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Dissertations / Theses on the topic 'Astrofysica'
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Kerkwijk, Marten Henric van. "The mass of Vela X-1 the nature of Cygnus X-3 the character of Be stars." [S.l : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 1993. http://dare.uva.nl/document/92752.
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Sandin, Jan Fredrik. "Exotic phases of matter in compact stars /." Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1544/2007/05/.
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Retinò, Alessandro. "Magnetic reconnection in space plasmas : cluster spacecraft observations /." Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7891.
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Haugen, Nils Erlend Leinebø. "Energy spectra and scaling relations in numerical turbulence with laboratory and astrophysical applications." Doctoral thesis, Norwegian University of Science and Technology, Department of Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-890.
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<p>In this work we have focused on the statistical properties of turbulence.</p><p>This has been done in two different settings; one with neutral gas (the first four papers) and the other with ionized gas (the last four papers). Regarding the work on the neutral gas, we have looked at four different aspects;</p><p>1. Is the mean energy dissipation rate, C<sub>є</sub>, independent of Reynolds number for large Reynolds numbers? This is one of the fundamental questions in turbulence, and one believe the answer will be yes, but this is as yet not conclusive. In Paper 1 we demonstrate that the value of C<sub>є</sub><i> </i>is highly sensitive to the method used to measure it. This might explain the discrepancies in the values of C<sub>є</sub> found by previous authors. We also show how one can find C<sub>є</sub> for a spread of Reynolds numbers from a single simulation.</p><p>2. Is there a “bottleneck” in the energy spectrum between the inertial range and the dissipative range? Such a bottleneck is extremely weak - or totally absent, in wind tunnel experiments. In large numerical simulations however the bottleneck is pretty clear. In Paper 2 we show that this discrepancy is due to the physical nature of the one-dimensional energy spectra found in wind tunnels and the three dimensional energy spectra found in numerical simulations.</p><p>3. In order to achieve larger Reynolds numbers we investigate the possible errors introduced by using hyper viscosity instead of normal viscosity in Paper 3. Our conclusion is that while hyper viscosity increase the hight of the bottleneck and shortens the dissipative range, it does not otherwise have any significant effect on the energy spectrum, or the structure functions. The inertial range and the large scales are the same both with normal viscosity and hyper viscosity.</p><p>4. In decaying turbulence one can find relations under which the Navier- Stokes equations are scale invariant. Using these relations it has recently been suggested by Ditlevsen et al.[1] that the energy spectrum for decaying hydrodynamical turbulence can be described by a scaling function with only two arguments. This has previously been shown both analytically and experimentally, and in Paper 4 we also confirm this in numerical experiments.</p><p>For the ionized gas we have focused on five different aspects;</p><p>1. What does the large Reynolds number energy spectra look like? Are the kinetic and magnetic energy spectra similar? The results are as yet not conclusive because the Reynolds numbers are still too small, but it seems that what at first looked like a <i>k</i><sup>−3/2</sup> inertial range is actually the bottleneck in a <i>k</i><sup>−5/3 </sup>inertial range. Furthermore we have in Paper 5 found that the peak of the magnetic energy spectrum is <i>not</i> proportional to the resistive scale, but to the forcing scale.</p><p>2. As intermittency is still an unresolved topic we have looked at the different structure functions of the MHD dynamo. In Paper 6 the longitudinal structure functions based on the Elsasser variables are found to scale like in the model of She & Leveque[2], and the magnetic field is more intermittent than the velocity field. The Elsasser variables have been shown to have a linear scaling of the third order structure function. We do not, however, find the same linear scaling for the individual structure functions of the magnetic and the kinetic field.</p><p>3. In Paper 6 we investigate the growth rate of the magnetic field as a function of magnetic Reynolds number, and we find the critical magnetic Reynolds number as a function of magnetic Prandtl number.</p><p>4. How is the dynamo altered when one imposes an external large scale magnetic field? In Paper 7 we find that an imposed field tend to suppress the dynamo activity on all scales if the field is large enough. For an imposed magnetic field of the same size as the rms velocity field equipartition is found between magnetic and kinetic energy spectra.</p><p>5. Will there be dynamos in supersonic media? One could envisage that the supersonic shock swept up and dissipated the magnetic fields before they got time to grow. Numerical simulations in Paper 8 seem to show that as one increases the Mach number toward unity the critical magnetic Reynolds number increases, but as the Mach number grows even more the critical magnetic Reynolds number stays approximately constant.</p>
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Suneson, Oscar. "Spatial Variability in the Ionosphere and GNSS Signal Delays in the L-band: A Direct Comparison of In-Situ Satellite- and Swepos-Data." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448889.
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It has been shown that ionospheric irregularities can disturb our GNSS (Global Navigation Satellite System) communication. This disturbance is caused by scintillation of the radio signals when they pass through the ionosphere, leading to lock-on difficulties or in worst case, a loss of position for the GNSS-receiver. In this study, a large number of ground based GNSS reference stations spread across Sweden (known as the Swepos-network) was used to measure the variability of the GNSS-signal. These measurements were then combined with observations of ionospheric irregularities made by the Langmuir probes on ESA’s SWARM satellites. The study is a collaboration between Uppsala University and the Swedish Institute of Space Physics and covers five events between December 2013 to Mars 2021, when both datasets were available. The purpose is to determine the shape and extension of these ionospheric irregularities and how localized in time and space they are. The study also tries to answer whether it is possible to draw any conclusions regarding physical models such as diffraction or refraction from this comparison. It was found that during the event days, there was in general a clear increase (of often several hundred percent) of the spatial variability on different scales according to the standard deviation. This increase was seen for both the lower orbiting SWARM A and C satellites and the higher orbiting SWARM B. It was also possible to see that the increase of spatial variability was spread across all the studied latitudes, (magnetic latitude 49° to 70°). This corresponds well with the fact that all the analysed event days had an GNSS-signal variability above average for the same latitudes. There seems to be a clear connection between increased GNSS-signal variability and ionospheric irregularities, although more studies need to be done to be able to draw more accurate conclusions.
