RESEARCH

Research Units

Study of first-generation objects in the universe with radio telescopes

The 21cm line emission from neutral hydrogen is a key quantity to understand the Epoch of Reionization, where the first stars and galaxies were formed and ionized the intergalactic hydrogen. However, due to the weakness of the signal and the presence of huge foreground, the 21cm line signal has never been detected so far. In this project, we aim to detect the 21cm line signal from the Epoch of Reionization for the first time, using a low-frequency radio interferometer, Murchison Widefield Array (MWA), located in Australia.

In the 100 MHz band, in addition to this signal, there are foreground radiation such as galactic and extragalactic radio objects, and their intensity is much stronger than the signal. Therefore, precise removal of these foreground emissions is critical to signal detection. Therefore, we will develop methods to estimate and remove the spectrum and spatial distribution of foreground radiation using advanced statistical methods such as sparse modeling. Further, avoidance of foreground with cross-correlation between 21cm line signal and galaxies will be pursued using machine learning methods such as artificial neural network.

The MWA is a radio interferometer and the distribution of radio intensity in the sky can be obtained by combining the signal phase differences of all pairs of antennas. However, because the number of antennas is finite, the intensity distribution can not be completely reconstructed. This is a serious problem in observing the size and shape of the ionizing bubbles formed around the first stars. We use sparse modeling techniques to interpolate such missing data and obtain accurate intensity maps.

Research Keyword:
radio astronomy, big data, machine learning, AI

Unit members

  • Japan
    Unit coordinator
    Keitaro TAKAHASHI
    Professor, Faculty of Advanced Science and Technology, Kumamoto University
    Japan
  • Australia
    Rachel WEBSTER
    Professor, The University of Melbourne
    Australia
  • Australia
    Bart PINDOR
    Academic, The University of Melbourne
    Australia
  • Japan
    Shintaro YOSHIURA
    JSPS Researcher, National Astronomical Observatory of Japan
    Japan
  • Japan
    Takuya AKAHORI
    Researcher, National Astronomical Observatory of Japan
    Japan
  • Japan
    Takeshi FUKUSAKO
    Professor, Faculty of Advanced Science and Technology, Kumamoto University
    Japan
  • Japan
    Ryo KATO
    Researcher, Faculty of Advanced Science and Technology, Kumamoto University
    Japan

Achievements

Publications

 “Low-frequency wideband timing of InPTA pulsars observed with the uGMRT”
K Nobleson, Nikita Agarwal, Raghav Girgaonkar, Arul Pandian, Bhal Chandra Joshi, M A Krishnakumar, Abhimanyu Susobhanan, Shantanu Desai, T Prabu, Adarsh Bathula, Timothy T Pennucci, Sarmistha Banik, Manjari Bagchi, Neelam Dhanda Batra, Arpita Choudhary, Subhajit Dandapat, Lankeswar Dey, Yashwant Gupta, Shinnosuke Hisano, Ryo Kato, Divyansh Kharbanda, Tomonosuke Kikunaga, Neel Kolhe, Yogesh Maan, Piyush Marmat, P Arumugam, P K Manoharan, Dhruv Pathak, Jaikhomba Singha, Mayuresh P Surnis, Sai Chaitanya Susarla, Keitaro Takahashi
to be published in Monthly Notices of the Royal Astronomical Society (2022)

“A Parkes "Murriyang" Search for Pulsars and Transients in the Large Magellanic Cloud”
Shinnosuke Hisano, Fronefield Crawford, Victoria Bonidie, Md F. Alam, Keitaro Takahashi, Duncan R. Lorimer, Josh P. Ridley, Maura M. McLaughlin, Benetge B. P. Perera
to be published in Astrophysical Journal (2022)

“Testing the non-circularity of the spacetime around Sagittarius A* with orbiting pulsars”
Yohsuke TAKAMORI, Atsushi NARUKO, Yusuke SAKURAI, Keitaro Takahashi, Daisuke YAMAUCHI, and Chul-Moon Yoo,
 to be published in Astronomical Society of Japan (2022)

“Constraints on ultra-low-frequency gravitational waves from an eccentric supermassive black hole binary”
Tomonosuke Kikunaga, Shinnosuke Hisano, Hiroki Kumamoto, and Keitaro Takahashi,
Monthly Notices of the Royal Astronomical Society, Volume 509, Issue 4, pp.5188-5196, 02/2022

