Environmental Influences on the Morphology and Dynamics of Group Size Haloes

We use group size haloes identified with a ``friends of friends'' (FOF) algorithm in a concordance $\Lambda \rm{CDM}$ GADGET2 (dark matter only) simulation to investigate the dependence of halo properties on the environment at $z=0$. The study is carried out using samples of haloes at different distances from their nearest massive {\em cluster} halo. We find that the fraction of haloes with substructure typically increases in high density regions. The halo mean axial ratio $$ also increases in overdense regions, a fact which is true for the whole range of halo mass studied. This can be explained as a reflection of an earlier halo formation time in high-density regions, which gives haloes more time to evolve and become more spherical. Moreover, this interpretation is supported by the fact that, at a given halo-cluster distance, haloes with substructure are more elongated than their equal mass counterparts with no substructure, reflecting that the virialization (and thus sphericalization) process is interrupted by merger events. The velocity dispersion of low mass haloes with strong substructure shows a significant increase near massive clusters with respect to equal mass haloes with low-levels of substructure or with haloes found in low-density environments. The alignment signal between the shape and the velocity ellipsoid principal axes decreases going from lower to higher density regions, while such an alignment is stronger for haloes without substructure. We also find, in agreement with other studies, a tendency of halo major axes to be aligned and of minor axes to lie roughly perpendicular with the orientation of the filament within which the halo is embedded, an effect which is stronger in the proximity of the massive clusters.Comment: 11 pages, 12 figures, accepted for publication in MNRA

Dependencia ambiental de las propiedades de halos de materia oscura /

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2008

Evolución de la actividad nuclear de galaxias centrales en cúmulos de galaxias simulados

En el presente trabajo se estudia la evolución de la actividad nuclear (AGN) en las galaxias más brillantes de cúmulos de galaxias (BCGs) explotando un conjunto de simulaciones hidrodinámicas de cúmulos de galaxias con modelado de acreción y feedback de agujeros negros supermasivos (SMBH). A diferencia de lo que sucede en las observaciones para galaxias de campo, nuestros resultados preliminares sugieren un desfasaje entre el pico de la evolución de la tasa de acreción de los SMBHs y la historia de formación estelar de las BCGs que los contienen. Con respecto a la conexión entre la tasa de formación estelar (SFR) y la actividad nuclear, a lo largo de la evolución es posible detectar momentos en los que en la muestra emerge una relación entre la tasa de acreción y la de formación estelar. Sin embargo, también es posible encontrar instantes en los que ninguna correlación es clara. Atribuimos este resultado, en parte, a las diferentes escalas temporales y espaciales involucradas en los procesos de acreción y formación estelar.In this work, we study the evolution of active galactic nuclei (AGN) in the brightest cluster galaxies (BCGs) by exploiting a suite of hydro-dynamical simulations with modeling of super-massive black hole (SMBH) accretion and feedback. At variance with observational works based on field galaxies, our preliminary results suggest the existence of a delay in the peak of the SMBH accretion rate evolution with respect to the peak in the star formation history of the galaxies. Regarding the connection between star formation rate (SFR) and nuclear activity, it is possible to detect snapshots during the evolution of the simulated BCG sample in which SFR and SMBH accretion rates are correlated. Nevertheless, it can also be envisaged periods in which no correlation is evident. We ascribe this fact to the different time and spatial scales involved in the accretion and star formation processes.Asociación Argentina de Astronomí

Brightest cluster galaxies in cosmological simulations: achievements and limitations of AGN feedback models

We analyze the basic properties of Brightest Cluster Galaxies (BCGs) produced by state of the art cosmological zoom-in hydrodynamical simulations. These simulations have been run with different sub-grid physics included. Here we focus on the results obtained with and without the inclusion of the prescriptions for supermassive black hole (SMBH) growth and of the ensuing Active Galactic Nuclei (AGN) feedback. The latter process goes in the right direction of decreasing significantly the overall formation of stars. However, BCGs end up still containing too much stellar mass, a problem that increases with halo mass, and having an unsatisfactory structure. This is in the sense that their effective radii are too large, and that their density profiles feature a flattening on scales much larger than observed. We also find that our model of thermal AGN feedback has very little effect on the stellar velocity dispersions, which turn out to be very large. Taken together, these problems, which to some extent can be recognized also in other numerical studies typically dealing with smaller halo masses, indicate that on one hand present day sub-resolution models of AGN feedback are not effective enough in diminishing the global formation of stars in the most massive galaxies, but on the other hand they are relatively too effective in their centers. It is likely that a form of feedback generating large scale gas outflows from BCGs precursors, and a more widespread effect over the galaxy volume, can alleviate these difficulties.Comment: 17 pages, 14 figures, accepted for publication on MNRAS, comments welcom

