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[show abstract]
[hide abstract]
ABSTRACT: We investigate machine learning (ML) techniques for predicting the number of
galaxies (N_gal) that occupy a halo, given the halo's properties. These types
of mappings are crucial for constructing the mock galaxy catalogs necessary for
analyses of large-scale structure. The ML techniques proposed here distinguish
themselves from traditional halo occupation distribution (HOD) modeling as they
do not assume a prescribed relationship between halo properties and N_gal. In
addition, our ML approaches are only dependent on parent halo properties (like
HOD methods), which are advantageous over subhalo-based approaches as
identifying subhalos correctly is difficult. We test 2 algorithms: support
vector machines (SVM) and k-nearest-neighbour (kNN) regression. We take
galaxies and halos from the Millennium simulation and predict N_gal by training
our algorithms on the following 6 halo properties: number of particles, M_200,
\sigma_v, v_max, half-mass radius and spin. For Millennium, our predicted N_gal
values have a mean-squared-error (MSE) of ~0.16 for both SVM and kNN. Our
predictions match the overall distribution of halos reasonably well and the
galaxy correlation function at large scales to ~5-10%. In addition, we
demonstrate a feature selection algorithm to isolate the halo parameters that
are most predictive, a useful technique for understanding the mapping between
halo properties and N_gal. Lastly, we investigate these ML-based approaches in
making mock catalogs for different galaxy subpopulations (e.g. blue, red, high
M_star, low M_star). Given its non-parametric nature as well as its powerful
predictive and feature selection capabilities, machine learning offers an
interesting alternative for creating mock catalogs.
03/2013;
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Anže Slosar,
Vid Iršič,
David Kirkby,
Stephen Bailey,
Nicolás G. Busca,
Timothée Delubac,
James Rich,
Vaishali Bhardwaj,
Michael Blomqvist,
Adam S. Bolton, [......],
Yodovina Piškur N. A. Roe,
Nicholas P. Ross,
Graziano Rossi,
David J. Schlegel,
Donald P. Schneider,
Erin S. Sheldon,
Uroš Seljak,
Matteo Viel,
David H. Weinberg,
Christophe Yèche
[show abstract]
[hide abstract]
ABSTRACT: We use the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9
(DR9) to detect and measure the position of the Baryonic Acoustic Oscillation
(BAO) feature in the three-dimensional correlation function in the Lyman-alpha
forest flux fluctuations at a redshift z=2.4. The feature is clearly detected
at significance between 3 and 5 sigma (depending on the broadband model and
method of error covariance matrix estimation) and is consistent with
predictions of the standard LCDM model. We assess the biases in our method,
stability of the error covariance matrix and possible systematic effects. We
fit the resulting correlation function with several models that decouple the
broadband and acoustic scale information. For an isotropic dilation factor, we
measure 100x(alpha_iso-1) = -1.6 ^{+2.0+4.3+7.4}_{-2.0-4.1-6.8} (stat.) +/- 1.0
(syst.) (multiple statistical errors denote 1,2 and 3 sigma confidence limits)
with respect to the acoustic scale in the fiducial cosmological model (flat
LCDM with Omega_m=0.27, h=0.7). When fitting separately for the radial and
transversal dilation factors we find marginalised constraints 100x(alpha_par-1)
= -1.3 ^{+3.5+7.6 +12.3}_{-3.3-6.7-10.2} (stat.) +/- 2.0 (syst.) and
100x(alpha_perp-1) = -2.2 ^{+7.4+17}_{-7.1-15} +/- 3.0 (syst.). The dilation
factor measurements are significantly correlated with cross-correlation
coefficient of ~ -0.55. Errors become significantly non-Gaussian for deviations
over 3 standard deviations from best fit value. Because of the data cuts and
analysis method, these measurements give tighter constraints than a previous
BAO analysis of the BOSS DR9 Lyman-alpha forest sample, providing an important
consistency test of the standard cosmological model in a new redshift regime.
01/2013;
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Hong Guo,
Idit Zehavi,
Zheng Zheng,
David H. Weinberg,
Andreas A. Berlind,
Michael Blanton,
Yanmei Chen,
Daniel J. Eisenstein, Shirley Ho,
Eyal Kazin, [......],
Luiz N. A. da Costa,
Garrett Ebelke,
Viktor Malanushenko,
Elena Malanushenko,
Daniel Oravetz,
Graziano Rossi,
Audrey Simmons,
Stephanie Snedden,
Alina Streblyanska,
Daniel Thomas
[show abstract]
[hide abstract]
ABSTRACT: We measure the luminosity and color dependence and the redshift evolution of
galaxy clustering in the Sloan Digital Sky Survey-III Baryon Oscillation
Spectroscopic Survey Ninth Data Release. We focus on the projected two-point
correlation function (2PCF) of subsets of its CMASS sample, which includes
about 260,000 galaxies over ~3,300 sq. deg in the redshift range 0.43<z<0.7. To
minimize the selection effect on galaxy clustering, we construct well-defined
luminosity and color subsamples by carefully accounting for the CMASS galaxy
selection cuts. The 2PCF of the whole CMASS sample, if approximated by a
power-law, has a correlation length of r_0=7.93\pm0.06Mpc/h and an index of
\gamma=1.85\pm0.01. Clear dependences on galaxy luminosity and color are found
for the projected 2PCF in all redshift bins, with more luminous and redder
galaxies generally exhibiting stronger clustering and steeper 2PCF. The color
dependence is also clearly seen for galaxies within the red sequence,
consistent with the behavior of SDSS-II main sample galaxies at lower
redshifts. At a given luminosity (k+e corrected), no significant evolution of
the projected 2PCFs with redshift is detected for red sequence galaxies. We
also construct galaxy samples of fixed number density at different redshifts,
using redshift-dependent magnitude thresholds. The clustering of these galaxies
in the CMASS redshift range is found to be consistent with that predicted by
passive evolution. Our measurements of the luminosity and color dependence and
redshift evolution of galaxy clustering will allow for detailed modeling of the
relation between galaxies and dark matter halos and new constraints on galaxy
formation and evolution.
