3 research outputs found

    VALES VI: ISM enrichment in star-forming galaxies up to z∼\sim0.2 using 12^{12}CO(1-0), 13^{13}CO(1-0) and C18^{18}O(1-0) line luminosity ratios

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    We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations towards 27 low-redshift (0.02<z<0.20.02< z<0.2) star-forming galaxies taken from the Valpara\'iso ALMA/APEX Line Emission Survey (VALES). We perform stacking analyses of the 12^{12}CO(1−01-0), 13^{13}CO(1−01-0) and C18^{18}O(1−01-0) emission lines to explore the L′L' (12^{12}CO(1−01-0))/L′L'(13^{13}CO(1−01-0))) (hereafter L′L'(12^{12}CO)/L′L'(13^{13}CO)) and L′L'(13^{13}CO(1−01-0))/L′L'(C18^{18}O(1−01-0)) (hereafter L′L'(13^{13}CO)/L′L'(C18^{18}O) line luminosity ratio dependence as a function of different global galaxy parameters related to the star formation activity. The sample has far-IR luminosities 1010.1−11.910^{10.1-11.9}L⊙_{\odot} and stellar masses of 109.8−10.910^{9.8-10.9}M⊙_{\odot} corresponding to typical star-forming and starburst galaxies at these redshifts. On average we find a L′L'(12^{12}CO)/L′L'(13^{13}CO) line luminosity ratio value of 16.1±\pm2.5. Galaxies with evidences of possible merging activity tend to show higher L′L'(12^{12}CO)/L′L'(13^{13}CO) ratios by a factor of two, while variations of this order are also found in galaxy samples with higher star formation rates or star formation efficiencies. We also find an average L′L'(13^{13}CO)/L′L'(C18^{18}O) line luminosity ratio of 2.5±\pm0.6, which is in good agreement with those previously reported for starburst galaxies. We find that galaxy samples with high LIRL_{\text{IR}}, SFR and SFE show low L′L'(13^{13}CO)/L′L'(C18^{18}O) line luminosity ratios with high L′L'(12^{12}CO)/L′L'(13^{13}CO) line luminosity ratios, suggesting that these trends are produced by selective enrichment of massive stars in young starbursts.Comment: 16 pages, 10 figures to be published in MNRA

    An innovative silicon photomultiplier digitizing camera for gamma-ray astronomy

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    The single-mirror small-size telescope (SST-1M) is one of the three proposed designs for the small-size telescopes (SSTs) of the Cherenkov Telescope Array (CTA) project. The SST-1M will be equipped with a 4 m-diameter segmented reflector dish and an innovative fully digital camera based on silicon photo-multipliers. Since the SST sub-array will consist of up to 70 telescopes, the challenge is not only to build telescopes with excellent performance, but also to design them so that their components can be commissioned, assembled and tested by industry. In this paper we review the basic steps that led to the design concepts for the SST-1M camera and the ongoing realization of the first prototype, with focus on the innovative solutions adopted for the photodetector plane and the readout and trigger parts of the camera. In addition, we report on results of laboratory measurements on real scale elements that validate the camera design and show that it is capable of matching the CTA requirements of operating up to high moonlight background conditions
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