Publications (8)0 Total impact
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J. Green,
P. Schechter,
C. Baltay,
R. Bean,
D. Bennett,
R. Brown,
C. Conselice,
M. Donahue,
X. Fan,
B. S. Gaudi, [......],
R. Cutri,
R. Goullioud,
K. Grady,
G. Helou,
C. Jackson,
J. Kruk,
M. Melton,
C. Peddie,
N. Rioux,
M. Seiffert
[show abstract]
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ABSTRACT: In December 2010, NASA created a Science Definition Team (SDT) for WFIRST,
the Wide Field Infra-Red Survey Telescope, recommended by the Astro 2010
Decadal Survey as the highest priority for a large space mission. The SDT was
chartered to work with the WFIRST Project Office at GSFC and the Program Office
at JPL to produce a Design Reference Mission (DRM) for WFIRST. Part of the
original charge was to produce an interim design reference mission by mid-2011.
That document was delivered to NASA and widely circulated within the
astronomical community. In late 2011 the Astrophysics Division augmented its
original charge, asking for two design reference missions. The first of these,
DRM1, was to be a finalized version of the interim DRM, reducing overall
mission costs where possible. The second of these, DRM2, was to identify and
eliminate capabilities that overlapped with those of NASA's James Webb Space
Telescope (henceforth JWST), ESA's Euclid mission, and the NSF's ground-based
Large Synoptic Survey Telescope (henceforth LSST), and again to reduce overall
mission cost, while staying faithful to NWNH. This report presents both DRM1
and DRM2.
08/2012;
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D. Schlegel,
F. Abdalla,
T. Abraham,
C Ahn,
C. Allende Prieto,
J. Annis,
E. Aubourg,
M. Azzaro,
S. Bailey. C. Baltay,
C. Baugh, [......],
B. A. Weaver, D. Weinberg,
M White,
M. Wood-Vasey,
J Yang,
X. Yang. Ch. Yeche,
N. Zakamska,
A. Zentner,
C. Zhai,
P Zhang
[show abstract]
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ABSTRACT: BigBOSS is a Stage IV ground-based dark energy experiment to study baryon
acoustic oscillations (BAO) and the growth of structure with a wide-area galaxy
and quasar redshift survey over 14,000 square degrees. It has been
conditionally accepted by NOAO in response to a call for major new
instrumentation and a high-impact science program for the 4-m Mayall telescope
at Kitt Peak. The BigBOSS instrument is a robotically-actuated, fiber-fed
spectrograph capable of taking 5000 simultaneous spectra over a wavelength
range from 340 nm to 1060 nm, with a resolution R = 3000-4800.
Using data from imaging surveys that are already underway, spectroscopic
targets are selected that trace the underlying dark matter distribution. In
particular, targets include luminous red galaxies (LRGs) up to z = 1.0,
extending the BOSS LRG survey in both redshift and survey area. To probe the
universe out to even higher redshift, BigBOSS will target bright [OII] emission
line galaxies (ELGs) up to z = 1.7. In total, 20 million galaxy redshifts are
obtained to measure the BAO feature, trace the matter power spectrum at smaller
scales, and detect redshift space distortions. BigBOSS will provide additional
constraints on early dark energy and on the curvature of the universe by
measuring the Ly-alpha forest in the spectra of over 600,000 2.2 < z < 3.5
quasars.
BigBOSS galaxy BAO measurements combined with an analysis of the broadband
power, including the Ly-alpha forest in BigBOSS quasar spectra, achieves a FOM
of 395 with Planck plus Stage III priors. This FOM is based on conservative
assumptions for the analysis of broad band power (kmax = 0.15), and could grow
to over 600 if current work allows us to push the analysis to higher wave
numbers (kmax = 0.3). BigBOSS will also place constraints on theories of
modified gravity and inflation, and will measure the sum of neutrino masses to
0.024 eV accuracy.