12/2012;
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Khee-Gan Lee,
Stephen Bailey,
Leslie E. Bartsch,
William Carithers,
Kyle S. Dawson,
David Kirkby,
Britt Lundgren,
Daniel Margala,
Nathalie Palanque-Delabrouille,
Matthew M. Pieri, [......],
Nicholas P. Ross,
Graziano Rossi,
Donald P. Schneider,
Audrey Simmons,
Stephanie Snedden,
Anze Slosar,
David N. Spergel,
Nao Suzuki,
Matteo Viel,
Benjamin A. Weaver
[show abstract]
[hide abstract]
ABSTRACT: We present the BOSS Lyman-alpha (Lya) Forest Sample from SDSS Data Release 9,
comprising 54,468 quasar spectra with zqso > 2.15 suitable for Lya forest
analysis. This data set probes the intergalactic medium with absorption
redshifts 2.0 < z_alpha < 5.7 over an area of 3275 square degrees, and
encompasses an approximate comoving volume of 20 h^-3 Gpc^3. With each
spectrum, we have included several products designed to aid in Lya forest
analysis: improved sky masks that flag pixels where data may be unreliable,
corrections for known biases in the pipeline estimated noise, masks for the
cores of damped Lya systems and corrections for their wings, and estimates of
the unabsorbed continua so that the observed flux can be converted to a
fractional transmission. The continua are derived using a principal component
fit to the quasar spectrum redwards of restframe Lya (lambda > 1216 Ang),
extrapolated into the forest region and normalized by a linear function to fit
the expected evolution of the Lya forest mean-flux. The estimated continuum
errors are ~5% rms. We also discuss possible systematics arising from uncertain
spectrophotometry and artifacts in the flux calibration; global corrections for
the latter are provided. Our sample provides a convenient starting point for
users to analyze clustering in BOSS Lya forest data, and it provides a fiducial
data set that can be used to compare results from different analyses of baryon
acoustic oscillations in the Lya forest. The full data set is available from
the SDSS-III DR9 web site.
11/2012;
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Nicolás G. Busca,
Timothée Delubac,
James Rich,
Stephen Bailey,
Andreu Font-Ribera,
David Kirkby,
J. -M. Le Goff,
Matthew M. Pieri,
Anze Slosar,
Éric Aubourg, [......],
Erin S. Sheldon,
Audrey Simmons,
Stephanie Snedden,
Jeremy L. Tinker,
Matteo Viel,
Benjamin A. Weaver,
David H. Weinberg,
Martin White,
Christophe Yèche,
Donald G. York
[show abstract]
[hide abstract]
ABSTRACT: We report a detection of the baryon acoustic oscillation (BAO) feature in the
three-dimensional correlation function of the transmitted flux fraction in the
\Lya forest of high-redshift quasars. The study uses 48,640 quasars in the
redshift range $2.1\le z \le 3.5$ from the Baryon Oscillation Spectroscopic
Survey (BOSS) of the third generation of the Sloan Digital Sky Survey
(SDSS-III). At a mean redshift $z=2.3$, we measure the monopole and quadrupole
components of the correlation function for separations in the range
$20\hMpc<r<200\hMpc$. A peak in the correlation function is seen at a
separation equal to $(1.01\pm0.03)$ times the distance expected for the BAO
peak within a concordance $\Lambda$CDM cosmology. This first detection of the
BAO peak at high redshift, when the universe was strongly matter dominated,
results in constraints on the angular diameter distance $\da$ and the expansion
rate $H$ at $z=2.3$ that, combined with priors on $H_0$ and the baryon density,
require the existence of dark energy. Combined with constraints derived from
Cosmic Microwave Background (CMB) observations, this result implies
$H(z=2.3)=(224\pm8){\rm km\,s^{-1}Mpc^{-1}}$, indicating that the time
derivative of the cosmological scale parameter $\dot{a}=H(z=2.3)/(1+z)$ is
significantly greater than that measured with BAO at $z\sim0.5$. This
demonstrates that the expansion was decelerating in the range $0.7<z<2.3$, as
expected from the matter domination during this epoch. Combined with
measurements of $H_0$, one sees the pattern of deceleration followed by
acceleration characteristic of a dark-energy dominated universe.
