561 research outputs found
The Atacama Cosmology Telescope: CO(J = 3 - 2) mapping and lens modeling of an ACT-selected dusty star-forming galaxy
We report Northern Extended Millimeter Array (NOEMA) CO()
observations of the dusty star-forming galaxy ACT-S\,J020941+001557 at , which was detected as an unresolved source in the Atacama Cosmology
Telescope (ACT) equatorial survey. Our spatially resolved spectral line data
support the derivation of a gravitational lens model from 37 independent
velocity channel maps using a pixel-based algorithm, from which we infer a
velocity-dependent magnification factor with a
luminosity-weighted mean \left\approx 13. The resulting
source-plane reconstruction is consistent with a rotating disk, although other
scenarios cannot be ruled out by our data. After correction for lensing, we
derive a line luminosity , a cold gas mass , a dynamical mass , and a gas mass
fraction . The line brightness
temperature ratio of relative to a Green Bank Telescope
CO() detection may be elevated by a combination of external heating of
molecular clouds, differential lensing, and/or pointing errors.Comment: 8 pages, 5 figures, accepted to Ap
Radiation reaction and energy-momentum conservation
We discuss subtle points of the momentum balance for radiating particles in
flat and curved space-time. An instantaneous balance is obscured by the
presence of the Schott term which is a finite part of the bound field momentum.
To establish the balance one has to take into account the initial and final
conditions for acceleration, or to apply averaging. In curved space-time an
additional contribution arises from the tidal deformation of the bound field.
This force is shown to be the finite remnant from the mass renormalization and
it is different both form the radiation recoil force and the Schott force. For
radiation of non-gravitational nature from point particles in curved space-time
the reaction force can be computed substituting the retarded field directly to
the equations of motion. Similar procedure is applicable to gravitational
radiation in vacuum space-time, but fails in the non-vacuum case. The existence
of the gravitational quasilocal reaction force in this general case seems
implausible, though it still exists in the non-relativistic approximation. We
also explain the putative antidamping effect for gravitational radiation under
non-geodesic motion and derive the non-relativistic gravitational quadrupole
Schott term. Radiation reaction in curved space of dimension other than four is
also discussedComment: Lecture given at the C.N.R.S. School "Mass and Motion in General
Relativity", Orleans, France, 200
A new concurrent chemotherapy with vinorelbine and mitomycin C in combination with radiotherapy in patients with locally advanced squamous cell carcinoma of the head and neck
Objective: The purpose of this pilot study was to evaluate the feasibility and toxicity of concurrent chemotherapy with vinorelbine and mitomycin C in combination with accelerated radiotherapy (RT) in patients with locally advanced cancer of the head and neck. Patients and Methods: Between January 2003 and March 2004, 15 patients with T4/N2-3 squamous cell carcinoma (12/15) and with N3 cervical lymph node metastases of carcinoma of unknown primary (3/15) were treated with chemotherapy and simultaneous accelerated RT. Results: 11 patients completed therapy without interruption or dose reduction. Grade 3 - 4 acute mucosal toxicity was observed in 9/15 patients, grade 4 hematologic toxicity in 6/15 patients. At a median follow-up of 7.5 months, 2 patients have died of intercurrent disease, 2 patients have experienced local relapse; 5 patients are alive with no evidence of disease at the primary tumor site. Discussion: The described regimen is highly effective, but led to remarkable side effects
Mechanics of extended masses in general relativity
The "external" or "bulk" motion of extended bodies is studied in general
relativity. Compact material objects of essentially arbitrary shape, spin,
internal composition, and velocity are allowed as long as there is no direct
(non-gravitational) contact with other sources of stress-energy. Physically
reasonable linear and angular momenta are proposed for such bodies and exact
equations describing their evolution are derived. Changes in the momenta depend
on a certain "effective metric" that is closely related to a non-perturbative
generalization of the Detweiler-Whiting R-field originally introduced in the
self-force literature. If the effective metric inside a self-gravitating body
can be adequately approximated by an appropriate power series, the
instantaneous gravitational force and torque exerted on it is shown to be
