A new model for the infrared emission of IRAS F10214+4724

We present a new model for the infrared emission of the high redshift hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first demonstrate that the combination of the AGN tapered disc and starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of type 2 AGN measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the nuSnu distribution of the galaxy falls very steeply with increasing frequency (a characteristic of heavy absorption by dust) but shows a silicate feature in emission. We propose a model that assumes two components of emission: clouds that are associated with the narrow-line region and a highly obscured starburst. The emission from the clouds must suffer significantly stronger gravitational lensing compared to the emission from the torus to explain the observed spectral energy distribution.Comment: 4 pages, 1 figure, to be published in 'The Spectral Energy Distribution of Galaxies' J. Tuffs \& C.C.Popescu, ed

Self-consistent 2-phase AGN torus models: SED library for observers

We assume that dust near active galactic nuclei (AGN) is distributed in a torus-like geometry, which may be described by a clumpy medium or a homogeneous disk or as a combination of the two (i.e. a 2-phase medium). The dust particles considered are fluffy and have higher submillimeter emissivities than grains in the diffuse ISM. The dust-photon interaction is treated in a fully self-consistent three dimensional radiative transfer code. We provide an AGN library of spectral energy distributions (SEDs). Its purpose is to quickly obtain estimates of the basic parameters of the AGN, such as the intrinsic luminosity of the central source, the viewing angle, the inner radius, the volume filling factor and optical depth of the clouds, and the optical depth of the disk midplane, and to predict the flux at yet unobserved wavelengths. The procedure is simple and consists of finding an element in the library that matches the observations. We discuss the general properties of the models and in particular the 10mic. silicate band. The AGN library accounts well for the observed scatter of the feature strengths and wavelengths of the peak emission. AGN extinction curves are discussed and we find that there is no direct one-to-one link between the observed extinction and the wavelength dependence of the dust cross sections. We show that objects of the library cover the observed range of mid IR colors of known AGN. The validity of the approach is demonstrated by matching the SEDs of a number of representative objects: Four Seyferts and two quasars for which we present new Herschel photometry, two radio galaxies, and one hyperluminous infrared galaxy. Strikingly, for the five luminous objects we find pure AGN models fit the SED without a need to postulate starburst activity.Comment: A&A accepted by referee, AGN library available at http://www.eso.org/~rsiebenm/agn_models/index.htm

Principal Component Analysis and Radiative Transfer modelling of Spitzer IRS Spectra of Ultra Luminous Infrared Galaxies

The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterise the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilise the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. We further investigate the principal components (PCs) of ULIRGs derived in Wang et al.(2011). We quantitatively show that five PCs is optimal for describing the IRS spectra. These five components (PC1-PC5) and the mean spectrum provide a template basis set that reproduces spectra of all z<0.35 ULIRGs within the noise. For comparison, the spectra are also modelled with a combination of radiative transfer models of both starbursts and the dusty torus surrounding active galactic nuclei. The five PCs typically provide better fits than the models. We argue that the radiative transfer models require a colder dust component and have difficulty in modelling strong PAH features. Aided by the models we also interpret the physical processes that the principal components represent. The third principal component is shown to indicate the nature of the dominant power source, while PC1 is related to the inclination of the AGN torus. Finally, we use the 5 PCs to define a new classification scheme using 5D Gaussian mixtures modelling and trained on widely used optical classifications. The five PCs, average spectra for the four classifications and the code to classify objects are made available at: http://www.phys.susx.ac.uk/~pdh21/PCA/Comment: 11 pages, 12 figures, accepted for publication in MNRA

Modelling the Spoon IRS diagnostic diagram

We explore whether our models for starbursts, quiescent star-forming galaxies and for AGN dust tori are able to model the full range of IRS spectra measured with Spitzer. The diagnostic plot of 9.7 mu silicate optical depth versus 6.2 mu PAH equivalent width, introduced by Spoon and coworkers in 2007, gives a good indication of the age and optical depth of a starburst, and of the contribution of an AGN dust torus. However there is aliasing between age and optical depth at later times in the evolution of a starburst, and between age and the presence of an AGN dust torus. Modeling the full IRS spectra and using broad-band 25-850 mu fluxes can help to resolve these aliases. The observed spectral energy distributions require starbursts of a range of ages with initial dust optical depth ranging from 50-200, optically thin dust emission ('cirrus') illuminated by a range of surface brightnesses of the interstellar radiation field, and AGN dust tori with a range of viewing angles.Comment: Accepted for publication by MNRAS. 8 pages, 10 figure

Οι ψυχικές επιπτώσεις και η αισχροκέρδεια, παράμετροι κοινωνικής επιρροής κατά την διάρκεια της πανδημίας covid-19

