Conference Programme.



Cosmic Microwave Background: Current Status and next Challenges. Mathieu Remazeilles (IFCA). We will give a brief overview of the current state of CMB observations and their cosmological implications. We will then outline some of the key scientific goals of upcoming and future CMB experiments, with a focus on new CMB observables (CMB B-mode polarization, secondary CMB anisotropies, CMB spectral distortions), and underscore the new challenges to overcome in terms of foreground characterization and subtraction.

Scientific results with the QUIJOTE-MFI wide survey. Carlos H. López-Caraballo (IAC). The detailed understanding of the Galactic emission processes in the frequency range from 1 to 3000 GHz is crucial for a state-of-the-art characterization of the Cosmic Microwave Background (CMB) anisotropies both in intensity and polarization. The Q-U-I JOint TEnerife (QUIJOTE) experiment is one of the current observational efforts devoted to understanding the polarization of the CMB anisotropies and other physical processes that emit in microwaves in the frequency range 10-42GHz and at large angular scales (1 degree resolution). At these wavelengths, the Galactic emission is dominated by four mechanisms: synchrotron, free-free, thermal dust and Anomalous Microwave Emission (AME). In this context, the new QUIJOTE-MFI wide survey at 11, 13, 17 and 19GHz, covering approximately 29000 deg2 with polarisation sensitivities in the range of 35-40 microK/deg, is useful for pinning down the AME spectrum at low frequencies, allowing a more reliable separation between the AME and other components than in previous analyses. In this talk I will present a brief overview of the main scientific publications that constitute the MFI wide survey release, with emphasis on the latest AME results in different environments. Finally, I will also present the status of the QUIJOTE MFI2 instrument, an upgraded version of the former MFI instrument, that will be commissioned in the next months. The QUIJOTE-MFI wide survey maps are publicly available in the QUIJOTE collaboration webpage ( ).

The LiteBIRD space mission. Massimiliano Lattanzi (INFN Ferrara). LiteBIRD the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. In my talk, I will provide an overview of the LiteBIRD project and of the expected scientific achievements of the mission.

CMB Spectral Distortions Measurement Prospects. Xavier Coulon (IAS, Paris) . The COBE/FIRAS mission measured the Cosmic Microwave Background (CMB) spectrum and showed that its spectral energy distribution was close to a perfect blackbody with tiny departures of order ΔI/I≃10^-5. These are referred to as spectral distortions. The two main types of spectral distortions are the y-distortion from inverse Compton in the optically thin regime (z < 5x10^4), and the µ-distortion imprinted by energy released in the optically thick regime (z > 5x10^4). Measurements of these signals are challenging but allows us to access information about the full thermal history of the Universe that cannot be extracted in any other way. For this reason, high-precision spectroscopy of the CMB is one of the three themes that have been selected by the ESA Voyage 2050 programme. I will present an effort undertaken to define future missions and instruments dedicated to the measurement of the CMB spectral distortions. Optimizing both instrument concept and mission parameters can be achieved by combining outputs of two newly developed models. The first is a versatile photometric model of key instrument subsystem choices. The second is a sky emission model accounting for spatially varying foregrounds at frequencies relevant for CMB spectral distortions. I will present the tow models and their outputs in two cases, FOSSIL, a space mission proposed in answer to the recent ESA M7 proposal and BISOU, a study for a balloon-borne mission.

CMB LSS cross correlation review.  Giulio Fabbian (Cardiff University). I will review the science cases that can be probed using cross-correlation between CMB and LSS observables.

Bayesian inference of dust emissivity and reconstruction of CIB anisotropy. Debabrata Adak (IAC). Galactic dust emission is one of the significant foregrounds in measurements of CMB intensity and polarisation at frequencies above ~100 GHz. To mitigate this foreground contribution from the high frequency measurements, it is essential to understand how spectral properties of dust behamve across far-infrared frequencies. Understanding the Galactic dust emission is also critical for the reliable reconstruction of the Cosmic Infrared Background (CIB) anisotropies that is a tracer of large-scale structures. The fact that the CIB and the Galactic dust share similar spectral properties makes it crucial to understand the spatial and spectral distribution of Galactic dust to separate the two emissions reliably. In this talk I will discuss a new methodology to study dust and reconstruction of CIB at Planck frequencies.

Recovering the CMB in temperature and polarization with neural networks. José Manuel Casas (Universidad de  Oviedo). In this talk, we present a neural network for recovering the CMB in Planck realistic simulations in temperature ( and polarization ( patches of the sky. We train the network with a sky formed by the CMB, synchrotron, dust, PS, thermal SZ and instrumental noise. Once trained, the network is validated with data not used for training. We estimate the TT, EE and BB power spectra. In temperature, we reach a mean difference between input and recovered of 0+-100 muk2 up to l=4000. Residuals are two orders of magnitude bellow the input signal in the extragalactic region and one order of magnitude in the Galactic plane. Noise levels seem not affect the neural network to accurately perform at small scales. In polarization, after smoothing the sky, we accurately recover both E and B modes up to l=800. In particular, the E-mode is recovered with a difference between true and recovered CMB of 0.1+-0.3 muk2, while the B mode is recovered with a difference of 0.002+-0.02. Residuals are two orders of magnitude bellow the input E signal and one order of magnitude bellow the B one, although noise levels start to dominate the signal along the B-mode. Training without noise, as a prediction for future CMB experiments with higher polarization sensitivity than Planck, allows us to accurately recover the signal at l=1500. Training with a proper foreground model is crucial for recovering the B-mode.

