927 research outputs found
Three-dimensional Black Holes and Liouville Field Theory
A quantization of (2+1)-dimensional gravity with negative cosmological
constant is presented and quantum aspects of the (2+1)-dimensional black holes
are studied thereby. The quantization consists of two procedures. One is
related with quantization of the asymptotic Virasoro symmetry. A notion of the
Virasoro deformation of 3-geometry is introduced. For a given black hole, the
deformation of the exterior of the outer horizon is identified with a product
of appropriate coadjoint orbits of the Virasoro groups .
Its quantization provides unitary irreducible representations of the Virasoro
algebra, in which state of the black hole becomes primary. To make the
quantization complete, holonomies, the global degrees of freedom, are taken
into account. By an identification of these topological operators with zero
modes of the Liouville field, the aforementioned unitary representations
reveal, as far as , as the Hilbert space of this two-dimensional
conformal field theory. This conformal field theory, living on the cylinder at
infinity of the black hole and having continuous spectrums, can recognize the
outer horizon only as a it one-dimensional object in and
realize it as insertions of the corresponding vertex operator. Therefore it can
not be a conformal field theory on the horizon. Two possible descriptions of
the horizon conformal field theory are proposed.Comment: 39 pages, LaTeX, 8 figures are added. Section 4.3 is revised and
enlarged to include the case of conical singularities. Several typos are
corrected. References are adde
Detection of Dark Matter Concentrations in the Field of Cl 1604+4304 from Weak Lensing Analysis
We present a weak-lensing analysis of a region around the galaxy cluster Cl
1604+4304 (z=0.897) on the basis of the deep observations with the HST/WFPC2.
We apply a variant of Schneider's aperture mass technique to the observed WFPC2
field and obtain the distribution of weak-lensing signal-to-noise (S/N) ratio
within the field. The resulting S/N map reveals a clear pronounced peak located
about 1.7 arcmin (850h_{50}^{-1} kpc at z=0.897) southwest of the second peak
associated with the optical cluster center determined from the dynamical
analysis of Postman et al. A non-linear finite-field inversion method has been
used to reconstruct the projected mass distribution from the observed shear
field. The reconstructed mass map shows a super-critical feature at the
location of the S/N peak as well as in the cluster central region. Assuming the
redshift distribution of field galaxies, we obtain the total mass in the
observed field to be 1.0 h_{50}^{-1} 10^{15} M_sun for =1.0. The estimated
mass within a circular aperture of radius 280h_{50}^{-1} kpc centered on the
dark clump is 2.4h_{50}^{-1} 10^{14} M_sun. We have confirmed the existence of
the ` dark ' mass concentration from another deep HST observation with a
slightly different ~20 arcsec pointing.Comment: 7 pages, 3 figure
Recommended from our members
Oral Immunotherapy for Food Allergy: Towards a New Horizon
Food allergy has increased dramatically in prevalence over the past decade in westernized countries, and is now a major public health problem. Unfortunately for patients with food allergy, there is no effective therapy beyond food allergen avoidance, and rapid medical treatment for accidental exposures. Recently, oral immunotherapy (OIT) has been investigated as a treatment for this problem. In this review, we will discuss the progress in developing OIT for food allergy, including a novel approach utilizing Xolair (anti-IgE monoclonal antibody, omalizumab) in combination with OIT. This combination may enhance both the safety and efficacy of oral immunotherapy, and could lead to a widely available and safe therapy for food allergy
Three-dimensional multi-probe analysis of the galaxy cluster A1689
arXiv:1503.01482v2.-- et al.We perform a three-dimensional multi-probe analysis of the rich galaxy cluster A1689, one of the most powerful known lenses on the sky, by combining improved weak-lensing data from new wide-field Subaru/Suprime-Cam observations with strong-lensing, X-ray, and Sunyaev–Zel'dovich effect (SZE) data sets. We reconstruct the projected matter distribution from a joint weak-lensing analysis of two-dimensional shear and azimuthally integrated magnification constraints, the combination of which allows us to break the mass-sheet degeneracy. The resulting mass distribution reveals elongation with an axis ratio of ~0.7 in projection, aligned well with the distributions of cluster galaxies and intracluster gas. When assuming a spherical halo, our full weak-lensing analysis yields a projected halo concentration of (), consistent with and improved from earlier weak-lensing work. We find excellent consistency between independent weak and strong lensing in the region of overlap. In a parametric triaxial framework, we constrain the intrinsic structure and geometry of the matter and gas distributions, by combining weak/strong lensing and X-ray/SZE data with minimal geometric assumptions. We show that the data favor a triaxial geometry with minor–major axis ratio 0.39±0.15 and major axis closely aligned with the line of sight (22°±10°). We obtain a halo mass and a halo concentration , which overlaps with the tail of the predicted distribution. The shape of the gas is rounder than the underlying matter but quite elongated with minor–major axis ratio 0.60 ± 0.14. The gas mass fraction within 0.9 Mpc is , a typical value for high-mass clusters. The thermal gas pressure contributes to ~60% of the equilibrium pressure, indicating a significant level of non-thermal pressure support. When compared to Planck's hydrostatic mass estimate, our lensing measurements yield a spherical mass ratio of MPlanck/MGL = 0.70 ± 0.15 and 0.58 ± 0.10 with and without corrections for lensing projection effects, respectively.The work is partially supported by the Ministry of Science and Technology of Taiwan under the grant MOST 103-2112-M-001-030-MY3. M. S. acknowledges financial contributions from contracts ASI/INAF I/023/12/0, by the PRIN MIUR 2010–2011 “The dark universe and the cosmic evolution of baryons: from current surveys to Euclid” and by the PRIN INAF 2012 “The universe in the box: multiscale simulations of cosmic structure.” M. N. acknowledges financial support from PRIN INAF 2014. J. M. D. acknowledges support of the consolider project CSD2010-00064 and AYA2012-39475-C02-01 funded by the Ministerio de Economia y Competitividad. N. O. is supported
