Articles
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06/17/2001--
06/17/2001
The [O III]4363 Emitting Region Obscured by Dusty Tori
The emission-line flux ratio of [O III]4363/[O III]5007 is a useful
diagnostic for the ionization mechanism and physical properties of narrow-line
regions in active galactic nuclei. However, it is known that simple
photoionization models underpredict this ratio. In this contribution, we report
on some pieces of evidence that a large fraction of the [O III]4363 emission
arises from the dense gas, which can be obscured by dusty tori. Taking this
dense component into account, we show that the flux ratio of [O III]4363/[O
III]5007 can be explained by two-component photoionization models.
Tohru Nagao
Takashi Murayama
Yoshiaki Taniguchi
12/13/2012--
11/30/2012
Correspondence between future-included and future-not-included theories
We briefly review the correspondence principle proposed in our previous
paper, which claims that if we regard a matrix element defined in terms of the
future state at time $T_B$ and the past state at time $T_A$ as an expectation
value in the complex action theory whose path runs over not only past but also
future, the expectation value at the present time $t$ of a future-included
theory for large $T_B-t$ and large $t-T_A$ corresponds to that of a
future-not-included theory with a proper inner product for large $t-T_A$. This
correspondence principle suggests that the future-included theory is not
excluded phenomenologically.
Keiichi Nagao
Holger Bech Nielsen
04/28/2023--
04/15/2022
A model explaining the new CDF II W boson mass linking to muon $g-2$ and dark matter
We propose a model to explain the W boson mass anomaly reported by the CDFII
collaboration that would suggest new physics (NP). We introduce exotic
fermions; one isospin doublet vector-like lepton, one isospin singlet
singly-charged vector-like lepton, and an isospin doublet inert scalar. The
proposed model provides sizable muon anomalous magnetic moment (muon $g-2$) due
to no chiral suppression and nonzero mass difference between the real and
imaginary parts of neutral inert scalar bosons. The inert scalar mass squared
difference and vector-like exotic leptons ($L', E'$ in the main text) affect
oblique parameters. Especially, the $T$-parameter shift from zero explains the
W boson mass anomaly. We search for the allowed parameter region to explain
both muon $g-2$ and W boson mass anomaly at the same time. We also discuss a
dark matter (DM) candidate assuming the real part of the inert scalar field to
be the one. We find that lighter DM mass is favored to be consistent with
experimental constraints.
Keiko I. Nagao
Takaaki Nomura
Hiroshi Okada
05/23/2012--
05/23/2012
Near-infrared spectroscopy of a nitrogen-loud quasar SDSS J1707+6443
We present near-infrared spectroscopy of the z=3.2 quasar SDSS J1707+6443,
obtained with MOIRCS on the Subaru Telescope. This quasar is classified as a
"nitrogen-loud" quasar because of the fairly strong NIII] and NIV]
semi-forbidden emission lines from the broad-line region (BLR) observed in its
rest-frame UV spectrum. However, our rest-frame optical spectrum from MOIRCS
shows strong [OIII] emission from the narrow-line region (NLR) suggesting that,
at variance with the BLR, NLR gas is not metal-rich. In order to reconcile
these contradictory results, there may be two alternative possibilities; (1)
the strong nitrogen lines from the BLR are simply due to a very high relative
abundance of nitrogen rather than to a very high BLR metallicity, or (2) the
BLR metallicity is not representative of the metallicity of the host galaxy,
better traced by the NLR. In either case, the strong broad nitrogen lines in
the UV spectrum are not indication of a chemically enriched host galaxy. We
estimated the black hole mass and Eddington ratio of this quasar from the
velocity width of both CIV and H_beta, that results in log(M_BH/M_sun) = 9.50
and log(L_bol/L_Edd) = -0.34. The relatively high Eddington ratio is consistent
with our earlier result that strong nitrogen emission from BLRs is associated
with high Eddington ratios. Finally, we detected significant [NeIII] emission
from the NLR, implying a quite high gas density of n~10^6 cm^-3 and suggesting
a strong coupling between quasar activity and dense interstellar clouds in the
host galaxy.
N. Araki
T. Nagao
K. Matsuoka
A. Marconi
R. Maiolino
H. Ikeda
T. Hashimoto
Y. Taniguchi
T. Murayama
06/14/2001--
06/14/2001
Spontaneous vortex phase in ErNi2B2C
Below T_{WFM} ~ 2.75K, a weak ferromagnetism and superconductivity coexist in
ErNi2B2C. In the present paper, a possibility of a spontaneous vortex phase was
examined directly by small angle neutron scattering technique. An external
magnetic field was applied to align ferromagnetic domains so that the internal
magnetic field induced by the weak ferromagnetism becomes uniform and uniaxial
over the bulk sample. When the field is removed, the flux line lattice
subsisted below T_{WFM} but disappeared above it. A pinning effect is also
discussed. We conclude that the spontaneous vortex state is realized in
ErNi2B2C.
