Teppei Okumura
A5062560508- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Electronic and Structural Properties of Oxides
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Black Holes and Theoretical Physics
- ZnO doping and properties
- Statistical and numerical algorithms
- Dark Matter and Cosmic Phenomena
- Remote Sensing in Agriculture
- Additive Manufacturing and 3D Printing Technologies
- Opinion Dynamics and Social Influence
- Magnetic and transport properties of perovskites and related materials
- History and Developments in Astronomy
- Ferroelectric and Piezoelectric Materials
Institute of Astronomy and Astrophysics, Academia Sinica
2016-2025
Theodore Roosevelt High School
2025
Kavli Institute for the Physics and Mathematics of the Universe
2016-2025
The University of Tokyo
2016-2025
Academia Sinica
2021
Kyoto University
2020
Daido Steel (Japan)
2017
Ewha Womans University
2010-2014
Tokyo University of Science
2012-2014
Nagoya University
2008-2012
Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing all except Mercury. We report detection a with microlensing. identify two masses ∼0.71 and ∼0.27 times mass Jupiter orbital separations ∼2.3 ∼4.6 astronomical units orbiting primary star ∼0.50 at distance ∼1.5 kiloparsecs. This...
We present the first measurement of planet frequency beyond "snow line," for planet-to-star mass-ratio interval −4.5 < log q −2, corresponding to range ice giants gas giants. find at mean mass ratio = 5 × 10−4 with no discernible deviation from a flat (Öpik's law) distribution in log-projected separation s. The determination is based on sample six planets detected intensive follow-up observations high-magnification (A>200) microlensing events during 2005–2008. sampled host stars have typical...
We measure the redshift-space correlation function from a spectroscopic sample of 2783 emission line galaxies FastSound survey. The survey, which uses Subaru Telescope and covers redshift ranges $1.19<z<1.55$, is first cosmological study at such high redshifts. detect clear anisotropy due to distortions (RSD) both in as separations parallel perpendicular sight its quadrupole moment. RSD has been extensively used test general relativity on scales $z<1$. Adopting LCDM cosmology with fixed...
We report the detection of an extrasolar planet mass ratio q ~ 2 x 10^(-4) in microlensing event MOA-2007-BLG-192. The best fit model shows both parallax and finite source effects, these can be combined to obtain lens masses M = 0.060 (+0.028 -0.021) M_sun for primary m 3.3 (+4.9 -1.6) M_earth planet. However, observational coverage planetary deviation is sparse incomplete, radius was estimated without benefit a star color measurement. As result, 2-sigma limits on measurements are weak....
We present the discovery of a Neptune-mass planet OGLE-2007-BLG-368Lb with planet–star mass ratio q = [9.5 ± 2.1] × 10−5 via gravitational microlensing. The planetary deviation was detected in real-time thanks to high cadence Microlensing Observations Astrophysics survey, light-curve monitoring and intensive follow-up observations. A Bayesian analysis returns stellar distance at Ml 0.64+0.21−0.26 M☉ Dl 5.9+0.9−1.4 kpc, respectively, so separation are Mp 20+7−8 M⊕ 3.3+1.4−0.8 AU,...
We study the large-scale anisotropic two-point correlation function using 46,760 luminous red galaxies at redshifts 0.16-0.47 from Sloan Digital Sky Survey. measure as a of separations parallel and perpendicular to line sight in order take account anisotropy structure redshift space. find slight signal baryonic features function, i.e., "baryon ridge" corresponding baryon acoustic peak spherically averaged which has already been reported same sample. The ridge primarily spherical with known...
The authors study the relation between underlying matter distribution and galaxies (the galaxy bias problem), present a vast compelling of nonlocal higher order contributions to dark halo bias. They investigate how well different models fit simulated halos, demonstrate need include terms in accurately model statistics halos.
We report the detection of cool, Jovian-mass planet MOA-2007-BLG-400Lb. The was detected in a high-magnification microlensing event (with peak magnification A_max = 628) which primary lens transited source, resulting dramatic smoothing event. angular extent region perturbation due to is significantly smaller than size and as result planetary signature also smoothed out by finite source size. Thus deviation from single-lens fit broad relatively weak (~ few percent). Nevertheless, we...
Aims. We report the discovery of a planet with high planet-to-star mass ratio in microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over 12-day interval, one longest for any planetary event. The host is an M dwarf, range 0.07 M⊙ < Mhost 0.49 at 90% confidence. planet-star q = 0.0132 ± 0.003 has been measured extremely well, so best-estimated mass, mp 2.6 Jupiter masses median 0.19 M⊙.
We investigate the orientation correlation of giant elliptical galaxies by measuring intrinsic ellipticity function 83,773 luminous red (LRGs) at redshifts 0.16 -0.47 from Sloan Digital Sky Survey.We have accurately determined up to 30 h -1 Mpc.Luminosity dependence is also detected although error bars are large, while no evidence found for its redshift evolution between z = 0.2 and 0.4.Then we use a cosmological N -body simulation examine misalignment central LRGs their parent dark matter...
Parallax is the most fundamental technique for measuring distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 B.C.E.) measure distance Moon, baseline of Earth so small that can generally only be applied objects in Solar System. However, there exists a class extreme gravitational microlensing events which effects readily detected and permit measurement distance, mass, transverse velocity lens. Here we report observations...
Abstract Since the discovery of accelerated expansion present universe, significant theoretical developments have been made in area modified gravity. In meantime, cosmological observations providing more high-quality data, allowing us to explore gravity on scales. To bridge recent and observations, we an overview a variety theories observables cosmic microwave background large-scale structure, supplemented with summary predictions for derived from perturbations sophisticated numerical...