Kinetic AGN Feedback Effects on Cluster Cool Cores Simulated using SPH

We implement novel numerical models of AGN feedback in the SPH code GADGET-3, where the energy from a supermassive black hole (BH) is coupled to the surrounding gas in the kinetic form. Gas particles lying inside a bi-conical volume around the BH are imparted a one-time velocity (10,000 km/s) increment. We perform hydrodynamical simulations of isolated cluster (total mass 10^14 /h M_sun), which is initially evolved to form a dense cool core, having central T<10^6 K. A BH resides at the cluster center, and ejects energy. The feedback-driven fast wind undergoes shock with the slower-moving gas, which causes the imparted kinetic energy to be thermalized. Bipolar bubble-like outflows form propagating radially outward to a distance of a few 100 kpc. The radial profiles of median gas properties are influenced by BH feedback in the inner regions (r<20-50 kpc). BH kinetic feedback, with a large value of the feedback efficiency, depletes the inner cool gas and reduces the hot gas content, such that the initial cool core of the cluster is heated up within a time 1.9 Gyr, whereby the core median temperature rises to above 10^7 K, and the central entropy flattens. Our implementation of BH thermal feedback (using the same efficiency as kinetic), within the star-formation model, cannot do this heating, where the cool core remains. The inclusion of cold gas accretion in the simulations produces naturally a duty cycle of the AGN with a periodicity of 100 Myr.Comment: 22 pages, 11 figures, version accepted for publication in MNRAS, references and minor revisions adde

The early phases of galaxy clusters formation in IR: coupling hydrodynamical simulations with GRASIL3D

We compute and study the infrared and sub-mm properties of high redshift ($z \gtrsim 1$) simulated clusters and proto-clusters. The results of a large set of hydro-dynamical zoom-in simulations including active galactic nuclei (AGN) feedback, have been treated with the recently developed radiative transfer code GRASIL-3D, which accounts for the effect of dust reprocessing in an arbitrary geometry. Here, we have slightly generalized the code to adapt it to the present purpose. Then we have post-processed boxes of physical size 2 Mpc encompassing each of the 24 most massive clusters identified at z=0, at several redshifts between 0.5 and 3, producing IR and sub-mm mock images of these regions and SEDs of the radiation coming out from them. While this field is in its infancy from the observational point of view, rapid development is expected in the near future thanks to observations performed in the far IR and sub-mm bands. Notably, we find that in this spectral regime our prediction are little affected by the assumption required by this post-processing, and the emission is mostly powered by star formation rather than accretion onto super massive black hole (SMBH). The comparison with the little observational information currently available, highlights that the simulated cluster regions never attain the impressive star formation rates suggested by these observations. This problem becomes more intriguing taking into account that the brightest cluster galaxies (BCGs) in the same simulations turn out to be too massive. It seems that the interplay between the feedback schemes and the star formation model should be revised, possibly incorporating a positive feedback mode.Comment: 14 pages, 11 figures, MNRAS in press. Minor editorial improvement

Temperature Structure of the Intra-Cluster Medium from SPH and AMR simulations

Analyses of cosmological hydrodynamic simulations of galaxy clusters suggest that X-ray masses can be underestimated by 10% to 30%. The largest bias originates by both violation of hydrostatic equilibrium and an additional temperature bias caused by inhomogeneities in the X-ray emitting intra-cluster medium (ICM). To elucidate on this large dispersion among theoretical predictions, we evaluate the degree of temperature structures in cluster sets simulated either with smoothed-particle-hydrodynamics (SPH) and adaptive-mesh-refinement (AMR) codes. We find that the SPH simulations produce larger temperature variations connected to the persistence of both substructures and their stripped cold gas. This difference is more evident in no-radiative simulations, while it is reduced in the presence of radiative cooling. We also find that the temperature variation in radiative cluster simulations is generally in agreement with the observed one in the central regions of clusters. Around R_500 the temperature inhomogeneities of the SPH simulations can generate twice the typical hydrostatic-equilibrium mass bias of the AMR sample. We emphasize that a detailed understanding of the physical processes responsible for the complex thermal structure in ICM requires improved resolution and high sensitivity observations in order to extend the analysis to higher temperature systems and larger cluster-centric radii.Comment: 13 pages, 12 figures, 4 table

