve sensitivity, tackle systematic challenges, and advance the search for primordial B-modes. In addition, I will touch on how polarization observations can probe new physics, including axion-like particles through cosmic birefringence, illustrating the synergy between cosmology and fundamental physics.

GW Landscape

• Yuki Inoue (National Central University)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Photos Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

A search for Planet 9

• Tomo Goto (NTHU)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Dark matter vs. baryons beyond equilibrium

• Keiichi Umetsu (ASIAA)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Dynamical Dark Energy and neutrino masses circa 2025

• Shouvik Roy Choudhury (ASIAA)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Constraints on amplitude and tilt of the tensor primordial spectrum

• Giacomo Galloni (Univ. of Ferrara)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Science with Simons Observatory Large Aperture Telescope

• Colin Hill (Columbia Univ.)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

A Journey through the Full CMB–LSS Tomography: From Milky Way Dust, tSZ, and CIB to CO and [CII] Lines

• Yi-Kuan Chiang (ASIAA)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂 CMB data are maximally projected along the line of sight, with intricate secondary anisotropies that each reveal a distinct chapter of cosmic evolution. In a series of six papers and ongoing, we embark on a deeply data-intensive, cross-correlation redshift tomography of CMB data, analyzing over two billion HEALPix pixels across more than twenty diffuse sky maps (e.g., Planck, IRAS, Herschel) together with LSS tracers from galaxy surveys with available spectroscopic redshifts pre-DESI. This unified campaign unlocks a panoramic view of cosmic baryons across space and time. Key results include: (1) a measurement of the cosmic thermal energy history, $\Omega_{\rm th}$, in hot gas and its implications for structure growth powered by gravitational energy, $\Omega_{\rm grav}$; (2) the most precise cosmic star-formation history to date, revealed by 11-band CIB tomography with fully constrained SEDs; (3) the cosmic dust evolution, $\Omega_{\rm dust}$, across all host environments; (4) the identification and removal of CIB leakage in ten Galactic dust maps, yielding a field-level component-separation algorithm as a constrained realization of 3D LSS data and producing the “CSFD” dust map; and, in the latest installment of the series, (5) the first tomographic detection of CO and [CII] line-intensity backgrounds, tracing the molecular-gas density, $\Omega_{\rm H_2}$, and the cosmic cooling budget over 12 Gyr of history.

Extracting parity-violating gravitational waves from the large-scale structure of the universe

• Teppei Okumura (ASIAA)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Universal redshifted black hole quasinormal modes induced by environments

• Che-Yu Chen (RIKEN)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂 The ringdown phase of gravitational waves emitted by a perturbed black hole is described by a superposition of exponentially decaying sinusoidal modes, called quasinormal modes (QNMs), whose spectra depend only on the property of the black-hole geometry. The extraction of QNM frequencies of an isolated black hole thus allows for testing GR, the so-called black hole spectroscopy program. However, astrophysical black holes are not perfectly isolated. It remains unclear whether the validity of black hole spectroscopy would be affected when environmental effects surrounding the black holes are taken into account, such as accretion disk, dark matter halo, etc. In this talk, by taking a black hole surrounded by a gravitating thin disk as an example, we show that there seems to be a universal redshift relation for QNM spectrum in the presence of such environmental effects. The implications on testing GR through black hole spectroscopy will be discussed.

New Results from LIGO

• Daiki Tanabe (ASIoP)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂

Monodromy Approach to Quasi-Normal Modes of Black Holes

• Viona Wei (NCU)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂 The quasi-normal modes (QNMs) are the oscillation modes of black holes. This kind of mode will be interesting when we study the ringdown of gravitational waves. In theoretical conception, the highly damped frequencies of QNMs would show quantum phenomena such as Bohr’s hydrogen atom model. One of the analyzing methods is called “Monodromy” which is more precise to solve the highly damped frequencies of QNMs.

Circular Polarization and Doppler-Induced Dipole Anisotropies in the Stochastic Gravitational-Wave Background

• Sevgi Karadağ (ASIoP)

Room: 國立中央大學 教学研究総合大楼 羅家倫講堂 Some inflationary models predict a circularly polarized stochastic gravitational-wave background (SGWB) with potential cosmological significance. We develop a simulation and parameter-estimation framework to characterize circular polarization and Doppler-induced dipole anisotropies in the SGWB. The pipeline jointly constrains the polarization degree (Π), energy density (Ω_GW), and dipole amplitude (D_α), validated through simulated signals and applied to LIGO O1–O3 data. We derive upper limits on Π, Ω_GW, and D_α.

Final discussion Room: 國立中央大學 教学研究総合大楼 羅家倫講堂