arXiv subjects

Alberto Manrique

Publications and source records attributed to Alberto Manrique.

At least 19 recordsLinked to original sources

arXiv2025

The Tidal Torque Theory Revisited: II. Rotational Halo Properties

The peak model of structure formation was built more than fifty years ago with the aim to address the origin of dark matter halo rotation in the tidal torque theory (TTT). Paradoxically, it has allowed one to explain and reproduce all halo properties found in cosmological simulations except their rotation, which remains to be understood. With the present two Papers we remedy this anomaly. In Paper I we derived the angular momentum (AM) of protohalos centered on triaxial peaks of suited scale, taking into account that, to leading order, their density profile is smooth and homogeneous. Here we use that result to derive the AM of these objects, accounting for the fact that their actual density profile is slightly outward decreasing and lumpy so that they do not collapse monolithically at once, but progressively from inside out, undergoing mergers during the process. By monitoring in detail their resulting mass and AM growth, we characterize the spin distribution of final halos and the precise mass and radial distribution of their inner mean specific AM. The results obtained explain and reproduce the rotational properties of simulated halos.

astro-ph.CO↗

arXiv2025

An Accurate Comprehensive Approach to Substructure: IV. Dynamical Friction

In three previous Papers we analysed the origin of the properties of halo substructure found in simulations. This was achieved by deriving them analytically in the peak model of structure formation, using the statistics of nested peaks (with no free parameter) plus a realistic model of subhalo stripping and shock-heating (with only one parameter). However, to simplify the treatment we neglected dynamical friction (DF). Here, we revisit that work by including it. That is done in a fully analytic manner, i.e. avoiding the integration of subhalo orbital motions. This leads to simple accurate expressions for the abundance and radial distribution of subhaloes of different masses, which disentangle the effects of DF from those of tidal stripping and shock-heating. This way we reproduce and explain the results of simulations and extend them to haloes of any mass, redshift and formation times in the desired cosmology.

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arXiv2024

Halo bias in the peak model. A first-principles non-parametric approach

The Press-Schechter (PS) and excursion set (ES) models of structure formation fail in reproducing the halo bias found in simulations, while the excursion set-peaks (ESP) formalism built in the peak model reproduces it only at high masses and does not address in a fully satisfactory manner peak nesting and the mass and time of ellipsoidal collapse of triaxial peaks in the Gaussian-smoothed density field. Here we apply the CUSP formalism fixing all these issues from first principles and with no free parameters to infer the Lagrangian local peak bias parameters, which adopt very simple analytic expressions similar to those found in the PS and ES models. The predicted Eulerian linear halo bias recovers the results of simulations. More specifically, we show that the only small departure observed at intermediate and low masses can be due to the spurious halo splitting and grouping caused by the Spherical Overdensity halo-finding algorithm used in simulations.

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arXiv2024

Origin and full characterization of the secondary (assembly) halo bias

The clustering of dark matter halos depends not only on their mass, the so-called primary bias, but also on their internal properties, the so-called secondary bias. While the former effect is well-understood within the Press-Schechter (PS) and excursion set (ES) models of structure formation, the latter is not. In those models, protohalos are fully characterised by their height and scale, which determine the halo mass and collapse time, so there is no room for any other halo property. This is why the secondary bias was believed not to be innate but due to the distinct merger rate of halos lying in different backgrounds, and dubbed assembly bias. However, it is now admitted that mergers leave no imprint in the inner halo properties. In fact, the innate origin of the secondary bias cannot be discarded because, in the more realistic peak model of structure formation, halo seeds are characterized by one additional property: the peak curvature. Here we use the confluent system of peak trajectories (CUSP) formalism to show that peaks lying in different backgrounds have different mean curvatures, which in turn cause them to evolve in halos with different typical inner properties. The dependence we find of the properties on halo background (or halo clustering) reproduces the results of simulations.

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arXiv2024

The Tidal Torque Theory Revisited. I. Protohalo Angular Momentum

In the tidal-torque theory, the angular momentum (AM) of dark matter halos arises from the tidal torque suffered by aspherical collapsing patches due to surrounding mass fluctuations. This theory was implemented in the peak model where protohalos are ellipsoidal. However, the adopted delimitation of these objects was doubtful and the protohalo AM was calculated numerically, which complicated the interpretation of the result and compromised its applicability. In addition, the AM of final halos was derived without taking into account non-linear effects. Here, we re-derive the protohalo AM in the peak model, delimiting ellipsoids in the usual natural way and following a novel fully analytic approach that leads to a very simple and practical expression. The predicted AM is shown to fully agree with the results of cosmological simulations. In Paper II, we will apply this model to infer the rotational properties of relaxed halos, accounting for shell-crossing and major mergers.

