Papers by Alberto Manrique
The Astrophysical Journal, Nov 1, 1995
This is the rst paper of a series of two devoted to develop a practical method to describe the gr... more This is the rst paper of a series of two devoted to develop a practical method to describe the growth history of bound virialized objects in the gravitational instability scenario without resorting to N-body simulations. Here we present the basic tool of this method, \the con uent system formalism", which allows us to follow the ltering evolution of peaks in a random Gaussian eld of density uctuations. This is applied to derive the theoretical mass function of objects within the peak model framework. Along the process followed for the derivation of this function, we prove that the Gaussian window is the only one consistent with the peak model ansatz. We also give a well justi ed derivation of the density of peaks with density contrast upcrossing a given threshold in in nitesimal ranges of scale and correct this scale function for the cloud-in-cloud e ect. Finally, we characterize the form of the mass vs. scale and the critical overdensity vs. collapse time relations which are physically consistent with the peak model in an Einstein-de Sitter universe with density eld endowed with di erent power spectra. The result is a fully justi ed semianalytical mass function which is close to the Press & Schechter (1974) one giving good ts to N-body simulations. But the interest of the con uent system formalism is not { 2 { merely formal. It allows us to distinguish between accretion and merger events, which is essential for the detailed modelling of the clustering process experienced by objects.
arXiv (Cornell University), Jan 5, 2007
We show that the two basic assumptions of the model recently proposed by Manrique and coworkers f... more We show that the two basic assumptions of the model recently proposed by Manrique and coworkers for the universal density profile of cold dark matter (CDM) halos, namely that these objects grow inside out in periods of smooth accretion and that their mass profile and its radial derivatives are all continuous functions, are both well understood in terms of the very nature of CDM. Those two assumptions allow one to derive the typical density profile of halos of a given mass from the accretion rate characteristic of the particular cosmology. This profile was shown by Manrique and coworkers to recover the results of numerical simulations. In the present paper, we investigate its behavior beyond the ranges covered by present-day N-body simulations. We find that the central asymptotic logarithmic slope depends crucially on the shape of the power spectrum of density perturbations: it is equal to a constant negative value for power-law spectra and has central cores for the standard CDM power spectrum. The predicted density profile in the CDM case is well fitted by the 3D Sérsic profile over at least 10 decades in halo mass. The values of the Sérsic parameters depend on the mass of the structure considered. A practical procedure is provided that allows one to infer the typical values of the best NFW or Sérsic fitting law parameters for halos of any mass and redshift in any given standard CDM cosmology.
arXiv (Cornell University), Nov 30, 2002
We construct a physically motivated analytical model for the quasar luminosity function, based on... more We construct a physically motivated analytical model for the quasar luminosity function, based on the joint star formation and feeding of massive black holes suggested by the observed correlation between the black hole mass and the stellar mass of the hosting spheroids. The parallel growth of massive black holes and host galaxies is assumed to be triggered by major mergers of haloes. The halo major merger rate is computed in the frame of the extended Press-Schechter model. The evolution of black holes on cosmological timescales is achieved by the integration of the governing set of differential equations, established from a few reasonable assumptions that account for the distinct (Eddington-limited or supply-limited) accretion regimes. Finally, the typical lightcurves of the reactivated quasars are obtained under the assumption that, in such accretion episodes, the fall of matter onto the black hole is achieved in a selfregulated stationary way. The predicted quasar luminosity function is compared to the luminosity functions of the 2dF QSO sample and other, higher redshift data. We find good agreement in all cases, except for z < 1 where the basic assumption of our model is likely to break down.
The Astrophysical Journal, Apr 22, 2015
The modeling of galaxy formation and reionization, two central issues of modern cosmology, relies... more 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 expressions 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.