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Valan, Vlasta. "Thermal components in the early X-ray afterglow of gamma-ray bursts." Licentiate thesis, KTH, Partikel- och astropartikelfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217103.
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Gamma-ray bursts (GRBs) are still puzzling scientists even 40 years after their discovery. Questions concerning the nature of the progenitors, the connection with supernovae and the origin of the high-energy emission are still lacking clear answers. Today, it is known that there are two populations of GRBs: short and long. It is also known that long GRBs are connected to supernovae (SNe). The emission observed from GRBs can be divided into two phases: the prompt emission and the afterglow. This thesis presents spectral analysis of the early X-ray afterglow of GRBs observed by the {\it Swift} satellite. For the majority of GRBs the early X-ray afterglows are well described by an absorbed power-law model. However, there exists a number of cases where this power-law component fails in fully describing the observed spectra and an additional blackbody component is needed. In the paper at the end of this thesis, a time-resolved spectral analysis of 74 GRBs observed by the X-ray telescope on board {\it Swift} is presented. Each spectrum is fitted with a power-law and a power-law plus blackbody model. The significance of the added thermal component is then assessed using Monte Carlo simulations. Six new cases of GRBs with thermal components in their spectra are presented, alongside three previously reported cases. The results show that a cocoon surrounding the jet is the most likely explanation for the thermal emission observed in the majority of GRBs. In addition, the observed narrow span in radii points to these GRBs being produced in similar environments.<br><p>QC 20171031</p>
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Borgonovo, Luis. "Spectral and Temporal Studies of Gamma-Ray Bursts." Doctoral thesis, Stockholm : Department of Astronomy, Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6793.
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Nymark, Tanja. "X-ray emission from supernova shock waves." Doctoral thesis, Stockholm : Department of Astronomy, Stockholm university, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6671.
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Hayes, Matthew. "Lyman-alpha imaging of starburst galaxies in the local universe and beyond." Doctoral thesis, Stockholm : Department of Astronomy, Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7023.
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Carozzi, Tobia. "Radio waves in the ionosphere : Propagation, generation and detection." Doctoral thesis, Uppsala universitet, Institutionen för astronomi och rymdfysik, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1184.
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We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma.With regards to generation, we will be concerned with three experiments con-ducted at the ionosphere- radio wave interaction research facilities at Sura, Rus-siaand Tromsø, Norway. These facilities operate high power HF transmittersthat can inject large amplitude electromagnetic waves into the ionosphere andexcite numerous nonlinear processes. In an experiment conducted at the Surafacility, we were able to measure the full state of polarization of stimulatedelectromagnetic emissions for the first time. It is expected that by using thetechnique developed in this experiment it will be possible to study nonlinearpolarization effects on powerful HF pump waves in magnetoplasmas in the fu-ture.In another experiment conducted at the Sura facility, the pump frequencywas swept automatically allowing rapid, high-resolution measurements of SEEdependence on pump frequency with minimal variations in ionospheric condi-tions.At the Tromsø facility we discovered by chance a highly variable, pumpinduced, HF emission that most probably emanated from pump excited spo-radicE. Regarding detection, we have proposed a set of Stokes parametersgeneralized to three dimension space; and we have used these parameters in aninvention to detect the incoming direction of electromagnetic waves of multiplefrequencies from a single point measurement.
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Niblaeus, Carl. "The Sun as a laboratory for particle physics." Licentiate thesis, Stockholms universitet, Fysikum, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-143334.
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In the paper attached to this thesis, Paper I, we have calculated the flux of neutrinos that emanate from cosmic ray collisions in the solar atmosphere. These neutrinos are created in the cascades that follow the primary collision and can travel from their production point to a detector on Earth, interacting with the solar material and oscillating on the way. The motivation is both a better understanding of the cosmic ray interactions in the solar environment but also the fact that this neutrino flux presents an almost irreducible background for the searches for neutrinos from annihilations between dark matter particles in the Sun’s core. This interesting connection between neutrinos and dark matter make use of the Sun as a laboratory to investigate new models of particle physics. If dark matter consists of weakly interacting massive particles (WIMPs), the Sun will sweep up some of these WIMPs when it moves through the halo of dark matter that our galaxy lies in. These WIMPs will become gravitationally bound to the Sun and over time accumulate in the Sun’s core. In most models WIMPs can annihilate to Standard Model particles when encountering each other. The only particle that can make it out of the Sun without being absorbed is the neutrino. The buildup of WIMPs in the solar interior can therefore lead to a detectable flux of neutrinos. Neutrino telescopes therefore search for an excess of neutrinos from the Sun. To be able to ensure that a detected flux is in fact coming from dark matter annihilations one must properly account for all other sources of neutrinos. At higher energies these are primarily neutrinos created in energetic collisions between cosmic rays and particles in the Earth’s atmosphere, but also the solar atmospheric neutrinos. The latter will be tougher to disentangle from a WIMP signal since they also come from the Sun. We calculate in Paper I the creation of the neutrinos in the solar atmosphere and propagate these neutrinos to a detector on Earth, including oscillations and interactions in the Sun and vacuum oscillations between the Sun and the Earth. We find that the expected flux is small but potentially detectable by current neutrino telescopes, although further studies are needed to fully ascertain the possibility of discovery as well as how to properly disentangle this from a potential WIMP-induced neutrino signal.
