Talks Schedule of "Theoretical and Observational Progress on the Large-scale Structure of the Universe"

Venue: Headquarters of the European Southern Observatory (ESO), Auditorium "Eridanus"

Dates: July 20 - 24, 2015

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 MondayTuesday WednesdayThursday Friday
08:30 - 09:00 Morning CoffeeMorning Coffee Morning CoffeeMorning Coffee Morning Coffee
09:00 - 09:25 Welcome Alexie LeauthaudUnderstanding the galaxy-halo connection for massive galaxies from the BOSS survey at z=0.5
There is a tremendous interest in constraining the size, stellar mass, and halo mass evolution of the very most massive galaxies in the universe. With the final DR12 data release, the BOSS survey has collected spectra for 700,000 massive galaxies (M*>10^11) at z~0.5. covering a tremendous volume of 10.6 Gpc^3 providing the potential to study the most massive galaxy populations with vanishing sample variance. However, the sample selections of BAO surveys involved complex color cuts which are not necessarily optimized for galaxy science. As a result, the selection function and stellar mass completeness of these samples often remain poorly understood. I will describe efforts to characterize the BOSS mass completeness and to model the BOSS galaxy population using abundance matching and age matching techniques. I will show how these models compare with measurements of BOSS correlation functions and galaxy-galaxy lensing.
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09:00 - 09:25 Uros SeljakAnalytic approaches to large scale structure: perturbation theory and beyond
I will review analytic approaches to large scale structure, which start with perturbation theory on large scales, supplemented with methods to include non-perturbative effects on small scales. The latter is often done using the halo model. I will present some applications of this approach, including dark matter clustering and galaxy clustering in redshift space, emphasizing successes and challenges of these approaches.
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Joop SchayeInsights from cosmological hydrodynamical simulations
I will compare cosmological hydrodynamical simulations from the OWLS, Cosmo-OWLS and EAGLE projects to observations of the distribution of matter. The simulations will be used to investigate whether the re-distribution of baryons by feedback processes associated with galaxy formation may be important for observational cosmology.
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09:00 - 09:25 Antony LewisCMB lensing with Planck
I'll review the Planck 2015 CMB lensing results, discuss constraints on cosmological parameters and consistency with other data, and briefly mention open issues and future directions.
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09:25 - 09:50 John PeacockOpening Review
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Hiranya PeirisFrom precision to accuracy: Cosmology with large imaging surveys
Photometric surveys are often larger and extend to fainter magnitudes than spectroscopic samples, and can therefore yield more precise cosmological measurements. However, photometric data are significantly contaminated by multiple sources of systematics, either intrinsic, observational, or instrumental. These systematics affect the properties of the raw images in complex ways, propagate into the final catalogues, and create spurious spatial correlations. Some of these correlations may also be imprinted in spectroscopic catalogues, since the latter rely on targets selected from imaging data. Therefore, not just precise - but also accurate - cosmological inferences from imaging surveys require careful mitigation of spatially-varying systematics. I will present a new framework of extended mode projection to robustly mitigate the impact of such systematics on power spectrum measurements. I will demonstrate the effectiveness of the technique, showing constraints on primordial non-Gaussianity using the clustering of 800,000 photometric quasars from the Sloan Digital Sky Survey in the redshift range 0.5 < z < 3.5. Finally, I will present a framework to map the observing conditions of the Science Verification data in the Dark Energy Survey (DES) and incorporate them into end-to-end simulations of the DES transfer function. The considerations presented here are relevant to all multi-epoch surveys, and will be essential for exploiting future high-cadence surveys such as the Large Synoptic Survey Telescope (LSST), which will require detailed null-tests and realistic end-to-end image simulations for correct cosmological inferences.
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09:25 - 09:50 Ravi ShethRecent progress in understanding halo and void abundances and clustering
I will discuss recent developments in our understanding of halo bias, emphasizing the connection between large scale bias and small scale halo formation, before discussing how these translate to using voids as cosmological probes as well.
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Debora SijackiThe Illustris simulation: a new look at galaxy - black hole co-evolution
Hydrodynamical cosmological simulations are one of the most powerful tools to study the formation and evolution of galaxies in the fully non-linear regime. I will discuss which feedback mechanisms are needed to reproduce realistic stellar masses and galaxy morphologies in the present day Universe and argue that the black hole feedback is necessary for the quenching of massive galaxies. I will then present the global properties of galaxies and their central black holes as obtained with the novel cosmological simulation Illustris. I will demonstrate how black hole - host galaxy scaling relations depend on galaxy morphology and colour, highlighting the implications for the co-evolutionary picture between galaxies and their central black holes.
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09:25 - 09:50 Benjamin JoachimiProgress and challenges in large-scale structure weak lensing
Weak gravitational lensing is now a well-established probe of the large-scale matter distribution, providing competitive constraints on cosmological models and structure formation. I will highlight recent results, focusing on the KiDS and RCSLenS surveys. Based on the experience with these datasets and recent theoretical progress, I will discuss the major challenges in the observations, the modelling, and the analysis methodology, of weak lensing, which will need to be overcome in time for the next generation of LSS cosmology surveys like LSST and Euclid.
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09:50 - 10:15 Benjamin WandeltPlanck 2015 results
The cosmic microwave background anisotropies probe the large scale structure of the universe both directly and indirectly. The physical information inferred from the Planck temperature and polarization maps are a cornerstone of the emerging standard cosmological model. I will present some highlights of the Planck 2015 results discussing their impact on as wide-ranging questions such as the primordial origin of structure, the physics of photon decoupling, the physics of neutrinos, dark matter, and the current acceleration epoch.
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Anze SlosarLyman-alpha forest: the past, the future
I will discuss recent results in hand and future promises about using the Lyman-alpha forest as a cosmological probe.
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09:50 - 10:15 Leonardo SenatoreRecent Developments from the Effective Field Theory of Large Scale Structures
The Effective Field Theory of Large Scale Structures is a novel research program that aims at developing a systematic understanding of large scale structures at long distances by expanding in the smallness of the long wavelength perturbations. I will present the most recent results and developments.
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Tiziana Di MatteoThe next frontier of high-redshift quasars and massive galaxies
I will discuss predictions for the first quasars and the first galaxies and their contribution to reionization from the BlueTides simulation. BlueTides is a uniquely large volume and high resolution simulation to study the high redshift universe: with 0.7 trillion particles in a volume of 1/2 of a gigaparsec on the side. This is the first simulation large enough to resolve the relevant scales, that the first massive galaxies and quasar form. These massive objects at high redshifts will be the next frontier for the next generation telescopes (EUCLID, WFIRST and ALMA).