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arXiv2023

Accurate Analytic Mass-Scale Relations for Dark Matter Haloes of all Masses and Redshifts

CUSP is a powerful formalism that recovers, from first principles and with no free parameter, all the macroscopic properties of dark matter haloes found in cosmological N-body simulations and unveils the origin of their characteristic features. Since it is not restricted by the limitations of simulations, it covers the whole mass and redshift ranges. In the present Paper we use CUSP to calculate the mass-scale relations holding for halo density profiles fitted to the usual NFW and Einasto functions in the most relevant cosmologies and for the most usual mass definitions. We clarify the origin of these relations and provide accurate analytic expressions holding for all masses and redshifts. The performance of those expressions is compared to that of previous models and to the mass-concentration relation spanning more than 20 orders of magnitude in mass at $z=0$ obtained in recent simulations of a 100 GeV WIMP universe.

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arXiv2022

Lyman-$\alpha$ Emitting Galaxies (LAEs) at Cosmic Dawn: Implications and Predictions

The detection of Lyman-$\alpha$ emitting galaxies (LAEs) puts severe constraints on the reionization history. In this Paper we derive the properties of very high-$z$ LAEs predicted in the only two reionization scenarios shown in a previous Paper to be consistent with current data on 15 independent evolving global (or averaged) cosmic properties regarding luminous objects and the intergalactic medium and the optical depth to electron scattering of ionized hydrogen to CMB photons: one with a monotonic behavior, which is completed by $z=6$, as commonly considered, and another one with a non-monotonic behavior with two full ionization events at $z=6$ and $z=10$. We find that the Ly$\alpha$ luminosity functions of very high-$z$ LAEs are very distinct in those two scenarios. Thus, comparing these predictions to the observations that will soon be available thanks to new instruments such as the James Webb Space Telescope, it should be possible to unveil the right reionization scenario. In the meantime, we can compare the predicted redshift distribution and UV (or Lyman-$\alpha$) luminosities of very high-$z$ LAEs to those of the few objects already observed at $z>7.5$. By doing that we find that such data are in tension with the single reionization scenario, while they are fully compatible with the double reionization scenario.

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arXiv2022

An Accurate Comprehensive Approach to Substructure: III. Masses and Formation Times of the Host Haloes

With this Paper we complete a comprehensive study of substructure in dark matter haloes. In Paper I we derived the radial distribution and mass function (MF) of accreted subhaloes (scaled to the radius and mass of the host halo) and showed they are essentially universal. This is not the case, however, for those of stripped subhaloes, which depend on halo mass and assembly history. In Paper II we derived these latter properties in the simplest case of purely accreting haloes. Here we extend the study to ordinary haloes having suffered major mergers. After showing that all the properties of substructure are encoded in the mean truncated-to-original subhalo mass ratio profile, we demonstrate that the dependence of the subhalo MF on halo mass arises from their mass-dependent concentration, while the shape of the subhalo radial distribution depends on the time of the last major merger of the host halo. In this sense, the latter property is a better probe of halo formation time than the former. Unfortunately, this is not the case for the radial distribution of satellites as this profile is essentially disconnected from subhalo stripping and the properties of accreted subhaloes are independent of the halo formation time.

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arXiv2021

An Accurate Comprehensive Approach to Substructure: I. Accreted Subhaloes

This is the first of a series of three Papers devoted to the study of halo substructure in hierarchical cosmologies by means of the CUSP formalism. In the present Paper we derive the properties of subhaloes and diffuse dark matter (dDM) accreted onto haloes and their progenitors. Specifically, we relate the dDM present at any time in the inter-halo medium of the real Universe or a cosmological simulation with the corresponding free-streaming mass or the halo resolution mass, respectively, and establish the link between subhaloes and their seeds in the initial density field. By monitoring the collapse and virialisation of haloes, we derive from first principles and with no single free parameter the abundance and radial distribution of dDM and subhaloes accreted onto them. Our predictions are in excellent agreement with the results of simulations, but for the predicted fraction of accreted dDM, which is larger than reported in previous works as they only count the dDM accreted onto the final halo, not onto its progenitors. The derivation pursued here clarifies the origin of some key features of substructure. Overall, our results demonstrate that CUSP is a powerful tool for understanding halo substructure and extending the results of simulations to haloes with arbitrary masses, redshifts and formation times in any hierarchical cosmology endowed with random Gaussian density perturbations.

