Research

Overview

I work in the field of observational astrophysics with many enthusiastic and stimulating colleagues around the world and excellent graduate students at ISAS. Back to top

Effort rates

I update my full time effort (FTE) rate quarterly among multiple commitments to achieve a balanced portofolio. Below is the plan for the current quarter (2024 Q2).
Commitments FTE Bar
Observational astrophysics 40.0% bar
LiteBIRD project 40.0% bar
XRISM/Resolve project 5.0% bar
Teaching 10.0% bar
Community service 5.0% bar
Back to top

Projects

LiteBIRD (2017-)

Through the 10 year commitment to Hitomi SXS, I gained some experience in developing the onboard digital electronics and the spacecraft integration of a cryogenic mission. After the loss of Hitomi, I changed my career again to work for LiteBIRD, which is another JAXA-led cryogenic mission aiming to detect the large-scale anisotropy of the B-mode polarization of the cosmic microwave background to prove the theory of inflation. It is a joint mission among many agencies in the US, Canada, Europe, and Japan. I work for the design of the onboard digital electronics and the electrical architecture of the payload module, and the assessment of external noise (EMI, micro-vibration, cosmic rays, etc) effects to cosmology. [115] [114] [113] [110]
A graduate student of us lead the magnetic field emission measurements from spacecraft components that may interfere with the detectors in the magnetic shield room at ISAS.
We had proton radiation tests at HIMAC with a graduate student of us and LiteBIRD colleagues.
We hosted a meeting at ISAS to kick-off LiteBIRD with a large number of enthusiastic experts around the world.

Resolve onboard XRISM (2017-)

I continued working for the recovery mission of SXS, which is called Resolve in XRISM[101] with many experienced colleagues of NASA, SRON, JAXA, and others, and graduate students at ISAS. Amongst them, I contributed for the instrument- and spacecraft-level integration & tests, the ground calibration, and initial and commissioning phase operations. Some highlights include;
  1. Micro-vibration and electromagnetic interference for the detector, which are common topics among low temperature detectors. [123] [122] [119]
  2. Ground calibration for the X-ray transmission calibration of the cryostat window and relative timing of the microcalorimeter X-ray events. [109]
  3. Development of X-ray event screening. [137]
  4. Assessment of high count rate observations. [138]
  5. Data visualization and anomaly detection based on machine-learning technique. [126] [120]
Resolve onboard XRISM was launched with the 47th H-IIA rocket from Tanegashima on 2023 Sept 7 8:42:11 JST.
NASA and JAXA members gathered at SSOC in preparation for the first contact after the launch.
Many graduate students in our lab were awarded for their outstanding contributions to the XRISM project.
And, more.
A graduate student of us led the calibration of the Dewar gate valve for Resolve at a synchrotron facility at KEK.[109]
NASA and JAXA hardware pieces are integrated at SHI to start the Resolve instrument-level test in November 2019.

Soft X-ray Spectrometer (SXS) onboard Hitomi (2008-2017)

After I joined as a staff scientist at ISAS 2008 July, I changed my career to devote myself to the development of the SXS, which is an X-ray micro-calorimeter spectrometer onboard the ASTRO-H (Hitomi) X-ray satellite. It is a joint project among NASA/GSFC (US), SRON (the Netherlands), University of Geneva (Switzerland), and JAXA. [80] [59]
My contribution for the project started with the onboard digital electronics. I worked for the FPGA design of the onboard digital signal processing unit for event reconstruction and the electrical interface with the spacecraft. [98] [77] [58] [56]
My responsibility expanded over the years, leading the instrument and spacecraft integration, launch campaign, operation, and calibration. [97] [93] [83] [82] [81] [79] [78] [76] [74] [73] [70] [67] [48]
Our long and consistent effort resulted in unprecedented performance of the SXS in the orbit. However, the success was suddenly discontinued in 34 days of launch due to the failure of the spacecraft attitude control. Still, the SXS left a lot of legacy, both in science and technology, as the first X-ray microcalorimeter to have made astronomical observations in the orbit. [103] [95] [92] [91] [90] [89] [88] [87] [86] [85] [75] [72] [68]
I started by working for the onboard digital electronics of the SXS, which was one of the major contributions by JAXA.
I led an international team for the instrument and spacecraft integration of SXS.
Our instrument was launched on 2016 Feb 17 from Tanegashima with an HII-A rocket. I was too busy to see the view for the critical operation.
Our long and consistent team effort paid off with unprecedented performance of the SXS in the orbit.

X-ray Imaging Spectrometer (XIS) onboard Suzaku (2005-2006, 2008-2015)

I started my career by working for the XIS onboard Suzaku X-ray observatory, which was an X-ray CCD imaging-spectrometer and the workhorse of the spacecraft for 10 years. [31] [30]
I joined the team in the third year of operation. Since then, I led the in-orbit operation and calibration and contributed for many performance enhancements of the instrument to maximize scientific outputs including our own. [57] [50]
All team members spent two weeks twice a year for operating the spacecraft at the Uchinoura station.

