927 research outputs found

    Three-dimensional Black Holes and Liouville Field Theory

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    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 diffS1^±\hat{diff S^1}_{\pm}. 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 c1c \gg 1, 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 SL2(R)SL_2({\bf R}) 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

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    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

    Three-dimensional multi-probe analysis of the galaxy cluster A1689

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    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 BVRCiz{{BVR}}_{{\rm C}}i\prime z\prime 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 c200c2D=8.9±1.1{c}_{200{\rm c}}^{2{\rm D}}=8.9\pm 1.1 (cvir2D11{c}_{\mathrm{vir}}^{2{\rm D}}\sim 11), 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 M200c=(1.2±0.2)×1015  M  h1{M}_{200{\rm c}}=(1.2\pm 0.2)\times {10}^{15}\;{M}_{\odot }\;{h}^{-1} and a halo concentration c200c=8.4±1.3{c}_{200{\rm c}}=8.4\pm 1.3, which overlaps with the 1σ\gtrsim 1\sigma 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 102+3%{10}_{-2}^{+3}\%, 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

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    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

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    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

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    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

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    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
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