The cosmic microwave background (CMB) contains an anomalous cold spot with a
surrounding hot ring, known as the Cold Spot. Inoue & Silk (2006) proposed that
this feature could be explained by postulating a supervoid: if such a large
underdense reg...

The cosmic microwave background (CMB) has non-Gaussian features in the
temperature fluctuations. An anomalous cold spot surrounded with a hot ring,
called the Cold Spot is one of such features. If a large underdence region
(supervoid) resides towa...

We investigate anomalous strong lens systems, particularly the effects of
weak lensing by structures in the line of sight, in models with long-lived
electrically charged massive particles (CHAMPs). In such models, matter density
perturbations are ...

The Astrophysical Journal Letters (2017), 835, Number 2, L23
(published on Jan. 30) Jan 2017

We report the detection of a faint object with a flux of ~ 0.3
mJy, in the vicinity of the quadruply lensed QSO MG0414+0534 using the Atacama
Large Millimeter/submillimeter array (ALMA) Band 7. The object is most probably
a dusty dar...

By monitoring a large number of stars in the Local Group galaxies, we can
detect nanolensing events by sub-lunar mass compact objects (SULCOs) such as
primordial black holes (PBHs) and rogue (free-floating) dwarf planets in the
Milky Way halo. In ...

Physical Review. D. Covering Particles, Fields, Gravitation, and Cosmology 94(2,Pt.A) 023522.1‐023522.10 Jul 2016

Recently it has been claimed that the warm dark matter (WDM) model cannot at
the same time reproduce the observed Lyman-{\alpha} forests in distant quasar
spectra and solve the small-scale issues in the cold dark matter (CDM) model.
As an alternat...

MNRAS (April 11, 2016) Vol. 457 2936-2950 First published online
February 17, 2016 Oct 2015

We present an analysis of the ALMA long baseline science verification data of
the gravitational lens system SDP.81. We fit the positions of the brightest
clumps at redshift z=3.042 and a possible AGN component of the lensing galaxy
at redshift z=0...

We explore the weak lensing effects by ministructures in the line-of-sight in
a quadruply lensed quasar MG0414+0534 that shows an anomaly in the flux-ratios.
We find that the observed flux-ratio anomaly can be explained by a presence of
either a m...

MNRAS, Vol. 447, Issue 2, p.1452-1459 (2015) Oct 2014

We explore the weak lensing effects by ministructures in the line-of-sight in
a quadruply lensed quasar MG0414+0534 that shows an anomaly in the flux-ratios.
We find that the observed flux-ratio anomaly can be explained by a presence of
either a m...

We investigate the weak lensing effect by line-of-sight structures with a
surface mass density of <~10^8 solar mass/arcsec^2 in QSO-galaxy quadruple lens
systems. Using high-resolution N-body simulations in warm dark matter (WDM)
models and observ...

MNRAS (April 11, 2015) 448 (3): 2704-2716. First published online
March 9, 2015 Sep 2014

We investigate the weak lensing effect by line-of-sight structures with a
surface mass density of <~10^8 solar mass/arcsec^2 in QSO-galaxy quadruple lens
systems. Using high-resolution N-body simulations in warm dark matter (WDM)
models and observ...

We investigate the weak lensing effects of line-of-sight structures on
quadruple images in quasar-galaxy strong lens systems based on N-body and
ray-tracing simulations that can resolve halos with a mass of 10^5 solar mass.
The intervening halos a...

We investigate the weak lensing effects of line-of-sight structures on
quadruple images in quasar-galaxy strong lens systems based on N-body and
ray-tracing simulations that can resolve halos with a mass of 10^5 solar mass.
The intervening halos a...

Missing fluctuations in masked regions in the sky can be reconstructed from
fluctuations in the surrounding unmasked regions if they are sufficiently
smooth. We propose to reconstruct such missing fluctuations by iteratively
applying a spherical h...

MNRAS (October 11, 2016) 462 (1): 588-600 May 2013

In the cosmic microwave background or galaxy density maps, missing
fluctuations in masked regions can be reconstructed from fluctuations in the
surrounding unmasked regions if the original fluctuations are sufficiently
smooth. One reconstruction m...

A galaxy halo may contain a large number of intermediate mass black holes
(IMBHs) with masses in the range of 10^{2-6} solar mass. We propose to directly
detect these IMBHs by observing multiply imaged QSO-galaxy or galaxy-galaxy
strong lens syste...

