1. Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic CloudA. Acharyya, Saptashwa BHATTACHARYYA, Samo Stanič, Veronika VODEB, Serguei Vorobiov, Gabrijela ZAHARIJAS, Danilo Zavrtanik, Marko Zavrtanik, Miha ŽIVEC, 2023, izvirni znanstveni članek Opis: A deep survey of the Large Magellanic Cloud at ∼ 0.1−100 TeV photon energies with the Cherenkov Telescope Array is planned.
We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters,
mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N 157B, N 132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered
objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3−2.4 pending a flux increase by a factor > 3−4 over ∼ 2015−2035. Large-scale interstellar emission remains mostly out of reach of the survey if its > 10 GeV spectrum has a soft photon index ∼ 2.7, but degree-scale 0.1 − 10 TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100 GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1 − 10% of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within < 100 pc. Finally, the survey could probe the canonical velocity-averaged cross section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles. Ključne besede: very-high energy (VHE) gamma-rays, Cherenkov Telescope Array (CTA) Observatory, Large Magellanic Cloud, pulsar wind nebulas, star-forming regions, cosmic rays, dark matter Objavljeno v RUNG: 02.06.2023; Ogledov: 376; Prenosov: 0 Gradivo ima več datotek! Več... |
2. The impact of cloudiness and cloud type on the atmospheric heating rate of black and brown carbon in the Po ValleyLuca Ferrero, Asta Gregorič, Griša Močnik, Martin Rigler, Sergio Cogliati, Francesca Barnaba, Luca Di Liberto, Gian Paolo Gobbi, Niccolò Losi, Ezio Bolzacchini, 2021, izvirni znanstveni članek Opis: We experimentally quantified the impact of cloud fraction and cloud type on the heating rate (HR) of black and brown carbon (HRBC and HRBrC). In particular, we examined in more detail the cloud effect on the HR detected in a previous study (Ferrero et al., 2018). High-time-resolution measurements of the aerosol absorption coefficient at multiple wavelengths were coupled with spectral measurements of the direct, diffuse and surface reflected irradiance and with lidar–ceilometer data during a field campaign in Milan, Po Valley (Italy). The experimental set-up allowed for a direct determination of the total HR (and its speciation: HRBC and HRBrC) in all-sky conditions (from clear-sky conditions to cloudy). The highest total HR values were found in the middle of winter (1.43 ± 0.05 K d−1), and the lowest were in spring (0.54 ± 0.02 K d−1). Overall, the HRBrC accounted for 13.7 ± 0.2 % of the total HR, with the BrC being characterized by an absorption Ångström exponent (AAE) of 3.49 ± 0.01. To investigate the role of clouds, sky conditions were classified in terms of cloudiness (fraction of the sky covered by clouds: oktas) and cloud type (stratus, St; cumulus, Cu; stratocumulus, Sc; altostratus, As; altocumulus, Ac; cirrus, Ci; and cirrocumulus–cirrostratus, Cc–Cs). During the campaign, clear-sky conditions were present 23 % of the time, with the remaining time (77 %) being characterized by cloudy conditions. The average cloudiness was 3.58 ± 0.04 oktas (highest in February at 4.56 ± 0.07 oktas and lowest in November at 2.91 ± 0.06 oktas). St clouds were mostly responsible for overcast conditions (7–8 oktas, frequency of 87 % and 96 %); Sc clouds dominated the intermediate cloudiness conditions (5–6 oktas, frequency of 47 % and 66 %); and the transition from Cc–Cs to Sc determined moderate cloudiness (3–4 oktas); finally, low cloudiness (1–2 oktas) was mostly dominated by Ci and Cu (frequency of 59 % and 40 %, respectively).
HR measurements showed a constant decrease with increasing cloudiness of the atmosphere, enabling us to quantify for the first time the bias (in %) of the aerosol HR introduced by the simplified assumption of clear-sky conditions in radiative-transfer model calculations. Our results showed that the HR of light-absorbing aerosol was ∼ 20 %–30 % lower in low cloudiness (1–2 oktas) and up to 80 % lower in completely overcast conditions (i.e. 7–8 oktas) compared to clear-sky ones. This means that, in the simplified assumption of clear-sky conditions, the HR of light-absorbing aerosol can be largely overestimated (by 50 % in low cloudiness, 1–2 oktas, and up to 500 % in completely overcast conditions, 7–8 oktas).
