4
4.0
Jun 29, 2018
06/18
by
Alexander Bonilla Rivera; Jairo Ernesto Castillo Hernandez
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eye 4
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We use Gamma Ray Bursts (GRBs) data from Y. Wang (2008) to put additional constraints on a set of cosmological dark energy models based on the holographic principle. GRBs are among the most complex and energetic astrophysical events known in the universe offering us the opportunity to obtain information from the history of cosmic expansion up to about redshift of $z\sim 6$. These astrophysical objects provide us a complementary observational test to determine the nature of dark energy by...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1601.00183
4
4.0
Jun 29, 2018
06/18
by
Francois Lanusse; Jean-Luc Starck; Adrienne Leonard; Sandrine Pires
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eye 4
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We propose a new mass-mapping algorithm, specifically designed to recover small-scale information from a combination of gravitational shear and flexion. Including flexion allows us to supplement the shear on small scales in order to increase the sensitivity to substructures and the overall resolution of the convergence map without relying on strong lensing constraints. In order to preserve all available small scale information, we avoid any binning of the irregularly sampled input shear and...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1603.01599
9
9.0
Jun 29, 2018
06/18
by
C. Sánchez; J. Clampitt; A. Kovacs; B. Jain; J. García-Bellido; S. Nadathur; D. Gruen; N. Hamaus; D. Huterer; P. Vielzeuf; A. Amara; C. Bonnett; J. DeRose; W. G. Hartley; M. Jarvis; O. Lahav; R. Miquel; E. Rozo; E. S. Rykoff; E. Sheldon; R. H. Wechsler; J. Zuntz; T. M. C. Abbott; F. B. Abdalla; J. Annis; A. Benoit-Lévy; G. M. Bernstein; R. A. Bernstein; E. Bertin; D. Brooks; E. Buckley-Geer; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; M. Crocce; C. E. Cunha; C. B. D'Andrea; L. N. da...
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eye 9
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Galaxies and their dark matter halos populate a complicated filamentary network around large, nearly empty regions known as cosmic voids. Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of $\sim50$ Mpc/$h$ or more that...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1605.03982
4
4.0
Jun 29, 2018
06/18
by
N. Gupta; A. Saro; J. J. Mohr; B. A. Benson; S. Bocquet; J. E. Carlstrom; R. Capasso; I. Chiu; T. M. Crawford; T. de Haan; J. P. Dietrich; C. Gangkofner; W. L. Holzapfel; M. McDonald; D. Rapetti; C. L. Reichardt
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eye 4
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We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the Meta-Catalog of X-ray detected Clusters of galaxies (MCXC; $\langle z \rangle = 0.14$) at South Pole Telescope (SPT) and Sydney University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150 and 220 GHz are extracted from the 2500 deg$^2$ SPT-SZ survey maps at the locations of SUMSS sources, producing a multi-frequency catalog of radio galaxies. In the direction of massive galaxy...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1605.05329
6
6.0
Jun 29, 2018
06/18
by
Stuart E. Harper; Clive Dickinson; Richard Battye; Lucas Olivari
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eye 6
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It has been proposed recently that the SKA1-MID could be used to conduct an HI intensity mapping survey that could rival upcoming Stage IV dark energy surveys. However, measuring the weak HI signal is expected to be very challenging due to contaminations such as residual Galactic emission, RFI, and instrumental 1/f noise. Modelling the effects of these contaminants on the cosmological HI signal requires numerical end-to-end simulations. Here we present how 1/f noise within the receiver can...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1606.09584
6
6.0
Jun 29, 2018
06/18
by
Philippe Brax; Patrick Valageas
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eye 6
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We consider K-mouflage models which are K-essence theories coupled to matter. We analyse their quantum properties and in particular the quantum corrections to the classical Lagrangian. We setup the renormalisation programme for these models and show that K-mouflage theories involve a recursive construction whereby each set of counter-terms introduces new divergent quantum contributions which in turn must be subtracted by new counter-terms. This tower of counter-terms can be constructed by...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1607.01129
4
4.0
Jun 29, 2018
06/18
by
S. Floerchinger; M. Garny; N. Tetradis; U. A. Wiedemann
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eye 4
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Treating dark matter at large scales as an effectively viscous fluid provides an improved framework for the calculation of the density and velocity power spectra compared to the standard assumption of an ideal pressureless fluid. We discuss how this framework can be made concrete through an appropriate coarse-graining procedure. We also review results that demonstrate that it improves the convergence of cosmological perturbation theory.
