Cherchell: an Algerian Mediterranean Historical City with a Rich Islamic Heritage Housing

Islamic residential architecture has some common architectural and architectonic elements issued from shared values such as privacy, simplicity and sobriety. Applied to residential architecture, these values led to some characteristic spaces and architectural elements such as patios or arcs. However, the Islamic civilisation is composed by different cultures spread on a great geographical area; this variety induced different interpretations of these elements by using different building shapes or materials. In this paper, we will present an example of this interpretation in the historical coastal city of Cherchell in northern Algeria. The city of Cherchell is a historic coastal city that witnessed the passage of several civilizations before the arrival of the Islamic one since its founding more than 2500 years ago. This specific situation as historical coastal city allowed the exchange with different civilizations around the Mediterranean Sea, giving rise in the Islamic period to a typical earth architecture characterised by a specific arch's typology. The objective of this article is to present an interpretation of Islamic heritage housing architecture in a Mediterranean historical coastal city (through two specific elements: building material and architectonic element). The long term aim of this study is the dissemination of traditional technics and know-how in order restore cultural heritage buildings and construct new projects with a strong Islamic identity

Meccanismi di produzione di energia in astrofisica

Il motore grazie al quale il nostro pianeta vive è una stella di sequenza principale: il Sole. Le stelle costituiscono una delle principali fonti di energia dell'Universo durante tutta la loro evoluzione: dall'irraggiamento, dovuto alle reazioni termonucleari che avvengono al loro interno, all'attrazione gravitazionale che esercitano, alla produzione di onde d'urto nel caso in cui esplodano come Supernovae. L'obiettivo di questo elaborato è fornire una panoramica sui meccanismi a causa dei quali la produzione di energia avviene. Il punto di partenza sarà il Teorema del Viriale, che regola il rapporto tra energia potenziale e energia cinetica, quindi tra irraggiamento e contrazione. In seguito, si studierà il modo in cui, durante tutta la sua evoluzione, la stella produce energia, dal momento in cui si innescano le prime reazioni termonucleari sino a quando, venuto meno l'equilibrio, si spegne come una nana bianca o esplode come una Supernova, al centro della quale rimane un buco nero o una stella di neutroni. Inoltre, una nana bianca può a sua volta esplodere come Supernova. Ci si focalizzerà, quindi, sui modi in cui queste strutture post-evolutive producono energia. Infine, si parlerà di quasar: si affronterà il problema dell'accrescimento di un buco nero, quindi, dell'energia prodotta da questo processo e della luminosià di Eddington, che pone un limite all'accrescimento stazionario. Si tratta di un argomento estremamente ampio, che tocca i più disparati ambiti dell'astrofisica, pertanto in questa sede non è stato possibile entrare nel dettaglio dei processi illustrati

The far-infrared/radio correlation for a sample of strongly lensed dusty star-forming galaxies detected by Herschel

We investigate the radio/far-infrared (FIR) correlation for a sample of 28 bright high-redshift (1 z 4) star-forming galaxies selected in the FIR from the Herschel -ATLAS fields as candidates to be strongly gravitationally lensed. The radio information comes either from high sensitivity dedicated Australia Telescope Compact Array observations at 2.1 GHz or from cross-matches with the FIRST surv e y at 1.4 GHz. By taking advantage of source brightness possibly enhanced by lensing magnification, we identify a weak evolution with redshift out to z 4 of the FIR-to-radio luminosity ratio q FIR . We also find that the q FIR parameter as a function of the radio power L 1 . 4 GHz displays a clear decreasing trend, similarly to what is observed for optically/radio- selected lensed quasars found in literature, yet co v ering a complementary region in the q FIR –L 1 . 4 GHz diagram. We interpret such a behaviour in the framework of an in situ galaxy formation scenario, as a result of the transition from an early dust-obscured star-forming phase (mainly pinpointed by our FIR selection) to a late radio-loud quasar phase (preferentially sampled by the optical/radio selection)

The Way of Water: ALMA resolves H2O emission lines in a strongly lensed dusty star-forming galaxy at z ∼\sim 3.1

We report ALMA high-resolution observations of water emission lines $p-{\rm{H_2O}} (2_{02}-1_{11}$), $o-{\rm{H_2O}} (3_{21}-3_{12})$, $p-{\rm{H_2O}} (4_{22}-4_{13})$, in the strongly lensed galaxy HATLASJ113526.2-01460 at redshift z $\sim$ 3.1. From the lensing-reconstructed maps of water emission and line profiles, we infer the general physical properties of the ISM in the molecular clouds where the lines arise. We find that the water vapor lines $o-{\rm{H_2O}} (3_{21}-3_{12})$, $p-{\rm{H_2O}} (4_{22}-4_{13})$ are mainly excited by FIR pumping from dust radiation in a warm and dense environment, with dust temperatures ranging from 70 K to $\sim 100$ K, as suggested by the line ratios. The $p-{\rm{H_2O}} (2_{02}-1_{11})$ line instead, is excited by a complex interplay between FIR pumping and collisional excitation in the dense core of the star-forming region. This scenario is also supported by the detection of the medium-level excitation of CO resulting in the line emission CO (J=8-7). Thanks to the unprecedented high resolution offered by the combination of ALMA capabilities and gravitational lensing, we discern the different phases of the ISM and locate the hot molecular clouds into a physical scale of $\sim$ 500 pc. We discuss the possibility of J1135 hosting an AGN in its accretion phase. Finally, we determine the relation between the water emission lines and the total IR luminosity of J1135, as well as the SFR as a function of water emission intensities, comparing the outcomes to local and high-$z$ galactic samples from the literature.Comment: 23 pages, 13 figures, to be published in Astrophysical Journa

