Molecular gas content in typical L* galaxies at z ∼ 1.5 − 3

To extend the molecular gas measurements to typical L* star-forming galaxies (SFGs) at z ∼ 1.5 − 3, we have observed CO emission for five strongly-lensed galaxies selected from the Herschel Lensing Survey. The combined sample of our L* SFGs with CO-detected SFGs at z >1 from the literature shows a large spread in star formation efficiency (SFE). We find that this spread in SFE is due to variations of several physical parameters, primarily the specific star formation rate, but also stellar mass and redshift. An increase of the molecular gas fraction (f gas) is observed from z ∼ 0.2 to z ∼ 1.2, followed by a quasi non-evolution toward higher redshifts, as found in earlier studies. We provide the first measure of f gas of z >1 SFGs at the low-stellar mass end between 109.4 < M∗/M⊙ < 109.9, which shows a clear f gas uptur

SHARDS frontier fields: physical properties of a low-mass Lyα emitter at z = 5.75

We analyze the properties of a multiply-imaged Lyman-alpha (Lya) emitter at z=5.75 identified through SHARDS Frontier Fields intermediate-band imaging of the Hubble Frontier Fields (HFF) cluster Abell 370. The source, A370-L57, has low intrinsic luminosity (M_UV~-16.5), steep UV spectral index (\beta=-2.4+/-0.1), and extreme rest-frame equivalent width of Lya (EW(Lya)=420+180-120 \AA). Two different gravitational lens models predict high magnification (\mu~10--16) for the two detected counter-images, separated by 7", while a predicted third counter-image (\mu~3--4) is undetected. We find differences of ~50% in magnification between the two lens models, quantifying our current systematic uncertainties. Integral field spectroscopy of A370-L57 with MUSE shows a narrow (FWHM=204+/-10 km/s) and asymmetric Lya profile with an integrated luminosity L(Lya)~10^42 erg/s. The morphology in the HST bands comprises a compact clump (r_e<100 pc) that dominates the Lya and continuum emission and several fainter clumps at projected distances <1 kpc that coincide with an extension of the Lya emission in the SHARDS F823W17 and MUSE observations. The latter could be part of the same galaxy or an interacting companion. We find no evidence of contribution from AGN to the Lya emission. Fitting of the spectral energy distribution with stellar population models favors a very young (t<10 Myr), low mass (M*~10^6.5 Msun), and metal poor (Z<4x10^-3) stellar population. Its modest star formation rate (SFR~1.0 Msun/yr) implies high specific SFR (sSFR~2.5x10^-7 yr^-1) and SFR density (Sigma_SFR ~ 7-35 Msun/yr/kpc^2). The properties of A370-L57 make it a good representative of the population of galaxies responsible for cosmic reionization.Comment: 14 pages, 8 figures, 4 tables. Accepted for publication in Ap

Properties and star formation histories of high-z IR-detected galaxies with Herschel

The Herschel Space Observatory (ESA) has offered an unprecedented view of the far infrared (FIR) emission of the Universe, granting astronomers access over more than 10 billion years of galaxy evolution. Star formation and the closely related dust creation are two central aspects that led the Universe to its present state of diversity and chemical enrichment. They also set the rules for observing the Universe and Herschel has been crucial to complete our coverage of the electromagnetic spectrum. Using a wealth of ancillary observational data along the FIR, this thesis focuses on the multi-wavelength characterization of IR-detected star-forming galaxies of intermediate to high redshift (1 to 4) in the aftermath of the Herschel mission. It is composed of three main stages, the central purpose of which is to derive the physical properties and constrain the star formation histories (SFHs) of the studied galaxies, via the analysis of their spectral energy distribution

Hospitals’ Energy Efficiency in the Perspective of Saving Resources and Providing Quality Services through Technological Options: A Systematic Literature Review

The effects of climate change, in combination with the recent energy crisis, have brought the energy efficiency issues of hospitals markedly to the fore. Hospitals are considered among the most energy-intensive buildings, which is why they have become a top priority for governments wishing to upgrade their energy efficiency. Given the critical nature of the work of hospitals and the model of healthcare provision (nursing cover 24 h per day, 7 days a week) it is very hard to achieve energy cuts. The international literature shows that the energy efficiency of hospitals is a complex process that requires further research. This need is covered by the present systematic literature review, which captures the existing knowledge on energy monitoring strategies, assessment, and upgrading through technology, resources-saving strategies, and the relationship between energy efficiency and the quality of the service provision, while also identifying future research considerations and the potential for supporting researchers’ work. Additionally, this study adds aggregated data to the literature, as far as the energy performance of buildings is concerned, and allows investors to have data exported from energy surveys at their disposal. At the same time, it suggests the further exploration of alternative energy technologies, based on all renewable energy sources rather than only solar power systems. This highlights the need for a comparative examination of hospitals with different climatic and socio-economic environments, to better determine what technologies effectively serve the energy needs of each region. Finally, this survey considers it necessary to connect the energy efficiency of hospital units with the awareness of the management and workforce in the saving of energy resources. Due to the fact that most studies are oriented toward the energy performance of very large-sized hospitals, it is suggested that in the future, the research lens should also be focused on the smaller private and public sectors’ health units

Molecular gas content in typical L* galaxies at z ∼ 1.5 − 3

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