Eiichiro Komatsu - Dept. of Astronomy, Univ. of Texas, Austin

Eiichiro Komatsu
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Name
Eiichiro Komatsu
Affiliation
Dept. of Astronomy, Univ. of Texas, Austin
City
Austin
Country
United States

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Cosmology and Nongalactic Astrophysics (50)
 
General Relativity and Quantum Cosmology (10)
 
High Energy Physics - Theory (9)
 
High Energy Physics - Phenomenology (8)
 
High Energy Astrophysical Phenomena (7)
 
Astrophysics of Galaxies (6)
 
Instrumentation and Methods for Astrophysics (3)

Publications Authored By Eiichiro Komatsu

We show that measurements of the fluctuations in the near-infrared background (NIRB) from the AKARI satellite can be explained by faint galaxy populations at low redshifts. We demonstrate this using reconstructed images from deep galaxy catalogs (HUGS/S-CANDELS) and two independent galaxy population models. In all cases, we find that the NIRB fluctuations measured by AKARI are consistent with faint galaxies and there is no need for a contribution from unknown populations. Read More

The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Read More

2016Aug
Authors: Naoyuki Tamura, Naruhisa Takato, Atsushi Shimono, Yuki Moritani, Kiyoto Yabe, Yuki Ishizuka, Akitoshi Ueda, Yukiko Kamata, Hrand Aghazarian, Stephane Arnouts, Gabriel Barban, Robert H. Barkhouser, Renato C. Borges, David F. Braun, Michael A. Carr, Pierre-Yves Chabaud, Yin-Chang Chang, Hsin-Yo Chen, Masashi Chiba, Richard C. Y. Chou, You-Hua Chu, Judith G. Cohen, Rodrigo P. de Almeida, Antonio C. de Oliveira, Ligia S. de Oliveira, Richard G. Dekany, Kjetil Dohlen, Jesulino B. dos Santos, Leandro H. dos Santos, Richard S. Ellis, Maximilian Fabricius, Didier Ferrand, Decio Ferreira, Mirek Golebiowski, Jenny E. Greene, Johannes Gross, James E. Gunn, Randolph Hammond, Albert Harding, Murdock Hart, Timothy M. Heckman, Christopher M. Hirata, Paul Ho, Stephen C. Hope, Larry Hovland, Shu-Fu Hsu, Yen-Shan Hu, Ping-Jie Huang, Marc Jaquet, Yipeng Jing, Jennifer Karr, Masahiko Kimura, Matthew E. King, Eiichiro Komatsu, Vincent Le Brun, Olivier Le Fevre, Arnaud Le Fur, David Le Mignant, Hung-Hsu Ling, Craig P. Loomis, Robert H. Lupton, Fabrice Madec, Peter Mao, Lucas S. Marrara, Claudia Mendes de Oliveira, Yosuke Minowa, Chaz N. Morantz, Hitoshi Murayama, Graham J. Murray, Youichi Ohyama, Joseph Orndorff, Sandrine Pascal, Jefferson M. Pereira, Daniel J. Reiley, Martin Reinecke, Andreas Ritter, Mitsuko Roberts, Mark A. Schwochert, Michael D. Seiffert, Stephen A. Smee, Laerte Sodre Jr., David N. Spergel, Aaron J. Steinkraus, Michael A. Strauss, Christian Surace, Yasushi Suto, Nao Suzuki, John Swinbank, Philip J. Tait, Masahiro Takada, Tomonori Tamura, Yoko Tanaka, Laurence Tresse, Orlando Verducci Jr., Didier Vibert, Clement Vidal, Shiang-Yu Wang, Chih-Yi Wen, Chi-Hung Yan, Naoki Yasuda

PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1. Read More

2015Oct

We present a Bayesian approach to the redshift classification of emission-line galaxies when only a single emission line is detected spectroscopically. We consider the case of surveys for high-redshift Lyman-alpha-emitting galaxies (LAEs), which have traditionally been classified via an inferred rest-frame equivalent width (EW) greater than 20 angstrom. Our Bayesian method relies on known prior probabilities in measured emission-line luminosity functions and equivalent width distributions for the galaxy populations, and returns the probability that an object in question is an LAE given the characteristics observed. Read More