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arXiv2021

An Accurate Comprehensive Approach to Substructure: II. Stripped Subhaloes

In Paper I we used the CUSP formalism to derive from first principles and no single free parameter the accurate abundance and radial distribution of both diffuse DM (dDM) and subhaloes accreted onto haloes and their progenitors at all previous times. Here we use those results as initial conditions for the monitoring of the evolution of subhaloes and dDM within the host haloes. Specifically, neglecting dynamical friction, we accurately calculate the effects of repetitive tidal stripping and heating on subhaloes as they orbit inside the host halo and infer the amount of dDM and subsubhaloes they release into the intra-halo medium. We then calculate the expected abundance and radial distribution of stripped subhaloes and dDM. This derivation clarifies the role of halo concentration in substructure and unravels the origin of some key features found in simulations including the dependence of substructure on halo mass. In addition, it unveils the specific effects of dynamical friction on substructure. The results derived here are for purely accreting haloes. In Paper III we complete the study by addressing the case of low-mass subhaloes, unaffected by dynamical friction, in ordinary haloes having suffered major mergers.

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arXiv2021

Culminating the peak CUSP to descry the dark side of halos

The ConflUent System of Peak trajectories (CUSP) is a rigorous formalism in the framework of the peak theory that allows one to derive from first principles andno free parameters the typical halo properties from the statistics of peaks in the filtered Gaussian random field of density perturbations. The predicted halo mass function, spherically averaged density, velocity dispersion, velocity anisotropy, ellipticity, prolateness and potential profiles, as well as the abundance and number density profiles of accreted and stripped subhalos and diffuse dark matter accurately recover the results of cosmological $N$-body simulations. CUSP is thus a powerful tool for the calculation, in any desired hierarchical cosmology with Gaussian perturbations, of halo properties beyond the mass, redshift and radial ranges covered by simulations. More importantly, CUSP unravels the origin of the characteristic features of those properties. In the present Paper we culminate its construction. We show that all halo properties but those related with subhalo stripping are independent of the assembly history of those objects, and that the Gaussian is the only smoothing window able to find the finite collapsing patches while properly accounting for the entropy increase produced in major mergers.

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arXiv2019

MOS spectroscopy of protocluster candidate galaxies at z=6.5

The epoch corresponding to a redshift of z $\sim 6.5$ is close to full re-ionisation of the Universe, and early enough to provide an intriguing environment to observe the early stage of large-scale structure formation. It is also en epoch that can be used to verify the abundance of a large population of low luminosity star-forming galaxies, that are deemed responsible for cosmic re-ionisation. Here, we present the results of follow-up multi-object spectroscopy using OSIRIS at Gran Telescopio Canarias (GTC) of 16 Ly$\alpha$ emitter (LAE) candidates discovered in the Subaru/XMM Newton Deep Survey. We have securely confirmed 10 LAEs with sufficient signal-to-noise ratio of the Ly$\alpha$ emission line. The inferred star formation rates of the confirmed LAEs are on the low side, within the range 0.9-4.7 M$_{\odot}$ yr$^{-1}$. However, they show relatively high Ly$\alpha$ rest frame equivalent widths. Finally we have shown that the mechanical energy released by the star formation episodes in these galaxies is enough to create holes in the neutral hydrogen medium such that Lyman continuum photons can escape to the intergalactic medium, thus contributing to the re-ionisation of the Universe.

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arXiv2016

Cosmic expansion history from SNe Ia data via information field theory -- the charm code

We present charm (cosmic history agnostic reconstruction method), a novel inference algorithm that reconstructs the cosmic expansion history as encoded in the Hubble parameter $H(z)$ from SNe Ia data. The novelty of the approach lies in the usage of information field theory, a statistical field theory that is very well suited for the construction of optimal signal recovery algorithms. The charm algorithm infers non-parametrically $s(a)=\ln(ρ(a)/ρ_{\mathrm{crit}0})$, the density evolution which determines $H(z)$, without assuming an analytical form of $ρ(a)$ but only its smoothness with the scale factor $a=(1+z)^{-1}$. The inference problem of recovering the signal $s(a)$ from the data is formulated in a fully Bayesian way. In detail, we have rewritten the signal as the sum of a background cosmology and a perturbation. This allows us to determine the maximum a posteriory estimate of the signal by an iterative Wiener filter method. Applying charm to the Union2.1 supernova compilation, we have recovered a cosmic expansion history that is fully compatible with the standard $Λ$CDM cosmological expansion history with parameter values consistent with the results of the Planck mission.

astro-ph.CO↗

arXiv2016

Constraining the epoch of reionization from the observed properties of the high-z Universe

