Sergio Contreras

Donostia International Physics Center

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Raúl E. Angulo

Donostia International Physics Center

Matteo Zennaro

University of Oxford

Nelson Padilla

Instituto de Astronomía Teórica y Experimental

Giovanni Aricò

University of Zurich

Idit Zehavi

Case Western Reserve University

Marcos Pellejero-Ibáñez

University of Edinburgh

C. M. Baugh

Durham University

Eugenio E. Vogel

Universidad de La Frontera

Jonás Chaves-Montero

Institute for High Energy Physics

P. Norberg

Fermi National Accelerator Laboratory

Cooperative Institutions

Durham University

Max Planck Institute for Astrophysics

Pontificia Universidad Católica de Chile

Donostia International Physics Center

Centre National de la Recherche Scientifique

Universidad Autónoma de Madrid

Consejo Nacional de Investigaciones Científicas y Técnicas

Max Planck Society

Indiana Cancer Consortium

ARC Centre of Excellence for All-sky Astrophysics

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Non-universality of the mass function: dependence on the growth rate and power spectrum shape

Monthly Notices of the Royal Astronomical Society (2021)

Lurdes Ondaro-Mallea Raúl E. Angulo Matteo Zennaro Sergio Contreras Giovanni Aricò

The abundance of dark matter haloes is one of the key probes of the growth of structure and expansion history of the Universe. Theoretical predictions for this quantity usually assume that, when expressed in a certain form, it depends only on the mass variance of the linear density field. However, cosmological simulations have revealed that this assumption breaks, leading to 10-20% systematic effects. In this paper we employ a specially-designed suite of simulations to further investigate this problem. Specifically, we carry out cosmological N-body simulations where we systematically vary growth history at a fixed linear density field, or vary the power spectrum shape at a fixed growth history. We show that the halo mass function generically depends on these quantities, thus showing a clear signal of non-universality. Most of this effect can be traced back to the way in which the same linear fluctuation grows differently into the nonlinear regime depending on details of its assembly history. With these results, we propose a parameterization with explicit dependence on the linear growth rate and power spectrum shape. Using an independent suite of simulations, we show that this fitting function accurately captures the mass function of haloes over cosmologies spanning a vast parameter space, including massive neutrinos and dynamical dark energy. Finally, we employ this tool to improve the accuracy of so-called cosmology-rescaling methods and show they can deliver 2% accurate predictions for the halo mass function over the whole range of currently viable cosmologies.

Halo mass function

Matter power spectrum

10.1093/mnras/stab3337

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Citations (27)

Site order parameter pg in ±J Ising square lattices

Revista Mexicana de Física (1998)

Sergio Contreras Morales Osorio Eugenio E. Vogel

Square (algebra)

Square lattice

Source

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Citations (0)

Percolation in ±J Ising lattices after removing frustration

Physica A Statistical Mechanics and its Applications (1998)

Eugenio E. Vogel Sergio Contreras F. Nieto A. J. Ramírez-Pastor

Percolation (cognitive psychology)

Square lattice

Lattice (music)

10.1016/s0378-4371(98)00144-7

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Citations (6)

DES Y3 cosmic shear down to small scales: constraints on cosmology and baryons

arXiv (Cornell University) (2023)

Giovanni Aricò Raúl E. Angulo Matteo Zennaro Sergio Contreras Angela Chen

We present the first analysis of cosmic shear measured in DES Y3 that employs the entire range of angular scales in the data. To achieve this, we build upon recent advances in the theoretical modelling of weak lensing provided by a combination of $N$-body simulations, physical models of baryonic processes, and neural networks. Specifically, we use BACCOemu to model the linear and nonlinear matter power spectrum including baryonic physics, allowing us to robustly exploit scales smaller than those used by the DES Collaboration. We show that the additional data produce cosmological parameters that are tighter but consistent with those obtained from larger scales, while also constraining the distribution of baryons. In particular, we measure the mass scale at which haloes have lost half of their gas, $\log\,M_{\rm c}=14.38^{+0.60}_{-0.56}\log(h^{-1}{\rm M_{ \odot}})$, and a parameter that quantifies the weighted amplitudes of the present-day matter inhomogeneities, $S_8=0.799^{+0.023}_{-0.015}$. Our constraint on $S_8$ is statistically compatible with that inferred from the Planck satellite's data at the $0.9\sigma$ level. We find instead a $1.4\sigma$ shift in comparison to that from the official DES Y3 cosmic shear, because of different choices in the modelling of intrinsic alignment, non-linearities, baryons, and lensing shear ratios. We conclude that small scales in cosmic shear data contain valuable astrophysical and cosmological information and thus should be included in standard analyses.