We calculate the one-point probability density distribution functions (PDF) and the power spectra of the thermal and kinetic Sunyaev-Zeldovich (tSZ and kSZ) effects and the mean Compton Y parameter using the Magneticum Pathfinder simulations, state-of-the-art cosmological hydrodynamical simulations of a large cosmological volume of (896 Mpc/h)^3. These simulations follow in detail the thermal and chemical evolution of the intracluster medium as well as the evolution of super-massive black holes and their associated feedback processes. We construct full-sky maps of tSZ and kSZ from the light-cones out to z=0. Read More

Strong lensing time-delay systems constrain cosmological parameters via the so-called time-delay distance and the angular diameter distance to the lens. In previous studies, only the former information was used. In this paper, we show that the cosmological constraints improve significantly when the latter information is also included. Read More

Non-thermal pressure in galaxy clusters leads to underestimation of the mass of galaxy clusters based on hydrostatic equilibrium with thermal gas pressure. This occurs even for dynamically relaxed clusters that are used for calibrating the mass-observable scaling relations. We show that the analytical model for non-thermal pressure developed in Shi & Komatsu 2014 can correct for this so-called 'hydrostatic mass bias', if most of the non-thermal pressure comes from bulk and turbulent motions of gas in the intracluster medium. Read More

Cosmological transverse momentum fields, whose directions are perpendicular to Fourier wave vectors, induce temperature anisotropies in the cosmic microwave background via the kinetic Sunyaev-Zeldovich (kSZ) effect. The transverse momentum power spectrum contains the four-point function of density and velocity fields, $\langle\delta\delta v v\rangle$. In the post-reionization epoch, nonlinear effects dominate in the power spectrum. Read More

We report on the first measurement of the three-point function with the position-dependent correlation function from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 10 CMASS sample. This new observable measures the correlation between two-point functions of galaxy pairs within different subvolumes, $\hat{\xi}({\rm r},{\rm r}_L)$, where ${\rm r}_L$ is the location of a subvolume, and the corresponding mean overdensities, $\bar{\delta}({\rm r}_L)$. This correlation, which we call the "integrated three-point function", $i\zeta(r)=\langle\hat{\xi}({\rm r},{\rm r}_L)\bar{\delta}({\rm r}_L)\rangle$, measures a three-point function of two short- and one long-wavelength modes, and is generated by nonlinear gravitational evolution and possibly also by the physics of inflation. Read More

We show that in a certain, angle-averaged squeezed limit, the $N$-point function of matter is related to the response of the matter power spectrum to a long-wavelength density perturbation, $P^{-1}d^nP(k|\delta_L)/d\delta_L^n|_{\delta_L=0}$, with $n=N-2$. By performing N-body simulations with a homogeneous overdensity superimposed on a flat Friedmann-Robertson-Lema\^itre-Walker (FRLW) universe using the \emph{separate universe} approach, we obtain measurements of the nonlinear matter power spectrum response up to $n=3$, which is equivalent to measuring the fully nonlinear matter $3-$ to $5-$point function in this squeezed limit. The sub-percent to few percent accuracy of those measurements is unprecedented. Read More

Damping of magnetic fields via ambipolar diffusion and decay of magnetohydrodynamical (MHD) turbulence in the post decoupling era heats the intergalactic medium (IGM). Delayed recombination of hydrogen atoms in the IGM yields an optical depth to scattering of the cosmic microwave background (CMB). The optical depth generated at $z\gg 10$ does not affect the "reionization bump" of the CMB polarization power spectrum at low multipoles, but affects the temperature and polarization power spectra at high multipoles. Read More

The presence of a light vector field coupled to a scalar field during inflation makes a distinct prediction: the observed correlation functions of the cosmic microwave background (CMB) become statistically anisotropic. We study the implications of the current bound on statistical anisotropy derived from the Planck 2013 CMB temperature data for such a model. The previous calculations based on the attractor solution indicate that the magnitude of anisotropy in the power spectrum is proportional to $N^2$, where $N$ is the number of $e$-folds of inflation counted from the end of inflation. Read More