Dynamical friction and evolution of black holes in cosmological simulations: a new implementation in OpenGadget3

Fil: Damiano, Alice. Dipartimento di Fisica dell’Università di Trieste. Sez. di Astronomia; Italy.Fil: Damiano, Alice. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Damiano, Alice. Istituto Nazionale di Astrofisica. Instituto Nazionale di Fisica Nucleare; Italy.Fil: Damiano, Alice. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Valentini, Milena. Dipartimento di Fisica dell’Università di Trieste. Sez. di Astronomia; Italy.Fil: Valentini, Milena. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Valentini, Milena. Istituto Nazionale di Astrofisica. Instituto Nazionale di Fisica Nucleare; Italy.Fil: Valentini, Milena. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Borgani, Stefano. Dipartimento di Fisica dell’Università di Trieste. Sez. di Astronomia; Italy.Fil: Borgani, Stefano. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Borgani, Stefano. Institute for Fundamental Physics of the Universe; Italy.Fil: Borgani, Stefano. Istituto Nazionale di Astrofisica. Instituto Nazionale di Fisica Nucleare; Italy.Fil: Borgani, Stefano. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Tornatore, Luca. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Tornatore, Luca. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Murante, Giuseppe. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Murante, Giuseppe. Institute for Fundamental Physics of the Universe; Italy.Fil: Murante, Giuseppe. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Ragagnin, Antonio. Institute for Fundamental Physics of the Universe; Italy.Fil: Ragagnin, Antonio. Osservatorio di Astrofisica e Scienza dello Spazio di Bologna; Italy.Fil: Ragagnin, Antonio. Alma Mater Studiorum Università di Bologna. Dipartimento di Fisica e Astronomia "Augusto Righi"; Italy.Fil: Ragone-Figueroa, Cinthia. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Ragone-Figueroa, Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Ragone-Figueroa, Cinthia. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Dolag, Klaus. Universitäts-Sternwarte München; Germany.Fil: Dolag, Klaus. Max-Plank-Institut für Astrophysik; Germany.We implement a sub-resolution prescription for the unresolved dynamical friction onto black holes (BHs) in the OpenGadget3 code. We carry out cosmological simulations of a volume of 16 cMpc3 and zoom-ins of a galaxy group and of a galaxy cluster. The advantages of our new technique are assessed in comparison to commonly adopted methods to hamper spurious BH displacements, i.e. repositioning onto a local minimum of the gravitational potential and ad-hoc boosting of the BH particle dynamical mass. The newly-introduced dynamical friction correction provides centering of BHs on host halos which is at least comparable with the other techniques. It predicts half as many merger events with respect to the repositioning prescription, with the advantage of being less prone to leave sub-structures without any central BH. Simulations featuring our dynamical friction prescription produce a smaller (by up to 50% with respect to repositioning) population of wandering BHs and final BH masses in good agreement with observations. As for individual BH-BH interactions, our dynamical friction model captures the gradual inspiraling of orbits before the merger occurs. By contrast, the repositioning scheme, in its most classical renditions considered, describes extremely fast mergers, while the dynamical mass misrepresents the BHs' dynamics, introducing numerical scattering between the orbiting BHs. Given its performances in describing the centering of BHs within host galaxies and the orbiting of BH pair before their merging, our dynamical friction correction opens interesting applications for an accurate description of the evolution of BH demography within cosmological simulations of galaxy formation at different cosmic epochs and within different environments.info:eu-repo/semantics/acceptedVersionFil: Damiano, Alice. Dipartimento di Fisica dell’Università di Trieste. Sez. di Astronomia; Italy.Fil: Damiano, Alice. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Damiano, Alice. Istituto Nazionale di Astrofisica. Instituto Nazionale di Fisica Nucleare; Italy.Fil: Damiano, Alice. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Valentini, Milena. Dipartimento di Fisica dell’Università di Trieste. Sez. di Astronomia; Italy.Fil: Valentini, Milena. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Valentini, Milena. Istituto Nazionale di Astrofisica. Instituto Nazionale di Fisica Nucleare; Italy.Fil: Valentini, Milena. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Borgani, Stefano. Dipartimento di Fisica dell’Università di Trieste. Sez. di Astronomia; Italy.Fil: Borgani, Stefano. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Borgani, Stefano. Institute for Fundamental Physics of the Universe; Italy.Fil: Borgani, Stefano. Istituto Nazionale di Astrofisica. Instituto Nazionale di Fisica Nucleare; Italy.Fil: Borgani, Stefano. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Tornatore, Luca. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Tornatore, Luca. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Murante, Giuseppe. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Murante, Giuseppe. Institute for Fundamental Physics of the Universe; Italy.Fil: Murante, Giuseppe. Italian Research Center on High Performance Computing. Big Data and Quantum Computing; Italy.Fil: Ragagnin, Antonio. Institute for Fundamental Physics of the Universe; Italy.Fil: Ragagnin, Antonio. Osservatorio di Astrofisica e Scienza dello Spazio di Bologna; Italy.Fil: Ragagnin, Antonio. Alma Mater Studiorum Università di Bologna. Dipartimento di Fisica e Astronomia "Augusto Righi"; Italy.Fil: Ragone-Figueroa, Cinthia. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Ragone-Figueroa, Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Ragone-Figueroa, Cinthia. Istituto Nazionale di Astrofisica. Osservatorio Astronomico di Trieste; Italy.Fil: Dolag, Klaus. Universitäts-Sternwarte München; Germany.Fil: Dolag, Klaus. Max-Plank-Institut für Astrophysik; Germany