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1609.03466
4
4.0
Jun 29, 2018
06/18
by
Alkistis Pourtsidou
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eye 4
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We investigate the possibility of utilising 21cm intensity mapping, optical galaxy, and Cosmic Microwave Background (CMB) surveys to constrain the power spectrum of primordial fluctuations predicted by single-field slow-roll inflation models. Implementing a Fisher forecast analysis, we derive constraints on the spectral tilt parameter $n_{\rm s}$ and its first and second runnings $(\alpha_{\rm s},\beta_{\rm s})$. We show that 21cm intensity mapping surveys with instruments like the Square...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1612.05138
7
7.0
Jun 30, 2018
06/18
by
Xi-Bin Li; Hao-Feng Qin; Zhi-Song Zhang; Tong-Jie Zhang
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eye 7
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We study the Hubble parameter $H(z)$ in perturbed Friedmann universe and obtain an expression of the perturbed Hubble parameter $H(z,\textbf{n})$. We derive the Hubble parameter power spectrum by using the initial spectrum during inflation and the Bardeen transfer function. We obtain a semi-analytical expression in the case of cold dark matter (CDM) universe. Similar with luminosity distance, the Hubble parameter spectrum is suggested to be an useful observational tool to determine some...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1404.2168
5
5.0
Jun 30, 2018
06/18
by
Jens Chluba; Liang Dai; Donghui Jeong; Marc Kamionkowski; Amanda Yoho
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eye 5
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For the simplest inflation models, the recent detection of a large primordial B-mode polarization signal by the BICEP2 experiment indicates a slight tension with the upper limit on the tensor-to-scalar ratio, $r$, from the Planck satellite. Here, we discuss spatially varying $r$ as a possible explanation for this discrepancy. This idea seems attractive since it may also explain part of the hemispherical temperature power asymmetry seen by WMAP and Planck at large angular scales. If these two...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1404.2798
5
5.0
Jun 30, 2018
06/18
by
Kyungjin Ahn; Hao Xu; Michael L. Norman; Marcelo A. Alvarez; John H. Wise
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eye 5
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We present our prediction for the local 21 cm differential brightness temperature ($\delta T_{b}$) from a set of strongly clustered sources of Population III (Pop III) and II (Pop II) objects in the early Universe, by a numerical simulation of their formation and radiative feedback. These objects are located inside a highly biased environment, which is a rare, high-density peak ("Rarepeak") extending to $\sim7$ comoving Mpc. We study the impact of ultraviolet (UV) and X-ray photons on...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1405.2085
5
5.0
Jun 30, 2018
06/18
by
H. J. McCracken; M. Wolk; S. Colombi; M. Kilbinger; O. Ilbert; S. Peirani; J. Coupon; J. Dunlop; B. Milvang-Jensen; K. Caputi; H. Aussel; M. Béthermin; O. Le Fèvre
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eye 5
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We use percent-level precision photometric redshifts in the UltraVISTA-DR1 near-infrared survey to investigate the changing relationship be- tween galaxy stellar mass and the dark matter haloes hosting them to $z\sim2$. We achieve this by measuring the clustering properties and abundances of a series of volume-limited galaxy samples selected by stellar mass and star-formation activity. We interpret these results in the framework of a phenomenological halo model and numerical simulations. Our...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1411.4983
7
7.0
Jun 27, 2018
06/18
by
Martin Feix; Adi Nusser; Enzo Branchini
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eye 7
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Spatial variations in the distribution of galaxy luminosities, estimated from redshifts as distance proxies, are correlated with the peculiar velocity field. Comparing these variations with the peculiar velocities inferred from galaxy redshift surveys is a powerful test of gravity and dark energy theories on cosmological scales. Using ~ 2 $\times$ 10$^{5}$ galaxies from the SDSS Data Release 7, we perform this test in the framework of gravitational instability to estimate the normalized growth...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1503.05945
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12
Jun 27, 2018
06/18
by
Rahul Kothari; Shamik Ghosh; Pranati K. Rath; Gopal Kashyap; Pankaj Jain
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eye 12
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We consider an inhomogeneous model and independently an anisotropic model of primordial power spectrum in order to describe the observed hemispherical anisotropy in Cosmic Microwave Background Radiation. This anisotropy can be parametrized in terms of the dipole modulation model of the temperature field. Both the models lead to correlations between spherical harmonic coefficients corresponding to multipoles, l and l \pm 1. We obtain the model parameters by making a fit to TT correlations in...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1503.08997