The distance-redshift relation plays a fundamental role in constraining cosmological models. In this paper, we show that measurements of positions and time delays of strongly lensed images of a background galaxy, as well as those of the velocity dispersion and mass profile of a lens galaxy, can be combined to extract the angular diameter distance of the lens galaxy. Physically, as the velocity dispersion and the time delay give a gravitational potential ($GM/r$) and a mass ($GM$) of the lens, respectively, dividing them gives a physical size ($r$) of the lens. Read More

The large-scale statistics of observables such as the galaxy density are chiefly determined by their dependence on the local coarse-grained matter density. This dependence can be measured directly and efficiently in N-body simulations by using the fact that a uniform density perturbation with respect to some fiducial background cosmology is equivalent to modifying the background and including curvature, i.e. Read More

Turbulent gas motion inside galaxy clusters provides a non-negligible non-thermal pressure support to the intracluster gas. If not corrected, it leads to a systematic bias in the estimation of cluster masses from X-ray and Sunyaev-Zel'dovich (SZ) observations assuming hydrostatic equilibrium, and affects interpretation of measurements of the SZ power spectrum and observations of cluster outskirts from ongoing and upcoming large cluster surveys. Recently, Shi & Komatsu developed an analytical model for predicting the radius, mass, and redshift dependence of the non-thermal pressure contributed by the kinetic random motions of intracluster gas sourced by the cluster mass growth. Read More

Bayesian model comparison penalizes models with more free parameters that are allowed to vary over a wide range, and thus offers the most robust method to decide whether some given data require new parameters. In this paper, we ask a simple question: do current cosmological data require extensions of the simplest single-field inflation models? Specifically, we calculate the Bayesian evidence of a totally anti-correlated isocurvature perturbation and a running spectral index of the scalar curvature perturbation. These parameters are motivated by recent claims that the observed temperature anisotropy of the cosmic microwave background on large angular scales is too low to be compatible with the simplest inflation models. Read More

The Wilkinson Microwave Anisotropy Probe (WMAP) mapped the distribution of temperature and polarization over the entire sky in five microwave frequency bands. These full-sky maps were used to obtain measurements of temperature and polarization anisotropy of the cosmic microwave background with the unprecedented accuracy and precision. The analysis of two-point correlation functions of temperature and polarization data gives determinations of the fundamental cosmological parameters such as the age and composition of the universe, as well as the key parameters describing the physics of inflation, which is further constrained by three-point correlation functions. Read More

The influence of large-scale density fluctuations on structure formation on small scales is described by the three-point correlation function (bispectrum) in the so-called "squeezed configurations," in which one wavenumber, say $k_3$, is much smaller than the other two, i.e., $k_3\ll k_1\approx k_2$. Read More

Non-thermal pressure in the intracluster gas has been found ubiquitously in numerical simulations, and observed indirectly. In this paper we develop an analytical model for intracluster non-thermal pressure in the virial region of relaxed clusters. We write down and solve a first-order differential equation describing the evolution of non-thermal velocity dispersion. Read More

Soft limits of $N$-point correlation functions, in which one wavenumber is much smaller than the others, play a special role in constraining the physics of inflation. Anisotropic sources such as a vector field during inflation generate distinct angular dependence in all these correlators. In this paper we focus on the four-point correlator (the trispectrum $T$). Read More

Cross-correlating gamma-ray maps with locations of galaxies in the low-redshift Universe vastly increases sensitivity to signatures of annihilation of dark matter particles. Low-redshift galaxies are ideal targets, as the largest contribution to anisotropy in the gamma-ray sky from annihilation comes from $z\lesssim 0.1$, where we expect minimal contributions from astrophysical sources such as blazars. Read More

