837 research outputs found
Non-linear Evolution of Baryon Acoustic Oscillations from Improved Perturbation Theory in Real and Redshift Spaces
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} that truncates the infinite series of loop contributions
at one-loop order, and obtain a closed set of integral equations for power
spectrum and non-linear propagator. The resultant integral expressions keep
important non-perturbative properties which can dramatically improve the
prediction of non-linear power spectrum. Employing the Born approximation, we
then derive the analytic expressions for non-linear power spectrum and the
predictions are made for non-linear evolution of baryon acoustic oscillations
in power spectrum and correlation function. A detailed comparison between
improved PT results and N-body simulations shows that a percent-level agreement
is achieved in a certain range in power spectrum and in a rather wider range in
correlation function. Combining a model of non-linear redshift-space
distortion, we also evaluate the power spectrum and correlation function in
correlation function. In contrast to the results in real space, the agreement
between N-body simulations and improved PT predictions tends to be worse, and a
more elaborate modeling for redshift-space distortion needs to be developed.
Nevertheless, with currently existing model, we find that the prediction of
correlation function has a sufficient accuracy compared with the
cosmic-variance errors for future galaxy surveys with volume of a few (Gpc/h)^3
at z>=0.5.Comment: 25 pages, 15 figures, accepted for publication in Phys.Rev.
Baryon Acoustic Oscillations in 2D: Modeling Redshift-space Power Spectrum from Perturbation Theory
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 acoustic oscillations (BAOs). Contrary to the models of
redshift distortion phenomenologically introduced but frequently used in the
literature, the new model includes the corrections arising from the non-linear
coupling between the density and velocity fields associated with two
competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God
effects. Based on the improved treatment of perturbation theory for
gravitational clustering, we compare our model predictions with monopole and
quadrupole power spectra of N-body simulations, and an excellent agreement is
achieved over the scales of BAOs. Potential impacts on constraining dark energy
and modified gravity from the redshift-space power spectrum are also
investigated based on the Fisher-matrix formalism. We find that the existing
phenomenological models of redshift distortion produce a systematic error on
measurements of the angular diameter distance and Hubble parameter by 1~2%, and
the growth rate parameter by ~5%, which would become non-negligible for future
galaxy surveys. Correctly modeling redshift distortion is thus essential, and
the new prescription of redshift-space power spectrum including the non-linear
corrections can be used as an accurate theoretical template for anisotropic
BAOs.Comment: 18 pages, 10 figure
Probing onset of strong localization and electron-electron interactions with the presence of direct insulator-quantum Hall transition
We have performed low-temperature transport measurements on a disordered
two-dimensional electron system (2DES). Features of the strong localization
leading to the quantum Hall effect are observed after the 2DES undergoes a
direct insulator-quantum Hall transition with increasing the perpendicular
magnetic field. However, such a transition does not correspond to the onset of
strong localization. The temperature dependences of the Hall resistivity and
Hall conductivity reveal the importance of the electron-electron interaction
effects to the observed transition in our study.Comment: 9 pages, 4 figure
Two-dimensional gapless spin liquids in frustrated SU(N) quantum magnets
A class of the symmetrically frustrated SU(N) models is constructed for
quantum magnets based on the generators of SU(N) group. The total Hamiltonian
lacks SU(N) symmtry. A mean field theory in the quasi-particle representation
is developed for spin liquid states. Numerical solutions in two dimension
indicate that the ground states are gapless and the quasi-particles are Dirac
particles. The mechanism may be helpful in exploring the spin liquid phases in
the spin-1 bilinear-biquadratic model and the spin-orbital model in higher
dimensions.Comment: 9 pages, 3 figures, to appear in New Journal of Physic
Pseudospin SU(2) Symmetry Breaking, Charge Density Wave and Superconductivity in the Hubbard Model
In this paper, we discuss physical consequences of pseudospin SU(2) symmetry
breaking in the negative-U Hubbard model at half-filling. If pseudospin
symmetry is spontaneously broken while its unique subgroup U(1) remains
invariant, it will lead to the charge density wave (CDW) ground state.
