Probing the Soft X-ray Properties and Multi-Wavelength Variability of SN2023ixf and its Progenitor

We present a detailed analysis of nearly two decades of optical/UV and X-ray data to study the multi-wavelength pre-explosion properties and post-explosion X-ray properties of nearby SN2023ixf located in M101. We find no evidence of precursor activity in the optical to UV down to a luminosity of $\lesssim 7\times10^{4}\, \rm L_{\odot}$, while X-ray observations covering nearly 18 years prior to explosion show no evidence of luminous precursor X-ray emission down to an absorbed 0.3 - 10.0 keV X-ray luminosity of $\sim6\times10^{36}$ erg s$^{-1}$. Extensive Swift observations taken post-explosion did not detect soft X-ray emission from SN2023ixf within the first $\sim$3.3 days after first light, which suggests a mass-loss rate for the progenitor of $\lesssim5\times10^{-4}\,\rm M_{\odot}$ yr$^{-1}$ or a radius of $\lesssim4\times10^{15}$ cm for the circumstellar material. Our analysis also suggests that if the progenitor underwent a mass-loss episode, this had to occur $>$ 0.5 - 1.5 years prior to explosion, consistent with previous estimates. Swift detected soft X-rays from SN2023ixf $\sim4.25$ days after first light, and it rose to a peak luminosity of $\sim10^{39}$ erg s$^{-1}$ after 10 days and has maintained this luminosity for nearly 50 days post first light. This peak luminosity is lower than expected, given the evidence that SN2023ixf is interacting with dense material. However, this might be a natural consequence of an asymmetric circumstellar medium. X-ray spectra derived from merging all Swift observations over the first 50 days are best described by a two-component bremsstrahlung model consisting of a heavily absorbed and hotter component similar to that found using NuSTAR, and a less-absorbed, cooler component. We suggest that this soft component arises from cooling of the forward shock similar to that found in Type IIn SN2010jl.Comment: 27 pages, 13 figure

Analysis of three ventilation systems in an office: Mixing, displacement and confluent jet

Proyecto confidencial (Riunet)Panjkov Zafra-Polo, I. (2014). Analysis of three ventilation systems in an office: Mixing, displacement and confluent jet. http://hdl.handle.net/10251/39866.Archivo delegad

Analysis of three ventilation systems in an office: Mixing, displacement and confluent jet ventilation system. : Analysis of temperature gradient, tracer gas and thermal comfort.

Scandinavian countries have always been the first in investigation and development of new ventilation systems. In the last years, engineers from Finland and Sweden are studying a new ventilation system known “Confluent jet ventilation system” which is trying to improve displacement and mixing results. The aim of this thesis master is to study the behaviour of three different ventilation systems, mixing ventilation, displacement ventilation and confluent jet ventilation, in an office room by mean of three analysis, temperature gradient analysis, tracer gas analysis and thermal comfort analysis, and to compare them to know if the new one, confluent jet, increases the performance of mixing or displacement ventilation system. In case of confluent jet ventilation system, there were two different cases: one with the supply air device at 2.2m high, and the other with it at 1.7m high to compare which one was the correct position and gets the best results. For each studied system 3 different cases were analyzed, having the same parameters each one of them for the three ventilation systems.The measurements were taken in an office room located in the laboratory of the University of Gävle, Högskolan I Gävle, in collaboration with the Finnish company specialized in ventilation systems, Stravent. For temperature gradient analysis, ten sensors took temperatures from the low level, 0.1m high, to the top level of the room, 2.4m, during all the time that the other measurements were being taken. For tracer gas analysis, a data logger took measurements of the contaminant concentration, N2O, from when the contaminant was thrown into the room until it disappeared following a Decay curve. Lastly, in thermal comfort analysis 4 transducers took measurements each 12 minutes of air temperature, operative temperature, air velocity and air humidity are measured in 6 different points inside the office room and at 3 different heights, 0.1m, 1.1m and 1.7m. After analyzing the results of temperature gradient, tracer gas and thermal comfort the best results were obtained by confluent jet system with the supply air device at 2.2m in case of temperature gradient, since the difference of temperatures between the low and the top level were the minimum and contaminants and indoor air were not in a homogeneous mixing. In case of tracer gas, the results about air change efficiency were not the expected because they showed a well-mixed situation for every system and it should not have been like that. It was caused for the influence of a cooling system situated in the ceiling of the room and the temperature difference between inside and outside the room that affected more than expected. Finally, in thermal comfort analysis, the best results were obtained by confluent jet ventilation, therefore in case of the supply air device at 2.2m and in case of it at 1.7m. To sum up, taking account the results achieved, the confluent jet ventilation got the best results and showed that it is a new ventilation system that must be taken in consideration in the following buildings. Between supply air device at 2.2m and 1.7m the results were very similar, but a bit better in case of the highest height.