Monthly Notices of the Royal Astronomical Society, Aug 1, 2018
We present ALMA Atacama Compact Array (ACA) 870 µm continuum maps of 28 infrared-bright SDSS quas... more We present ALMA Atacama Compact Array (ACA) 870 µm continuum maps of 28 infrared-bright SDSS quasars with Herschel/SPIRE detections at redshifts 2-4, the largest such sample ever observed with ALMA. The ACA detections are centred on the SDSS coordinates to within 1 for about 80 per cent of the sample. Larger offsets indicate that the far-infrared (FIR) emission detected by Herschel might come from a companion source. The majority of the objects (∼70 per cent) have unique ACA counterparts within the SPIRE beam down to 3-4 resolution. Only a 30 per cent of the sample show clear evidence for multiple sources with secondary counterparts contributing to the total 870 µm flux within the SPIRE beam by at least 25 per cent. We discuss the limitations of the data based on simulated pairs of point-like sources at the resolution of the ACA and present an extensive comparison of our findings with recent works on the multiplicities of sub-millimetre galaxies. We conclude that, despite the coarse resolution of the ACA, our data support the idea that, for a large fraction of FIR-bright quasars, the sub-mm emission comes from single sources. Our results suggest that, on average, optically bright quasars with strong FIR emission are not triggered by early-stage mergers but are instead, together with their associated star formation rates, the outcome of either late-stage mergers or secular processes.
Monthly Notices of the Royal Astronomical Society, Jul 13, 2012
In a recent paper, Salvador-Solé et al. have derived the typical inner structure of dark matter h... more In a recent paper, Salvador-Solé et al. have derived the typical inner structure of dark matter haloes from that of peaks in the initial random Gaussian density field, determined by the power spectrum of density perturbations characterizing the hierarchical cosmology under consideration. In this paper, we extend this formalism to the typical kinematics and triaxial shape of haloes. Specifically, we establish the link between such halo properties and the power spectrum of density perturbations through the typical shape of peaks. The trends of the predicted typical halo shape, pseudo-phase-space density and anisotropy profiles are in good agreement with the results of numerical simulations. Our model sheds light on the origin of the power-law-like pseudo-phase-space density profile for virialized haloes.
Monthly Notices of the Royal Astronomical Society, Sep 16, 2021
In Paper I we used the CUSP formalism to derive from first principles and no single free paramete... more 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.
arXiv (Cornell University), Oct 13, 1998
High resolution cosmological N-body simulations show that the density profiles of dark matter hal... more High resolution cosmological N-body simulations show that the density profiles of dark matter halos in hierarchical cosmogonies are universal, with low mass halos typically denser than more massive ones. This mass-density correlation is interpreted as reflecting the earlier formation of less massive objects. We investigate this hypothesis in the light of formation times defined as the epoch at which halos experience their last major merger. We find that the characteristic density and the scale radius of halos are essentially proportional, respectively, to the critical density of the universe and the virial radius at the time of their formation. These two relations are consistent with the following simple evolutionary picture. Violent relaxation caused by major mergers rearrange the structure of halos leading to a universal dimensionless density profile. Between major mergers, halos gradually grow through the accretion of surrounding layers by keeping the central part steady and only expanding their virial radius as the critical density of the universe diminishes.
We present an Analytic Model of Intergalactic-medium and GAlaxy evolution since the dark ages. AM... more 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. Subject headings: galaxies-galaxies: formation-dark matter-intergalactic medium 1 Even though current simulations start at z > ∼ 100, convergence of galaxy properties is only found up to z ∼ 7 for the most favorable case of relatively low resolutions (Schaye et al. 2010).
The Astrophysical Journal, 2019
We present evidence for the discovery of a protocluster of starburst galaxies (Lyα emitters, or L... more We present evidence for the discovery of a protocluster of starburst galaxies (Lyα emitters, or LAEs) near the end of the epoch of reionization. The recent trend in the search for high-redshift protoclusters focuses on utilizing bias tracers, such as luminous starburst galaxies, as signposts of overdensities. Thus, we conducted a photometric selection of LAE candidates around a pair of spatially close, luminous LAEs at z=6.5 in the Subaru/XMM-Newton Deep Survey field, using OSIRIS in its imaging mode at the 10.4 m Gran Telescopio Canarias in La Palma, Spain. The spectroscopic follow-up was done with OSIRIS in its multiobject spectroscopy capability. We have spectroscopically confirmed 10 LAEs via their recognizable Lyα emission feature. The redshifts of these LAEs shed light on their 3D distributions within the observing window defined by the photometric selection. We have derived the galaxy number density contrast of 3.18 , comparable to the Coma cluster. Thus, our careful analysis has pointed to evidence that this protocluster would evolve into a Coma-analog cluster in the present-day universe.