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Eriksson, Simon. "A Photometric Variability Study Using Brown Dwarfs As Giant Planet Analogues : Investigating rotation periods and cloud structure." Thesis, Stockholms universitet, Institutionen för astronomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-152174.
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Rastau, Vlad. "Deathstar." Thesis, Uppsala universitet, Teoretisk astrofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-377146.
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Hultquist, Adam. "Spectral line broadening using ABO theory." Thesis, Uppsala universitet, Teoretisk astrofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-377225.
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Bartilsson, Alexander. "On the possibility of nding exoplanets usinggravitational lensing of radio backgrounds." Thesis, Stockholms universitet, Institutionen för astronomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-166296.
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We propose a new method for detecting exoplanets using gravita-tional lensing. The hypothesis is that the lensing caused by an exo-planet could distort the structures of a radio background, for instancea H II region. It cannot be done with todays telescope but with thesecond incarnation of the Square Kilometer Array (SKA), currently inits design phase we deem it possible. In order to test this hypothesis weconstructed a simulation that creates a simple background structurewith variable scale and then produces simulated images such as theones achievable with the SKA. We produce positive result with a clearsignature of the planet with certain background scales and suggestfurther investigation into this method of detecting exoplanets.
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Husseini, Majid. "Magnetic field strength of chemically peculiar A and B-type stars." Thesis, Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-454565.
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The goal of this work is to detect Zeeman split lines and measure magnetic field strength in a sample of Ap stars. This work aims to analyse spectra of 454 stars and find stars that show spectral lines resolved into their magnetically split components. The work included writing and applying a computer code to visualize astronomical spectra and estimate the mean surface magnetic field strength by fitting resolved Zeeman split lines. The data represent spectroscopic measurements obtained from November 2018 to March 2020 with the HERMES spectrograph. This study investigated high-resolution spectra of 454 Ap stars and identified 31 stars showing resolved Zeeman split lines. The majority of these stars were already known to have resolved magnetically split lines, but this paper reports the discovery of 12 new stars having this property. This paper presents 67 measurements of the mean magnetic field modulus of 31 Ap stars with resolved magnetically split lines.
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Herard, Thomas. "The magnetic fields of exoplanet hostM-dwarf stars : The magnetic fields of exoplanet hostM-dwarf stars." Thesis, Uppsala universitet, Teoretisk astrofysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-455262.
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The majority of stars in the Milky Way are M dwarfs whichmake up 75 % of stars in the vicinity of the sun. As the magneticfield of stars can significantly affect the interiors and theatmospheres of the exoplanets they host within the stellar system,characterising this magnetic field is of major importance.In this work, we selected a sample of 23 exoplanet hostM dwarfs and analysed the observations made by the highresolutionspectropolarimeters ESPaDOnS and NARVAL availablein PolarBase for these stars. In particular, we used theLSD Stokes I and V spectra to measure the projection alongthe line of sight of the average magnetic field over the stellarsurface. 60% of stars had a likely magnetic signatures with adetection greater than 2. By taking the maximum value foreach star over the different observations, the median magneticfield strength measured was 55 G and only a few stars exceeded100 G in strength.
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Robustini, Carolina. "Study of peacock jets observed above a sunspot light-bridge : results and techniques." Licentiate thesis, Stockholms universitet, Institutionen för astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137687.
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Greiselis, Marcis. "Synthetic spectrum calculations of Ca II lines in the Gaia RVS wavelength region." Thesis, Uppsala universitet, Observationell astrofysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355511.
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The Gaia space telescope is dedicated to monitor the sky, collect data and create the most precise 3D map consisting of more than 1.7 billion objects in the Milky Way. At the same time, the Radial Velocity Spectrometer (RVS) will collect spectra for ~150 million stars in the wavelength range 847 to 874 nm. This wave range is selected because it coincides with G-and K-type star energy-distribution peaks, as well as containing the strong Ca II infrared triplet lines (λ =8498, 8542, 8662 Å). The aim of this thesis is to create a grid of synthetic spectra in RVS wavelength range which later when compared to the real spectra can be used to determine the chemical composition of the star as well as precise atmospheric parameters. Calculations consist of 198 spectra ranging in effective temperature from Teff =4500 K to 7000 K with various steps, surface gravity log g = 2.5 to 4.5 with the step of 0.5and metallicities [M/H] = −0.5, 0.0 and 0.5 relative to the Solar composition. For calculations MARCS atmosphere models [3], a line list extracted from the VALD3 database [6] and the software SME [7] was used. Spectra calculations were conducted in both classical LTE and refined non-LTE modes for the line formation of calcium.
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Andersson, Jennifer. "Determination of the Orbit and Dynamic Origin of Meteoroids." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355430.