Temperature anisotropy of the cosmic microwave background offers a test of the fundamental symmetry of spacetime during cosmic inflation. Violation of rotational symmetry yields a distinct signature in the power spectrum of primordial fluctuations as $P({\mathbf k})=P_0(k)[1+g_*(\hat{\mathbf k}\cdot\hat{\mathbf E}_{\rm cl})^2]$, where $\hat{\mathbf E}_{\rm cl}$ is a preferred direction in space and $g_*$ is an amplitude. Using the \textit{Planck} 2013 temperature maps, we find no evidence for violation of rotational symmetry, $g_*=0. Read More

Observational limits on $y$- and $\mu$-type distortions can constrain properties of magnetic fields in the early universe. For a Gaussian, random, and non-helical field, $\mu$ and $y$ are calculated a function of the present-day strength of the field, $B_0$, smoothed over a certain Gaussian width, $k_c^{-1}$, and spectral index, $n_B$, defined by $P_B(k)\propto k^{n_B}$. For $n_B=-2. Read More

We calculate the bispectrum of primordial curvature perturbations, \zeta, generated during "open inflation." Inflation occurs inside a bubble nucleated via quantum tunneling from the background false vacuum state. Our universe lives inside the bubble, which can be described as a Friedman-Lema\^itre-Robertson-Walker (FLRW) universe with negative spatial curvature, undergoing slow-roll inflation. Read More

In non-attractor single-field inflation models producing a scale-invariant power spectrum, the curvature perturbation on super-horizon scales grows as ${\cal R}\propto a^3$. This is so far the only known class of self-consistent single-field models with a Bunch-Davies initial state that can produce a large squeezed-limit bispectrum violating Maldacena's consistency relation. Given the importance of this result, we calculate the bispectrum with three different methods: using quantum field theory calculations in two different gauges, and classical calculations (the $\delta N$ formalism). Read More

Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large volume (e.g. Read More

The Integrated Sachs-Wolfe (ISW) effect produces a secondary temperature anisotropy of CMB. The main contribution comes from z<2, where dark energy leads to a decay of potentials. As the same photons are gravitationally lensed by these decaying potentials, there exists a high degree of correlation between the ISW effect and CMB lensing, leading to a non-zero three-point correlation (bispectrum) of the observed temperature anisotropy. Read More

The bispectrum of primordial curvature perturbations in the squeezed configuration, in which one wavenumber, $k_3$, is much smaller than the other two, $k_3\ll k_1\approx k_2$, plays a special role in constraining the physics of inflation. In this paper we study a new phenomenological signature in the squeezed-limit bispectrum: namely, the amplitude of the squeezed-limit bispectrum depends on an angle between ${\bf k}_1$ and ${\bf k}_3$ such that $B_\zeta(k_1, k_2, k_3) \to 2 \sum_L c_L P_L(\hat{\bf k}_1 \cdot \hat{\bf k}_3) P_\zeta(k_1)P_\zeta(k_3)$, where $P_L$ are the Legendre polynomials. While $c_0$ is related to the usual local-form $f_{\rm NL}$ parameter as $c_0=6f_{\rm NL}/5$, the higher-multipole coefficients, $c_1$, $c_2$, etc. Read More

Annihilation of dark matter particles in cosmological halos (including a halo of the Milky Way) contributes to the diffuse gamma-ray background (DGRB). As this contribution will appear anisotropic in the sky, one can use the angular power spectrum of anisotropies in DGRB to constrain properties of dark matter particles. By comparing the updated analytic model of the angular power spectrum of DGRB from dark matter annihilation with the power spectrum recently measured from the 22-month data of Fermi Large Area Telescope (LAT), we place upper limits on the annihilation cross section of dark matter particles as a function of dark matter masses. Read More

We calculate the angular power spectrum of the Cosmic Microwave Background (CMB) temperature fluctuations induced by the kinetic Sunyaev-Zel'dovich (kSZ) effect from the epoch of reionization (EOR). We use detailed N-body+radiative transfer simulations to follow inhomogeneous reionization of the intergalactic medium (IGM). For the first time we take into account the "self-regulation" of reionization: star formation in low-mass dwarf galaxies (10^8 M_\sun \lesssim M \lesssim 10^9 M_\sun) or minihalos (10^5 M_\sun \lesssim M \lesssim 10^8 M_\sun) is suppressed if these halos form in the regions that were already ionized or Lyman-Werner dissociated. Read More

