Program
| JST UTC +9 |
5th Dec. (Mon.) |
6th Dec. (Tue.) |
7th Dec. (Wed.) |
8th Dec. (Thu.) |
9th Dec. (Fri.) |
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| 9:30- | |||||
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| 10:00 - 10:30 | [PDF] |
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| 10:30 - 11:00 | [PDF] |
(Short talk) [PDF] |
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| 11:00 - 11:30 | [PDF] |
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| 11:30 - 12:00 | [PDF] |
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| 12:00 - 12:30 | [PDF] |
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| 12:30 - 13:00 | (12:30-14:00) |
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| 13:00 - 14:30 | |||||
| Chair | |||||
| 14:30 - 15:30 | [PDF] |
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(14:00-15:00) [PDF] |
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| 15:30 - 16:00 | [PDF] |
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(15:00-15:30) [PDF] |
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| 16:00 - 16:30 | (15:30-16:00) |
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| 16:30 - 17:00 | [PDF] |
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(16:00-16:30) [PDF] |
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| 17:00 - 18:00 | [PDF] |
(16:30-17:00) [PDF] |
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| 17:30 - 18:30 | [PDF] |
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Other cells: Contribution talks (30 minutes)
Asterisks: Remote presentations via the Zoom connection
[5th December (Monday)]
Atsushi Taruya
Opening addressSukhdeep Singh (Invited)
Updates on IA measurements from SDSS and illustris-TNG
TBA
Jonathan Blazek
Simulating intrinsic alignments without hydrodynamics
Modern hydrodynamic simulations, such as Illustris-TNG, provide a valuable window into how realistic galaxy shapes and alignments form in a cosmological context. However, these simulations require “sub-grid” physical assumptions which can impact the observed alignment behavior. Moreover, they are computationally intensive, requiring a large dynamic range, thus limiting the overall volume that can be simulated. As a complementary approach, several groups are developing semi-analytic and AI/ML methods that can be applied to gravity-only simulations to add realistic galaxy alignments. These methods enable the fast generation of large galaxy samples with IA, with a wide range of applications, including model and analysis validation, predictions for novel statistics, covariance estimation, and exploration of alignment mechanisms. In this talk, I will highlight some of the recent work in this area by my group and others, focusing in particular on modeling IA with dark matter halo information. I will also briefly discuss some ideas for using these simulation methods for probing fundamental physics with IA.
Noam Libeskind (Invited)
Cosmic Angular momentum and alignment
Although structures in the Universe form on a wide variety of scales, from small dwarf galaxies to large super clusters, the generation of angular momentum across these scales is poorly understood. In this talk I will discuss how halo and galaxy spins are aligned with large structures that comprise the cosmic web. I will provide some ideas on how such alignments originated. I will also describe how these alignments depend on the nature of dark matter and how they can thus be used as a probe of the cosmological model. Lastly, I will present the possibility that filaments of galaxies—cylindrical tendrils of matter hundreds of millions of light years across—are themselves spinning. By stacking thousands of filaments together and examining the velocity of galaxies perpendicular to the filament's axis (via their redshift and blueshift), we find that these objects too display vortical motion consistent with rotation, making them the largest objects known to have angular momentum. These results signify that angular momentum can be generated on unexpectedly large scales.
Koichiro Nakashima
RSD analysis with Lyman alpha forest including non-linearities
The Lyman alpha forest (LAF), a series of HI absorption lines in the quasar spectra, can be a strong tool for cosmology at redshifts (z>2) that are generally hard to access with other probes. We present a measurement of the LAF anisotropic power spectrum from the hydrodynamic simulations and analyze the full shape to measure the growth rate of the structure through redshift space distortions. Looking ahead to future observations, we tested the validity of the models presented in previous research under different maximum wavenumbers used in the fit. In addition, we indicate the requirements of survey parameters in the assumption of Subaru Prime Focus Spectrograph.