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One method that can be used to identify the dynamic origin and specific parent bodies of Earth crossing meteoroids is the determination of the meteoroids’ orbital evolution. In this study, a Python-based program using the REBOUND software integration package to integrate meteoroid orbits backwards in time is developed. The program uses data from meteor observations made by the Swedish Allsky Meteor Network, and traces the distance and relative velocity between the meteoroid orbit and the orbits of selected parent body candidates backwards in time. The measure of these orbital differences is known as dissimilarity. The model is used to successfully reproduce the evolution of the Southworth-Hawkins dissimilarity criterion of the Annama meteorite and plausible parent body candidate 2014 UR116 presented by Trigo-Rodríguez et al (2015), as well as to determine plausible parent body associations of several meteors observed by the Swedish Allsky Meteor Network. Plausible parent bodies are presented in two new meteor cases, one of which confirms the parent body of the Geminid meteor shower. The model is concluded to be sufficiently accurate to motivate further use for meteoroid orbit integration purposes, and suggestions for future improvements are made. A new plausible parent body candidate for the Annama H5 meteorite is identified; the asteroid 2017 UZ44. In the case of one meteor event previously identified as a Perseid, the verification of the parent body is not successful using the developed model. In this case, no parent body candidate is found. Possible reasons for this are discussed. Moreover, the observational accuracy is found to be crucial if the program is to be used to study the meteor events observed by the network in detail, as the orbit has to be very well-constrained.<br>En metod som kan användas för att identifiera moderkroppar till meteoroider som äntrar jordens atmosfär är analys av meteoroidbanornas utveckling över tid. I denna studie har ett Python-baserat program som använder det numeriska integrationspaketet REBOUND för att följa meteoroidbanors utveckling över tid tagits fram. Programmet använder data från meteorobservationer som genomförts av det svenska meteornätverket Swedish Allsky Meteor Network och följer meteoroidbanors banutveckling i jämförelse med potentiella moderkroppars banutveckling över tid. För jämförelsen används Southworth-Hawkins-kriteriet. Modellen används för att framgångsrikt reproducera resultat presenterade av Trigo-Rodríguez et al (2015) genom att följa Annama-meteoritens banutveckling jämfört med banutvecklingen hos den möjliga moderkropp som presenteras i studien, asteroiden 2014 UR116. Modellen används också för att hitta möjliga moderkroppar för flertalet meteorer som observerats av det svenska meteornätverket. Möjliga moderkroppar presenteras i två fall, varav ett bekräftar moderkroppen för meteorregnet Geminiderna. Modellen verkar vara tillräckligt bra för att motivera användning vid integration av meteoroidbanor i syfte att identifiera moderkroppar genom att jämföra banornas utveckling över tid. En ny möjlig moderkropp presenteras för Annama-meteoriten; asteroiden 2017 UZ44. I ett fall har en meteor som observerats av det svenska meteornätverket tidigare klassificerats som en Perseid, men beräkningar genomförda med modellen framtagen i denna studie kan inte bekräfta resultatet. I detta fall återfinns ingen möjlig moderkropp för den specifika meteoren. Möjliga anledningar till detta diskuteras. Slutligen dras slutsatsen att mätosäkerheten i meteorobservationerna är vital för att meteoroidens bana ska vara tillräckligt välbestämd för att användas i syfte att analysera meteoroidbanornas utveckling över tid och hitta möjliga moderkroppar.
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Gächter, Sundbäck Dominic. "Analysis of the Hard Spectrum BL Lac Source 1H 1914-194 with Fermi-LAT Data and Multiwavelength Modelling." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76510.
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The very-high-energy gamma-ray emission of the hard spectrum BL Lac source 1H1914-194 has been studied with Fermi-LAT data covering a nearly ten-year period between August 2008 until March 2018 in the energy range of 300 MeV to 870 GeV. The mean flux has been determined as 8.4 x 10-9±3.5 x 10-10 photon cm-2 s-1. The data processing has been done with the Enrico software using the Fermi Science Tools (v10r0p5) and the Pass 8 version of the data, performing binned analysis in order to handle the long integration time. The lightcurve shows that the source has to be considered as variable in the given time period for a three-month binning. It gives furthermore evidence for at least one quiet and active period lasting slightly over 1.5 years each. Even these shorter periods show a weak variability. The significance of the source has been determined as σ = 57.5 for a one-year period. The spectral analysis of three different time periods have been fitted by PowerLaw2, LogParabola and PLExpCutoff functions resulting in LogParabola being slightly favored in most of the cases. However, the test statistic are not showing enough significance that may lead to an unambiguous preference. The data from the analysis has been implemented in a multiwavelength view of the source, showing that the analysis is in agreement with the data coming from the Fermi catalogs. The overall emission of 1H1914-194 has been modelled with theoretical frameworks based on a one-zone Synchrotron Self Compton (SSC) model providing an acceptable description of the SED.
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Hanimeli, Ekim Taylan. "Test Of Cosmological Models With Variable G." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70836.
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Sindel, Jan Philip. "The transmission spectrum of WASP-121b in high resolution with HARPS." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70879.
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Wehrhahn, Ansgar. "Data Reduction and Analysis for Exoplanet Characterization." Licentiate thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-437613.
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Zbinden, Jonas. "Planning Observations of Terrestrial ExoplanetsAround M Type Stars with CRIRES+." Thesis, Uppsala universitet, Observationell astrofysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-437673.
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In recent decades, thousands of exoplanets have been discovered. The next step is to characterize theobserved planets in terms of their radii, masses, density, physical conditions and composition of theiratmospheres. Several space-based observatories such as TESS and CHEOPS have started determiningthe first three observables but characterization of exoplanetary atmospheres is waiting for observationcampaigns with instruments like CRIRES+ at the VLT and NIRSpec on the JWST. To ensure the efficiencyof data acquisition, careful planning of observations is necessary. In this project we developeda software tool to select and rank candidates based on the feasibility of observations of atmosphericfeatures during transits with CRIRES+. We also review different techniques to retrieve transmissionspectra from transit observations and modeling of exoplanet atmospheres in order to clarify the requirementsfor the data. Our CRIRES-planning-tool is built on astronomical observation planningmethods from astropy and astroplan and the exposure time calculator designed for CRIRES+ byESO and UU. We conclude that observations for atmospheric characterization with CRIRES+ are feasible.However, we observed that for a robust candidate selection, careful iterative tuning of proposedconstraints is required.
