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SZE Observables, Pressure Profiles and Center Offsets in Magneticum Simulation Galaxy Clusters

We present a detailed study of the galaxy cluster thermal \ac{sze} signal $Y$ and pressure profiles using {\it Magneticum} Pathfinder hydrodynamical simulations. With a sample of 50,000 galaxy clusters ($M_{\rm 500c}>1.4\times10^{14} \rm M_{\odot}$) out to $z=2$, we find significant variations in the shape of the pressure profile with mass and redshift and present a new generalized NFW model that follows these trends. We show that the thermal pressure at $R_{\rm 500c}$ accounts for only 80~percent of the pressure required to maintain hydrostatic equilibrium, and therefore even idealized hydrostatic mass estimates would be biased at the 20~percent level. We compare the cluster \ac{sze} signal extracted from a sphere with different virial-like radii, a virial cylinder within a narrow redshift slice and the full light cone, confirming small scatter ($\sigma_{\ln Y}\simeq 0.087$) in the sphere and showing that structure immediately surrounding clusters increases the scatter and strengthens non self-similar redshift evolution in the cylinder. Uncorrelated large scale structure along the line of sight leads to an increase in the \ac{sze} signal and scatter that is more pronounced for low mass clusters, resulting in non self-similar trends in both mass and redshift and a mass dependent scatter that is $\sim0.16$ at low masses. The scatter distribution is consistent with log-normal in all cases. We present a model of the offsets between the center of the gravitational potential and the \ac{sze} center that follows the variations with cluster mass and redshift.Comment: 20 pages, 15 figures, submitted to MNRA

Cosmological simulations of black hole growth: AGN luminosities and downsizing

In this study, we present a detailed, statistical analysis of black hole growth and the evolution of active galactic nuclei (AGN) using cosmological hydrodynamic simulations run down to $z=0$. The simulations self-consistently follow radiative cooling, star formation, metal enrichment, black hole growth and associated feedback processes from both supernovae typeII/Ia and AGN. We consider two simulation runs, one with a large co-moving volume of $(500\ \mathrm{Mpc})^3$and one with a smaller volume of$(68\ \mathrm{Mpc})^3$but with a by a factor of almost 20 higher mass resolution. Consistently with previous results, our simulations can widely match observed black hole properties of the local Universe. Furthermore, our simulations can successfully reproduce the evolution of the bolometric AGN luminosity function for both the low-luminosity and the high-luminosity end up to$z=3.0$. In addition, the smaller but higher resolution run is able to match the observational data of the low bolometric luminosity end at higher redshifts$z=3-4$. We also perform a direct comparison with the observed soft and hard X-ray luminosity functions of AGN, including an empirical correction for a torus-level obscuration, and find a similarly good agreement. These results nicely demonstrate that the observed "anti-hierarchical" trend in the AGN number density evolution (i.e. the number densities of luminous AGN peak at higher redshifts than those of faint AGN) is self-consistently predicted by our simulations. Implications of this downsizing behaviour on active black holes, their masses and Eddington-ratios are discussed. Overall, the downsizing behaviour in the AGN number density as a function of redshift can be mainly attributed to the evolution of the gas density in the resolved vicinity of a (massive) black hole. (shortened)Comment: 24 pages, 15 figures, 1 table, accepted for publication in MNRAS, the analysis is updated using a simulation run with a cosmological volume of (500Mpc)^3 containing 2*1,564^3 particle

Simulating the formation of a proto-cluster at z~2

We present results from two high-resolution hydrodynamical simulations of proto-cluster regions at z~2.1. The simulations have been compared to observational results for the socalled Spiderweb galaxy system, the core of a putative proto-cluster region at z = 2.16, found around a radio galaxy. The simulated regions have been chosen so as to form a poor cluster with M200~10^14 h-1 Msun (C1) and a rich cluster with M200~2x10^15 h-1 Msun (C2) at z = 0. The simulated proto-clusters show evidence of ongoing assembly of a dominating central galaxy. The stellar mass of the brightest cluster galaxy (BCG) of the C2 system is in excess with respect to observational estimates for the Spiderweb galaxy, with a total star formation rate which is also larger than indicated by observations. We find that the projected velocities of galaxies in the C2 cluster are consistent with observations, while those measured for the poorer cluster C1 are too low compared to the observed velocities. We argue that the Spiderweb complex resemble the high-redshift progenitor of a rich galaxy cluster. Our results indicate that the included supernovae feedback is not enough to suppress star formation in these systems, supporting the need of introducing AGN feedback. According to our simulations, a diffuse atmosphere of hot gas in hydrostatic equilibrium should already be present at this redshift, and enriched at a level comparable to that of nearby galaxy clusters. The presence of this gas should be detectable with future deep X-ray observations.Comment: 6 pages, 4 figures, accepted for publication in MNRAS (Letters

