220 research outputs found
Accretion Disk Spectra of the Ultra-luminous X-ray Sources in Nearby Spiral Galaxies and Galactic Superluminal Jet Sources
Ultra-luminous Compact X-ray Sources (ULXs) in nearby spiral galaxies and
Galactic superluminal jet sources share the common spectral characteristic that
they have unusually high disk temperatures which cannot be explained in the
framework of the standard optically thick accretion disk in the Schwarzschild
metric. On the other hand, the standard accretion disk around the Kerr black
hole might explain the observed high disk temperature, as the inner radius of
the Kerr disk gets smaller and the disk temperature can be consequently higher.
However, we point out that the observable Kerr disk spectra becomes
significantly harder than Schwarzschild disk spectra only when the disk is
highly inclined. This is because the emission from the innermost part of the
accretion disk is Doppler-boosted for an edge-on Kerr disk, while hardly seen
for a face-on disk. The Galactic superluminal jet sources are known to be
highly inclined systems, thus their energy spectra may be explained with the
standard Kerr disk with known black hole masses. For ULXs, on the other hand,
the standard Kerr disk model seems implausible, since it is highly unlikely
that their accretion disks are preferentially inclined, and, if edge-on Kerr
disk model is applied, the black hole mass becomes unreasonably large (> 300
M_solar). Instead, the slim disk (advection dominated optically thick disk)
model is likely to explain the observed super-Eddington luminosities, hard
energy spectra, and spectral variations of ULXs. We suggest that ULXs are
accreting black holes with a few tens of solar mass, which is not unexpected
from the standard stellar evolution scenario, and that their X-ray emission is
from the slim disk shining at super-Eddington luminosities.Comment: ApJ, accepte
Does the Slim-Disk Model Correctly Consider Photon-Trapping Effects?
We investigate the photon-trapping effects in the super-critical black hole
accretion flows by solving radiation transfer as well as the energy equations
of radiation and gas. It is found that the slim-disk model generally
overestimates the luminosity of the disk at around the Eddington luminosity
(L_E) and is not accurate in describing the effective temperature profile,
since it neglects time delay between energy generation at deeper inside the
disk and energy release at the surface. Especially, the photon-trapping effects
are appreciable even below L ~ L_E, while they appear above ~ 3L_E according to
the slim disk. Through the photon-trapping effects, the luminosity is reduced
and the effective temperature profile becomes flatter than r^{-3/4} as in the
standard disk. In the case that the viscous heating is effective only around
the equatorial plane, the luminosity is kept around the Eddington luminosity
even at very large mass accretion rate, Mdot>>L_E/c^2. The effective
temperature profile is almost flat, and the maximum temperature decreases in
accordance with rise in the mass accretion rate. Thus, the most luminous radius
shifts to the outer region when Mdot/(L_E/c^2) >> 10^2. In the case that the
energy is dissipated equally at any heights, the resultant luminosity is
somewhat larger than in the former case, but the energy-conversion efficiency
still decreases with increase of the mass accretion rate, as well. The most
luminous radius stays around the inner edge of the disk in the latter case.
Hence, the effective temperature profile is sensitive to the vertical
distribution of energy production rates, so is the spectral shape. Future
observations of high L/L_E objects will be able to test our model.Comment: 10 pages, 7 figures, accepted for publication in Ap
The Nature of Ultra-Luminous Compact X-Ray Sources in Nearby Spiral Galaxies
Studies were made of ASCA spectra of seven ultra-luminous compact X-ray
sources (ULXs) in nearby spiral galaxies; M33 X-8 (Takano et al. 1994), M81 X-6
(Fabbiano 1988b; Kohmura et al. 1994; Uno 1997), IC 342 Source 1 (Okada et al.
1998), Dwingeloo 1 X-1 (Reynolds et al. 1997), NGC 1313 Source B (Fabbiano &
Trinchieri 1987; Petre et al. 1994), and two sources in NGC 4565 (Mizuno et al.