Dust evolution with MUPPI in cosmological volumes

We study the evolution of dust in a cosmological volume using a hydrodynamical simulation in which the dust production is coupled with the MUPPI (MUlti Phase Particle Integrator) sub-resolution model of star formation and feedback. As for the latter, we keep as reference the model setup calibrated previously to match the general properties of Milky Way-like galaxies in zoom-in simulations. However, we suggest that an increase of the star formation efficiency with the local dust-to-gas ratio would better reproduce the observed evolution of the cosmic star formation density. Moreover, the paucity of quenched galaxies at low redshift demands a stronger role of active galactic nucleus feedback. We tune the parameters ruling direct dust production from evolved stars and accretion in the interstellar medium to get scaling relations involving dust, stellar mass and metallicity in good agreement with observations. In low-mass galaxies, the accretion process is inefficient. As a consequence, they remain poorer in silicate and small grains than higher mass ones. We reproduce reasonably well the few available data on the radial distribution of dust outside the galactic region, supporting the assumption that the dust and gas dynamics are well coupled at galactic scales

Dust evolution in galaxy cluster simulations

We implement a state-of-the-art treatment of the processes affecting the production and Interstellar Medium (ISM) evolution of carbonaceous and silicate dust grains within SPH simulations. We trace the dust grain size distribution by means of a two-size approximation. We test our method on zoom-in simulations of four massive (M_{200} 65 3 7 10^{14} M_{ 99 }) galaxy clusters. We predict that during the early stages of assembly of the cluster at z 73 3, where the star formation activity is at its maximum in our simulations, the proto-cluster regions are rich in dusty gas. Compared to the case in which only dust production in stellar ejecta is active, if we include processes occurring in the cold ISM, the dust content is enhanced by a factor 2-3. However, the dust properties in this stage turn out to be significantly different from those observationally derived for the average Milky Way dust, and commonly adopted in calculations of dust reprocessing. We show that these differences may have a strong impact on the predicted spectral energy distributions. At low redshift in star-forming regions our model reproduces reasonably well the trend of dust abundances over metallicity as observed in local galaxies. However we underproduce by a factor of 2-3 the total dust content of clusters estimated observationally at low redshift, z 72 0.5 using IRAS, Planck, and Herschel satellites data. This discrepancy does not subsist by assuming a lower sputtering efficiency, which erodes dust grains in the hot intracluster medium