992 research outputs found
The Globular Cluster System of M60 (NGC 4649). II. Kinematics of the Globular Cluster System
We present a kinematic analysis of the globular cluster (GC) system in the
giant elliptical galaxy (gE) M60 in the Virgo cluster. Using the photometric
and spectroscopic database of 121 GCs (83 blue GCs and 38 red GCs), we have
investigated the kinematics of the GC system. We have found that the M60 GC
system shows a significant overall rotation. The rotation amplitude of the blue
GCs is slightly smaller than or similar to that of the red GCs, and their
angles of rotation axes are similar. The velocity dispersions about the mean
velocity and about the best fit rotation curve for the red GCs are marginally
larger than those for the blue GCs. Comparison of observed stellar and GC
velocity dispersion profiles with those calculated from the stellar mass
profile shows that the mass-to-light ratio should be increased as the
galactocentric distance increases, indicating the existence of an extended dark
matter halo. The entire sample of GCs in M60 is found to have a tangentially
biased velocity ellipsoid unlike the GC systems in other gEs. Two subsamples
appear to have different velocity ellipsoids. The blue GC system has a modest
tangentially biased velocity ellipsoid, while the red GC system has a modest
radially biased or an isotropic velocity ellipsoid. From the comparison of the
kinematic properties of the M60 GC system to those of other gEs (M87, M49, NGC
1399, NGC 5128, and NGC 4636), it is found that the velocity dispersion of the
blue GC system is similar to or larger than that of the red GC system except
for M60, and the rotation of the GC system is not negligible. The entire sample
of each GC system shows an isotropic velocity ellipsoid except for M60, while
the subsamples show diverse velocity ellipsoids. We discuss the implication of
these results for the formation models of the GC system in gEs.Comment: 48 pages, 16 figures. To appear in Ap
The Globular Cluster System of M60 (NGC 4649). I. CFHT MOS Spectroscopy and Database
We present the measurement of radial velocities for globular clusters in M60,
giant elliptical galaxy in the Virgo cluster. Target globular cluster
candidates were selected using the Washington photometry based on the deep
16\arcmin \times 16\arcmin images taken at the KPNO 4m and using the
photometry derived from the HST/WFPC2 archive images. The spectra of the target
objects were obtained using the Multi-Object Spectrograph (MOS) at the
Canada-France-Hawaii Telescope (CFHT). We have measured the radial velocity for
111 objects in the field of M60: 93 globular clusters (72 blue globular
clusters with and 21 red globular clusters with
), 11 foreground stars, 6 small galaxies, and the nucleus of
M60. The measured velocities of the 93 globular clusters range from
km s to km s, with a mean value of
km s, which is in good agreement with the velocity of the nucleus of M60
( km s). Combining our results with data in the
literature, we present a master catalog of radial velocities for 121 globular
clusters in M60. The velocity dispersion of the globular clusters in the master
catalog is found to be km s for the entire sample,
km s for 83 blue globular clusters, and
km s for 38 red globular clusters.Comment: 29 pages, 8 figures. To appear in Ap
Longitudinal spectral domain optical coherence tomography changes in eyes with intraocular lymphoma
BACKGROUND:
Cases of patients with primary intraocular lymphoma (PIOL) were retrospectively analyzed to describe the longitudinal intra-retinal morphological changes in PIOL as visualized on images obtained by spectral domain optical coherence tomography (SD-OCT). RESULTS:
In a retrospective case series, Heidelberg Spectralis SD-OCT images obtained in the longitudinal evaluation of patients with biopsy-proven PIOL were analyzed and assessed. The images were graded for the presence of macular edema (ME), pigment epithelial detachment (PED), subretinal fluid (SRF), and hyperreflective signals. SD-OCT scans of five eyes from five patients were assessed. Patients showed signs of inflammation, such as ME and SRF, which were resolved with treatments in some cases. Hyperreflective signals were found in all eyes in the form of nodules or bands across the retina, with the highest frequency of appearance in the ganglion cell layer, inner plexiform layer, photoreceptor layer, and retinal pigment epithelium; such signals increased with the progression of PIOL. CONCLUSION:
SD-OCT may be employed to monitor the progression of PIOL. Hyperreflective signals on OCT may correspond with increase in disease activities, along with other findings such as ME, PED, and SRF
Real-space imaging of acoustic plasmons in large-area CVD graphene
An acoustic plasmonic mode in a graphene-dielectric-metal heterostructure has
recently been spotlighted as a superior platform for strong light-matter
interaction. It originates from the coupling of graphene plasmon with its
mirror image and exhibits the largest field confinement in the limit of a
nm-thick dielectric. Although recently detected in the far-field regime,
optical near-fields of this mode are yet to be observed and characterized.