Large surveys for Lyman-alpha emitting (LAE) galaxies have been proposed as a new method for measuring clustering of the galaxy population at high redshift with the goal of determining cosmological parameters. However, Lyman-alpha radiative transfer effects may modify the observed clustering of LAE galaxies in a way that mimics gravitational effects, potentially reducing the precision of cosmological constraints. For example, the effect of the linear redshift-space distortion on the power spectrum of LAE galaxies is potentially degenerate with Lyman-alpha radiative transfer effects owing to the dependence of observed flux on intergalactic medium velocity gradients. Read More

Large-scale reionization simulations are described which combine the results of cosmological N-body simulations that model the evolving density and velocity fields and identify the galactic halo sources, with ray-tracing radiative transfer calculations which model the nonequilibrium ionization of the intergalactic medium. These simulations have been used to predict some of the signature effects of reionization on cosmic radiation backgrounds, including the CMB, near-IR, and redshifted 21cm backgrounds. We summarize some of our recent progress in this work, and address the question of whether observations of such signature effects can be used to distinguish the relative contributions of galaxies of different masses to reionization. Read More

Precise understanding of nonlinear evolution of cosmological perturbations during inflation is necessary for the correct interpretation of measurements of non-Gaussian correlations in the cosmic microwave background and the large-scale structure of the universe. The "{\delta}N formalism" is a popular and powerful technique for computing non-linear evolution of cosmological perturbations on large scales. In particular, it enables us to compute the curvature perturbation, {\zeta}, on large scales without actually solving perturbed field equations. Read More

We investigate the phenomenological consequences of a modification of the initial state of a single inflationary field. While single-field inflation with the standard Bunch-Davies initial vacuum state does not generally produce a measurable three-point function (bispectrum) in the squeezed configuration, allowing for a non-standard initial state produces an exception. Here, we calculate the signature of an initial state modification in single-field slow-roll inflation in both the scale-dependent bias of the large-scale structure (LSS) and mu-type distortion in the black-body spectrum of the cosmic microwave background (CMB). Read More

The bispectrum of the cosmic microwave background (CMB) generated by a correlation between a time-dependent gravitational potential and the weak gravitational lensing effect provides a direct measurement of the influence of dark energy on CMB. This bispectrum is also known to yield the most important contamination of the so-called "local-form" primordial bispectrum, which can be used to rule out all single-field inflation models. In this paper, we reexamine the effect of non-linear matter clustering on this bispectrum. Read More

We place new constraints on the contribution of blazars to the large-scale isotropic gamma-ray background (IGRB) by jointly analyzing the measured source count distribution (logN-logS) of blazars and the measured intensity and anisotropy of the IGRB. We find that these measurements point to a consistent scenario in which unresolved blazars make less than 20% of the IGRB intensity at 1-10 GeV while accounting for the majority of the measured anisotropy in that energy band. These results indicate that the remaining fraction of the IGRB intensity is made by a component with a low level of intrinsic anisotropy. Read More

Current observations suggest that the universe was reionized sometime before z~6. One way to observe this epoch of the universe is through the Near Infrared Background (NIRB), which contains information about galaxies which may be too faint to be observed individually. We calculate the angular power spectrum (C_l) of the NIRB fluctuations caused by the distribution of these galaxies. Read More

2011Jan
Affiliations: 1Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 2Dept. of Astronomy, Univ. of Texas, Austin

We reconsider the pixel-based, "template" polarized foreground removal method within the context of a next-generation, low-noise, low-resolution (0.5 degree FWHM) space-borne experiment measuring the cosmological B-mode polarization signal in the cosmic microwave background (CMB). This method was put forward by the Wilkinson Microwave Anisotropy Probe (WMAP) team and further studied by Efstathiou et al. Read More

