ABSTRACT In this catalog, we present the results of a systematic study of 295 short gamma-ray bursts (GRBs) detected by Konus-Wind (KW) from 1994 to 2010. From the temporal and spectral analyses of ...the sample, we provide the burst durations, the spectral lags, the results of spectral fits with three model functions, the total energy fluences, and the peak energy fluxes of the bursts. We discuss evidence found for an additional power-law spectral component and the presence of extended emission in a fraction of the KW short GRBs. Finally, we consider the results obtained in the context of the Type I (merger-origin)/Type II (collapsar-origin) classifications.
The in-orbit results and lessons learned of the first Finnish satellite Aalto-1 are briefly presented in this paper. Aalto-1, a three-unit CubeSat which was launched in June 2017, performed Aalto ...Spectral Imager (AaSI), Radiation Monitor (RADMON) and Electrostatic Plasma Brake (EPB) missions. The satellite partly fulfilled its mission objectives and allowed to either perform or attempt the experiments. Although attitude control was partially functional, AaSI and RADMON were able to acquire valuable measurements. EPB was successfully commissioned but the tether deployment was not successful.
In this paper, we present the intended mission, in-orbit experience in operating and troubleshooting the satellite, an overview of experiment results, as well as lessons learned that will be used in future missions.
•The launch and operations of first Finnish satellite, Aalto 1.•In orbit results and lessons learned of first miniaturized hyperspectral imager onboard a CubeSat.•In orbit results and lessons learned of miniaturized low power radiation monitor.•In orbit results and lessons learned of electrostatic plasma brake.•In orbit results and lessons learned of CubeSat platform.
In this catalog, we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected in the triggered mode of the Konus-Wind (KW) experiment during the ...period from 1997 February to 2016 June. The sample consists of 150 GRBs (including 12 short/hard bursts) and represents the largest set of cosmological GRBs studied to date over a broad energy band. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with two model functions, the total energy fluences, and the peak energy fluxes. Based on the GRB redshifts, which span the range , we estimate the rest-frame, isotropic-equivalent energy, and peak luminosity. For 32 GRBs with reasonably constrained jet breaks, we provide the collimation-corrected values of the energetics. We consider the behavior of the rest-frame GRB parameters in the hardness-duration and hardness-intensity planes, and confirm the "Amati" and "Yonetoku" relations for Type II GRBs. The correction for the jet collimation does not improve these correlations for the KW sample. We discuss the influence of instrumental selection effects on the GRB parameter distributions and estimate the KW GRB detection horizon, which extends to , stressing the importance of GRBs as probes of the early universe. Accounting for the instrumental bias, we estimate the KW GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which are in general agreement with those obtained in previous studies.
The design, integration, testing and launch of the first Finnish satellite Aalto-1 is briefly presented in this paper. Aalto-1, a three-unit CubeSat, launched into Sun-synchronous polar orbit at an ...altitude of approximately 500 km, is operational since June 2017. It carries three experimental payloads: Aalto Spectral Imager(AaSI), Radiation Monitor (RADMON) and Electrostatic Plasma Brake (EPB). AaSI is a hyperspectral imager in visible and near-infrared (NIR) wavelength bands, RADMON is an energetic particle detector and EPB is a de-orbiting technology demonstration payload. The platform was designed to accommodate multiple payloads while ensuring sufficient data, power, radio, mechanical and electrical interfaces. The design strategy of platform and payload subsystems consists of in-house development and commercial subsystems. The CubeSat Assembly, Integration & Test (AIT) followed Flatsat-Engineering-Qualication Model (EQM)-Flight Model (FM) model philosophy for qualification and acceptance.
The paper briefly describes the design approach of platform and payload subsystems, their integration and test campaigns and spacecraft launch. The paper also describes the ground segment & services that were developed by Aalto-1 team.
•The design and development of multi-payload CubeSat, Aalto 1.•The miniaturized hyperspectral imager based on piezo-actuated tunable FPI.•The de-orbiting payload consisting of coulomb drag force.•The miniaturized low power radiation monitor.•The platform design approach consisting of inhouse development and commercial subsystems.
THE ULTRALUMINOUS GRB 110918A Frederiks, D. D.; Hurley, K.; Svinkin, D. S. ...
The Astrophysical journal,
12/2013, Letnik:
779, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We report on the final Interplanetary Network localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a ...typical duration, a moderate peak energy of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z = 0.984, a huge isotropic-equivalent energy release E sub(iso) = (2.1 + or - 0.1) x 10 super(54) erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity L sub(iso) = (4.7 + or - 0.2) x 10 super(54) erg s super(-1). A tail of the soft gamma -ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. The Swift/X-Ray Telescope and the Swift/Ultraviolet Optical Telescope observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break.
