IBS CTPU-CGA 2026 Summer School and Workshop for High Energy Physics, Cosmology and Astrophysics in Korea

27 Jul 2026, 12:00 → 31 Jul 2026, 18:00 Asia/Seoul

Muju Deogyusan Resort

The purpose of this school and workshop is to encourage IBS CTPU-CGA and Korean High Energy Physics, Cosmology and Astrophysics Community to exchange ideas, to promote collaboration, and to discuss recent developments in the fields through review talks, lectures, and general talks.

The list of invited speakers is

Kyungjin Ahn (Choseon U)
Bryce Cyr (MIT)
Myoungwon Jeon (Kyunghee U)
Jae-Young Kim (UNIST)
M. James Jee (Yonsei U)
Changbom Park (KIAS)
Hyunbae Park (IBS CTPU-CGA)
Hyunmi Song (Chungnam Nat'l U)
Masahide Yamaguchi (IBS CTPU-CGA)

and many postdocs and students.

Organizing Committee

Sebastian Bahamonde (IBS CTPU-CGA)
Mohammad Ali Gorji (IBS CTPU-CGA)
Dong-Won Jung (IBS CTPU-CGA)
Hyunbae Park (IBS CTPU-CGA)
Yusuke Yamada (IBS CTPU-CGA)
Masahide Yamaguchi (IBS CTPU-CGA)

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Monday 27 July

16:00 → 18:00 Presentations: Introduction and Ice breaking

18:00 → 20:00 Break: Welcome dinner

Tuesday 28 July

10:00 → 11:00 Presentations: 30+30

Convener: Prof. Dong-Won Jung (IBS CTPU-CGA)

10:00 Why is Lambda the zero?

Speaker: Prof. Masahide Yamaguchi (IBS CTPU-CGA)

10:30 TBA

Speaker: Prof. M. James Jee (Yonsei U)

11:00 → 11:30 Break

11:30 → 12:30 Presentations: 20+20+20

Convener: Dr Yuhang Zhu (IBS CTPU-CGA)

11:30 Hairy Black Holes embedded in Cosmology

Speaker: Dr Georg Trenkler (IBS CTPU-CGA)

11:50 Cosmological implication of cross–correlation between galaxy clustering and 21-cm line intensity mapping

Speaker: Dr Minji Oh (Chosun U)

12:10 Intracluster Globular Clusters as Tracers of Dark Matter and Galaxy Cluster Assembly

Speaker: Dr So-Myoung Park (Chungnam Nat'l U)

12:30 → 14:30 Break: Lunch

14:30 → 15:50 Presentations: 20+20+20+20

Convener: Dr Rinku Maji (IBS CTPU-CGA)

14:30 Direct Collapse Black Hole Formation with Axion-Photon Coupling

Speaker: Dr Hao Jiao (IBS CTPU-CGA)

14:50 Cusps, Cores, and Codes: Dwarf Galaxy Comparisons in AGORA

Speaker: Dr Boon Kiat Oh (KIAS)

15:10 Kinematic Dipole Anisotropy of AllWISE AGNs with Color Selection​: Tension with CMB Dipole

Speaker: Mx Dahee Lee (Chosun U)

15:30 TBA

Speaker: Mx Deokhyeong Lee (UNIST)

16:00 → 16:30 Break

16:30 → 17:50 Presentations: 20+20+20+20

Convener: Dr Qianhang Ding (IBS CTPU-CGA)

16:30 Scale-Dependent Growth of Structure in Quintessence Dark Energy: Sound Speed, Equation of State, and the Matter Power Spectrum

Speaker: Dr Trupti Patiil (KIAS)

16:50 From CPL to Canonical Fields: Constraining Quintessence with the Tomographic AP Test

Speaker: Dr Davari Dolatabadi Zahra (KIAS)

17:10 Understanding Core-Collapse Supernovae through Neutrinos

Speaker: Mx Dong Whee Kim (UNIST)