While detection of the "local form" bispectrum of primordial perturbations would rule out all single-field inflation models, multi-field models would still be allowed. We show that multi-field models described by the $\delta N$ formalism obey an inequality between $f_{\rm NL}$ and one of the local-form {\it trispectrum} amplitudes, $\tau_{\rm NL}$, such that $\tau_{\rm NL}>\frac12(\frac65f_{\rm NL})^2$ with a possible logarithmic scale dependence, provided that 2-loop terms are small. Detection of a violation of this inequality would rule out most of multi-field models, challenging inflation as a mechanism for generating the primoridal perturbations. Read More

The last few years have seen a surge in excitement about measurements of statistics of the primordial fluctuations beyond the power spectrum. New ideas for precision tests of Gaussianity and statistical isotropy in the data are developing simultaneously with proposals for a wide range of new theoretical possibilities. From both the observations and theory, it has become clear that there is a huge discovery potential from upcoming measurements. Read More

The contribution of unresolved sources to the diffuse gamma-ray background could produce anisotropies in this emission on small angular scales. Recent studies have considered the angular power spectrum and other anisotropy metrics as tools for identifying contributions to diffuse emission from unresolved source classes, such as extragalactic and Galactic dark matter as well as various astrophysical gamma-ray source populations. We present preliminary results of an anisotropy analysis of the diffuse emission measured by the Fermi-LAT. Read More

We present a catalog of emission-line galaxies selected solely by their emission-line fluxes using a wide-field integral field spectrograph. This work is partially motivated as a pilot survey for the upcoming Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). We describe the observations, reductions, detections, redshift classifications, line fluxes, and counterpart information for 397 emission-line galaxies detected over 169 sq. Read More

2010Nov
Affiliations: 1Department of Astronomy, University of Texas at Austin, Austin, TX, 2Department of Astronomy, University of Texas at Austin, Austin, TX, 3Department of Astronomy, University of Texas at Austin, Austin, TX, 4Texas Cosmology Center, University of Texas at Austin, Austin, TX, 5Max Planck Institute for Extraterrestrial Physics, Garching, Germany, 6Department of Astronomy, University of Texas at Austin, Austin, TX, 7Max Planck Institute for Extraterrestrial Physics, Garching, Germany, 8Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA, 9George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A&M University, College Station, TX, 10Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 11Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA, 12Max Planck Institute for Extraterrestrial Physics, Garching, Germany, 13Department of Astronomy, University of Texas at Austin, Austin, TX, 14Max Planck Institute for Extraterrestrial Physics, Garching, Germany, 15Department of Astronomy, University of Texas at Austin, Austin, TX, 16McDonald Observatory, Austin, TX, 17Department of Astronomy, University of Texas at Austin, Austin, TX, 18Astrophysikalisches Institut Potsdam, Postdam, Germany, 19Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA, 20McDonald Observatory, Austin, TX

We study the escape of Ly-alpha photons from Ly-alpha emitting galaxies (LAEs) and the overall galaxy population using a sample of 99 LAEs at 1.9Read More

We calculate the effects of velocity-dependent dark matter annihilation cross sections on the intensity of the extragalactic gamma-ray background. Our formalism does not assume a locally thermal distribution of dark matter particles in phase space, and is valid for arbitrary velocity-dependent annihilation. As concrete examples, we calculate the effects of p-wave annihilation (with the $v$-weighted cross section of $\sigma v=a+bv^2$) on the mean intensity of extragalactic gamma rays produced in cosmological dark matter halos. Read More

