Takahiro Nishimichi

J-GLOBAL         Last updated: Jul 31, 2019 at 21:55
Takahiro Nishimichi
Kyoto University
Yukawa Institute for Theoretical Physics Research Physics under Extreme Conditions

Research Areas


Published Papers

Marco Marinucci, Takahiro Nishimichi, Massimo Pietroni
   Jul 2019
Consistency Relations for the Large Scale Structure are exact equalities
between correlation functions of different order. These relations descend from
the equivalence principle and hold for primordial perturbations generated by
single-field model...
Yosuke Kobayashi, Takahiro Nishimichi, Masahiro Takada, Ryuichi Takahashi
   Jul 2019
Clustering properties and peculiar velocities of halos in large-scale
structure carry a wealth of cosmological information over a wide range of
scales from linear to nonlinear scales. We use halo catalogs in a suite of
high-resolution Tex-body sim...
Teppei Okumura, Atsushi Taruya, Takahiro Nishimichi
   Jul 2019
The kinematic Sunyaev-Zel'dovich effect enables us to directly probe the
density-weighted velocity field up to very large cosmic scales. We investigate
the effects of intrinsic alignments (IA) of dark-matter halo shapes on cosmic
density and veloc...
Ryoma Murata, Masamune Oguri, Takahiro Nishimichi, Masahiro Takada, Rachel Mandelbaum, Surhud More, Masato Shirasaki, Atsushi J. Nishizawa, Ken Osato
   Apr 2019
Constraining the relation between the richness Tex and the halo mass Tex over
a wide redshift range for optically-selected clusters is a key ingredient for
cluster-related science in optical surveys, including the Subaru Hyper
Suprime-Cam (HSC) su...
Akinari Hamabata, Taira Oogi, Masamune Oguri, Takahiro Nishimichi, Masahiro Nagashima
   Feb 2019
The distributions of the pairwise line-of-sight velocity between galaxies and
their host clusters are segregated according to the galaxy's colour and
morphology. We investigate the velocity distribution of red-spiral galaxies,
which represents a r...
Takahiro Nishimichi, Masahiro Takada, Ryuichi Takahashi, Ken Osato, Masato Shirasaki, Taira Oogi, Hironao Miyatake, Masamune Oguri, Ryoma Murata, Yosuke Kobayashi, Naoki Yoshida
   Nov 2018
We perform an ensemble of cosmological Tex-body simulations with Tex
particles for 101 cosmological models within a flat TexCDM cosmology framework
sampled based on a maximin-distance Sliced Latin Hypercube Design. By using the
outputs of Tex...
P. Reimberg, F. Bernardeau, T. Nishimichi, M. Rizzato
   Nov 2018
We use a simple cosmological model with two parameters Tex to
illustrate the impact of using Halofit on error forecast based on Fisher
information matrix for a Tex volume survey. We show that Halofit
fails to reproduce well the...
Ken Osato, Takahiro Nishimichi, Francis Bernardeau, Atsushi Taruya
Phys. Rev. D 99, 063530 (2019)      Oct 2018
We study the accuracy with which cosmological parameters can be determined
from real space power spectrum of matter density contrast at weakly nonlinear
scales using analytical approaches. From power spectra measured in Tex-body
simulations and us...
Akinari Hamabata, Masamune Oguri, Takahiro Nishimichi
   Sep 2018
Velocity dispersions have been employed as a method to measure masses of
clusters. To complement this conventional method, we explore the possibility of
constraining cluster masses from the stacked phase space distribution of
galaxies at larger ra...
Atsushi Taruya, Takahiro Nishimichi, Donghui Jeong
Phys. Rev. D 98, 103532 (2018)      Jul 2018
Perturbation theory (PT) calculation of large-scale structure has been used
to interpret the observed non-linear statistics of large-scale structure at the
quasi-linear regime. In particular, the so-called standard perturbation theory
(SPT) provid...