“Axion Cloud Decay due to the Axion-photon Conversion with Background Magnetic Fields”
Yoo, Chul-Moon; Naruko, Atsushi; Sakurai, Yusuke; Takahashi, Keitaro; Takamori, Yohsuke; Yamauchi, Daisuke,
Publications of the Astronomical Society of Japan, Volume 74, Issue 1, pp.64-72, 02/2022

“Epoch of Reionization Power Spectrum Limits from Murchison Widefield Array Data Targeted at EoR1 Field”
M. Rahimi, B. Pindor, J. L. B. Line, N. Barry, C. M. Trott, R. L. Webster, C. H. Jordan, M. Wilensky, S. Yoshiura, A. Beardsley, J. Bowman, R. Byrne, A. Chokshi, B. J. Hazelton, K. Hasegawa, E. Howard, B. Greig, D. Jacobs, R. Joseph, M. Kolopanis, C. Lynch, B. McKinley, D. A. Mitchell, S. Murray, M. F. Morales, J. C. Pober, K. Takahashi, S. J. Tingay, R. B. Wayth, J. S. B. Wyithe, Q. Zheng,
Monthly Notices of the Royal Astronomical Society, Volume 508, Issue 4, pp.5954-5971, 12/2021

 “Constraining the 21cm brightness temperature of the IGM at z=6.6 around LAEs with the Murchison Widefield Array”
Cathryn M. Trott, C.H. Jordan, J.L.B. Line, C.R. Lynch, S. Yoshiura, B. McKinley, P. Dayal, B. Pindor, A. Hutter, K. Takahashi, R.B. Wayth, N. Barry, A. Beardsley, J. Bowman, R. Byrne, A. Chokshi, B. Greig, K. Hasegawa, B.J. Hazelton, E. Howard, D. Jacobs, M. Kolopanis, D.A. Mitchell, M.F. Morales, S. Murray, J.C. Pober, M. Rahimi, S.J. Tingay, R.L. Webster, M. Wilensky, J.S.B. Wyithe, Q. Zheng,
Monthly Notices of the Royal Astronomical Society Letters 507 (2021) 772-780, 10/2021

“Evidence for profile changes in PSR J1713+0747 using the uGMRT”
Jaikhomba Singha, Mayuresh P Surnis, Bhal Chandra Joshi, Pratik Tarafdar, Prerna Rana, Abhimanyu Susobhanan, Raghav Girgaonkar, Neel Kolhe, Nikita Agarwal, Shantanu Desai, T Prabu, Adarsh Bathula, Subhajit Dandapat, Lankeswar Dey, Shinnosuke Hisano, Ryo Kato, Divyansh Kharbanda, Tomonosuke Kikunaga, Piyush Marmat, Sai Chaitanya Susarla, Manjari Bagchi, Neelam Dhanda Batra, Arpita Choudhury, A Gopakumar, Yashwant Gupta, M A Krishnakumar, Yogesh Maan, P K Manoharan, K Nobleson, Arul Pandian, Dhruv Pathak, Keitaro Takahashi,
Monthly Notices of the Royal Astronomical Society Letters 507 (2021) L57-L61, 10/2021

“Predicting 21cm-line map from Lyman α emitter distribution with Generative Adversarial Networks”
Shintaro Yoshiura, Hayato Shimabukuro, Kenji Hasegawa, Keitaro Takahashi,
Monthly Notices of the Royal Astronomical Society 506 (2021) 357-371, 09/2021

“A new MWA limit on the 21 cm Power Spectrum at Redshifts ∼ 13 – 17"
S. Yoshiura, B. Pindor, J.L.B. Line, N. Barry, C. M. Trott, A. Beardsley, J. Bowman, R. Byrne, A. Chokshi, B. J. Hazelton, K. Hasegawa, E. Howard, B. Greig, D. Jacobs, C. H. Jordan, R. Joseph, M. Kolopanis, C. Lynch, B. McKinley, D. A. Mitchell, M. F. Morales, S. Murray, J. C. Pober, M. Rahimi, K. Takahashi, S. J. Tingay, R. B. Wayth, R. L. Webster, M. Wilensky, J. S. B. Wyithe, Z. Zhang, Q. Zheng,
Monthly Notices of the Royal Astronomical Society 505 (2021) 4775-4790, 08/2021