Keitaro Ishikawa
BAO measurement of three-dimensional correlation function for photometric surveys
Galaxy surveys are of two types: spectroscopic and photometric. Spectroscopic observations provide the exact redshift of galaxies, but only bright galaxies can be observed. On the other hand, photometric observations have the advantage which could image faint galaxies at the same time, so we can expect statistical accuracy because we can secure an adequate number of samples. However, photometric observations have a large degree of uncertainty in estimating the redshift to galaxies. For that reason, in our study, we use Baryon Acoustic Oscillation to show the levels we have to achieve systematic error (photo-z error) associated with the photometric observation. To this end, we modeled the photo-z effect by incorporating the photo-z Gaussian distribution integrated into the three-dimensional two-point correlation function and verified the effect using mocks. As a result, the following three things were found. First, in the case that the magnitude of photo-z error associated with the data is known, the position of the BAO peak would be restricted to 4% with a 2σ statistical error when the simulation data including photo-z error equivalent to 50 Mpc/h is used because the photo-z error effect can be integrated into the models. Even if the magnitude of the photo-z error is not known, fitting with the spec-z template or the photo-z 1% template will not bias the BAO location (although the statistical error will be larger). Next, up to a photo-z error corresponding to about 50 Mpc/h, the 3D two-point correlation function can be used for cosmological tests. Finally, even if the photo-z distribution is not Gaussian but skewed non-Gaussian, we showed that skewness doesn’t affect the BAO measurement as long as the mean and variance of the distribution are reproduced correctly. In summary, in our presentation, we will arrange the condition to measure BAO robustly, and then discuss the levels required for photometric observations.
[6th December (Tuesday)]
Simon Samuroff (Invited)
Direct constraints on intrinsic alignments using real data from DES and eBOSS
In this talk I will discuss direct measurements of intrinsic alignments using cross-correlations between DES and eBOSS galaxy catalogues. I will begin with a brief overview of the state of the field and the best IA constraints to-date from various sources. I will then present new results using DES and eBOSS in more detail. This will include discussion of the luminosity-IA relation, and how the relatively large volume of DES can help shed light here. I will also discuss the colour dependence of the IA signal, and consider whether a simple red/blue colour classification (commonly assumed for modelling purposes) could be insufficient for properly understanding IAs with the precision of current and future data sets.
Teppei Okumura
Constraints on growth rate with intrinsic ellipticity correlations of SDSS BOSS galaxies
In this talk, I present constraints on the growth rate of the density perturbation of the universe from intrinsic alignments of galaxies observed by the SDSS Baryon Oscillation Spectroscopic Survey (BOSS). We measure the gravitational shear-intrinsic ellipticity (GI) correlation and intrinsic ellipticity-elliptcity (II) correlation functions over 0.16 < z < 0.7 using LOWZ and CMASS galaxy samples. We detect a clear anisotropic signal of intrinsic alignments. By combining the measurements of the intrinsic ellipticity correlation functions with those of the conventional galaxy density correlation functions, we obtain tighter constraints on the growth rate.
Toshiki Kurita
Constraints on anisotropic primordial non-Gaussianity from intrinsic alignments of SDSS-III BOSS galaxies
Physical correlations of galaxy shapes in the large-scale structure, called intrinsic alignments (IA), recently have been considered as a new tracer of the gravitational tidal field, potentially providing unique information about the large-scale structure of the universe. In this work, we developed an estimator to measure the 3-dimensional IA power spectrum from the 3d position distribution of galaxies and their projected shape (ellipticity) which can be inferred from the combination of two types of actual galaxy surveys, spectroscopic and imaging surveys, respectively. We applied our estimator to BOSS LOWZ+CMASS galaxies and measured the 3-dimensional IA power spectrum for the first time. Furthermore, several studies predicted, both analytically and numerically, that the IA power spectrum can be used to probe the anisotropic primordial non-Gaussianity through its scale-dependent linear shape bias imprinted on the IA power spectrum. We use the measured IA power spectrum to constrain the amplitude of the anisotropic primordial non-Gaussianity. In my talk, I will show the measured IA signals from BOSS galaxies and the obtained constraints on the anisotropic primordial non-Gaussianity.