Teppei Okumura, Takahiro Nishimichi, Keiichi Umetsu, Ken Osato
Phys. Rev. D 98, 023523 (2018)      Jul 2018
We investigate the splashback features of dark-matter halos based on cosmic
density and velocity fields. Besides the density correlation function binned by
the halo orientation angle which was used in the literature, we introduce, for
the first ti...
Hillary L. Child, Masahiro Takada, Takahiro Nishimichi, Tomomi Sunayama, Zachary Slepian, Salman Habib, Katrin Heitmann
Phys. Rev. D 98, 123521 (2018)      Jun 2018
The galaxy bispectrum, measuring excess clustering of galaxy triplets, offers
a probe of dark energy via baryon acoustic oscillations (BAOs). However up to
now it has been severely underused due to the combinatorically explosive number
of triangle...
Ryuichi Takahashi, Takahiro Nishimichi, Masahiro Takada, Masato Shirasaki, Kosei Shiroyama
   May 2018
In this study, we measure the response of matter and halo projected power
spectra Tex (X, Y are matter and/or halos), to a
large-scale density contrast, Tex, using separate universe
simulations. We show that the f...
Taizo Okabe, Takahiro Nishimichi, Masamune Oguri, Sébastien Peirani, Tetsu Kitayama, Shin Sasaki, Yasushi Suto
   Apr 2018
While various observations measured ellipticities of galaxy clusters and
alignments between orientations of the brightest cluster galaxies and their
host clusters, there are only a handful of numerical simulations that implement
realistic baryon p...
Hironao Miyatake, Nicholas Battaglia, Matt Hilton, Elinor Medezinski, Atsushi J. Nishizawa, Surhud More, Simone Aiola, Neta Bahcall, J. Richard Bond, Erminia Calabrese, Steve K. Choi, Mark J. Devlin, Joanna Dunkley, Rolando Dunner, Brittany Fuzia, Patricio Gallardo, Megan Gralla, Matthew Hasselfield, Mark Halpern, Chiaki Hikage, J. Colin Hill, Adam D. Hincks, Renée Hložek, Kevin Huffenberger, John P. Hughes, Brian Koopman, Arthur Kosowsky, Thibaut Louis, Mathew S. Madhavacheril, Jeff McMahon, Rachel Mandelbaum, Tobias A. Marriage, Loïc Maurin, Satoshi Miyazaki, Kavilan Moodley, Ryoma Murata, Sigurd Naess, Laura Newburgh, Michael D. Niemack, Takahiro Nishimichi, Nobuhiro Okabe, Masamune Oguri, Ken Osato, Lyman Page, Bruce Partridge, Naomi Robertson, Neelima Sehgal, Masato Shirasaki, Jonathan Sievers, Cristóbal Sifón, Sara Simon, Blake Sherwin, David N. Spergel, Suzanne T. Staggs, George Stein, Masahiro Takada, Hy Trac, Keiichi Umetsu, Alex van Engelen, Edward J. Wollack
   Apr 2018
We present weak-lensing measurements using the first-year data from the Hyper
Suprime-Cam Strategic Survey Program on the Subaru telescope for eight galaxy
clusters selected through their thermal Sunyaev-Zel'dovich (SZ) signal measured
at 148 GHz ...
Jiaxin Han, Yin Li, Yipeng Jing, Takahiro Nishimichi, Wenting Wang, Chunyan Jiang
   Feb 2018
We develop a novel approach in exploring the joint dependence of halo bias on
multiple halo properties using Gaussian process regression. Using a
TexCDM Tex-body simulation, we carry out a comprehensive study of the
joint bias dependence on ...
三橋龍也, 川島英之, 西道啓博, 西道啓博, 建部修見
電子情報通信学会論文誌 B(Web)   J100-B(12) 961‐973 (WEB ONLY)   Dec 2017
Ken Osato, Takahiro Nishimichi, Masamune Oguri, Masahiro Takada, Teppei Okumura
MNRAS, 477, 2141 (2018)      Dec 2017
We study the dependence of surface mass density profiles, which can be
directly measured by weak gravitational lensing, on the orientation of haloes
with respect to the line-of-sight direction, using a suite of Tex-body
simulations. We find that, ...