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09:50 - 10:15 Eduardo RozoCluster Cosmology in the Post-Planck Era
I will review the status of cosmology with galaxy clusters today, placing particular emphasis on the agreement/tension with Planck CMB primaries, and discuss prospects for improvement in the near future.
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10:15 - 10:40 Shirley HoHow to learn to love the BOSS
Baryon Oscillations Spectroscopic Survey have just finished surveying 10,000 square degrees, containing over 1 million galaxies within the redshift range of 0.2 < z < 0.7. I will discuss some of the most recent results from BOSS and other surveys including the 1% measurement of BAO at z=0.57 from BOSS and constraints on gravity using all of the currently available redshift space distortions measurements from BOSS and other surveys. I will also introduce new probes from large scale structure which will help us learn more about gravity and galaxy environment. I will finally put all of this into the context of current and upcoming surveys including Sloan Digital Sky Survey 4, Dark Energy Spectroscopic Instrument, Large Synoptic Survey Telescope and WFIRST-AFTA.
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Matteo VielPerspectives of discoveries from intergalactic space
I will review recent constraints on neutrino masses and cold dark matter coldness by using Lyman-alpha forest data. Moreover, I will present recent results on the cross-correlation analysis from LSS probe and the diffuse intergalactic background as measured by Fermi/LAT.
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10:15 - 10:40 Francis BernardeauLarge-deviation functions in the large-scale structure of the universe
The existence of large deviation functions (LDF) is ubiquitous in many fields of applied mathematics and statistical mechanics such as basic random processes, equilibrium many body systems or even nonequilibrium, disordered and chaotic systems. I present here results that show that such large deviation functions can be built in the context of the evolution of the large-scale structure of the universe. The presentation will introduce the two key relations the LDF obey and give example on how such relations can be exploited such as the reconstruction of the density probability distribution functions or density profiles.
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Risa WechslerSimulating large cosmological surveys
TBA
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10:15 - 10:40 Nick BattagliaThe role of galaxy cluster simulations in the current cosmological paradigm
The use of galaxy clusters as a precision cosmological probe is currently systematics limited. I will review these systematic uncertainties and how simulations combined with observations are beginning to address them.
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10:40 - 11:10BreakBreak 10:40 - 11:10BreakBreak 10:40 - 11:10Break
11:10 - 11:35 Ariel SanchezCosmological implications of anisotropic galaxy clustering measurements in BOSS
The large-scale distribution of galaxies offers a powerful probe of the expansion history of the Universe and the growth rate of cosmic structures. This information can be used to distinguish between the dark energy and modified gravity scenarios for the origin of cosmic acceleration. In this talk, I describe our current theoretical understanding the full shape of anisotropic galaxy clustering measurements. I also review the cosmological implications of the latest galaxy clustering measurements from the Baryon Oscillation Spectroscopic Survey (BOSS).
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Chris BlakeDark Energy Down Under: testing cosmological physics with redshifts and velocities
The apparent existence of "dark energy" points to a failure in our physical understanding of the Universe. Large surveys of galaxies can help address this mystery by mapping out both cosmic expansion and gravitational physics using a variety of geometrical and dynamical techniques. In this talk I will review recent tests of the cosmological model using density-field and velocity-field information from the WiggleZ Dark Energy Survey and 6-degree Field Galaxy Survey. I will also discuss prospects for the Taipan Survey, a new low-redshift cosmological survey starting next year.
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11:10 - 11:35 Camille BonvinRelativistic effects in large-scale structure surveys
The distribution of galaxies, as well as their observed shape and size provide a powerful way to probe dark energy and modified gravity models. In order to exploit these observables properly it is necessary to understand what we are really measuring when we look at the distribution, sizes and shapes of galaxies. Since our universe is not completely homogeneous and isotropic, we only see a distorted picture of our sky. In this talk, I will discuss the various relativistic effects that distort our observations. I will show that even though these effects complicate the interpretation of galaxy surveys, they are very useful since they contain information on the dynamic of the universe and can therefore be regarded as a new opportunity for future surveys.
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Kazuya KoyamaNon-linear structure formation in modified gravity models
The discovery of the accelerated expansion of the Universe has come relatively late in our study of the cosmos, but it has opened up many new questions about the nature of gravity and what the Universe might contain. Is the acceleration being driven by dark energy? Or is generalrelativity (GR) itself in error, requiring a modification at large scales to account for the late acceleration? Structure formation in our Universe can be different even if the geometry of the homogeneous and isotropic universeis the same in these two classes of models, offering a possibility to distinguish between them observationally. Non-linear structure formation is complicatedby the fifth force that commonly appears in modified gravity models and new techniques are required to analyse it. We will discuss novel methods to test GRon cosmological scales, building on the recent developments of N-body simulations for modified gravity.
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11:10 - 11:27 Tommaso GiannantonioCMB Lensing Tomography with the Dark Energy Survey Science Verification galaxies
I present the measurement of the cross-correlation between galaxies from the Dark Energy Survey (DES) Science Verification data and the lensing of the CMB as reconstructed by Planck and the South Pole Telescope. By measuring the cross-correlations in five redshift bins, and combining them with the DES galaxy auto-correlations, I demonstrate how these data can be used to constrain the growth of structure across cosmic time.
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11:35 - 12:00 Hector Gil-MarinMeasuring the galaxy bias, gravity and sigma8 using the bispectrum technique
Observations of Type Ia supernovae suggest that the Universe has been accelerating since redshift z ~ 0.5. Today the physical mechanism responsible for this process is still a mystery. The simplest model to explain the acceleration of the Universe is the LCDM model. This model assumes that the acceleration is driven by an exotic form of energy with negative pressure that might be related to the vacuum energy of quantum field theories. This theory is equivalent to adding an integration constant to the Einstein equations. Alternative theories to the vacuum energy, such as f(R) class of models propose a modification of gravity in the infrared that would produce an accelerated expansion. These models produceaccelerated expansion through a modification of the Einstein-Hilbert action by an arbitrary function of the Ricci scalar R. As a consequence, an extra propagating scalar field appears that mediates a fifth force on all forms of matter. In case the expansion of the Universe is driven by some of these alternative models, we expect that the growth of structure, namely f, to be different to the predictions from General Relativity. In order to detect such potential deviations in the growth of structure of the Universe, the redshift space power spectrum multipoles have been measured from galaxy spectroscopic surveys such as BOSS. One of the caveats of this technique is that at large scales the growth factor is fully degenerate with the amplitude of the linear dark matter power spectrum, and therefore only the quantity sigma8 times f can be constrained. Measuring the bispectrum allows to break this degeneracy, and therefore to obtain an isolated measurement of the growth of structure (and also sigma8) from galaxy surveys.However, measuring the bispectrum from galaxy surveys and more importantly modelling its behaviour in redshift space for biased objects present several challenges that must be addressed if one wants to use this technique. The aim of this talk is to talk about these challenges and limitations and present some possible solutions, focusing in the applicability of the method to galaxy surveys, with especial attention to BOSS.