17:30 Constructing an all-sky group catalog from A-SPEC using a Halo-Based Group Finder

Speaker: Mx Dachan Kim (Chungnam Nat'l U)

17:50 → 20:00 Break: Dinner

Wednesday 29 July

10:00 → 11:00 Presentations: 30+30

Convener: Prof. Nils Albin Nilsson (IBS CTPU-CGA)

10:00 Selected Topics in Cosmology with Galaxies and Large-scale Structures in the Universe

Speaker: Prof. Changbom Park (KIAS)

10:30 UNIST Observational Astrophysics Group: From Black Hole Event Horizons to Galaxies and Multi-Messenger Astronomy

Speaker: Prof. Jae-Young Kim (UNIST)

11:00 → 11:30 Break

11:30 → 12:30 Presentations: 20+20+20

Convener: Dr Pritha Bari (IBS CTPU-CGA)

11:30 Analytical waveform modeling with the post-Newtonian theory

Speaker: Dr Eve Dones

11:50 Constraining the Dark Energy Equation of State with the Extended Alcock–Paczyński test

Speaker: Mx Minseong Kwon (KIAS/SNU)

12:10 TBA

Speaker: Mx Yu-Sik Kim (UNIST)

12:30 → 18:00 Break: Free discussion

18:00 → 20:00 Banquet

Thursday 30 July

10:00 → 11:00 Presentations: 30+30

Convener: Prof. Mohammad Ali Gorji (IBS CTPU-CGA)

10:00 TBA

Speaker: Dr Bryce Cyr (MIT)

10:30 Issues and solutions concerning the surprisingly high brightness of early galaxies discovered by JWST

Speaker: Prof. Myoungwon Jeon (Kyunghee U)

11:00 → 11:30 Break

11:30 → 12:30 Presentations: 20+20+20

Convener: Dr Huiyu Zhu (IBS CTPU-CGA)

11:30 Scalar hair in black holes: From singular to regular solutions and their stability

Speaker: Dr Theodoros Nakas (IBS CTPU-CGA)

11:50 The Warm-Hot Intergalactic Medium under varying Dark Matter and Streaming Velocity

Speaker: Mx Eojin Ryu (Chosun U)

12:10 Searching for the DSNB Amidst Cosmic Noise: The History of Star Formation Imprinted on Neutrinos

Speaker: Mx Sung Bin Gam (UNIST)

12:30 → 14:30 Break: Lunch

14:30 → 16:00 Presentations: 30+20+20+20

Convener: Prof. Sebastian Bahamonde (IBS CTPU-CGA)

14:30 Reconstructing the Matter Distribution of the Nearby Universe from Large Spectroscopic Surveys

Speaker: Prof. Hyunmi Song (Chungnam Nat'l U)

15:00 Listening to the Gravitational-Wave Symphony of Cosmic Strings

Speaker: Dr Ivan Rybak (IBS CTPU-CGA)

15:20 Tracing the Circumgalactic Medium around High-redshift Galaxies with Lya Halos

Speaker: Mx Jaeyeom Geum (Chungnam Nat'l U)

15:40 Probing Small Dark Matter Halos through Milli-Lensing Systems with KVN Observations

While the existence of dark matter is supported by multiple independent cosmological and astrophysical probes, its detailed physical properties remain uncertain. The Search for Milli-LEnses (SMILE) project is an international collaboration that aims to constrain the abundance of dark matter halos in the 10⁶-10⁹ Msun mass range, a hitherto poorly explored regime. The SMILE project approaches this problem through direct VLBI imaging of milliarcsecond-scale lensed images (milli-lenses) of background radio sources. As part of this effort, we conducted KVN observations at 22 and 43 GHz of promising milli-lens candidates selected from the full SMILE sample, with the goal of characterizing their millimeter-wave spectral properties and testing their lensing nature. Through rigorous visibility-domain detection tests, we obtained four secure and five tentative detections among the 17 observed sources. For several of these sources, these observations represent their first reported detections at 22 GHz. These detections enabled us to apply several key diagnostics for gravitational lensing, including surface-brightness conservation, invariance of spectral shape, and flux-ratio stability across epochs. In this talk, we present the details of these results and discuss their implications for current models of dark matter.

