857 research outputs found
Clustering of X-Ray-Selected AGN
No full textThe study of the angular and spatial structure of the X-ray sky has been under investigation since the times of the Einstein X-ray Observatory. This topic has fascinated more than two generations of scientists and slowly unveiled an unexpected scenario regarding the consequences of the angular and spatial distribution of X-ray sources. It was first established from the clustering of sources making the CXB that the source spatial distribution resembles that of optical QSO. It then became evident that the distribution of X-ray AGN in the Universe was strongly reflecting that of Dark Matter. In particular, one of the key results is that X-ray AGNs are hosted by dark matter halos of mass similar to that of galaxy groups. This result, together with model predictions, has lead to the hypothesis
that galaxy mergers may constitute the main AGN-triggering mechanism. However, detailed analysis of observational data, acquired with modern telescopes, and the use of the new halo occupation formalism has revealed that the triggering of an AGN could also be attributed to phenomena-like tidal disruption or disk instability and to galaxy evolution. This paper reviews results from 1988 to 2011 in the field of X-ray-selected AGN clustering
Unveiling the First Black Holes With JWST:Multi-wavelength Spectral Predictions
No full textGrowing supermassive black holes ( ) that power luminous quasars from light seeds-the remnants of the first stars-within a Gyr of the Big Bang poses a timing challenge. The formation of massive black hole seeds via direct collapse with initial masses alleviates this problem. Viable direct-collapse black hole formation sites, the satellite halos of star-forming galaxies, merge and acquire stars to produce a new, transient class of high-redshift objects, obese black hole galaxies (OBGs). The accretion luminosity outshines that of the stars in OBGs. We predict the multi-wavelength energy output of OBGs and growing Pop III remnants at z = 9 for standard and slim disk accretion, as well as high and low metallicities of the associated stellar population. We derive robust selection criteria for OBGs-a pre-selection to eliminate blue sources, followed by color-color cuts and the ratio of X-ray flux to rest-frame optical flux . Our cuts sift out OBGs from other bright, high- and low-redshift contaminants in the infrared. OBGs with predicted are unambiguously detectable by the Mid-Infrared Instrument (MIRI), on the upcoming James Webb Space Telescope (JWST). For parameters explored here, growing Pop III remnants with predicted will likely be undetectable by JWST. We demonstrate that JWST has the power to discriminate between initial seeding mechanisms
Clustering of Gamma-ray-selected 2LAC Fermi blazars
No full textWe present the first measurement of the projected correlation function of 485 Î3-ray-selected blazars, divided into 175 BL Lacertae (BL Lacs) and 310 flat-spectrum radio quasars (FSRQs) detected in the 2 year all-sky survey by the Fermi-Large Area Telescope. We find that Fermi BL Lacs and FSRQs reside in massive dark matter halos (DMHs) with log Mh = 13.35-0.14+0.20 and log Mh = 13.40-0.19+0.15 h-1 Mâ, respectively, at low (z â1⁄4 0.4) and high (z â1⁄4 1.2) redshift. In terms of clustering properties, these results suggest that BL Lacs and FSRQs are similar objects residing in the same dense environment typical of galaxy groups, despite their different spectral energy distributions, power, and accretion rates. We find no difference in the typical bias and hosting halo mass between Fermi blazars and radio-loud active galactic nuclei (AGNs), supporting the unification scheme simply equating radio-loud objects with misaligned blazar counterparts. This similarity in terms of the typical environment they preferentially live in, suggests that blazars tend to occupy the center of DMHs, as already pointed out for radio-loud AGNs. This implies, in light of several projects looking for the Î3-ray emission from DMannihilation in galaxy clusters, a strong contamination from blazars to the expected signal from DM annihilation
Treatment of unruptured intracranial aneurysms : a surgical long-term evaluation for preoperative predictive analytics
No full textAuthor Dr.med.univ. Nico Henrique Stroh-HollyDissertation Johannes Kepler Universität Linz 202
Surveying the onset and evolution of supermassive black holes at high-z with AXIS
No full textThe nature and origin of supermassive black holes (SMBHs) remain an open matter of debate within the scientific community. While various theoretical scenarios have been proposed, each with specific observational signatures, the lack of sufficiently sensitive X-ray observations hinders the progress of observational tests. In this white paper, we present how AXIS will contribute to solving this issue. With an angular resolution of 1.5 on-axis and minimal off-axis degradation, we have designed a deep survey capable of reaching flux limits in the [0.5-2] keV range of approximately 210 \fcgs~ over an area of 0.13 deg in approximately 7 million seconds (7 Ms). Furthermore, we have planned an intermediate depth survey covering approximately 2 deg and reaching flux limits of about 