CONCERTO: instrument and status. Alessandro Fasano (IAC). CONCERTO (CarbON CII line in post-rEionization and ReionizaTiOn) is a low-resolution Fourier transform spectrometer dedicated to the study of the star-forming galaxies and the cluster of galaxies in the transparent millimeter windows from the ground. It is characterized by a large instantaneous field-of-view of 18.6 arcmin, operates at 130–310 GHz, and was installed on the 12-meter Atacama Pathfinder Experiment (APEX) telescope at 5100 m above sea level. The CONCERTO double focal planes host two arrays of 2 152 kinetic inductance detectors and represent a pioneering instrument to challenge a state-of-the-art scientific case. This paper introduces the CONCERTO instrument and explains its status, shows the first CONCERTO spectral maps of Orion, and describes the perspectives of the project.f

Constraining CMB physical processes using Planck 2018 data. Miguel Ruiz Granda (IFCA). This paper aims to perform a phenomenological parametrisation of the standard cosmological model, ΛCDM, to weigh the different physical processes that define the pattern of the angular power spectra of the Cosmic Microwave Background (CMB) anisotropies. We use six phenomenological amplitudes to account for the Sachs-Wolfe, early and late Integrated Sachs-Wolfe, polarization contribution, Doppler and lensing effects. To do so, we have adapted the CLASS Boltzmann code and used the Markov Chain Monte Carlo (MCMC) sampler of Cobaya to explore the Planck 2018 likelihood (PR3) to constrain different combinations of cosmological and phenomenological parameters. In a previous work, the phenomenological amplitudes were constrained using only the TT data, however, by including the polarization and lensing data we find that the constraints on these physical contributions are tighter. In addition, some degeneracies that appear only when considering TT data are completely broken by taking into account all Planck 2018 data. Consequently, models with more than three phenomenological amplitudes can be studied, which is prohibitive when only the temperature power spectrum is used. The results presented in this paper show that the Planck experiment can constrain all phenomenological amplitudes except the late Integrated Sachs-Wolfe effect. No inconsistencies were found with the ΛCDM model, and the largest improvements were obtained for the models that include the lensing parameter, A_L.

Probing large-scale structure with line intensity mapping. Steve Cunnington (University of Manchester). Line intensity mapping surveys provide a radically different approach to probing large-scale cosmic structure than what is conventionally done with galaxy surveys. Instead of resolving and cataloguing the coordinates of billions of galaxies required to sufficiently sample large volumes, intensity mapping instead records the combined unresolved emission from all galaxies and builds a brightness map that correlates with the underlying dark matter field. By identifying a strong spectral feature to map, the redshifted signals can be gathered into a 3D survey over very large scales, with relatively short observation times. Purpose-built intensity mapping experiments have now arrived and are delivering promising results. I will summarise the intensity mapping landscape for most lines across the electromagnetic spectrum but will mainly focus on the 21cm feature at radio wavelengths from neutral hydrogen. Telescopes such as MeerKAT (a precursor to the Square Kilometre Array) are delivering vast amounts of 21cm intensity mapping data from which early constraints are already being delivered with the promise of more exciting science over the next few years.

Measuring primordial non-Gaussianity from the DESI LRGs and CMB lensing cross-correlation. José Bermejo-Climent (IAC). The cross-correlation between matter tracers and CMB fields encodes important and unique information. In particular, it has been reported the capability of the CMB lensing - galaxy clustering cross-correlation to constrain the primordial local non-Gaussianity fNL, due to its imprint on the galaxy bias scale dependence. We use the Planck 2018 lensing maps and Luminous Red Galaxies (LRG) from the DESI legacy imaging survey used to select spectroscopic DESI targets. To remove the systematics at large scales which could likely bias a fNL measurement, we apply to the LRG maps a neural network code for imaging systematics mitigation and test its performance with lognormal mocks. We find the LRG - CMB lensing cross-spectra are less sensitive to the systematics mitigation recipe than the LRG autospectra. At the parameters level, we can achieve a fNL uncertainty around ~30 from the LRG - Planck lensing cross-correlation and close to ~10 when adding the LRG autocorrelation too. Our results are an independent test on primordial non-Gaussianity and will be improved with the addition of further DESI tracers such as ELG and QSO. 

The anomaly of the CMB power with the latest Planck data. Matteo Billi (IFCA, INAF-OAS). The lack of power anomaly is an unexpected feature observed at large angular scales in the CMB maps by the COBE, WMAP and Planck satellites. This signature, which consists in a missing of power with respect to that predicted by the ΛCDM model, might hint at a new cosmological phase before the standard inflationary era. Here we investigate how CMB polarisation data improve the understanding of this feature. To this end, we apply to the latest Planck data, both PR3 (2018) and PR4 (2020) releases, a new class of estimators able to evaluate this anomaly considering temperature and polarisation data both separately and in a jointly way. This is the first time that the PR4 dataset is used to study this anomaly. Our analysis shows that the estimator based only on temperature data confirms the presence of a lack of power with a lower-tail-probability (LTP) equal or even lower than 0.33% and equal to 1.16%, for PR3 and PR4 respectively. To our knowledge the LTP <= 0.33% for the PR3 dataset is the lowest one present in the literature considering the Planck confidence mask. We find significant differences between these two datasets when just polarisation is taken into account. However, we also show that for the PR3 dataset the inclusion of the subdominant polarisation information provides estimates which are less likely accepted in a ΛCDM cosmological model than the only-temperature analysis on the whole harmonic-range considered.

A refined Planck thermal SZ Compton y-parameter all-sky map to probe the entire hot gas in the Universe. Jyothis Chandran (IFCA). In 2015, the Planck Collaboration released the first all-sky maps of the thermal Sunyaev-Zeldovich (SZ) Compton y-parameter, based on the Planck data release 2 (PR2). The Planck PR2 y-map played a crucial role in delving into the astrophysical properties of hot gas within and between galaxy clusters, while it also enabled us to obtain independent cosmological parameter constraints beyond those derived from primary CMB. Since then, the data quality has significantly improved with the latest Planck data release 4 (PR4). Using the Needlet Internal Linear Combination (NILC) method, we have derived a new all-sky map of the thermal SZ Compton y-parameter from the Planck PR4 frequency maps. I will present this refined data product, highlighting significant improvements in noise reduction and mitigation of residual foreground contamination when compared to the Planck PR2 y-maps. Furthermore, I will conduct a comparative analysis with other publicly available Compton y-maps.