Speaker: Mx Mingyu Ryu (UNIST)

16:00 → 16:30 Break

16:30 → 17:30 Presentations: 20+20+20

Convener: Dr Pavel Petrov (IBS CTPU-CGA)

16:30 Turbulent primordial magnetic fields

Speaker: Dr Fumio Uchida (IBS CTPU-CGA)

16:50 TBA

Speaker: Mx Ha Gyeong Cha (UNIST)

17:10 TBA

Speaker: Mx Ho Jun Jeong (UNIST)

17:30 → 19:40 Break: Dinner

Friday 31 July

10:00 → 11:00 Presentations: 30+30

Convener: Prof. Yusuke Yamada (IBS CTPU-CGA)

10:00 CMB-like Properties of the 21cm Background, the 2nd Most Primordial Radiation, and More

Speaker: Prof. Kyungjin Ahn (Chosun U)

10:30 Probing the Reionization Era with Lyα Photons

Speaker: Prof. Hyunbae Park (IBS CTPU-CGA)

11:00 → 11:30 Break

11:30 → 12:30 Presentations: 20+20+20

Convener: Prof. Hyunbae Park (IBS CTPU-CGA)

11:30 Proton capture in compact dark stars and observable implications

Asymmetric dark matter under certain conditions could form compact star-like objects, which can be searched either through gravitational lensing or by observation of gravitational waves from binaries involving such compact objects. In this presentation, we analyze possible signatures of such dark stars made of asymmetric dark matter with a portal to the Standard Model. We argue that compact dark stars could capture protons and electrons from the interstellar medium, which then accumulate in the core of the dark star, forming a very hot gas that emits X-rays or γ-rays. For dark matter parameters compatible with current laboratory constraints, compact dark stars could be sufficiently luminous to be detected at the Earth as point sources in the X-ray or gamma-ray sky.

Speaker: Dr Boris Betancourt Kamenetskaia (IBS CTPU-CGA)

11:50 Cosmological observables on the past light cone

Speaker: Dr Matteo Magi (IBS CTPU-CGA)

12:10 Post-inflationary dynamics of Warm Inflation: Relic Cold Dark Matter from Inflaton Remnant

Warm inflation is usually expected to completely deplete the inflaton condensate by dissipating its energy into radiation. We show that this expectation fails in a simple and observationally viable regime. In a strongly dissipative warm inflationary scenario, the dissipative ratio, $\frac{\Upsilon}{3H}$, can fall rapidly after the end of inflation as the system approaches radiation domination, thereby suppressing further energy transfer to the thermal bath. This leads to a residual inflaton condensate, which subsequently evolves as an effectively non-dissipative scalar field. For potentials with a stable quadratic minimum, this remnant inflaton manifests as a cold dark matter component. We establish this mechanism for the minimal renormalizable potential, with a dissipative coefficient, $\Upsilon \propto T^3$. In this case, current cosmological data allow strong dissipation while leaving the inflaton mass weakly constrained by inflationary observables. The observed dark matter abundance then fixes its mass to be $m \approx 0.02$ MeV, while larger masses overclose the Universe. The transition to matter-like scaling occurs well before BBN, avoiding a long-lived inflaton dark radiation component. Relic inflaton dark matter therefore turns the post-inflationary dynamics of warm inflation into a new late time constraint on its parameter space. The present analysis [https://inspirehep.net/literature/3170948] is phenomenological. Research work including microscopic model building, as well as computing of dark matter isocurvature perturbations, is currently ongoing and will be reported in a future meeting.

Speaker: Dr Swagat Saurav Mishra (IBS CTPU-CGA)

12:30 → 12:40 Adjourn

Convener: Prof. Masahide Yamaguchi (IBS CTPU-CGA)