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Tabera, Martin Luis. "Evolution and properties of planetary systems." Thesis, Uppsala universitet, Observationell astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-438128.
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Liland, Lukas. "Neutrino Emission From Supernovae : At what distance will it kill you?" Thesis, Uppsala universitet, Högenergifysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414990.
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Quinto, Clara. "Extinction of type II supernovae." Thesis, Uppsala universitet, Observationell astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415497.
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Schmidt, Luca. "Formation of Eu II spectral features in magnetic chemically peculiar stars." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-418059.
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The advancing resolution of modern spectrometers uncovers increasingly detailed spectral features in astrophysical observations which can be attributed to properties of the energy structure of the corresponding atomic systems such as fine, hyperfine and Zeeman splitting. At the same time, increasing computational power enables us to include these quantum mechanical interactions on different levels of sophistication in our theoretical atomic structure calculations. This project aims at investigating the hyperfine and Zeeman splitting in five spectral lines of singly-ionized Europium which are relevant for astrophysical studies. To that end, we perform ab initio atomic structure calculations with the latest versions of the code packages Grasp2018 and Rhyze in which we treat the two interactions with a) first-order perturbation theory and b) a generalised full-matrix (`all-order') approach. For both sets of atomic data, we synthesize stellar Stokes I and V spectra for a model atmosphere and stellar magnetic field regime typical for magnetic, chemically peculiar Ap stars. We confirm the overall importance of accounting for hyperfine and Zeeman interactions in the atomic data and find significant differences between the two approaches in the synthesized spectra for the Zeeman interaction. The established computational machinery represents a systematic and largely generalised approach to synthesize spectra of magnetic stars from purely ab initio atomic calculations, including hyperfine and Zeeman interaction simultaneously for any atomic species in the periodic table.
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Galstyan, Irina. "Black-Hole Universe." Licentiate thesis, Stockholms universitet, Fysikum, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-149311.
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In this contribution, we have constructed new analytical solutions for initial data of the Einstein equations. Such solutions are valuable for gaining a better understanding of problems involving strong gravitational and/or electromagnetic interactions in general relativity. In this process, we have examined an inhomogeneous cosmological model consisting a lattice of regularly arranged, charged black holes with initial data corresponding to the maximum expansion of a cosmological solution. We have also refined the method in such a way that the values of the mass and charge of the sources can be prescribed beforehand subject to certain constraints dictated by the field equations.
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Faerber, Timothy. "Large-Scale Structure under Λ-CDM Paradigm". Thesis, Uppsala universitet, Observationell astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414552.
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Cavallius, Maria. "Gas in Debris Disks." Licentiate thesis, Stockholms universitet, Institutionen för astronomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-186017.
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Siderud, Emelie. "Dust emission modelling of AGB stars." Thesis, Uppsala universitet, Observationell astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-423949.
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DUFOUR, Tabatha. "Black holes as standard candles through their Hawking radiations." Thesis, Stockholms universitet, Fysikum, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-194014.
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As they are evaporating, black holes are emitting radiations called Hawking radiations. Our goal is to determine at which distance it is possible to measure those radiations with current telescopes. Being capable of measuring those radiations would mean that we can use them as standard candles i.e. we could use it as distance indicator. To do so, we are first going to compute the different characteristics of a black hole such as its energy peak, temperature, flux and lifetime. Knowing that, we will be able to describe how, theoretically, we could use black holes as standard candles. Finally, we will take the Fermi-LAT telescope as an example of what we can observe in practice and at which distance.
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Fernández, Álvaro. "Neural networks for finding Calabi-Yau metrics." Thesis, Uppsala universitet, Teoretisk fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-447290.
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Gabrielsson, Jonas. "Estimation of satellite orbits using ground based radar concept." Thesis, Umeå universitet, Institutionen för fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-185298.
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Today an abundance of objects are circulating in earth captured orbit. Monitoring these objects is of national security interest. One way to map any object in orbit is with their Keplerian elements. A method for estimating the Keplerian elements of a satellite orbit simulating a ground based radar station has been investigated. A frequency modulated continuous wave radar (FMCW) with a central transmitter antenna and a grid of receivers was modeled in MATLAB. The maximum likelihood estimator (MLE) was obtained to estimate the parameters from the received signal. The method takes advantage of the relations between the Cartesian position and velocity and the Keplerian elements to confine the search space. For a signal to noise ratio (SNR) of 10dB, the satellite was followed during a time period of 0.1s where the positions were found within average error of range: ±1.4m, azimuth: ±2.0·10−6 rad and elevation: ±8.4·10−7 rad. Using a linear approximation of the velocity the Keplerian elements were found within average error of i: ±0.0050 rad, Ω:±0.0050 rad, ω: ±0.0058 rad, a: ±2.60·105m, e:±0.0021 and ν: ±0.24 rad. A method to obtain more accurate estimates is proposed.
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Stergiopoulou, Aikaterini. "Dynamical Stability of Planetary Systems." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-323006.
