NEWS
POSTED
2022.10.17
CATEGORY
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Assistant Professor Motoko Serino (Faculty College of Science and Engineering) is participating in the launch of the OHMAN program, an international collaborative observation of X-ray celestial objects aboard the International Space Station.
An international collaborative research group* consisting of Assistant Professor Motoko Serino Aoyama Gakuin University (Department of College of Science and Engineering, Department of Physical Sciences and Engineering), Senior Researcher Takehiro Mihara of the Tamagawa High Energy Astrophysics Laboratory, RIKEN (Riken Institute of Physical and Chemical Research), Assistant Professor Wataru Iwakiri of the Faculty of College of Science and Engineering and Engineering, Chuo University, Professor Hitoshi Negoro of the College of Science and College of Science and Engineering, Nihon University, and Chief Research and Development Scientist Satoshi Nakahira of the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA), launched the OHMAN (On-orbit Hookup of MAXI and NICER) project, an on-board observation plan for X-ray transients on the International Space Station (ISS), on August 10, 2022, and successfully conducted coordinated observations on September 13.
OHMAN is an observation project that will link in real time two observation instruments on the International Space Station (ISS) that are installed for different purposes: MAXI [1], an all-sky X-ray monitor that excels at wide-area all-sky observations, and NASA's NICER [2], which excels at narrow-area detailed observations. Preparations have been underway based on an agreement reached in April 2021 under the Japan-US Open Platform Partnership Program (JP-US OP3), a framework for Japan-US cooperation aimed at maximizing the utilization of the ISS.
Traditionally, information on X-ray transients observed by MAXI was downlinked to Earth for analysis, and then the resulting transient phenomena were transmitted to other satellites via email or other means for follow-up observations. As a result, it took at least three hours from the discovery of an X-ray transient to follow-up observation. With OHMAN, data from MAXI is processed by computers on the ISS, and information on discovered X-ray transients is transmitted to NICER on the ISS without going through Earth, allowing for automatic follow-up observations. In other words, an international collaborative observatory capable of wide-area observation and detailed follow-up observation has been realized on the ISS. This makes it possible to complete the process from discovery to follow-up observation in less than 10 minutes.
Future observations by OHMAN are expected to reveal the identity of unidentified celestial objects (MUSST objects[3]) that were previously detected by MAXI but have not been detected in follow-up observations.
Conceptual diagram of OHMAN, the MAXI-NICER orbital linkage ?NASA/JAXA (Added to the cover page of the NASA/GSFC OHMAN proposal)
*International collaborative research group
Tamagawa High Energy Astrophysics Laboratory, Frontier Research Division, RIKEN
Senior Researcher: Tatehiro Mihara
Chief Researcher: Toru Tamagawa
Department of Physics, Faculty College of Science and Engineering, Chuo University
Assistant Professor Wataru Iwakiri
(Visiting Researcher, Tamagawa High Energy Astrophysics Laboratory, RIKEN Frontier Research Division)
Nihon University College College of Science and Engineering Department of Physics
Professor Hitoshi Negoro
Aoyama Gakuin University College of Science and Engineering Department of Physical Sciences
Assistant Professor Motoko Serino
Japan Aerospace Exploration Agency (JAXA) Institute of Space and Astronautical Science
Chief Research and Development Engineer: Satoshi Nakahira
Japan Aerospace Exploration Agency (JAXA) Kibo Utilization Center, External Spacecraft Use Promotion Section
MAXI teams in Japan
RIKEN, JAXA/ISAS, Tokyo Institute of Technology, Nihon University, Kyoto University, Aoyama Gakuin University,
Miyazaki University, Chuo University, Ehime University
National Aeronautics and Space Administration (NASA, United States)
Goddard Space Flight Center (GSFC)
NICER Team Representative: Keith Gendreau
Johnson Space Center (JSC) ISS Team
[1] MAXI (Maxi) all-sky X-ray monitoring system
MAXI is a Japanese observation instrument attached to the external experiment platform of the Japanese Experiment Module "Kibo" on the International Space Station. It was proposed and adopted in 1998 by Dr. Masaru Matsuoka, Chief Investigator at the RIKEN Laboratory for Cosmic Radiation. Currently, operation and data analysis are continued by the MAXI team, which consists of members from 12 domestic institutions, centered around the Tamagawa High Energy Astrophysics Laboratory. All-sky observations began on August 15, 2009, and the observation data is immediately made public on the RIKEN website (http://maxi.riken.jp). Over 13 years, it has discovered 34 X-ray novae, 14 of which were newly discovered black hole objects. The number of black hole objects discovered by a single satellite/instrument is the second highest in history, after the US X-ray Astronomy Satellite (RXTE) with 15 discoveries. MAXI stands for Monitor of All-sky X-ray Image.
[2] NICER
This refers to a neutron star interior composition explorer. It is an X-ray telescope at NASA's Goddard Space Flight Center (GSFC) mounted on the truss of the International Space Station. Observations began in July 2017. Operations are carried out by the NASA/GSFC NICER team, led by Keith Gendreau. NICER stands for Neutron star Interior Composition ExploreR. For more details, see Wikipedia (https://ja.wikipedia.org/wiki/NICER).
[3] MUSST objects
MUSST stands for MAXI unidentified short soft X-ray transient. It has not been detected by gamma-ray satellites and was detected by only one MAXI scan (an example of the light curve at the time of detection is shown in the press release and Figure 4). Despite follow-up observations by the Swift satellite, no corresponding object was detected. Because its exact location is unknown, follow-up observations in visible light and other formats have not been possible, and it remains an unidentified object. The true nature of MUSST objects may be X-ray flashes (the X-ray version of gamma-ray bursts) or flares from nearby dMe stars. However, the possibility of new astronomical phenomena such as rapid nova explosions on massive white dwarfs or gamma-ray bursts caused by the first stars in the universe is also being considered. To select the desired object from the mixed bag of MUSST objects, immediate observations in soft X-ray are necessary, and investigations by OHMAN are awaited.