Abstract We present updated constraints on cosmological parameters in a 12-parameter model, extending the standard six-parameter ΛCDM by including dynamical dark energy (DE ; w 0 , ), sum of neutrino masses (∑ m ν effective number non-photon radiation species ( N eff lensing amplitude scaling A lens and running scalar spectral index α s ). For cosmic wave background (CMB) data, we use Planck Public Release (PR) 4 (2020) HiLLiPoP LoLLiPoP likelihoods, PR4+Atacama Cosmology Telescope (ACT) DR6...
We present a new analysis of the Jupiter+Saturn analog system, OGLE-2006-BLG-109Lb,c, which was first double planet system discovered with gravitational microlensing method. This is only multi-planet by any method measured masses for star and both planets. In addition to signatures two planets, this event also exhibits parallax signature finite source effects that provide direct measure expected brightness host confirmed Keck AO imaging, yielding M_* = 0.51(+0.05-0.04) M_sun, M_b 231+-19...
Abstract We report the first constraints on growth rate of universe, f ( z ) σ 8 ), with intrinsic alignments (IAs) galaxies. measure galaxy density-intrinsic ellipticity cross-correlation and autocorrelation functions over 0.16 < 0.7 from luminous red galaxies (LRGs) LOWZ CMASS samples in Sloan Digital Sky Survey (SDSS) SDSS-III BOSS survey. detect clear anisotropic signals IA due to redshift-space distortions. By combining measured statistics conventional clustering statistics, we...
It was recently shown that the power spectrum in redshift space can be written as a sum of cross-power spectra between number weighted velocity moments, which lowest are density and momentum density. We investigate numerically properties these for simulated galaxies dark matter halos compare them to spectra, generalizing concept bias density-density spectra. Because all quantities this approach is well defined even sparse systems such massive halos. This contrasts previous approaches RSD...
We develop a perturbative approach to redshift space distortions (RSD) using the phase distribution function and apply it dark matter power spectrum its moments. RSD can be written as sum over density weighted velocity moments correlators, with lowest order being density, momentum stress energy density. use standard extended perturbation theory (PT) determine their auto cross comparing them N-body simulations. show which of terms modeled well PT need additional that include higher...
Measurement of redshift-space distortions (RSD) offers an attractive method to directly probe the cosmic growth history density perturbations. A distribution function approach where RSD can be written as a sum over weighted velocity moment correlators has recently been developed. In this paper we use results N-body simulations investigate individual contributions and convergence expansion for dark matter. If series is expanded powers μ, cosine angle between Fourier mode line sight, then...
Direct measurements of peculiar velocities galaxies and clusters can in principle provide explicit information on the three dimensional mass distribution, but this is modulated by fact that velocity field sampled at galaxy positions, thus probing momentum. We derive expressions for cross power spectrum between density momentum auto redshift space, extending distribution function method to these statistics. The resulting spectra space are expressed as infinite sums over moment correlators...
Abstract We reconstruct the two-dimensional (2D) matter distributions in 20 high-mass galaxy clusters selected from CLASH survey by using new approach of performing a joint weak gravitational lensing analysis 2D shear and azimuthally averaged magnification measurements. This combination allows for complete field, effectively breaking mass-sheet degeneracy. In Bayesian framework, we simultaneously constrain mass profile morphology each individual cluster, assuming an elliptical...
<ns3:p>During the most active period of star formation in galaxies, which occurs redshift range 1 <ns3:italic>< z <</ns3:italic> 3, strong bursts result significant quantities dust, obscures new stars being formed as their UV/optical light is absorbed and then re-emitted infrared, redshifts into mm/sub-mm bands for these early times. To get a complete picture high-<ns3:italic>z</ns3:italic> galaxy population, we need to survey large patch sky sub-mm with sufficient angular resolution...
The linear growth factor of density perturbations is generally believed to be a powerful observable quantity future large redshift surveys probe physical properties dark energy and distinguish among various gravity theories. We investigate systematic effects on determination the f from measurement redshift-space distortions. Using set high-resolution N-body simulations, we identify matter halos over broad mass range. compute power spectra correlation functions for then how well distortion...
We examine whether the gravitational shear–intrinsic ellipticity (GI) correlation function of luminous red galaxies (LRGs) can be modeled with distribution a misalignment angle advocated recently by Okumura et al. For this purpose, we have accurately measured GI for LRGs in Data Release 6 (DR6) Sloan Digital Sky Survey (SDSS), which confirms results Hirata who used DR4 data. By comparing functions simulation and observation, find that current ΛCDM model if follows Gaussian zero mean typical...
Numerical simulations show that redshift space distortions (RSD) introduce strong scale dependence in the power spectra of halos, with ten percent deviations relative to linear theory predictions even on relatively large scales (k < 0.1h/Mpc) and absence satellites (which induce Fingers-of-God, FoG, effects). If unmodeled these effects prevent one from extracting cosmological information RSD surveys. In this paper we use Eulerian perturbation (PT) halo biasing model apply it distribution...
Theoretical modeling of the redshift-space power spectrum galaxies is crucially important to correctly extract cosmological information from redshift surveys. The task complicated by nonlinear biasing and space distortion effects, which change with halo mass, wide distribution masses their occupations galaxies. One main challenges existence satellite that have both radial large virial velocities inside halos, a phenomenon known as Finger-of-God effect. We present model for galaxy in we...