Cosmology with the Euclid mission. Pablo Fosalba (ICE, CSIC-IEEC). ESA's Euclid satellite is a mission designed to obtain the most precise 3D map of the universe to date. Launched this last July, it is already observing the sky in the visible and near-IR with the goal of unveiling the nature of dark-matter and dark-energy that dominate the evolution of the universe. I will review what fundamental questions in cosmology it will address, and how we plan to optimally exploit its unprecedented high quality data.

The Uchuu-GLAM BOSS, eBOSS and DESI LRG lightcones: Exploring clustering and covariance errors. Julia Ferrer Ereza (IAA). In this talk, we explore clustering and covariance errors of BOSS, eBOSS and DESI surveys in configuration and Fourier space with a new generation of galaxy lightcones. We create 118 lightcones using the Uchuu simulation: a 2Gpc/h N-body simulation tracking 2.1 trillion dark matter particles within a Planck-LCDM cosmology. Simulation's (sub)halos are populated with Luminous red galaxies (LRG) using the subhalo abundance matching. For estimating covariance errors, we generate 6000 GLAM-Uchuu LRG lightcones based on GLAM N-body simulations. LRG are included using halo occupation distribution. Our simulated lightcones reproduce BOSS/eBOSS/DESI clustering statistics on scales from 0.08 to 150Mpc/h and redshifts 0.2 to 1.0, in configuration and Fourier space. We analyse stellar mass and redshift effects on clustering and bias, revealing consistency with data and noting an increasing bias factor with redshift. Our investigation leads us to the conclusion that the Planck-LCDM cosmology accurately explains the observed LSS. Furthermore, we compare our GLAM-Uchuu LRG lightcones with MD-Patchy and EZmock, identifying large deviations from observations within 4Mpc/h and higher data estimated errors. Lastly, we explore cosmology's impact on galaxy clustering. Our results suggest that, given the current level of uncertainties, we are unable to distinguish models with and without massive neutrino effects on LSS.

Evolution of cosmic filaments in the MTNG simulation. Daniela Galárraga-Espinosa (Max-Planck-Institute for Astrophysics). I will present a recent study of the evolution of cosmic filaments across redshift in the large MilleniumTNG hydro-dynamical simulation. In this study, I characterise for the first time the evolution of some important properties of cosmic filaments, such as their lengths, growth rates, radial density profiles, and their connection to the nodes of the web, from z=4 to z=0. By tracking the spatial evolution of individual filaments, I will demonstrate that filaments of different lengths follow different evolutionary paths. While short filaments preferentially contract, long filaments expand along their longitudinal direction with growth rates that are the highest in the early, matter dominated Universe. I will finally show that cosmic filaments can be used as additional probes for dark energy, but further theoretical work is still needed.

HYMALAIA: A Hybrid Lagrangian Model for Intrinsic Alignments. Francisco Germano Maion (DIPC). The intrinsic alignment of galaxies is an important ingredient for modelling weak-lensing measurements, and a potentially valuable cosmological and astrophysical signal. In this talk, I will present HYMALAIA: a new model to predict the intrinsic alignments of biased tracers. HYMALAIA is based on a perturbative expansion of the statistics of the Lagrangian shapes of objects, which is then advected to Eulerian space using the fully non-linear displacement field obtained from N-body simulations. We demonstrate that HYMALAIA is capable of consistently describing monopole and quadrupole of halo shape-shape and matter-shape correlators, and that, without increasing the number of free parameters, it does so more accurately than other perturbatively inspired models such as the non-linear alignment (NLA) model and the tidal-alignment-tidal-torquing (TATT) model.

Halo secondary bias through cosmic time. Andrés Balaguera (IAC). Based on a large cosmological simulation (UnitSim) we explore the halo secondary (or assembly) through cosmic history (from z=6 to z=0). To do that, we introduce new environmental properties at the halo level and perform a principal component analysis aiming at identifying the main halo property (or properties) as a function of time. We assess the signal of secondary bias, both in real and redshift space. We assess the clustering of individual halo properties through the marked statistics. We characterize the distribution of halo bias in terms of a number of intrinsic and environmental halo properties and identify applications for the generation of halo mock catalogs.

Lyman-alpha cosmology embraces the nonlinear regime. Jonás Cháves-Montero (IFAE). The Lyman-alpha forest provides a unique window into the high-redshift universe, offering exceptional sensitivity to various ΛCDM extensions such as the sum of neutrino masses, the running of the spectral index, and the nature of dark matter. However, harnessing the full potential of Lyman-alpha measurements is a formidable challenge due to the nonlinear nature of gravity and its dependence on the thermal and ionization state of the intergalactic medium. In this presentation, I will outline our efforts to prepare for the optimal utilization of Lyman-alpha data from the Dark Energy Spectroscopic Instrument (DESI) survey. We are developing a series of surrogate models, commonly referred to as emulators, to expedite predictions for this observable. I will begin by explaining our methodology for constructing an emulator for the one-dimensional power spectrum of the Lyman-alpha forest. Subsequently, I will delve into our ongoing work in creating the first emulator for its three-dimensional power spectrum. These emulators will play a pivotal role in the cosmological analysis of Lyman-alpha measurements from DESI.

Cosmology combining weak lensing surveys. Anna Porredon (Ruhr-Universität Bochum). Weak gravitational lensing of background galaxies is a powerful probe of the growth of structure and the expansion of the Universe. I will review the cosmological results from current weak lensing surveys, such as the Dark Energy Survey (DES) and the Kilo-Degree Survey (KiDS), and present results from their recent combined cosmological analysis of cosmic shear. Last, I will discuss plans for upcoming cosmological analyses combining weak lensing data from multiple surveys.

