Cosmological Parameter Estimation Using the Genus Amplitude-Application to Mock Galaxy Catalogs

Appleby, Stephen,Park, Changbom,Hong, Sungwook E.,Kim, Juhan American Astronomical Society 2018 The Astrophysical journal Vol.853 No.1

<P>We study the topology of the matter density field in two-dimensional slices and consider how we can use the amplitude A of the genus for cosmological parameter estimation. Using the latest Horizon Run 4 simulation data, we calculate the genus of the smoothed density field constructed from light cone mock galaxy catalogs. Information can be extracted from the amplitude of the genus by considering both its redshift evolution and magnitude. The constancy of the genus amplitude with redshift can be used as a standard population, from which we derive constraints on the equation of state of dark energy w(de)-by measuring A at z similar to 0.1 and z similar to 1, we can place an order Delta w(de) similar to O(15%) constraint on w(de). By comparing A to its Gaussian expectation value, we can potentially derive an additional stringent constraint on the matter density Delta Omega(mat) similar to 0.01. We discuss the primary sources of contamination associated with the two measurements-redshift space distortion (RSD) and shot noise. With accurate knowledge of galaxy bias, we can successfully remove the effect of RSD, and the combined effect of shot noise and nonlinear gravitational evolution is suppressed by smoothing over suitably large scales R-G >= 15 Mpc/h. Without knowledge of the bias, we discuss how joint measurements of the two-and three-dimensional genus can be used to constrain the growth factor beta = f/b. The method can be applied optimally to redshift slices of a galaxy distribution generated using the drop-off technique.</P>

Minkowski Tensors in Two Dimensions: Probing the Morphology and Isotropy of the Matter and Galaxy Density Fields

Appleby, Stephen,Chingangbam, Pravabati,Park, Changbom,Hong, Sungwook E.,Kim, Juhan,Ganesan, Vidhya American Astronomical Society 2018 The Astrophysical journal Vol.858 No.2

Direct search for features in the primordial bispectrum

Appleby, S.,Gong, J.O.,Hazra, D.K.,Shafieloo, A.,Sypsas, S. North-Holland Pub. Co 2016 Physics letters. Section B Vol.760 No.-

We study features in the bispectrum of the primordial curvature perturbation correlated with the reconstructed primordial power spectrum from the observed cosmic microwave background temperature data. We first show how the bispectrum can be completely specified in terms of the power spectrum and its first two derivatives, valid for any configuration of interest. Then using a model-independent reconstruction of the primordial power spectrum from the Planck angular power spectrum of temperature anisotropies, we compute the bispectrum in different triangular configurations. We find that in the squeezed limit at k~0.06 Mpc<SUP>-1</SUP> and k~0.014 Mpc<SUP>-1</SUP> there are marginal 2σ deviations from the standard featureless bispectrum, which meanwhile is consistent with the reconstructed bispectrum in the equilateral configuration.

Topology of Large-scale Structures of Galaxies in Two Dimensions-Systematic Effects

Appleby, Stephen,Park, Changbom,Hong, Sungwook E.,Kim, Juhan American Astronomical Society 2017 The Astrophysical journal Vol.836 No.1

<P>We study the two-dimensional topology of galactic distribution when projected onto two-dimensional spherical shells. Using the latest Horizon Run 4 simulation data, we construct the genus of the two-dimensional field and consider how this statistic is affected by late-time nonlinear effects-principally gravitational collapse and redshift space distortion (RSD). We also consider systematic and numerical artifacts, such as shot noise, galaxy bias, and finite pixel effects. We model the systematics using a Hermite polynomial expansion and perform a comprehensive analysis of known effects on the two-dimensional genus, with a view toward using the statistic for cosmological parameter estimation. We find that the finite pixel effect is dominated by an amplitude drop and can be made less than 1% by adopting pixels smaller than 1/3 of the angular smoothing length. Nonlinear gravitational evolution introduces time-dependent coefficients of the zeroth, first, and second Hermite polynomials, but the genus amplitude changes by less than 1% between z = 1 and z = 0 for smoothing scales R-G > 9 Mpc/h. Non-zero terms are measured up to third order in the Hermite polynomial expansion when studying RSD. Differences in the shapes of the genus curves in real and redshift space are small when we adopt thick redshift shells, but the amplitude change remains a significant similar to O(10%) effect. The combined effects of galaxy biasing and shot noise produce systematic effects up to the second Hermite polynomial. It is shown that, when sampling, the use of galaxy mass cuts significantly reduces the effect of shot noise relative to random sampling.</P>

Minkowski Tensors in Three Dimensions: Probing the Anisotropy Generated by Redshift Space Distortion

Appleby, Stephen,Chingangbam, Pravabati,Park, Changbom,Yogendran, K. P.,Joby, P. K. American Astronomical Society 2018 The Astrophysical journal Vol.863 No.2