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Ben GranettThe VIPERS view of large-scale structure at redshift 1
The VIMOS Public Extragalactic Redshift Survey (VIPERS) is an ESO large program targeting 100k galaxies with spectroscopy at redshifts z=0.5 to 1.2. With complementary photometric coverage from UV to IR and morphological measures from CFHTLS, this unique dataset is providing unprecedented detail on the properties of galaxies and the growth of structure at redshift 1. We present the first view of the cosmic structures mapped over the complete survey volume and review the initial cosmological results. VIPERS provides the first measurement of the galaxy power spectrum at redshift 1 giving constraints on the matter and baryon densities with precision matching that of low-redshift surveys. In redshift space, the clustering of galaxies provides key constraints on the growth rate of structure and the nature of gravity on large scales. With VIPERS we investigate the growth rate at z=0.8 measured from the correlation function and power spectrum as a function of galaxy type. Since galaxies are biased tracers of the underlying field, comparing subsamples provides a means to uncover modelling systematics due to the non-linear dynamics. Furthermore by considering the covariance between subsamples we may optimise the measurement. Beyond the 1 and 2 point statistics, the high sampling rate of VIPERS allows us to probe the distribution of cosmic voids. The anisotropic void-galaxy correlation measured in VIPERS provides an additional novel test of gravity.
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11:35 - 12:00 Donghui JeongClustering fossils in the LSS of the Universe
I will describe a generic mechanism, called clustering fossils, of detecting the amplitude of primordial spectator fields that generated spectator-scalar-scalar bispectrum at early times.
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Ewald PuchweinSimulating cosmic structure formation in modified gravity
Modified gravity could provide an alternative explanation of the accelerated expansion of the Universe, while at the same time affecting cosmic structure growth on smaller scales. Cosmological simulations that include modified gravity models are needed to make detailed predictions in the non-linear regime, as well as to find the most promising observational signatures of such theories. We will present both collisionless and hydrodynamical simulations of a promising modified gravity model, i.e. chameleon-f(R) gravity, and discuss how such a modification of gravity can be constrained or detected. Furthermore, we highlight degeneracies between modified gravity effects and uncertain baryonic physics effects and point out how simulations can help to break these degeneracies.
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11:27 - 11:44 Anthony PullenConstraining Gravity at the Largest Scales through CMB Lensing and Galaxy Velocities
We discuss recent work exploring the use of CMB lensing to probe E_G, the ratio between curvature and velocity perturbations. This quantity is distinct for various gravity models, breaking the degeneracy in current cosmological probes of gravity and dark energy. While the lensing signal within E_G has traditionally been probed with galaxy-galaxy lensing, galaxy-CMB lensing is a more robust lensing tracer that can probe E_G at higher redshifts with fewer astrophysical uncertainties. We present competitive constraints to E_G using CMB data from Planck and galaxy data from the SDSS BOSS survey, which are consistent with general relativity (GR). We also show forecasts for future surveys, finding that upcoming photometric surveys combined with next-generation CMB surveys like Advanced ACTPol could produce <1%-level constraints that could potentially rule out alternatives to GR.
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12:00 - 12:25 Francisco KitauraModelling and inferring the Cosmological Large Scale Structure
Upcoming surveys will require an accurate modelling of the clustering statistics to robustly infer the cosmological parameters and constrain dark energy. I present an efficient approach based on perturbation theory and galaxy bias, including nonlinear, nonlocal, and stochastic contributions, calibrated on N-body simulations. This method has been applied to the BOSS DR12 survey producing more than 12000 mock galaxy catalogs fitting the 2 and 3 point correlation functions and the quadrupole.Moreover, I present two novel inference techniques, and discuss applications of these techniques for future surveys like JPAS, eBOSS, Euclid, and 4MOST.
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Guilhem LavauxNew methods in the analysis of galaxy distance catalogues
New distance surveys, from which peculiar velocities can be inferred, have emerged in the recent years like SFI++, 6dFv, CosmicFlows-1, CosmicFlows-2. Even more surveys are coming online such as TAIPAN/WALLABY, and possible SDSS derived Tully-Fisher samples. All these data will provide us first class information on the cosmology and gravity on the scales of Large Scale Structures. However, there have been large debate in the past due to the complexity of the analysis (Malmquist biases, calibration uncertainties, edge effects, ...).In this talk, I will present two new methods of analysis of distance data which have been extensively tested. They are both proven to be largely bias free and provide unique insight in the dynamics of Large Scale Structures. The first is based on the iterative reconstruction using linear theory on galaxy redshift surveys and self-consistent adjustment to distance data. The second invokes the full power of Bayesian analysis to infer the density field, cosmology and distance indicator calibration from raw data. Both of these methods have been applied to actual data, for which I will show and discuss the results.
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12:00 - 12:25 Cristiano PorcianiMyths and truths about halo formation in CDM models
I will discuss the conditions under which dark-matter halos emerge from the linear density field, highlight limitations of the classic excursion-set approach, and propose new directions to explore.
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Oliver HahnDark Matter with Phase Space Elements
I will review the novel approach to use Lagrangian elements in the dynamical analysis and simulation of cosmic structure formation. Unlike N-body particles, these elements provide a continuum approximation to the distribution function of cold collisionless systems, such as dark matter. I will show how such methods can be used to overcome discretization artefacts that have plagued N-body simulations for decades, but also how we gain new insights into the dynamics of the cosmic dark matter fluid through better knowledge of the full fine-grained dynamics that allow e.g. more accurate estimates of density and velocity fields.
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11:44 - 12:01 Elisa ChisariIntrinsic alignments as a probe of cosmology
The intrinsic alignments of galaxies, physical correlations between their shapes, are typically considered as a nuisance for weak gravitational lensing. The progress in our understanding of alignments in the last decade allows us to start thinking of alignments as a cosmological probe. In this talk, I will discuss the potential role of alignments in probing inflation and primordial gravitational waves.