11/2012;
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Kyle S. Dawson,
David J. Schlegel,
Christopher P. Ahn,
Scott F. Anderson,
Éric Aubourg,
Stephen Bailey,
Robert H. Barkhouser,
Julian E. Bautista,
Alessandra Beifiori,
Andreas A. Berlind, [......],
Benjamin A. Weaver,
David H. Weinberg,
Benjamin J. Weiner,
Andrew A. West,
Martin White,
W. M. Wood-Vasey,
Christophe Yeche,
Idit Zehavi,
Gong-Bo Zhao,
Zheng Zheng
[show abstract]
[hide abstract]
ABSTRACT: The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the
scale of baryon acoustic oscillations (BAO) in the clustering of matter over a
larger volume than the combined efforts of all previous spectroscopic surveys
of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as
i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7.
Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000
quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5.
Early results from BOSS include the first detection of the large-scale
three-dimensional clustering of the Lyman alpha forest and a strong detection
from the Data Release 9 data set of the BAO in the clustering of massive
galaxies at an effective redshift z = 0.57. We project that BOSS will yield
measurements of the angular diameter distance D_A to an accuracy of 1.0% at
redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the
same redshifts. Forecasts for Lyman alpha forest constraints predict a
measurement of an overall dilation factor that scales the highly degenerate
D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey
is complete. Here, we provide an overview of the selection of spectroscopic
targets, planning of observations, and analysis of data and data quality of
BOSS.
07/2012;
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SDSS-III Collaboration: Christopher P. Ahn,
Rachael Alexandroff,
Carlos Allende Prieto,
Scott F. Anderson,
Timothy Anderton,
Brett H. Andrews,
Éric Aubourg Stephen Bailey,
Rory Barnes,
Julian Bautista,
Timothy C. Beers, [......],
Brian Yanny,
Christophe Yèche,
Donald G. York,
O. Zamora,
Gail Zasowski,
Idit Zehavi,
Gong-Bo Zhao,
Zheng Zheng,
Guangtun Zhu,
Joel C. Zinn
[show abstract]
[hide abstract]
ABSTRACT: The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic
data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data
release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median
z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar
spectra, along with the data presented in previous data releases. These spectra
were obtained with the new BOSS spectrograph and were taken between 2009
December and 2011 July. In addition, the stellar parameters pipeline, which
determines radial velocities, surface temperatures, surface gravities, and
metallicities of stars, has been updated and refined with improvements in
temperature estimates for stars with T_eff<5000 K and in metallicity estimates
for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars
presented in DR8, including stars from SDSS-I and II, as well as those observed
as part of the SDSS-III Sloan Extension for Galactic Understanding and
Exploration-2 (SEGUE-2).
The astrometry error introduced in the DR8 imaging catalogs has been
corrected in the DR9 data products. The next data release for SDSS-III will be
in Summer 2013, which will present the first data from the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) along with another year of
data from BOSS, followed by the final SDSS-III data release in December 2014.
07/2012;
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Ashley J. Ross,
Will J. Percival,
Ariel G. Sanchez,
Lado Samushia, Shirley Ho,
Eyal Kazin,
Marc Manera,
Beth Reid,
Martin White,
Rita Tojeiro, [......],
Antonio J. Cuesta,
Elena Malanushenko,
Viktor Malanushenko,
Daniel Oravetz,
John Parejko,
Kaike Pan,
Donald P. Schneider Alaina Shelden,
Audrey Simmons,
Stephanie Snedden,
Gong-bo Zhao
[show abstract]
[hide abstract]
ABSTRACT: We analyze the density field of galaxies observed by the Sloan Digital Sky
Survey (SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS) included in
the SDSS Data Release Nine (DR9). DR9 includes spectroscopic redshifts for over
400,000 galaxies spread over a footprint of 3,275 deg^2. We identify,
characterize, and mitigate the impact of sources of systematic uncertainty on
large-scale clustering measurements, both for angular moments of the
redshift-space correlation function and the spherically averaged power
spectrum, P(k), in order to ensure that robust cosmological constraints will be
obtained from these data. A correlation between the projected density of stars
and the higher redshift (0.43 < z < 0.7) galaxy sample (the `CMASS' sample) due
to imaging systematics imparts a systematic error that is larger than the
statistical error of the clustering measurements at scales s > 120h^-1Mpc or k
< 0.01hMpc^-1. We find that these errors can be ameliorated by weighting
galaxies based on their surface brightness and the local stellar density. We