by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (26800097). This work was partially supported by “World Premier International Research Center Initiative (WPI Initiative)” and the Funds for the Development of Human Resources in Science and Technology under MEXT, Japan.Peer Reviewe
Hawking Fluxes, Back reaction and Covariant Anomalies
Starting from the chiral covariant effective action approach of Banerjee and
Kulkarni [Phys. Lett. B 659, 827(2008)], we provide a derivation of the Hawking
radiation from a charged black hole in the presence of gravitational back
reaction. The modified expressions for charge and energy flux, due to effect of
one loop back reaction are obtained.Comment: 6 pages, no figures, minor changes and references added, to appear in
Classical and Quantum Gravit
Liquidus surfaces in a part of the systems ZnO-PbO-SiO_2 and ZnO-"FeO"-SiO_2
Liquidus surfaces in a part of the systems ZnO-PbO-SiO_2 and ZnO-"FeO"-SiO_2 were constructed by quenching method. The experiments were carried out in air in the system ZnO-PbO-SiO_2. In the part investigated the primary phases were three ternary compounds (PbO・ZnO・SiO_2, 2PbO・ZnO・2SiO_2 and barysilite) , three lead silicates, Zn_2SiO_4 and SiO_2. Isotherms on the liquidus surface of each primary phase field were determined from 750 to 1300℃. In the system ZnO-"FeO"-SiO_2 the experiments were carried out in an atmosphere of purified nitrogen. In the part investigated the primary phases were Fe_2SiO_4, Zn_2SiO_4 and SiO_2. Isotherms on the liquidus surface of each primary phase field from 1150 to 1300℃ and the ternary eutectic (1130℃, 15.9% ZnO, 48.2% "FeO" and 35.9% SiO_2) were determined
The Surprisingly Steep Mass Profile of Abell 1689, from a Lensing Analysis of Subaru Images
Subaru observations of A1689 (z=0.183) are used to derive an accurate,
model-independent mass profile for the entire cluster, r<2 Mpc/h, by combining
magnification bias and distortion measurements. The projected mass profile
steepens quickly with increasing radius, falling away to zero at r~1.0 Mpc/h,
well short of the anticipated virial radius. Our profile accurately matches
onto the inner profile, r<200 kpc/h, derived from deep HST/ACS images. The
combined ACS and Subaru information is well fitted by an NFW profile with
virial mass, (1.93 \pm 0.20)10^15 M_sun, and surprisingly high concentration,
c_vir=13.7^{+1.4}_{-1.1}, significantly larger than theoretically expected
(c_vir~4), corresponding to a relatively steep overall profile. A slightly
better fit is achieved with a steep power-law model that has its 2D logarithmic
slope -3 and core radius theta_c~1.7' (r_c~210 kpc/h), whereas an isothermal
profile is strongly rejected. These results are based on a reliable sample of
background galaxies selected to be redder than the cluster E/S0 sequence. By
including the faint blue galaxy population a much smaller distortion signal is
found, demonstrating that blue cluster members significantly dilute the true
signal for r~400 kpc/h. This contamination is likely to affect most weak
lensing results to date.Comment: 5 pages, 3 figures, to appear in ApJ
A Free-Form Lensing Grid Solution for A1689 with New Mutiple Images
Hubble Space Telescope imaging of the galaxy cluster Abell 1689 has revealed
an exceptional number of strongly lensed multiply-imaged galaxies, including
high-redshift candidates. Previous studies have used this data to obtain the
most detailed dark matter reconstructions of any galaxy cluster to date,
resolving substructures ~25 kpc across. We examine Abell 1689 (hereafter,
A1689) non-parametrically, combining strongly lensed images and weak
distortions from wider field Subaru imaging, and we incorporate member galaxies
to improve the lens solution. Strongly lensed galaxies are often locally
affected by member galaxies, however, these perturbations cannot be recovered
in grid based reconstructions because the lensing information is too sparse to
resolve member galaxies. By adding luminosity-scaled member galaxy deflections
to our smooth grid we can derive meaningful solutions with sufficient accuracy
to permit the identification of our own strongly lensed images, so our model
becomes self consistent. We identify 11 new multiply lensed system candidates
and clarify previously ambiguous cases, in the deepest optical and NIR data to
date from Hubble and Subaru. Our improved spatial resolution brings up new
features not seen when the weak and strong lensing effects are used separately,
including clumps and filamentary dark matter around the main halo. Our
treatment means we can obtain an objective mass ratio between the cluster and
galaxy components, for examining the extent of tidal stripping of the luminous
member galaxies. We find a typical mass-to-light ratios of M/L_B = 21 inside
the r<1 arcminute region that drops to M/L_B = 17 inside the r<40 arcsecond
region. Our model independence means we can objectively evaluate the
competitiveness of stacking cluster lenses for defining the geometric
lensing-distance-redshift relation in a model independent way.Comment: 23 pages with 25 figures Replced with MNRAS submitted version. Some
figures have been corrected and minor text edit
- …