Albert Stebbins
A5005110872- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Scientific Research and Discoveries
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Relativity and Gravitational Theory
- Particle physics theoretical and experimental studies
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Radio Wave Propagation Studies
- Computational Physics and Python Applications
- History and Developments in Astronomy
- Black Holes and Theoretical Physics
- Antenna Design and Optimization
- Neutrino Physics Research
- Medical Imaging Techniques and Applications
- Astrophysics and Star Formation Studies
Fermi National Accelerator Laboratory
2015-2024
University of Wisconsin–Madison
2018
Institut d'Astrophysique de Paris
2006
University of Chicago
1996-2005
Campbell Collaboration
2005
Columbia University
1997
University of Sussex
1994
Electronics for Imaging (United States)
1994
NASA Astrobiology Institute
1992-1993
Brown University
1990
We measure cosmological parameters using the three-dimensional power spectrum $P(k)$ from over 200 000 galaxies in Sloan Digital Sky Survey (SDSS) combination with Wilkinson Microwave Anisotropy Probe (WMAP) and other data. Our results are consistent a ``vanilla'' flat adiabatic cold dark matter model constant without tilt ${(n}_{s}=1),$ running tilt, tensor modes, or massive neutrinos. Adding SDSS information more than halves WMAP-only error bars on some parameters, tightening...
We measure the large-scale real-space power spectrum P(k) using a sample of 205,443 galaxies from Sloan Digital Sky Survey, covering 2417 square degrees with mean redshift z~0.1. employ matrix-based method pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 22 k-bands both clustering and its anisotropy due to redshift-space distortions, narrow well-behaved window functions range 0.02 h/Mpc < k 0.3h/Mpc. pay particular attention modeling, quantifying...
We measure the large-scale real-space power spectrum $P(k)$ using luminous red galaxies (LRGs) in Sloan Digital Sky Survey (SDSS) and use this measurement to sharpen constraints on cosmological parameters from Wilkinson Microwave Anisotropy Probe (WMAP). employ a matrix-based estimation method Pseudo-Karhunen-Lo\`eve eigenmodes, producing uncorrelated minimum-variance measurements 20 $k$-bands of both clustering its anisotropy due redshift-space distortions, with narrow well-behaved window...
We present a formalism for analyzing full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over set spherical harmonics to give multipole moments two-point correlation function. Polarization, which is described second-rank tensor, can be treated analogously in appropriate tensor harmonics. provide expressions complete scalar metric perturbations. Four sets completely describe isotropic correlations; perturbations one...
We explore the cosmological implications of an ultralight pseudo Nambu-Goldstone boson. With global spontaneous symmetry breaking scale $f\ensuremath{\simeq}{10}^{18}\mathrm{GeV}$ and explicit comparable to Mikheyev-Smirnov-Wolfenstein neutrino masses, $M\ensuremath{\sim}{10}^{\ensuremath{-}3}\mathrm{eV}$, such a field, which acquires mass ${m}_{\ensuremath{\varphi}}\ensuremath{\sim}{M}^{2}/f\ensuremath{\sim}{H}_{0}$, would currently dominate energy density Universe. The field acts as...
A formalism for describing an all-sky map of the polarization cosmic microwave background is presented. The pattern on sky can be decomposed into two geometrically distinct components. One these components not coupled to density inhomogeneities. nonzero amplitude this component only caused by tensor or vector metric perturbations. This allows unambiguous identification long-wavelength gravity waves large-scale vortical flows at time last scattering.
We present the first measurements of clustering in Sloan Digital Sky Survey (SDSS) galaxy redshift survey. Our sample consists 29,300 galaxies with redshifts 5,700 km/s < cz 39,000 km/s, distributed several long but narrow (2.5-5 degree) segments, covering 690 square degrees. For full, flux-limited sample, redshift-space correlation length is approximately 8 Mpc/h. The two-dimensional function ξ(r_p,π) shows clear signatures both small-scale, ``fingers-of-God'' distortion caused by...
We use 26×106 galaxies from the Dark Energy Survey (DES) Year 1 shape catalogs over 1321 deg2 of sky to produce most significant measurement cosmic shear in a galaxy survey date. constrain cosmological parameters both flat ΛCDM and wCDM models, while also varying neutrino mass density. These results are shown be robust using two independent catalogs, photo-z calibration methods, analysis pipelines blind analysis. find 3.5% fractional uncertainty on σ8(Ωm/0.3)0.5=0.782+0.027−0.027 at 68%...
Abstract We present the Dark Energy Camera (DECam) discovery of optical counterpart first binary neutron star merger detected through gravitational-wave emission, GW170817. Our observations commenced 10.5 hr post-merger, as soon localization region became accessible from Chile. imaged 70 deg 2 in i and z bands, covering 93% initial integrated probability, to a depth necessary identify likely counterparts (e.g., kilonova). At 11.4 post-merger we bright transient located nucleus NGC 4993 at...
