172 research outputs found
Hubble Space Telescope NICMOS Observations of RestâFrame Optical Continuum and HÉ + [N I] Emission in FSC 10214 + 4724
High-resolution 1.10, 2.05, 2.12, and 2.15 ÎŒm imaging of the gravitationally lensed system FSC 10214+4724 are presented. These data extend Hubble Space Telescope (HST) observations of the lens system to redder wavelengths, thus providing the highest resolution images to date of the rest-frame optical and narrow-line (i.e., Hα+[N II]) regions of the background quasar. The length of the arc in the wide-band continuum images increases with increasing wavelength, and the Hα+[N II] emission has a length in between that of the 1.10 and 2.05 ÎŒm emission. The structure of the arc changes from having an eastern and western peak at 1.10 ÎŒm to having a single peak in the center at 2.05 ÎŒm. The changing structure and length of the arc can be understood in terms of a model in which the background quasar consists of a region of scattered active galactic nucleus (AGN) light that dominates at 1.10 ÎŒm (rest frame 3300 Ă
), surrounded by a more extended narrow-line region. An even more extended red stellar population would thus contribute light at 2.05 ÎŒm (rest frame 6200 Ă
). In addition, the Hα+[N II] emission has structural features similar to the 1.10 ÎŒm emission normalized by the (predominantly stellar) 2.05 ÎŒm emission, possibly confirming that the 1.10 ÎŒm emission is a superposition of the sources associated with the line emission (AGNs/massive stars) and the red stellar component that dominates the 2.05 ÎŒm emission. The counterimage of the lensed quasar is detected in the 1.10 and 2.05 ÎŒm images, and the rest frame 3300 and 6200 Ă
magnifications of the lensed quasar are calculated to be 50 ± 11 and 25 ± 6, respectively, which translates into a rest-frame optical luminosity for the quasar of ~6 Ă 10^9 L_â. These magnification values are lower than the previously measured magnification of ~100 at rest frame 2400 Ă
. If the dust in the primary lensing galaxy is not affecting the measurement of the counterimage flux at 2400 and 3300 Ă
, the magnification of the quasar appears to decrease with increasing wavelength. Flux measurements of the primary lensing galaxy fit the spectral energy distribution of an unevolving elliptical galaxy at a redshift of 0.9, consistent with previous determinations of the redshift
How Filaments are Woven into the Cosmic Web
Observations indicate galaxies are distributed in a filament-dominated
web-like structure. Numerical experiments at high and low redshift of viable
structure formation theories also show filament-dominance. We present a simple
quantitative explanation of why this is so, showing that the final-state web is
actually present in embryonic form in the overdensity pattern of the initial
fluctuations, with nonlinear dynamics just sharpening the image. The web is
largely defined by the position and primordial tidal fields of rare events in
the medium, with the strongest filaments between nearby clusters whose tidal
tensors are nearly aligned. Applications of the cosmic web theory to
observations include probing cluster-cluster bridges by weak gravitational
lensing, X-rays, and the Sunyaev-Zeldovich effect and probing high redshift
galaxy-galaxy bridges by low column density Lyman alpha absorption lines.Comment: 9 pages, gzipped uuencoded postscript file, 4 figures in separate
files. The text + figures are also available from anonymous ftp site:
ftp://ftp.cita.utoronto.ca/ftp/cita/bond/bkp_natur
Lyman alpha absorption lines from mini pancakes
[Abridged abstract:] Recent numerical simulations show that many \lyal
absorption lines of column densities \nha \la 10^{15} cm are produced
in transient, mini pancakes. Such pancakes are modeled here, approximating the
initial perturbation leading to the formation of the pancake as a single
sinusoidal wave. The density and temperature profiles of the gas in the pancake
are determined for , where is the collapse redshift. The
\lyal absorption line profiles for a line of sight through the pancake are
then calculated. The absorption lines in general have wings signifying bulk
motions in the gas. It is shown that the deviation from a single Voigt profile
is large for small H I column density lines, in which the effect of bulk
motions is large. For lines with \nha > 10^{13} cm, high temperature
tend to wash out the signatures of bulk motion. The analytical modeling of mini
pancakes associated with \lyal forest lines --- with 10^{13} \la \nha \la
10^{15} cm---gives the corresponding mass scales. It is shown here
that, for typical values of cosmological parameters, absorption lines with
\nha \sim 10^{14} cm correspond to structures with baryonic mass of
M with an overdensity of at .