We explore the weak lensing effect by line-of-sight halos and sub-halos with
a mass of M < 10^7 solar mass in QSO-galaxy strong lens systems with quadruple
images in a concordant LCDM universe. Using a polynomially fitted non-linear
power spectrum...

In a concordant Cold Dark Matter (CDM) model, large-angle
Cosmic Microwave Background (CMB) temperature anisotropy due to linear
perturbations in the local universe is not negligible. We explore a possible
role of an underdense ...

Recent measurements of hot and cold spots on the cosmic microwave background
(CMB) sky suggest a presence of super-structures on (>100 h^{-1}Mpc) scales. We
develop a new formalism to estimate the expected amplitude of temperature
fluctuations due...

We present mid-infrared imaging at 11.7 m for the quadruple lens
systems, MG0414+0534 and Q2237+030, using the cooled mid-infrared camera and
spectrometer (COMICS) attached on the Subaru telescope. MG0414+0534 is
characterized by a bright pai...

Recent observational data of supernovae indicate that we may live in an
underdense region, which challenges the Copernican principle. We show that the
integrated Sachs-Wolfe (ISW) effect is an excellent discriminator between
anti-Copernican inhomo...

We study the cosmic microwave background (CMB) anisotropy due to spherically
symmetric nonlinear structures in flat universes with dust and a cosmological
constant. By modeling a time-evolving spherical compensated void/lump by
Lemaitre-Tolman-Bon...

We develop a new interpolation scheme, based on harmonic inpainting, for
reconstructing the cosmic microwave background temperature data within the
Galaxy mask from the data outside the mask. We find that, for scale-invariant
isotropic random Gaus...

Hierarchical clustering models of cold dark matter (CDM) predict that about
5% - 10% of a galaxy-sized halo with mass ~ 10^12 solar masses (M_sun) resides
in substructures (CDM subhalos) with masses <= 10^8 M_sun. To directly identify
such substru...

We study second order gravitational effects of local inhomogeneities on the
cosmic microwave background radiation in flat universes with matter and a
cosmological constant . We find that the general relativistic
correction to the Newtonia...

Science and Technology No.19 p 11-14 RIST, Kinki University (2007) Oct 2007

It has been argued that the large-angle cosmic microwave background
anisotropy has anomalies at 3-sigma level. We review various proposed ideas to
explain the origin of the anomalies and discuss how we can constrain the
proposed models using futur...

We explore the large angular scale temperature anisotropies in the cosmic
microwave background (CMB) due to homogeneous local dust-filled voids in a flat
Friedmann-Robertson-Walker universe with a cosmological constant. In comparison
with the equi...

We propose to observe QSO-galaxy strong lens systems to give a new constraint
on the damping scale of the initial fluctuations. We find that the future
observation of submilliarc scale astrometric shifts of the multiple lensed
images of QSOs would...

We explore the large angular scale temperature anisotropies in the cosmic
microwave background due to expanding homogeneous local voids at redshift z~1.
A compensated spherically symmetric homogeneous dust-filled void with radius
\~3*10^2 h^{-1}Mp...

Annual reports by Research Institute for Science and Technology, (2006) 18, p.11-14 Dec 2005

A galaxy-sized halo may contain a large number of intermediate mass (10^{2-4}
solar mass) compact objects (IMCOs), which can be intermediate mass black holes
(IMBHs) or the CDM subhalos. We propose to directly detect the IMBHs by
observing multipl...

We present mid-infrared imaging at 11.7 mu m for the quadruple lens systems,
PG1115+080 and B1422+231, using the cooled mid-infrared camera and spectrometer
(COMICS) attached on the Subaru telescope. These lensed QSOs are characterized
by their an...

The cold dark matter (CDM) structure formation model predicts that about 5-10
percent of a typical galactic halo of mass is in
substructures with masses . To directly detect such
substructures, we propose to o...

We investigate the extended source size effects on gravitational lensing in
which a lens consists of a smooth potential and small mass clumps
(``substructure lensing''). We first consider a lens model that consists of a
clump modeled as a singular...

A significant fraction of non-baryonic or baryonic dark matter in galactic
halos may consist of MASsive Compact Objects (MASCOs) with mass
M=10^{1-4}M_{sun}. Possible candidates for such compact objects include
primordial black holes or remnants o...

