28 research outputs found
Early-type galaxies in the SDSS. I. The sample
A sample of nearly 9000 early-type galaxies, in the redshift range 0.01 < z <
0.3, was selected from the Sloan Digital Sky Survey using morphological and
spectral criteria. This paper describes how the sample was selected, presents
examples of images and seeing corrected fits to the observed surface brightness
profiles, describes our method for estimating K-corrections, and shows that the
SDSS spectra are of sufficiently high quality to measure velocity dispersions
accurately. It also provides catalogs of the measured photometric and
spectroscopic parameters. In related papers, these data are used to study how
early-type galaxy observables, including luminosity, effective radius, surface
brightness, color, and velocity dispersion, are correlated with one another.Comment: 63 pages, 21 figures. Accepted by AJ (scheduled for April 2003). This
paper is part I of a revised version of astro-ph/0110344. The full version of
Tables 2 and 3, i.e. the tables listing the photometric and spectroscopic
parameters of ~ 9000 galaxies, are available at
http://astrophysics.phys.cmu.edu/~bernardi/SDSS/Etypes/TABLE
Galaxy Clustering in Early SDSS Redshift Data
We present the first measurements of clustering in the Sloan Digital Sky
Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies
with redshifts 5,700 km/s < cz < 39,000 km/s, distributed in several long but
narrow (2.5-5 degree) segments, covering 690 square degrees. For the full,
flux-limited sample, the redshift-space correlation length is approximately 8
Mpc/h. The two-dimensional correlation function \xi(r_p,\pi) shows clear
signatures of both the small-scale, ``fingers-of-God'' distortion caused by
velocity dispersions in collapsed objects and the large-scale compression
caused by coherent flows, though the latter cannot be measured with high
precision in the present sample. The inferred real-space correlation function
is well described by a power law, \xi(r)=(r/6.1+/-0.2 Mpc/h)^{-1.75+/-0.03},
for 0.1 Mpc/h < r < 16 Mpc/h. The galaxy pairwise velocity dispersion is
\sigma_{12} ~ 600+/-100 km/s for projected separations 0.15 Mpc/h < r_p < 5
Mpc/h. When we divide the sample by color, the red galaxies exhibit a stronger
and steeper real-space correlation function and a higher pairwise velocity
dispersion than do the blue galaxies. The relative behavior of subsamples
defined by high/low profile concentration or high/low surface brightness is
qualitatively similar to that of the red/blue subsamples. Our most striking
result is a clear measurement of scale-independent luminosity bias at r < 10
Mpc/h: subsamples with absolute magnitude ranges centered on M_*-1.5, M_*, and
M_*+1.5 have real-space correlation functions that are parallel power laws of
slope ~ -1.8 with correlation lengths of approximately 7.4 Mpc/h, 6.3 Mpc/h,
and 4.7 Mpc/h, respectively.Comment: 51 pages, 18 figures. Replaced to match accepted ApJ versio
Colors of 2625 Quasars at 0<z<5 Measured in the Sloan Digital Sky Survey Photometric System
We present an empirical investigation of the colors of quasars in the Sloan
Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625
quasars with SDSS photometry. The quasars are distributed in a 2.5 degree wide
stripe centered on the Celestial Equator covering square degrees.