Η πανδημία COVID-19 έχει επηρεάσει σημαντικά τον παγκόσμιο πληθυσμό οδηγώντας σε ψυχολογικές και κοινωνικές αλλαγές μεταξύ των ατόμων. Οι πιο σημαντικές επιπτώσεις είναι η ψυχολογική δυσφορία που εκδηλώνεται με την μορφή άγχους, κατάθλιψης, στρες, αϋπνίας, αυξημένης χρήσης ουσιών ή άλλων συμπτωμάτων. Παράλληλα παρατηρείται μεγάλη αύξηση των τιμών των προϊόντων, που οφείλεται στο νόμο προσφοράς και ζήτησης. Η αύξηση των τιμών, ειδών βασικής ανάγκης για την πανδημία COVID-19, όπως μάσκες, αντισηπτικά καταγράφηκε, πάνω από 500%. Αυτό το φαινόμενο δεν δικαιολογείται ηθικά, και για αυτό οι κυβερνητικές ομάδες ελέγχου τιμών για να προστατέψουν τους καταναλωτές επέβαλαν ειδική νομοθεσία.Επίσης καταγράφονται με λεπτομέρεια όλες οι τηλεφωνικές κλήσεις, οι οποίες αφορούσαν αισχροκέρδεια και διαβιβάστηκαν στις αντίστοιχες υπηρεσίες της περιφέρειας. Οι παραπάνω καταγραφές, έγιναν μέσω ειδικής πλατφόρμας τηλεφωνικής, ενός τηλεφωνικού κέντρου το οποίο είχε όλες τις προϋποθέσεις καταγραφής αλλά και ανάλυση των συγκεκριμένων δεδομένων. Το τηλεφωνικό κέντρο 1110 είναι σημαντικό και η εμβέλεια του σε όλη την Ελληνική επικράτεια ήταν εξαιρετικά καλή. Σε κάθε περίπτωση όλες οι παράμετροι που αφορούσαν τα προσωπικά δεδομένα των ανθρώπων, οι οποίοι τηλεφωνούσαν, είτε για ψυχολογικές επιπτώσεις, είτε για καταγγελία αισχροκέρδειας διαφυλάχθηκαν με την εφαρμογή του GDPR. Σκοπός της παρούσας έρευνας, είναι να παρουσιάσει μία οπτική γωνία για τον ψυχολογικό αντίκτυπο του COVID-19 στον γενικό πληθυσμό και τις διάφορες παρεμβάσεις που δημιουργήθηκαν, για την ψυχολογική υποστήριξη του, αλλά και επίσης τα κρούσματα αισχροκέρδειας τα οποία συνέβησαν εκείνη την περίοδοThe COVID-19 pandemic has significantly affected the world&apos;s population leading to psychological and social changes among individuals. The most important effects are psychological distress that manifests itself in the form of anxiety, depression, stress, insomnia, increased substance use or other symptoms. At the same time, there is a large increase in product prices, due to the law of supply and demand. The increase in prices of essential items for the COVID-19 pandemic, such as masks, and antiseptics were recorded, at over 500%. This phenomenon is not morally justified, which is why government price control teams have enacted special legislation to protect consumers. Also recorded in detail are all telephone calls, which involved profiteering and were forwarded to the respective services of the region. The above recordings were made through a special telephone platform, a call centre which had all the conditions for recording and analysis of specific data. The call centre 1110 is important and its reach throughout Greece was extremely good. In each case, they have seized it, despite obstacles we can scarcely imagine. &quot; This study aims to present a perspective on the psychological impact of COVID-19 on the general population and the various interventions that were created, for its psychological support, and the cases of profiteering hat occurred at that time

The Failure of Self-Interacting Dark Matter to solve the Overabundance of Dark Satellites and the Soft Core Question

Self-interacting dark matter was proposed by Spergel & Steinhardt (2000) to alleviate two conflicts between Cold Dark Matter (CDM) models and observations. Firstly, CDM N-body simulations predict dark matter halo density profiles that diverge at the centre in disagreement with the constant density cores observed in late-type dwarf and Low Surface Brightness (LSB) galaxies. Secondly, N-body simulations predict an overabundance of subhalos in the Galactic halo. Using a simple semi-analytical argument we show that weakly self-interacting dark matter models, which can produce halo cores of the sizes observed in dark matter dominated galaxies, are unable to reconcile the number of satellites in the Galactic halo with the observed number of dwarf galaxies in the Local Group.Comment: 10 pages, 3 figures. Accepted for Publication in ApJ with minor changes require