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The study of dynamical stability in planetary systems has become possible during the last few decades due to the development of numerical methods for long-term integrations of N-body systems. Since the 90’s the number of exoplanet detections has been increased significantly, making the simulations of other real planetary systems besides the Solar System feasible. One of the exciting new-found worlds is the system Kepler-11. Six planets which are located very close to each other orbit a solar-type star. In this project we first investigate the behavior of Kepler-11 when we change some of the initial conditions of the outermost planet of the system and then we approximate the Red Giant phase of solar-type stars in order to see how the planetary orbits are altered. For the first part we run three series of simulations (groups A,B,C). Each group has a different value for the mean density of planet Kepler-11g (1.0,1.5,2.0 g/cm 3 ). We run simulations for 36 different combinations of mass and eccentricity of planet Kepler-11g for each group. In nine configurations all six planets of the system continue to orbit the star until the end of the simulations. These nine stable configurations of Kepler-11 are used in the second part where we implement a constant mass-loss rate for the star which results in 30% mass loss after 30 million years, trying to approximate that way the mass loss of solar-type stars in Red Giant Branch. We also run nine simulations of a hypothetical system consisting only of the Sun, Earth and Jupiter where we implement the constant mass-loss rate to the Sun. In the Kepler-11 system, the orbits of planets Kepler-11g and Kepler-11e change by ∼45% and ∼54% respectively, after 30 million years, due to the mass loss of the star, while in the hypothetical planetary system the orbits of the two planets change by ∼43%. The study of orbits and how they move outward during the Post-Main Sequence evolution of stars is essential for our understanding of the existence of a Habitable Zone, not just around stars in Main-Sequence phase, but also around stars in late stages of their evolution.
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Bello, Arufe Aaron. "Gravitational Waves in General Relativity." Thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-136721.
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In this paper, we write a summary about general relativity and, in particular,gravitational waves. We start by discussing the mathematics that generalrelativity uses, as well as the geometry in general relativity's spacetime. Afterwards,we explain linearized general relativity and derive the linearizedversions of Einstein's equations. From here, we construct wave solutionsand explain the polarization of gravitational waves. The quadrupole formulais derived, and generation and detection of gravitational waves is brie ydiscussed. Finally, LIGO and its latest discovery of gravitational waves isreviewed.
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Romero, Daniela. "Comparing the Period-Luminosityrelationships in variable stars." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-323634.
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There are four Period Luminosity relations from three sources, [3, 5, 9, 11], that are compared for theiraccuracy in calculating distances and to see how much uncertainty has to be considered when calculatingother distances based on these. Here, the relations are compared by using each to calculate and compare thedistances of the stars: BK Vir, L2 Pup, R Hor, R Hya, R Lep, and RR Aql; along with using data from AAVSOand SIMBAD in the calculations. The relations have an uncertainty that ranges from about 30%-40%, exceptfor the relation from [9] that has an uncertainty of 90%
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Björk, Kevin. "Fluctuations in the CMB through inflation." Thesis, Uppsala universitet, Teoretisk fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-323636.
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The goal of this project is to gain a better understanding of the temperature fluctuations observed in the CMB. This goal is reached with the aid of a literature study. The report touches upon the origin of the CMB as well as how it is measured, mentioning and explaining relevant concepts such as recombination, photon decoupling, black body radiation, angular power spectrum etc. It is also specified that the temperature of the CMB is not uniform but varies slightly. The fact that these fluctuations show inhomogeneities at the early universe is emphasized as well as the need for a satisfying theory that explains said fluctuations. By presenting and employing inflation theory in combination with quantum mechanics, we show how such a theory can be obtained. Through extensive calculation we show how the primordial power spectrum for zero-point fluctuations during inflation is obtained and how it can be related to the time of recombination through a transfer function, thus explaining the existence of fluctuations in the CMB.<br>Målet med detta projekt är att få en bättre förståelse om observerade temperaturfluktuationer i CMB. Detta mål är uppnått med hjälp av en litteraturstudie. Rapporten nämner uppkomsten av CMB samt hur den mäts, nämner och förklarar relevanta koncept som rekombination, foton frikoppling, svartkroppstrålning, vinkelkraftspektrum etc. Det är också specificerat att temperaturen av CMB inte är enhetlig utan varierar en aning. Faktumet att dessa fluktuationer visar på inhomogeniteter i det tidiga universum är betonat samt behovet av en tillfredställande teori som förklarar dessa fluktuationer. Genom att presentera och använda inflationsteori i kombination med kvantmekanik visar vi hur en sådan teori kan erhållas. Genom omfattande beräkningar visar vi hur det ursprungliga kraftspektrumet för nollpunktsfluktuationer under inflation är erhållet och hur det kan relateras till tiden för rekombination genom en överföringsfunktion, som således förklarar existensen av fluktuationer i CMB.
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Laraña, Aragón Jorge. "Counting Black Hole Microstates in String Theory." Thesis, Uppsala universitet, Teoretisk fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-330148.
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In this project, we explore the area of black holes in String Theory. String Theory has had several successes in describing properties of black holes. Recent progress in String Theory points towards the possibility that black holes should not be thought of as fundamental objects, but rather as statistical descriptions of a huge number of smooth horizonless microstate geometries. We study this deep connection between the microscopic description of black holes and String Theory. The main goal is to understand and learn how some of the modern techniques in String Theory can be applied to model black holes, in particular, calculating an expression for the entropy. The main idea is to construct black hole solutions from intersecting certain types of branes, in the context of Supergravity theories that emerge as low-energy limits of Superstring theories. With this microscopic approach, the aim is to count the number of microstates and then compare with the macroscopic Bekenstein-Hawking entropies. We plan to construct such solutions, for both supersymmetric and non-supersymmetric black holes. Also, this microscopic origin of the black hole entropy could provide new insights to the black hole information paradox.<br>I detta projekt behandlar vi svarta hål i strängteori. Svarta hål är några av naturens mest fascinerande objekt. De är indirekt observerade, som mörka objekt av stjärnstorlek, vilka finns i binära system, eller som supermassiva objekt i galaxers centra. Svarta hål är vanligare förekommande i universum än vad vi tidigare har trott. Uppskattningsvis finns 100 miljoner mörka objekt enbart i Vintergatan. Svarta hål dyker upp i allmän relativitetsteori som klassiska materielösningar som gravitationellt har kollapsat till en punkt, en \textit{singularitet}.Från en teoretisk synvinkel förser svarta hål oss med laboratorier för tankeexperiment, där nya teoretiska ideér kan testas. 1976 upptäckte Stephen Hawking att svarta hål inte är så svarta - de sänder ut värmestrålning motsvarande en karaktäristisk temperatur, Hawking-temperaturen. Termiska egenskaper, såsom Bekenstein-Hawking-entropi, associerades nu med svarta hål. 1996 härleddes denna entropi med strängteoretiska metoder. Man bestämde de mikroskopiska frihetsgraderna för ett speciellt slags svarta hål, och sedan dess har strängteori skördat många framgångar inom forskningsområdet. Här studerar vi detta djupa samband mellan strängteori och den mikroskopiska beskrivningen av svarta hål. Huvudmålet är att förstå hur vissa moderna strängteoretiska tekniker kan appliceras på svarta hålmodeller, framför allt när entropin ska beräknas.