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       12:01 - 12:18 Stefan HilbertIntrinsic alignments of galaxies and halos
Intrinsic alignments of the shapes of galaxies and their surrounding matter are both a nuisance and a signal for astrophysics and cosmology. I will discuss our efforts to better understand these alignments and their impact on large-scale structure observables using large hi-resolution hydrodynamical simulations as well as semianalytic alignment models. I will also compare our model predictions for galaxy and halo shapes and their alignments to measurements in CFHTLenS.
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       12:18 - 12:35 Jia LiuCosmology Constraints from the Weak Lensing Peak Counts and the Power Spectrum in CFHTLenS
Lensing peaks have been proposed as a useful statistic, containing cosmological information from non-Gaussianities that is inaccessible from traditional two-point statistics such as the power spectrum or two-point correlation functions. Using the publicly available data from the 154 deg^2 CFHTLenS survey and a large suite of ray-tracing N-body simulations on a grid of 91 cosmological models, we find that constraints from peak counts are comparable to those from the power spectrum, and somewhat tighter when different smoothing scales are combined.
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12:25 - 13:45 LunchLunch 12:25 - 13:45 LunchLunch 12:35 - 13:50 Lunch
13:45 - 14:10 Jab Niklas GriebCosmological Implication of the DR12 Galaxy Clustering Wedges in Fourier Space
Due to the increased volume of recent galaxy-redshift surveys, anisotropic clustering measurements have become a feasible and prolific cosmological probe. The clustering analysis using multipole moments of the line-of-sight-dependent galaxy correlation function (or alternatively clustering wedges) are already the standard analysis technique for state-of-the-art galaxy-redshift surveys in configuration space. We extend the concept of clustering wedges to Fourier space by averaging the 2D power spectrum $P(\mu,k)$ over two wide bins in the LOS parameter $\mu$. The measurement of Fourier space wedges from a galaxy catalogue is more intricate than for their configuration space counterpart, because, next to other effects, the observed signal is affected by the window function and fibre collisions modulate the signal more significantly. As part of the final BOSS analysis, we measure Fourier space wedges from the DR12 combined galaxy sample. By performing an Alcock-Pacynski test on the baryonic acoustic feature, we extract constraints on the Hubble parameter and angular diameter distance to the mean survey redshift and study how this information is complemented by that encoded in the full broad-band shape of the Fourier space wedges. Such RSD models fits also allows us to constrain the growth of structure and we are able to test the assumptions behind the standard cosmological model to excellent precision. Further, our analysis also analyses the consistency of these results with the ones derived from the angle-averaged power spectrum and Fourier space multipoles, as well as from the wedges and multipoles measured in configuration space.
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Ofer LahavOverview of New Results from the Dark Energy Survey
The Dark Energy Survey (DES) has now completed 2 out of 5 observing seasons.The talk will overview new results based on the early data, from the Milky Way to the high redshift universe. It will also discuss the status of Dark Energy research and the open questions.
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13:45 - 14:02 Alex SzalayRedshift Space Distortions of Galaxy Correlations
The talk will discuss how redshift space distortions due to the motion of galaxies affect a feature in the correlation function due to Baryon Acoustic Oscillations. The talk will also present results from analyzing the SDSS Main Galaxy Survey. We will discuss the impact of using unusual geometries in computing the galaxy correlation function. We show that redshift-space distortions can substantially sharpen the BAO peak in directions close to the line of sight.
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Bridget FalckTesting Gravity in the Cosmic Web
The cosmic web of large scale structure provides a rich test bed for theories of gravity. The key feature of these theories is their screening mechanism which recovers general relativity on Solar System scales. Using cosmological N-body simulations of modified gravity, I will show that the Vainshtein screening mechanism depends on the cosmic web morphology of dark matter particles identified with ORIGAMI, which defines the structures of the cosmic web according to the dimensionality of their collapse. All halos are screened in the Vainshtein mechanism independent of their mass or environment, while filament, wall, and void particles are unscreened independent of their density. This is in contrast to the chameleon screening mechanism, which depends on both the mass and environment of halos and is not a function of the cosmic web morphology of dark matter particles. I will end by discussing the prospect of using cosmic voids instead of halos to test theories of gravity.
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13:50 - 14:07 Christopher BonnettPhotometric redshifts for weak lensing in DES-SVA-1
Accurate estimation of the redshift distribution is crucial for inferring the cosmology. In this talk I will present the efforts made in the Dark Energy Survey with respect to estimation of the redshift distribution using template and Machine Learning methods. Further I'll discuss some of the short comings in the current spectral catalogues and the effect on of the redshift errors on the weak-lensing analysis.
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14:10 - 15:00 Poster TalksPoster Talks 14:02 - 14:19 Cora UhlemannEdgeworth streaming model for redshift space distortions
We derive the Edgeworth streaming model (ESM) for the redshift space correlation function starting from an arbitrary distribution function for biased tracers of dark matter by considering its two-point statistics and show that it reduces to the Gaussian streaming model (GSM) when neglecting non-Gaussianities. We test the accuracy of the GSM and ESM independent of perturbation theory using the Horizon Run 2 N-body halo catalog.While the monopole of the redshift space halo correlation function is well described by the GSM, higher multipoles improve upon including the leading order non-Gaussian correction in the ESM: the GSM quadrupole breaks down on scales below 30 Mpc/h whereas the ESM stays accurate to 2% within statistical errors down to 10 Mpc/h.To predict the scale dependent functions entering the streaming model we employ Convolution Lagrangian perturbation theory (CLPT) based on the dust model and local Lagrangian bias. Since dark matter halos carry an intrinsic length scale given by their Lagrangian radius, we extend CLPT to the coarse-grained dust model and consider two different smoothing approaches operating in Eulerian and Lagrangian space, respectively. The coarse-graining in Eulerian space features modified fluid dynamics different from dust while the coarse-graining in Lagrangian space is performed in the initial conditions with subsequent single streaming dust dynamics, implemented by smoothing the initial power spectrum in the spirit of the truncated Zel'dovich approximation. Finally, we compare the predictions of the different coarse-grained models for the streaming model ingredients to N-body measurements and comment on the proper choice of both the tracer distribution function and the smoothing scale to improve the combined predictions of the redshift space halo correlation function.