Atsushi J. Nishizawa, Masamue Oguri, Taira Oogi, Surhud More, Takahiro Nishimichi, Masahiro Nagashima, Yen-Ting Lin, Rachel Mandelbaum, Masahiro Takada, Neta Bahcall, Jean Coupon, Song Huang, Hung-Yu Jian, Yutaka Komiyama, Alexie Leauthaud, Lihwai Lin, Hironao Miyatake, Satoshi Miyazaki, Masayuki Tanaka
   Sep 2017
We present a statistical study of the redshift evolution of the cluster
galaxy population over a wide redshift range from 0.1 to 1.1, using Tex
optically-selected CAMIRA clusters from Tex~degTex of the Hyper
Suprime-Cam (HSC) Wide ...
Takahiro Nishimichi, Francis Bernardeau, Atsushi Taruya
Phys. Rev. D 96, 123515 (2017)      Aug 2017
We present numerical measurements of the power spectrum response function of
the gravitational growth of cosmic structures, defined as the functional
derivative of the nonlinear spectrum with respect to the linear counterpart,
based on Tex cos...
Cora Uhlemann, Enrico Pajer, Christophe Pichon, Takahiro Nishimichi, Sandrine Codis, Francis Bernardeau
   Aug 2017
Non-Gaussianities of dynamical origin are disentangled from primordial ones
using the formalism of large deviation statistics with spherical collapse
dynamics. This is achieved by relying on accurate analytical predictions for
the one-point probab...
Takahiro Nishimichi, Eugenio Noda, Marco Peloso, Massimo Pietroni
   Aug 2017
We study a new procedure to measure the sound horizon scale via Baryonic
Acoustic Oscillations (BAO). Instead of fitting the measured power spectrum
(PS) to a theoretical model containing the cosmological informations and all
the nonlinear effects...
Ryoma Murata, Takahiro Nishimichi, Masahiro Takada, Hironao Miyatake, Masato Shirasaki, Surhud More, Ryuichi Takahashi, Ken Osato
   Jul 2017
We constrain the scaling relation between optical richness (Tex) and
halo mass (Tex) for a sample of SDSS redMaPPer galaxy clusters within the
context of the {\it Planck} cosmological model. We use a forward modeling
approach where we model ...
Teppei Okumura, Takahiro Nishimichi, Keiichi Umetsu, Ken Osato
Phys. Rev. D 98, 023523 (2018)      Jun 2017
We investigate the effects of intrinsic alignments (IA) of dark-matter halo
shapes on cosmic density and velocity fields from cluster to cosmic scales
beyond 100 Mpc/h. Besides the density correlation function binned by the halo
orientation angle ...
Ryuichi Takahashi, Takashi Hamana, Masato Shirasaki, Toshiya Namikawa, Takahiro Nishimichi, Ken Osato, Kosei Shiroyama
ApJ, 850, 24, (2017)      Jun 2017
We present 108 full-sky gravitational lensing simulation data sets generated
by performing multiple-lens plane ray-tracing through high-resolution
cosmological Tex-body simulations. The data sets include full-sky convergence
and shear maps from re...
Daichi Suto, Sebastien Peirani, Yohan Dubois, Tetsu Kitayama, Takahiro Nishimichi, Shin Sasaki, Yasushi Suto
   Nov 2016
We characterize the non-sphericity of galaxy clusters by the projected axis
ratio of spatial distribution of star, dark matter, and X-ray surface
brightness (XSB). We select 40 simulated groups and clusters of galaxies with
mass larger than 5E13 M...
Masato Shirasaki, Takahiro Nishimichi, Baojiu Li, Yuichi Higuchi
   Oct 2016
We investigate the information content of various cosmic shear statistics on
the theory of gravity. Focusing on the Hu-Sawicki-type Tex model, we perform
a set of ray-tracing simulations and measure the convergence bispectrum, peak
counts and M...
