Conveners
CMB, LSS and cosmological parameters: CMB + LSS
- Ruth Durrer
CMB, LSS and cosmological parameters: CMB + LSS
- Bronisław Rudak
CMB, LSS and cosmological parameters: CMB + LSS
- Tomasz Bulik
CMB, LSS and cosmological parameters: CMB
- Tomasz Bulik
CMB, LSS and cosmological parameters: LSS
- Marek Biesiada
CMB, LSS and cosmological parameters: CMB + LSS
- Marek Demiański
CMB, LSS and cosmological parameters: CMB + LSS
- Marek Demiański
CMB, LSS and cosmological parameters: CMB + LSS
- Bożena Czerny
Eric Linder
(UC Berkeley, United States)
08/09/2015, 14:00
Cosmic microwave background lensing has become a new cosmological probe, carrying rich information on the matter power spectrum and distances over the redshift range z≈1-4. We investigate the role of scale dependent new physics, such as from modified gravity, neutrino mass, and cold (low sound speed) dark energy, and its signature on CMB lensing. The distinction between different scale...
Laura Sagunski
(DESY, Germany)
08/09/2015, 14:20
We study soft limits of correlation functions for the density and velocity fields in
the theory of structure formation. First, we re-derive the (resummed) consistency conditions
at unequal times using the eikonal approximation. These are solely based on symmetry
arguments and are therefore universal. Then, we explore the existence of equal-time relations
in the soft limit which, on the other...
Patrick Breysse
(Johns Hopkins University, United States)
08/09/2015, 14:40
Intensity mapping is a promising new technique for studying the large-scale structure of the universe at redshifts inaccessible to traditional galaxy surveys. Intensity mapping studies typically focus on two-point statistics of a map such as the power spectrum. However, because these maps are highly non-Gaussian, there is a wealth of additional information which can be obtained by studying...
Vincenzo Salzano
(University of Szczecin, Poland)
08/09/2015, 15:00
We describe a new method to use Baryon Acoustic Oscillations to derive a constraint on the possible variation of the speed of light. The method relies on the fact that there is a simple relation between the angular diameter distance maximum and the Hubble function evaluated at the same maximum-condition redshift, which includes speed of light c. We evaluate if current or future missions can be...
Hu Zhan
(National Astronomical Observatories of China, China)
08/09/2015, 15:20
Non-parametric reconstruction is useful for constraining quantities that are potentially varying with time. A common practice is to replace the continuous function with an interpolation over a set of points or bins. This approach often involves many degrees of freedom, so that the constraints become too weak to be informative. In this presentation, we discuss priors that can help reduce the...
Jon Gudmundsson
(Stockholm University, Sweden)
08/09/2015, 16:10
SPIDER is a balloon-borne experiment designed to image the polarization of the cosmic microwave background with the aim of constraining models of the early universe. The experiment performed successfully during a 17 day flight in the 2014-2015 Antarctic season. During this first flight, SPIDER deployed a total of 2000 detectors, operating at 94 and 150 GHz, to map approximately 10% of the sky...
Moritz Munchmeyer
(Universite Pierre et Marie Curie, Institute Astrophysique de Paris, France)
08/09/2015, 16:30
Oscillating signatures in the correlation functions of the primordial density perturbations are predicted by a variety of inflationary models. A theoretical mechanism that has attracted much attention is a periodic shift symmetry as implemented in axion monodromy inflation. This symmetry leads to resonance non-gaussianities, whose key feature are logarithmically stretched oscillations....
Takashi Hiramatsu
(Kyoto University, Japan)
08/09/2015, 16:50
Cosmic Microwave Background (CMB) is known as a remnant of Big-Bang, and lots of past works in cosmology have paid attention to its potential to
prove the very early Universe. In these days, our main interests moved to quite fine structures of the Universe, for instance, the statistical properties of the
primordial fluctuations constructing the large-scale structure, and in fact we can...
Agnieska Cieplak
(Brookhaven National Laboratory, United States)
08/09/2015, 17:10
With the recent progress of Lyman-alpha forest power spectrum
measurements, understanding of the bias between the measured flux and
the underlying matter power spectrum is becoming crucial to the
percent level cosmological interpretation of these measurements.
Previous theoretical studies of this bias have used N-body and
hydro-PM simulations and inferred large-scale bias parameters that...