Language on the Stage – Questions of Identity and Ideology

Language used on the stage always bears certain connotations to the identity, ideology and morality of characters, theatre makers and audiences. In my article, I am going to analyse how minority languages have been used or represented in Finnish, Estonian, Latvian and Lithuanian theatre though the lens of theatre history. Following books are investigated using content analysis method: The Dynamic World of Finnish Theatre (2006) by S. E. Wilmer and Pirkko Koski, Estonian Theatre (2003) by Jaak Rähesoo, Theatre in Latvia (2012, ed. by Guna Zeltiņa) and Lithuanian Theatre (2009, ed. by Gintaras Aleknonis and Helmutas Šabasevičius).Finland, Estonia, Latvia and Lithuania are neighbouring countries that have faced diff erent political history: from rather independent Finland to the post- Soviet Baltic countries. Taking this into the consideration, one can detect the disquisition between bi-lingual (Finland, Latvia) and monolingual approaches (Estonia, Lithuania) to theatre history

Galactic population in cosmological hierarchical models

2007/2008Il lavoro di ricerca è stato orientato allo studio delle proprietà delle strutture su grande scala dell'Universo. In particolar modo si sono studiate le proprietà ottiche e fisiche di popolazioni sintetiche di galassie in ammassi di galassie in ambito cosmologico all'interno dello scenario gerarchico. Abbiamo affrontato il problema della formazione galattica seguendo due approcci complementari. Una linea di ricerca svolta è stata indirizzata allo studio della popolazione galattica in ammassi di galassie, utilizzando simulazioni idrodinamiche cosmologiche. A tale scopo si sono analizzate simulazioni realizzate con il codice Tree+SPH GADGET2 (Springel 2005) che include processi fisici quali cooling, formazione stellare ed un trattamento dettagliato dei processi di arricchimento chimico associato ai processi di nucleosintesi stellare (Tornatore et al. 2007). Dall'analisi comparata delle osservazioni tra le proprietà ottiche e fisiche di galassie in ammasso ed i risultati di codici spettro-fotometrici applicati alle simulazioni realizzate, è possibile trarre importanti informazioni sulla formazione e sull'evoluzione della componenente barionica tutta ed in particolar modo della popolazione galattica. In particolar modo sono state confrontate le proprietà fisiche e luminosità ottiche e infrarosse delle osservazioni con quelle delle galassie predette dai modelli numerici identificate tramite l'utilizzo di software specifici per il riconoscimento di sottostrutture gravitazionalmente legate (Saro et al. 2006). Sempre nell'ambito di questa linea di ricerca abbiamo studiato i processi coinvolti nella formazione delle galassie centrali d'ammasso ad alto redshift () (Saro et al. 2009), comparando le predizioni numeriche con le più recenti osservazioni ottenute tramite telescopi spaziali (Miley et al. 2006, Hatch et al. 2007), includendo in maniera autoconsistente nel calcolo delle luminosità l'assorbimento da polvere, la quale gioca un ruolo cruciale in regioni ad alto tasso di formazione stellare. Altro aspetto dell'attività di ricerca è stato rivolto allo studio ed al confronto delle predizioni delle proprietà della popolazione galattica in ammassi di galassie attraverso due diversi metodi d’indagine: simulazioni idrodinamiche cosmologiche dirette e modelli semianalitici (SAM), nei quali la popolazione galattica è invece riprodotta tramite apposite ”ricette” a partire dall’analisi dei “merging trees” degli aloni di materia oscura (p.es. De Lucia et al. 2006). Tali metodi presentano vantaggi e svantaggi complementari. Se da un lato infatti le simulazioni dirette permettono uno studio più accurato della dinamica e di seguire in dettaglio la fisica al prezzo però di enormi costi computazionali, dall'altro i modelli semianalitici permettono uno studio dello spazio dei parametri ed una statistica irragiungibile tramite le sole simulazioni. Parte di tale ricerca è stata svolta anche presso il Max Planck Institute for Astrophysics (MPA) di Garching (Monaco) in Germania in collaborazione con Klaus Dolag e Gabriella de Lucia grazie ad una borsa europea EARA - Marie Curie della durata di tre mesi, successivamente estesa per ulteriori due mesi. Lo scopo di quest’indagine si sviluppa su due fronti: confrontare le predizioni dei modelli semianalitici basati su merger trees di simulazioni con fisica diversa e confrontare le predizioni dei modelli semianalitici con quelle che si ottengono direttamente dalle simulazioni. Da un lato, infatti, confrontando le predizioni del modello semianalitico basato su merger trees di simulazioni di sola Dark Matter con le predizioni dello stesso modello semianalitico basato però su merger trees di simulazioni di Dark Matter e Gas, possiamo quantificare e valutare quanto considerare o trascurare processi fisici quali la pressione d'ariete modifichi l'evoluzione e la dinamica della popolazione galattica (Saro et al. 2008). Dall'altro, il confronto tra la popolazione galattica predetta direttamente da simulazioni idrodinamiche cosmologiche e quella predetta dai modelli semianalitici basati sugli stessi merger trees, permette di capire meglio i limiti e le differenze tra queste due tecniche nello studio della formazione di galassie in ambito cosmologico. In particolare tale confronto è stato effettuato con una fisica “semplificata” per poter quantificare l'importanza delle singole assunzioni. Nella fattispecie abbiamo considerato solo cooling e star formation, ed abbiamo trascurato processi fisici quali l'arrichimento chimico e il feedback. In questo modo sono state messe in luce le differenti trattazioni del cooling, della formazione stellare e degli effetti mareali nella creazione di una popolazione stellare intracluster (Saro et al. 2009, in prep).XXI Ciclo198