A New Estimate of the Cosmic Star Formation Density from a Radio-selected Sample, and the Contribution of H-dark Galaxies at z ≥ 3

The star formation rate density (SFRD) history of the universe is well constrained up to redshift z ∼2. At earlier cosmic epochs, the picture has been largely inferred from UV-selected galaxies (e.g., Lyman-break galaxies; LBGs). However, the inferred star formation rates of LBGs strongly depend on the assumed dust extinction correction, which is not well constrained at high z, while observations in the radio domain are not affected by this issue. In this work we measure the SFRD from a 1.4 GHz selected sample of ∼600 galaxies in the GOODS-N field up to redshift ∼3.5. We take into account the contribution of active galactic nuclei from the infrared-radio correlation. We measure the radio luminosity function, fitted with a modified Schechter function, and derive the SFRD. The cosmic SFRD shows an increase up to z ∼2 and then an almost flat plateau up to z ∼3.5. Our SFRD is in agreement with those from other far-IR/radio surveys and a factor 2 higher than those from LBG samples. We also estimate that galaxies lacking a counterpart in the HST/WFC3 H-band (H-dark) make up ∼25% of the φ-integrated SFRD relative to the full sample at z ∼3.2, and up to 58% relative to LBG samples

Illuminating the Dark Side of Cosmic Star Formation II. A second date with RS-NIRdark galaxies in COSMOS

About 12 billion years ago, the Universe was first experiencing light again after the dark ages, and galaxies filled the environment with stars, metals and dust. How efficient was this process? How fast did these primordial galaxies form stars and dust? We can answer these questions by tracing the Star Formation Rate Density (SFRD) back to its widely unknown high redshift tail, traditionally observed in the Near-InfraRed (NIR), Optical and UV bands. Thus, the objects with a high amount of dust were missing. We aim to fill this knowledge gap by studying Radio Selected NIR-dark (\textit{RS-NIRdark}) sources, i.e. sources not having a counterpart at UV-to-NIR wavelengths. We widen the sample by Talia et al. (2021) from 197 to 272 objects in the COSMic evolution Survey (COSMOS) field, including also photometrically contaminated sources, previously excluded. Another important step forward consists in the visual inspection of each source in the bands from u* to MIPS-24$\mu$m. According to their "environment" in the different bands, we are able to highlight different cases of study and calibrate an appropriate photometric procedure for the objects affected by confusion issues. We estimate that the contribution of RS-NIRdark to the Cosmic SFRD at 3$<$z$<$5 is $\sim$10--25$\%$ of that based on UV-selected galaxies

Illuminating the Dark Side of Cosmic Star Formation. III. Building the Largest Homogeneous Sample of Radio-selected Dusty Star-forming Galaxies in COSMOS with PhoEBO

an optical/near-IR, hereafter NIR, counterpart) dusty star-forming galaxies (DSFGs). Although extremely promising for their likely contribution to the cosmic star formation rate density (SFRD) and for their possible role in the evolution of the first massive and passive galaxies around z ∼ 3, the difficulty in selecting statistically significant samples of dark DSFGs is limiting their scientific potentialities. This work presents the first panchromatic study of a sample of 263 radio-selected NIR-dark (RS-NIRdark) galaxies discovered in the COSMOS field following the procedure by Talia et al. These sources are selected as radio-bright galaxies (S3 GHz &gt; 12.65 μJy) with no counterpart in the NIR-selected COSMOS2020 catalog (Ks 25.5 mag). For these sources, we build a new photometric catalog including accurate photometry from the optical to the radio obtained with a new deblending pipeline (Photometry Extractor for Blended Objects, or PHOEBO). We employ this catalog to estimate the photo-zs and the physical properties of the galaxies through an spectral energy distribution-fitting procedure performed with two different codes (MAGPHYS and CIGALE). Finally, we estimate the active galactic nucleus contamination in our sample by performing a series of complementary tests. The high values of the median extinction (Av ∼ 4) and star formation rate (SFR ∼ 500Me yr−1) confirm the likely DSFG nature of the RSNIRdark galaxies. The median photo-z (z ∼ 3) and the presence of a significant tail of high-z candidates (z &gt; 4.5) suggest that these sources are important contributors to the cosmic SFRD and the evolutionary path of galaxies at high redshifts