identical to the force and torque exerted on an appropriate test body moving in
the effective metric. This result holds to all multipole orders. The only
instantaneous effect of a body's self-field is to finitely renormalize the
"bare" multipole moments of its stress-energy tensor. The MiSaTaQuWa expression
for the gravitational self-force is recovered as a simple application. A
gravitational self-torque is obtained as well. Lastly, it is shown that the
effective metric in which objects appear to move is approximately a solution to
the vacuum Einstein equation if the physical metric is an approximate solution
to Einstein's equation linearized about a vacuum background.Comment: 39 pages, 2 figures; fixed equation satisfied by the Green function
used to construct the effective metri
Multiwavelength characterisation of an ACT-selected, lensed dusty star-forming galaxy at z=2.64
We present \ci\,(2--1) and multi-transition CO observations of a dusty
star-forming galaxy, ACT\,J2029+0120, which we spectroscopically confirm to lie
at \,=\,2.64. We detect CO(3--2), CO(5--4), CO(7--6), CO(8--7), and
\ci\,(2--1) at high significance, tentatively detect HCO(4--3), and place
strong upper limits on the integrated strength of dense gas tracers (HCN(4--3)
and CS(7--6)). Multi-transition CO observations and dense gas tracers can
provide valuable constraints on the molecular gas content and excitation
conditions in high-redshift galaxies. We therefore use this unique data set to
construct a CO spectral line energy distribution (SLED) of the source, which is
most consistent with that of a ULIRG/Seyfert or QSO host object in the taxonomy
of the \textit{Herschel} Comprehensive ULIRG Emission Survey. We employ RADEX
models to fit the peak of the CO SLED, inferring a temperature of T117 K
and cm, most consistent with a ULIRG/QSO object
and the presence of high density tracers. We also find that the velocity width
of the \ci\ line is potentially larger than seen in all CO transitions for this
object, and that the ratio is also larger
than seen in other lensed and unlensed submillimeter galaxies and QSO hosts; if
confirmed, this anomaly could be an effect of differential lensing of a shocked
molecular outflow.Comment: Accepted for publication in Ap
A Multi-Wavelength Mass Analysis of RCS2 J232727.6-020437, a ~3x10M Galaxy Cluster at z=0.7
We present an initial study of the mass and evolutionary state of a massive
and distant cluster, RCS2 J232727.6-020437. This cluster, at z=0.6986, is the
richest cluster discovered in the RCS2 project. The mass measurements presented
in this paper are derived from all possible mass proxies: X-ray measurements,
weak-lensing shear, strong lensing, Sunyaev Zel'dovich effect decrement, the
velocity distribution of cluster member galaxies, and galaxy richness. While
each of these observables probe the mass of the cluster at a different radius,
they all indicate that RCS2 J232727.6-020437 is among the most massive clusters
at this redshift, with an estimated mass of M_200 ~3 x10^15 h^-1 Msun. In this
paper, we demonstrate that the various observables are all reasonably
consistent with each other to within their uncertainties. RCS2 J232727.6-020437
appears to be well relaxed -- with circular and concentric X-ray isophotes,
with a cool core, and no indication of significant substructure in extensive
galaxy velocity data.Comment: 19 pages, 15 figures, submitted to ApJ on March 5, 2015; in press.
Manuscript revised following the referee revie
Singular perturbation techniques in the gravitational self-force problem
Much of the progress in the gravitational self-force problem has involved the
use of singular perturbation techniques. Yet the formalism underlying these
techniques is not widely known. I remedy this situation by explicating the
foundations and geometrical structure of singular perturbation theory in
general relativity. Within that context, I sketch precise formulations of the
methods used in the self-force problem: dual expansions (including matched
asymptotic expansions), for which I identify precise matching conditions, one
of which is a weak condition arising only when multiple coordinate systems are
used; multiscale expansions, for which I provide a covariant formulation; and a
self-consistent expansion with a fixed worldline, for which I provide a precise
statement of the exact problem and its approximation. I then present a detailed
analysis of matched asymptotic expansions as they have been utilized in
calculating the self-force. Typically, the method has relied on a weak matching
condition, which I show cannot determine a unique equation of motion. I
formulate a refined condition that is sufficient to determine such an equation.