06/2011;
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M. Tegmark,
D. Eisenstein,
M Strauss, D. Weinberg,
M. Blanton,
J. Frieman,
M. Fukugita,
J. Gunn,
A Hamilton,
G. Knapp, [......],
C. Rockosi,
R. Scranton,
R. Sheth,
A. Stebbins,
C. Stoughton,
I. Szapudi,
D. Tucker,
D. Vanden Berk,
B. Yanny,
D. York
[show abstract]
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ABSTRACT: We measure the large-scale real-space power spectrum P(k) using luminous red galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS) and use this measurement to sharpen constraints on cosmological parameters from the Wilkinson Microwave Anisotropy Probe (WMAP). We employ a matrix-based power spectrum estimation method using Pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 20 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well-behaved window functions in the range 0.01h/Mpc < k < 0.2h/Mpc. Results from the LRG and main galaxy samples are consistent, with the former providing higher signal-to-noise. Our results are robust to omitting angular and radial density fluctuations and are consistent between different parts of the sky. They provide a striking confirmation of the predicted large-scale LCDM power spectrum. Combining only SDSS LRG and WMAP data places robust constraints on many cosmological parameters that complement prior analyses of multiple data sets. The LRGs provide independent cross-checks on Om and the baryon fraction in good agreement with WMAP. Within the context of flat LCDM models, our LRG measurements complement WMAP by sharpening the constraints on the matter density, the neutrino density and the tensor amplitude by about a factor of two, giving Omega_m=0.24+-0.02 (1 sigma), sum m_nu < 0.9 eV (95%) and r<0.3 (95%). Baryon oscillations are clearly detected and provide a robust measurement of the comoving distance to the median survey redshift z=0.35 independent of curvature and dark energy properties. Within the LCDM framework, our power spectrum measurement improves the evidence for spatial flatness, sharpening the curvature constraint Omega_tot=1.05+-0.05 from WMAP alone to Omega_tot=1.003+-0.010. Assuming Omega_tot=1, the equation of state parameter is constrained to w=-0.94+-0.09, indicating the potential for more ambitious future LRG measurements to provide precision tests of the nature of dark energy. All these constraints are essentially independent of scales k>0.1h/Mpc and associated nonlinear complications, yet agree well with more aggressive published analyses where nonlinear modeling is crucial.
09/2006;
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U. Seljak,
A. Makarov,
P. McDonald,
S Anderson,
N. Bahcall,
J. Brinkmann,
S. Burles,
R. Cen,
M Doi,
J. Gunn, [......],
S. Kent,
R. Lupton,
J. Munn,
R. Nichol,
J. Ostriker,
D. Schlegel,
M. Tegmark,
D. Van den Berk, D. Weinberg,
D. York
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ABSTRACT: We combine the constraints from the recent Ly-alpha forest and bias analysis of the SDSS with previous constraints from SDSS galaxy clustering, the latest supernovae, and WMAP . Combining WMAP and the lya we find for the primordial slope n_s=0.98\pm 0.02. We see no evidence of running, dn/d\ln k=-0.003\pm 0.010, a factor of 3 improvement over previous constraints. We also find no evidence of tensors, r<0.36 (95% c.l.). A positive correlation between tensors and primordial slope disfavors chaotic inflation type models with steep slopes: V \propto \phi^4 is outside the 3-sigma contour. For the amplitude we find sigma_8=0.90\pm 0.03 from the lyaf and WMAP alone. We find no evidence of neutrino mass: for the case of 3 massive neutrino families with an inflationary prior, \sum m_{\nu}<0.42eV and the mass of lightest neutrino is m_1<0.13eV at 95% c.l. For the 3 massless + 1 massive neutrino case we find m_{\nu}<0.79eV for the massive neutrino, excluding at 95% c.l. all neutrino mass solutions compatible with the LSND results. We explore dark energy constraints in models with a fairly general time dependence of dark energy equation of state, finding Omega_lambda=0.72\pm 0.02, w(z=0.3)=-0.98^{+0.10}_{-0.12}, the latter changing to w(z=0.3)=-0.92^{+0.09}_{-0.10} if tensors are allowed. We find no evidence for variation of the equation of state with redshift, w(z=1)=-1.03^{+0.21}_{-0.28}. These results rely on the current understanding of the lyaf and other probes, which need to be explored further both observationally and theoretically, but extensive tests reveal no evidence of inconsistency among different data sets used here.
