Papers

Papers

Fast optical flares from M dwarfs detected by a one-second-cadence survey with Tomo-e Gozen

Masataka Aizawa, Kojiro Kawana, Kazumi Kashiyama, Ryou Ohsawa, Hajime Kawahara, Fumihiro Naokawa, Tomoyuki Tajiri, Noriaki Arima, Hanchun Jiang, Tilman Hartwig, Kotaro Fujisawa, Toshikazu Shigeyama, Ko Arimatsu, Mamoru Doi, Toshihiro Kasuga, Naoto Kobayashi, Sohei Kondo, Yuki Mori, Shin-ichiro Okumura, Satoshi Takita, Shigeyuki Sako, arXiv:2206.12847, Accepted by PASJ (2022)

A Super-Earth Orbiting Near the Inner Edge of the Habitable Zone around the M4.5-dwarf Ross 508

Hiroki Harakawa, Takuya Takarada, Yui Kasagi, Teruyuki Hirano, Takayuki Kotani, Masayuki Kuzuhara, Masashi Omiya, Hajime Kawahara et al. arXiv:2205.11986, Accepted by PASJ (2022)

Global Mapping of Surface Composition on an Exo-Earth Using Sparse Modeling

Atsuki Kuwata, Hajime Kawahara, Masataka Aizawa, Takayuki Kotani, Motohide Tamura arXiv:2204.01996, ApJ 930, 162 (2022)

Images of Embedded Jovian Planet Formation At A Wide Separation Around AB Aurigae

Thayne Currie, Kellen Lawson, Glenn Schneider, Wladimir Lyra, John Wisniewski, Carol Grady, Olivier Guyon, Motohide Tamura, Takayuki Kotani, Hajime Kawahara, Timothy Brandt, Taichi Uyama, Takayuki Muto, Ruobing Dong, Tomoyuki Kudo, Jun Hashimoto, Misato Fukagawa, Kevin Wagner, Julien Lozi, Jeffrey Chilcote, Taylor Tobin, Tyler Groff, Kimberly Ward-Duong, William Januszewski, Barnaby Norris, Peter Tuthill, Nienke van der Marel, Michael Sitko, Vincent Deo, Sebastien Vievard, Nemanja Jovanovic, Frantz Martinache, Nour Skaf, arXiv:2204.00633, Nat Astron (2022) https://doi.org/10.1038/s41550-022-01634-x

Dippers from TESS Full-frame Images. II. Spectroscopic Characterization of Four Young Dippers

Yui Kasagi, Takayuki Kotani, Hajime Kawahara, Tomoyuki Tajiri, Takayuki Muto, Masataka Aizawa, Michiko S. Fujii, Kohei Hattori, Kento Masuda, Munetake Momose, Ryou Ohsawa, Satoshi Takita arXiv:2201.09459, ApJS 259 40 (2022)

Polarization-based Speckle Nulling Using a Spatial Light Modulator to Generate a Wide-field Dark Hole

Naoshi Murakami, Kenta Yoneta, Kenya Kawai, Hajime Kawahara, Takayuki Kotani, Motohide Tamura, and Naoshi Baba, IOP, AJ 163 129 (2022)

Autodifferentiable Spectrum Model for High-Dispersion Characterization of Exoplanets and Brown Dwarfs

Hajime Kawahara, Yui Kawashima, Kento Masuda, Ian J. M. Crossfield, Erwan Pannier, Dirk van den Bekerom arXiv:2105.14782, ApJS 258 31 (2022)

First Detection of Hydroxyl Radical Emission from an Exoplanet Atmosphere: High-dispersion Characterization of WASP-33b using Subaru/IRD

Stevanus K. Nugroho, Hajime Kawahara, Neale P. Gibson, Ernst J. W. de Mooij, Teruyuki Hirano, Takayuki Kotani, Yui Kawashima, Kento Masuda, Matteo Brogi, Jayne L. Birkby, Chris A. Watson, Motohide Tamura, Konstanze Zwintz, Hiroki Harakawa, Tomoyuki Kudo, Masayuki Kuzuhara, Klaus Hodapp, Masato Ishizuka, Shane Jacobson, Mihoko Konishi, Takashi Kurokawa, Jun Nishikawa, Masashi Omiya, Takuma Serizawa, Akitoshi Ueda, Sébastien Vievard, ApJL 910, 9(2021) arXiv:2103.03094,