Patrick Valageas, Atsushi Taruya, Takahiro Nishimichi
Phys. Rev. D 95, 023504 (2017)      Oct 2016
We investigate how the consistency relations of large-scale structures are
modified when the initial density field is not Gaussian. We consider both
scenarios where the primordial density field can be written as a nonlinear
functional of a Gaussia...
Daichi Suto, Tetsu Kitayama, Takahiro Nishimichi, Shin Sasaki, Yasushi Suto
   Aug 2016
We revisit the non-sphericity of cluster-mass scale halos from cosmological
N-body simulation on the basis of triaxial modelling. In order to understand
the difference between the simulation results and the conventional ellipsoidal
collapse model ...
Masato Shirasaki, Masahiro Takada, Hironao Miyatake, Ryuichi Takahashi, Takashi Hamana, Takahiro Nishimichi, Ryoma Murata
   Jul 2016
We develop a method to simulate galaxy-galaxy weak lensing by utilizing
all-sky, light-cone simulations and their inherent halo catalogs. Using the
mock catalog to study the error covariance matrix of galaxy-galaxy weak
lensing, we compare the ful...
Three-Dimensional Spatial Join Count Exploiting CPU Optimized STR R-Tree
Mitsuhashi Ryuya, Kawashima Hideyuku, Nishimichi Takahiro, Tatebe Osamu
2016 IEEE INTERNATIONAL CONFERENCE ON BIG DATA (BIG DATA)   2938-2947   2016   [Refereed]
Teppei Okumura, Chiaki Hikage, Tomonori Totani, Motonari Tonegawa, Hiroyuki Okada, Karl Glazebrook, Chris Blake, Pedro G. Ferreira, Surhud More, Atsushi Taruya, Shinji Tsujikawa, Masayuki Akiyama, Gavin Dalton, Tomotsugu Goto, Takashi Ishikawa, Fumihide Iwamuro, Takahiko Matsubara, Takahiro Nishimichi, Kouji Ohta, Ikkoh Shimizu, Ryuichi Takahashi, Naruhisa Takato, Naoyuki Tamura, Kiyoto Yabe, Naoki Yoshida
PASJ 68 (2016) 38      Nov 2015
We measure the redshift-space correlation function from a spectroscopic
sample of 2783 emission line galaxies from the FastSound survey. The survey,
which uses the Subaru Telescope and covers the redshift ranges of
Tex, is the first cosm...
Mélanie Habouzit, Marta Volonteri, Muhammad Latif, Takahiro Nishimichi, Sébastien Peirani, Yohan Dubois, Gary A. Mamon, Joseph Silk, Jacopo Chevallard
   Jul 2015
Quasars powered by massive black holes (BHs) with mass estimates above a
billion solar masses have been identified at redshift 6 and beyond. The
existence of such BHs requires almost continuous growth at the Eddington limit
for their whole lifetim...
Yong-Seon Song, Atsushi Taruya, Eric Linder, Kazuya Koyama, Cristiano G. Sabiu, Gong-Bo Zhao, Francis Bernardeau, Takahiro Nishimichi, Teppei Okumura
Phys. Rev. D 92, 043522 (2015)      Jul 2015
We analyse the clustering of cosmic large scale structure using a consistent
modified gravity perturbation theory, accounting for anisotropic effects along
and transverse to the line of sight. The growth factor has a particular scale
dependence in...
Takahiro Nishimichi, Patrick Valageas
Phys. Rev. D 92, 123510 (2015)      Mar 2015
We present the redshift-space generalization of the equal-time
angular-averaged consistency relations between Tex- and Tex-point
polyspectra of the cosmological matter density field. Focusing on the case of
Tex large-scale mode and Tex...
Toshiya Kashiwagi, Yasushi Suto, Atsushi Taruya, Issha Kayo, Takahiro Nishimichi, Kazuhiro Yahata
   Dec 2014
The most widely used Galactic extinction map (Schlegel, Finkbeiner, & Davis
1998, SFD) is constructed assuming that the observed FIR fluxes entirely come
from the Galactic dust. According to the earlier suggestion by Yahata et al.
(2007), we consi...
