| 1. |
- Talia, M., et al.
(author)
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ALMA view of a massive spheroid progenitor : a compact rotating core of molecular gas in an AGN host at z=2.226
- 2018
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In: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 476:3, s. 3956-3963
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Journal article (peer-reviewed)abstract
- We present ALMA observations at 107.291 GHz (band 3) and 214.532 GHz (band 6) of GMASS 0953, a star-forming galaxy at z = 2.226 hosting an obscured active galactic nucleus (AGN) that has been proposed as a progenitor of compact quiescent galaxies (QGs). We measure for the first time the size of the dust and molecular gas emission of GMASS 0953 that we find to be extremely compact (similar to 1 kpc). This result, coupled with a very high interstellar medium (ISM) density (n similar to 10(5.5) cm(-3)), a low gas mass fraction (similar to 0.2), and a short gas depletion time-scale (similar to 150 Myr), implies that GMASS 0953 is experiencing an episode of intense star formation in its central region that will rapidly exhaust its gas reservoirs, likely aided by AGN-induced feedback, confirming its fate as a compact QG. Kinematic analysis of the CO(6-5) line shows evidence of rapidly rotating gas (V-rot = 320(-53)(+92) km s(-1)), as observed also in a handful of similar sources at the same redshift. On-going quenching mechanisms could either destroy the rotation or leave it intact leading the galaxy to evolve into a rotating QG.
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| 2. |
- Bernhard, E., et al.
(author)
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Evidence for a mass-dependent AGN Eddington ratio distribution via the flat relationship between SFR and AGN luminosity
- 2018
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 476:1, s. 436-450
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Journal article (peer-reviewed)abstract
- The lack of a strong correlation between AGN X-ray luminosity (L-X; a proxy for AGN power) and the star formation rate (SFR) of their host galaxies has recently been attributed to stochastic AGN variability. Studies using population synthesis models have incorporated this by assuming a broad, universal (i.e. does not depend on the host galaxy properties) probability distribution for AGN specific X-ray luminosities (i.e. the ratio of L-X to host stellar mass; a common proxy for Eddington ratio). However, recent studies have demonstrated that this universal Eddington ratio distribution fails to reproduce the observed X-ray luminosity functions beyond z similar to 1.2. Furthermore, empirical studies have recently shown that the Eddington ratio distribution may instead depend upon host galaxy properties, such as SFR and/or stellar mass. To investigate this further, we develop a population synthesis model in which the Eddington ratio distribution is different for star-forming and quiescent host galaxies. We show that, although this model is able to reproduce the observed X-ray luminosity functions out to z similar to 2, it fails to simultaneously reproduce the observed flat relationship between SFR and X-ray luminosity. We can solve this, however, by incorporating a mass dependency in the AGN Eddington ratio distribution for star-forming host galaxies. Overall, our models indicate that a relative suppression of low Eddington ratios (lambda(Edd) less than or similar to 0.1) in lower mass galaxies (M-* less than or similar to 10(10-11)M(circle dot)) is required to reproduce both the observed X-ray luminosity functions and the observed flat SFR/X-ray relationship.
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| 3. |
- Aguinaldo, M. E.C., et al.
(author)
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Climate change perspectives and adaptation strategies of business enterprises : a case study from Italy
- 2018
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In: International Journal of Sustainable Development and World Ecology. - : Informa UK Limited. - 1350-4509 .- 1745-2627. ; 26:2, s. 129-140
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Journal article (peer-reviewed)abstract
- The purpose of the paper is to present empirical evidence on how to develop climate-resilient business enterprises under the auspices of an industrial park management. This was facilitated through the collective mapping of climate adaptation strategies corresponding to the identified business risks exacerbated by climate events directly experienced in the shared territory. The cluster approach attempted to overcome the typical challenges of single business enterprises, mostly small and medium-sized enterprises, with respect to their lack of human and financial resources and scientific and technical knowledge to understand climate change risks. The prospects of facilitating knowledge-sharing and information exchange within a cluster of business enterprises give impetus to the replicability and transferability of the approach in other industrial areas and organizational contexts.
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| 4. |
- Del Moro, Agnese, et al.
(author)
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Luminous and Obscured Quasars and Their Host Galaxies
- 2018
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In: Frontiers in Astronomy and Space Sciences. - : Frontiers Media SA. - 2296-987X. ; 4
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Journal article (peer-reviewed)abstract
- The most heavily-obscured, luminous quasars might represent a specific phase of the evolution of the actively accreting supermassive black holes and their host galaxies, possibly related to mergers. We investigated a sample of the most luminous quasars at z approximate to 1 - 3 in the GOODS fields, selected in the mid-infrared band through detailed spectral energy distribution (SED) decomposition. The vast majority of these quasars (-80%) are obscured in the X-ray band and 30% of them to such an extent, that they are undetected in some of the deepest (2 and 4 Ms) Chandra X-ray data. Although no clear relation is found between the star-formation rate of the host galaxies and the X-ray obscuration, we find a higher incidence of heavily-obscured quasars in disturbed/merging galaxies compared to the unobscured ones, thus possibly representing an earlier stage of evolution, after which the system is relaxing and becoming unobscured.
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