Early Data Release of the Dark Energy Spectroscopic Instrument Survey. Aurelio Carnero Rosell (IAC). In june 2023, the Dark Energy Spectroscopic Instrument (DESI) survey released its first public release, the EDR. It includes spectra and redshifts for 1.2 million galaxies and 500,000 stars from the Milly Way. In just one year of operations surppassed its predecesor eBOSS (~1 million galaxies), confirming its top-level design. The high level of precision of DESI will set new standards in the study of the large scale structure of the Universe. In this talk I review the content and main results from EDR, including the first BAO detections. I will explain some of the techniques used for ameliorating systematic effects, and introduce the effort to generate realistic galaxy mocks both for covariance matrices and for systematic effects studies. Finally, I will update about the current status of analysis and observations.

Mocking the Large Scale Structure in the Universe. Francisco-Shu Kitaura (IAC). I report on the COSMIC SIGNAL project, which aims to provide extensive mock catalogues that capture cosmic evolution for all tracers of the large-scale structure, spanning the redshift range 0 < z < 3.8. We introduce the cosmic WEB evolutiON code (Kitaura+21, 23) which computes the dark matter distribution and its dynamics on the lightcone based on Lagrangian perturbative expansions including ultraviolet regularisations extended to an Eulerian framework, also accounting for general relativistic screening effects. Subsequently, these lightcones are populated with tracer number counts, representing various astrophysical objects such as BGs, eLGs, LRGs, QSOs, and Ly-a fluxes. We rely on a novel hierarchical cosmic web classification to model nonlocal bias (Coloma-Nadal, Kitaura+ip; Kitaura+22), and the application of a subgrid model that reconstructs tracer positions within voxels. This process leverages a novel perturbed (e)ALPT technique, which identifies density peaks within the dark matter field and collapses toward them to faithfully reproduce the clustering of the galaxies (Forero-Sánchez, Kitaura+ip). Peculiar velocities are assigned, incorporating both coherent velocities derived from (e)ALPT and a dispersed velocity component calibrated to match the characteristics of the reference catalogues. To generate reference catalogues from a few, we have a novel passive evolution mapping technique incorporating evolution and selection (Tang, Kitaura+ip).

Modelling the distribution of galaxy multi-tracers through cosmic time. Ginevra Favole (IAC). In the Universe we observe different galaxy populations (LRG: luminous red galaxies; ELG: emission line galaxies; QSO: quasars) that act as biased tracers of the same underlying dark matter field. By combining several tracers over wide cosmological volumes, and making use of the fast/accurate mocking techniques developed in the framework of the COSMIC SIGNAL project at IAC/ULL, we are able to precisely model the galaxy clustering and weak lensing probes to then constrain the growth of structure and the Universe expansion history with percent precision. Past surveys, such as SDSS-III/BOSS, mostly targeted highly complete samples of LRG at low redshift (z<0.7), which are relatively easy to model. More recently, SDSS-IV/eBOSS opened the path to multi-tracer surveys by observing ELG and QSO out to z=2. The ongoing and next generation of cosmological surveys, such as DESI, Euclid, 4MOST or LSST, will observe different populations of galaxies out to high redshift, most of them very incomplete in luminosity or stellar mass. In this talk I will briefly revise the most effective techniques used to connect galaxy multi-tracers, with different levels of completeness, to their host dark matter haloes and I will show my latest results using DESI data.

The status of cosmic tensions in 2023. Vivian Poulin (LUPM, Université de Montpellier). I will review the state of cosmic tensions, focusing particularly on the Hubble and ''sigma8'' (the amplitude of fluctuations) tensions. After a brief discussion of the current experimental status and systematic/modeling errors, I will discuss attempts at resolving tensions, with a particular focus on what these tensions could indicate regarding the properties of dark matter and/or dark energy. I will conclude with guidelines towards building a new "concordance cosmology". 

Cosmic magnification bias with submillimeter galaxies. Marcos M. Cueli (SISSA). In recent years, the galaxy-mass cross-correlation has predominantly been probed within weak gravitational lensing via the correlation between foreground positions and background galaxy ellipticities. However, the cross-correlation between the positions of background and foreground galaxies is an alternative observable which, up to now, has been largely overlooked. The corresponding signal is a manifestation of the gravitational lensing effect of magnification bias and has been shown to become extremely significant when using a background sample of submillimeter galaxies. In this talk, I will discuss how this submillimeter galaxy magnification bias can be effectively exploited as a cosmological probe and present a series of results from our recent work on this matter.

Redshift space distortion model comparison: fully against partially perturbative models. Benjamín Camacho Quevedo (IEEC-CSIC). The large-scale structure of the universe is a crucial source of cosmological information at low redshift. Over the next decade, Stage IV surveys such as the Dark Energy Spectroscopic Instrument (DESI) and Euclid will significantly enhance the quality of observational constraints by collecting millions of galaxy redshift samples. These surveys will cover a cosmic volume much larger than previous experiments, requiring a corresponding refinement of the theoretical models employed for data analysis to ensure the avoidance of systematic effects that could impact data interpretation. In this study, we compare two recent developed methods used for extracting information from the full-shape analysis of galaxy power spectrum multipoles. The first method, the Effective Field Theory of Large Scale Structure (EFTofLSS), constructs theoretical predictions by fully perturbing around the density and velocity fields. The second method keeps the velocity difference generating function (VDG) non-perturbative and represents it in a functional form. We provide a concise overview of the models, highlighting their main differences, performance, scales of validity, and potential limitations.

Consistent clustering and lensing of SDSS-III BOSS galaxies with an extended abundance matching formalism. Sergio Contreras (DIPC). Several analyses have shown that ΛCDM-based models cannot jointly describe the galaxy clustering (GC) and galaxy-galaxy lensing (GGL), which is commonly known as the 'lensing-is-low problem'. In this talk, I will show that an extension of Subhalo Abundance Matching, dubbed SHAMe, successfully solves this problem. First, we show that this model accurately reproduces the GC and GGL of a mock galaxy sample in the TNG300 hydrodynamic simulation with properties analogous to those of BOSS galaxies. Then, we switch our attention to observed BOSS galaxies, and we attempt to reproduce their GC and GGL by evaluating SHAMe on two different simulations: one adopting a Planck cosmology, and the other adopting a "Low S8" cosmology. We find excellent agreement between SHAMe predictions and observations for both cosmologies, indicating that the lensing-is-low problem originates from approximations in previous theoretical descriptions of the data. The main difference between SHAMe results in these cosmologies is the level of galaxy assembly bias, which is approximately 20 percent and 10 percent for Planck and Low S8, respectively. These results highlight the dangers of employing oversimplified models to analyse current large-scale structure data sets and the need for realistic yet flexible descriptions of the galaxy-halo connection.

