Program

Long-talk Information

The 1st week

11th Nov (Mon)

Speaker: Kazuya Koyama 

Title: Theory activities in Euclid

Abstract: 

I will present results from activities within the theory working group in the Euclid collaboration. Our main focus is the forecasts for Euclid’s abilities to constrains models beyond Lambda-CDM models. I will also present the efforts to validate the pipeline in beyond Lambda-CDM models including the comparison of N-body simulations, measurements of the power spectrum and mass function and the implementation of emulators to the likelihood code. 

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12th Nov (Tue)

Speaker: Giovanni Cabass

Title: BOSS Constraints on Massive Particles during Inflation: The Cosmological Collider in Action

Abstract: 

Massive spinning particles leave imprints on primordial non-Gaussianity via their coupling to the inflaton, even despite their exponential dilution during inflation. Improving on modern Cosmological Bootstrap techniques I present a search for these particles using the redshift-space galaxy power spectrum and bispectrum multipoles measured in BOSS, the first analysis of such kind with cosmological data. I focus on spin-0 particles in the principal series and constrain their couplings to the inflaton at varying speed of propagation and mass, marginalizing over the unknown inflaton self interactions. This is a fundamental step towards inflationary spectroscopy from cosmological observations, the ultimate link between the physics of the infinitely large and infinitely small.

Speaker: Masahiro Takada

Title: TBA

Abstract:  TBA

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13th Nov (Wed)  -- one-day workshop --  Click here

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14th Nov (Thu)

Speaker: Alexandre  Barthelemy

Title: Modelling of realistics lensing PDFs in data from first-principles

Abstract: TBA

Speaker: Giovanni Cabass

Title: Cosmological Information in Perturbative Forward Modeling

Abstract: 

I discuss how well perturbative forward modeling can constrain cosmological parameters compared to conventional analyses. In perturbation theory the field-level posterior can be computed analytically in the limit of small noise. In the idealized case where the only relevant parameter for the nonlinear evolution is the nonlinear scale, I argue that information content in this posterior is the same as in the n-point correlation functions computed at the same perturbative order. In the real universe other parameters can be important, and there are possibly enhanced effects due to nonlinear interactions of long and short wavelength fluctuations that can either degrade the signal or increase covariance matrices. I discuss several different parameters that control these enhancements and show that for some shapes of the linear power spectrum they can be large. This leads to degradation of constraints in the standard analyses, even though the effects are not dramatic for a ΛCDM-like cosmology. The aforementioned long-short couplings do not affect the field-level inference which remains optimal. Finally, I show how in these examples calculation of the perturbative posterior motivates new estimators that are easier to implement in practice than the full forward modelling but lead to nearly optimal constraints on cosmological parameters.

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15th Nov (Fri)

Speaker: Teppei Okumura

Title: Constraining cosmology with galaxy intrinsic alignment

Abstract: 

I will talk about constraining cosmology focusing on intrinsic alignments of galaxy shapes in both theoretical and observational aspects. 

Speaker: Fabian Schmidt

Title: Cosmology from galaxy clustering: field-level vs summaries

Abstract: 

I will review new results on field-level cosmology inference from galaxy clustering, in particular on sigma_8 and the BAO scale, and compare with the constraints obtained using standard analysis techniques. I will then discuss where the additional information found at the field level could come from.   

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The 2nd week

18th Nov (Mon)

Speaker: Takahiro Nishimichi

Title: Dark Quest II Project

Abstract: 

I will present the current status of the Dark Quest II Project.

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19th Nov (Tue)

Speaker: Massimo Pietroni

Title: Towards model independent analyses of the Large Scale Structure

Abstract: TBA

Speaker: Ken Osato

Title: Multi-wavelength Cosmological Simulations for Stage-IV Surveys

Abstract:

The Stage-IV cosmological surveys will cover the widest areas with superb image quality. The high-fidelity observational data will enable the measurement of cosmological statistics at unprecedented precision. In the statistical analysis, simulations are critical to estimate possible systematic uncertainties and cosmic variances. To this end, the simulations are required to cover the large volume of Stage-IV surveys and a large number of independent realizations is also important to robustly estimate the covariance matrix of cosmological statistics. Furthermore, the cross-correlations of different observables, e.g., galaxy-galaxy lensing, are employed to extract more information from the Stage-IV survey data. For the cross-correlations, multiple observables must be modelled in simulations, in a correlated manner.

In this talk, I will introduce the recent campaign to construct a suite of multi-wavelength cosmological simulations conducted with the supercomputer Fugaku. We first produce the large suite of dark-matter only simulations and post-process them to generate various mock observations: weak lensing, cosmic microwave background, and galaxy distributions. I will discuss the applications of the simulation data in the data analysis of upcoming cosmological surveys such as Euclid.

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20th Nov (Wed)

Speaker: Benjamin Bose

Title: Towards New Cosmological Perspectives with Neural Networks and Euclid

Abstract: 

In this talk, I will explore the promise of Euclid to go beyond standard ΛCDM consistency tests, allowing more detailed exploration of cosmological theories, and potentially providing a shift towards a new concordance model. I will focus on the key modeling and computational challenges necessary to realize this potential. Special attention will be given to the role of neural networks, both in current applications and future prospects, with the forthcoming galaxy data. 

Speaker: Takahiro Matsubara

Title: The integrated perturbation theory for cosmological tensor fields

Abstract:

Selected topics and results from my latest series of papers on the integrated perturbation theory for cosmological tensor fields (Papers I-IV) are presented. I have formulated a nonlinear perturbation theory for cosmological tensor fields in general. Cosmological tensor fields correspond to observable properties of astronomical objects, such as the spatial distribution of galaxy number density (scalar), angular momentum (pseudo-vector), and shapes (tensors of rank 2 and higher). To take advantage of rotational symmetry, the formalism is constructed based on the irreducible decomposition of tensors, which identifies physical variables that remain invariant under the rotation of the coordinate system. The projection effects onto the sky, which are more directly related to the observations, are also taken into account. Symmetric properties in the projected tensor fields, such as rotation, parity, flipping, and complex conjugation, are made explicit. Extensions of the formalism from the distant-observer approximation to a full-sky formalism are also presented.

References:

T. Matsubara, PRD 110, id.063543 (2024) [arXiv:2210.10435] (Paper I)

T. Matsubara, PRD 110, id.063544 (2024) [arXiv:2210.11085] (Paper II)

T. Matsubara, PRD 110, id.063545 (2024) [arXiv:2304.13304] (Paper III)

T. Matsubara, PRD 110, id.063546 (2024) [arXiv:2405.09038] (Paper IV)

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21st Nov (Thu) -- one-day workshop --  Click here

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22nd Nov (Fri)

Speaker: Martin Crocce

Title:  Modeling nonlinearities in Euclid

Abstract: 

Over the past decades galaxy surveys have provided a wealth of information on the large-scale structure distribution of galaxies, and key information to establish our current cosmological model, LCDM. Future missions, such as EUCLID or DESI will achieve datasets orders of magnitude bigger and have the potential to revolutionize our understanding of the late time Universe. To exploit them we first need to develop robust and accurate modeling, with particular emphasis on information on nonlinear scales. In this talk I will present ongoing work on understanding effects relevant to both redshift and imagining datasets (i.e. galaxy clustering and weak lensing) such as dark matter clustering, galaxy biasing and redshift space distortions, how we model them with perturbation theory and how we test those models against simulations.