The impact of different cloud types on the HR was also investigated. Cirrus clouds were found to have a modest impact, decreasing the HRBC and HRBrC by −5 % at most. Cumulus clouds decreased the HRBC and HRBrC by −31 ± 12 % and −26 ± 7 %, respectively; cirrocumulus–cirrostratus clouds decreased the HRBC and HRBrC by −60 ± 8 % and −54 ± 4 %, which was comparable to the impact of altocumulus (−60 ± 6 % and −46 ± 4 %). A higher impact on the HRBC and HRBrC suppression was found for stratocumulus (−63 ± 6 % and −58 ± 4 %, respectively) and altostratus (−78 ± 5 % and −73 ± 4 %, respectively). The highest impact was associated with stratus, suppressing the HRBC and HRBrC by −85 ± 5 % and −83 ± 3 %, respectively. The presence of clouds caused a decrease of both the HRBC and HRBrC (normalized to the absorption coefficient of the respective species) of −11.8 ± 1.2 % and −12.6 ± 1.4 % per okta. This study highlights the need to take into account the role of both cloudiness and different cloud types when estimating the HR caused by both BC and BrC and in turn decrease the uncertainties associated with the quantification of their impact on the climate. Ključne besede: black carbon, brown carbon, cloud, atmospheric heating rate, climate change Objavljeno v RUNG: 29.03.2021; Ogledov: 1847; Prenosov: 0 Gradivo ima več datotek! Več... |
3. Impact of bacterial ice nucleating particles on weather predicted by a numerical weather prediction modelMaher Sahyoun, Ulrik S. Korsholm, Jens H. Sørensen, Tina Šantl Temkiv, Kai Finster, Ulrich Gosewinkel, Niels Woetmann Nielsen, 2017, izvirni znanstveni članek Ključne besede: Heterogeneous ice nucleation, Bacterial INP, Cloud ice, Precipitation, Global solar radiation, Numerical weather prediction model Objavljeno v RUNG: 04.01.2021; Ogledov: 2384; Prenosov: 0 Gradivo ima več datotek! Več... |
4. The microbial diversity of a storm cloud as assessed by hailstonesTina Šantl Temkiv, Kai Finster, Bjarne Munk Hansen, Niels Woetmann Nilesen, Ulrich Gosewinkel Karlson, 2012, izvirni znanstveni članek Ključne besede: cloud-borne bacteria, bacterial diversity, species richness, species evenness, atmospheric chemistry, biogeography Objavljeno v RUNG: 04.01.2021; Ogledov: 1947; Prenosov: 0 Gradivo ima več datotek! Več... |
5. Hailstones: A Window into the Microbial and Chemical Inventory of a Storm CloudTina Šantl Temkiv, Kai Finster, Thorsten Dittman, Bjarne Munk Hansen, Runar Thyrhaug, Niels Woetmann Nielsen, Ulrich Gosewinkel, 2013, izvirni znanstveni članek Ključne besede: atmospheric bacteria, atmospheric DOM, cloud microbiota, microbial activity Objavljeno v RUNG: 04.01.2021; Ogledov: 2029; Prenosov: 60
Celotno besedilo (402,78 KB) |
6. Highly Sensitive Determination of Pyoverdine in Cloud Water by HPLC-Thermal Lens SpectrometryLeja Goljat, Mitja Martelanc, Virginie Vinatier, Anne-Marie Delort, Mladen Franko, 2016, objavljeni povzetek znanstvenega prispevka na konferenci Opis: New method for pyoverdine and Fe(III)-pyoverdine detection was developed. Two isomers of pyoverdine and two isomers of Fe(III)-pyoverdine were separated isocraticaly on reversed-phase (RP)-C18 chromatograhic column and detected by DAD, FLD and TLS. HPLC-TLS method enables separation and determination of pyoverdine and Fe(III)-pyoverdine in a single run and excels in superior sensitivities when compared to conventional HPLC-DAD system. Ključne besede: Pyoverdine, Fe(III)-pyoverdine, cloud water, high-performance liquid chromatography, thermal lens spectrometry Objavljeno v RUNG: 04.07.2016; Ogledov: 5017; Prenosov: 0 |