08/2004;
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M. Tegmark,
M. Blanton,
M Strauss,
F. Hoyle,
D. Schlegel,
R. Scoccimarro,
M Vogeley, D. Weinberg,
I. Zehavi,
A. Berlind, [......],
R. Scranton,
U. Seljak,
R. Sheth,
A. Stebbins,
A. Szalay,
I. Szapudi,
L. Verde,
Y Xu,
others,
for the SDSS Collaboration
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ABSTRACT: We measure the large-scale real-space power spectrum P(k) using a sample of 205,443 galaxies from the Sloan Digital Sky Survey, covering 2417 square degrees with mean redshift z~0.1. We employ a matrix-based method using pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 22 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well-behaved window functions in the range 0.02 h/Mpc < k < 0.3h/Mpc. We pay particular attention to modeling, quantifying and correcting for potential systematic errors, nonlinear redshift distortions and the artificial red-tilt caused by luminosity-dependent bias. Our final result is a measurement of the real-space matter power spectrum P(k) up to an unknown overall multiplicative bias factor. Our calculations suggest that this bias factor is independent of scale to better than a few percent for k<0.1h/Mpc, thereby making our results useful for precision measurements of cosmological parameters in conjunction with data from other experiments such as the WMAP satellite. As a simple characterization of the data, our measurements are well fit by a flat scale-invariant adiabatic cosmological model with h Omega_m =0.201+/- 0.017 and L* galaxy sigma_8=0.89 +/- 0.02 when fixing the baryon fraction Omega_b/Omega_m=0.17 and the Hubble parameter h=0.72; cosmological interpretation is given in a companion paper.
11/2003;
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M. Tegmark,
M Strauss,
M. Blanton,
K. Abazajian,
S. Dodelson,
H. Sandvik,
X Wang, D. Weinberg,
I. Zehavi,
N. Bahcall, [......],
J. Ostriker,
A. Pope,
R. Scranton,
U. Seljak,
R. Sheth,
A. Stebbins,
A. Szalay,
I. Szapudi,
Y Xu,
others
[show abstract]
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ABSTRACT: 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.
11/2003;
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M. R. Blanton,
J. Dalcanton,
D. Eisenstein,
J. Loveday,
M. Strauss,
M. SubbaRao, D. Weinberg,
J. Annis,
N. Bahcall,
M. Bernardi, [......],
Y. Snir,
C. Stubbs,
A. Szalay,
C. Tremonti,
D. Tucker,
A. Uomoto,
D. E. Vanden Berk,
P. Waddell,
B. Yanny,
Sloan Digital Sky Survey Collaboration
[show abstract]
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ABSTRACT: The Sloan Digital Sky Survey (SDSS) already has compiled one of the
largest redshift samples of galaxies selected from CCD images. From a
portion of this data, consisting of around 11,000 objects complete to
r=17.6, over about 140 square degrees, we have calculated the luminosity
function of galaxies and the luminosity density of the universe. We do
so using five optical bandpasses: u, g, r, i, and z. We calculate the
correlation of r-band luminosity with half-light surface brightness,
intrinsic g-r color, and morphology, showing that high surface
brightness, red, early-type galaxies are on average more luminous than
low surface brightness, blue, late-type galaxies, in agreement with
previous results. If we convert our results into the Las Campanas
Redshift Survey (LCRS) version of the R-band, we find baout 2.5 times
the luminosity density found in the LCRS. If we convert our results to
the bj band, we find about 1.4 times the luminosity found in
the Two-degree Field Galaxy Redshift Survey (2dFGRS). When we measure
the magnitudes of SDSS galaxies using the same isophotal limits and
including the other selection effects of these two surveys, we obtain
luminosity functions consistent with theirs.
11/2000; 32:1443.
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ABSTRACT: We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability theory, implies that the observed large-scale structures and large-scale flows were produced by the action of gravity. This assumption is false, in that there exist non-gravitational theories that pass the reconstruction tests and gravitational theories with certain forms of biased galaxy formation that fail them. Gravitational instability theory predicts specific correlations between large-scale velocity and mass density fields, but the same correlations arise in any model where (a) structures in the galaxy distribution grow from homogeneous initial conditions in a way that satisfies the continuity equation, and (b) the present-day velocity field is irrotational and proportional to the time-averaged velocity field. We demonstrate these assertions using analytical arguments and N-body simulations of gravitational and non-gravitational models. We also show examples of gravitational and non-gravitational models that {\it fail} reconstruction tests because galaxy formation is modulated (``biased'') in a way that violates the continuity equation. We discuss the relation between the value of $\Omega$ inferred from velocity-density comparisons and the true cosmological value. Comment: plain tex, 34 pp; postscript version w/ 17 figures available by anonymous ftp; to appear in ApJ; IAS preprint #93-67
11/1993;