Hironao Miyatake (Invited)
Weak Lensing Cosmology from Subaru Hyper Suprime-Cam Survey
The accelerating expansion of the universe is one of the most mysterious phenomena. The cosmic acceleration implies the existence of dark energy or the breakdown of Einstein’s general relativity. Either way, revealing the source of cosmic acceleration can result in a paradigm shift in the field of modern physics. Weak gravitational lensing is a small, coherent distortion of distant galaxy images due to gravitational potential, which allows the direct measurement of dark matter spatial distribution. Weak lensing is one of the most powerful cosmological probes because of its capability to measure the nature of cosmic acceleration through the evolution of the large-scale structure of the universe. Hyper Suprime-Cam (HSC), a newly developed prime focus camera at Subaru Telescope, started a wide, deep galaxy imaging survey in 2014, covering ~1,100 sq. degrees of the sky down to the i-band limiting magnitude of 26. The wide field of view, light-gathering power, and superb image quality of HSC make it possible to measure the weak lensing distortion with unprecedented precision. In this talk, I will present weak lensing cosmology results from the HSC survey first-year data, including the overview of the HSC instrument, construction of galaxy shape catalog for weak lensing measurement, and cosmological constraints from cosmic shear and the combination of galaxy-galaxy lensing and clustering. I will also present the prospect of HSC third-year cosmology analyses.
Masanori Iye
Search for symmetry breaking in the spin parity distribution of galaxies
Since all the spirals are trailing, we can use the spiral winding sense, S-wise or Z-wise as projected on the sky, to judge the sign of the line-of-sight component of the spin vector of spiral galaxies. We created spin parity catalogs of 44k spirals with redshift less than 0.05 from the PanSTARRS image archive and 80K spirals with redshift less than 0.8 from HSC image archve. Several studies to search for any trend away from the random distribution are carried out to probe into the origin of spin angular momentum distribution of galaxies. This is a robust method complementary to the approach using the distribution of the axis-ratio and position angle of galaxies.
Ue-Li Pen
Helicity of alignments
Recent claims of parity-odd 4 point functions correspond to helicity violating alignments. I describe the relationships, and observational constraints.
Benjamin Joachimi (Invited)
One alignment model to fit them all?
A comprehensive and predictive model of intrinsic alignments is vital for confidently calibrating cosmology and to gain a deep understanding of the physics linking galaxies to their dark matter environment. But how can we build a model that consistently fits a broad variety of galaxy populations, probes, scales, and survey specifics? I will make the case that forward modelling through simulations, combined with semi-analytic models that build on dark matter halo properties, is a promising approach to capture the full complexity of intrinsic alignments, highlighting recent insights, current efforts, and future directions.
[7th December (Wednesday)]
Rachel Mandelbaum (Invited)
Simulating intrinsic alignments: from hydrodynamical simulations to deep learning generative models
Cosmological hydrodynamical simulations have in recent years become a valuable tool for probing the physics of intrinsic alignments. I will begin by describing some recent results on the use of these simulations to probe alignments, including the connection between IA and morphology, and constraints on IA models using these simulations. Next, I will discuss some of the limitations of cosmological hydrodynamical simulations for this purpose, including dependence on subgrid physics and difficulty in simulating large volumes. Finally, I will describe work that overcomes the last of these challenges, using deep learning to develop generative models of intrinsic alignments that can be applied to large-volume N-body simulations to produce mock catalogs. This work will be placed in the broader context of the field, including comparison between mock catalog production methods and their potential use for validating IA mitigation methods in the context of cosmological weak lensing analysis.