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15
Jun 27, 2018
06/18
by
Alexander Eggemeier; Thorsten Battefeld; Robert E. Smith; Jens Niemeyer
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eye 15
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We propose an anisotropic generalisation of the line correlation function (ALCF) to separate and quantify phase information in the large-scale structure of galaxies. The line correlation function probes the strictly non-linear regime of structure formation and since phase information drops out of the power spectrum, the line correlation function provides a complementary tool to commonly used techniques based on two-point statistics. Furthermore, it is independent of linear bias as well as the...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1504.04036
4
4.0
Jun 30, 2018
06/18
by
T. Shanks; R. W. F. Johnson; J. A. Schewtschenko; J. R. Whitbourn
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eye 4
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The standard cosmological model, LCDM, provides an excellent fit to Cosmic Microwave Background (CMB) data. However, the model has well known problems. For example, the cosmological constant, is fine-tuned to 1 part in 10^100 and the cold dark matter (CDM) particle is not yet detected in the laboratory. Shanks previously investigated a model which assumed neither exotic particles nor a cosmological constant but instead postulated a low Hubble constant (H_0) to allow a baryon density compatible...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1402.5502
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5.0
Jun 30, 2018
06/18
by
Luis P. Chimento; Martín G. Richarte
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eye 5
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We investigate the interacting dark sector composed of dark matter, dark energy, and dark radiation for a spatially flat Friedmann-Robertson-Walker (FRW) background by introducing a three-dimensional internal space spanned by the interaction vector $\mathbf{Q}$ and solve the source equation for a linear transversal interaction. Then, we explore a realistic model with dark matter coupled to a scalar field plus a decoupled radiation term, analyze the amount of dark energy in the radiation era and...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1402.6371
6
6.0
Jun 30, 2018
06/18
by
Francisco-Shu Kitaura
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eye 6
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We report on new developments in the field of large-scale structure analysis. In particular, we present the KIGEN-approach, which allows for the first time for self-consistent phase-space reconstructions from galaxy redshift data.
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1405.6273
5
5.0
Jun 30, 2018
06/18
by
Richard Watkins; Hume A. Feldman
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eye 5
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The Cosmicflows-2 catalogue is a compendium of peculiar velocity measurements. While it has many objects in common with the COMPOSITE catalogue, a previously analysed collection of peculiar velocity data found to give an unexpectedly large bulk flow on large scales, the data in Cosmicflows-2 have been reanalysed to ensure consistency between distances measured using different methods. In particular, a focus on accurate distances led the authors of the Cosmicflows-2 to not correct for...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1407.6940
4
4.0
Jun 30, 2018
06/18
by
Adam J. Christopherson
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eye 4
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In this paper I review some recent, interlinked, work undertaken using cosmological perturbation theory -- a powerful technique for modelling inhomogeneities in the Universe. The common theme which underpins these pieces of work is the presence of non-adiabatic pressure, or entropy, perturbations. After a brief introduction covering the standard techniques of describing inhomogeneities in both Newtonian and relativistic cosmology, I discuss the generation of vorticity. As in classical fluid...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.4721
4
4.0
Jun 30, 2018
06/18
by
Anna Bonaldi; Michael L. Brown
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eye 4
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We apply the Correlated Component Analysis (CCA) method on simulated data of the Square Kilometre Array, with the aim of accurately cleaning the 21 cm reionization signal from diffuse foreground contamination. The CCA has been developed for the Cosmic Microwave Background, but the application of the Fourier-domain implementation of this method to the reionization signal is straightforward. The CCA is a parametric method to estimate the frequency behaviour of the foregrounds from the data by...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.5300
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6.0