ARRAKIHS: The New ESA F-Class Mission to Investigate the Nature of Dark Matter. Rafael Guzmán (IFCA). The “Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys” (ARRAKIHS) mission will explore the ultra-low surface brightness universe to investigate the nature of Dark Matter. ARRAKIHS was selected in November 2022 as the next F-class mission at ESA for Phases 0/A/B, with an estimated launch date in 2030. The ARRAKIHS science consortium, led by IFCA (Spain) in partnership with several European research centers and space companies, is collaborating with ESA to launch an array of visible and infrared cameras on board a mini-satellite in Low Earth Orbit. The goal of ARRAKIHS is to test the predictions of different Dark Matter models and baryon physics mechanisms on the halo structure as well as on the statistics of halo satellites and stellar streams for a representative sample of MW-type galaxies in the nearby Universe. In this talk, I will provide an update on the mission baseline concept of ARRAKIHS after successfully passing the Mission Definition Review last September. 

Multi-scale emulation of the non linear clustering of galaxies. Tyann Dumerchat and Julian Bautista (CPPM Aix-Marseille Université). While future and ongoing galaxy surveys like the Dark Energy Spectroscopic Instrument (DESI) span deeper and wider fields of view with a better precision, bringing more and more statistics, our observables error-bars shrink, setting some limits on the validity range of our perturbative models. One popular solution to access the relevant information at small scales is to train a simulation based model from a suite of N-body simulation. We present a new Gaussian process model allowing to extend the input parameter space dimensions and to use non diagonal correlated noise. Unlike with the standard method, where an emulator is trained over the cosmological and galaxy-halo connection parameters independently for each scales, we are able to interpolate and use the correlations between scales. As a proof of concept, we use our new framework to build an emulator for the non linear clustering of galaxies in redshift space from the AbacusSummit N-body simulations at redshift z = 0.2.

Mapping modified gravity signatures with cosmic volumes. Jorge Enrique García-Farieta (IAC). The new generation of galaxy surveys will provide unprecedented data allowing us to test gravity at cosmological scales. A robust cosmological analysis of the large-scale structure demands exploiting the nonlinear information encoded in the cosmic web. This study delves into the meticulous task of mapping modified gravity (MG) signatures within cosmic volumes by employing a large state-of-the-art particle mesh N-body simulations including modified gravity models. On the one hand, we model the effective nonlinear and nonlocal bias between a tracer distribution of MG with respect to a dark matter field obtained by assuming the Lambda Cold Matter (LCDM) scenario. This technique provides fast calculation of MG mock catalogs using a small number of reference simulations. On the other hand, we implement Bayesian neural networks with enriched approximate posterior distributions for estimating cosmological parameters with uncertainty estimations. This approach contributes to setting the path to extracting cosmological parameters from complete small cosmic volumes towards the highly nonlinear regime.

2D tomographic analysis of J-PLUS DR3 high odds galaxies. Carlos Hernández-Monteagudo (IAC). We present a thorough tomographic study of the density (ADF) and redshift angular fluctuations (ARF) of a high-odds (odds>0.8) galaxy subsample identified in the ~3,000 sq.deg of the Data Release 3 of the J-PLUS survey. After correcting for systematics modulating the observed galaxy density (like stars, photometric depth or extinction), we interpret, on scales larger than 5 Mpc/h, the angular power spectra of ADF and ARF in the context of the linear perturbation theory from z~0.05 up to z~0.25. Given the non-linear character of the scales being sampled, the bias values recovered by the ADF and ARF do not match exactly, although in both cases are close to unity and increase with redshift. Non-linear power in the ADF seem to bias high the contribution from the term triggered by radial peculiar velocities, an effect that is not seen for the ARF, for which such term remains compatible with zero given the photo-z uncertainties. The ARF, on the other hand, provide an independent measurement of the photo-z errors (sigma_{Err,z} ~ 0.015), which is close but slightly higher than estimates from the LePhare photo-z code (sigma_{Err,z} ~ 0.0105). When cross-correlating J-PLUS ADF shells to CMB lensing convergence from Planck, we find weak cross-correlation evidence that (mildly) tend to decrease ADF bias estimates. We expect this same pipeline to provide more insightful cosmological constraints as the J-PAS survey keeps gathering deeper galaxy/QSO catalogs.

Cosmology with voids: DES, Pan-STARRS, and Gaia results. András Kovacs (Konkoly Observatory). The gravitational lensing signal of large-scale structures probes the growth of structure in the low-redshift cosmic web. In this talk, I summarise the results on detecting cosmic voids in the distribution of luminous red galaxies from the Dark Energy Survey Year-3 data set, and the analyses of their cross-correlations with lensing convergence maps. Then, I will present new results from the analysis of the Pan-STARRS LRG catalog that has about 3 times the area of the DES Year-3 footprint, as well as preliminary results from the Gaia QSO data set and the high-z voids that are detectable I the spare distribution of quasars. I will explain why these lensing signals from the largest cosmic structures are intertwined with cosmological anomalies that have raised a lot of eyebrows in the last few years. 

Neutrino cosmology. Martina Gerbino (INFN Ferrara). The intersection of the cosmic and neutrino frontiers is a rich field where much discovery space still remains. Cosmology is an independent window to the physics of light relics – active neutrinos and other light massive particles that may populate the cosmological plasma - and allows to probe their behaviour over cosmological times and scales, something unachievable via terrestrial laboratory searches. In this talk I will discuss how observations of the cosmic microwave background and the large-scale structure of the Universe can be used to constrain the properties of neutrinos and other light relics. I will focus on "new physics" scenarios (e.g. beyond-standard-model properties, axion-like particles....). I will further discuss detection prospects from forthcoming cosmological observations.