use mock galaxy catalogs that simulate the CMASS selection function to
determine that randomly selecting galaxy redshifts in order to simulate the
radial selection function of a random sample imparts the least systematic error
on correlation function measurements and that this systematic error is
negligible for the spherically averaged correlation function. The methods we
recommend for the calculation of clustering measurements using the CMASS sample
are adopted in companion papers that locate the position of the baryon acoustic
oscillation feature (Anderson et al. 2012), constrain cosmological models using
the full shape of the correlation function (Sanchez et al. 2012), and measure
the rate of structure growth (Reid et al. 2012). (abridged)
Monthly Notices of the Royal Astronomical Society 07/2012; 424(1). · 4.90 Impact Factor
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Lauren Anderson,
Eric Aubourg,
Stephen Bailey,
Dmitry Bizyaev,
Michael Blanton,
Adam S. Bolton,
J. Brinkmann,
Joel R. Brownstein,
Angela Burden,
Antonio J. Cuesta, [......],
Licia Verde,
Christian Wagner,
David A. Wake,
Benjamin A. Weaver,
David H. Weinberg,
Martin White,
Xiaoying Xu,
Christophe Yeche,
Idit Zehavi,
Gong-Bo Zhao
[show abstract]
[hide abstract]
ABSTRACT: We present measurements of galaxy clustering from the Baryon Oscillation
Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III
(SDSS-III). These use the Data Release 9 (DR9) CMASS sample, which contains
264,283 massive galaxies covering 3275 square degrees with an effective
redshift z=0.57 and redshift range 0.43 < z < 0.7. Assuming a concordance
Lambda-CDM cosmological model, this sample covers an effective volume of 2.2
Gpc^3, and represents the largest sample of the Universe ever surveyed at this
density, n = 3 x 10^-4 h^-3 Mpc^3. We measure the angle-averaged galaxy
correlation function and power spectrum, including density-field reconstruction
of the baryon acoustic oscillation (BAO) feature. The acoustic features are
detected at a significance of 5\sigma in both the correlation function and
power spectrum. Combining with the SDSS-II Luminous Red Galaxy Sample, the
detection significance increases to 6.7\sigma. Fitting for the position of the
acoustic features measures the distance to z=0.57 relative to the sound horizon
DV /rs = 13.67 +/- 0.22 at z=0.57. Assuming a fiducial sound horizon of 153.19
Mpc, which matches cosmic microwave background constraints, this corresponds to
a distance DV(z=0.57) = 2094 +/- 34 Mpc. At 1.7 per cent, this is the most
precise distance constraint ever obtained from a galaxy survey. We place this
result alongside previous BAO measurements in a cosmological distance ladder
and find excellent agreement with the current supernova measurements. We use
these distance measurements to constrain various cosmological models, finding
continuing support for a flat Universe with a cosmological constant.
03/2012;
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Shirley Ho,
Antonio Cuesta,
Hee-Jong Seo,
Roland de Putter,
Ashley J. Ross,
Martin White,
Nikhil Padmanabhan,
Shun Saito,
David J. Schlegel,
Eddie Schlafly, [......],
Viktor Malanushenko,
Bob Nichol,
Daniel Oravetz,
Kaike Pan,
Nathalie Palanque-Delabrouille,
Nicholas P Ross,
Audrey Simmons,
Fernando de Simoni,
Stephanie Snedden,
Christophe Yeche
[show abstract]
[hide abstract]
ABSTRACT: The Sloan Digital Sky Survey (SDSS) surveyed 14,555 square degrees, and
delivered over a trillion pixels of imaging data. We present a study of galaxy
clustering using 900,000 luminous galaxies with photometric redshifts, spanning
between $z=0.45$ and $z=0.65$, constructed from the SDSS using methods
described in Ross et al. (2011). This data-set spans 11,000 square degrees and
probes a volume of $3h^{-3} \rm{Gpc}^3$, making it the largest volume ever used
for galaxy clustering measurements. We present a novel treatment of the
observational systematics and its applications to the clustering signals from
the data set. In this paper, we measure the angular clustering using an optimal
quadratic estimator at 4 redshift slices with an accuracy of ~15% with bin size
of delta_l = 10 on scales of the Baryon Acoustic Oscillations (BAO) (at
l~40-400). We derive cosmological constraints using the full-shape of the
power-spectra. For a flat Lambda CDM model, when combined with Cosmic Microwave
Background Wilkinson Microwave Anisotropy Probe 7 (WMAP7) and H_0 constraints
from 600 Cepheids observed by HST, we find \Omega_\Lambda = 0.73 +/- 0.019 and
H_0 to be 70.5 +/- 1.6 km/s/Mpc. For an open Lambda CDM model, when combined
with WMAP7 + HST, we find $\Omega_K = 0.0035 +/- 0.0054, improved over
WMAP7+HST alone by 40%. For a wCDM model, when combined with WMAP7+HST+SN, we
find w = -1.071 +/- 0.078, and H_0 to be 71.3 +/- 1.7 km/s/Mpc, which is
competitive with the latest large scale structure constraints from large
spectroscopic surveys such as SDSS Data Release 7 (DR7) (Reid et al. 2010,
Percival et al. 2010, Montesano et al. 2011) and WiggleZ (Blake et al. 2011).
