TY  - GEN
A1  - Abdalla, Hassan E.
A1  - Adam, Remi
A1  - Aharonian, Felix A.
A1  - Benkhali, Faical Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, Masanori
A1  - Arcaro, C
A1  - Armand, Catherine
A1  - Armstrong, T.
A1  - Egberts, Kathrin
T1  - Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1202 
KW  - BL Lacertae objects: individual
KW  - galaxies: high-redshift
KW  - gamma-rays: general
KW  - Resolved and unresolved sources as a function of wavelength
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-526000
SN  - 1866-8372
IS  - 4
ER  - 
TY  - JOUR
A1  - Crovetto, Andrea
A1  - Hempel, Hannes
A1  - Rusu, Marin
A1  - Choubrac, Leo
A1  - Kojda, Sandrino Danny
A1  - Habicht, Klaus
A1  - Unold, Thomas
T1  - Water adsorption enhances electrical conductivity in transparent p-type CuI
JF  - ACS applied materials & interfaces
N2  - CuI has been recently rediscovered as a p-type transparent conductor with a high figure of merit. Even though many metal iodides are hygroscopic, the effect of moisture on the electrical properties of CuI has not been clarified. In this work, we observe a 2-fold increase in the conductivity of CuI after exposure to ambient humidity for 5 h, followed by slight long-term degradation. Simultaneously, the work function of CuI decreases by almost 1 eV, which can explain the large spread in the previously reported work function values. The conductivity increase is partially reversible and is maximized at intermediate humidity levels. On the basis of the large intragrain mobility measured by THz spectroscopy, we suggest that hydration of grain boundaries may be beneficial for the overall hole mobility.
KW  - transparent conductors
KW  - CuI
KW  - copper iodide
KW  - conductivity
KW  - humidity
KW  - p-type
KW  - work function
Y1  - 2020
U6  - https://doi.org/10.1021/acsami.0c11040
SN  - 1944-8244
SN  - 1944-8252
VL  - 12
IS  - 43
SP  - 48741
EP  - 48747
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Meyer, Dominique M.-A.
A1  - Petrov, Mykola
A1  - Pohl, Martin
T1  - Wind nebulae and supernova remnants of very massive stars
JF  - Monthly notices of the Royal Astronomical Society
N2  - A very small fraction of (runaway) massive stars have masses exceeding 60-70 M-circle dot and are predicted to evolve as luminous blue variable and Wolf-Rayet stars before ending their lives as core-collapse supernovae. Our 2D axisymmetric hydrodynamical simulations explore how a fast wind (2000 km s(-1)) and high mass-loss rate (10(-5)M(circle dot) yr(-1)) can impact the morphology of the circumstellar medium. It is shaped as 100 pc-scale wind nebula that can be pierced by the driving star when it supersonically moves with velocity 20-40 km s(-1) through the interstellar medium (ISM) in the Galactic plane. The motion of such runaway stars displaces the position of the supernova explosion out of their bow shock nebula, imposing asymmetries to the eventual shock wave expansion and engendering Cygnus-loop-like supernova remnants. We conclude that the size (up to more than 200 pc) of the filamentary wind cavity in which the chemically enriched supernova ejecta expand, mixing efficiently the wind and ISM materials by at least 10 per cent in number density, can be used as a tracer of the runaway nature of the very massive progenitors of such 0.1Myr old remnants. Our results motivate further observational campaigns devoted to the bow shock of the very massive stars BD+43 degrees 3654 and to the close surroundings of the synchrotron-emitting Wolf-Rayet shell G2.4+1.4.
KW  - shock waves
KW  - methods: numerical
KW  - circumstellar matter
KW  - stars: massive
Y1  - 2020
U6  - https://doi.org/10.1093/mnras/staa554
SN  - 0035-8711
SN  - 1365-2966
VL  - 493
IS  - 3
SP  - 3548
EP  - 3564
PB  - Oxford Univ. Press
CY  - Oxford
ER  -