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- Ackley, K., et al.
(författare)
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Observational constraints on the optical and near-infrared emission from the neutron star-black hole binary merger candidate S190814bv
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 643
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Tidskriftsartikel (refereegranskat)abstract
- Context. Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS.Aims. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger.Methods. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency - a 50% (90%) credible area of 5 deg(2) (23 deg(2)) - despite the relatively large distance of 26752 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups.Results. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS-BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r similar to 22 (resp. K similar to 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total similar to 50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M greater than or similar to 0.1 M-circle dot to a high (> 90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger.Conclusions. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxy-targeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event.
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| 2. |
- Saharil, Farizah, et al.
(författare)
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LOW-TEMPERATURE CMOS-COMPATIBLE 3D-INTEGRATION OF MONOCRYSTALLINE-SILICON BASED PZT RF MEMS SWITCH ACTUATORS ON RF SUBSTRATES
- 2010
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Ingår i: MEMS 2010. - New York : Ieee. - 9781424457649 ; , s. 47-50
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Konferensbidrag (refereegranskat)abstract
- This paper presents a low temperature (200 degrees C) CMOS-compatible fabrication process for integrating high-temperature deposited lead zirconate titanate (PZT) on this film monocrystalline-silicon piezoelectric actuators, onto an RF substrate, and successful demonstration of this process for fabrication of metal-contact RF-MEMS switches. The patterned PZT/silicon multi-layer stack is transfer-bonded from a silicon-on-insulator (SOI) donor wafter to AF-45 glass RF substrate using adhesive wafer transfer bonding. Furthermore, several strategies have been investigate to drastically reduce the post bonding misalignment created by the shear forces between the bonding chucks during wafer bonding.
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| 5. |
- Silaev, Mihail, et al.
(författare)
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Long-Range Spin Accumulation from Heat Injection in Mesoscopic Superconductors with Zeeman Splitting
- 2015
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 114:16
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Tidskriftsartikel (refereegranskat)abstract
- We describe far-from-equilibrium nonlocal transport in a diffusive superconducting wire with a Zeeman splitting, taking into account different spin relaxation mechanisms. We demonstrate that due to the Zeeman splitting, an injection of current in a superconducting wire creates spin accumulation that can only relax via thermalization. This effect leads to a long-range spin accumulation detectable in the nonlocal signal. Our model gives a qualitative explanation and provides accurate fits of recent experimental results in terms of realistic parameters.
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| 6. |
- Silaev, Mihail, et al.
(författare)
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Spin Hanle effect in mesoscopic superconductors
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 91:2, s. 024506-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of spin transport in a superconducting mesoscopic spin valve under the action of a magnetic field misaligned with respect to the injected spin. We demonstrate that superconductivity can either strongly enhance or suppress the coherent spin rotation, depending on the type of spin relaxation mechanism being dominated either by spin-orbit coupling or spin-flip scattering at impurities. We also predict a subgap contribution to the nonlocal conductance in multiterminal superconducting hybrid structures which completely eliminates the effect of spin rotation at sufficiently low temperatures.
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