Welcome to AXIS,

Astrophysics Lab at Chung-Ang University.

๐Ÿ‘‹ ์•ˆ๋…•ํ•˜์„ธ์š”, ์ค‘์•™๋Œ€ํ•™๊ต ์ฒœ์ฒด๋ฌผ๋ฆฌ์—ฐ๊ตฌ์‹ค์ž…๋‹ˆ๋‹ค.

Group Meeting

  • Friday, 16:30-17:30
  • Room. 203, Building # 209

Publication

  • Leigh Smith, Sayantan Ghosh, Jiyoon Sun, V. Gayathri, Ik Siong Heng, and Archana Pai, "Enhancing search pipelines for short gravitational-wave transients with Gaussian mixture modeling," Phys. Rev. D 110, 083032 (2024) [DOI]
  • Yeong-Bok Bae, Young-Hwan Hyun, and Gungwon Kang, "Ringdown Gravitational Waves from Close Scattering of Two Black Holes," Phys. Rev. Lett. 132, 261401 (2024) [DOI]

Research

์šฐ๋ฆฌ๋Š” ์ด๋Ÿฐ ์—ฐ๊ตฌ๋ฅผ ํ•˜๊ณ  ์žˆ์–ด์š”.

Gravitational Waves

Gravitational waves will bring us exquisitely accurate maps of black holes - maps of their space-time. Those maps will make it crystal clear whether or not what were dealing with are black holes as described by general relativity.

Kip S. Thorne
Gravitational waves serve as carriers of invaluable information regarding the motion of celestial bodies in the Universe. Unlike electromagnetic waves, gravitational waves are neither absorbed nor reflected by cosmic matter, thereby providing an unobstructed view of their original form. Consequently, gravitational waves hold the potential for discovering the unknown.

Burst signals encompass transient gravitational wave signals of short duration, typically lasting less than a second. While it is established that phenomena such as supernovae, gamma-ray bursts, or highly eccentric binary mergers may serve as potential progenitors of burst gravitational waves, our understanding of these complex systems remains incomplete, rendering waveform predictions uncertain or too intricate for a template-based search. Moreover, gravitational wave detectors are becoming more sensitive, leading to heightened sensitivity to spurious signals or "glitches," necessitating the development of additional methods for glitch rejection to enhance search sensitivity.

Within the AXIS laboratory, our research is centered on the coherent detection and reconstruction of burst signals by utilizing a network of detectors, particularly in cases where theoretical predictions for signal waveforms are lacking. Additionally, we employ Gaussian Mixture Modeling(GMM) to enhance the search sensitivity, allowing us to differentiate true gravitational wave signals from glitches.

Numerical Relativity

Motivated by the forthcoming observations of ground-based gravitational wave detectors, such as the LIGO and by the next generation of space-based detectors, such as the LISA, the numerical relativity community has dedicated a great deal of effort to solving the binary-black-hole problem over the last few decades.

M. Campanelli
The general theory of relativity, introduced by Einstein in 1915, allows us to predict the dynamics of various celestial bodies, such as black holes and neutron stars, as well as the emission of gravitational waves. When dealing with systems of low compactness or low orbital velocities, we can calculate the required physical quantities using approximations like post-Minkowskian or post-Newtonian methods. However, in extreme situations where approximations become unreliable, such as during the merger of binary black hole systems, we must solve Einstein's field equations without approximation. Since Einstein's field equations are nonlinear partial differential equations, finding analytical solutions for general cases is challenging.

To tackle these complex equations, various methods have been developed, leading to the advancement of numerical relativity. We primarily use the Einstein Toolkit to simulate a wide range of high-energy astrophysical phenomena. The Einstein Toolkit is based on Cactus and employs computational algorithms like Finite Difference Method (FDM), Spectral Method, and Adaptive Mesh Refinement (AMR) to ensure accurate and sophisticated results. We model specific scenarios of interest to calculate energy changes, gravitational wave emissions, and other relevant quantities.

The calculated gravitational waveforms play a crucial role in gravitational wave detection. To successfully detect gravitational waves, we must demonstrate a strong cross-correlation with precomputed waveforms, which necessitates high-precision waveform calculations. We perform convergence tests and validate the simulation's accuracy by comparing results in the weak field regime with post-Newtonian approximations.

Furthermore, we are committed to improving existing numerical algorithms and developing more efficient code to enhance performance.

Members

Prof. Gungwon Kang

  • Professor, Department of Physics, Chung-Ang University (2022.2 โ€“ present)
  • Office : 209-201
  • Email : gwkangalternate_emailcau.ac.kr
  • Publication : Google Scholar

Dr. Yeong-Bok Bae

  • Research professor
  • Astrophysics, Numerical Relativity, Gravitational Waves
  • Email : baeybalternate_emailcau.ac.kr

Dr. Young-Hwan Hyun

  • Associate Researcher
  • Study of strong gravity phenomena through Black Holes and Gravitational Waves
  • Email : younghwan.hyunalternate_emailgmail.com

Jiyoon Sun

  • M.S. Student
  • Gravitational Waves
  • Email : giojeeunalternate_emailcau.ac.kr

Hyeonguk Son

  • M.S. Student
  • TBA
  • Email : matthewson128alternate_emailgmail.com

Dongchan Kim

  • M.S. Student
  • Numerical Relativity
  • Email : krq3268alternate_emailcau.ac.kr

Yejun Han

  • Intern
  • TBA
  • Email : hanyejun1106alternate_emailcau.ac.kr

Contact

  • Room. 203, Building # 209, Chung-Ang University, Seoul 06974, Korea.

    • Join group

    • For Postdocs, Graduate students, Undergraduate students
    • Please email to Prof. Kang. (gwkangalternate_emailcau.ac.kr)