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Pablo FosalbaModeling Galaxy Surveys with the MICE Simulations
Exploiting the data from future astronomical surveys requires thedevelopment of new tools for its accurate theoretical modeling. I willpresent MICE, a project led by the observational cosmology group at ICEthat is developing very large numerical simulations using the Marenostrumsupercomputer. In particular, I will present the MICE Grand-challenge lightcone simulation, a state of the art Nbody simulation that is being used to prepare the new generation of astronomical surveys such as DES or Euclid. I will illustrate this by showing how MICE mocks have been recently used to constrain cosmology through the cross-correlation of the DES Science Verification galaxies and CMB Lensing maps.
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14:07 - 14:24 Takashi HamanaCosmological constraints from Subaru weak lensing cluster counts
I will present results of weak lensing cluster counts obtained from 11 sq.deg SuprimeCam data [arXiv:1503.01851]. Although the area is much smaller than previous work dealing with weak lensing peak statistics, the number density of galaxies usable for weak lensing analysis is about twice as large as those. The higher galaxy number density reduces the noise in the weak lensing mass maps, and thus increases the signal-to-noise ratio of peaks of the lensing signal due to massive clusters. This enables us to construct a weak lensing selected cluster sample by adopting a high threshold S/N, such that the contamination rate due to false signals is small. We find 6 peaks with S/N>5. For all the peaks, previously identified clusters of galaxies are matched within a separation of 1 arcmin, demonstrating good correspondence between the peaks and clusters of galaxies. We evaluate the statistical error using mock weak lensing data, and find Npeak=6+/-3.1 in an effective area of 9.0 sq.deg. We compare the measured weak lensing cluster counts with the theoretical model prediction based on halo models and place the constraint on Omega_m-sigma_8 plane which is found to be consistent with currently standard LCDM models. It is demonstrated that the weak lensing cluster counts can place a unique constraint on sigma_8-c_0 plane, where c_0 is the normalization of the dark matter halo mass-concentration relationship. Finally we discuss prospects for ongoing/future wide field optical galaxy surveys.
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    14:19 - 14:36 Teppei OkumuraReconstructing halo power spectrum from galaxy distribution in redshift space
In analyzing galaxy clustering from redshift surveys, one of the most difficult parts to model it is unclear relation between halo and galaxy distributions. While halo motions are well described by bulk flows, motions of galaxies inside halos are virialized motions, known as the Finger of God effect. Reconstructing halo density field from observed galaxy positions is not straightforward because the radial positions of galaxies are distorted along the line of sight (redshift space distortions). In this talk, I will present a method to measure the halo power spectrum from the galaxy distribution. I will also show how well the methods works using mock galaxy catalogs constructed from N-body simulations.
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Pier Stefano CorasanitiBaryon Acoustic Oscillations from the DEUS-FUR simulation
The next generation of galaxy surveys will measure the Baryon Acoustic Oscillations (BAO) signal in the matter power spectrum to unprecedented precision. Current data already probe cosmological distances as encoded in the BAO pattern to a few per-cent accuracy. This calls for accurate theoretical model predictions of the BAO spectrum. In this talk I will present results from the analysis of the DEUS-FUR simulations. In particular I will discuss the implications of non-linear effects on the relevant features of the BAO power spectrum at different redshifts.
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14:24 - 14:41 Konrad KuijkenThe first lensing results from KiDS
The Kilo-Degree Survey, KiDS, is one of the ESO public surveys on the VLT Survey Telescope. The main aim of the survey is to study the distribution of dark matter in the universe from weak gravitational lensing, and the VST is a uniquely capably instrument for this.I will describe the first results from the weak lensing analysis of the first KiDS data releases, as well as show what can be expected as the survey continues to grow in area.
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    14:36 - 14:53 Roman ScoccimarroRedshift space distortions and BOSS
I'll discuss recent developments in modeling redshift space distortions, with emphasis on application to galaxy data in the BOSS samples.
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Oliver FriedrichCosmic Shear Covariances for the science verification data of the Dark Energy Survey
The weak lensing working group of the Dark Energy Survey has put considerable effort into accurately crafting the covariance matrix of the cosmic shear 2-points statistics measured in the DES science verification data. These efforts include the following:- A theory covariance matrix was computed from a halo model, including Gaussian, non-Gaussian and halo sample variance contributions.- A set of 126 to 196 mock catalogs of the size of DES-SV was extracted from 7 independent simulations. Each simulation consists of 3 N-body light cones with co-moving box sizes from 1050 Mpc/h to 4000 Mpc/h. The large volume of the simulations ensures an accurate representation of large scale contributions to the sample covariance of the mock catalogs.- We used log-normal simulations of the convergence and the corresponding shear field to test the performance and stability of internal covariance estimators such as jackknife and bootstrap. We devised optimized estimation schemes that can yield accurate constraints on cosmological parameters.I will give an overview of our work and I will in detail describe our findings on internal covariance estimation. This includes a discussion of systematic effects in covariance estimation that will also be of interest for other 2-point statistical probes such as galaxy clustering.
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14:41 - 14:58 Graham SmithLoCuSS: New constraints on hydrostatic mass bias in galaxy clusters
I will present new weak-lensing mass measurements of a complete sample of 50 galaxy clusters at z=0.2 and describe extensive tests of systematic errors in our analysis. Overall we control systematics at the sub-5% level, and argue that as such these are the most reliable weak-lensing mass measurements to date. I will also present a cross-comparison of our weak-lensing mass measurements with (1) other weak-lensing surveys, (2) our own measurements of the cluster masses using X-ray data, and (3) Planck cluster mass estimates. The picture that emerges is one of 10% non-thermal pressure support in clusters, in tension with some recent claims in the literatire, and supporting the view that the Planck primary CMB and cluster counts remain in tension. This talk will be on behalf of the Local Cluster Substructure Survey (LoCuSS).
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    14:53 - 15:10 Atsushi TaruyaA novel scheme for perturbation theory calculation of large-scale structure
We present a novel scheme for the perturbation theory (PT) calculations of large-scale structure beyond linear theory prescription. Solving the evolution equations for perturbations, we numerically construct the mode-coupling kernels of the PT, from which the power spectrum and/or correlation function can be systematically computed. The scheme is even applicable to the structure formation scenarios in which the analytic construction of PT kernels is no longer possible. As an illustration, we show several interesting results for the power spectrum calculation in modified gravity model.