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Törnkvist, Robin. "Vorticity and Gravitational Wave Perturbations on Cosmological Backgrounds Using the 1+1+2 Covariant Split of Spacetime." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-152472.
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In this thesis we consider perturbations of a perfect fluid on locally rotationally symmetrical (LRS) class II cosmological backgrounds, with a nonvanishing vorticity of the fluid on the perturbed model. The method used is based on the 1+1+2 covariant decomposition of spacetime, motivated by the assumption of anisotropic expansion, followed by a harmonic decomposition of all gauge invariant quantities. All perturbed quantities can be solved for in terms of the time evolution equations of eight harmonic coefficients. This set of eight harmonic coefficients decouple into an even and odd sector, containing five and three variables respectively, where the vorticity is represented as one variable in each sector. We find that the time evolution of the vorticity completely decouples from the other perturbed variables, and can be solved exactly by assuming a linear equation of state. The evolution of the remaining perturbed variables are examined in the geometrical optics approximation, and compared to research looking at the case when the vorticity vanishes on the perturbed model. The results turn out to be the same, except for a source term containing the odd parity of the vorticity in the evolution of the density, which act as a source term for the shear waves. The four remaining variables will represent damped, source free gravitational waves.
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Nebrin, Olof. "Cosmic Dawn in a Fuzzy Universe : Constraining the nature of Dark Matterwith 21 cm Cosmology." Thesis, Stockholms universitet, Institutionen för astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-154861.
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The cold dark matter (CDM) paradigm underlying the standard <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5CLambda" />CDM model of cosmology is successful on large scales but faces potential problems on small scales partly related to a seeming overproduction of dwarf galaxies. This could be alleviated in exotic dark matter models that suppresses small-scale structure formation. One such attractive model is known as fuzzy dark matter (FDM). FDM positsthat dark matter is composed of ultra-light bosons with masses <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?m_%7B%5Crm%20FDM%7D%20%5Csim%2010%5E%7B-22%7D" /> eV. With such light particle masses, quantum effects become important. More specifically, a pressure-like term appears in the equations of motion that counteracts gravitational collapse on small scales. Because small galaxies form first in CDM, it follows that the early history ot galaxy formation predicted by FDM should be markedly different. One novel way to probe this effect would be to use the 21 cm line of hydrogen which acts as a sensitive probe of the epoch of reionization (EoR) and Cosmic Dawn — when the first galactic sources of X-rays started to reheat theintergalactic medium (IGM). In this thesis, the evolution of the 21 cm signal have been simulated for both CDM and FDM. These simulations indicate that the fluctuationsin the 21 cm signal amenable to future observations are extremely weak (<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cll" /> 1 mK) — and probably unobservable — for FDM at high redshifts <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?z%20%5Csim%2015-16" /> compared to CDM (which tend to yield signals with amplitudes <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cgg" /> 1 mK). This is mainly due to the delayed galaxy formation in FDM resulting in delayed Lyman-<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Calpha" /> coupling of the 21 cm spin temperature to the kinetic temperature of the IGM. A robust prediction from all FDM scenarios explored in this thesis is that any detection of a signal at <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?z%20%5Csim%2015-16" /> would rule out interesting particle masses for FDM, and would be evidence for CDM-like structure formation. Future work that properly models ionization fluctuations during the EoR could also yield strong predictions at lower redshifts.
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Rivero, Losada Illa. "Effects of rotation and stratification on magnetic flux concentrations." Licentiate thesis, Stockholms universitet, Institutionen för astronomi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-112879.
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The formation of magnetic flux concentrations in the Sun is still a matter of debate. One observable manifestations of such concentrations is sunspots. A mechanism able to spontaneously form magnetic flux concentrations in strongly stratified hydromagnetic turbulence and in the presence of a weak magnetic field is the negative effective magnetic pressure instability (NEMPI). This instability is caused by the local suppression of the turbulence by the magnetic field. Due to the complexity of the system, and in order to understand the fundamental physics behind the instability, the study started by considering simplified conditions. In this thesis we aim to move towards the complexity of the Sun. Here we want to know whether the instability can develop under rotation and in the case of a polytropic stratification instead of the simpler isothermal stratification. We perform different kinds of simulations, namely direct numerical simulations (DNS)and mean field simulations (MFS) of strongly stratified turbulence in the presence of weak magnetic fields. We then study separately the effects of rotation and the change in stratification. It is found that slow rotation can suppress the instability. For Coriolis numbers larger than $0.1$ the MFS no longer result in growth, whereas the DNS start first with adecreaseof the growth rate of the instability % with the speed-up of rotation is alleviated and then, for $\Co > 0.06$, an increase owing to the fact that rotation leads to the onset of the dynamo instability, which couples with NEMPI in a combined system. In fact, the suppression implies a constraint on the depth where the instability can operate in the Sun. Since rotation is very weak in the uppermost layers of the Sun, the formation of the flux concentration through this instability might be a shallow phenomenon. The same constraint is found when we study the effects of polytropic stratificationon NEMPI. In this case, the instability also develops, but it is much more concentrated in the upper parts of the simulation domain than in the isothermal case. In contrast to the isothermal case, where the density scale height is constant inthe computational domain, polytropic layers decrease their stratification deeper down, so it becomes harder for NEMPI to operate. With these studies we confirm that NEMPI can form magnetic flux concentrations even in the presence of weak rotation and for polytropic stratification. When applied to the Sun, the effects of rotation and the change of stratification constrain the depth where NEMPI can develop to the uppermost layers, where the rotational influence is weak and the stratification is strong enough.