Cosmology from a simulated neutral hydrogen full sky. Jacobo Asorey Barreiro (CIEMAT). We are currently living a fruitful era of cosmology from wide field optical cosmological surveys. By analyzing the clustering of matter, we can use the growth of structure to understand dark energy or to test different models of gravity. We plan to use intensity mapping as a low resolution spectroscopic technique in which we use the intensity given by the emission from neutral hydrogen lines from patches of the sky, at different redshifts, with surveys such as Tianlai or CHIME and SKA in the future. I will introduce the simulated neutral hydrogen full sky catalogues that we have created (HIR4), using the Horizon run 4 simulations. In particular, I will show the prospects of measuring the growth rate of structures with only intensity mapping information from surveys such as Tianlai around redshift z=1 and the prospects of cross-correlating the intensity mapping information with optical galaxy catalogues, such as DESI, especially regarding BAO measurements.

Weak lensing on small scales. Constance Mahony (DIPC). The modelling of non-linear scales has been identified as a possible source of the current tension between early (CMB) and late time (weak lensing and galaxy clustering) measurements. On large scales there is a linear relationship between galaxies and the underlying distribution of dark matter, but on small scales more complex modelling is required due to the impact of non-linear galaxy scale astrophysics. A key technique for including non-linear scales is the halo model. However, current halo modelling contains assumptions which are no longer valid due to advances in observational precision. I will present the results of the most recent small scale Kilo Degree Survey analysis (Dvornik et al. 2022), which utilises an improved version of the halo model (Mahony et al. 2022b). I will then discuss the halo model for intrinsic alignments (Fortuna et al. 2021), which enables all three weak lensing and galaxy clustering correlations to be modelled consistently on small scales.

Photometric redshifts in the PAUS wide fields. David Navarro Gironés (ICE-CSIC). Galaxy redshifts are essential to characterize the large scale structure of the Universe but are challenging to obtain for magnitude limited samples of galaxies, particularly at high redshift and/or faint luminosities.In this talk I will present photometric redshifts estimations in the wide fields of the Physics of the Accelerating Universe Survey (PAUS). PAUS wide fields cover ~50 deg2, with a redshift range of 0<z<2. PAUS uses narrow band photometry with 40 filters in the range 4500 Angstroms and 8500 Angstroms, to achieve photometric redshift accuracies equivalent to low resolution spectroscopy, for ~1.8 million galaxies up to i-magnitude < 23. We estimate redshifts with an SED template-fitting code, with a novel modification in the calibration technique of the zero-point between broad and narrow bands. By defining δ = (zb-zs)/(1+zs), where zb and zs are the photometric and spectroscopic redshifts, we obtain a σ68 of δ ~ (0.003,  0.06) for i-magnitude ~(19, 23). PAUS wide fields overlap with weak lensing fields from CFHTLenS and KiDS/GAMA, therefore the combination of accurate redshifts and shear measurements will enable a unique opportunity to study galaxy clustering and weak lensing, including galaxy intrinsic alignments.

The Gravitational Wave Background: Evidence and Interpretations. Andrea Mitridate (DESY). By tracking the arrival times of radio pulses from a collection of pulsars in the Milky Way, several pulsar timing array collaborations have found evidence for a background of gravitational waves permeating our galaxy. In this talk, I will present this evidence and discuss possible astrophysical and cosmological interpretations of this gravitational wave background.

Stellar structures and their disputable role in galaxy evolution. Adriana de Lorenzo-Cáceres (IAC). Galaxies observed today are shaped by a number of stellar structures, namely ellipsoids, bulges, discs, multiple discs, bars, nested bars, rings, etc. Some of these structures are thought to be key in determining the future evolution of their hosts, like the paradigmatic case of stellar bars and their fundamental role in secular processes. While the Lambda Cold Dark Matter scenario provides an answer to when these structures form and therefore when the structure-driven evolution starts, recent observational results with JWST and Gaia are challenging such predictions. In this talk I will introduce the most relevant stellar structures for galaxy formation and evolution, as well as the current status of what we know and what we do not know anymore about their assembly in cosmic history.

Hyper Suprime-Cam 3x2pt analysis in harmonic space as precursor of the LSST. David Sánchez-Cid (CIEMAT). We perform a harmonic space joint analysis of galaxy clustering and weak lensing, the so-called $3 \times 2$pt analysis. We focus on the study of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) public data. HSC is the deepest Stage III survey and uses a prototype version of the Rubin Science Pipelines, making this dataset ideal to use as a precursor to the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). These characteristics allow us to put to the test software and tools developed by the LSST-DESC collaboration as well as setting constraints on LambdaCDM cosmological parameters. In this analysis we explore the applicability of mode deprojection as a method to correct the impact of observing conditions in spin-2 fields. As our main result, we present preliminary results in the plane Omega_m - S_8.

Quaia: A new quasar catalog for large-scale structure. Kate Storey-Fisher (DIPC). We present a new, all-sky quasar catalog, Quaia, that samples the largest comoving volume and has the cleanest selection function of any existing spectroscopic quasar sample. Drawing on the 6.6 million quasar candidates identified by the Gaia, which include low-resolution redshift estimates, and combining these with unWISE infrared data, we construct a catalog useful for cosmological quasar studies. We describe our work to decontaminate the sample, improve the redshift estimation, and model the selection function, resulting in a catalog with 1.3 million sources. We demonstrate the potential of Quaia to deliver competitive and complementary cosmological constraints, including on the parameters S8 and f_NL from cross-correlations with CMB lensing.

