14,967 research outputs found
The Sloan-Lens ACS Survey II: stellar populations and internal structure of early-type lens galaxies
We derive Fundamental Plane parameters of 15 early-type lens galaxies
identified by the Sloan Lens ACS (SLACS) Survey. The size of the sample allows
us to investigate for the first time the distribution of lens galaxies in the
FP space. After correcting for evolution, we find that lens galaxies occupy a
subset of the local FP. The edge-on projection (approximately M vs M/L) is
indistinguishable from that of normal early-type galaxies. However -- within
the fundamental plane -- the lens galaxies appear to concentrate at the edge of
the region populated by normal early-type galaxies. We show that this is a
result of our selection procedure (approximately velocity dispersion
sigma>240km/s). We conclude that SLACS lenses are a fair sample of high
velocity dispersion early-type galaxies. By comparing the central stellar
velocity dispersion that of the best fit lens model, we find
== =1.01+-0.02 with 0.065 rms scatter. We conclude that
within the Einstein radii the SLACS lenses are very well approximated by
isothermal ellipsoids, requiring a fine tuning of the stellar and dark matter
distribution (bulge-halo ``conspiracy''). Interpreting the offset from the
local FP in terms of evolution of the stellar mass-to-light ratio, we find for
the SLACS lenses d log M/L_B/dz=-0.69+-0.08 (rms 0.11) consistent with the rate
found for field early-type galaxies and with a scenario where most of the stars
were formed at high redshift (>2) with secondary episodes of star formation
providing less than ~10% of the stellar mass below z=1. We discuss star
formation history and structural homogeneity in the context of formation
mechanisms such as collisionless (``dry'') mergers. [Abridged]Comment: 2006, ApJ, 604, 622; 13 pages, 7 figures, 2 tables. Replaced Table 2,
since the previous version was incorrectly sorted. Updated references. No
changes in plots or content. More info available at SLACS website
www.slacs.or
Commuting self-adjoint extensions of symmetric operators defined from the partial derivatives
We consider the problem of finding commuting self-adjoint extensions of the
partial derivatives {(1/i)(\partial/\partial x_j):j=1,...,d} with domain
C_c^\infty(\Omega) where the self-adjointness is defined relative to
L^2(\Omega), and \Omega is a given open subset of R^d. The measure on \Omega is
Lebesgue measure on R^d restricted to \Omega. The problem originates with I.E.
Segal and B. Fuglede, and is difficult in general. In this paper, we provide a
representation-theoretic answer in the special case when \Omega=I\times\Omega_2
and I is an open interval. We then apply the results to the case when \Omega is
a d-cube, I^d, and we describe possible subsets \Lambda of R^d such that
{e^(i2\pi\lambda \dot x) restricted to I^d:\lambda\in\Lambda} is an orthonormal
basis in L^2(I^d).Comment: LaTeX2e amsart class, 18 pages, 2 figures; PACS numbers 02.20.Km,
02.30.Nw, 02.30.Tb, 02.60.-x, 03.65.-w, 03.65.Bz, 03.65.Db, 61.12.Bt,
61.44.B
Optimization of diarylazines as anti-HIV agents with dramatically
Non-nucleoside inhibitors of HIV-1 reverse transcriptase are reported that have ca. 100-fold greater solubility than the structurally related drugs etravirine and rilpivirine, while retaining high anti-viral activity. The solubility enhancements come from strategic placement of a morpholinylalkoxy substituent in the entrance channel of the NNRTI binding site. Compound 4d shows low-nanomolar activity similar to etravirine towards wild-type HIV-1 and key viral variants.Fil: Bollini, Mariela. University of Yale; Estados Unidos. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Cisneros, JosĂ© A.. University of Yale; Estados UnidosFil: Spasov, Krasimir A.. University of Yale; Estados UnidosFil: Anderson, Karen S.. University of Yale; Estados UnidosFil: Jorgensen, William L.. University of Yale; Estados Unido
Redshift-Distance Survey of Early-type Galaxies. I. Sample Selection, Properties and Completeness
This is the first in a series of papers describing the recently completed
all-sky redshift-distance survey of nearby early-type galaxies (ENEAR) carried
out for peculiar velocity analysis. The sample is divided into two parts and