Alessio Notari
(Universitat de Barcelona, Spain)
08/09/2015, 17:30
I review several possible Anomalies for the Planck CMB data: the hemispherical power asymmetry, dipolar modulation and quadrupole-octupole alignments. I show that they are significantly affected by our proper motion. I also point out that the latter issue might be relevant also for the Calibration of the HFI instrument itself.
Caroline Heneka
(Dark Cosmology Centre, Denmark)
08/09/2015, 17:50
Clustering dark energy presents interesting phenomonology in comparison to standard homogeneous dark energy models. We investigate the impact of clustering dark energy on structure formation. Employing the spherical collapse formalism we obtain the collapse and virial density thresholds, as well as additional mass contributions due to non-linear dark energy perturbations. For an accurate...
Siri Chongchitnan
(University of Hull, United Kingdom)
09/09/2015, 09:00
Cosmic voids have been shown to be an effective probe of cosmology, complementary to galaxy clusters. But how reliable are the current theoretical models for void abundance?
In this talk, I will explain how the theory of "extreme cosmic voids" can be used as a consistency test for theories of void abundance. I will give a simple derivation of the size of the largest voids expected within a...
Tom Charnock
(University of Nottingham, United Kingdom)
09/09/2015, 09:20
There is a tension between measurements of the amplitude of the power spectrum of density perturbations inferred using the Cosmic Microwave Background (CMB) and directly measured by Large-Scale Structure (LSS) on smaller scales. We show that this tension exists, and is robust, for a range of LSS indicators including clusters, lensing and redshift space distortions and using CMB data. One...
Robert Crittenden
(Institute of Cosmology and Gravitation, United Kingdom)
09/09/2015, 09:40
We present a simple model for describing intrinsic correlations for galaxy sizes based on the halo model. Studying these correlations is important both to improve our understanding of galaxy properties and because it is an important potential systematic for weak lensing size magnification measurements. Our model assumes that the density field drives these intrinsic correlations and we also...
Giuseppe Fanizza
(Universita di Bari, Italy)
09/09/2015, 10:00
We present a new method to compute the deflection of light rays in a perturbed FLRW
geometry. By using the properties of the Geodesic Light Cone (GLC) gauge where null rays
propagate at constant angular coordinates irrespectively of the given (inhomogeneous and/or
anisotropic) geometry, the gravitational deflection of null geodesics can then be obtained
in any other gauge. This connection can...
Daniela Saadeh
(University College London, United Kingdom)
09/09/2015, 10:20
Large scales in the Cosmic Microwave Background (CMB) may break statistical isotropy. Bianchi models are often invoked as a possible explanation for these low-\ell features: they provide an anisotropic underlying pattern over which the usual stochastic fluctuations are superimposed. However, the Bianchi models generally employed in the analysis of CMB data — despite mimicking the anomalies in...
Christian Fidler
(CP3 , Belgium)
09/09/2015, 11:10
We discuss different gauge choices and their advantages in the context of N-body simulations. The initial conditions for N-body simulations are usually generated by employing the Zel'dovich approximation. We show that the initial displacements generated in this way generally receive a first-order relativistic correction.
We identify a novel gauge, called N-body gauge in the following, in which...
Mikhail Ivanov
(Ecole Polytechnique Federale de Lausanne, Switzerland)
09/09/2015, 11:10
The large scale structure of the Universe will become the leading observational probe in cosmology in the near future. However, the proper analysis of structure formation at small scales requires non-linear effects to be taken into account. Straightforward attempts to do so within perturbation theory faced several problems such as the appearance of non-physical infra-red (IR) enhancements from...
Alexander Eggemeier
(University of Sussex, United Kingdom)
09/09/2015, 11:30
Correlations in Fourier phases of the cosmological density field arise as a consequence of non-linear structure formation. Since two-point statistics are blind to phase factors, measures of pure phase information will not only be independent of the conventional power spectrum or two-point function, they also do not suffer from Gaussian variance on the modulus of the density field and linear...
Shohei Saga
(Nagoya University, Japan)
09/09/2015, 11:30
The standard cosmological perturbation theory is well established by by a number of observations such as the CMB anisotropy or the Large scales structure.
The standard cosmological perturbation theory includes three independent modes, i.e., scalar, vector, and tensor modes.
The scalar mode is the dominant component in our Universe and has been well determined by cosmological...