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Nico HamausA unique composition of emptiness - Cosmic voids as cosmological probes
Redshift surveys measure the location of millions of galaxies in the observable Universe, thereby constructing a three-dimensional map of its large-scale structure. This structure is characterized by dense clusters of galaxies, connected by filaments and sheets of lower number density. The remaining and dominant volume within this cosmic web is taken up by voids, vast regions of relatively empty space. Understanding the internal structure and spatial distribution of voids is crucial when considering them as cosmological probes. I will present some recent advances in modeling average void density- and velocity profiles, as well as their anisotropic clustering statistics in redshift-space on the basis of state-of-the-art N-body simulations and mock galaxy catalogs. While clusters, filaments and sheets have entered various stages of nonlinearity in the past, voids represent structures whose evolution can be described remarkably well by linear theory, suggesting them to be among the most pristine objects to consider for future studies on the nature of dark energy, dark matter and gravity.
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15:00 - 15:50Poster SessionPoster Session 15:10 - 15:40BreakBreak 14:58 - 15:28Break
15:50 - 16:07 Salvador Salazar-AlbornozClustering tomography on the final BOSS survey
We present the results of a tomographic analysis of the final BOSS DR12 sample. We compute the two-point angular auto/cross correlation function in many thin redshift shells, and study the cosmological implications of performing full-shape fits simultaneously to all measurements. As discussed in Salazar-Albornoz et al. 2014, this procedure does not require to assume a fiducial cosmology in order to convert measured angular positions and redshifts into distances, and can provide improved cosmological constraints in certain parameter spaces over those derived from isotropic BAO measurements, specially on the redshift evolution of the dark energy equation of state.
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Shun SaitoSubhalo abundance matching to model galaxy-halo connection in the Baryon Oscillation Spectroscopic Survey
The Baryon Oscillation Spectroscopic Survey (BOSS) in Sloan Digital Sky Survey III (SDSS-III) has observed almost one million massive galaxies at intermediate redshift (z~0.5) through which the measurements of cosmological signals such as the Baryon Acoustic Oscillation scale and the Redshift-Space Distortion are achieved with unprecedented precision. An essential ingredient in analyzing the BOSS galaxies is how to model a link between observed galaxies and simulated dark matter halos. In this talk, we aim at presenting our attempt to model the relation between the BOSS CMASS galaxies and halos in 6-dimensional phase space on the basis of the subhalo abundance matching (SHAM) scheme. Our SHAM approach relies on the deeper catalog in the SDSS Co-Adds in Stripe 82, and hence can naturally incorporate incompleteness effect in a complicated CMASS selection. We will show how models of CMASS-halo connection can be constrained by 3-dimensional clustering signal in redshift space. We will also discuss the implication of our model from galaxy evolution point of view.
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15:40 - 15:57 Ixandra AchitouvImproving reconstruction of the baryon acoustic peak : the effect of local environment
Precise measurements of the baryon acoustic oscillation (BAO) scale in the clustering pattern is a central goal of current and future galaxy surveys. The BAO peak may be sharpened using the technique of density-field reconstruction, in which the bulk displacements of galaxies are estimated using a Zeldovitch approximation. We use numerical simulations to demonstrate how the accuracy of this approximation depends strongly on local environment, and how this information may be used to construct an improved BAO measurement through environmental re-weighting and using higher-order perturbation theory. We outline further applications of the displacement field for testing cosmological models.
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Alexandre BarreiraLensing by galaxy clusters and voids with modified lensing potentials
The growing interest on models of gravity beyond GR is justified by the ability of these models to explain the accelerated expansion of the Universe and also because they help to pinpoint which observational methods can stand a better chance to test gravity on large scales. In this talk, I will focus on two observational aspects that can arise in models that modify directly the gravitational lensing potential. In a first part of the talk, I will use the convergence profiles of 19 CLASH galaxy clusters to estimate their concentration and mass in two theories of gravity: the Cubic Galileon and an example of a Nonlocal model. My results show that the mass and concentration estimates barely change in between these two models and GR. This is attributed to the strong efficiency of the Vainshtein screening in the Cubic Galileon model and to the rather weak fifth force in the Nonlocal gravity model at the cluster redshifts. I will also show that tests of gravity based on comparisons of dynamical and lensing masses estimates can therefore be applied to a model like the Galileon, which was unclear before.In the second part of the talk, I will use the same two models to look at the lensing signal produced by cosmic voids found in N-body simulations. In voids, the density is low and therefore the screening mechanisms in modified gravity are not at play. The fifth force effects are therefore maximal in voids and they amplify the lensing signal via (i) modified dynamics, which makes voids emptier on average and (ii) direct modifications to the lensing potential that enters the photon geodesic equation. I will show the results for the density and force profiles of the voids found in N-body simulations of the two models and use them to compute the associated lensing signal. Compared to GR, the amplitude of the lensing signal is approximately 10% and 100% stronger in the Nonlocal and Galileon models, respectively. This opens good prospects to use voids in tests of gravity, specially after the recent detection of the lensing signal in voids found in SDSS galaxy catalogues (Melchior et al. 2014; Clampitt&Jain 2014).
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15:28 - 15:45 Marguerite PierreFirst results from the XXL-XMM survey
The XXL survey is an XMM Very Large program which covers two 25 deg2 fields at medium X-ray sensitivity. The survey has detected over 500 clusters and 30,000 AGNs to a flux limit of 5E-15 erg/s/cm in [0.5-2]keV. The survey aims to provide a standalone sensitive test of our cosmological model by measuring the growth of structure as traced by clusters and AGNs. Primary X-ray observations were completed in 2013 and we will describe the XMM data set in addition to our multi-wavelength follow-up campaign, including an ESO Large Programme. We will also summarise the main science themes engaged by the XXL survey including the computation of a realistic selection function and a series of early results generated for the sample of 100 brightest clusters detected in the survey. Website of the survey: http://irfu.cea.fr/xxl
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16:07 - 16:24 Cullan HowlettBAO and RSD measurements at z=0.15 with the SDSS Main Galaxy Sample
I will present a four percent measurement of the cosmic distance scale from Baryon Acoustic Oscillations, and complimentary measurements of the growth rate of structure from Redshift Space Distortions, at an effective redshift of 0.15. These measurements were made using a sample of ~60,000 luminous red galaxies drawn from Data Release 7 of the Sloan Digital Sky Survey, and are ideally placed to fill a niche between existing measurements from the 6dFGRS and BOSS surveys. The relatively low redshift of this galaxy sample allows for a precise measurement of the dark energy equation of state. The methods used to produce these results, including the development of a new code to generate an accurate sample of 1000 mock galaxy catalogues, will also be presented.