Neutral metals in the atmosphere of HD149026b

Masato Ishizuka, Hajime Kawahara, Stevanus K. Nugroho, Yui Kawashima, Teruyuki Hirano, Motohide Tamura, AJ 161, 153 (2021), arXiv:2102.00211, Research highlight,

Dippers from the TESS Full-Frame Images I: The Results of the first 1 year data and Discovery of A Runaway dipper

Tomoyuki Tajiri, Hajime Kawahara, Masataka Aizawa, Michiko S. Fujii, Kohei Hattori, Yui Kasagi, Takayuki Kotani, Kento Masuda, Munetake Momose, Takayuki Muto, Ryou Ohsawa, Satoshi Takita, ApJS, 251, 2 (2020) arXiv:2009.12830,

Bayesian Dynamic Mapping of an Exo-Earth from Photometric Variability

Hajime Kawahara, Kento Masuda, ApJ 900, 48 (2020), arXiv:2007.13096,

Detection of Fe I Emission in the Day-side Spectrum of WASP-33b

Stevanus K. Nugroho, Neale P. Gibson, Ernst J. W. de Mooij, Miranda K. Herman, Chris A. Watson, Hajime Kawahara, Stephanie Merrit, ApJL 898, L31 (2020), arXiv:2007.05508,

Obliquity of an Earth-like planet from frequency modulation of its direct imaged lightcurve: mock analysis from general circulation model simulation

Yuta Nakagawa, Takanori Kodama, Masaki Ishiwatari, Hajime Kawahara, Yasushi Suto, Yoshiyuki O. Takahashi, George L. Hashimoto, Kiyoshi Kuramoto, Kensuke Nakajima, Shin-ichi Takehiro, Yoshi-Yuki Hayashi, ApJ 898, 95 (2020), arXiv:2006.11437,

Global Mapping of the Surface Composition on an Exo-Earth using Color Variability

Hajime Kawahara, ApJ 894 58 (2020), arXiv:2004.03931,

Global Mapping of an Exo-Earth using Sparse Modeling

Masataka Aizawa, Hajime Kawahara, Siteng Fan, ApJ 896, 22 (2020) arXiv:2004.03941,

Searching for Thermal Inversion Agents in the Transmission Spectrum of MASCARA-2b/KELT-20b: Detection of Neutral Iron and Ionised Calcium H&K Lines

Stevanus K. Nugroho, Neale P. Gibson, Ernst J. W. de Mooij, Chris A. Watson, Hajime Kawahara, Stephanie Merritt, MNRAS 496, 504 (2020) arXiv:2003.04856,

Mutual Orbital Inclinations Between Cold Jupiters and Inner Super-Earths

Kento Masuda, Joshua N. Winn, Hajime Kawahara, AJ 159, 38 (2020), arXiv:1912.00387,

Self-lensing Discovery of a 0.2M⊙ White Dwarf in an Unusually Wide Orbit Around a Sun-like Star

Kento Masuda, Hajime Kawahara, David W. Latham, Allyson Bieryla, Masanobu Kunitomo, Morgan MacLeod, Wako Aoki , ApJL 881, 1 (2019), arXiv:1907.07656, AAS NOVA,

Transiting Planets near the Snow Line from Kepler. I. Catalog

Hajime Kawahara, Kento Masuda, AJ 157, 6 (2019), arXiv:1904.04980,

Back to “Normal” for the Disintegrating Planet Candidate KIC 12557548 b

Everett Schlawin, Teruyuki Hirano, Hajime Kawahara, Johanna Teske, Elizabeth Green on Benjamin V. Rackham, Jonathan Fraine, Rafia Bushra, AJ 157, 6 (2018) arXiv:1810.10012, AJ,

A Linear and Quadratic Time-Frequency Analysis of Gravitational Waves from Core-Collapse Supernovae