PRODUCTS OF THE PICKLING SOLUTIONS REGENERATION OF THE BELARUSIAN METALLURGICAL WORKS AS RAW MATERIALS FOR RECEIVING OF MAGNETITE (FE304)

Conditions and possible mechanism of formation of magnetite from hematite are defined by means of mechano-chemical influence, where the product of regeneration forming on JSC «BMZ» is used as initial raw materials

Time-dependent batch settling of flocculated suspensions

The equations governing the settling and consolidation of flocculated fully networked suspensions under the influence of gravity, based on the assumption that the network possesses a compressive yield stress P(oslash;) that is a function of local volume fraction (oslash;) only, are discussed. They are nonlinear partial differential equations with two moving boundaries, one at the top of the bed and the other marking the position of the consolidation region. A novel technique is used to solve these numerically. The time evolution of the volume fraction in the sedimenting column and the two moving boundaries are computed, and their dependence on the physical properties of the system are discussed. Analytic results for the steady state and the small time behavior are given

⁶⁰Fe deposition during the late Pleistocene and the Holocene echoes past supernova activity

Nuclides synthesized in massive stars are ejected into space viastellar winds and supernova explosions. The solar system (SS)moves through the interstellar medium and collects these nucle-osynthesis products. One such product is 60Fe, a radio nuclide witha half-life of 2.6 My that is predominantly produced in mas-sive stars and ejected in supernova explosions. Extraterres-trial60Fe has been found on Earth, suggesting close-by supernovaexplosions∼2to3and∼6Ma.Here,wereportonthedetectionof a continuous interstellar 60Fe influx on Earth over the past∼33,000 y. This time period coincides with passage of our SSthrough such interstellar clouds, which have a significantly largerparticle density compared to the local average interstellar me-dium embedding our SS for the past few million years. The inter-stellar 60Fe was extracted from five deep-sea sediment samplesand accelerator mass spectrometry was used for single-atomcounting. The low number of 19 detected atoms indicates a con-tinued but low influx of interstellar60Fe. The measured 60Fe time profile over the 33 ky, obtained with a time resolution of about±9 ky, does not seem to reflect any large changes in the inter-stellar particle density during Earth’s passage through local in-terstellar clouds, which could be expected if the local cloudrepresented an isolated remnant of the most recent supernovaejecta that traversed the Earth∼2 to 3 Ma. The identified 60 Fe influx may signal a late echo of some million-year-old supernovaewith the 60Fe-bearing dust particles still permeating the interstellar mediumWe thank the Antarctic Marine Geology ResearchFacility, Florida State University (C. Sjunneskog) for providing the sedimentcores. This work was funded by Austrian Science Fund project AI00428,through the European Science Foundation Collaborative Research ProjectCoDustMas; Australian Research Council projects DP140100136,DP180100495, and DP180100496; German Academic Exchange Service proj-ect 56266169; and The Group of Eight Australia–Germany Joint ResearchCooperation Scheme. J.F. acknowledges a stipend from the University ofVienna and R.G. support from the European Cooperation in Science andTechnology“ChETEC”Action (CA16117). We also acknowledge financialsupport from the Australian Government for the Heavy Ion Accelerator Fa-cility at ANU through the National Collaborative Research InfrastructureStrategy. ICP-MS measurements were performed by S. Beutner (HZDR