Takahiro Nishimichi, Francis Bernardeau, Atsushi Taruya
   Nov 2014
In order to infer the impact of the small-scale physics to the large-scale
properties of the universe, we use a series of cosmological Tex-body
simulations of self-gravitating matter inhomogeneities to measure, for the
first time, the response fun...
Jacopo Chevallard, Joseph Silk, Takahiro Nishimichi, Melanie Habouzit, Gary A. Mamon, Sébastien Peirani
   Oct 2014
[Abridged] Understanding how the intergalactic medium (IGM) was reionized at
z > 6 is one of the big challenges of current high redshift astronomy. It
requires modelling the collapse of the first astrophysical objects (Pop III
stars, first galaxie...
Atsushi Taruya, Takahiro Nishimichi, Francis Bernardeau, Takashi Hiramatsu, Kazuya Koyama
Phys. Rev. D 90, 123515 (2014)      Aug 2014
Based on the multi-point propagator expansion, we present resummed
perturbative calculations for cosmological power spectra and correlation
functions in the context of modified gravity. In a wide class of modified
gravity models that have a screen...
Mélanie Habouzit, Takahiro Nishimichi, Sébastien Peirani, Gary A. Mamon, Joseph Silk, Jacopo Chevallard
   Jul 2014
Primordial non-Gaussianities provide an important test of inflationary
models. Although the Planck CMB experiment has produced strong limits on
non-Gaussianity on scales of clusters, there is still room for considerable
non-Gaussianity on galactic...
Takahiro Nishimichi, Patrick Valageas
Phys. Rev. D 90, 023546 (2014)      Feb 2014
We explicitly test the equal-time consistency relation between the
angular-averaged bispectrum and the power spectrum of the matter density field,
employing a large suite of cosmological Tex-body simulations. This is the
lowest-order version of th...
Francis Bernardeau, Takahiro Nishimichi, Atsushi Taruya
   Dec 2013
An explicit full nulling scheme for cosmic shear observations is presented.
It makes possible the construction of shear maps from extended source
distributions for which the lens distance distribution is restricted to a
definite interval. Such a c...
Takahiro Nishimichi, Akira Oka
   Oct 2013
We model the apparent clustering anisotropy of Luminous Red Galaxies (LRGs)
in the Sloan Digital Sky Survey using subhalos identified in cosmological
Tex-body simulations. We first conduct a Markov-chain Monte Carlo analysis on
the parameters char...
Akira Oka, Shun Saito, Takahiro Nishimichi, Atsushi Taruya, Kazuhiro Yamamoto
MNRAS 439, 2515-2530 (2014)      Oct 2013
The anisotropic galaxy clustering on large scales provides us with a unique
opportunity to probe into the gravity theory through the redshift-space
distortions (RSDs) and the Alcock-Paczynski effect. Using the multipole power
spectra up to hexadec...
Takashi Ishikawa, Tomonori Totani, Takahiro Nishimichi, Ryuichi Takahashi, Naoki Yoshida, Motonari Tonegawa
   Aug 2013
Redshift space distortion (RSD) observed in galaxy redshift surveys is a
powerful tool to test gravity theories on cosmological scales, but the
systematic uncertainties must carefully be examined for future surveys with
large statistics. Here we e...
日本物理学会誌   68(6) 366-371,347   Jun 2013
Tsz Yan Lam, Fabian Schmidt, Takahiro Nishimichi, Masahiro Takada
PRD, 88, 023012 (2013)      May 2013
The comparison between dynamical mass and lensing mass provides a targeted
test for a wide range of modified gravity models. In our previous paper we
showed, through numerical simulations, that the measurement of the
line-of-sight velocity dispers...
Patrick Valageas, Takahiro Nishimichi, Atsushi Taruya
Phys. Rev. D, 87, 083522 (2013)      Feb 2013
We present a new approach to computing the matter density power spectrum,
from large linear scales to small highly nonlinear scales. Instead of
explicitly computing a partial series of high-order diagrams, as in
perturbative resummation schemes, w...