The value of \nha can change by a factor in the course of evolution
of the pancake in time. It is also shown that there is an upper limit to \nha
from a pancake due to the slow recombination rate and the importance of
collisional ionization at high temperatures. Mini pancakes do not give rise to
\lyal lines with \nha \ga 10^{14.5} cm, for \j21=1 and
.Comment: Latex with aaspp4.sty (25 pages), 6 figures, Accepted for publication
in The Astrophysical Journa
NICMOS Imaging of Infrared-Luminous Galaxies
We present near-infrared images obtained with the HST NICMOS camera for a
sample of 9 luminous (LIGs: L_IR (8-1000 microns) >~ 10^11 L_sun) and 15
ultra-luminous (ULIGS: L_IR >~ 10^12 L_sun) infrared galaxies. The sample
includes representative systems classified as warm (f_25/f_60 > 0.2) and cold
(f_25/f_60 <~ 0.2) based on the mid-infrared colors and systems with nuclear
emission lines classified as HII (i.e. starburst), QSO, Seyfert and LINER. The
morphologies of the sample galaxies are diverse and provide further support for
the idea that they are created by the collision or interactions of spiral
galaxies. Although no new nuclei are seen in the NICMOS images, the NICMOS
images do reveal new spiral structures, bridges, and circumnuclear star
clusters...Comment: LaTex, 27 pages with 14 gif and 4 jpg figures, AJ, in press, contour
figures of the NICMOS images can be viewed at
http://nedwww.ipac.caltech.edu/level5/Scoville/frames.htm
Transverse Sizes of CIV Absorption Systems Measured from Multiple QSO Sightlines
We present tomography of the circum-galactic metal distribution at redshift
1.7 to 4.5 derived from echellete spectroscopy of binary quasars. We find CIV
systems at similar redshifts in paired sightlines more often than expected for
sightline-independent redshifts. As the separation of the sightlines increases
from 36 kpc to 907 kpc, the amplitude of this clustering decreases. At the
largest separations, the CIV systems cluster similar to Lyman-break galaxies
(Adelberger et al. 2005a). The CIV systems are significantly less correlated
than these galaxies, however, at separations less than R_1 ~ 0.42 +/- 0.15 h-1
comoving Mpc. Measured in real space, i.e., transverse to the sightlines, this
length scale is significantly smaller than the break scale estimated from the
line-of-sight correlation function in redshift space (Scannapieco et al.
2006a). Using a simple model, we interpret the new real-space measurement as an
indication of the typical physical size of enriched regions. We adopt this size
for enriched regions and fit the redshift-space distortion in the line-of-sight
correlation function. The fitted velocity kick is consistent with the peculiar
velocity of galaxies as determined by the underlying mass distribution and
places an upper limit on the outflow (or inflow) speed of metals. The implied
time scale for dispersing metals is larger than the typical stellar ages of
Lyman-break galaxies (Shapley et al. 2001), and we argue that enrichment by
galaxies at z > 4.3 played a greater role in dispersing metals. To further
constrain the growth of enriched regions, we discuss empirical constraints on
the evolution of the CIV correlation function with cosmic time. This study
demonstrates the potential of tomography for measuring the metal enrichment
history of the circum-galactic medium.Comment: 22 pages, 15 figures, 1 tabl
A multivalent DNA aptamer specific for the B-cell receptor on human lymphoma and leukemia
Long-term survival still eludes most patients with leukemia and non-Hodgkinâs lymphoma. No approved therapies target the hallmark of the B cell, its mIgM, also known as the B-cell receptor (BCR). Aptamers are small oligonucleotides that can specifically bind to a wide range of target molecules and offer some advantages over antibodies as therapeutic agents. Here, we report the rational engineering of aptamer TD05 into multimeric forms reactive with the BCR that may be useful in biomedical applications. Systematic truncation of TD05 coupled with modification with locked nucleic acids (LNA) increased conformational stability and nuclease resistance. Trimeric and tetrameric versions with optimized polyethyleneglycol (PEG) linker lengths exhibited high avidity at physiological temperatures both in vitro and in vivo. Competition and protease studies showed that the multimeric, optimized aptamer bound to membrane-associated human mIgM, but not with soluble IgM in plasma, allowing the possibility of targeting leukemias and lymphomas in vivo. The B-cell specificity of the multivalent aptamer was confirmed on lymphoma cell lines and fresh clinical leukemia samples. The chemically engineered aptamers, with significantly improved kinetic and biochemical features, unique specificity and desirable pharmacological properties, may be useful in biomedical applications