1999). With the 0.5--10 keV luminosities in the range 10^{39-40} ergs/s, they
are thought to represent a class of enigmatic X-ray sources often found in
spiral galaxies. For some of them, the ASCA data are newly processed, or the
published spectra are reanalyzed. For others, the published results are quoted.
The ASCA spectra of all these seven sources have been described successfully
with so called multi-color disk blackbody (MCD) emission arising from
optically-thick standard accretion disks around black holes. Except the case of
M33 X-8, the spectra do not exhibit hard tails. For the source luminosities not
to exceed the Eddington limits, the black holes are inferred to have rather
high masses, up to ~100 solar masses. However, the observed innermost disk
temperatures of these objects, Tin = 1.1--1.8 keV, are too high to be
compatible with the required high black-hole masses, as long as the standard
accretion disks around Schwarzschild black holes are assumed. Similarly high
disk temperatures are also observed from two Galactic transients with
superluminal motions, GRO 1655-40 and GRS 1915+105. The issue of unusually high
disk temperature may be explained by the black hole rotation, which makes the
disk get closer to the black hole, and hence hotter.Comment: submitted to ApJ, December 199
and processes with polarized muons and supersymmetric grand unified theories
and processes are
analyzed in detail with polarized muons in supersymmetric grand unified
theories. We first present Dalitz plot distribution for decay based on effective Lagrangian with general
lepton-flavor-violating couplings and define various P- and T-odd asymmetries.
We calculate branching ratios and asymmetries in supersymmetric SU(5) and
SO(10) models taking into account complex soft supersymmetry breaking terms.
Imposing constraints from experimental bounds on the electron, neutron and
atomic electric dipole moments, we find that the T-odd asymmetry for can be 15% in the SU(5) case. P-odd asymmetry with respect
to muon polarization for varies from -20% to -100%
for the SO(10) model while it is in the SU(5) case. We also show that
the P-odd asymmetries in and the ratio of
and branching
fractions are useful to distinguish different models.Comment: 52 pages, 15 figure
Scherk-Schwarz Supersymmetry Breaking for Quasi-localized Matter Fields and Supersymmetry Flavor Violation
We examine the soft supersymmetry breaking parameters induced by the
Scherk-Schwarz (SS) boundary condition in 5-dimensional orbifold field theory
in which the quark and lepton zero modes are quasi-localized at the orbifold
fixed points to generate the hierarchical Yukawa couplings. In such theories,
the radion corresponds to a flavon to generate the flavor hierarchy and at the
same time plays the role of the messenger of supersymmetry breaking. As a
consequence, the resulting soft scalar masses and trilinear -parameters of
matter zero modes at the compactification scale are highly flavor-dependent,
thereby can lead to dangerous flavor violations at low energy scales. We
analyze in detail the low energy flavor violations in SS-dominated
supersymmetry breaking scenario under the assumption that the compactification
scale is close to the grand unification scale and the 4-dimensional effective
theory below the compactification scale is given by the minimal supersymmetric
standard model. Our analysis can be applied to any supersymmetry breaking
mechanism giving a sizable -component of the radion superfield, e.g. the
hidden gaugino condensation model.Comment: revtex4, 22 pages, some numerical errors are corrected in
phenomenological analysis, main conclusion does not chang
A comprehensive survey on quantum computer usage: How many qubits are employed for what purposes?