Hajime Kawahara, Takami Kuroda, Tomoya Takiwaki, Kazuhiro Hayama, Kei Kotake, ApJ 867, 2 (2018) arXiv:1810.00334, ApJ,

X-ray study of the double radio relic Abell 3376 with Suzaku

I. Urdampilleta, H. Akamatsu, F. Mernier, J. S. Kaastra, J. de Plaa, T. Ohashi, Y. Ishisaki, H. Kawahara, A&A 618, A74 (2018) arXiv:1806.07817,

Radial Velocity Follow-up of the Disintegrating Planet KIC 12557548b

Kento Masuda, Teruyuki Hirano, Hajime Kawahara, Bun’ei Sato, RNAAS, 2, 50 (2018) ADS,

Systematic Search for Rings around Kepler Planet Candidates: Constraints on Ring Size and Occurrence Rate

Masataka Aizawa, Kento Masuda, Hajime Kawahara, Yasushi Suto, AJ, 155, 206 (2018) arXiv:1803.09114,

Discovery of Three Self-lensing Binaries from Kepler

Hajime Kawahara, Kento Masuda, Morgan MacLeod, David W. Latham, Allyson Bieryla, Othman Benomar, AJ 155, 144(2018), arXiv:1801.07874,

High-Resolution Spectroscopic Detection of TiO and Stratosphere in the Day-side of WASP-33b

Stevanus K. Nugroho, Hajime Kawahara, Kento Masuda, Teruyuki Hirano, Takayuki Kotani, Akito Tajitsu, AJ 154,221 (2017), arXiv:1710.05276,

Suzaku and Chandra observations of the galaxy cluster RXC J1053.7+5453 with a radio relic

Madoka Itahana, Motokazu Takizawa, Hiroki Akamatsu, Reinout J. van Weeren, Hajime Kawahara, Yasushi Fukazawa, Jelle S. Kaastra, Kazuhiro Nakazawa, Takaya Ohashi, Naomi Ota, Huub J. A. Röttgering, Jacco Vink, Fabio Zandanel, PASJ 69,88 (2017), arXiv:1708.07004,

Towards Detection of Exoplanetary Rings Via Transit Photometry: Methodology and a Possible Candidate

Masataka Aizawa, Sho Uehara, Kento Masuda, Hajime Kawahara, Yasushi Suto, AJ 153,193 (2017), arXiv:1702.08252,

Suzaku observations of the merging galaxy cluster Abell2255: The northeast radio relic

H. Akamatsu, M. Mizuno, N. Ota, Y.-Y. Zhang, R. J. van Weeren, H. Kawahara, Y. Fukazawa, J. S. Kaastra, M. Kawaharada, K. Nakazawa, T. Ohashi, H.J.A. Röttgering, M. Takizawa, J. Vink, F. Zandanel, A&A 600, A100 (2017), arXiv:1612.03058,

Frequency Modulation of Directly Imaged Exoplanets: Geometric Effect as a Probe of Planetary Obliquity

Hajime Kawahara, ApJ 822, 112 (2016), arXiv:1603.02898,

Transiting Planet Candidates Beyond the Snow Line Detected by Visual Inspection of 7557 Kepler Objects of Interest

Sho Uehara, Hajime Kawahara, Kento Masuda, Shin’ya Yamada, Masataka Aizawa, ApJ, 822, 2 (2016), arXiv:1602.07848,

Suzaku Observations of the Galaxy Cluster 1RXS J0603.3+4214: Implications of Particle Acceleration Processes in Toothbrush Radio Relic

  1. Itahana, M. Takizawa, H. Akamatsu, T. Ohashi, Y. Ishisaki, H. Kawahara, R. J. Van Weeren, PASJ 67,113 (2015), arXiv:1508.05845,

Suzaku X-ray study of the double radio relic galaxy cluster CIZA J2242.8+5301

  1. Akamatsu, R. J. van Weeren, G. A. Ogrean, H. Kawahara, A. Stroe, D. Sobral, M. Hoeft, H. Röttgering, M. Brüggen, J. S. Kaastra, A&A 582, A87 (2015) arXiv:1507.02285,

Absolute Dimensions of a Flat Hierarchical Triple System KIC 6543674 from the Kepler Photometry