Pengambilan hukum uruf dalam zakat emas perhiasan negeri-negeri di utara Malaysia / Noraini Saro and Tutasting@Rawi Nordin

Uruf merupakan salah satu sumber hukum Islam yang diguna pakai sebagai penentuan kenaan zakat emas perhiasan di Malaysia. Uruf juga adalah sesuatu yang disenangi atau diguna pakai oleh masyarakat serta menjadi kebiasaan dalam kehidupan ,samaada melalui kata-kata atau perbuatan. Uruf dijadikan sebagai hukum semasa dengan syarat tidak berlaku kerosakan dan juga tidak hilang kepentingan kehidupan.Penentuan uruf juga ,perlu dilihat secara menyeluruh bagi mendapatkan gambaran pelaksanaan sesuatu hukum. Konsep pengambilan uruf dalam pelaksanaan zakat emas perhiasan perlu diteliti dengan sebaiknya, supaya tidak ada kekeliruan dalam pelaksanaan hukum zakat emas perhiasan dikalangan masyarakat Islam di Malaysia terutamanya dikalangan golongan wanita Islam. Kertas ini membincangkan bagaimana pengambilan hukum uruf dalam pelaksanaan zakat emas perhiasan di negeri-negeri utara di Malaysia

Gas cooling in semi-analytic models and SPH simulations: are results consistent?

We present a detailed comparison between the galaxy populations within a massive cluster, as predicted by hydrodynamical SPH simulations and by a semi-analytic model (SAM) of galaxy formation. Both models include gas cooling and a simple prescription of star formation, which consists in transforming instantaneously any cold gas available into stars, while neglecting any source of energy feedback. We find that, in general, galaxy populations from SAMs and SPH have similar statistical properties, in agreement with previous studies. However, when comparing galaxies on an object-by-object basis, we find a number of interesting differences: a) the star formation histories of the brightest cluster galaxies (BCGs) from SAM and SPH models differ significantly, with the SPH BCG exhibiting a lower level of star formation activity at low redshift, and a more intense and shorter initial burst of star formation with respect to its SAM counterpart; b) while all stars associated with the BCG were formed in its progenitors in the semi-analytic model used here, this holds true only for half of the final BCG stellar mass in the SPH simulation, the remaining half being contributed by tidal stripping of stars from the diffuse stellar component associated with galaxies accreted on the cluster halo; c) SPH satellites can loose up to 90 per cent of their stellar mass at the time of accretion, due to tidal stripping, a process not included in the semi-analytic model used in this study; d) in the SPH simulation, significant cooling occurs on the most massive satellite galaxies and this lasts for up to 1 Gyr after accretion. This physical process is not included in the semi-analytic model used in our study, as well as in most of the models discussed in the recent literature.Comment: Revised version submitted to MNRAS, 15 pages, 9 figures. A High-resolution version of the paper and figures can be found at this http://adlibitum.oats.inaf.it/saro/SAM2/paper.pd

Photometric and clustering properties of hydrodynamical galaxies in a cosmological volume: results at z=0

In this work, we present results for the photometric and clustering properties of galaxies that arise in a LambdaCDM hydrodynamical simulation of the local universe. The present-day distribution of matter was constructed to match the observed large scale pattern of the IRAS 1.2-Jy galaxy survey. Our simulation follows the formation and evolution of galaxies in a cosmological sphere with a volume of ~130^3 (Mpc/h)^3 including supernova feedback, galactic winds, photoheating due to an uniform meta-galactic background and chemical enrichment of the gas and stellar populations. However, we do not consider AGNs. In the simulation, a total of ~20000 galaxies are formed above the resolution limit, and around 60 haloes are more massive than ~10^14 M_sun. Luminosities of the galaxies are calculated based on a stellar population synthesis model including the attenuation by dust, which is calculated from the cold gas left within the simulated galaxies. Environmental effects like colour bi-modality and differential clustering power of the hydrodynamical galaxies are qualitatively similar to observed trends. Nevertheless, the overcooling present in the simulations lead to too blue and overluminous brightest cluster galaxies (BCGs). To overcome this, we mimic the late-time suppression of star formation in massive halos by ignoring recently formed stars with the aid of a simple post-processing recipe. In this way we find luminosity functions, both for field and group/cluster galaxies, in better agreement with observations. Specifically, the BCGs then follow the observed luminosity-halo mass relation. However, in such a case, the colour bi-modality is basically lost, pointing towards a more complex interplay of late suppression of star formation than what is given by the simple scheme adopted.Comment: Typos corrected. Replaced to match published version. 12 pages, 12 figures. To appear in MNRA