The growth of Super Massive Black Holes and the parallel development of activity in galactic nucl... more The growth of Super Massive Black Holes and the parallel development of activity in galactic nuclei are implemented in an analytic code of hierarchical clustering. The evolution of the luminosity function of quasars and AGN will be computed with special attention paid to the connection between quasars and Seyfert galaxies. One of the major interests of the model is the parallel study of quasar formation and evolution and the History of Star Formation.
The Astrophysical Journal, 2015
The modeling of galaxy formation and reionization, two central issues of modern cosmology, relies... more 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 expressions 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.
The Astrophysical Journal, 1995
This is the rst paper of a series of two devoted to develop a practical method to describe the gr... more This is the rst paper of a series of two devoted to develop a practical method to describe the growth history of bound virialized objects in the gravitational instability scenario without resorting to N-body simulations. Here we present the basic tool of this method, \the con uent system formalism", which allows us to follow the ltering evolution of peaks in a random Gaussian eld of density uctuations. This is applied to derive the theoretical mass function of objects within the peak model framework. Along the process followed for the derivation of this function, we prove that the Gaussian window is the only one consistent with the peak model ansatz. We also give a well justi ed derivation of the density of peaks with density contrast upcrossing a given threshold in in nitesimal ranges of scale and correct this scale function for the cloud-in-cloud e ect. Finally, we characterize the form of the mass vs. scale and the critical overdensity vs. collapse time relations which are physically consistent with the peak model in an Einstein-de Sitter universe with density eld endowed with di erent power spectra. The result is a fully justi ed semianalytical mass function which is close to the Press & Schechter (1974) one giving good ts to N-body simulations. But the interest of the con uent system formalism is not { 2 { merely formal. It allows us to distinguish between accretion and merger events, which is essential for the detailed modelling of the clustering process experienced by objects.
The Astrophysical Journal, 2001
14853 (riccardo,haynes)@astrosun.tn.cornell.edu abstract We derive the atomic hydrogen content fo... more 14853 (riccardo,haynes)@astrosun.tn.cornell.edu abstract We derive the atomic hydrogen content for a total of 1900 spirals in the fields of eighteen nearby clusters. By comparing the HI deficiency distributions of the galaxies inside of and outside of one Abell radius () of each cluster, we find that two thirds of the clusters in our sample show a dearth of neutral gas in their interiors. Possible connections between the gaseous deficiency and the characteristics of both the underlying galaxies and their environment are investigated in order to gain insight into the mechanisms responsible for HI depletion. While we do not find a statistically significant variation of the fraction of HIdeficient spirals in a cluster with its global properties, a number of correlations emerge that argue in favor of the interplay between spiral disks and their environment. In the clusters in which neutral gas deficiency is pronounced, we see clear indications that the degree of HI depletion is related to the morphology of the galaxies and not to their optical size: early-type and, probably, dwarf spirals are more easily emptied of gas than the intermediate Sbc-Sc types. Gas contents below one tenth, and even one hundredth, of the expectation value have been measured, implying that gas removal is very efficient. The radial extent of the region with significant gas ablation can reach up to 2. Within this zone, the proportion of gas-poor spirals increases continuously towards the cluster center. The wealth of 21-cm data collected for the Virgo region has made it possible to study the 2D pattern of HI deficiency in that cluster. The map of gas deficiency in the Virgo central area points to an scenario in which gas losses result from the interaction of the disks with the inner hot intracluster gas around M87. We also find evidence that gas-poor spirals in HI-deficient clusters move on orbits more radial than those of the gas-rich objects. The implications of all these results on models of how galaxies interact with their environment are reviewed. Hydrodynamic effects appear as the most plausible cause of HI removal.
The Astrophysical Journal, 2005
We present an entirely analytic model for a preheated, polytropic intergalactic medium in hydrost... more We present an entirely analytic model for a preheated, polytropic intergalactic medium in hydrostatic equilibrium within a NFW dark halo potential in which the evolution of the halo structure between major merger events proceeds inside-out by accretion. This model is used to explain, within a standard ΛCDM cosmogony, the observed X-ray properties of nearby relaxed, non-cooling flow groups and clusters of galaxies. We find that our preferred solution to the equilibrium equations produces scaling relations in excellent agreement with observations, while simultaneously accounting for the typical structural characteristics of the distribution of the diffuse baryons. In the class of preheating models, ours stands out because it offers a unified description of the intrahalo medium for galaxy systems with total masses above ∼ 2 × 10 13 M ⊙ , does not produce baryonic configurations with large isentropic cores, and reproduces faithfully the observed behavior of the gas entropy at large radii. All this is achieved with a moderate level of energy injection of about half a keV, which can be easily accommodated within the limits of the total energy released by the most commonly invoked feedback mechanisms, as well as with a polytropic index of 1.2, consistent with both many observational determinations and predictions from high-resolution gas-dynamical simulations of non-cooling flow clusters. More interestingly, our scheme offers a physical motivation for the adoption of this specific value of the polytropic index, as it is the one that best ensures the conservation after halo virialization of the balance between the total specific energies of the gas and dark matter components for the full range of masses investigated.