Studying large-scale structure tracers with machine learning. Natália Villa Nova Rodriguez (University of São Paulo). Understanding the relationship between the distribution of dark matter and its tracers, such as halos, galaxies and quasars, is a fundamental step towards extracting cosmological information from the large-scale structure of the Universe and also to elucidate the formation and evolution of galaxies. This is, however, a challenging task that involves several complex correlations. I will discuss the application of machine learning techniques to study the relation between the properties of galaxies, halos, and the distribution of dark matter. I may also briefly comment on quasar classification with machine learning in narrow-band photometric surveys (such as J-PAS and S-PLUS).

The first eROSITA All-Sky Survey : Constraining deviations from general relativity & f (R) gravity with cluster abundance. Emanuel Artis (Max Planck institute for extraterrestrial physics). The evolution of the cluster mass function traces the growth of the linear density perturbations and can be utilised for constraining the parameters of the standard model of structure formation and alternative gravity models. We present new constraints on the Hu-Sawicki parameterization of the f(R) gravity and deviations from general relativity using the growth rate of structures obtained with the first SRG/eROSITA All-Sky Survey cluster catalog in the Western Galactic Hemisphere in combination with the overlapping Dark Energy Survey Year-3, KiloDegree Survey and Hyper Supreme Camera data for weak lensing mass calibration. We find a strict upper limit tighter than the limits in the literature utilising cluster counts and highlights the difficulty for this model to reproduce observations. We then explore departures from general relativity using the cosmic linear growth index. Exploiting the statistical constraining power of the largest intra-cluster medium selected cluster sample to date, our data suggest a damping of structure formation at low z, as for other large scale structure probes. 

Fuzzy dark matter confronts rotation curves of nearby dwarf irregular galaxies. Andrés Bañares Hernández (IAC). The Fuzzy Dark Matter (FDM) model predicts that dark matter is composed of ultralight scalar field particles which possess macroscopic de Broglie wavelengths in the kpc scale. The wave behaviour of FDM erases structure formation on small scales and leads to the formation of galactic cores or solitons. This has been a subject of great interest in addressing challenges of the ΛCDM model, where simulations have been found to overpredict the number of observed satellite galaxies and generically predict cuspy density profiles, in tension with observations. We test FDM against a set of high-quality rotation curves from a robust sample of nearby isolated dwarf galaxies in the LITTLE THINGS survey, probing whether it can resolve these issues. We also examine the effects of baryonic physics and test against a number of astrophysical scaling relations predicted by the model, as well as the stellar-to-halo and concentration mass relations. We find that fits of cored density profiles show close agreement with the rotation-curve data, but that the particle masses needed to form those cores lead to a much too strong suppression in halo formation to account for observations and are in tension with an independent lower bound on the particle mass. Lastly, we find that that the scaling relations predicted by the model are significantly disfavoured by the data. Our conclusion is that the cores observed in this sample of dwarf galaxies are not consistent with the solitons predicted by FDM.

Combining dark and spectral sirens to infer cosmological parameters from gravitational waves data. Matteo Tagliazucchi (Univeristy of Bologna). Gravitational Waves (GWs) from merging compact binaries emerged as a new independent cosmological probe to study cosmic expansion history through the distance-redshift relation once the degeneracy between the binary redshift and chirp mass is broken. Different methods have been proposed to include in the inference process redshift information, from the direct detection of the electromagnetic counterpart (“bright sirens”), to statistically determine the merger host using a galaxy catalog (“dark sirens”), to using astrophysical properties of the GW population (e.g. the binary black holes mass distribution) to indirectly infer information about the redshift distribution of the population (“spectral sirens”). In this talk, I will present a new approach that combines “spectral” and “dark sirens” methods within a Hierarchical Bayesian framework to fully exploit multi-messenger information and constrain both cosmological and GW population parameters. We implemented this method in the forthcoming public code CHIMERA and tested on a set of simulated O4 and O5 GW events we developed and galaxy catalog to assess its improvements over previous approaches. I will discuss the results obtained, focusing on the importance of an accurate galaxy catalog and providing new forecast on the precision of the Hubble constant measurement, demonstrating that such method can achieve a few percent error in H0 using O(100) well-localized GW events while correctly marginalizing over population parameters.

Galaxy Classification with Neural Networks. Laura Toribio San Cipriano (CIEMAT). Classification of galaxies by type is fundamental to understanding the evolution of galaxies and the Universe. While morphological properties can be used to classify objects in the local Universe, the large volume of objects in cosmological surveys, as well as high redshift values, necessitate the use of innovative techniques.In this study, we present preliminary results from the separation of 12,113 galaxies using photometric data and a neural network algorithm. The observations correspond to a galaxy sample in the COSMOS field. Our classification categorizes galaxies into three groups: red, green and blue. In regards to red and blue galaxies, we achieve an accuracy rate exceeding 90%, while in regards to the third category of galaxies, we achieve an accuracy rate of approximately 64%. Furthermore, we are investigating which characteristics are most representative of those used by the neural network to classify galaxies with the help of the neural network. The computational effort has been supported by the CMS Analysis Facility infrastructure at CIEMAT.


Posters are available here.

Measuring the CMB spectrum over a large range of frequencies. Apolline Chappard (IAS). The QUIJOTE (Q-U-I JOint TEnerife) experiment is located at the Teide Observatory, at an 2,400 m altitude, in Tenerife, Canary Islands, a site with excellent observing conditions for microwave observations and with a long tradition in CMB research. In order to improve the quality of the QUIJOTE data, one needs to subtract the atmospheric signal. A way of identifying the atmospheric signal is with the cross correlation function. We will present the preliminary results of this analysis. 