2010Jul
Authors: Asantha Cooray, Steve Eales, Scott Chapman, David L. Clements, Olivier Dore, Duncan Farrah, Matt J. Jarvis, Manoj Kaplinghat, Mattia Negrello, Alessandro Melchiorri, Hiranya Peiris, Alexandra Pope, Mario G. Santos, Stephen Serjeant, Mark Thompson, Glenn White, Alexandre Amblard, Manda Banerji, Pier-Stefano Corasaniti, Sudeep Das, Francesco de_Bernardis, Gianfranco de_Zotti, Tommaso Giannantonio, Joaquin Gonzalez-Nuevo Gonzalez, Ali Ahmad Khostovan, Ketron Mitchell-Wynne, Paolo Serra, Yong-Seon Song, Joaquin Vieira, Lingyu Wang, Michael Zemcov, Filipe Abdalla, Jose Afonso, Nabila Aghanim, Paola Andreani, Itziar Aretxaga, Robbie Auld, Maarten Baes, Andrew Baker, Denis Barkats, R. Belen Barreiro, Nicola Bartolo, Elizabeth Barton, Sudhanshu Barway, Elia Stefano Battistelli, Carlton Baugh, Alexander Beelen, Karim Benabed, Andrew Blain, Joss Bland-Hawthorn, James~J. Bock, J. Richard Bond, Julian Borrill, Colin Borys, Alessandro Boselli, Francois R. Bouchet, Carrie Bridge, Fabrizio Brighenti, Veronique Buat, David Buote, Denis Burgarella, Robert Bussmann, Erminia Calabrese, Christopher Cantalupo, Raymond Carlberg, Carla Sofia Carvalho, Caitlin Casey, Antonio Cava, Jordi Cepa, Edward Chapin, Ranga Ram Chary, Xuelei Chen, Sergio Colafrancesco, Shaun Cole, Peter Coles, Alexander Conley, Luca Conversi, Jeff Cooke, Steven Crawford, Catherine Cress, Elisabete da Cunha, Gavin Dalton, Luigi Danese, Helmut Dannerbauer, Jonathan Davies, Paolo de Bernardis, Roland de Putter, Mark Devlin, Jose M. Diego, Herve Dole, Marian Douspis, Joanna Dunkley, James Dunlop, Loretta Dunne, Rolando Dunner, Simon Dye, George Efstathiou, Eiichi Egami, Taotao Fang, Patrizia Ferrero, Alberto Franceschini, Christopher C. Frazer, David Frayer, Carlos Frenk, Ken Ganga, Raphael Gavazzi, Jason Glenn, Yan Gong, Eduardo Gonzalez-Solares, Matt Griffin, Qi Guo, Mark Gurwell, Amir Hajian, Mark Halpern, Duncan Hanson, Martin Hardcastle, Evanthia Hatziminaoglou, Alan Heavens, Sebastien Heinis, Diego Herranz, Matt Hilton, Shirley Ho, Benne W. Holwerda, Rosalind Hopwood, Jonathan Horner, Kevin Huffenberger, David H. Hughes, John P. Hughes, Edo Ibar, Rob Ivison, Neal Jackson, Andrew Jaffe, Timothy Jenness, Gilles Joncas, Shahab Joudaki, Sugata Kaviraj, Sam Kim, Lindsay King, Theodore Kisner, Johan Knapen, Alexei Kniazev, Eiichiro Komatsu, Leon Koopmans, Chao-Lin Kuo, Cedric Lacey, Ofer Lahav, Anthony N. Lasenby, Andy Lawrence, Myung Gyoon Lee, Lerothodi L. Leeuw, Louis R. Levenson, Geraint Lewis, Nicola Loaring, Marcos Lopez-Caniego, Steve Maddox, Tobias Marriage, Gaelen Marsden, Enrique Martinez-Gonzalez, Silvia Masi, Sabino Matarrese, William G. Mathews, Shuji Matsuura, Richard McMahon, Yannick Mellier, Felipe Menanteau, Michal~J. Michalowski, Marius Millea, Bahram Mobasher, Subhanjoy Mohanty, Ludovic Montier, Kavilan Moodley, Gerald H. Moriarty-Schieven, Angela Mortier, Dipak Munshi, Eric Murphy, Kirpal Nandra, Paolo Natoli, Hien Nguyen, Seb Oliver, Alain Omont, Lyman Page, Mathew Page, Roberta Paladini, Stefania Pandolfi, Enzo Pascale, Guillaume Patanchon, John Peacock, Chris Pearson, Ismael Perez-Fournon, Pablo G. Perez-Gonz, Francesco Piacentini, Elena Pierpaoli, Michael Pohlen, Etienne Pointecouteau, Gianluca Polenta, Jason Rawlings, Erik~D. Reese, Emma Rigby, Giulia Rodighiero, Encarni Romero-Colmenero, Isaac Roseboom, Michael Rowan-Robinson, Miguel Sanchez-Portal, Fabian Schmidt, Michael Schneider, Bernhard Schulz, Douglas Scott, Chris Sedgwick, Neelima Sehgal, Nick Seymour, Blake~D. Sherwin, Jo Short, David Shupe, Jonathan Sievers, Ramin Skibba, Joseph Smidt, Anthony Smith, Daniel J. B. Smith, Matthew W. L. Smith, David Spergel, Suzanne Staggs, Jason Stevens, Eric Switzer, Toshinobu Takagi, Tsutomu Takeuchi, Pasquale Temi, Markos Trichas, Corrado Trigilio, Katherine Tugwell, Grazia Umana, William Vacca, Mattia Vaccari, Petri Vaisanen, Ivan Valtchanov, Kurt van der Heyden, Paul P. van der Werf, Eelco van_Kampen, Ludovic van_Waerbeke, Simona Vegetti, Marcella Veneziani, 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