Jun 30, 2018
06/18
by
Michelle Ntampaka; Hy Trac; Dougal J. Sutherland; Nicholas Battaglia; Barnabas Poczos; Jeff Schneider
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eye 6
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We present a modern machine learning approach for cluster dynamical mass measurements that is a factor of two improvement over using a conventional scaling relation. Different methods are tested against a mock cluster catalog constructed using halos with mass >= 10^14 Msolar/h from Multidark's publicly-available N-body MDPL halo catalog. In the conventional method, we use a standard M(sigma_v) power law scaling relation to infer cluster mass, M, from line-of-sight (LOS) galaxy velocity...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1410.0686
5
5.0
Jun 30, 2018
06/18
by
Robert R. Lindner; Paula Aguirre; Andrew J. Baker; J. Richard Bond; Devin Crichton; Mark J. Devlin; Thomas Essinger-Hileman; Patricio Gallardo; Megan B. Gralla; Matt Hilton; Adam D. Hincks; Kevin M. Huffenberger; John P. Hughes; Leopoldo Infante; Marcos Lima; Tobias A. Marriage; Felipe Menanteau; Michael D. Niemack; Lyman A. Page; Benjamin L. Schmitt; Neelima Sehgal; J. L. Sievers; Cristóbal Sifón; Suzanne T. Staggs; Daniel Swetz; Axel Weiß; Edward J. Wollack
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eye 5
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We present a multi-wavelength analysis of eleven Sunyaev Zel'dovich effect (SZE)-selected galaxy clusters (ten with new data) from the Atacama Cosmology Telescope (ACT) southern survey. We have obtained new imaging from the Large APEX Bolometer Camera (345GHz; LABOCA) on the Atacama Pathfinder EXperiment (APEX) telescope, the Australia Telescope Compact Array (2.1GHz; ATCA), and the Spectral and Photometric Imaging Receiver (250, 350, and $500\,\rm\mu m$; SPIRE) on the Herschel Space...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1411.7998
6
6.0
Jun 30, 2018
06/18
by
Dong Zhao; Ming-Hua Li; Ping Wang; Zhe Chang
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eye 6
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The influence of cosmological constant type dark energy in the early universe is investigated. This is accommodated by a new dispersion relation in de Sitter spacetime. We perform a global fitting to explore the cosmological parameters space by using the CosmoMC package with the recently released Planck TT and WMAP Polarization datasets. Using the results from global fitting, we compute a new CMB temperature-temperature spectrum. The obtained TT spectrum has lower power compared with the one...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1412.4965
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19
Jun 26, 2018
06/18
by
E. Grohs; G. M. Fuller; C. T. Kishimoto; M. W. Paris
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eye 19
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We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and cosmic microwave background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1502.02718
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11
Jun 27, 2018
06/18
by
Hélène Dupuy; Francis Bernardeau
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eye 11
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We propose a procedure to evaluate the impact of nonlinear couplings on the evolution of massive neutrino streams in the context of large-scale structure growth. Such streams can be described by general nonlinear conservation equations, derived from a multiple-flow perspective, which generalize the conservation equations of non-relativistic pressureless fluids. The relevance of the nonlinear couplings is quantified with the help of the eikonal approximation applied to the subhorizon limit of...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1503.05707
8
8.0
Jun 29, 2018
06/18
by
Stefano Gariazzo
texts
eye 8
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We perform a cosmological analysis in which we allow the primordial power spectrum of scalar perturbations to assume a shape that is different with respect to the usual power-law, arising from the simplest models of cosmological inflation. We parametrize the primordial power spectrum with a piecewise monotone cubic Hermite function and we use it to investigate how the constraints on the various cosmological parameters change: we find that the obtained limits are relaxed with respect to the...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1602.05902
5
5.0
Jun 29, 2018
06/18
by
Nithyanandan Thyagarajan; Aaron Parsons; David DeBoer; Judd Bowman; Aaron Ewall-Wice; Abraham Neben; Nipanjana Patra
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eye 5
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Unaccounted for systematics from foregrounds and instruments can severely limit the sensitivity of current experiments from detecting redshifted 21~cm signals from the Epoch of Reionization (EoR). Upcoming experiments are faced with a challenge to deliver more collecting area per antenna element without degrading the data with systematics. This paper and its companions show that dishes are viable for achieving this balance using the Hydrogen Epoch of Reionization Array (HERA) as an example....