Florian Fuehrer
(Institut fuer Theoretische Physik, Germany)
09/09/2015, 11:50
In Growing Neutrino Quintessence strong backreaction effects, induced from large neutrino non-linearities, alter the cosmic history. I will present results obtained from N-body simulations which includes relativistic particles, non-linear scalar field equations and backreaction effects. Including the backreaction effects a realistic cosmology is hard to realize. This points to the need of...
Ignacy Sawicki
(University of Geneva, Switzerland)
09/09/2015, 11:50
There remains a slight but chronic tension between the latest Planck results and low-redshift observables: power seems to be consistently lacking at late times. I will describe how a simple model of dark energy, which has the same expansion history as LCDM, induces a scale-dependent correction to the growth rate of dark matter, suppressing power small scales. Since observations in the late...
Ichihiko Hashimoto
(Kyoto University, Japan)
09/09/2015, 12:10
Detection of primordial non-Gaussianity (PNG) is recognized as a powerful probe of cosmic inflation, and it can give an important clue for the generation mechanism of primordial density fluctuations. In this talk, we specifically consider the local-type PNG and discuss how well one can tightly constrain the higher-order non-Gaussianity parameters (gNL and tauNL) as well as the leading order...
Stefano Anselmi
(Case Western Reserve University, United States)
09/09/2015, 12:10
Cosmology has made fundamental progress thanks to the role of standard rulers. The acoustic peak in the Large Scale Structure clustering correlation function is one of them. However, in the era of precision cosmology, its power has been highly challenged by how late time non-linearities distort the correlation function. Fortunately this is not the end of the story! I will explain how we can...
Pierre Fleury
(IAP, France)
09/09/2015, 12:30
In standard cosmology, observations are interpreted as if light propagated through a universe whose inhomogeneities are modeled by perturbations with respect to the FLRW spacetime. However, the very narrow light beams associated with point-like sources—such as supernovae—probe the Universe at extremely small scales (~AU), up to which the perturbative approach should break down. In this talk, I...
Stefano Camera
(Jodrell Bank Centre for Astrophysics, United Kingdom)
10/09/2015, 14:00
Ultra-large cosmic scales supply a wealth of information most valuable for strengthening our knowledge of the Universe. For instance, they can teach us about the physical processes at play during the inflationary epoch, or enable us to either further confirm or rule out Einstein's theory of general relativity. This is because: on the one hand, there are relativistic corrections to the...
Julien Carron
(University of Sussex, United Kingdom)
10/09/2015, 14:20
During the nonlinear evolution from Gaussian initial conditions, Fourier modes of the cosmological matter density field gradually develop statistical dependence. A precise understanding of this cosmic (co)variance is essential for the ultimate success of the ambitious upcoming wide-field surveys targeting cosmic acceleration or modified theories of gravity. I will discuss the dynamics of the...
Toyokazu Sekiguchi
(University of Helsinki, Finland)
10/09/2015, 14:40
We consider decaying dark matter (DDM) as a resolution to the possible tension between cosmic microwave background (CMB) and weak lensing (WL) based determinations of the amplitude of matter fluctuations, $\sigma_8$. We perform N-body simulations in a model where dark matter decays into dark radiation and develop an accurate fitting formula for the non-linear matter power spectrum, which...
Alkistis Pourtsidou
(University of Portsmouth, United Kingdom)
10/09/2015, 15:00
21cm cosmology is a new and exciting area of research with
a great deal of potential. We have now entered an era of precision cosmology, but almost all of the information used to achieve this precision has come from the CMB at redshift z ~ 1100 or from galaxy surveys below z ~ 1.5. Using observations of the redshifted 21 cm line of atomic hydrogen (HI) we can look at previously unexplored...
Stephen Feeney
(Imperial College London, United Kingdom)
10/09/2015, 15:20
Recent results from the BICEP2, Keck Array and Planck collaborations demonstrate that Galactic foregrounds are an unavoidable obstacle in the search for evidence of inflationary gravitational waves in the cosmic microwave background (CMB) polarisation. Beyond the foregrounds, the effects of lensing by intervening large-scale structure further obscure all but the strongest inflationary signals...
Shuntaro Mizuno
(Waseda University, Japan)
10/09/2015, 16:10
We investigate the effect of equilateral-type primordial trispectrum on the halo/galaxy bispectrum.