consists of 1607 elliptical and lenticular galaxies with cz < 7000 km/s and
with blue magnitudes brighter than m_B=14.5 (ENEARm), and of galaxies in
clusters (ENEARc). Galaxy distances based on the Dn-sigma and Fundamental Plane
(FP) relations are now available for 1359 and 1107 ENEARm galaxies,
respectively, with roughly 80% based on new data gathered by our group. The
Dn-sigma and FP template distance relations are derived by combining 569 and
431 galaxies in 28 clusters, respectively, of which about 60% are based on our
new measurements. The ENEARm redshift-distance survey extends the earlier work
of the 7S and the recent Tully-Fisher surveys sampling a comparable volume. In
subsequent papers of this series we intend to use the ENEAR sample by itself or
in combination with the SFI Tully-Fisher survey to analyze the properties of
the local peculiar velocity field and to test how sensitive the results are to
different sampling and to the distance indicators. We also anticipate that the
homogeneous database assembled will be used for a variety of other applications
and serve as a benchmark for similar studies at high-redshift.Comment: 43 pages, 15 figures, submitted to the Astronomical Journa
A More Fundamental Plane
We combine strong-lensing masses with SDSS stellar velocity dispersions and
HST-ACS effective (half-light) radii for 36 lens galaxies from the Sloan Lens
ACS (SLACS) Survey to study the mass dependence of mass-dynamical structure in
early-type galaxies. We find that over a 180--390 km/s range in velocity
dispersion, structure is independent of lensing mass to within 5%. This result
suggests a systematic variation in the total (i.e., luminous plus dark matter)
mass-to-light ratio as the origin of the tilt of the fundamental plane (FP)
scaling relationship between galaxy size, velocity dispersion, and surface
brightness. We construct the FP of the lens sample, which we find to be
consistent with the FP of the parent SDSS early-type galaxy population, and
present the first observational correlation between mass-to-light ratio and
residuals about the FP. Finally, we re-formulate the FP in terms of surface
mass density rather than surface brightness. By removing the complexities of
stellar-population effects, this mass-plane formulation will facilitate
comparison to numerical simulations and possible use as a cosmological distance
indicator.Comment: 4+epsilon pages, 1 figure, emulateapj. Revised version accepted for
publication in the ApJ Letter
Redshift-distance Survey of Early-type Galaxies: The D_n-sigma Relation
In this paper R-band photometric and velocity dispersion measurements for a
sample of 452 elliptical and S0 galaxies in 28 clusters are used to construct a
template D_n-sigma relation. This template relation is constructed by combining
the data from the 28 clusters, under the assumption that galaxies in different
clusters have similar properties. The photometric and spectroscopic data used
consist of new as well as published measurements, converted to a common system,
as presented in a accompanying paper. The resulting direct relation, corrected
for incompleteness bias, is log{D_n} =1.203 log{sigma} + 1.406; the zero-point
has been defined by requiring distant clusters to be at rest relative to the
CMB. This zero-point is consistent with the value obtained by using the
distance to Virgo as determined by the Cepheid period-luminosity relation. This
new D_n-sigma relation leads to a peculiar velocity of -72 (\pm 189) km/s for
the Coma cluster. The scatter in the distance relation corresponds to a
distance error of about 20%, comparable to the values obtained for the
Fundamental Plane relation. Correlations between the scatter and residuals of
the D_n-sigma relation with other parameters that characterize the cluster
and/or the galaxy stellar population are also analyzed. The direct and inverse
relations presented here have been used in recent studies of the peculiar
velocity field mapped by the ENEAR all-sky sample.Comment: 46 pages, 20 figures, and 7 tables. To appear in AJ, vol. 123, no. 5,
May 200
Construction of Parseval wavelets from redundant filter systems
We consider wavelets in L^2(R^d) which have generalized multiresolutions.