Positions and SDSS magnitudes are given for the 898 quasars known prior to SDSS
spectroscopic commissioning. New SDSS quasars represent an increase of over
200% in the number of known quasars in this area of the sky. The ensemble
average of the observed colors of quasars in the SDSS passbands are well
represented by a power-law continuum with (). However, the contributions of the bump
and other strong emission lines have a significant effect upon the colors. The
color-redshift relation exhibits considerable structure, which may be of use in
determining photometric redshifts for quasars. The range of colors can be
accounted for by a range in the optical spectral index with a distribution
(95% confidence), but there is a red tail in the
distribution. This tail may be a sign of internal reddening. Finally, we show
that there is a continuum of properties between quasars and Seyfert galaxies
and we test the validity of the traditional division between the two classes of
AGN.Comment: 66 pages, 15 figures (3 color), accepted by A
Cosmological parameters from SDSS and WMAP
We measure cosmological parameters using the three-dimensional power spectrum
P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in
combination with WMAP and other data. Our results are consistent with a
``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt,
tensor modes or massive neutrinos. Adding SDSS information more than halves the
WMAP-only error bars on some parameters, tightening 1 sigma constraints on the
Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter
density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on
neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when
dropping prior assumptions about curvature, neutrinos, tensor modes and the
equation of state. Our results are in substantial agreement with the joint
analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive
consistency check with independent redshift survey data and analysis
techniques. In this paper, we place particular emphasis on clarifying the
physical origin of the constraints, i.e., what we do and do not know when using
different data sets and prior assumptions. For instance, dropping the
assumption that space is perfectly flat, the WMAP-only constraint on the
measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to
t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running
tilt, neutrino mass and equation of state in the list of free parameters, many
constraints are still quite weak, but future cosmological measurements from
SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt
figures available at http://www.hep.upenn.edu/~max/sdsspars.htm
Spectroscopic Target Selection for the Sloan Digital Sky Survey: The Luminous Red Galaxy Sample
We describe the target selection and resulting properties of a spectroscopic
sample of luminous, red galaxies (LRG) from the imaging data of the Sloan
Digital Sky Survey (SDSS). These galaxies are selected on the basis of color
and magnitude to yield a sample of luminous, intrinsically red galaxies that
extends fainter and further than the main flux-limited portion of the SDSS
galaxy spectroscopic sample. The sample is designed to impose a
passively-evolving luminosity and rest-frame color cut to a redshift of 0.38.
Additional, yet more luminous, red galaxies are included to a redshift of 0.5.
Approximately 12 of these galaxies per square degree are targeted for
spectroscopy, so the sample will number over 100,000 with the full survey. SDSS
commissioning data indicate that the algorithm efficiently selects luminous
(M_g=-21.4), red galaxies, that the spectroscopic success rate is very high,
and that the resulting set of galaxies is approximately volume-limited out to
z=0.38. When the SDSS is complete, the LRG spectroscopic sample will fill over
1h^-3 Gpc^3 with an approximately homogeneous population of galaxies and will
therefore be well suited to studies of large-scale structure and clusters out
to z=0.5.Comment: 30 pages, LaTeX. Accepted to the Astronomical Journa
Early-type galaxies in the SDSS. III. The Fundamental Plane
A magnitude limited sample of nearly 9000 early-type galaxies, in the
redshift range 0.01 < z < 0.3, was selected from the Sloan Digital Sky Survey
using morphological and spectral criteria. The Fundamental Plane relation in
this sample is R_o ~ sigma^{1.49\pm 0.05} I_o^{-0.75\pm 0.01} in the r* band.
It is approximately the same in the g*, i* and z* bands. Relative to the
population at the median redshift in the sample, galaxies at lower and higher
redshifts have evolved only little. If the Fundamental Plane is used to
quantify this evolution then the apparent magnitude limit can masquerade as
evolution; once this selection effect has been accounted for, the evolution is
consistent with that of a passively evolving population which formed the bulk
of its stars about 9 Gyrs ago. One of the principal advangtages of the SDSS
sample over previous samples is that the galaxies in it lie in environments
ranging from isolation in the field to the dense cores of clusters. The
Fundamental Plane shows that galaxies in dense regions are slightly different
from galaxies in less dense regions.Comment: 27 pages, 10 figures. Accepted by AJ (scheduled for April 2003). This
paper is part III of a revised version of astro-ph/011034
Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies
We present the large-scale correlation function measured from a spectroscopic
sample of 46,748 luminous red galaxies from the Sloan Digital Sky Survey. The
survey region covers 0.72 h^{-3} Gpc^3 over 3816 square degrees and
0.16<z<0.47, making it the best sample yet for the study of large-scale
structure. We find a well-detected peak in the correlation function at
