Explanipedia

Origin and Evolution of the $Ω$ Structure in the Head-Tail Radio Galaxy of Abell 3322 Open

Kohei Kurahara, Takuya Akahori, Takumi Ohmura, Shintaro Yoshiura, Daisuke Ito , et al. · 2025

A head-tail galaxy is thought to be a radio galaxy with bent active galactic nuclei (AGN) jets interacting with the intracluster medium (ICM). Study of head-tail galaxies provides us with fruitful insights into the mechanisms of shock wave…

Three-dimensional Polarimetric Structure of Jets from Radio Galaxy MRC 0600–399 in A3376 Open

Haruka Sakemi, James O. Chibueze, W. D. Cotton, Viral Parekh, Takumi Ohmura , et al. · 2025

MRC 0600–399, in the merging galaxy cluster A3376, is one of the unique head–tail radio galaxies that have abruptly bending structures, the origin of which is still under discussion. A previous study suggested that the interaction between …

Square Kilometre Array Science Data Challenge 3a: foreground removal for an EoR experiment Open

Anna Bonaldi, Philippa Hartley, Robert D. Braun, S. J. D. Purser, Anshuman Acharya , et al. · 2025

We present and analyse the results of the Science Data Challenge 3a (SDC3a, https://sdc3.skao.int/challenges/foregrounds), an epoch of reionization (EoR) foreground-removal exercise organized by the Square Kilometre Array Observatory (SKAO…

Three-Dimensional Polarimetric Structure of Jets from Radio Galaxy MRC 0600-399 in A3376 Open

Haruka Sakemi, James O. Chibueze, W. D. Cotton, Viral Parekh, Takumi Ohmura , et al. · 2025

MRC 0600-399, in the merging galaxy cluster Abell 3376, is one of the unique Head-Tail radio galaxies having abruptly bending structures, the origin of which is still under discussion. A previous study suggested that the interaction betwee…

A new window into the sub-parsec scale magnetic field in the Milky Way? Unveiling small-scale magneto-ionic structures with Faraday complexity Open

Yik Ki, Amit Seta, N. M. McClure‐Griffiths, Cameron L. Van Eck, Sui Ann Mao , et al. · 2025

Radio broad-band spectro-polarimetric observations are sensitive to the spatial fluctuations of the Faraday depth (FD) within the telescope beam. Such FD fluctuations are referred to as ‘Faraday complexity’, and can unveil small-scale magn…

Relighting the fire in Hickson Compact Group (HCG) 15: Magnetised fossil plasma revealed by the SKA Pathfinders and Precursors Open

C. J. Riseley, Tessa Vernstrom, L. Lovisari, E. O'Sullivan, F. Gastaldello , et al. · 2025

In the context of the life cycle and evolution of active galactic nuclei (AGNs), environment plays a key role. In particular, the over-dense environments of galaxy groups, where dynamical interactions and bulk motions have significant impa…

The Polarisation Sky Survey of the Universe’s Magnetism (POSSUM): Science goals and survey description Open

B. M. Gaensler, G. Heald, N. M. McClure‐Griffiths, C. S. Anderson, Cameron L. Van Eck , et al. · 2025

The Australian SKA Pathfinder (ASKAP) offers powerful new capabilities for studying the polarised and magnetised Universe at radio wavelengths. In this paper, we introduce the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM), a…

ALMA Observations of the Gamma-Ray Binary System PSR B1259-63/LS 2883 during the 2024 Periastron Passage Open

Yutaka Fujita, A. Kawachi, Atsuo T. Okazaki, Hiroshi Nagai, Norita Kawanaka , et al. · 2024

We present observations of the gamma-ray binary PSR B1259-63/LS 2883 with the Atacama Large Millimeter/submillimeter Array (ALMA) at Band 3 (97 GHz), Band 6 (233 GHz), and Band 7 (343 GHz). PSR B1259-63/LS 2883 consists of a pulsar in a hi…

ALMA observations of the gamma-ray binary system PSR B1259-63/LS 2883 during the 2024 periastron passage Open

Yutaka Fujita, A. Kawachi, Atsuo T. Okazaki, Hiroshi Nagai, Norita Kawanaka , et al. · 2024

We present observations of the gamma-ray binary PSR B1259-63/LS 2883 with the Atacama Large Millimeter/submillimeter Array (ALMA) at Bands 3 (97 GHz), 6 (233 GHz), and 7 (343 GHz). PSR B1259-63/LS 2883 consists of a pulsar in a highly ecce…