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. Read More

In 2004, Creminelli and Zaldarriaga proposed a consistency relation for the primordial curvature perturbation of all single-field inflation models; it related the bispectrum in the squeezed limit to the spectral tilt. We have developed a technique, based in part on the Creminelli and Zaldarriaga argument, that can greatly simplify the calculation of the squeezed-limit bispectrum using the in-in formalism; we were able to arrive at a generic formula that does not rely on a slow-roll approximation. Using our formula, we explicitly tested the consistency relation for power-law inflation and for an exactly scale-invariant model by Starobinsky; for the latter model, Creminelli and Zaldarriaga's argument predicts a vanishing bispectrum whereas our quantum calculation shows a non-zero bispectrum that approaches zero in the long-wavelength limit and for inflation with a large number of e-folds. Read More

Since the first limit on the (local) primordial non-Gaussianity parameter, fNL, was obtained from COBE data in 2002, observations of the CMB have been playing a central role in constraining the amplitudes of various forms of non-Gaussianity in primordial fluctuations. The current 68% limit from the 7-year WMAP data is fNL=32+/-21, and the Planck satellite is expected to reduce the uncertainty by a factor of four in a few years from now. If fNL>>1 is found by Planck with high statistical significance, all single-field models of inflation would be ruled out. Read More

We study the evolution of linear density fluctuations of free-streaming massive neutrinos at redshift of z<1000, with an explicit justification on the use of a fluid approximation. We solve the collisionless Boltzmann equation in an Einstein de-Sitter (EdS) universe, truncating the Boltzmann hierarchy at lmax=1 and 2, and compare the resulting density contrast of neutrinos, \delta_{\nu}^{fluid}, with that of the exact solutions of the Boltzmann equation that we derive in this paper. Roughly speaking, the fluid approximation is accurate if neutrinos were already non-relativistic when the neutrino density fluctuation of a given wavenumber entered the horizon. Read More

2010Mar

To quantify how rare the bullet-cluster-like high-velocity merging systems are in the standard LCDM cosmology, we use a large-volume 27 (Gpc/h)^3 MICE simulation to calculate the distribution of infall velocities of subclusters around massive main clusters. The infall-velocity distribution is given at (1-3)R_{200} of the main cluster (where R_{200} is similar to the virial radius), and thus it gives the distribution of realistic initial velocities of subclusters just before collision. These velocities can be compared with the initial velocities used by the non-cosmological hydrodynamical simulations of 1E0657-56 in the literature. Read More

A long standing problem in weak lensing is about how to construct cosmic shear estimators from galaxy images. Conventional methods average over a single quantity per galaxy to estimate each shear component. We show that any such shear estimators must reduce to a highly nonlinear form when the galaxy image is described by three parameters (pure ellipse), even in the absence of the point spread function (PSF). Read More