We consider three types of equilateral primordial trispectra which are generated by quartic operators naturally appearing
in the effective field theory of inflation and can be characterized by three nonlinearity parameters,
$g_{\rm NL} ^{\dot{\sigma}^4}$, $g_{\rm NL} ^{\dot{\sigma}^2 (\partial...
Jinn-Ouk Gong
(Asia Pacific Center for Theoretical Physics, Republic of Korea)
10/09/2015, 16:30
We investigate the effects of homogeneous general dark energy on the non-linear matter perturbation in fully general relativistic context. The equation for the density contrast contains even at linear order new contributions which are non-zero for general dark energy. Taking into account the next-to-leading corrections, the total power spectrum with general dark energy deviates from the...
Pawel Bielewicz
(SISSA, Italy)
10/09/2015, 16:50
We present the first measurement of the correlation between the map of the CMB lensing potential derived from the Planck mission data and high-redshift galaxies detected by the Herschel-ATLAS (H-ATLAS) survey. This galaxy catalogue is the highest redshift sample for which the correlation between Planck CMB lensing and tracers of large-scale structure has been investigated so far. We perform a...
Matteo Tellarini
(ICG, Portsmouth, United Kingdom)
10/09/2015, 17:10
Primordial non-Gaussianity can lead to a scale-dependent bias in the density of collapsed halos relative to the underlying matter density. The galaxy power spectrum already provides constraints on local-type primordial non-Gaussianity complementary those from the cosmic microwave background (CMB), while the bispectrum contains additional shape information and has the potential to outperform...
Giovanni Marozzi
(Universite de Geneve, Switzerland)
10/09/2015, 17:30
In this talk, I will present the evaluation of the galaxy number counts to second order in cosmological perturbation theory in the Poisson gauge. The calculation is performed using an innovative approach based on the recently proposed ”geodesic light-cone” gauge, which allows us to determine the number counts in a purely geometric way. To conclude, I will present the numerical results for the...
Yuichiro Tada
(Kavli IPMU, Japan)
10/09/2015, 17:50
Primordial black holes (PBHs) are theoretical black holes which can be formed during the radiation dominant era through the gravitational collapse of radiational overdensities. It has been well known that in the context of the structure formation in our Universe such collapsed objects, e.g., halos/galaxies, could be considered as bias tracers of underlying matter fluctuations and the...
Cornelius Rampf
(Portsmouth University, United Kingdom)
11/09/2015, 14:00
Analytical methods have been fairly successful to understand the Newtonian regime of cosmological structure formation. Such methods are usually based on standard perturbation techniques which are however only approximative tools, and therefore might be not able to achieve the required accuracy to confront the theory with data from upcoming surveys. In this talk we show that it is actually...
Christian Reichardt
(University of Melbourne, Australia)
11/09/2015, 14:20
Measurements of the polarization of the cosmic microwave background (CMB) are rapidly becoming an important tool to test the standard model of cosmology. In particular, searches for the faint CMB B-mode signals offer the prospect of detecting inflationary gravitational waves on large angular scales and mapping out the large scale distribution of matter in the Universe through CMB lensing on...
Pawel Klimasara
(University of Silesia, Poland)
11/09/2015, 14:40
We discuss the recently proposed model where LSS of spacetime is parametrized by the usual real line R, while at small (QM) scales space is parametrized by real numbers from RM. Here RM is the real line in certain model M of formal Zermelo-Fraenkel set theory. When passing from RM to R the set-theoretic forcing on measure algebra of R3 has to be performed. The "old" set of reals RM is merely a...
Viraj Sanghai
(Queen Mary University of London, United Kingdom)
11/09/2015, 15:00
We construct a framework to probe the effect of non-linear structure formation on the large-scale expansion of the universe. We take a bottom-up approach to cosmological modelling by splitting up our universe into cells. The matter content within each cell is described by the post-Newtonian formalism. We assume that most of the cell is in the vicinity of weak gravitational fields, so that it...
Jacques Wagstaff
(Hamburg University, Germany)
11/09/2015, 15:20
We calculate the CMB spectral distortions due to the decay of causally generated magnetic fields at the electroweak and QCD phase transitions. We show that the decay of non-helical magnetic fields generated at either the electroweak or QCD scale produce μ and y-type distortions below 10^−8 which are probably not detectable by a future PIXIE-like experiment. We show that magnetic fields...