The SDSS-III Data Release 8 (SDSS-III DR8) Angular Clustering Data allows a
wide range of investigations into the cosmological model, cosmic expansion (via
BAO), Gaussianity of initial conditions and neutrino masses. (abridged)
01/2012;
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Hee-Jong Seo, Shirley Ho,
Martin White,
Antonio Cuesta,
Ashley Ross,
Shun Saito,
Beth Reid,
Nikhil Padmanabhan,
Will J. Percival,
Roland de Putter, [......],
Dan Oravetz,
Nathalie Palanque-Delabrouille,
Kaike Pan,
Francisco Prada,
Nicholas Ross,
Audrey Simmons,
Fernando Simoni,
Alaina Shelden,
Stephanie Snedden,
Idit Zehavi
[show abstract]
[hide abstract]
ABSTRACT: We measure the acoustic scale from the angular power spectra of the Sloan
Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalog that includes
872,921 galaxies over ~ 10,000 deg^2 between 0.45<z<0.65. The extensive
spectroscopic training set of the Baryon Oscillation Spectroscopic Survey
(BOSS) luminous galaxies allows precise estimates of the true redshift
distributions of galaxies in our imaging catalog. Utilizing the redshift
distribution information, we build templates and fit to the power spectra of
the data, which are measured in our companion paper, Ho et al. 2011, to derive
the location of Baryon acoustic oscillations (BAO) while marginalizing over
many free parameters to exclude nearly all of the non-BAO signal. We derive the
ratio of the angular diameter distance to the sound horizon scale D_A/r_s=
9.212 + 0.416 -0.404 at z=0.54, and therefore, D_A= 1411+- 65 Mpc at z=0.54;
the result is fairly independent of assumptions on the underlying cosmology.
Our measurement of angular diameter distance D_A is 1.4 \sigma higher than what
is expected for the concordance LCDM (Komatsu et al. 2011), in accordance to
the trend of other spectroscopic BAO measurements for z >~ 0.35. We report
constraints on cosmological parameters from our measurement in combination with
the WMAP7 data and the previous spectroscopic BAO measurements of SDSS
(Percival et al. 2010) and WiggleZ (Blake et al. 2011). We refer to our
companion papers (Ho et al. 2011; de Putter et al. 2011) for investigations on
information of the full power spectrum.
01/2012;
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Roland de Putter,
Olga Mena,
Elena Giusarma, Shirley Ho,
Antonio Cuesta,
Hee-Jong Seo,
Ashley Ross,
Martin White,
Dmitry Bizyaev,
Howard Brewington, [......],
Elena Malanushenko,
Viktor Malanushenko,
Daniel Oravetz,
Kaike Pan,
Will J. Percival,
Nicholas P. Ross,
Donald P. Schneider,
Alaina Shelden,
Audrey Simmons,
Stephanie Snedden
[show abstract]
[hide abstract]
ABSTRACT: We present neutrino mass bounds using 900,000 luminous galaxies with
photometric redshifts measured from Sloan Digital Sky Survey III Data Release
Eight (SDSS DR8). The galaxies have photometric redshifts between $z = 0.45$
and $z = 0.65$, and cover 10,000 square degrees and thus probe a volume of
3$h^{-3}$Gpc$^3$, enabling tight constraints to be derived on the amount of
dark matter in the form of massive neutrinos. A new bound on the sum of
neutrino masses $\sum m_\nu < 0.26$ eV, at 95% confidence level (CL), is
obtained after combining our sample of galaxies, which we call "CMASS", with
WMAP 7 year Cosmic Microwave Background (CMB) data and the most recent
measurement of the Hubble parameter from the Hubble Space Telescope (HST). This
constraint is obtained with a conservative multipole range choice of $30 < \ell
< 200$ in order to minimize non-linearities, and a free bias parameter in each
of the four redshift bins. We study the impact of assuming this linear galaxy
bias model using mock catalogs, and find that this model causes a small ($\sim
1-1.5 \sigma$) bias in $\Omega_{\rm DM} h^2$. For this reason, we also quote
neutrino bounds based on a conservative galaxy bias model containing
additional, shot noise-like free parameters. In this conservative case, the
bounds are significantly weakened, e.g. $\sum m_\nu < 0.36$ eV (95% confidence
level) for WMAP+HST+CMASS ($\ell_{\rm max}=200$). We also study the dependence
of the neutrino bound on multipole range ($\ell_{\rm max}=150$ vs $\ell_{\rm
max}=200$) and on which combination of data sets is included as a prior. The
addition of supernova and/or Baryon Acoustic Oscillation data does not
significantly improve the neutrino mass bound once the HST prior is included.
[abridged]
01/2012;
-
Daniel J. Eisenstein,
David H. Weinberg,
Eric Agol,
Hiroaki Aihara,
Carlos Allende Prieto,
Scott F. Anderson,
James A. Arns,
Éric Aubourg,
Stephen Bailey,
Eduardo Balbinot, [......],
John P. Wisniewski,
W. Michael Wood-Vasey,
Brian Yanny,
Naoki Yasuda,
Christophe Yèche,
Donald G. York,
Erick Young,
Gail Zasowski,
Idit Zehavi,
and Bo Zhao
[show abstract]
[hide abstract]
ABSTRACT: Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS Data Release 8 (DR8), which was made public in 2011 January and includes SDSS-I and SDSS-II images and spectra reprocessed with the latest pipelines and calibrations produced for the SDSS-III investigations. This paper presents an overview of the four surveys that comprise SDSS-III. The Baryon Oscillation Spectroscopic Survey will measure redshifts of 1.5 million massive galaxies and Lyα forest spectra of 150,000 quasars, using the baryon acoustic oscillation feature of large-scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z < 0.7 and at z 2.5. SEGUE-2, an already completed SDSS-III survey that is the continuation of the SDSS-II Sloan Extension for Galactic Understanding and Exploration (SEGUE), measured medium-resolution (R = λ/Δλ 1800) optical spectra of 118,000 stars in a variety of target categories, probing chemical evolution, stellar kinematics and substructure, and the mass profile of the dark matter halo from the solar neighborhood to distances of 100 kpc. APOGEE, the Apache Point Observatory Galactic Evolution Experiment, will obtain high-resolution (R 30,000), high signal-to-noise ratio (S/N ≥ 100 per resolution element), H-band (1.51 μm < λ < 1.70 μm) spectra of 105 evolved, late-type stars, measuring separate abundances for ~15 elements per star and creating the first high-precision spectroscopic survey of all Galactic stellar populations (bulge, bar, disks, halo) with a uniform set of stellar tracers and spectral diagnostics. The Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) will monitor radial velocities of more than 8000 FGK stars with the sensitivity and cadence (10-40 m s–1, ~24 visits per star) needed to detect giant planets with periods up to two years, providing an unprecedented data set for understanding the formation and dynamical evolution of giant planet systems. As of 2011 January, SDSS-III has obtained spectra of more than 240,000 galaxies, 29,000 z ≥ 2.2 quasars, and 140,000 stars, including 74,000 velocity measurements of 2580 stars for MARVELS.