Furthermore, if the U(1) symmetry is also broken, the ground state will have
the off-diagonal long range order (ODLRO), signaling a superconductor. In this
case, CDW and superconductivity coexist to form a supersolid. Finally, we show
that CDW suppresses, but does not destroy superconductivity.Comment: 7 page
Role of Heat Shock Protein 70 in Induction of Stress Fiber Formation in Rat Arterial Endothelial Cells in Response to Stretch Stress
We investigated the mechanism by which endothelial cells (ECs) resist various forms of physical stress using an experimental system consisting of rat arterial EC sheets. Formation of actin stress fibers (SFs) and expression of endothelial heat-shock stress proteins (HSPs) in response to mechanical stretch stress were assessed by immunofluorescence microscopy. Stretch stimulation increased expression of HSPs 25 and 70, but not that of HSP 90. Treatment with SB203580, a p38 MAP kinase inhibitor that acts upstream of the HSP 25 activation cascade, or with geldanamycin, an inhibitor of HSP 90, had no effect on the SF formation response to mechanical stretch stress. In contrast, treatment with quercetin, an HSP 70 inhibitor, inhibited both upregulation of endothelial HSP 70 and formation of SFs in response to tensile stress. In addition, treatment of stretched ECs with cytochalasin D, which disrupts SF formation, did not adversely affect stretch-induced upregulation of endothelial HSP 70. Our data suggest that endothelial HSP 70 plays an important role in inducing SF formation in response to tensile stress
ALMA Fragmented Source Catalog in Orion (FraSCO). I. Outflow interaction within an embedded cluster in OMC-2/FIR 3, FIR 4, and FIR 5
Funding: This work was supported by NAOJ ALMA Scientific Research grant No. 2022-22B. The present study was supported by JSPS KAKENHI grants (JP17H06360, JP17K05387, JP17KK0096, JP21H00046, JP21K03617: MNM, 20K04034: SI). L.A.Z. acknowledges financial support from CONACyT-280775 and UNAM-PAPIIT IN110618 grants, México. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 851435).We present a high-angular resolution (∼1″) and wide-field ( 2.′9×1.′9 ) image of the 1.3 mm continuum, CO(J = 2–1) and SiO(J = 5–4) line emissions toward an embedded protocluster, FIR 3, FIR 4, and FIR 5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array. We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and H2 gas number densities are estimated to be 3.8 × 10−5–1.1 × 10−2 M⊙, 290–2000 au, and 6.4 × 106–3.3 × 108 cm−3, respectively. The results of a Jeans analysis show that ∼80% of the protostellar sources and ∼15% of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO(J = 2–1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO(J = 5–4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between dust condensation, FIR 4, and an energetic outflow driven by HOPS-370 located within FIR 3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star formation scenario in FIR 4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the N2H+ line.Publisher PDFPeer reviewe
ALMA Fragmented Source Catalogue in Orion (FraSCO) I. Outflow interaction within an embedded cluster in OMC-2/FIR3, FIR4, and FIR5
We present a high angular resolution () and wide-field () image of the 1.3-mm continuum, CO( = 2--1) line, and SiO( = 5--4)
line emissions toward an embedded protocluster, FIR3, FIR4, and FIR5, in the
Orion Molecular Cloud 2 obtained from the Atacama Large
Millimeter/submillimeter Array (ALMA). We identify 51 continuum sources, 36 of
which are newly identified in this study. Their dust masses, projected sizes,
and gas number densities are estimated to be --, 290--2000 au, and --, respectively. The
results of a Jeans analysis show that of the protostellar sources
and of the prestellar sources are gravitationally bound. We
identify 12 molecular outflows traced in the CO( = 2--1) emission, six of
which are newly detected. We spatially resolve shocked gas structures traced by
the SiO( = 5--4) emission in this region for the first time. We identify
shocked gas originating from outflows and other shocked regions. These results
provide direct evidence of an interaction between a dust condensation, FIR4,
and an energetic outflow driven by HOPS-370 located within FIR3. A comparison
of the outflow dynamical timescales, fragmentation timescales, and protostellar
ages shows that the previously proposed triggered star-formation scenario in
FIR4 is not strongly supported. We also discuss the spatial distribution of
filaments identified in our continuum image by comparing it with a previously
identified hub-fiber system in the line.Comment: 45 pages, 24 figures, 2 figure sets, 2 animations, Accepted for
publication in Ap
ALMA Fragmented Source Catalog in Orion (FraSCO). I. Outflow Interaction within an Embedded Cluster in OMC-2/FIR 3, FIR 4, and FIR 5
We present a high-angular resolution (∼1'') and wide-field () image of the 1.3 mm continuum, CO(J = 2–1) and SiO(J = 5–4) line emissions toward an embedded protocluster, FIR 3, FIR 4, and FIR 5, in the Orion Molecular Cloud 2 obtained from the Atacama Large Millimeter/submillimeter Array. We identify 51 continuum sources, 36 of which are newly identified in this study. Their dust masses, projected sizes, and H2 gas number densities are estimated to be 3.8 × 10−5–1.1 × 10−2 M⊙, 290–2000 au, and 6.4 × 106–3.3 × 108 cm−3, respectively. The results of a Jeans analysis show that ∼80% of the protostellar sources and ∼15% of the prestellar sources are gravitationally bound. We identify 12 molecular outflows traced in the CO(J = 2–1) emission, six of which are newly detected. We spatially resolve shocked gas structures traced by the SiO(J = 5–4) emission in this region for the first time. We identify shocked gas originating from outflows and other shocked regions. These results provide direct evidence of an interaction between dust condensation, FIR 4, and an energetic outflow driven by HOPS-370 located within FIR 3. A comparison of the outflow dynamical timescales, fragmentation timescales, and protostellar ages shows that the previously proposed triggered star formation scenario in FIR 4 is not strongly supported. We also discuss the spatial distribution of filaments identified in our continuum image by comparing it with a previously identified hub-fiber system in the N2H+ line
Equation of motion approach to the solution of Anderson model
Based on an equation of motion approach the single impurity Anderson
model(SIAM) is reexamined. Using the cluster expansions the equations of motion
of Green functions are transformed into the corresponding equations of motion
of connected Green functions, which provides a natural and uniform truncation
scheme. A factor of two missing in the Lacroix's approximation for the Kondo
temperature is gained in the next higher order truncation beyond Lacroix's. A
quantitative improvement in the density of states at the Fermi level is also
obtained.Comment: 4 pages, 2 figure
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