 “Constraints on ultra-low-frequency gravitational waves with statistics of pulsar spin-down rates II: Mann-Whitney U test”
Kumamoto, H.; Hisano, S.; Takahashi, K.,
PASJ 73 (2021) 1001, 08/2021

H. Kumamoto, S. Dai, S. Johnston, M. Kerr, R. M. Shannon, P. Weltevrede, C. Sobey, R. N. Manchester, G. Hobbs, and K. Takahashi,
“Flux density variability of 286 radio pulsars from a decade of monitoring”
Monthly Notices of the Royal Astronomical Society 501 (2021) 4490-4513, 03/2021

N. Yonemaru, S. Kuroyanagi, G. Hobbs, K. Takahashi, X.-J. Zhu, W. A. Coles, S. Dai, E. Howard, R. Manchester, D. Reardon, C. Russell, R. Shannon, N. Thyagarajan, R. Spiewak, J.-B. Wang,
“Searching for gravitational wave bursts from cosmic string cusps with the Parkes Pulsar Timing Array”
Monthly Notices of the Royal Astronomical Society 501 (2021) 701-712, 02/2021

Suchetha Cooray, Tsutomu T. Takeuchi, Takuya Akahori, Yoshimitsu Miyashita, Shinsuke Ideguchi, Keitaro Takahashi and Kiyotomo Ichiki,
“An Iterative Reconstruction Algorithm for Faraday Tomography”
Monthly Notices of the Royal Astronomical Society 500 (2021) 5129-5141, 01/2021

Zhang, Zheng; Pober, Jonathan C.; Li, Wenyang; Hazelton, Bryna J.; Morales, Miguel F.; Trott, Cathryn M.; Jordan, Christopher H.; Joseph, Ronniy C.; Beardsley, Adam; Barry, Nichole; Byrne, Ruby; Tingay, Steven J.; Chokshi, Aman; Hasegawa, Kenji; Jacobs, Daniel C.; Lanman, Adam; Line, Jack L. B.; Lynch, Christene; McKinley, Benjamin; Mitchell, Daniel A. Murray, Steven; Pindor, Bart; Rahimi, Mahsa; Takahashi, Keitaro; Wayth, Randall B.; Webster, Rachel L.; Wilensky, Michael; Yoshiura, Shintaro; Zheng, Qian,
“The Impact of Tandem Redundant/Sky-Based Calibration in MWA Phase II Data Analysis”
Publications of the Astronomical Society of Australia 37 (2020) article id. e045, 11/2020

Yoshiura, Shintaro; Oguri, Masamune; Takahashi, Keitaro; Takahashi, Tomo,
“Constraints on Primordial Power Spectrum from Galaxy Luminosity Functions”
Phys. Rev. D 102 (2020) 083515, 10/2020

Haruya Eguchi, Masaki Suzuki, Yoshimitsu Miyashita, Shinsuke Ideguchi, Keitaro Takahashi,
“Faraday dispersion function of disk galaxies with axisymmetric global magnetic fields I”
Astrophys. J. 899 (2020) id.122, 08/2020

Yuta Shiohira, Yuka Terada, Den Mukuno, Yuka Fujii, Keitaro Takahashi,
“Microlensed Radio Emission from Exoplanets”
Monthly Notices of the Royal Astronomical Society 495 (2020) 1934-1942, 05/2020

Yoshiura, Shintaro; Takahashi, Keitaro; Takahashi, Tomo,
“Probing Small Scale Primordial Power Spectrum with 21cm Line Global Signal”
Phys. Rev. D 101 (2020) 083520, 04/2020

Kenji Kubota, Akio. K. Inoue, Kenji Hasegawa, Keitaro Takahashi,
“Detectability of 21cm signal during the Epoch of Reionization with 21cm-Lyman-α emitter cross-correlation. III. Model dependence”
Monthly Notices of the Royal Astronomical Society 494 (2020) 3131?3140, 04/2020

Naoyuki Yonemaru, Keitaro Takahashi, Hiroki Kumamoto, Shi Dai, Shintaro Yoshiura and Shinsuke Ideguchi,
“Artificial neural networks for selection of pulsar candidates from the radio continuum surveys”
Monthly Notices of the Royal Astronomical Society 494 (2020) 1035?1044, 04/2020

Grants

Kiban B (rep: Keitaro Takahashi), accepted (2021-2024)
Kiban A (rep: Naoshi Sugiyama (Nagoya University)), accepted (2021-2025)

Activities

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