The Astronomical Journal 08/2011; 142(3):72. · 4.03 Impact Factor
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Ashley J. Ross, Shirley Ho,
Antonio J. Cuesta,
Rita Tojeiro,
Will J. Percival,
David Wake,
Karen L. Masters,
Robert C. Nichol,
Adam D. Myers,
Fernando de Simoni, [......],
Beatriz Ramos,
Ariel Sanchez,
Edward F. Schlafly,
David J. Schlegel,
Donald P. Schneider,
Ramin Skibba,
Daniel Thomas,
Benjamin A. Weaver,
Martin White,
Idit Zehavi
[show abstract]
[hide abstract]
ABSTRACT: We investigate the effects of potential sources of systematic error on the
angular and photometric redshift, z_phot, distributions of a sample of redshift
0.4 < z < 0.7 massive galaxies whose selection matches that of the Baryon
Oscillation Spectroscopic Survey (BOSS) constant mass sample. Utilizing over
112,778 BOSS spectra as a training sample, we produce a photometric redshift
catalog for the galaxies in the SDSS DR8 imaging area that, after masking,
covers nearly one quarter of the sky (9,913 square degrees). We investigate
fluctuations in the number density of objects in this sample as a function of
Galactic extinction, seeing, stellar density, sky background, airmass,
photometric offset, and North/South Galactic hemisphere. We find that the
presence of stars of comparable magnitudes to our galaxies (which are not
traditionally masked) effectively remove area. Failing to correct for such
stars can produce systematic errors on the measured angular auto-correlation
function, w, that are larger than its statistical uncertainty. We describe how
one can effectively mask for the presence of the stars, without removing any
galaxies from the sample, and minimize the systematic error. Additionally, we
apply two separate methods that can be used to correct the systematic errors
imparted by any parameter that can be turned into a map on the sky. We find
that failing to properly account for varying sky background introduces a
systematic error on w. We measure w, in four z_phot slices of width 0.05
between 0.45 < z_phot < 0.65 and find that the measurements, after correcting
for the systematic effects of stars and sky background, are generally
consistent with a generic LambdaCDM model, at scales up to 60 degrees. At
scales greater than 3 degrees and z_phot > 0.5, the magnitude of the
corrections we apply are greater than the statistical uncertainty in w.
Monthly Notices of the Royal Astronomical Society 05/2011; 417(2). · 4.90 Impact Factor
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Nicholas P. Ross,
Adam D. Myers,
Erin S. Sheldon,
Christophe Yèche,
Michael A. Strauss,
Jo Bovy,
Jessica A. Kirkpatrick,
Gordon T. Richards,
Eric Aubourg,
Michael R. Blanton, [......],
David Schiminovich,
David J. Schlegel,
Donald P. Schneider,
Anže Slosar,
Nao Suzuki,
Jeremy L. Tinker,
David H. Weinberg,
Anya Weyant,
Martin White,
W. Michael Wood-Vasey
[show abstract]
[hide abstract]
ABSTRACT: The SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), a five-year
spectroscopic survey of 10,000 deg^2, achieved first light in late 2009. One of
the key goals of BOSS is to measure the signature of baryon acoustic
oscillations in the distribution of Ly-alpha absorption from the spectra of a
sample of ~150,000 z>2.2 quasars. Along with measuring the angular diameter
distance at z\approx2.5, BOSS will provide the first direct measurement of the
expansion rate of the Universe at z > 2. One of the biggest challenges in
achieving this goal is an efficient target selection algorithm for quasars over
2.2 < z < 3.5, where their colors overlap those of stars. During the first year
of the BOSS survey, quasar target selection methods were developed and tested
to meet the requirement of delivering at least 15 quasars deg^-2 in this
redshift range, out of 40 targets deg^-2. To achieve these surface densities,
the magnitude limit of the quasar targets was set at g <= 22.0 or r<=21.85.