However, I conclude that the method yields significantly weaker results than do
alternative methods.Comment: 39 pages, 5 figures, final version to be published in Phys. Rev. D,
several typos corrected, added discussion of order-reductio
The Atacama Cosmology Telescope: Physical Properties of Sunyaev-Zel'dovich Effect Clusters on the Celestial Equator
We present the optical and X-ray properties of 68 galaxy clusters selected
via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope
(ACT). Our sample, from an area of 504 square degrees centered on the celestial
equator, is divided into two regions. The main region uses 270 square degrees
of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan
Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed
observations with the Apache Point Observatory 3.5-meter telescope. We confirm
a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new
discoveries. For the second region the regular-depth SDSS imaging allows us to
confirm 19 more clusters up to z~0.7, of which 10 systems are new. We present
the optical richness, photometric redshifts, and separation between the SZ
position and the brightest cluster galaxy (BCG). We find no significant offset
between the cluster SZ centroid and BCG location and a weak correlation between
optical richness and SZ-derived mass. We also present X-ray fluxes and
luminosities from the ROSAT All Sky Survey which confirm that this is a massive
sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z=1.1
(photometric), has an integrated XMM-Newton X-ray temperature of kT_x=7.9+/-1.0
keV and combined mass of M_200a=8.2(-2.5,+3.3)x10^14 M_sun/h70 placing it among
the most massive and X-ray-hot clusters known at redshifts beyond z=1. We also
highlight the optically-rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z=0.705
(spectroscopic) as the most significant detection of the whole equatorial
sample with a Chandra-derived mass of M_200a=1.9(-0.4,+0.6)x10^15 M_sun/h70,
comparable to some of the most massive known clusters like "El Gordo" and the
Bullet Cluster.Comment: 18 pages, 12 figures. Accepted to the Astrophysical Journal. New
version includes minor changes in the accepted pape
Casper Versus Precise Stent for the Treatment of Patients with Idiopathic Intracranial Hypertension.
PURPOSE
We hypothesized that due to its specific characteristics, the CasperTM RX carotid stent (CP) might be particularly suitable for venous sinus stenting (VSS) in patients with idiopathic intracranial hypertension (IIH). To test this theory, we compared it to the commonly used Precise Pro RXTM stent (PP).
METHODS
A total of 15 patients with IIH (median age 28.7 years) were reviewed retrospectively. Technical aspects as well as periinterventional and postinterventional complication rates were examined in patients treated with CP (n = 10) and the PP (n = 5). Improvements in cerebrospinal fluid opening pressure (CSF OP), transstenotic pressure gradient (TSPG) and clinical symptoms were also assessed. Results are shown as percentages and respective P-values.
RESULTS
Stent delivery was easier and more successful with the CP than the PP (difficult/failed stent delivery 0.0% versus 57.1%). No severe peri- or postinterventional complications or instances of in-stent thrombosis and/or stenosis were observed during follow-up. Improvement of CSF OP and TSPG immediately after VSS as well as at 6‑month follow-up were comparable between the CP and PP groups. Both groups showed substantial and similar decreases in intensity and frequency of headache. Almost all patients with other IIH-related symptoms showed either improvement or complete resolution of the symptoms after VSS. All patients who were available for interview (n = 12/15) reported a substantial improvement in quality of life.
CONCLUSION
A VSS using the CP seems to be safe and effective. The CP may reduce the risk of difficult or failed stent delivery in patients with challenging intracranial venous anatomy
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