Matter power spectrum

Cold dark matter

Sigma

Baryon Acoustic Oscillations

Structure formation

10.48550/arxiv.2303.05537

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The MillenniumTNG Project: Refining the one-halo model of red and blue galaxies at different redshifts

arXiv (Cornell University) (2022)

Boryana Hadzhiyska Lars Hernquist Daniel J. Eisenstein Ana Delgado Sownak Bose

Luminous red galaxies (LRGs) and blue star-forming emission-line galaxies (ELGs) are key tracers of large-scale structure used by cosmological surveys. Theoretical predictions for such data are often done via simplistic models for the galaxy-halo connection. In this work, we use the large, high-fidelity hydrodynamical simulation of the MillenniumTNG project (MTNG) to inform a new phenomenological approach for obtaining an accurate and flexible galaxy-halo model on small scales. Our aim is to study LRGs and ELGs at two distinct epochs, $z = 1$ and $z = 0$, and recover their clustering down to very small scales, $r \sim 0.1 \ {\rm Mpc}/h$, i.e. the one-halo regime, while a companion paper extends this to a two-halo model for larger distances. The occupation statistics of ELGs in MTNG inform us that: (1) the satellite occupations exhibit a slightly super-Poisson distribution, contrary to commonly made assumptions, and (2) that haloes containing at least one ELG satellite are twice as likely to host a central ELG. We propose simple recipes for modeling these effects, each of which calls for the addition of a single free parameter to simpler halo occupation models. To construct a reliable satellite population model, we explore the LRG and ELG satellite radial and velocity distributions and compare them with those of subhalos and particles in the simulation. We find that ELGs are anisotropically distributed within halos, which together with our occupation results provides strong evidence for cooperative galaxy formation (manifesting itself as one-halo galaxy conformity); i.e.~galaxies with similar properties form in close proximity to each other. Our refined galaxy-halo model represents a useful improvement of commonly used analysis tools and thus can be of help to increase the constraining power of large-scale structure surveys.

Satellite galaxy

10.48550/arxiv.2210.10068

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Dissecting and modelling galaxy assembly bias

Monthly Notices of the Royal Astronomical Society (2021)

Xiaoju Xu Idit Zehavi Sergio Contreras

Understanding the galaxy-halo connection is fundamental for contemporary models of galaxy clustering. The extent to which the haloes' assembly history and environment impact galaxy clustering (a.k.a. galaxy assembly bias; GAB), remains a complex and challenging problem. Using a semi-analytic galaxy formation model, we study the individual contributions of different secondary halo properties to the GAB signal. These are obtained by comparing the clustering of stellar-mass selected samples to that of shuffled samples where the galaxies are randomly reassigned to haloes of fixed mass and a specified secondary halo property. We explore a large range of internal halo properties and environmental measures. We find that commonly used properties like halo age or concentration amount to only 20-30 per cent of the signal, while the smoothed matter density or the tidal anisotropy can account for the full level of GAB (though care should be given to the specific definition). For the "successful" measures, we examine the occupancy variations and the associated changes in the halo occupation function parameters. These are used to create mock catalogues that reproduce the full level of GAB. Finally, we propose a practical modification of the standard halo occupation distribution model, which can be tuned to any level of assembly bias. Fitting the parameters to our semi-analytic model, we demonstrate that the corresponding mock catalogue recovers the target level of GAB as well as the occupancy variations. Our results enable producing realistic mock catalogues and directly inform theoretical modelling of assembly bias and attempts to detect it in the Universe.