Abstract There is controversy surrounding the origin and evolution of our universe's largest supermassive black holes (SMBHs). In this study, we consider possibility that some these formed from direct collapse primordial density perturbations. Since mass a hole limited by size cosmological horizon at time collapse, SMBHs must form rather late, are naively in conflict with constraints CMB spectral distortions. These limits can be avoided, however, if distribution curvature perturbations...
The angular distribution of galaxies encodes a wealth information about large scale structure. Ultimately, the Sloan Digital Sky Survey (SDSS) will record positions order 10^8 in five bands, adding significantly to cosmological constraints. This is first series papers analyzing rectangular stripe 2.5x90 degrees from early SDSS data. We present correlation function for four separate magnitude bins on scales ranging 0.003 15 degrees. Much focus this paper potential systematic effects. show...
view Abstract Citations (183) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Topology of Microwave Background Fluctuations: Theory Gott, J. Richard, III ; Park, Changbom Juszkiewicz, Roman Bies, William E. Bennett, David P. Bouchet, Francois R. Stebbins, Albert Topological measures are used to characterize the microwave background temperature fluctuations produced by "standard" scenarios (Gaussian) and cosmic strings (non-Gaussian). Three...
In this paper, we describe the spherical harmonic transit telescope through use of a novel formalism for analysis radio telescopes. This all-sky approach bypasses curved-sky complications traditional interferometry and so is particularly well-suited to wide-field interferometers. It enables compact computationally efficient representations data its statistics, which allow new ways approaching important problems like map-making foreground removal. particular, show how it Karhunen-Loève...
The blackbody nature of the cosmic microwave background (CMB) radiation spectrum is used in a modern test Copernican principle. reionized universe serves as mirror to reflect CMB photons, thereby permitting view ourselves and local gravitational potential. By comparing with measurements spectrum, limit placed on possibility that we occupy privileged location, residing at center large void. Hubble diagram inferred from lines sight originating void may be misinterpreted indicate acceleration....
In this paper we continue to develop the $m$-mode formalism, a technique for efficient and optimal analysis of wide-field transit radio telescopes, targeted at 21 cm cosmology. We extend formalism give an accurate treatment polarized sky, fully accounting effects polarization leakage cross polarization. use geometry measured set visibilities project down pure temperature modes on serving as significant compression, effective first filter contaminants. As in our previous work, with...
(abridged) We present measurements of galaxy-galaxy lensing from early commissioning imaging data the Sloan Digital Sky Survey (SDSS). measure a mean tangential shear around stacked sample foreground galaxies in three bandpasses out to angular radii 600'', detecting signal at very high statistical significance. The profile is well described by power-law. A variety rigorous tests demonstrate reality gravitational and confirm uncertainty estimates. interpret our results modeling mass...
Early photometric data from the Sloan Digital Sky Survey (SDSS) contain angular positions for 1.5 million galaxies. In companion papers, correlation function $w(\theta)$ and 2D power spectrum $C_l$ of these galaxies are presented. Here we invert Limber's equation to extract 3D results. We accomplish this using an estimate $dn/dz$, redshift distribution in four different magnitude slices SDSS catalog. The resulting estimates agree with each other previous over a range wavenumbers $0.03 <...
We present a weak lensing analysis of the Coma Cluster using Sloan Digital Sky Survey (SDSS) Data Release Five. Complete imaging ~ 200 square degree region is used to measure tangential shear this cluster. The fit an NFW model and we find virial radius r_{200}=1.99_{-0.22}^{+0.21}h^{-1}Mpc which corresponds mass M_{200}=1.88_{-0.56}^{+0.65}\times10^{15}h^{-1}M_{\odot}. additionally compare our measurement derived dynamical techniques, they are in agreement. This lowest redshift, largest...
Baryon acoustic oscillations (BAO) provide a robust standard ruler with which to measure the acceleration of Universe. The BAO feature has so far been detected in optical galaxy surveys. Intensity mapping neutral hydrogen emission ground-based radio telescope provides another promising window for measuring at redshifts order unity relatively low cost. While cylindrical (CRT) proposed these measurements will have excellent redshift resolution, it suffer from poor angular resolution (a few...
view Abstract Citations (135) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmic String Wakes Stebbins, Albert ; Veeraraghavan, Shoba Brandenberger, Robert Silk, Joseph Turok, Neil Accretion of matter onto wakes left behind by horizon-sized pieces cosmic string is investigated, and the effects on large-scale structure universe are determined. cold wakes, a long fluids with finite velocity dispersion or sound speeds, interactions between...