This means that the initial resolution subspace V_0 in L^2(R^d) is not singly
generated. As a result, the representation of the integer lattice Z^d
restricted to V_0 has a nontrivial multiplicity function. We show how the
corresponding analysis and synthesis for these wavelets can be understood in
terms of unitary-matrix-valued functions on a torus acting on a certain vector
bundle. Specifically, we show how the wavelet functions on R^d can be
constructed directly from the generalized wavelet filters.Comment: 34 pages, AMS-LaTeX ("amsproc" document class) v2 changes minor typos
in Sections 1 and 4, v3 adds a number of references on GMRA theory and
wavelet multiplicity analysis; v4 adds material on pages 2, 3, 5 and 10, and
two more reference
Genetic and phenotypic divergence in an island bird: isolation by distance, by colonization or by adaptation?
Discerning the relative roles of adaptive and nonadaptive processes in generating differences among populations and species, as well as how these processes interact, is a fundamental aim in biology. Both genetic and phenotypic divergence across populations can be the product of limited dispersal and gradual genetic drift across populations (isolation by distance), of colonization history and founder effects (isolation by colonization) or of adaptation to different environments preventing migration between populations (isolation by adaptation). Here, we attempt to differentiate between these processes using island populations of Berthelot's pipit (Anthus berthelotii), a passerine bird endemic to three Atlantic archipelagos. Using microsatellite markers and approximate Bayesian computation, we reveal that the northward colonization of this species ca. 8500years ago resulted in genetic bottlenecks in the colonized archipelagos. We then show that high levels of genetic structure exist across archipelagos and that these are consistent with a pattern of isolation by colonization, but not with isolation by distance or adaptation. Finally, we show that substantial morphological divergence also exists and that this is strongly concordant with patterns of genetic structure and bottleneck history, but not with environmental differences or geographic distance. Overall, our data suggest that founder effects are responsible for both genetic and phenotypic changes across archipelagos. Our findings provide a rare example of how founder effects can persist over evolutionary timescales and suggest that they may play an important role in the early stages of speciation
Near-Infrared Imaging of Early-Type Galaxies III. The Near-Infrared Fundamental Plane
Near-infrared imaging data on 251 early-type galaxies in clusters and groups
are used to construct the near-infrared Fundamental Plane (FP) r_eff ~
sigma_0^1.53 _eff^-0.79. The slope of the FP therefore departs from
the virial expectation of r_eff ~ sigma_0^2 _eff^-1 at all optical and
near-infrared wavelengths, which could be a result of the variation of M/L
along the elliptical galaxy sequence, or a systematic breakdown of homology
among the family of elliptical galaxies. The slope of the near-infrared FP
excludes metallicity variations as the sole cause of the slope of the FP. Age
effects, dynamical deviations from a homology, or any combination of these
(with or without metallicity), however, are not excluded. The scatter of both
the near-infrared and optical FP are nearly identical and substantially larger
than the observational uncertainties, demonstrating small but significant
intrinsic cosmological scatter for the FP at all wavelengths. The lack of a
correlation of the residuals of the near-infrared FP and the residuals from the
Mg_2-sigma relation indicates that the thickness of these relations cannot be
ascribed only to age or metallicity effects. Due to this metallicity
independence, the small scatter of the near-infrared FP excludes a model in
which age and metallicity effects ``conspire'' to keep the optical FP thin. All
of these results suggest that the possible physical origins of the FP relations
are complicated due to combined effects of variations of stellar populations
and structural parameters among elliptical galaxies.Comment: to appear in The Astronomical Journal; 35 pages, including 13
Postscript figures and 1 table; uses AAS LaTeX style file
- …