While detection of the BAO signature in the Ly-alpha absorption in quasar
spectra does not require a uniform target selection, many other astrophysical
studies do. We therefore defined a uniformly-selected subsample of 20 targets
deg^-2, for which the selection efficiency is just over 50%. This "CORE"
subsample will be fixed for Years Two through Five of the survey. In this paper
we describe the evolution and implementation of the BOSS quasar target
selection algorithms during the first two years of BOSS operations. We analyze
the spectra obtained during the first year. 11,263 new z>2.2 quasars were
spectroscopically confirmed by BOSS. Our current algorithms select an average
of 15 z > 2.2 quasars deg^-2 from 40 targets deg^-2 using single-epoch SDSS
imaging. Multi-epoch optical data and data at other wavelengths can further
improve the efficiency and completeness of BOSS quasar target selection.
[Abridged]
05/2011;
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Anže Slosar,
Andreu Font-Ribera,
Matthew M. Pieri,
James Rich,
Jean-Marc Le Goff,
Éric Aubourg,
Jon Brinkmann,
Nicolas Busca,
Bill Carithers,
Romain Charlassier, [......],
Yodovina Piškur,
Emmanuel Rollinde,
Nicholas P. Ross,
David J. Schlegel,
Donald P. Schneider,
Erin Sheldon,
Benjamin A. Weaver,
David H. Weinberg,
Christophe Yeche,
Donald G. York
[show abstract]
[hide abstract]
ABSTRACT: Using a sample of approximately 14,000 z>2.1 quasars observed in the first
year of the Baryon Oscillation Spectroscopic Survey (BOSS), we measure the
three-dimensional correlation function of absorption in the Lyman-alpha forest.
The angle-averaged correlation function of transmitted flux (F = exp(-tau)) is
securely detected out to comoving separations of 60 Mpc/h, the first detection
of flux correlations across widely separated sightlines. A quadrupole
distortion of the redshift-space correlation function by peculiar velocities,
the signature of the gravitational instability origin of structure in the
Lyman-alpha forest, is also detected at high significance. We obtain a good fit
to the data assuming linear theory redshift-space distortion and linear bias of
the transmitted flux, relative to the matter fluctuations of a standard LCDM
cosmological model (inflationary cold dark matter with a cosmological
constant). At 95% confidence, we find a linear bias parameter 0.16<b<0.24 and
redshift-distortion parameter 0.44<beta<1.20, at central redshift z=2.25, with
a well constrained combination b(1+\beta)=0.336 +/- 0.012. The errors on beta
are asymmetric, with beta=0 excluded at over 5 sigma confidence level. The
value of beta is somewhat low compared to theoretical predictions, and our
tests on synthetic data suggest that it is depressed (relative to expectations
for the Lyman-alpha forest alone) by the presence of high column density
systems and metal line absorption. These results set the stage for cosmological
parameter determinations from three-dimensional structure in the Lyman-alpha
forest, including anticipated constraints on dark energy from baryon acoustic
oscillations.
04/2011;
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Daniel J. Eisenstein,
David H. Weinberg,
Eric Agol,
Hiroaki Aihara,
Carlos Allende Prieto,
Scott F. Anderson,
James A. Arns,
Eric Aubourg,
Stephen Bailey,
Eduardo Balbinot, [......],
John P. Wisniewski,
W. Michael Wood-Vasey,
Brian Yanny,
Naoki Yasuda,
Christophe Yeche,
Donald G. York,
Erick Young,
Gail Zasowski,
Idit Zehavi,
Bo Zhao
[show abstract]
[hide abstract]
ABSTRACT: Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II),
SDSS-III is a program of four spectroscopic surveys on three scientific themes:
dark energy and cosmological parameters, the history and structure of the Milky
Way, and the population of giant planets around other stars. In keeping with
SDSS tradition, SDSS-III will provide regular public releases of all its data,
beginning with SDSS DR8 (which occurred in Jan 2011). This paper presents an
overview of the four SDSS-III surveys. BOSS will measure redshifts of 1.5
million massive galaxies and Lya forest spectra of 150,000 quasars, using the
BAO feature of large scale structure to obtain percent-level determinations of
the distance scale and Hubble expansion rate at z<0.7 and at z~2.5. SEGUE-2,
which is now completed, measured medium-resolution (R=1800) optical spectra of
118,000 stars in a variety of target categories, probing chemical evolution,
stellar kinematics and substructure, and the mass profile of the dark matter
halo from the solar neighborhood to distances of 100 kpc. APOGEE will obtain
high-resolution (R~30,000), high signal-to-noise (S/N>100 per resolution
element), H-band (1.51-1.70 micron) spectra of 10^5 evolved, late-type stars,
measuring separate abundances for ~15 elements per star and creating the first
high-precision spectroscopic survey of all Galactic stellar populations (bulge,
bar, disks, halo) with a uniform set of stellar tracers and spectral
diagnostics. MARVELS will monitor radial velocities of more than 8000 FGK stars
with the sensitivity and cadence (10-40 m/s, ~24 visits per star) needed to
detect giant planets with periods up to two years, providing an unprecedented
data set for understanding the formation and dynamical evolution of giant
planet systems. (Abridged)
01/2011;
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SDSS-III collaboration: Hiroaki Aihara,
Carlos Allende Prieto,
Deokkeun An,
Scott F. Anderson,
Éric Aubourg,
Eduardo Balbinot,
Timothy C. Beers,
Andreas A. Berlind,
Steven J. Bickerton,
Dmitry Bizyaev, [......],
David A. Wake,
Ji Wang,
Benjamin A. Weaver,
David H. Weinberg,
Martin White,
Simon D. M. White,
Brian Yanny,
Naoki Yasuda,
Christophe Yeche,
Idit Zehavi
[show abstract]
[hide abstract]
ABSTRACT: The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with
new instrumentation and new surveys focused on Galactic structure and chemical
evolution, measurements of the baryon oscillation feature in the clustering of
galaxies and the quasar Ly alpha forest, and a radial velocity search for
planets around ~8000 stars. This paper describes the first data release of
SDSS-III (and the eighth counting from the beginning of the SDSS). The release
includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap,
bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a
third of the Celestial Sphere. All the imaging data have been reprocessed with
an improved sky-subtraction algorithm and a final, self-consistent photometric
recalibration and flat-field determination. This release also includes all data
from the second phase of the Sloan Extension for Galactic Understanding and
Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars
at both high and low Galactic latitudes. All the more than half a million
stellar spectra obtained with the SDSS spectrograph have been reprocessed
through an improved stellar parameters pipeline, which has better determination
of metallicity for high metallicity stars.
