907 research outputs found
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
Hawking Radiation from Charged Black Holes via Gauge and Gravitational Anomalies
Extending gr-qc/0502074, we show that in order to avoid a breakdown of
general covariance and gauge invariance at the quantum level the total flux of
charge and energy in each outgoing partial wave of a charged quantum field in a
Reissner-Nordstrom black hole background must be equal to that of a (1+1)
dimensional blackbody at the Hawking temperature with the appropriate chemical
potential.Comment: 4 pages, typos corrected, references added, version to appear in
Phys. Rev. Let
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 SunyaevâZel'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 minorâmajor 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 minorâmajor 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 2010â2011 âThe dark universe and the cosmic evolution of baryons: from current surveys to Euclidâ and by the PRIN INAF 2012 âThe universe in the box: multiscale simulations of cosmic structure.â 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 âWorld Premier International Research Center Initiative (WPI Initiative)â and the Funds for the Development of Human Resources in Science and Technology under MEXT, Japan.Peer Reviewe
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 (PbOă»ZnOă»SiO_2, 2PbOă»ZnOă»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 1300â. 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 1300â and the ternary eutectic (1130â, 15.9% ZnO, 48.2% "FeO" and 35.9% SiO_2) were determined
Anomalies, Hawking Radiations and Regularity in Rotating Black Holes
This is an extended version of our previous letter hep-th/0602146. In this
paper we consider rotating black holes and show that the flux of Hawking
radiation can be determined by anomaly cancellation conditions and regularity
requirement at the horizon. By using a dimensional reduction technique, each
partial wave of quantum fields in a d=4 rotating black hole background can be
interpreted as a (1+1)-dimensional charged field with a charge proportional to
the azimuthal angular momentum m. From this and the analysis gr-qc/0502074,
hep-th/0602146 on Hawking radiation from charged black holes, we show that the
total flux of Hawking radiation from rotating black holes can be universally
determined in terms of the values of anomalies at the horizon by demanding
gauge invariance and general coordinate covariance at the quantum level. We
also clarify our choice of boundary conditions and show that our results are
consistent with the effective action approach where regularity at the future
horizon and vanishing of ingoing modes at r=\infty are imposed (i.e. Unruh
vacuum).Comment: 21 pages, minor corrections, added an appendix to summarize our
notations for the Kaluza-Klein reductio
Joint Strong and Weak Lensing Analysis of the Massive Cluster Field J0850+3604
We present a combined strong and weak lensing analysis of the
J085007.6+360428 (J0850) field, which was selected by its high projected
concentration of luminous red galaxies and contains the massive cluster Zwicky
1953. Using Subaru/Suprime-Cam imaging and
MMT/Hectospec spectroscopy, we first perform a weak lensing shear analysis to
constrain the mass distribution in this field, including the cluster at and a smaller foreground halo at . We then add a strong
lensing constraint from a multiply-imaged galaxy in the imaging data with a
photometric redshift of . Unlike previous cluster-scale lens
analyses, our technique accounts for the full three-dimensional mass structure
in the beam, including galaxies along the line of sight. In contrast with past
cluster analyses that use only lensed image positions as constraints, we use
the full surface brightness distribution of the images. This method predicts
that the source galaxy crosses a lensing caustic such that one image is a
highly-magnified "fold arc", which could be used to probe the source galaxy's
structure at ultra-high spatial resolution ( pc). We calculate the mass
of the primary cluster to be with a concentration of , consistent with the mass-concentration relation of
massive clusters at a similar redshift. The large mass of this cluster makes
J0850 an excellent field for leveraging lensing magnification to search for
high-redshift galaxies, competitive with and complementary to that of
well-studied clusters such as the HST Frontier Fields.Comment: Accepted for publication in The Astrophysical Journal; 14 pages, 13
figures, 3 table
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
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
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