| 1. |
- Erni, W., et al.
(author)
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Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker
- 2013
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In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 49:2
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Journal article (peer-reviewed)abstract
- This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described.
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| 2. |
- Smirnov, A. V., et al.
(author)
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The Current Stage of Development of the Receiving Complex of the Millimetron Space Observatory
- 2012
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In: Radiophysics and Quantum Electronics (English Translation of Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika). - : Springer Science and Business Media LLC. - 0033-8443 .- 1573-9120. ; 54:8-9, s. 557-568
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Journal article (peer-reviewed)abstract
- We present an overview of the state of the onboard receiving complex of the Millimetron space observatory in the development phase of its preliminary design. The basic parameters of the onboard equipment planned to create and required for astrophysical observations are considered. A review of coherent and incoherent detectors, which are central to each receiver of the observatory, is given. Their characteristics and limiting parameters feasible at the present level of technology are reported.
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| 3. |
- Perucho, M., et al.
(author)
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S5 0836+710: An FRII jet disrupted by the growth of a helical instability?
- 2012
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 545, s. A65-
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Journal article (peer-reviewed)abstract
- The remarkable stability of extragalactic jets is surprising, given the reasonable possibility of the growth of instabilities. In addition, much work in the literature has invoked this possibility in order to explain observed jet structures and obtain information from these structures. For example, it was recently shown that the observed helical structures in the jet in S5 0836+710 could be associated with helical pressure waves generated by Kelvin-Helmholtz instability.Our aim is to resolve the arc-second structure of the jet in the quasar S5 0836+710 and confirm the lack of a hot-spot (reverse jet-shock) found by present observing arrays, as this lack implies a loss of jet collimation before interaction with the intergalactic medium.In this work, we use an observation performed in 2008 using EVN and MERLIN. The combined data reduction has provided a complete image of the object at arc-second scales.The lack of a hot-spot in the arc-second radio structure istaken as evidence that the jet losses its collimation between the VLBI region and the region of interaction with the ambient medium. This result, together with the previous identification of the helical structures in the jet with helical pressure waves that grow in amplitude with distance, allow us to conclude that the jet is probably disrupted by the growth of Kelvin-Helmholtz instability. This observational evidence confirms that the physical parameters of jets can be extracted using the assumption that instability is present in jets and can be the reason for many observed structures. Interestingly, the observed jet is classified as a FRII object in terms of its luminosity, but its large-scale morphology does not correspond to this classification. The implications of this fact are discussed.
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| 4. |
- Marti-Vidal, Ivan, 1980, et al.
(author)
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Over-resolution of compact sources in interferometric observations
- 2012
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 541, s. A135-
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Research review (peer-reviewed)abstract
- We review the effects of source size in interferometric observations and focus on the cases of very compact sources.If a source is extremely compact and/or weak (so it is not possible to detect signature of source structure in the visibilities) we describe a test of hypothesis that can be used to set a strong upper limit to the size of the source. We also estimate the minimum possible size of a source whose structure can still be detected by an interferometer (i.e., the maximum theoretical over-resolution power of an interferometer), which depends on the overall observing time, the compactness in the array distribution, and the sensitivity of the receivers. As a result, and depending on the observing frequency, the over-resolution power of forthcoming ultra-sensitive arrays, like the Square Kilometer Array (SKA), may allow us to study details of sources at angular scales down to a few micro-arcsec.
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| 5. |
- Mezcua, M., et al.
(author)
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The resolved structure of the extragalactic supernova remnant SNR 4449-1
- 2013
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 436:3, s. 2454-2460
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Journal article (peer-reviewed)abstract
- We present very long baseline interferometry (VLBI) observations of the milliarcsecondscale radio structure of the supernova remnant SNR 4449-1 in the galaxy NGC 4449. This young and superluminous remnant was observed at 1.6 GHz (λ = 18 cm) with the European VLBI Network. The observations confirm earlier identifications of this object with a supernova remnant (SNR) while revealing a somewhat different morphology compared with the structure reported by Bietenholz et al. from VLBI observations at 1.4 GHz. This difference is discussed here in the context of structural sensitivity of both observations. The 1.6 GHz image yields accurate estimates of the size (0.0422 arcsec × 0.0285 arcsec and 0.8 pc × 0.5 pc) and age (~55 yr) of SNR 4449-1. With a total flux of 6.1 ± 0.6 mJy measured in the VLBI image, the historical light curve of the source can be well represented by a power-law decay with a power index of -1.19 ± 0.07. The SNR exhibits a decline rate of the radio emission of 2.2 ± 0.1 per cent yr-1 and a radio luminosity of 1.74 × 1035 erg s-1. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
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