Halo effect

10.1093/mnras/stab100

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Citations (64)

Factores explicativos de los resultados empresariales: un estudio de las empresas españolas

Revista Venezolana de Gerencia (2012)

Patricia Huerta Riveros Sergio Contreras Paloma Almodóvar Liliana Pedraja-Rejas

Los resultados empresariales se explican por diversos factores, que a su vez, influyen en la supervivencia de la empresa. Es por ello, que el presente artículo persigue dos objetivos. En primer lugar, realizar una revisión bibliográfica de los factores que explican e influyen en los resultados empresariales, y en segundo lugar, contrastar los planteamientos teóricos para aportar evidencia empírica al respecto, a través de un análisis comparativo con estudios previos. La contrastación se realiza sobre un panel completo de empresas industriales españolas, para el periodo 2000-2005. Utilizando análisis de componentes de varianza se identifican los factores que explican el 95.6% de los resultados empresariales y empleando un modelo de efectos aleatorios se descubre que éstos también influyen en los resultados obtenidos. Los resultados del estudio sugieren que el efecto empresa es 17.8 veces superior con respecto al efecto sector en la determinación de los resultados empresariales; y el efecto localización explica el 7.39% de los resultados. Finalmente, se concluye, que los factores sector, tiempo, localización, y principalmente el factor empresa, deberán ser considerados por aquellas organizaciones que desean alcanzar mejores resultados.

10.31876/revista.v17i57.10672

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Citations (1)

The BACCO simulation project: biased tracers in real space

arXiv (Cornell University) (2021)

Matteo Zennaro Raúl E. Angulo Marcos Pellejero-Ibáñez Jens Stücker Sergio Contreras

We present an emulator for the two-point clustering of biased tracers in real space. We construct this emulator using neural networks calibrated with more than $400$ cosmological models in a 8-dimensional cosmological parameter space that includes massive neutrinos an dynamical dark energy. The properties of biased tracers are described via a Lagrangian perturbative bias expansion which is advected to Eulerian space using the displacement field of numerical simulations. The cosmology-dependence is captured thanks to a cosmology-rescaling algorithm. We show that our emulator is capable of describing the power spectrum of galaxy formation simulations for a sample mimicking that of a typical Emission-Line survey at $z \sim 1$ with an accuracy of $1-2\%$ up to nonlinear scales $k \sim 0.7 h \mathrm{Mpc}^{-1}$.

10.48550/arxiv.2101.12187

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Citations (23)

The cosmological dependence of halo and galaxy assembly bias

Monthly Notices of the Royal Astronomical Society (2021)

Sergio Contreras Jonás Chaves-Montero Matteo Zennaro Raúl E. Angulo

One of the main predictions of excursion set theory is that the clustering of dark matter haloes only depends on halo mass. However, it has been long established that the clustering of haloes also depends on other properties, including formation time, concentration, and spin; this effect is commonly known as halo assembly bias. We use a suite of gravity-only simulations to study the dependence of halo assembly bias on cosmology; these simulations cover cosmological parameters spanning 10$σ$ around state-of-the-art best-fitting values, including standard extensions of the $Λ$CDM paradigm such as neutrino mass and dynamical dark energy. We find that the strength of halo assembly bias presents variations smaller than 0.05 dex across all cosmologies studied for concentration and spin selected haloes, letting us conclude that the dependence of halo assembly bias upon cosmology is negligible. We then study the dependence of galaxy assembly bias (i.e. the manifestation of halo assembly bias in galaxy clustering) on cosmology using subhalo abundance matching. We find that galaxy assembly bias also presents very small dependence upon cosmology ($\sim$ 2$\%$-4$\%$ of the total clustering); on the other hand, we find that the dependence of this signal on the galaxy formation parameters of our galaxy model is much stronger. Taken together, these results let us conclude that the dependence of halo and galaxy assembly bias on cosmology is practically negligible.

10.1093/mnras/stab2367

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Citations (20)

Decomposition of butyl dixanthogen in the presence of cationic micelles

Canadian Journal of Chemistry (1976)

Luis Sepúlveda Sergio Contreras

The decomposition of butyl dixanthogen in the presence of cetyl trimethylammonium bromide (CTA) at pH 10.5 is studied. CTA micelles strongly catalyze the decomposition. A great difference is also found between freshly prepared dixanthogen and that stored pure or dissolved in dioxane for more than one month. A general mechanism is proposed to account for the results obtained.

Cationic polymerization

10.1139/v76-012

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Citations (14)