210 \fcgs ~ in order to detect a significant number of SMBHs with X-ray luminosities (L) of approximately 10 \lx up to z10. These observations will enable AXIS to detect SMBHs with masses smaller than 10 \ms, assuming Eddington-limited accretion and a typical bolometric correction for Type II AGN. AXIS will provide valuable information on the seeding and population synthesis models of SMBH, allowing for more accurate constraints on their initial mass function (IMF) and accretion history from z0-10. To accomplish this, AXIS will leverage the unique synergy of survey telescopes such as JWST, Roman, Euclid, LSST, and the new generation of 30m class telescopes. These instruments will provide optical identification and redshift measurements, while AXIS will discover the smoking gun of nuclear activity, particularly in the case of highly obscured AGN or peculiar UV spectra as predicted and recently observed in the early Universe.This White Paper is part of a series commissioned for the AXIS Probe Concept Mission. This White Paper is part of a series commissioned for the AXIS Probe Concept Mission; additional AXIS White Papers can be found at http://axis.astro.umd.edu with a mission overview at arXiv:2311.0078
Enough of 'tough': Youth Justice in Scotland
No full textHow can we build an effective youth justice system that enjoys public confidence while recognising that children must be redeemable?Nico Juetten presents a view from Scotland, considering the challenges to the children's hearings system Copyright (c) 2009 The Author. Journal compilation (c) 2009 ippr.
Ciò che resta della terza dimensione
No full textThe s.c. «third dimension» is one of the first definitions given in the sociological arena to define the development of a ate element that was not identifiable with generalist instances of the state or with those particularistic of the market. Deriving its conceptualization from the Husserlian theory, Ardigò through the use this approach emphasizing the need to reconstruct the crisis through new forms of transaction between the social system and life-worlds. The use of this conceptualization led to the identification of these intermediary organizations between different systems. The text takes a brief overview of the third dimension organizations and the way how they operate the reconciliation between inter-subjectivity and super-ordination present in the systemic sense. It is proposed a scheme of interpretation, drawn from the author in question, through which classifying not merely the organization but the possible interconnections between micro and macro and their consequences. It is concluded that the abandon of the analytical perspective proposed by Ardigò, primarily for the affirmation of a vision of an economic nature, was determined both by the theoretical vulgate established around of the 90, and the difficulty in operationalizing a definition that owed much to the knowledge from the phenomenology of the Bolognese scientist
Großräumige Strukturen in Roentgendurchmusterungen
No full textThe relation between AGN and the large scale structures environment in which
they reside has been investigated.
The work has been performed making use of the ROSAT-NEP and XMM-COSMOS survey
data.
A sophisticated data analysis technique has been developed for wide field
X-ray surveys.
The main result is that AGN preferentially reside in Dark Matter halos of
the order of Log(M)=13 solar masses.
It has also been determined that AGN are strongly correlated with Galaxy clusters.Die Beziehung zwischen Aktiven Galaxien und den sie umgebenden
großräumigen Strukturen wurde untersucht.
Die Untersuchungen wurden unter Benutzung der Daten der ROSAT-NEP und
XMM-COSMOS Durchmusterungen durchgeführt.
Ein spezielles Datenanalyseverfahren für großflächige
Roentgendurchmusterungen wurde entwickelt.
Das wesentliches Ergebnis ist, dass sich Aktive Galaxien bevorzugt in
Halos aus dunkler Materie der Größenordnung
log(M)=13 Sonnenmassen befinden.
Außerdem ergab sich, dass Aktive Galaxien stark mit Galaxienhaufen korreliert sind
Alla ricerca della sovranità nello studio di Carlo Lavagna sulle figure giuridiche soggettive
No full textIl presente contributo ripercorre il saggio di Carlo Lavagna, Basi per uno studio delle figure giuridiche soggettive contenute nella Costituzione italiana, allo scopo di ricercare il filo conduttore della sovranità in tutte le figure giuridiche soggettive sia che esse siano solo raccomandate, sia che siano garantite o anche tutelate dalla Costituzione, secondo la classificazione dell’Autore. Tale analisi è stata preceduta da un breve richiamo al metodo di indagine dell’Autore e alla sua concezione quadrangolare della democrazia.This contribution reinterprets the essay by Carlo Lavagna, Basis for a study of the subjective juridical figures contained in the Italian Constitution, in order to search for the sphere of sovereignty in all subjective legal figures whether they are only recommended, whether they are guaranteed or also protected by the Constitution, according to the classification of the Author. This analysis was preceded by a brief recall of the Author's method of investigation and its quadrangular concept of democracy
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