In many braneworld models, gravity is largely modified at the electro-weak
scale ~ 1TeV. In such models, primordial black holes (PBHs) with lunar mass M ~
10^{-7}M_sun might have been produced when the temperature of the universe was
at ~ 1TeV. If...

We reexamine constraints on the spatial size of closed toroidal models with
cold dark matter and the cosmological constant from cosmic microwave
background. We carry out Bayesian analyses using the Cosmic Background Explorer
(COBE) data properly t...

We revisit the cloud-in-cloud problem for non-Gaussian density fluctuations.
We show that the extended Press-Schechter (EPS) formalism for non-Gaussian
fluctuations has a flaw in describing mass functions regardless of type of
filtering. As an exa...

We study the effect of global topology of the spatial geometry on the cosmic
microwave background (CMB) for closed flat and closed hyperbolic models in
which the spatial hypersurface is multiply connected. If the CMB temperature
fluctuations were ...

We revisit the observational constraints on compact(closed) hyperbolic(CH)
models from cosmic microwave background(CMB). We carry out Bayesian analyses
for CH models with volume comparable to the cube of the present curvature
radius using the COBE...

We have investigated the cosmic microwave background (CMB) anisotropy in
closed multiply connected universes
(flat and hyperbolic) with low matter density. We show that the COBE
constraints on these low matter density models with non-trivial topo...

In this paper, the cosmic microwave background (CMB) anisotropy in a
multiply-connected compact flat 3-torus model with the cosmological constant is
investigated. Using the COBE-DMR 4-year data, a full Bayesian analysis revealed
that the constrain...

In this paper, we numerically investigate the length spectra and the
low-lying eigenvalue spectra of the Laplace-Beltrami operator for a large
number of small compact(closed) hyperbolic (CH) 3-manifolds. The first non-zero
eigenvalues have been su...

In this paper, Gaussianity of eigenmodes and non-Gaussianity in the Cosmic
Microwave Background (CMB) temperature fluctuations in two smallest compact
hyperbolic (CH) models are investigated. First, it is numerically found that
the expansion coeff...

The effect of a non-trivial topology on the temperature correlations on the
cosmic microwave background (CMB) in a small compact hyperbolic universe with
volume comparable to the cube of the curvature radius is investigated. Because
the bulk of la...

Measurements of CMB anisotropy are ideal experiments for discovering the
non-trivial global topology of the universe. To evaluate the CMB anisotropy in
multiply-connected compact cosmological models, one needs to compute eigenmodes
of the Laplace-...

Measurements of cosmic microwave background (CMB) anisotropy are ideal
experiments for discovering the non-trivial global topology of the universe. To
evaluate the CMB anisotropy in multiply-connected compact cosmological models,
one needs to comp...

Anton T. Jaelani, Anupreeta More, Alessandro Sonnenfeld, Masamune Oguri, Cristian E. Rusu, Kenneth C. Wong, James H. H. Chan, Sherry H. Suyu, Issha Kayo, Chien-Hsiu Lee, Kaiki T. Inoue

Aug 2019

We report a serendipitous discovery of HSC J0904--0102, a quadruply lensed
Lyman Break Galaxy (LBG) in the Survey of Gravitationally Lensed Objects in
Hyper Suprime-Cam Imaging (SuGOHI). Owing to its point-like appearance, the
source was thought t...

To set useful limits on the abundance of small-scale dark matter halos
(subhalos) in a galaxy scale, we have carried out mid-infrared imaging and
integral-field spectroscopy for a sample of quadruple lens systems showing
anomalous flux ratios. The...

Motohiro Enoki, Kaiki T. Inoue, Masahiro Nagashima, Naoshi Sugiyama

Feb 2005

We investigate the expected gravitational wave emission from coalescing
supermassive black hole (SMBH) binaries resulting from mergers of their host
galaxies. We employ a semi-analytic model of galaxy and quasar formation based
on the hierarchical...

Motohiro Enoki, Kaiki T. Inoue, Masahiro Nagashima, Naoshi Sugiyama

Astrophys.J. 615 (2004) 19 Apr 2004

We investigate the expected gravitational wave emission from coalescing
supermassive black hole (SMBH) binaries resulting from mergers of their host
galaxies. When galaxies merge, the SMBHs in the host galaxies sink to the
center of the new merged...

We find that the evolution of gravitational potential of super-structures in accelerating universes plays an important role as a cause of claimed anomalies in the large-angle cosmic microwave background temperature anisotropy. In particular, the e...