Commissioning results from the QUIJOTE Thirty and Forty Gigahertz Instrument. Mateo Fernández-Torreiro (IAC). In this talk, I will briefly present the commissioning results from the second QUIJOTE instrument, the Thirty-and-Forty Gigahertz instrument. After a first test run in 2019, its commissioning phase lasted from November 2021 to October 2022. During this phase, the instrument observed the sky with 7 (4 at 30 GHz and 3 at 40 GHz) of the expected 29 horns to be installed at its focal plane. First characterization of beams returns full width (FWHM) estimates consistent with those expected, with 22 and 18 arcminutes values for 30 and 40 GHz horns. Preliminary gain calibration models using Tau A and Cas A data are presented, with calibration uncertainties at the 10% level. Polarization efficiencies are computed on Tau A data, showing that TGI pixels return consistent values with those expected (Π~6-7%). Finally, I will describe the achieved sensitivities during this phase using two science verification cases, Cygnus region and W44. For the latter, the polarization sensitivities per horn return 8-10 μK deg-1 values, already close to WMAP level (~7 μK deg-1). Projecting this performance to longer integration times and field sizes, the expected instrument performance is in line to fulfill its design goals (1 μK/deg sensitivity in one year timescale on cosmological fields with sizes 1200-1300 deg2). 

Inpainting CMB polarization maps with a Gaussian Constrained Realization approach. Christian Gimeno Amo (IFCA). The presence of astrophysical emissions in microwave observations forces us to perform component separation to extract the Cosmic Microwave Background (CMB) signal. However, even in the most optimistic cases, there are still strongly contaminated regions, such as the Galactic plane or those with emission from extragalactic point sources, which require the use of a mask. Since many CMB analyses, especially the ones working in harmonic space, need the whole sky map, it is crucial to develop a reliable inpainting algorithm that replace the values of the excluded pixels by others statistically compatible with the rest of the sky. This is especially important when working with Q and U sky maps in order to obtain E- and B-modes maps which are free from EB leakage. In this work we study a method based on Gaussian Constrained Realizations (GCR), already discussed in the literature for temperature, and extend it to polarization. Several test have been performed to asses the validation of the method, including the study of the one-dimensional probability distribution function (pdf), E- and B-mode map reconstruction, and power spectra estimation. Our results are promising, and even if we are limited to low resolution maps (Nside = 64 if TQU are considered) due to computational constraints, we believe that this will be a useful algorithm to be applied to future missions such as LiteBIRD, where the target are the largest scales.

Extremely magnified stars in MACS 0416. Prospects on constraining DM and stellar populations at high redshift. José María Palencia (IFCA). Caustic crossing events, occurring near the critical curves (CCs) of galaxy clusters, magnify individual stars by thousands, making them observable with IR/Optical telescopes. This phenomenon provides a unique opportunity to investigate compact dark matter within galaxy clusters. By leveraging these magnified stars, we can determine the surface mass density of dark matter near the CCs. Additionally, an extended dataset, achieved through more detection epochs and longer exposure times on single arcs, allows us to compile a comprehensive census of massive, bright stars in these galaxies. This helps us constrain the high-mass end of the Initial Mass Function (IMF) for galaxies at high redshift. Our focus will be on MACS 0416, an exceptional candidate with a dozen transient events, two arcs at redshift ~1 intersecting a CC, and we will present forecasts regarding the number of expected events.

Exploration of Early Universe Magnetogenesis via Biermann Battery with Laboratory Astrophysics and FLASH Simulations. Tristan Bachmann (University of Rochester). Magnetic fields are pervasive on cosmological and galactic scales, and understanding their formation and evolution is essential to our understanding of modern cosmology. One of the predominant proposed mechanisms for the origin of these fields is via the thermoelectric Biermann battery effect, which describes the spontaneous generation of magnetic fields due to non-parallel density and temperature gradients in plasmas. Though the effect is difficult to observe directly in the intergalactic medium due to its relatively small magnitude and the large spatial scales along which measurements are made, rapid growth in the field of laboratory astrophysics in recent decades now allows us to use scaling relations to investigate these phenomena on laboratory scales. Using FLASH, a high performance radiation-hydrodynamics code with extended magentohydrodynamic terms, we collaborate with experimentalists at UCLA to model the generation of Biermann-driven fields in such a laboratory setting, using high repetition rate laser produced plasmas at a frequency of ~1 Hz. We validate the FLASH code at new spatiotemporal regimes, and use these newly validated capabilities to assist in the modeling and design of continuing laboratory astrophysics experiments which will introduce a Nitrogen fill to the target chamber in order to facilitate shocks in the system, and to perform large scale simulations investigating the generation and subsequent amplification of seed fields and their impact on LSS. 

A method for calculating the parameters of the orbits of close binary supermassive black holes. A.E. Volvach, L.N. Volvach and M.G. Larionov (Crimea Radio Astronomy Laboratory). The data of harmonic analysis in the radio and optical ranges corresponded to each other, which made it possible to perform the necessary studies of objects based only on radio data when the optical counterparts of the AGN were not visible. This made it possible to significantly expand the range of sources under study. A model is proposed for finding the parameters of close binary systems (CBSs) from supermassive black holes (SMBHs), including a harmonic analysis of observational data series obtained in the optical and radio ranges. Regarding the example of the blazar 3C 273, the following parameters were obtained: the masses of the companions; their orbital characteristics, such as the speeds of movement in orbits; the reserves of the kinetic energy of the system; and others. It was found that AGN 3C 273 can be a very massive binary system at the stage of evolution close to merging. According to the obtained physical characteristics, 3C 273 is the most promising source for determining the gravitational waves coming from it using International Pulsar Timing Array gravitational wave detectors. This work was funded by the RSF, project number 23-22-10032.

Cardinal simulation to support the DES Legacy analyses. Nicola Deiosso (CIEMAT). Cardinal is a state-of-art N-body simulation covering a wide range of redshift up to 2.35, and outstanding in depth of m_r = 27. This simulation provides with a large variety of galaxy properties and realistic survey effects. Mock catalogs derived from the simulation play a key role for the validation of multi-probe analysis of ongoing and future galaxy surveys, such as DES and Rubin LSST-DESC. For the DES, we have checked that Cardinal simulation reproduces the physical properties of the DES (Y6 and Y3) Gold catalog and its derived data products. This poster will present the results of these robustness checks. This validation of the photometric DES dataset is crucial to obtain the Legacy cosmology result.