Jounghun Lee
Peculiar Tidal Connections of the Galaxy Stellar Spins
I will present how differently the galaxy stellar spins are aligned with the large-scale tidal field compared with the dark matter spins.
Andrés Alejandro Plazas Malagón (Invited)
THE VERA C. RUBIN OBSERVATORY LEGACY SURVEY OF SPACE AND TIME
The Vera C. Rubin Observatory, currently under construction on Cerro Pachón in Chile, will feature an 8.4-meter telescope, the largest digital camera in the world for astronomy (3200 megapixels), an automated data processing system, and an online public engagement platform. Rubin will conduct the Legacy Survey of Space and Time (LSST), and it will operate on an automated cadence, capturing an area the size of 40 full moons and returning to the same area of sky approximately every three nights after imaging the full sky. The Rubin Observatory was the top-ranked large ground-based project in the 2010 Astrophysics Decadal Survey, and it will advance science in four main areas: the nature of dark matter and understanding dark energy, cataloging the Solar System, exploring the changing sky, and Milky Way structure and formation. Engineering and then science first light is expected in 2023 and full operations for the ten-year survey commencing in the second half of 2024.
[8th December (Thursday)]
Ken Osato
Intrinsic alignments with galaxy formation hydrodynamical simulations
Numerical simulations of the large-scale structures is a powerful tool to study intrinsic alignments since nonlinear growth of structures is taken into account down to small scales. Furthermore, galaxy formation hydrodynamical simulations enable one to generate realistic galaxy images and we can calibrate the analysis pipeline by leveraging these galaxy mocks. In this talk, I will present realistic mock galaxy catalogues produced based on stellar population synthesis from hydrodynamical simulations IllustrisTNG and cosmological implications of correlations of galaxy shapes.
Daiki Osafune
Spin-Alignment of Dark Matter Subhaloes
In the current standard cosmological model, massive dark matter halos are formed through the merger and accretion of smaller dark matter halos. Previous studies suggested that there is a correlation between the direction of the angular momentum vector of the dark matter halos and the large-scale structure filaments. However, it has not been clear what causes this correlation. In this study, we investigated the evolution of the direction of angular momentum of the subhalo, the substructures of the dark matter halo. Using cosmological N-body simulation data nu2GC-S (Ishiyama et al. 2015) and Phi-4096 (Ishiyama et al. 2021), we analyzed the angle between the angular momentum vectors of the subhalo and the host halo (Spin-Alignment). We found that the subhaloes at the center of the host halo tend to coincide in the Spin-Alignment, while the subhaloes at the outskirts of the host halo are randomly oriented. This result suggests that the subhalo’s angular momentum is affected by the host halo as well as the large-scale structure. In this presentation, I will discuss the relationship between the kinematics of the subhaloes in the host halos and the Spin-Alignment.
Jingjing Shi
Intrinsic alignment of galaxy clusters
TBA
Shogo Ishikawa
Intrinsic alignment from the subhalo distribution
Numerical simulations reveal that the signals of intrinsic alignments (IAs) contain cosmological information, such as the feature of the baryon acoustic oscillation (BAO). However, most of previous studies used dark matter particles as a tracer of background density fluctuation for measuring shapes of dark haloes and correlations of IAs. To test the possibility to derive cosmological information from IAs only using observables, we are now measuring IA correlations from the subhalo distribution. In this talk, we show our preliminary results and briefly discuss the effect of projection along line-of-sight that corresponds to uncertainties of photometric redshifts on measuring the BAO feature.