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1603.08958
5
5.0
Jun 29, 2018
06/18
by
Clare Rumsey; Malak Olamaie; Yvette C. Perrott; Helen R. Russell; Farhan Feroz; Keith J. B. Grainge; Will J. Handley; Michael P. Hobson; Richard D. E. Saunders; Michel P. Schammel
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eye 5
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Using Arcminute Microkelvin Imager (AMI) SZ observations towards ten CLASH clusters we investigate the influence of cluster mergers on observational galaxy cluster studies. Although selected to be largely relaxed, there is disagreement in the literature on the dynamical states of CLASH sample members. We analyse our AMI data in a fully Bayesian way to produce estimated cluster parameters and consider the intrinsic correlations in our NFW/GNFW-based model. Varying pressure profile shape...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1604.06120
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14
Jun 28, 2018
06/18
by
A. Gruppuso; M. Gerbino; P. Natoli; L. Pagano; N. Mandolesi; D. Molinari
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eye 14
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The polarization of cosmic microwave background (CMB) can be used to constrain cosmological birefringence, the rotation of the linear polarization of CMB photons potentially induced by parity violating physics beyond the standard model. This effect produces non-null CMB cross correlations between temperature and B mode-polarization, and between E- and B-mode polarization. Both cross-correlations are otherwise null in the standard cosmological model. We use the recently released 2015 Planck...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1509.04157
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6.0
Jun 28, 2018
06/18
by
Keri L. Dixon; Ilian T. Iliev; Garrelt Mellema; Kyungjin Ahn; Paul R. Shapiro
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eye 6
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Observations of the epoch of reionization give us clues about the nature and evolution of the sources of ionizing photons, or early stars and galaxies. We present a new suite of structure formation and radiative transfer simulations from the PRACE4LOFAR project designed to investigate whether the mechanism of radiative feedback, or the suppression of star formation in ionized regions from UV radiation, can be inferred from these observations. Our source halo mass extends down to $10^8 M_\odot$,...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1512.03836
10
10.0
Jun 28, 2018
06/18
by
Xi Kang; Peng Wang
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eye 10
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The distribution of galaxies displays anisotropy on different scales and it is often referred as galaxy alignment. To understand the origin of galaxy alignments on small scales, one must investigate how galaxies were accreted in the early universe and quantify their primordial anisotropic at the time of accretion. In this paper we use N-body simulations to investigate the accretion of dark matter subhaloes, focusing on their alignment with the host halo shape and the orientation of mass...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1509.06804
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5.0
Jun 28, 2018
06/18
by
Thomas E. Collett; David J. Bacon
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eye 5
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Compound strong gravitational lensing is a rare phenomenon, but a handful of such lensed systems are likely to be discovered in forthcoming surveys. In this work, we use a double SIS lens model to analytically understand how the properties of the system impact image multiplicity for the final source. We find that up to six images of a background source can form, but only if the second lens is multiply imaged by the first and the Einstein radius of the second lens is comparable to, but does not...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1510.00242
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6.0
Jun 28, 2018
06/18
by
Vinicius Miranda; Wayne Hu; Chen He; Hayato Motohashi
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eye 6
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We develop methods to calculate the curvature power spectrum in models where features in the inflaton potential nonlinearly excite modes and generate high frequency features in the spectrum. The first nontrivial effect of excitations generating further excitations arises at third order in deviations from slow roll. If these further excitations are contemporaneous, the series can be resummed, showing the exponential sensitivity of the curvature spectrum to potential features. More generally,...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1510.07580
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6.0
Jun 28, 2018
06/18
by
Krishna Naidoo; Aurélien Benoit-Lévy; Ofer Lahav
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eye 6
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Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a > 3 sigma primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1512.02694
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4.0
Jun 30, 2018
06/18
by
R. S. Gonçalves; A. Bernui; R. F. L. Holanda; J. S. Alcaniz
