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research.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Kiyoshi Masui - Research</title>
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<meta name="description" content="Kiyoshi Masui's reseach webpage. Kiyo's research is in radio astronomy and cosmology, spanning theory, data analysis, observations, and instrumentation" />
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<div id="header" class="width"> <span><font size="4" color='white'>Kiyoshi Masui</font></span>
<ul>
<li><a href="index.html">Home</a></li>
<li><a href="research.html"><font color='white'>Research</font></a></li>
<li><a href="about.html">About Me</a></li>
</ul>
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<br/>
<h1> Research <span class="dark"></span></h1>
<a href="http://space.mit.edu/masui-srl">
<img src="images/pics/srl_logo.svg" alt="MIT Synoptic Radio Lab" width="360" align="left" style="margin: 0px 0px 20px 0px" />
</a>
<p style="clear:both;">
<a href="http://space.mit.edu/masui-srl">My lab</a> works with wide-field,
radio-wavelength sky surveys to establish new ways to observe the Universe. These include developing
the technique of hydrogen intensity mapping for rapidly surveying large volumes of space, and exploiting
the recently-discovered phenomena of fast radio bursts (FRBs) as probes of the Universe’s contents.
This work includes creating digital instrumentation for radio telescopes, developing algorithms for
analyzing observational data, and making theoretical predictions for the signals we should be looking for.
</p>
<p>
<img src="images/pics/chime.jpg" align="left" height="269" width="360" hspace="10" alt="CHIME" />
</p>
<p>
Hydrogen intensity mapping is a technique for rapidly surveying the large-scale distribution of matter in the
Universe in three dimensions using radio emission from the 21-cm spectral line in hydrogen. Among the premier
telescopes using this technique is the Canadian Hydrogen Intensity Mapping Experiment (CHIME), which is the
main instrument used by Masui’s team. CHIME is part of a new generation of digital radio telescopes that have
no moving parts and rely on signal processing software running on large compute clusters to focus and steer.
This allows these telescopes to see large swaths of the sky simultaneously, enabling rapid surveys.
</p>
<p>
Fast radio bursts are brief and energetic flashes of radio light coming from distant galaxies. CHIME has been
outfitted with a high-time-resolution backend dedicated to searching for FRBs, allowing it to detect these
enigmatic transients at an unprecedented rate. Due to the unique properties of FRBs, they carry a record of
the matter they've encountered between their source and our telescopes. Now, a central focus is to use the
information contained in large samples of observed FRBs to help understand the evolution of the Universe.
</p>
<p>
More detail can be found at our <a href="http://space.mit.edu/masui-srl">lab page</a>.
</p>
<h1> Past <span class="dark">results</span></h1>
<h2> The Hydrogen intensity mapping survey with the GBT</h2>
<p>
<img src="images/pics/gbt.jpg" align="right" height="240" width="320" hspace="10" alt="GBT" />
I
<a href="https://iopscience.iop.org/article/10.1088/2041-8205/763/1/L20">led</a>
<a href="https://academic.oup.com/mnrasl/article/434/1/L46/1165809">a survey</a>
that pioneered the hydrogen intensity mapping technique, using the
Green Bank Telescope (GBT). The survey made a definitive detection of large-scale structure and
demonstrated that foregrounds can be subtracted down to the same level as the hydrogen signal.
The survey served as a proof-of-concept for the hydrogen mapping method and its potential
to rapidly advance observational cosmology.
</p>
<h2> FRB 110523</h2>
<p>
The
<a href="https://www.nature.com/articles/nature15769">serendipitous discovery of a fast radio burst</a>
in the data from the GBT hydrogen mapping survey. The 15th FRB ever detected, and the second at a telescope other
than Parkes, we were the first to measure linear polarization and Faraday rotation. We also detected the signatures
of two distinct patches of turbulent gas along the line of sight, showing this was inconsistent with a Milky-way origin
for FRBs and gaining some of the first clues about FRB source environments.
The discovery was covered by
<a href="http://phenomena.nationalgeographic.com/2015/12/02/those-enigmatic-blasts-of-radio-waves-from-deep-space-not-aliens/">National Geographic</a> and
<a href="http://www.scientificamerican.com/article/fast-radio-bursts-mystify-experts-mdash-for-now1/">Scientific American</a>.
</p>
<h2> FRBs as probes of the structure of the universe</h2>
<p>
An early
<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.121301">proposal</a>
for how a survey of FRBs might be used to probe the 3D distribution of matter in the Universe. The work was summarized
in <a href="https://physics.aps.org/articles/v8/90">APS's <i>Physics</i></a>.
</p>
<h2> Primordial gravitational wave fossils</h2>
<p>
<img src="images/pics/nbody.jpg" alt="Millennium large scale structure" height="300" width="400" align="right" hspace="10" />
I discovered a
<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.105.161302">tidal effect</a>
by which primordial gravitational waves generated during inflation leave a subtle, but permanent, imprint in the large-scale
structure of the universe. The effect could be used to search for the existence of gravitational waves, probe their
<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.221301">3D structure</a>, and confirm inflation.
</p>
<h2> Bitshuffle</h2>
<p>
I wrote a
<a href="https://github.com/kiyo-masui/bitshuffle">data compression software library</a> and
<a href="https://www.sciencedirect.com/science/article/abs/pii/S2213133715000694?via%3Dihub">showed</a>
that for certain
types of data, including that from radio telescopes, it is both faster and achieves better compression than other
libraries.
</p>
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<br/>
Kiyoshi Wesley Masui kmasui _at_ mit.edu tel: (617) 452-4647
office: <a href="https://whereis.mit.edu/?zoom=16&lat=42.360687340000005&lng=-71.09323996&maptype=mit&go=37&open=object-37">McNair bldg 37</a> - room 664d
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