Direct optical probing of the plasmonic fields reflected by the edges of
graphene via near-field scattering microscope reveals a relatively small
damping rate of the mid-IR acoustic plasmons in our devices, which allows for
their real-space mapping even with unprotected, chemically grown, large-area
graphene at ambient conditions. We show an acoustic mode that is twice as
confined - yet 1.4 times less damped - compared to the graphene surface plasmon
under similar conditions. We also image the resonant acoustic Bloch state in a
1D array of gold nanoribbons responsible for the high efficiency of the
far-field coupling. Our results highlight the importance of acoustic plasmons
as an exceptionally promising platform for large-area graphene-based
optoelectronic devices operating in mid-IR
On Classical Equivalence Between Noncritical and Einstein Gravity : The AdS/CFT Perspectives
We find that noncritical gravity, a special class of higher derivative
gravity, is classically equivalent to Einstein gravity at the full nonlinear
level. We obtain the viscosity-to-entropy ratio and the second order transport
coefficients of the dual fluid of noncritical gravity to all orders in the
coupling of higher derivative terms. We also compute the holographic
entanglement entropy in the dual CFT of noncritical gravity. All these results
confirm the nonlinear equivalence between noncritical gravity and Einstein
gravity at the classical level.Comment: 19 pages, no figure
The UV Upturn in Elliptical Galaxies as an Age Indicator
We show that the UV flux of old stellar systems can tell us about their ages.
Two independent populations synthesis groups that have had wildly different
views have here worked together and generated two solutions that can be easily
tested using space telescopes. Proposed tests will constrain the ages of giant
Es, that are often considered the oldest populations in the universe, and thus
cosmology.Comment: LaTeX and 11 eps figures Accepted for publication in Ap
Far-ultraviolet Observations of the North Ecliptic Pole with SPEAR
We present SPEAR/FIMS far-ultraviolet observations near the North Ecliptic
Pole. This area, at b~30 degrees and with intermediate HI column, seems to be a
fairly typical line of sight that is representative of general processes in the
diffuse ISM. We detect a surprising number of emission lines of many elements
at various ionization states representing gas phases from the warm neutral
medium (WNM) to the hot ionized medium (HIM). We also detect fluorescence bands
of H2, which may be due to the ubiquitous diffuse H2 previously observed in
absorption.Comment: 5 pages, 3 figures, Accepted for publication in ApJ Letter
Indium induced band gap tailoring in AgGa(1-x)In(x)S(2) chalcopyrite structure for visible light photocatalysis
Indium was substituted at gallium site in chalcopyrite AgGaS(2) structure by using a simple solid solution method. The spectroscopic analysis using extended x-ray absorption fine structure and x-ray photoelectron spectroscopy confirmed the indium substitution in AgGaS(2) lattice. The band gap energy of AgGa(1-x)In(x)S(2) (x=0 - 1) estimated from the onset of absorption edge was found to be reduced from 2.67 eV (x=0 ) to 1.9 eV (x=1 ) by indium substitution. The theoretical and experimental studies showed that the indium s orbitals in AgGa(1-x)In(x)S(2) tailored the band gap energy, thereby modified the photocatalytic activity of the AgGa(1-x)In(x)S(2). (c) 2008 American Institute of Physicsclose217
Small anisotropy of the lower critical field and -wave two-gap feature in single crystal LiFeAs
The in- and out-of-plane lower critical fields and magnetic penetration
depths for LiFeAs were examined. The anisotropy ratio is
smaller than the expected theoretical value, and increased slightly with
increasing temperature from 0.6 to . This small degree of anisotropy
was numerically confirmed by considering electron correlation effect. The
temperature dependence of the penetration depths followed a power
law() below 0.3, with 3.5 for both and
. Based on theoretical studies of iron-based superconductors, these
results suggest that the superconductivity of LiFeAs can be represented by an
extended -wave due to weak impurity scattering effect. And the
magnitudes of the two gaps were also evaluted by fitting the superfluid density
for both the in- and out-of-plane to the two-gap model. The estimated values
for the two gaps are consistent with the results of angle resolved
photoemission spectroscopy and specific heat experiments.Comment: 10 pages, 5 figure
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