Magnetized H <span>i</span> superbubbles in the Small Magellanic Cloud revealed by the POSSUM pilot survey Open

S Lyla Jung, Amit Seta, J. Price, N. M. McClure‐Griffiths, J. D. Livingston , et al. · 2024

Neutral hydrogen (H i) bubbles and shells are common in the interstellar medium (ISM). Studying their properties provides insight into the characteristics of the local ISM as well as the galaxy in which the bubbles reside. We report the de…

Magnetised HI superbubbles in the Small Magellanic Cloud revealed by the POSSUM pilot survey Open

Seoyoung Lyla Jung, Amit Seta, J. Price, N. M. McClure‐Griffiths, J. D. Livingston , et al. · 2024

Neutral hydrogen (HI) bubbles and shells are common in the interstellar medium (ISM). Studying their properties provides insight into the characteristics of the local ISM as well as the galaxy in which the bubbles reside. We report the det…

Probing the magnetized gas distribution in galaxy groups and the cosmic web with POSSUM Faraday rotation measures Open

C. S. Anderson, N. M. McClure‐Griffiths, L. Rudnick, B. M. Gaensler, S. P. O’Sullivan , et al. · 2024

We present initial results from the Polarization Sky Survey of the Universe’s Magnetism (POSSUM), analysing 22 817 Faraday rotation measures (RMs) with median uncertainties of 1.2 rad m$^{-2}$ across 1520 deg2 to study magnetized gas assoc…

The Japanese vision for the Black Hole Explorer mission Open

Kazunori Akiyama, Kotaro Niinuma, Kazuhiro Hada, Akihiro Doi, Yoshiaki Hagiwara , et al. · 2024

Akiyama, Kazunori et al.-- Full list of authors: Akiyama, Kazunori; Niinuma, Kotaro; Hada, Kazuhiro; Doi, Akihiro; Hagiwara, Yoshiaki; Higuchi, Aya E.; Honma, Mareki; Kawashima, Tomohisa; Kolev, Dimitar; Koyama, Shoko; Masui, Sho; Ohsuga, …

Probing the Magnetised Gas Distribution in Galaxy Groups and the Cosmic Web with POSSUM Faraday Rotation Measures Open

C. S. Anderson, N. M. McClure‐Griffiths, L. Rudnick, B. M. Gaensler, S. P. O’Sullivan , et al. · 2024

We present initial results from the Polarisation Sky Survey of the Universe's Magnetism (POSSUM), analysing 22,817 Faraday Rotation Measures (RMs) with median uncertainties of 1.2 rad m^-2 across 1,520 square degrees to study magnetised ga…

Indications of an offset merger in Abell 3667 Open

Yuki Omiya, K. Nakazawa, Tadamasa Tamura, H. Akamatsu, Kyoko Matsushita , et al. · 2024

Context. Cluster mergers are the most energetic events, releasing kinetic energies of up to 10 64 erg and involving megaparsec(Mpc)-scale shocks in their intra-cluster medium (ICM). In merging clusters, cold fronts are frequently observed,…

Indications of an offset merger in Abell 3667 Open

Yuki Omiya, K. Nakazawa, Tadamasa Tamura, H. Akamatsu, Kyoko Matsushita , et al. · 2024

Abell 3667 is a nearby merging cluster with a prominent cold front and a pair of two bright radio relics. Assuming a head-on merger, the origin of the cold front is often considered to be a remnant of the cluster core stripped by its surro…

Discovery of Diffuse Radio Source in Abell 1060 Open

Kohei Kurahara, Takuya Akahori, Aika Oki, Yuki Omiya, K. Nakazawa · 2023

Non-thermal components in the intra-cluster medium (ICM) such as turbulence, magnetic field, and cosmic rays imprint the past and current energetic activities of jets from active galactic neuclie (AGN) of member galaxies as well as disturb…

Galaxy clusters at z ∼ 1 imaged by ALMA with the Sunyaev–Zel’dovich effect Open

Tetsu Kitayama, Shutaro Ueda, N. Okabe, Takuya Akahori, Matt Hilton , et al. · 2023

We present high angular resolution measurements of the thermal Sunyaev–Zel’dovich effect (SZE) toward two galaxy clusters, RCS J2319+0038 at $z$ = 0.9 and HSC J0947−0119 at $z$ = 1.1, by the Atacama Large Millimeter/submillimeter Array (AL…

Tomographic analysis of gravitational lens galaxies with cm-wavelength polarimetry Open