Masanori Sato, Takahiro Nishimichi
   Jan 2013
We study how well the Gaussian approximation is valid for computing the
covariance matrices of the convergence power and bispectrum in weak
gravitational lensing analyses. We focus on its impact on the cosmological
parameter estimations by compari...
Atsushi Taruya, Takahiro Nishimichi, Francis Bernardeau
   Jan 2013
Using a full implementation of resummed perturbation theory (PT) from a
multi-point propagator expansion, we put forward new theoretical predictions
for the two-point statistics of matter fluctuations in redshift space. The
predictions consistentl...
Yong-Seon Song, Takahiro Nishimichi, Atsushi Taruya, Issha Kayo
Phys. Rev. D 87, 123510 (2013)      Jan 2013
The cosmological power spectrum of the coherent matter flow is measured
exploiting an improved prescription for the apparent anisotropic clustering
pattern in redshift space. New statistical analysis is presented to provide an
optimal observationa...
Atsushi J. Nishizawa, Masahiro Takada, Takahiro Nishimichi
MNRAS 433, 209 (2013)      Dec 2012
We revisit an analytical model to describe the halo-matter cross-power
spectrum and the halo auto-power spectrum in the weakly nonlinear regime, by
combining the perturbation theory (PT) for matter clustering, the local bias
model, and the halo bi...
Francis Bernardeau, Atsushi Taruya, Takahiro Nishimichi
Phys. Rev. D 89, 023502 (2014)      Nov 2012
We explore the properties of two-point cosmic propagators when Perturbation
Theory (PT) loop corrections are consistently taken into account. We show in
particular how the interpolation scheme proposed in arXiv:1112.3895 can be
explicitly used up ...
Ryuichi Takahashi, Masanori Sato, Takahiro Nishimichi, Atsushi Taruya, Masamune Oguri
   Aug 2012
Based on a suite of state-of-the-art high-resolution Tex-body simulations, we
revisit the so-called halofit model (Smith et al. 2003) as an accurate fitting
formula for the nonlinear matter power spectrum. While the halofit model has
been frequent...
Atsushi Taruya, Francis Bernardeau, Takahiro Nishimichi, Sandrine Codis
   Aug 2012
We present a specific prescription for the calculation of cosmological power
spectra, exploited here at two-loop order in perturbation theory (PT), based on
the multi-point propagator expansion. In this approach power spectra are
constructed from ...
Masato Shirasaki, Naoki Yoshida, Takashi Hamana, Takahiro Nishimichi
   Apr 2012
We study the cosmological information contained in the Minkowski Functionals
(MFs) of weak gravitational lensing convergence maps. We show that the MFs
provide strong constraints on the local type primordial non-Gaussianity
parameter f_NL. We run ...
Takahiro Nishimichi
   Apr 2012
We investigate the clustering of halos in cosmological models starting with
general local-type non-Gaussian primordial fluctuations. We employ multiple
Gaussian fields and add local-type non-Gaussian corrections at arbitrary order
to cover a class...
Tsz Yan Lam, Takahiro Nishimichi, Fabian Schmidt, Masahiro Takada
Phys. Rev. Lett. 109, 051301 (2012)      Feb 2012
In General Relativity, the average velocity field of dark matter around
galaxy clusters is uniquely determined by the mass profile. The latter can be
measured through weak lensing. We propose a new method of measuring the
velocity field (phase spa...
Patrick Valageas, Masanori Sato, Takahiro Nishimichi
Astron. Astrophys. (2012), 541, A162      Dec 2011
We investigate the performance of an analytic model of the 3D matter
distribution, which combines perturbation theory with halo models, for
weak-lensing configuration-space statistics. We compared our predictions for
the weak-lensing convergence t...
Patrick Valageas, Masanori Sato, Takahiro Nishimichi
Astron. Astrophys. (2012), 541, A161      Nov 2011
We investigate the performance of an analytic model of the 3D matter
distribution, which combines perturbation theory with halo models, for
weak-lensing statistics. We compare our predictions for the weak-lensing
convergence power spectrum and bis...