Kento Masuda, Sho Uehara, Hajime Kawahara, ApJL, 806, L37 (2015), arXiv:1506.01891,

Lifetime and Spectral Evolution of a Magma Ocean with a Steam Atmosphere: Its Detectability by Future direct Imaging

Keiko Hamano, Hajime Kawahara, Yutaka Abe, Masanori Onishi, George L. Hashimoto, ApJ, 806, 216 (2015), arXiv:1505.03552,

Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths

Yuichi Ito, Masahiro Ikoma, Hajime Kawahara, Hiroko Nagahara, Yui Kawashima, and Taishi Nakamoto, ApJ, 801, 144 (2014), arXiv:1501.05393,

Characterizing Earth-like Planets Using a Combination of High-Dispersion Spectroscopy and High-Contrast Instruments: Doppler-shifted Water and Oxygen Lines

Hajime Kawahara, Teruyuki Hirano arXiv:1409.5740,

Spectroscopic Coronagraphy for Planetary Radial Velocimetry of Exoplanets

Hajime Kawahara, Naoshi Murakami, Taro Matsuo, Takayuki Kotani, accepted for publication in ApJS, ApJS, 212, 27 (2014), arXiv:1404.5712, IOP

Exploring Hot Gas at Junctions of Galaxy Filaments with Suzaku

Ikuyuki Mitsuishi, Hajime Kawahara, Norio Sekiya, Shin Sasaki, Thierry Sousbie, Noriko Yamasaki, ApJ, 783, 137 (2014), arXiv:1311.5042, IOP

Starspots - Transit Depth Relation of the Evaporating Planet Candidate KIC 12557548b

Hajime Kawahara, Teruyuki Hirano, Kenji Kurosaki, Yuichi Ito, Masahiro Ikoma, ApJ Letters 776, L6 (2013), arXiv:1308.1585, IOP

Probing the extreme planetary atmosphere of WASP-12b

Mark Swain, Pieter Deroo, Giovanna Tinetti, Morgan Hollis, Marcell Tessenyi, Michael Line, Hajime Kawahara, Yuka Fujii, Adam Showman, Sergey Yurchenko, Icarus 225,432-445 (2013), arXiv:1205.4736, Icarus

Validity of Hydrostatic Equilibrium in Galaxy Clusters from Cosmological Hydrodynamical Simulations

Daichi Suto, Hajime Kawahara, Tetsu Kitayama, Shin Sasaki, Yasushi Suto, Renyue Cen, ApJ, 767, 79 (2013), arXiv:1302.5172

Systematic X-ray Analysis of Radio Relic Clusters with SUZAKU

Hiroki Akamatsu, Hajime Kawahara, PASJ, 65,16 (2013), ADS, PASJ

The Spin Effect on Planetary Radial Velocimetry of Exoplanets

Hajime Kawahara, ApJ Letters 760, L13 (2012), arXiv:1209.0101 , IOP

Can Ground-based Telescopes Detect The Oxygen 1.27 Micron Absorption Feature as a Biomarker in Exoplanets ?

Hajime Kawahara, Taro Matsuo, Michihiro Takami, Yuka Fujii, Takayuki Kotani, Naoshi Murakami, Motohide Tamura, Olivier Guyon, ApJ 758, 13 (2012), arXiv:1206.0558 , IOP

Mapping Earth-analogs from Photometric Variability: Spin-Orbit Tomography for Planets in Inclined Orbits

Yuka Fujii, Hajime Kawahara, ApJ, 755, 101 (2012), arXiv:1204.3504 , IOP

Mapping Clouds and Terrain of Earth-like Planets from Photometric Variability : Demonstration with Planets in Face-on Orbits

Hajime Kawahara, Yuka Fujii, ApJ Letters 739, L62 (2011), arXiv:1106.0136 , IOP

Colors of a Second Earth II: Effects of Clouds on Photometric Characterization of Earth-like Exoplanets

Yuka Fujii, Hajime Kawahara, Yasushi Suto, Satoru Fukuda, Teruyuki Nakajima, Timothy A. Livengood, Edwin L. Turner, ApJ,738,184 (2011), arXiv:1102.3625 , IOP