The Astrophysical Journal, 1998
In two previous papers a semi-analytical model was presented for the hierarchical clustering of h... more In two previous papers a semi-analytical model was presented for the hierarchical clustering of halos via gravitational instability from peaks in a random Gaussian field of density fluctuations. This model is better founded than the extended Press-Schechter model, which is known to agree with numerical simulations and to make similar predictions. The specific merger rate, however, shows a significant departure at intermediate captured masses. The origin of this was suspected as being the rather crude approximation used for the density of nested peaks. Here, we seek to verify this suspicion by implementing a more accurate expression for the latter quantity which accounts for the correlation among peaks. We confirm that the inclusion of the peak-peak correlation improves the specific merger rate, while the good behavior of the remaining quantities is preserved.
Monthly Notices of the Royal Astronomical Society: Letters, 2012
Using the model for (bottom-up) hierarchical halo growth recently developed by Salvador-Solé et a... more Using the model for (bottom-up) hierarchical halo growth recently developed by Salvador-Solé et al., we derive the typical spherically averaged density profile for haloes with several relevant masses in the concordant warm dark matter (WDM) cosmology with non-thermal sterile neutrinos of two different masses. The predicted density profiles become flat at small radii, as expected from the effects of the spectrum cutoff. The core cannot be resolved, however, because the non-null particle velocity yields the fragmentation of minimum mass protohaloes in small nodes, which invalidates the model at the corresponding radii.
Monthly Notices of the Royal Astronomical Society, 2014
Comparing the excursion set and CUSP formalisms for the derivation of the halo mass function, we ... more 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 ∆ 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, ∆ vir , equal to ∼ 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 ∼ 0.9 times the usual top-hat density contrast for spherical collapse.
Monthly Notices of the Royal Astronomical Society, 2012
In a recent paper, Salvador-Solé et al. have derived the typical inner structure of dark matter h... more In a recent paper, Salvador-Solé et al. have derived the typical inner structure of dark matter haloes from that of peaks in the initial random Gaussian density field, determined by the power spectrum of density perturbations characterizing the hierarchical cosmology under consideration. In this paper, we extend this formalism to the typical kinematics and triaxial shape of haloes. Specifically, we establish the link between such halo properties and the power spectrum of density perturbations through the typical shape of peaks. The trends of the predicted typical halo shape, pseudo-phase-space density and anisotropy profiles are in good agreement with the results of numerical simulations. Our model sheds light on the origin of the power-law-like pseudo-phase-space density profile for virialized haloes.
Monthly Notices of the Royal Astronomical Society, 2005
Relaxed dark matter haloes are found to exhibit the same universal density profiles regardless of... more Relaxed dark matter haloes are found to exhibit the same universal density profiles regardless of whether they form in hierarchical cosmologies or via spherical collapse. Likewise, the shape parameters of haloes formed hierarchically do not seem to depend on the epoch in which the last major merger took place. Both findings suggest that the density profile of haloes does not depend on their aggregation history. Yet, this possibility is apparently at odds with some correlations involving the scale radius r s found in numerical simulations. Here we prove that the scale radius of relaxed, non-rotating, spherically symmetric haloes endowed with the universal density profile is determined exclusively by the current values of four independent, though correlated, quantities: mass, energy and their respective instantaneous accretion rates. Under this premise and taking into account the inside-out growth of haloes during the accretion phase between major mergers, we build a simple physical model for the evolution of r s along the main branch of halo merger trees that reproduces all the empirical trends shown by this parameter in N-body simulations. This confirms the conclusion that the empirical correlations involving r s do not actually imply the dependence of this parameter on the halo aggregation history. The present results give strong support to the explanation put forward in a recent paper by Manrique et al. for the origin of the halo universal density profile.
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Papers by Alberto Manrique