Advanced CCD Imaging Spectrometer (ACIS) onboard Chandra (2003-2004, 2007-2008)

I joined the ACIS team at the Pennsylvania State University led by Prof. Gordon P. Garmire twice once as a JSPS fellow and the other as a Chandra fellow. I learned lots of virtues through a total of 3.5 year life in the US.
Back to top

Observational Astrophysics

See our group page for details.

White dwarf binaries

[125] [111] [99] [71] [60]

Classical novae

[64] [62] [52] [45] [44] [42] [37]

Neutron star and blackhole binaries

[133] [121] [118] [62] [53] [47] [15] [7] [4] [3] [2] [1]

AGNs and ULXs

[105] [96] [94] [66] [49]

Galactic ridge X-ray emission

[112] [69] [61] [41] [25]

SN and SNRs

[104] [93] [36]

HII regions

[65] [43] [40] [35] [34] [32] [29] [28] [27] [26] [23]

Normal stars

[129] [127] [46] [39] [38]

Young stellar objects

[33] [24] [22] [21] [20] [19] [17] [16] [13] [12] [11] [10] [9]
Back to top

Teaching

In the research group led by Prof. Ken Ebisawa, I teach graduate students for their degrees in astrophysics. Our group actively publishes research papers every year.
We take students to observations and spacecraft duties for their experience. A photo at the summit of Mauna Kea.
For the acceptance of every research paper for publication, we celebrate with a social dinner in our research group.

Below is the list of theses that I worked as one of the advisors.
Below is the list of awards for the graduate and under-graduate students that I served as a superviser.
  1. 2024 XRISM outstanding contribution awards for young researchers for launch campaign and in-orbit operation.
    1. Yuto Mochizuki "Optimization of the event screening for the low temperature detector onboard XRISM using ground and in-orbit data"
  2. 2024 SOKENDAI School of Physical Sciences Dean's Award Tomoki Omama
  3. 2023 18'th L'Oreal-UNESCO award for women in science in Japan Mayu Tominaga
  4. 2023 IGPEES final examination excellent award Mayu Tominaga
  5. 2023 XRISM outstanding contribution awards for young researchers for spacecraft-level tests.
    1. Miki Kurihara "Evaluation and testing of the electromagnetic interference to Resolve"
    2. Ryuta Imamura "Evaluation and testing of the micro-vibration interference to Resolve"
    3. Miu Kashiwazaki "Development of the anomaly detection in Resolve data using machine learning"
    4. Takuya Midooka, Mayu Tominaga, Tomoki Omama, Yuto Mochizuki "Contribution for Resolve testing"
  6. 2023 13'th excellent master thesis award for detector development Miki Kurihara "Evaluation and mitigation of electromagnetic interference in the low temperature detector onboard XRISM"
  7. 2022 XRISM outstanding contribution awards for young researchers for instrument-level tests.
    1. Takuya Midooka "X-ray transmission calibration of the Resolve gate valve"
    2. Miki Kurihara "Evaluation and testing of the electromagnetic interference to Resolve"
    3. Tomoki Omama "Relative timing calibration of Resolve X-ray events"
    4. Ryuta Imamura "Evaluation and testing of the micro-vibration interference to Resolve"
    5. Mayu Tominaga, Yuto Mochizuki "Contribution for Resolve testing"
  8. 2021 IGPEES qualify examination excellent award Mayu Tominaga
  9. 2018 17th HEAPA Ph.D. thesis award Misaki Mizumoto "On the X-ray spectral variability in the Fe-K band of active galactic nuclei"
  10. 2015 University of Tokyo, College of Science award Misaki Mizumoto "Short-time variation of X-ray spectra of black hole binaries using Suzaku"
Back to top

Community service

Journal reviewer and editor

I serve as a reviewer for many astrophysics journals and proposals. I also work as an editor of the Publications of the Astronomical Society of Japan.

IACHEC (2008-2011, 2017-2023)

I work as a member of IACHEC, a consortium of cross-calibrating high-energy astrophysics instruments in the orbit. I worked both for the XIS (X-ray CCD) and the SXS (X-ray micro-calorimeter). [54] [51]
We hosted 14th annual meeting of IACHEC in Shonan Village Center in 2019.

Development of radiative transfer codes

I contribute for the development of some radiative transfer codes for X-ray spectroscopy. [139] [135] [130] [125]

Seminars

I serve as an organizer of the department colloquium since its foundation.

Organization of workshops

Here is a list of recent workshops that we organized.
The workshop of variable stars and binaries at ISAS in 2024.
The cloudy workshop at ISAS in 2024, inviting Prof. G. Ferland and Drs. P. van Hoof and C. Gunesekera, with about 50 students.
Back to top

Public outreach

Articles

Recent interviews & press releases

Back to top