SUZAKU Observation of a New Merging Group of Galaxies at a Filamentary Junction

Hajime Kawahara, Hiroshi Yoshitake, Takahiro Nishimichi, Thierry Sousbie, ApJ Letters,727,L38 (2011), ADS, IOP

Studying the Warm-Hot Intergalactic Medium in Emission

Yoh Takei, Eugenio Ursino, Enzo Branchini, Takaya Ohashi, Hajime Kawahara, Kazuhisa Mitsuda, Luigi Piro, Alessandra Corsi, Lorenzo Amati, Jan-Willem den Herder, Massimiliano Galeazzi, Jelle Kaastra, Lauro Moscardini, Fabrizio Nicastro, Frits Paerels, Mauro Roncarelli, Matteo Viel, ApJ 734,91 (2011), arXiv:1011.2116 , IOP

The persistent cosmic web and its filamentary structure II: Illustrations

Thierry Sousbie,Christophe Pichon, Hajime Kawahara, MNRAS,414,384 (2011), ADS, MNRAS

Impact of Chandra calibration uncertainties on galaxy cluster temperatures: application to the Hubble Constant

Erik D. Reese, Hajime Kawahara, Tetsu Kitayama, Naomi Ota, Shin Sasaki, Yasushi Suto, ApJ,721,653 (2010), ADS, IOP

Global Mapping of Earth-like Exoplanets from Scattered Light Curves

Hajime Kawahara, Yuka Fujii, ApJ,720,1333 (2010), ADS, IOP

The axis ratio distribution of X-ray clusters observed by XMM-Newton

Hajime Kawahara, ApJ,719,1926 (2010), ADS, IOP

Colors of a Second Earth: Estimating the fractional areas of ocean, land, and vegetation of Earth-like exoplanets

Y. Fujii, H. Kawahara, Y. Suto, A. Taruya, S. Fukuda, T. Nakajima, E. L. Turner, ApJ,715,866 (2010), ADS, IOP

Inhomogeneity in Intracluster Medium and Its Cosmological Implications

Hajime Kawahara, Ph.D. thesis, The University of Tokyo, (2009) zenodo

Extracting Galaxy Cluster Gas Inhomogeneity from X-Ray Surface Brightness: A Statistical Approach and Application to Abell 3667

Hajime Kawahara, Erik D. Reese, Tetsu Kitayama, Shin Sasaki, Yasushi Suto, ApJ,687,936 (2008), ADS, IOP

Systematic Errors in the Hubble Constant Measurement from the Sunyaev-Zel’dovich Effect

Hajime Kawahara, Tetsu Kitayama, Shin Sasaki, Yasushi Suto, ApJ,674,11 (2008), ADS, IOP

X-Ray Study of Temperature and Abundance Profiles of the Cluster of Galaxies Abell 1060 with Suzaku

Kosuke Sato, Noriko Y. Yamasaki, Manabu Ishida, Yoshitaka Ishisaki, Takaya Ohashi, Hajime Kawahara, Takao Kitaguchi, Madoka Kawaharada, Motohide Kokubun, Kazuo Makishima, Naomi Ota, Kazuhiro Nakazawa, Takayuki Tamura, Kyoko Matsushita, Naomi Kawano, Yasushi Fukazawa, John P. Hughes, PASJ, 59,299 (2007), ADS

Radial Profile and Lognormal Fluctuations of the Intracluster Medium as the Origin of Systematic Bias in Spectroscopic Temperature

Hajime Kawahara, Yasushi Suto, Tetsu Kitayama, Shin Sasaki, Mamoru Shimizu, Elena Rasia, Klaus Dolag, ApJ, 659,257 (2007), ADS, IOP

Soft X-Ray Transmission Spectroscopy of a Warm/Hot Intergalactic Medium with XEUS

Hajime Kawahara, Kohji Yoshikawa, Shin Sasaki, Yasushi Suto, Nobuyuki Kawai, Kazuhisa Mitsuda, Takaya Ohashi, Noriko Yamasaki, PASJ,58,657 (2006), ADS