Oxygen-deficient zones (ODZs) are major sites of net natural
nitrous oxide (N2O) production and emissions. In order to understand
changes in the magnitude of N2O production in response to global
...change, knowledge on the individual contributions of the major microbial
pathways (nitrification and denitrification) to N2O production and
their regulation is needed. In the ODZ in the coastal area off Peru, the
sensitivity of N2O production to oxygen and organic matter was
investigated using 15N tracer experiments in combination with quantitative PCR (qPCR) and
microarray analysis of total and active functional genes targeting archaeal amoA
and nirS as marker genes for nitrification and denitrification, respectively.
Denitrification was responsible for the highest N2O production with a
mean of 8.7 nmol L−1 d−1 but up to 118±27.8 nmol L−1 d−1 just below the oxic–anoxic interface. The highest N2O production
from ammonium oxidation (AO) of 0.16±0.003 nmol L−1 d−1
occurred in the upper oxycline at O2 concentrations of 10–30 µmol L−1 which coincided with the highest archaeal amoA transcripts/genes.
Hybrid N2O formation (i.e., N2O with one N atom from NH4+
and the other from other substrates such as NO2-) was the dominant
species, comprising 70 %–85 % of total produced N2O from
NH4+, regardless of the ammonium oxidation rate or O2
concentrations. Oxygen responses of N2O production varied with
substrate, but production and yields were generally highest below 10 µmol L−1 O2. Particulate organic matter additions increased
N2O production by denitrification up to 5-fold, suggesting increased
N2O production during times of high particulate organic matter export.
High N2O yields of 2.1 % from AO were measured, but the overall
contribution by AO to N2O production was still an order of magnitude
lower than that of denitrification. Hence, these findings show that
denitrification is the most important N2O production process in low-oxygen conditions fueled by organic carbon supply, which implies a positive
feedback of the total oceanic N2O sources in response to increasing
oceanic deoxygenation.
Abstract
The article presents the results of the study of the effect of direct laser growth modes on the shaping of single rollers and walls made of heat-resistant alloy. Powder from heat-resistant ...nickel alloy of the HN50VMTUB brand, manufactured by JSC “Kompozit” and JSC “Opytnyj zavod “Mikron”, was used as the material under study. The morphology of the deposited material is considered. The study of microhardness is carried out.
In the past few years the phenomenon of spin-dependent tunneling (SDT) in magnetic tunnel junctions (MTJs) has aroused enormous interest and has developed into a vigorous field of research. The large ...tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible application in random access memories and magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of SDT. One such question is the role of interfaces in MTJs and their effect on the spin polarization of the tunneling current and TMR. In this paper we consider different models which suggest that the spin polarization is primarily determined by the electronic and atomic structure of the ferromagnet/insulator interfaces rather than by their bulk properties. First, we consider a simple tight-binding model which demonstrates that the existence of interface states and their contribution to the tunneling current depend on the degree of hybridization between the orbitals on metal and insulator atoms. The decisive role of the interfaces is further supported by studies of spin-dependent tunneling within realistic first-principles models of Co/vacuum/Al, Co/Al
2O
3/Co, Fe/MgO/Fe, and Co/SrTiO
3/Co MTJs. We find that variations in the atomic potentials and bonding strength near the interfaces have a profound effect resulting in the formation of interface resonant states, which dramatically affect the spin polarization and TMR. The strong sensitivity of the tunneling spin polarization and TMR to the interface atomic and electronic structure dramatically expands the possibilities for engineering optimal MTJ properties for device applications.
The Solar Intensity X-ray and particle Spectrometer (SIXS) on the BepiColombo Mercury Planetary Orbiter (“Bepi”) measures the direct solar X-rays, energetic protons, and electrons that bombard, and ...interact with, the Hermean surface. The interactions result in X-ray fluorescence and scattering, and particle induced X-ray emission (PIXE), i.e. “glow” of the surface in X-rays. Simultaneous monitoring of the incident and emitted radiation enables derivation of the abundances of some chemical elements and scattering properties of the outermost surface layer of the planet, and it may reveal other sources of X-ray emission, due to, for example, weak aurora-like phenomena in Mercury’s exosphere. Mapping of the Hermean X-ray emission is the main task of the MIXS instrument onboard BepiColombo. SIXS data will also be used for investigations of the solar X-ray corona and solar energetic particles (SEP), both in the cruise phase and the passes of the Earth, Venus and Mercury before the arrival at Mercury’s orbit, and the final science phase at Mercury’s orbit. These observations provide the first-ever opportunity for in-situ measurements of the propagation of SEPs, their interactions with the interplanetary magnetic field, and space weather phenomena in multiple locations throughout the inner solar system far away from the Earth, and more extensively at Mercury’s orbit.
In this paper we describe the scientific objectives, design and calibrations, operational principles, and scientific performance of the final SIXS instrument launched to the mission to planet Mercury onboard BepiColombo. We also provide the first analysis results of science observations with SIXS, that were made during the Near-Earth Commissioning Phase and early cruise phase operations in 2018–19, including the background X-ray sky observations and “first light” observations of the Sun with the SIXS X-ray detection system (SIXS-X), and in-situ energetic electron and proton observations with the SIXS Particle detection system (SIXS-P).
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