Takahiro Nishimichi, Atsushi Taruya
Physical Review D vol. 84 (2011) Issue 4 id. 043526      Jun 2011
We measure the halo power spectrum in redshift space from cosmological N-body
simulations, and test the analytical models of redshift distortions
particularly focusing on the scales of baryon acoustic oscillations (BAOs).
Remarkably, the measured ...
Patrick Valageas, Takahiro Nishimichi
Astron.Astrophys. (2011), 532, A4      Feb 2011
We investigate how unified models should be built to be able to predict the
matter-density bispectrum (and power spectrum) from very large to small scales
and that are at the same time consistent with perturbation theory at low Tex
and with halo m...
Atsushi Taruya, Shun Saito, Takahiro Nishimichi
Phys.Rev.D83:103527,2011      Jan 2011
Baryon acoustic oscillations (BAOs) imprinted in the galaxy power spectrum
can be used as a standard ruler to determine angular diameter distance and
Hubble parameter at high redshift galaxies. Combining redshift distortion
effect which apparently...
Hajime Kawahara, Hiroshi Yoshitake, Takahiro Nishimichi, Thierry Sousbie
ApJ,727,L38 (2011)      Jan 2011
We report on a new merging group of galaxies, Suzaku J1552+2739 at z ~ 0.08
revealed by a SUZAKU observation. The group was found by observing a junction
of galaxy filaments optically identified in the Sloan Digital Sky Survey
spectroscopic data. ...
Patrick Valageas, Takahiro Nishimichi
Astron. Astrophys. (2011), 527, A87      Sep 2010
We investigate the building of unified models that can predict the
matter-density power spectrum and the two-point correlation function from very
large to small scales, being consistent with perturbation theory at low Tex and
with halo models at h...
Tsz Yan Lam, Takahiro Nishimichi, Naoki Yoshida
   Aug 2010
We study how primordial non-Gaussianity affects the pairwise velocity
probability density function (PDF) using an analytical model and cosmological
N-body simulations. We adopt the local type non-Gaussian models characterized
by f_{nl}, and examin...
Atsushi Taruya, Takahiro Nishimichi, Shun Saito
Phys.Rev.D82:063522,2010      Jun 2010
We present an improved prescription for matter power spectrum in redshift
space taking a proper account of both the non-linear gravitational clustering
and redshift distortion, which are of particular importance for accurately
modeling baryon acou...
Ryuichi Takahashi, Naoki Yoshida, Masahiro Takada, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Takahiro Nishimichi, Shun Saito, Atsushi Taruya
Astrophys.J.726:7,2011      Dec 2009
We study the sample variance of the matter power spectrum for the standard
Lambda Cold Dark Matter universe. We use a total of 5000 cosmological N-body
simulations to study in detail the distribution of best-fit cosmological
parameters and the bar...
Takahiro Nishimichi, Atsushi Taruya, Kazuya Koyama, Cristiano Sabiu
JCAP 1007:002, 2010      Nov 2009
We study the halo bispectrum from non-Gaussian initial conditions. Based on a
set of large Tex-body simulations starting from initial density fields with
local type non-Gaussianity, we find that the halo bispectrum exhibits a strong
dependence on ...
Hajime Takami, Takahiro Nishimichi, Katsuhiko Sato
   Oct 2009
We investigated the spatial correlation between the arrival directions of the
highest energy cosmic rays (HECRs) detected by the Akeno Giant Air Shower Array
(AGASA) with energies above Tex eV and the positions of galaxies
observed ...
Atsushi Taruya, Takahiro Nishimichi, Shun Saito, Takashi Hiramatsu
   Jun 2009
We study the non-linear evolution of baryon acoustic oscillations in the
matter power spectrum and correlation function from the improved perturbation
theory (PT). Based on the framework of renormalized PT, we apply the {\it
closure approximation}...
Hidenori Nomura, Kazuhiro Yamamoto, Gert Huetsi, Takahiro Nishimichi
Phys.Rev.D79:063512,2009      Mar 2009
We investigate the damping of the baryon acoustic oscillations in the matter
power spectrum due to the quasinonlinear clustering and redshift-space
distortions by confronting the models with the observations of the Sloan
Digital Sky Survey luminou...