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eye 4
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The cosmic distance-duality relation (CDDR), $d_L(z) (1 + z)^{2}/d_{A}(z) = \eta$, where $\eta = 1$ and $d_L(z)$ and $d_A(z)$ are, respectively, the luminosity and the angular diameter distances, holds as long as the number of photons is conserved and gravity is described by a metric theory. Testing such hypotheses is, therefore, an important task for both cosmology and fundamental physics. In this paper we use 91 measurements of the gas mass fraction of galaxy clusters recently reported by the...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1406.5618
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6.0
Jun 30, 2018
06/18
by
Ali Takey
texts
eye 6
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The dissertation has been published at the Potsdam University under the following URL: http://opus.kobv.de/ubp/volltexte/2014/7122/
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1407.6566
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5.0
Jun 30, 2018
06/18
by
Emma Chapman; Saleem Zaroubi; Filipe Abdalla; Fred Dulwich; Vibor Jelić; Benjamin Mort
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eye 5
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The removal of the Galactic and extragalactic foregrounds remains a major challenge for those wishing to make a detection of the Epoch of Reionization 21-cm signal. Multiple methods of modelling these foregrounds with varying levels of assumption have been trialled and shown promising recoveries on simulated data. Recently however there has been increased discussion of using the expected shape of the foregrounds in Fourier space to define an EoR window free of foreground contamination. By...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1408.4695
3
3.0
Jun 30, 2018
06/18
by
Shu-Lin Cheng; Wolung Lee; Kin-Wang Ng
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eye 3
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We discuss the generation of primordial magnetic fields during inflation in the dilaton-axion electromagnetism, in which the dilaton and axion dynamics are introduced in terms of two time dependent functions of the cosmic scale factor, $I(a) F^2/4$ and $J(a) F\tilde{F}/4$, respectively, where $F$ is the electromagnetic field strength and $\tilde{F}$ is its dual. We study the form of $J(a)$ that can generate a large seed magnetic field in the weak coupling regime, $I(a)
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.2656
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5.0
Jun 30, 2018
06/18
by
Jerod Caligiuri; Arthur Kosowsky; William H. Kinney; Naoki Seto
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eye 5
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A period of inflation in the early universe produces a nearly scale-invariant spectrum of gravitational waves over a huge range in wavelength. If the amplitude of this gravitational wave background is large enough to be detectable with microwave background polarization measurements, it will also be detectable directly with a space-based laser interferometer. Using a Monte Carlo sampling of inflation models, we demonstrate that the combination of these two measurements will strongly constrain...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.3195
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3.0
Jun 30, 2018
06/18
by
Richard A. Battye; Adam Moss; Jonathan A. Pearson
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eye 3
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We present current and future constraints on equations of state for dark sector perturbations. The equations of state considered are those corresponding to a generalized scalar field model and time-diffeomorphism invariant $L(g)$ theories that are equivalent to models of a relativistic elastic medium and also Lorentz violating massive gravity. We develop a theoretical understanding of the observable impact of these models. In order to constrain these models we use CMB temperature data from...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.4650
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3.0
Jun 30, 2018
06/18
by
Joyce Byun; Rachel Bean
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[Abridged] We consider how galaxy clustering data, from Mpc to Gpc scales, from upcoming large scale structure surveys, such as Euclid and DESI, can provide discriminating information about the bispectrum shape arising from a variety of inflationary scenarios. Through exploring in detail the weighting of shape properties in the calculation of the halo bias and halo mass function we show how they probe a broad range of configurations, beyond those in the squeezed limit, that can help distinguish...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.5440
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7.0
Jun 30, 2018
06/18
by
Shreya Arya; Geetanjali Sethi; Ojasvi Khare; Annu Malhotra
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In this paper we try to constrain the parameters of the Variable Chaplygin Gas Model, with equation of state $P=-A(a)/\rho$, where$A(a)$ is a positive function of the scale factor from lookback time measurements of high-z galaxies catalogued in the Gemini Deep Deep Survey(GDDS) and SNe Ia Union2.1\cite{union} Compilation provided by the Supernova Cosmology Project(SCP).