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Yen-Ting LinOn detecting halo assembly bias with galaxy populations
The fact that the clustering and concentration of dark matter halos depend not only on their mass, but also the formation epoch, is a prominent, albeit subtle, feature of the cold dark matter structure formation theory, and is known as assembly bias. At low mass scales (~10^12 Msun/h), early-forming halos are predicted to be more strongly clustered than the late-forming ones. In this study we aim to robustly detect the signature of assembly bias observationally, making use of formation time indicators of central galaxies in low mass halos as a proxy for the halo formation history. Weak gravitational lensing is employed to ensure our early- and late-forming halo samples have similar masses, and are free of contamination of satellites from more massive halos. For the two formation time indicators used (resolved star formation history and current specific star formation rate), we do not find convincing evidence of assembly bias. For a pair of early- and late-forming galaxy samples with mean mass M200c~9x10^11 Msun/h, the relative bias is 1.00+-0.12. We attribute the lack of detection to the possibilities that either the current measurements of these indicators are too noisy, or they do not correlate well with the halo formation history. Alternative proxies for the halo formation history that should perform better are suggested for future studies.
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15:57 - 16:14 Fabian SchmidtA complete parametrization of galaxy bias
I will describe a general and rigorous parametrization of galaxy bias, which encodes the relation between a general tracer and matter in an unambiguous and non-redundant way at any given order in perturbation theory. This can be used to connect the observed statistics of galaxy clustering with the initial conditions to learn about inflation. Also, the physical interpretation of the (renormalized) bias parameters can inform models of galaxy formation.
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Yan-Chuan CaiConstraining Cosmology using Cosmic Voids
Cosmic voids found in large-scale structure have emerged as a new area of study in cosmology. I will briefly summarise major activities on this frontier in theory and observations. I will demonstrate the unique power of voids for distinguishing general relatively from theories of modified gravity. Two observables will be focused, 1.) The weak gravitational lensing signal associated with voids, which measures the dark matter content in voids, and requires the combination of a spectroscopic redshift survey with a weak lensing survey. 2.) stacking of voids for the Integrated Sachs-Wolfe effect.
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15:45 - 16:02 Rishi KhatriConstraints on the thermal Sunyaev-Zeldovich effect and $\mu$-type distortion fluctuations and primordial non-Gaussianity from Planck data
I will present all sky maps of the Sunyaev-Zeldovich effect (SZ) and $\mu$-type distortion fluctuations calculated from the full mission Planck data using the recently proposed approach to component separation based on parametric model fitting and model selection. The model selection approach allows us to distinguish between the CO line emission and the SZ effect and also between the SZ effect and the $\mu$-type distortions, something that is not possible using the internal linear combination based methods. I will present a new CO mask which covers the regions with significant CO emission designed specifically for the SZ effect studies. I will present new limits (lower and upper) on the average $y$-type distortion by combining the Planck and the SPT data. I will also present constraints on the $\mu$-type distortion fluctuation amplitude, power spectrum and cross-power spectrum (with the primary CMB) and discuss implications for the primordial non-Gaussianity.
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16:24 - 16:41 Rupert CroftGravitational redshifts and lyman-alpha emission intensity: results from SDSS/BOSS
The enormous number of spectra in modern cosmology surveys has opened up the possibility to search for physical effects that were not part of survey planning. These nevertheless may contain valuable information and guide the design of future instruments. I will present brief results from two analyses of the BOSS galaxy redshift survey, one a search for gravitational redshifts caused by the large-scale structure of the Universe and the other a measurement of three dimensional clustering in the cosmological lyman-alpha emission intensity.
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Julien BelCosmological constraints from the galaxy power spectrum of VIPERS
VIPERS is a spectroscopic redshift survey presenting a unique sampling rate at high redshift. I will briefly show the technicalities of the estimation of the galaxy power spectrum in the VIPERS. Then I will concentrate on showing that the high redshift range probed allows a significant gain in the accuracy of the modeling of the galaxy power spectrum. I will finally show the cosmological constraints that we obtained, specially the measurement of the matter density parameter and the baryon fraction.
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16:14 - 16:31 Zvonimir VlahOn the Statistics of Biased Tracers in the Effective Field Theory of Large Scale Structures
With the completion of the Planck satellite, in order to continue to gather cosmological information it has become crucial to understand the Large Scale Structures (LSS) of the universe to percent accuracy. The Effective Field Theory of LSS (EFTofLSS) is a novel theoretical framework that aims to develop an analytic understanding of LSS at long distances, where inhomogeneities are small. We present the further developed description of biased tracers in the EFTofLSS to account for the effect of baryonic physics and primordial non- Gaussianities, finding that new bias coefficients are required. Then, restricting to dark matter with Gaussian initial conditions, we present the prediction of the EFTofLSS for the one-loop two-point functions, and for the tree-level three-point functions. Several new bias coefficients are needed in the EFTofLSS, even though their contribution at a given order can be degenerate and the same parameters contribute to multiple observables. We will present the comparison of our results with the output of N-body simulations.
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Panel Discussion 16:02 - 16:27 Simon WhiteSummary talk
I will discuss issues arising in the LSS field and from the topics discussed at the meeting.
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16:41 - 16:58 Elisabeth KrauseCombining Probes of Large-Scale Structure in the Precision Cosmology Era
Current and upcoming wide-field large-scale structure surveys will enable precision measurements of various observables of large-scale structure, such as weak lensing, galaxy clustering, and the abundance of galaxy clusters. These observables probe different aspects of cosmic structure formation, and combining them improves constraints on cosmology significantly. However, these observables probe the same underlying density field, and the information content is correlated. Additionally, they share correlated (astrophysical and observational) systematic effects.In this talk I will introduce the analysis concepts for the joint analysis of probes of large-scale structure currently under development for CosmoLike, a fast and self-consistent LSS likelihood analysis package. I will discuss cross-correlations of observables, and modeling and mitigation of systematic uncertainties affecting multiple probes, and in particular give a quantitative comparison of different weak lensing systematics.
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Faizan Gohar MohammadMeasurement of the growth rate of structure f(z) from cross-correlations in VIPERS final data release
The recently completed VImos Public Extragalctic Redshift Survey (VIPERS) provides us with an unprecedented sample of galaxies spanning a redshift range between 0.5-1.2 with a high sampling rate. The final sample contains measurements of positions and spectroscopic redshifts of ~100,000 galaxies. This, combined with the high quality photometric data from the same regions in CFHTLS survey allows us to efficiently draw clean volume limited catalogs from the full galaxy sample. We perform a measurement of f(z) through modelling the RSD signal from cross-correlating volume limited catalogs of blue and luminous red galaxies. This results in a constraint on f(z), at an effective redshift of z~0.8, complementary to the classical measurements from the galaxy auto-correlation function.