Quantum computers (QCs), which work based on the law of quantum mechanics,
are expected to be faster than classical computers in several computational
tasks such as prime factoring and simulation of quantum many-body systems. In
the last decade, research and development of QCs have rapidly advanced. Now
hundreds of physical qubits are at our disposal, and one can find several
remarkable experiments actually outperforming the classical computer in a
specific computational task. On the other hand, it is unclear what the typical
usages of the QCs are. Here we conduct an extensive survey on the papers that
are posted in the quant-ph section in arXiv and claim to have used QCs in their
abstracts. To understand the current situation of the research and development
of the QCs, we evaluated the descriptive statistics about the papers, including
the number of qubits employed, QPU vendors, application domains and so on. Our
survey shows that the annual number of publications is increasing, and the
typical number of qubits employed is about six to ten, growing along with the
increase in the quantum volume (QV). Most of the preprints are devoted to
applications such as quantum machine learning, condensed matter physics, and
quantum chemistry, while quantum error correction and quantum noise mitigation
use more qubits than the other topics. These imply that the increase in QV is
fundamentally relevant, and more experiments for quantum error correction, and
noise mitigation using shallow circuits with more qubits will take place.Comment: 14 pages, 5 figures, figures regenerate
Muon anomalous magnetic moment, lepton flavor violation, and flavor changing neutral current processes in SUSY GUT with right-handed neutrino
Motivated by the large mixing angle solutions for the atmospheric and solar
neutrino anomalies, flavor changing neutral current processes and lepton flavor
violating processes as well as the muon anomalous magnetic moment are analyzed
in the framework of SU(5) SUSY GUT with right-handed neutrino. In order to
explain realistic mass relations for quarks and leptons, we take into account
effects of higher dimensional operators above the GUT scale. It is shown that
the supersymmetric (SUSY) contributions to the CP violation parameter in
mixing, , the branching ratio,
and the muon anomalous magnetic moment become large in a wide range of
parameter space. We also investigate correlations among these quantities.
Within the current experimental bound of , large
SUSY contributions are possible either in the muon anomalous magnetic moment or
in . In the former case, the favorable value of the recent muon
anomalous magnetic moment measurement at the BNL E821 experiment can be
accommodated. In the latter case, the allowed region of the Kobayashi-Maskawa
phase can be different from the prediction within the Standard Model (SM) and
therefore the measurements of the CP asymmetry of mode and
could discriminate this case from the SM. We also show that
the branching ratio can be close to the current
experimental upperbound and the mixing induced CP asymmetry of the radiative B
decay can be enhanced in the case where the neutrino parameters correspond to
the Mikheyev-Smirnov-Wolfenstein small mixing angle solution.Comment: 70 pages, 14 figure
Induction of human regulatory innate lymphoid cells from group 2 innate lymphoid cells by retinoic acid
BACKGROUND: Group 2 innate lymphoid cells (ILC2s) play critical roles in induction and exacerbation of allergic airway inflammation. Thus, clarification of the mechanisms that underlie the regulation of ILC2 activation has received significant attention. Although ILCs are divided into three major subsets that mirror helper effector T-cell subsets, counterpart subsets of regulatory T (Treg) cells have not been well characterized.
OBJECTIVE: We sought to determine the factors that induce regulatory ILCs (ILCregs).
METHODS: IL-10+ ILCregs induced from ILC2s by retinoic acid (RA) were analyzed using RNA-sequencing and flow cytometry. ILCregs were evaluated in human nasal tissues from healthy individuals and patients with chronic rhinosinusitis with nasal polyp (CRSwNP), and in lung tissues from house dust mite (HDM)- or saline-treated mice.
RESULTS: RA induced IL-10 secretion by human ILC2s, but not type-2 cytokines. IL-10+ ILCregs, converted from ILC2s by RA stimulation, expressed a Treg-like signature with the expression of IL-10, CTLA-4 and CD25, with down regulated effector type 2-related markers such as CRTH-2 and ST2, and suppressed activation of CD4+ T cells and ILC2s. ILCregs were rarely detected in human nasal tissue from healthy individuals or lung tissues from saline-treated mice, but were increased in nasal tissues from patients with CRSwNP and in lung tissues from HDM-treated mice. Enzymes for RA synthesis were up-regulated in airway epithelial cells during type-2 inflammation in vivo and by IL-13 in vitro.
CONCLUSION: We have identified a unique immune regulatory and anti-inflammatory pathway by which RA converts ILC2s to ILCregs. Interactions between airway epithelial cells and ILC2s play an important roles in the generation of ILCregs
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