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1409.8521
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6.0
Jun 30, 2018
06/18
by
Abir Sarkar; Subinoy Das; Shiv K. Sethi
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We put constraints on the epoch of dark matter formation for a class of non-WIMP (Weakly Interacting Massive Particle) dark matter candidates. These models allow a fraction of Cold Dark Matter (CDM) to be formed between the epoch of Big Bang Nucleosynthesis (BBN) and the matter radiation equality. We show that for such models the matter power spectra might get strong suppression even on scales that could be probed by linear perturbation theory at low redshifts. Unlike the case of Warm Dark...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1410.7129
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4.0
Jun 30, 2018
06/18
by
Rhythm Shimakawa; Tadayuki Kodama; Charles C. Steidel; Ken-ichi Tadaki; Ichi Tanaka; Allison L. Strom; Masao Hayashi; Yusei Koyama; Tomoko L. Suzuki; Moegi Yamamoto
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In the redshift interval of $2
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1411.1408
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5.0
Jun 30, 2018
06/18
by
Julien Carron; Melody Wolk; István Szapudi
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We discuss an analytical approximation for the matter power spectrum covariance matrix and its inverse on translinear scales, $k \sim 0.1h - 0.8h/\textrm{Mpc}$ at $z = 0$. We proceed to give an analytical expression for the Fisher information matrix of the nonlinear density field spectrum, and derive implications for its cosmological information content. We find that the spectrum information is characterized by a pair of upper bounds, 'plateaux', caused by the trispectrum, and a 'knee' in the...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1412.5511
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27
Jun 26, 2018
06/18
by
Anastasia Fialkov; Rennan Barkana; Aviad Cohen
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The redshifted 21-cm background is expected to be a powerful probe of the early Universe, carrying both cosmological and astrophysical information from a wide range of redshifts. In particular, the power spectrum of fluctuations in the 21-cm brightness temperature is anisotropic due to the line-of-sight velocity gradient, which in principle allows for a simple extraction of this information in the limit of linear fluctuations. However, recent numerical studies suggest that the 21-cm signal is...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1502.02731
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14
Jun 27, 2018
06/18
by
Bin Chen; Ronald Kantowski
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The photometry profile of the integrated Sachs-Wolfe (ISW) effect recently obtained by the Planck consortium by stacking patches of Cosmic Microwave Background (CMB) sky maps around a large number of cosmic voids, contains a cold ring at about half the void's effective radius surrounded by a hot ring near the void's boundary. The source of the temperature structure is assumed to be the ISW effect but the exact cause of the ringed structure is not currently well understood, particularly the...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1504.03653
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4.0
Jun 30, 2018
06/18
by
D. Kleiner; K. A. Pimbblet; M. S. Owers; D. H. Jones; A. P. Stephenson
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A combination of $BRI$ photometry and archival Chandra X-ray data have been used to analyse the effects a minor merger has on the galaxy population of A1664. We utilise adaptive smoothing techniques in the 2D spatial distribution of cluster galaxies to reveal substructure $\sim$ 800 kpc South of the cluster core. We identify this substructure as most likely the remnant core of a merging group which has passed pericentre and responsible for triggering a cold front in the cluster core. We define...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1401.5065
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3.0
Jun 29, 2018
06/18
by
Meng-Zhen Lv; Jun-Qing Xia
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In this paper, we use the model dependent method to revisit the constraint on the well-known cosmic distance duality relation (CDDR). By using the latest SNIa samples, such as Union2.1, JLA and SNLS, we find that the SNIa data alone can not constrain the cosmic opacity parameter $\varepsilon$, which denotes the deviation from the CDDR, $d_{\rm L} = d_{\rm A}(1+z)^{2+\varepsilon}$, very well. The constraining power on $\varepsilon$ from the luminosity distance indicator provided by SNIa and GRB...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1606.08102