01/2011;
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Asantha Cooray,
Steve Eales,
Scott Chapman,
David L. Clements,
Olivier Dore,
Duncan Farrah,
Matt J. Jarvis,
Manoj Kaplinghat,
Mattia Negrello,
Alessandro Melchiorri, [......],
Licia Verde,
Aprajita Verma,
Patricio Vielva,
Marco P. Viero,
Baltasar Vila Vilaro,
Julie Wardlow,
Grant Wilson,
Edward L. Wright,
C. Kevin Xu,
Min S. Yun
[show abstract]
[hide abstract]
ABSTRACT: A large sub-mm survey with Herschel will enable many exciting science opportunities, especially in an era of wide-field optical and radio surveys and high resolution cosmic microwave background experiments. The Herschel-SPIRE Legacy Survey (HSLS), will lead to imaging data over 4000 sq. degrees at 250, 350, and 500 micron. Major Goals of HSLS are: (a) produce a catalog of 2.5 to 3 million galaxies down to 26, 27 and 33 mJy (50% completeness; 5 sigma confusion noise) at 250, 350 and 500 micron, respectively, in the southern hemisphere (3000 sq. degrees) and in an equatorial strip (1000 sq. degrees), areas which have extensive multi-wavelength coverage and are easily accessible from ALMA. Two thirds of the of the sources are expected to be at z > 1, one third at z > 2 and about a 1000 at z > 5. (b) Remove point source confusion in secondary anisotropy studies with Planck and ground-based CMB data. (c) Find at least 1200 strongly lensed bright sub-mm sources leading to a 2% test of general relativity. (d) Identify 200 proto-cluster regions at z of 2 and perform an unbiased study of the environmental dependence of star formation. (e) Perform an unbiased survey for star formation and dust at high Galactic latitude and make a census of debris disks and dust around AGB stars and white dwarfs. Comment: White paper supplement to the proposal submitted by the HSLS science team to ESA for Herschel open-time programs
07/2010;
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Asantha Cooray,
Steve Eales,
Scott Chapman,
David L. Clements,
Olivier Dore,
Duncan Farrah,
Matt J. Jarvis,
Manoj Kaplinghat,
Mattia Negrello,
Alessandro Melchiorri, [......],
Licia Verde,
Aprajita Verma,
Patricio Vielva,
Marco P. Viero,
Baltasar Vila Vilaro,
Julie Wardlow,
Grant Wilson,
Edward L. Wright,
C. Kevin Xu,
Min S. Yun
[show abstract]
[hide abstract]
ABSTRACT: A large sub-mm survey with Herschel will enable many exciting science
opportunities, especially in an era of wide-field optical and radio
surveys and high resolution cosmic microwave background experiments. The
Herschel-SPIRE Legacy Survey (HSLS), will lead to imaging data over 4000
sq. degrees at 250, 350, and 500 micron. Major Goals of HSLS are: (a)
produce a catalog of 2.5 to 3 million galaxies down to 26, 27 and 33 mJy
(50% completeness; 5 sigma confusion noise) at 250, 350 and 500 micron,
respectively, in the southern hemisphere (3000 sq. degrees) and in an
equatorial strip (1000 sq. degrees), areas which have extensive
multi-wavelength coverage and are easily accessible from ALMA. Two
thirds of the of the sources are expected to be at z > 1, one third
at z > 2 and about a 1000 at z > 5. (b) Remove point source
confusion in secondary anisotropy studies with Planck and ground-based
CMB data. (c) Find at least 1200 strongly lensed bright sub-mm sources
leading to a 2% test of general relativity. (d) Identify 200
proto-cluster regions at z of 2 and perform an unbiased study of the
environmental dependence of star formation. (e) Perform an unbiased
survey for star formation and dust at high Galactic latitude and make a
census of debris disks and dust around AGB stars and white dwarfs.
06/2010;