Ryuichi Takahashi, Naoki Yoshida, Masahiro Takada, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Atsushi J. Nishizawa, Takahiro Nishimichi, Shun Saito, Atsushi Taruya
Astrophys.J.700:479-490,2009      Feb 2009
We use 5000 cosmological N-body simulations of 1(Gpc/h)^3 box for the
concordance LCDM model in order to study the sampling variances of nonlinear
matter power spectrum. We show that the non-Gaussian errors can be important
even on large length sc...
Hajime Takami, Takahiro Nishimichi, Kazuhiro Yahata, Katsuhiko Sato
JCAP 0906:031,2009      Dec 2008
We investigate correlation between the arrival directions of
ultra-high-energy cosmic rays (UHECRs) and the large-scale structure (LSS) of
the Universe by using statistical quantities which can find the angular scale
of the correlation. The Infrar...
Takahiro Nishimichi, Akihito Shirata, Atsushi Taruya, Kazuhiro Yahata, Shun Saito, Yasushi Suto, Ryuichi Takahashi, Naoki Yoshida, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Yipeng Jing, Kohji Yoshikawa
Publ. Astron. Soc. Japan 61, pp.321-332 (2009)      Oct 2008
We use a series of cosmological N-body simulations and various analytic
models to study the evolution of the matter power spectrum in real space in a
\Lambda Cold Dark Matter universe. We compare the results of N-body simulations
against three ana...
Hidenori Nomura, Kazuhiro Yamamoto, Takahiro Nishimichi
JCAP 0810:031,2008      Sep 2008
We investigate the damping of the baryon acoustic oscillations (BAO)
signature in the matter power spectrum due to the quasi-nonlinear clustering of
density perturbations. On the basis of the third order perturbation theory, we
construct a fitting...
Ryuichi Takahashi, Naoki Yoshida, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Takahiro Nishimichi, Akihito Shirata, Atsushi Taruya, Shun Saito, Kazuhiro Yahata, Yasushi Suto
   Feb 2008
We critically examine how well the evolution of large-scale density
perturbations is followed in cosmological Tex-body simulations. We first run a
large volume simulation and perform a mode-by-mode analysis in
three-dimensional Fourier space. We s...
Takahiro Nishimichi, Hiroshi Ohmuro, Masashi Nakamichi, Atsushi Taruya, Kazuhiro Yahata, Akihito Shirata, Shun Saito, Hidenori Nomura, Kazuhiro Yamamoto, Yasushi Suto
PASJ 59(2007) 1049      May 2007
An acoustic oscillation of the primeval photon-baryon fluid around the
decoupling time imprints a characteristic scale in the galaxy distribution
today, known as the baryon acoustic oscillation (BAO) scale. Several on-going
and/or future galaxy su...
Takahiro Nishimichi, Issha Kayo, Chiaki Hikage, Kazuhiro Yahata, Atsushi Taruya, Y. P. Jing, Ravi K. Sheth, Yasushi Suto
Publ.Astron.Soc.Jap.59:93,2007      Sep 2006
We consider nonlinear biasing models of galaxies with particular attention to
a correlation between linear and quadratic biasing coefficients, b_1 and b_2.
We first derive perturbative expressions for b_1 and b_2 in halo and peak
biasing models. T...

Conference Activities & Talks

大木平, 吉田直紀, 西道啓博, 日影千秋
日本天文学会年会講演予稿集   20 Aug 2018   
岡部泰三, 大栗真宗, 須藤靖, 西道啓博, 北山哲, 佐々木伸, PEIRANI Sebastien
日本天文学会年会講演予稿集   20 Aug 2018   
濱端亮成, 大栗真宗, 西道啓博
日本天文学会年会講演予稿集   20 Aug 2018   
樽家篤史, 西道啓博, JEONG Donghui
日本天文学会年会講演予稿集   20 Feb 2018   
高橋龍一, 西道啓博, 高田昌広, 白崎正人, 城山航誠
日本天文学会年会講演予稿集   20 Feb 2018