Rikuto Omae, Takuya Akahori, Mami Machida · 2023

Galactic magnetic fields play important roles in various astrophysical processes, yet the cosmological evolution of galactic magnetic fields is largely unknown.To unveil the evolution, observing magnetic fields of distant galaxies is essen…

The Evolution of Galaxies with the Square Kilometre Array Open

Tsutomu T. Takeuchi, Takuya Akahori · 2023

Galaxies have been formed from a homogeneous neutral gas in the early Universe, and evolved with forming stars from the gas in them.Then the key factor of the galaxy formation and evolution is the transition from atomic to molecular hydrog…

Development for Japan L-band VLBI Observation Open

Kohei Kurahara, Takuya Akahori, Kazuhiro Hada, Tomoya Hirota, Sota Ikebe , et al. · 2023

UHF Band RFI Measurements at VERA Four Stations in Japan Open

Takuya Akahori, Sota Ikebe, T. Terasawa, Mareki Honma · 2023

The ultrahigh frequency (UHF, 300 MHz -3 GHz) band is the optimum frequency to explore magnetic field in the intergalactic medium using Faraday tomography [1].Moreover, the UHF band is a promising band for exploring fast radio bursts [2], …

Observing the HSC SXDS field with the uGMRT Band-2 Open

Shintaro Yoshiura, Kohei Kurahara, Takuya Akahori, Keitaro Takahashi · 2023

Diffuse radio source candidate in CIZA J1358.9−4750 Open

Kohei Kurahara, Takuya Akahori, Ruta Kale, Hiroki Akamatsu, Yutaka Fujita , et al. · 2022

We report on results of our upgraded Giant Metrewave Radio Telescope (uGMRT) observations for an early-stage merging galaxy cluster, CIZA J1358.9−4750 (CIZA1359), in Band-3 (300–500 MHz). We achieved the image dynamic range of ∼38000 using…

Detection of a bright burst from the repeating FRB 20201124A at 2 GHz Open

Sota Ikebe, Kazuhiro Takefuji, T. Terasawa, Sujin Eie, Takuya Akahori , et al. · 2022

We present a detection of a bright burst from FRB 20201124A, which is one of the most active repeating FRBs, based on S-band observations with the 64-m radio telescope at the Usuda Deep Space Center/JAXA. This is the first FRB observed by …

Sciences with Thai National Radio Telescope Open

Phrudth Jaroenjittichai, Koichiro Sugiyama, B. Hutawarakorn Kramer, Boonrucksar Soonthornthum, Takuya Akahori , et al. · 2022

This White Paper summarises potential key science topics to be achieved with Thai National Radio Telescope (TNRT). The commissioning phase has started in mid 2022. The key science topics consist of "Pulsars and Fast Radio Bursts (FRBs)", "…

Diffuse radio source candidate in CIZA J1358.9-4750 Open

Kohei Kurahara, Takuya Akahori, Ruta Kale, Hiroki Akamatsu, Yutaka Fujita , et al. · 2022

We report on results of our upgraded Giant Metrewave Radio Telescope (uGMRT) observations for an early-stage merging galaxy cluster, CIZA J1358.9-4750 (CIZA1359), in Band-3 (300--500 MHz). We achieved the image dynamic range of $\sim 38,00…

Wavelets and sparsity for Faraday tomography Open

Suchetha Cooray, Tsutomu T. Takeuchi, Shinsuke Ideguchi, Takuya Akahori, Y. Miyashita , et al. · 2022

Faraday tomography through broad-band polarimetry can provide crucial information on magnetized astronomical objects, such as quasars, galaxies, or galaxy clusters. However, the limited wavelength coverage of the instruments requires that …

Effects of depolarizing intervening galaxies on background radio emission. I. Global disk magnetic field Open

Rikuto Omae, Takuya Akahori, Mami Machida · 2022

External galaxies often intervene in front of background radio sources such as quasars and radio galaxies. Linear polarization of the background emission is depolarized by Faraday rotation of inhomogeneous magnetized plasma of the interven…

On the potential of faraday tomography to identify shock structures in supernova remnants Open

Shinsuke Ideguchi, Tsuyoshi INOUE, Takuya Akahori, Keitaro Takahashi · 2022

Knowledge about the magnetic fields in supernova remnants (SNRs) is of paramount importance for constraining Galactic cosmic ray acceleration models. It could also indirectly provide information on the interstellar magnetic fields. In this…

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