PROBING BULK FLOW WITH NEARBY SNe Ia DATA

Appleby, Stephen,Shafieloo, Arman,Johnson, Andrew IOP Publishing 2015 The Astrophysical journal Vol.801 No.2

<P>We test the isotropy of the local universe using low-redshift supernova data from various catalogs and the nonparametric method of smoothed residuals. Using a recently developed catalog that combines supernova data from various surveys, we show that the isotropic hypothesis of a universe with zero velocity perturbation can be rejected with moderate significance, with p-value similar to 0.07 out to redshift z < 0.045. We estimate the direction of maximal anisotropy on the sky for various preexisting catalogs and show that it remains relatively unaffected by the light-curve fitting procedure. However, the recovered direction is biased by the underlying distribution of data points on the sky. We estimate both the uncertainty and bias in the direction by creating mock data containing a randomly oriented bulk flow and using our method to reconstruct its direction. After correcting for this bias effect, we infer the direction of maximum anisotropy as (b, l) = (20 degrees, 276 degrees) +/- (12 degrees, 29 degrees) in galactic coordinates. Finally, we compare the anisotropic signal in the data to mock realizations in which large-scale velocity perturbations are consistently accounted for at the level of linear perturbation theory. We show that including the effect of the velocity perturbation in our mock catalogs degrades the significance of the anisotropy considerably, with p-value increasing to similar to 0.29. One can conclude from our analysis that there is a moderate deviation from isotropy in the supernova data, but the signal is consistent with a large-scale bulk velocity expected within Lambda CDM.</P>

LTP in hippocampal neurons is associated with a CaMKII‐mediated increase in GluA1 surface expression

Appleby, Vanessa J.,Corrê,a, Sonia A. L.,Duckworth, Joshua K.,Nash, Joanne E.,Noë,l, Jacques,Fitzjohn, Stephen M.,Collingridge, Graham L.,Molná,r, Elek Blackwell Publishing Ltd 2011 Journal of Neurochemistry Vol.116 No.4

<P> <I>J. Neurochem.</I> (2011) <B>116</B>, 530–543.</P><P><B>Abstract</B></P><P>The use of hippocampal dissociated neuronal cultures has enabled the study of molecular changes in endogenous native proteins associated with long‐term potentiation. Using immunofluorescence labelling of the active (Thr286‐phosphorylated) alpha‐Ca<SUP>2+</SUP>/calmodulin‐dependent protein kinase II (CaMKII) we found that CaMKII activity was increased by transient (3 × 1 s) depolarisation in 18‐ to 21‐day‐old cultures but not in 9‐ to 11‐day‐old cultures. The increase in Thr286 phosphorylation of CaMKII required the activation of NMDA receptors and was greatly attenuated by the CaMKII inhibitor KN‐62. We compared the effects of transient depolarisation on the surface expression of GluA1 and GluA2 subunits of the alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionate receptor and found a preferential recruitment of the GluA1 subunit. CaMKII inhibition prevented this NMDA receptor‐dependent delivery of GluA1 to the cell surface. CaMKII activation is therefore an important factor in the activity‐dependent recruitment of native GluA1 subunit‐containing alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionate receptors to the cell surface of hippocampal neurons.</P>

Using the Topology of Large Scale Structure for Cosmological Parameter Estimation

Stephen Appleby 한국천문학회 2018 天文學會報 Vol.43 No.2

Lithium borate glass ceramics as thermal neutron imaging plates

G.A. Appleby,C.M. Bartle,G.V.M. Williams,A. Edgar 한국물리학회 2006 Current Applied Physics Vol.6 No.3

A new glass ceramic composed of a lithium borate glass matrix containing Eu-doped BaCl2 crystals has been developed for thermalneutron radiography, and has been tested for sensitivity toc-radiation. It is shown to exhibit photostimulated luminescence (PSL) uponX- and c-irradiation. The PSL arises from orthorhombic BaCl2 nanocrystallites in the glass ceramics, which also contain a PSL-inactivephase of cubic BaCl2. The relative PSL eciency of the glass ceramics has a strong dependence on gamma energy, which correlates withrelative half-thickness. The eect of uoride doping in the glass ceramics has been found to substantially increase the PSL, which rangesfrom. 0.6% without uoride doping to. 8% with 0.2 F:Cl concentration, all relative to Fujilm’s commercial neutron imaging plateBAS-ND.

Cosmology and fundamental physics with the Euclid satellite

Amendola, Luca,Appleby, Stephen,Avgoustidis, Anastasios,Bacon, David,Baker, Tessa,Baldi, Marco,Bartolo, Nicola,Blanchard, Alain,Bonvin, Camille,Borgani, Stefano,Branchini, Enzo,Burrage, Clare,Camera, Springer International Publishing 2018 Living reviews in relativity Vol.21 No.1

<P>Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015–2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. Although the main driver for Euclid is the nature of dark energy, Euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. In this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. We discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. This review has been planned and carried out within Euclid’s Theory Working Group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the Euclid mission.</P>