Pulmonary vein reconnection and repeat ablation characteristics following cryoballoonâcompared to radiofrequencyâbased pulmonary vein isolation
Background: Despite advances in efficacy and safety of pulmonary vein isolation (PVI), atrial fibrillation (AF) recurrence after PVI remains common. PVâreconnection is the main finding during repeat PVI procedures performed to treat recurrent AF. Objective: To analyze pulmonary vein (PV) reconnection patterns during repeat ablation procedures in a large cohort of consecutive patients undergoing radio frequency or cryoballoonâbased PVI. Methods: Retrospective analysis of PVâreconnection patterns and analysis of reâablation strategies in consecutive index RFâ and CBâbased PVI and their respective reâablation procedures during concomitant usage of both energy sources at a single highâvolume center in Germany. Results: A total of 610 first (06/2015â10/2022) and 133 s (01/2016â11/2022) repeat ablation procedures after 363 (60%) RFâ and 247 (40%) CBâbased index PVIs between 01/2015 and 12/2021 were analyzed. PVâreconnection was found in 509/610 (83%) patients at first and 74/133 (56%) patients at second repeat procedure. 465 of 968 (48%) initially via CB isolated PVs were reconnected at first reâablation but 796 of 1422 initially RFâisolated PV (56%) were reconnected (OR: 0.73 [95% CI: 0.62â0.86]; p < .001). This was driven by fewer reconnections of the left PVs (LSPV: OR: 0.60 [95% CI: 0.42â0.86]; p = .005 and LSPV: 0.67 [0.47â0.95]; p = .026). PVâreconnection was more likely after longer, RFâbased index PVI and in older females. Repeat procedures were shorter after CBâcompared to after RFâPVI. Conclusions: Reconnection remains the most common reason for repeat AF ablation procedures after PVI. Our data suggest to preferentially use of the cryoballoon during index PVI, especially in older women
Pulmonary vein reconnection and repeat ablation characteristics following cryoballoonâcompared to radiofrequencyâbased pulmonary vein isolation
Background: Despite advances in efficacy and safety of pulmonary vein isolation (PVI), atrial fibrillation (AF) recurrence after PVI remains common. PVâreconnection is the main finding during repeat PVI procedures performed to treat recurrent AF. Objective: To analyze pulmonary vein (PV) reconnection patterns during repeat ablation procedures in a large cohort of consecutive patients undergoing radio frequency or cryoballoonâbased PVI. Methods: Retrospective analysis of PVâreconnection patterns and analysis of reâablation strategies in consecutive index RFâ and CBâbased PVI and their respective reâablation procedures during concomitant usage of both energy sources at a single highâvolume center in Germany. Results: A total of 610 first (06/2015â10/2022) and 133 s (01/2016â11/2022) repeat ablation procedures after 363 (60%) RFâ and 247 (40%) CBâbased index PVIs between 01/2015 and 12/2021 were analyzed. PVâreconnection was found in 509/610 (83%) patients at first and 74/133 (56%) patients at second repeat procedure. 465 of 968 (48%) initially via CB isolated PVs were reconnected at first reâablation but 796 of 1422 initially RFâisolated PV (56%) were reconnected (OR: 0.73 [95% CI: 0.62â0.86]; p < .001). This was driven by fewer reconnections of the left PVs (LSPV: OR: 0.60 [95% CI: 0.42â0.86]; p = .005 and LSPV: 0.67 [0.47â0.95]; p = .026). PVâreconnection was more likely after longer, RFâbased index PVI and in older females. Repeat procedures were shorter after CBâcompared to after RFâPVI. Conclusions: Reconnection remains the most common reason for repeat AF ablation procedures after PVI. Our data suggest to preferentially use of the cryoballoon during index PVI, especially in older women
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