H. Kawano-Furukawa
E. Habuta
T. Nagata
M. Nagao
H. Yoshizawa
N. Furukawa
H. Takeya
K. Kadowaki
05/09/2000--
05/09/2000
Massive random matrix ensembles at beta = 1 & 4 : QCD in three dimensions
The zero momentum sectors in effective theories of three dimensional QCD
coupled to pseudoreal (two colors) and real (adjoint) quarks in a classically
parity-invariant manner have alternative descriptions in terms of orthogonal
and symplectic ensembles of random matrices. Using this correspondence, we
compute finite-volume QCD partition functions and correlation functions of
Dirac operator eigenvalues in a presence of finite quark masses of the order of
the smallest Dirac eigenvalue. These novel correlation functions, expressed in
terms of quaternion determinants, are reduced to conventional results for the
Gaussian ensembles in the quenched limit.
T. Nagao
S. M. Nishigaki
02/18/2004--
02/18/2004
Commensurators of some non-uniform tree lattices and Moufang twin trees
Sh. Mozes showed that the commensurator of the lattice ${\rm PSL}_2
\bigl({\bf F}_p[t{}^{-1}] \bigr)$ is dense in the full automorphism group of
the Bruhat-Tits tree of valency $p+1$, the latter group being much bigger than
${\rm PSL}_2 \bigl({\bf F}_p((t)) \bigr)$. By G.A. Margulis' criterion, this
density is a generalized arithmeticity result. We show that the density of the
commensurator holds for many tree-lattices among those called of Nagao type by
H. Bass and A. Lubotzky. The result covers many lattices obtained via Moufang
twin trees.
Peter Abramenko
Bertrand Remy
02/15/2021--
04/16/2020
Framed motivic Donaldson-Thomas invariants of small crepant resolutions
For an arbitrary integer $r\geq 1$, we compute $r$-framed motivic PT and DT
invariants of small crepant resolutions of toric Calabi-Yau $3$-folds,
establishing a "higher rank" version of the motivic DT/PT wall-crossing
formula. This generalises the work of Morrison and Nagao. Our formulae, in
particular their relationship with the $r=1$ theory, fit nicely in the current
development of higher rank refined DT invariants.
Alberto Cazzaniga
Andrea T. Ricolfi
06/23/2019--
01/22/2019
Exact large deviation function of spin current for the one dimensional XX spin chain with domain wall initial condition
We investigate the fluctuations of the spin current for the one dimensional
XX spin chain starting from the domain wall initial condition. The generating
function of the current is shown to be written as a determinant with the Bessel
kernel. An exact analytical expression for the large deviation function is
obtained by applying the Coulomb gas method. Our results are also compared with
DMRG calculations.
H. Moriya
R. Nagao
T. Sasamoto
03/25/2016--
03/25/2016
Extinction Laws toward Stellar Sources within a Dusty Circimstellar Medium and Implications for Type Ia Supernovae
Many astronomical objects are surrounded by dusty environments. In such dusty
objects, multiple scattering processes of photons by circumstellar (CS) dust
grains can effectively alter extinction properties. In this paper, we
systematically investigate effects of multiple scattering on extinction laws
for steady-emission sources surrounded by the dusty CS medium, using a
radiation transfer simulation based on the Monte Carlo technique. In
particular, we focus on whether and how the extinction properties are affected
by properties of CS dust grains, adopting various dust grain models. We {\bf
confirm} that behaviors of the (effective) extinction laws are highly dependent
on the properties of CS grains. Especially, the total-to-selective extinction
ratio $R_{V}$, which characterizes the extinction law, can be either increased
or decreased, compared to the case without multiple scattering. We find that
the criterion for this behavior is given by a ratio of albedos in the $B$ and
$V$ bands. We also find that either small silicate grains or polycyclic
aromatic hydrocarbons (PAHs) are necessary for realizing a low value of $R_{V}$
as often measured toward Type Ia supernovae, if the multiple scattering by CS
dust is responsible for their non-standard extinction laws. Using the derived
relations between the properties of dust grains and the resulting effective
extinction laws, we propose that the extinction laws toward dusty objects could
be used to constrain the properties of dust grains in CS environments.
T. Nagao
K. Maeda
T. Nozawa
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