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16:31 - 16:48 Nuala McCullaghExtracting non-Gaussian Information from Large-scale Structure
As future surveys such as Euclid prepare to deliver vast amounts of galaxy clustering data, it is becoming increasingly important to develop theoretical tools for exploiting the full cosmological information contained in the data. The two-point statistics of the matter density field have been widely used as probes of cosmological information. However, because the density field is non-Gaussian on nonlinear scales, additional information resides in higher-point statistics of the distribution. Extracting this information requires accurate modeling of both nonlinearity and redshift-space distortions. First, I will discuss the challenges associated with modeling these effects in higher-point statistics of the density field. Next, I will discuss how density transformations may provide a simple method for restoring higher-order information to the 2-point statistics.
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17:58 - 17:15 Shahab JoudakiTesting Gravity on Cosmic Scales with Weak Lensing and Redshift Space Distortions
The apparent existence of "dark energy" compels us to test the laws of gravity across the scale of the universe in multiple ways. Only a powerful combination of two observables, gravitational lensing and galaxy velocities, will pin down the physics of gravity. In this talk I will present new tomographic weak lensing measurements from the largest existing cosmic shear survey, the Red Cluster Sequence Lensing Survey (RCSLenS), marginalizing over systematic uncertainties from intrinsic alignments, baryons, and photometric redshifts. I will then discuss standard cosmology and modified gravity constraints from these RCSLenS measurements (along with CFHTLenS) in combination with overlapping spectroscopic surveys like WiggleZ and BOSS. The covariance between the RSD monopole and quadrupole spectra, shear-galaxy correlation function, and shear-shear correlation functions has been fully incorporated, and the corresponding code will be publicly released.
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Khee-Gan Lee3D Mapping of z~2-3 Large-Scale Structure with IGM Tomography
The hydrogen Ly-a forest absorption is a well-known tracer of high-redshift (z>2) large-scale structure, which is traditionally studied along 1D sightlines in front of bright quasars. By instead using faint galaxies (~24th mag) at high area densities as background sources, we are able to study the large-scale IGM in 3D by tomographically reconstructing the absorption across adjacent lines-of-sight. This allows us to efficiently map out cosmological volumes (V~ 10^6 h^{-3} Mpc^3) while simultaneously probing scales down to a few cMpc. This opens up a wealth of science possibilities, including studying the link between high-redshift galaxies and the IGM, efficiently finding galaxy protoclusters, studying high-redshift voids and LSS topology. I will describe pilot observations using this technique, as well as upcoming and near-future surveys.
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16:48 - 17:05 Alvise RaccanelliTesting cosmological models with galaxy clustering
The strangest feature of our current cosmological model is the observation that the expansion rate of the universe is accelerating. Our ignorance is summarized by the simple name for the cause of the observed phenomenon: dark energy. Alternatively, it could be explained by the break down of Einstein's gravitation theory on cosmological scales. Observations of large-scale structure have played an important role in developing our standard cosmological model and will play an essential role in our investigations of the origin of cosmic acceleration.I will illustrate how it is possible to test different models of gravity and dark energy via galaxy clustering using forthcoming cosmological galaxy surveys.However, the theoretical models currently used to interpret the data often rely on simplifications that make them not accurate enough for precise measurements at very large scales.I will show improvements to the theoretical modeling that arise when using a proper general relativistic formalism, in particular focusing on lensing terms in radial correlations. I will show how, in wide and deep surveys, those corrections will need to be taken into account if we want to measure cosmological parameters with high precision without introducing systematic errors.
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17:15 - 17:32 Fergus SimpsonRedshift Space Distortions from the Clipped Galaxy Field
I will present the first cosmological constraints derived from a clipped galaxy density field. By enforcing an upper bound on the galaxy number density field in the Galaxy and Mass Assembly survey (GAMA), contributions from the nonlinear processes of virialisation and galaxy bias are greatly reduced. Clipping is found to extend the applicability of the conventional Kaiser prescription by more than a factor of three in wavenumber, or a factor of thirty in terms of the number of Fourier modes.
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Andrew PontzenWhat can we learn from large-scale astrophysical distortion of the Lyman-alpha forest?
BOSS has demonstrated that it is possible to use the Lyman-alpha forest in multiple quasar spectra to recover the correlation function of neutral HI on scales up to at least 200 Mpc comoving. Forthcoming spectroscopic surveys like DESI will use up to a million quasars to achieve a beautifully precise measurement of this crucial probe of structure formation.While the primary aim of these surveys is to recover cosmological information (especially through the BAO feature), much more can be learnt from the observations. In this talk I will review our understanding of how astrophysical effects, particularly ionisation and thermal fluctuations, affect the measured HI fluctuations - and how, counterintuitively, the magnitude of these astrophysical corrections increases with scale. I will discuss future prospects for recovering astrophysical information and debiasing cosmological results. (See arXiv 1402.0506 and 1407.6367.)
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17:05 - 17:22 Jens JascheInferring past and present cosmic structures from observations
Presently proposed and designed future cosmological probes and surveyspermit us to anticipate the upcoming avalanche of cosmological informationduring the next decades. The increase of valuable observations needs to beaccompanied with the development of efficient and accurate informationprocessing technology in order to analyse and interpret this data.Besides traditional systematics and uncertainties such as surveygeometries and observational noise, modern data analysis needs to accountfor the complex statistical properties of gravitationally evolved matterfields and also has to provide corresponding uncertainty quantification.The analysis of the structure and evolution of ourinhomogeneous Universe therefore requires to solve non-linear statisticalinference problems in very high dimensional parameter spaces, involving onthe order of 10^7 or more parameters. For these reasons, in this talk Iwill address the problem of high dimensional Bayesian inference fromcosmological data sets via therecently proposed BORG algorithm. This method couples an approximate modelof structure formation to an Hybrid Monte Carlo algorithm providing afully probabilistic, physical model of the non-linearly evolved densityfield as probed by galaxy surveys. Besides highly accurate and detailedmeasurements of three dimensional cosmic density and velocity fields, thismethodology also infers plausible formation histories for the observedlarge scale structure. In this talk I will give an overview over thispromising path towardsBayesian chrono-cosmography, the subject of inferring the four dimensionalstate of our Universe from observations.
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17:32 - 17:49   Silvia BonoliThe J-PAS survey
I will present a brief overview of the J-PAS project: A galaxy survey carried out from Teruel (Spain) that will map 8500sq deg with 56 narrow-band filters. I will discuss the current status of the project and the potential it offers for cosmological and galaxy formation studies.
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