100h^{-1} Mpc separation that is an excellent match to the predicted shape and
location of the imprint of the recombination-epoch acoustic oscillations on the
low-redshift clustering of matter. This detection demonstrates the linear
growth of structure by gravitational instability between z=1000 and the present
and confirms a firm prediction of the standard cosmological theory. The
acoustic peak provides a standard ruler by which we can measure the ratio of
the distances to z=0.35 and z=1089 to 4% fractional accuracy and the absolute
distance to z=0.35 to 5% accuracy. From the overall shape of the correlation
function, we measure the matter density Omega_mh^2 to 8% and find agreement
with the value from cosmic microwave background (CMB) anisotropies. Independent
of the constraints provided by the CMB acoustic scale, we find Omega_m = 0.273
+- 0.025 + 0.123 (1+w_0) + 0.137 Omega_K. Including the CMB acoustic scale, we
find that the spatial curvature is Omega_K=-0.010+-0.009 if the dark energy is
a cosmological constant. More generally, our results provide a measurement of
cosmological distance, and hence an argument for dark energy, based on a
geometric method with the same simple physics as the microwave background
anisotropies. The standard cosmological model convincingly passes these new and
robust tests of its fundamental properties.Comment: Submitted to the ApJ. Additional pedagogical material and numerical
data at http://cmb.as.arizona.edu/~eisenste/acousticpea
The Sloan Digital Sky Survey: Technical Summary
The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed
investigations of the distribution of luminous and non- luminous matter in the
Universe: a photometrically and astrometrically calibrated digital imaging
survey of pi steradians above about Galactic latitude 30 degrees in five broad
optical bands to a depth of g' about 23 magnitudes, and a spectroscopic survey
of the approximately one million brightest galaxies and 10^5 brightest quasars
found in the photometric object catalog produced by the imaging survey. This
paper summarizes the observational parameters and data products of the SDSS,
and serves as an introduction to extensive technical on-line documentation.Comment: 9 pages, 7 figures, AAS Latex. To appear in AJ, Sept 200
Prelude to a panzootic: Gene flow and immunogenetic variation in northern little brown myotis vulnerable to bat white-nose syndrome
The fungus that causes bat white-nose syndrome (WNS) recently leaped from eastern North America to the Pacific Coast. The pathogenâs spread is associated with the genetic population structure of a host (Myotis lucifugus). To understand the fine-scale neutral and immunogenetic variation among northern populations of M. lucifugus, we sampled 1142 individuals across the speciesâ northern range. We used genotypes at 11 microsatellite loci to reveal the genetic structure of, and directional gene flow among, populations to predict the likely future spread of the pathogen in the northwest and to estimate effective population size (Ne). We also pyrosequenced the DRB1-like exon 2 of the class II major histocompatibility complex (MHC) in 160 individuals to explore immunogenetic selection by WNS. We identified three major neutral genetic clusters: Eastern, Montane Cordillera (and adjacent sampling areas), and Haida Gwaii, with admixture at intermediate areas and significant substructure west of the prairies. Estimates of Ne were unexpectedly low (289â16 000). Haida Gwaii may provide temporary refuge from WNS, but the western mountain ranges are not barriers to its dispersal in M. lucifugus and are unlikely to slow its spread. Our major histocompatibility complex (MHC) data suggest potential selection by WNS on the MHC, but gene duplication limited the immunogenetic analyses
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Environmental drivers of body size in North American bats
Bergmann's ruleâwhich posits that larger animals live in colder areasâis thought to influence variation in body size within species across space and time, but evidence for this claim is mixed. We used Bayesian hierarchical models to test four competing hypotheses for spatiotemporal variation in body size within 20 bat species across North America: (1) the heat conservation hypothesis, which posits that increased body size facilitates body heat conservation (and which is the traditional explanation for the mechanism underlying Bergmann's rule); (2) the heat mortality hypothesis, which posits that increased body size increases susceptibility to acute heat stress; (3) the resource availability hypothesis, which posits that increased body size is enabled in areas with more abundant food; and (4) the starvation resistance hypothesis, which posits that increased body size reduces susceptibility to starvation during acute food shortages. Spatial variation in body mass was most consistently (and negatively) correlated with mean annual temperature, supporting the heat conservation hypothesis. Across time, variation in body mass was most consistently (and positively) correlated with net primary productivity, supporting the resource availability hypothesis. Climate change could influence body size in animals through both changes in mean annual temperature and resource availability. Rapid reductions in body size associated with increasing temperatures have occurred in short-lived, fecund species, but such reductions will be obscured by changes in resource availability in longer-lived, less fecund species. Read the free Plain Language Summary for this article on the Journal blog.Alberta Conservation Association12 month embargo; first published 31 January 2023This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]