Kazuyuki Akitsu (Invited)
Measurement of the second-order shape biases with full 3D information in simulations
TBA
Takahiko Matsubara
The integrated perturbation theory for cosmological tensor fields
In order to extract maximal information about cosmology from the large-scale structure of the Universe, one needs to use every bit of signals that can be observed. Beyond the spatial distributions of astronomical objects such as galaxies, the spatial correlations of tensor fields, such as galaxy spins and shapes, are ones of promising sources that we can access in the era of large surveys in near future. The perturbation theory is a powerful tool to analytically describe the behaviors and evolutions of correlation statistics for a given cosmology. In this paper, we formulate a nonlinear perturbation theory of tensor fields in general, based on the existing formulation of integrated perturbation theory for the scalar-valued bias, generalizing it to include the tensor-valued bias. In order to take advantages of rotational symmetry, the formalism is constructed on the basis of irreducible decomposition of tensors, identifying physical variables which are invariant under the rotation of coordinates system. Fundamental formulations and calculational techniques, applications to some simple examples are presented.
Shohei Saga
Relativistic distortions in galaxy density-ellipticity correlations
We study relativistic effects, arising from the light propagation in an inhomogeneous universe. We particularly investigate the effects imprinted in a cross-correlation function between galaxy positions and intrinsic galaxy shapes (GI correlation). Considering the Doppler and gravitational redshift effects as major relativistic effects, we present an analytical model of the GI correlation function, from which we find that the relativistic effects induce non-vanishing odd multipole anisotropies. We particularly focus on the dipole anisotropy. Based on our model of the GI correlation, we estimate the detectability of the dipole signal.
Zvonimir Vlah (Invited)
EFT of galaxy shapes
I will give a short review of how to construct a systematic perturbative
description of galaxy shape statistics on large cosmological scales.
I will present the recent results and outline some of the possible future extensions.
Sandrine Codis (Invited)
Intrinsic alignments from cosmic web modeling
In this talk, I will describe theoretical works to try and understand and predict intrinsic alignments based on cosmic web analysis.
[9th December (Friday)]
Haoran Yu (Invited)
Baryonic Effects on Lagrangian Clustering and Angular Momentum Reconstruction
TBA
Takahiro Nishimichi
Dark Quest II project and halo shapes
N-body simulation is a standard tool to follow the gravitational dynamics of cosmological structure formation. Our simulation campaign called “Dark Quest” (DQ) is aimed at providing accurate theoretical templates of two point statistics of the matter density field and their tracers based on a large ensemble of cosmology-varying N-body simulations in light of recent joint lensing and clustering analyses of galaxies. This database was also used, as a by-product, for studies of intrinsic alignments (IAs) of halos both in Fourier and configuration space. We are now preparing new simulation and postprocessing tools for the second phase of the project, DQ2. In this talk, we briefly discuss the current status of the project, with a particular focus on the halo-shape related information yielded and stored from the project.
Khee-Gan Lee
Intrinsic Alignments Between Galaxies and the Cosmic Web at z~1-2 in the IlustrisTNG Simulations
Galaxy formation theories predict that galaxy shapes and angular momenta have intrinsic alignments (IA) with the cosmic web, which provides an observational test of various theories, and is important to quantify as a nuisance parameter for weak lensing. We study galaxy IA in the IllustrisTNG suite of magnetohydrodynamical simulations at redshifts 1 and 2, finding that alignment trends are consistent with previous studies. However, we find that the magnitude of the spin alignment signal is much weaker ($\gtrsim 2-5\times$) than seen in previous studies of the Horizon-AGN simulation, suggesting that IA may have significant dependence on subgrid physics. Based on IllustrisTNG, we then construct a mock observational spectroscopic survey that shape-cosmic web IA at $z\sim 1-2$, modeled on the upcoming Subaru Prime Focus Spectrograph Galaxy Evolution (PFS GE) survey. We find that accounting for previously-neglected variation on viewing angle onto the galaxy sample and cosmic web induces significant errors in observed alignment. We predict a $5.3\sigma$ detection of IlustrisTNG's shape IA signal at \zone{}, and although a detection would be challenging at \ztwo{}. This however suggests that PFS GE should be able to constrain the stronger signal expected from HorizonAGN.
Masahiro Takada
Closing