We combine observational data on a dozen independent cosmic properties at high-$z$ with the information on reionization drawn from the spectra of distant luminous sources and the cosmic microwave background (CMB) to constrain the interconnected evolution of galaxies and the intergalactic medium since the dark ages. The only acceptable solutions are concentrated in two narrow sets. In one of them reionization proceeds in two phases: a first one driven by Population III stars, completed at $z\sim 10$, and after a short recombination period a second one driven by normal galaxies, completed at $z\sim 6$. In the other set both kinds of sources work in parallel until full reionization at $z\sim 6$. The best solution with double reionization gives excellent fits to all the observed cosmic histories, but the CMB optical depth is 3-$σ$ larger than the recent estimate from the Planck data. Alternatively, the best solution with single reionization gives less good fits to the observed star formation rate density and cold gas mass density histories, but the CMB optical depth is consistent with that estimate. We make several predictions, testable with future observations, that should discriminate between the two reionization scenarios. As a byproduct our models provide a natural explanation to some characteristic features of the cosmic properties at high-$z$, as well as to the origin of globular clusters.

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arXiv2015

An Improved Treatment of Cosmological Intergalactic Medium Evolution

The modeling of galaxy formation and reionization, two central issues of modern cosmology, relies on the accurate follow-up of the intergalactic medium (IGM). Unfortunately, owing to the complex nature of this medium, the differential equations governing its ionization state and temperature are only approximate. In this paper, we improve these master equations. We derive new expression for the distinct composite inhomogeneous IGM phases, including all relevant ionizing/recombining and cooling/heating mechanisms, taking into account inflows/outflows into/from halos, and using more accurate recombination coefficients. Furthermore, to better compute the source functions in the equations we provide an analytic procedure for calculating the halo mass function in ionized environments, accounting for the bias due to the ionization state of their environment. Such an improved treatment of IGM evolution is part of a complete realistic model of galaxy formation presented elsewhere.

astro-ph.CO↗

arXiv2014

Leaving the dark ages with AMIGA

We present an Analytic Model of Intergalactic-medium and GAlaxy evolution since the dark ages. AMIGA is in the spirit of the popular semi-analytic models of galaxy formation, although it does not use halo merger trees but interpolates halo properties in grids that are progressively built. This strategy is less memory-demanding and allows one to start the modeling at redshifts high enough and halo masses low enough to have trivial boundary conditions. The number of free parameters is minimized by making the causal connection between physical processes usually treated as independent from each other, which leads to more reliable predictions. But the strongest points of AMIGA are: i) the inclusion of molecular cooling and metal-poor, population III (Pop III) stars, with the most dramatic feedback, and ii) the accurate follow-up of the temperature and volume filling factor of neutral, singly, and doubly ionized regions, taking into account the distinct halo mass functions in those environments. We find the following general results. Massive Pop III stars determine the IGM metallicity and temperature, and the growth of spheroids and disks is self-regulated by that of massive black holes developed from the remnants of those stars. Yet, the properties of normal galaxies and active galactic nuclei appear to be quite insensitive to Pop III star properties owing to the much higher yield of ordinary stars compared to Pop III stars and the dramatic growth of MBHs when normal galaxies begin to develop, which cause the memory loss of the initial conditions.

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arXiv2014

Fixing a Rigorous Formalism for the Accurate Analytic Derivation of Halo Properties

We establish a one-to-one correspondence between virialized haloes and their seeds, namely peaks with a given density contrast at appropriate Gaussian-filtering radii, in the initial Gaussian random density field. This fixes a rigorous formalism for the analytic derivation of halo properties from the linear power spectrum of density perturbations in any hierarchical cosmology. The typical spherically averaged density profile and mass function of haloes so obtained match those found in numerical simulations.

astro-ph.CO↗

arXiv2014

Halo Mass Definition and Multiplicity Function

Comparing the excursion set and CUSP formalisms for the derivation of the halo mass function, we investigate the role of the mass definition in the properties of the multiplicity function of cold dark matter (CDM) haloes. We show that the density profile for haloes formed from triaxial peaks that undergo ellipsoidal collapse and virialisation is such that the ratio between the mean inner density and the outer local density is essentially independent of mass. This causes that, for suited values of the spherical overdensity $Δ$ and the linking length $b$, SO and FoF masses are essentially equivalent to each other and the respective multiplicity functions are essentially the same. The overdensity for haloes having undergone ellipsoidal collapse is the same as if they had formed according to the spherical top-hat model, which leads to a value of $b$ corresponding to the usual virial overdensity, $Δ_{vir}$, equal to $\sim$ 0.2. The multiplicity function resulting from such mass definitions, expressed as a function of the top-hat height for spherical collapse, is very approximately universal in all CDM cosmologies. The reason for this is that, for such mass definitions, the top-hat density contrast for ellipsoidal collapse and virialisation is close to a universal value, equal to $\sim$ 0.9 times the usual top-hat density contrast for spherical collapse.

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