The Astrophysical Journal Letters

Over 10 years of monitoring

Using XRISM, JAXA’s new high-precision X-ray spectroscopic satellite, researchers observed a stellar-mass black hole in the Milky Way and detected highly ionized iron absorption lines — clear signatures of hot gas. Remarkably, this detection was achieved at the dimmest X-ray state ever reported for such a system. The results reveal the complex structure and motion of gas around the black hole, offering new insights into the dynamic behavior of black holes.

Using the Subaru Telescope and Gemini North telescope, an international team of astronomers including Kavli IPMU (WPI) has found the earliest pair of quasars, monsters shining with intense radiation powered by actively feeding super massive black holes.

Survey observations with the Subaru Telescope have led to the discovery of 22 quasars in the very distant universe. Their space density indicates the rapid emergence of supermassive black holes soon after the Big Bang, providing strong constraints on models of when, where, and how they formed and grew in cosmic space-time. The results also indicate a small quasar contribution to cosmic reionization, a major phase transition of the early universe.

Current evidence suggests that microparticles of cosmic dust collide and stick together to form larger dust aggregates that may eventually combine and develop into planets. Numerical models that accurately characterize the conditions required for colliding microparticle aggregates to stick together, rather than bounce apart, are therefore paramount to understanding the evolution of planets. Recent modeling suggests that dust aggregates are less likely to stick together after a collision as the size of the aggregates increases.

A team led by Kavli IPMU researchers have found the earliest evidence of parts of the universe that were heated to temperatures more characteristic to the intergalactic gas medium where most atoms reside in the universe today.

An international research team has discovered the first example of a supernova, known as SN 2018ivc, showing an unprecedented rebrightening at millimeter wavelengths about one year after the explosion. With the help of the Atacama Large Millimeter/submillimeter Array -- or ALMA -- the analysis revealed that the dying massive star ejected a large amount of its envelope due to a strong binary interaction with a companion star that took place about 1500 years before the explosion. In a paper published in The Astrophysical Journal Letters, the team posits that this rebrightening event in SN 2018ivc provides a missing link between supernovae -- or SN -- that occur in binary star systems and those that involve solitary massive stars.

Researchers used the James Webb Space Telescope to identify the precise location of a powerful energy source hidden by cosmic dust in the luminous merging galaxy IIZw096.

A team including Kavli IPMU has studied the relation between galaxy size and luminosity of some of the earliest galaxies in the universe taken by the James Webb Space Telescope, less than a billion years after the Big Bang.

Supermassive black holes can launch fast-moving plasma, which emit strong radio signals known as radio jets. Despite being discovered over 40 years ago, much remains unknown about how radio jets are produced. Now, a research team, led by Tohoku University astrophysicists, has attempted to clarify how plasma gets loaded into radio jets.

Researchers at Osaka Metropolitan University have observed "baby stars" in the Small Magellanic Cloud, having an environment similar to the early universe. Toward one of the baby stars, they found molecular outflow, which has similar properties to those seen in the Milky Way galaxy, giving a new perspective on the birth of stars.

A team of astronomers including Kavli IPMU discovered a mysterious short-duration astronomical event that was as bright as a superluminous supernova, but evolving much faster, reports a new study.

A team of astronomers including Kavli IPMU's Ji-an Jiang has discovered the fastest optical flash of a Type Ia supernova.

Researchers have developed a novel technique to investigate the dynamics of the early Solar System by analyzing magnetites in meteorites utilizing the wave nature of electrons.

Astronomers obtained the first resolved image of disturbed gaseous clouds in a galaxy 11 billion light-years away by using ALMA.

An international team of astronomers using ALMA has captured the very moment when an old star first starts to alter its environment.

A distant galaxy more massive than our Milky Way has revealed that the 'cores' of massive galaxies in the Universe had formed already 1.5 billion years after the Big Bang.

Japanese researchers contribute to paradigm-shifting observations of the gargantuan black hole at the heart of distant galaxy Messier 87.

ALMA has tuned in another new channel for signals from space. Using its highest frequency receivers yet, researchers obtained 695 radio signatures for various molecules in the direction of a massive star forming region. These first results from the ALMA Band 10 receivers developed in Japan ensure a promising future for high frequency observations.

Kavli IPMU of The University of Tokyo, Japan, and Instituto de Astrofisica de La Plata, Argentina, scientists have found highly magnetized, rapidly spinning neutron stars called magnetars could explain the energy source behind two extremely unusual stellar explosions.