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Menacho, Veronica. "The violent ISM in Haro 11." Licentiate thesis, Stockholms universitet, Institutionen för astronomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-163310.
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This thesis introduces briefly physical processes operating in the ISM around massive starsand focuses on the impact strong stellar feedback has in creating large-scale structures in a galaxy.Stellar feedback is ubiquitous in star forming galaxies and its effect on the ISM depends strongly on the energy output from the most massive stars (M$\geq$7 \Mo ) and the properties of the surrounding gas. Starburst galaxies are among the most active in producing %galaxies are among the most active galaxies and produce a large amount of massive star clusters %or even super star clusters (SSC; M$_{cl} \geq 10^5$ \Mo ), with stellar populations up to thousands of massive stars. %The most massive stars (M$\geq$30 \Mo ) are lives short, but they In the first 4 Myr of the star clusters evolution, radiative feedback of the most massive stars (M$\geq$30 \Mo ) are at work. Large amount of ionizing photons are released to the ambient medium while radiative pressure compress the surrounding gas. At the same time their stellar winds inject continuously mechanical energy and momentum in their surrounding. This mechanical feedback is then at later ages, until $\sim$ 40 Myrs, maintained by supernova explosions from the less massive stars. Strong stellar feedback tends to develop large-scale structures such as bubbles, loops, filaments and outflows. These are transient structures and can be seen as imprints of how the released energy is clearing or has cleared paths in the ISM. Strong stellar feedback can have devastating consequences in dwarf galaxies due to their shallow gravitational potential. It can accelerate outflows with velocities larger than their escape velocities. In this way, dwarf galaxies can lose a large fraction of their gas mass, which will be crucial in their subsequent evolution.On the other hand, galactic winds might be responsible to create holes in the ISM, allowing the easily-absorbed ionizing photons (Lyman continuum photons, LyC) to escape the galaxy. Studies on a few LyC leaking galaxies have shown that this mechanisms might have preference from a density-bound scenario, which takes place in galaxies with a highly ionized halo. In my paper I used deep MUSE observations to analyse the impact strong stellar feedback has in the starburst and Lyman continuum emitting galaxy: Haro 11. The paper presents three emission line diagnostics aiming to analyse the condition of the warm ionized gas in this galaxy, which are the \Ha\ emission, the level of ionization in gas and the presence of fast shocks. These diagnostics are presented in maps of 50 \kms\ bins in a velocity range from -400 to 350 \kms . Haro 11 shows a violent ISM whose warm ionized gas is almost completely shaped by effect of stellar feedback from the most massive star forming regions in the centre. Arcs, shells, outflows paths and galactic scale ionizing cones are imprinted in ISM of Haro 11. Our analysis suggests the presence of a kpc-scale superbubble which might have created galactic holes in the ISM. Beside of that, Haro 11 shows a highly ionized halo. Both mechanisms appear to facilitate the escape of LyC in this galaxy. %Finally, we observe emission at velocities up to thousand \kms\ which could hints to gas escaping the galaxy. Finally the paper presents estimates of the gas mass fraction that could escape the gravitational potential of the galaxy.
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Risberg, Nicolas. "Weak Lensing of Type Ia Supernovae." Thesis, Stockholms universitet, Institutionen för astronomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-169516.
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Studying weak gravitational lensing of type Ia supernovae is a valuable tool to have in cosmology. Gravitational lensing may amplify the brightness of the source, affecting the brightness distribution of observed supernovae in a non-Gaussian way. Testing this magnified distribution for normality may thus reveal the observation of weak lensing. Simulation of lensing and studying the feasibility of current telescopes (ZTF) detecting it gives a first look into when this mechanism may be fully utilized.
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Granqvist, Elvira. "Approximating general relativistic effects in Newtonian hydrodynamic supernova simulations." Thesis, Stockholms universitet, Institutionen för astronomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-169517.
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In this research, the validity of using an effective potential to approximate general relativistic effects in an otherwise Newtonian setting was investigated, by making simulations of core collapse supernovae on one hand in full general relativity, and on the other hand in said Newtonian setting. This was done for a mass range covering progenitors of 12 − 60 solar masses; a much wider mass range than has been used in earlier research, that also includes progenitors that form black holes. Two numerical codes were used; the general relativistic hydrodynamic code GR1D, and the Newtonian hydrodynamic code FLASH. For simplicity, spherical symmetry was assumed, and a M1 neutrino transport was employed rather than solving the full Boltzmann transport equation for neutrinos. Three different versions of the effective potential; GREP1, GREP2, and GREP3, were tested, and their results compared to a general relativistic case; GR, in an attempt to investigate possible improvements of earlier research. For all parameters investigated in this research, case GREP1 (and GREP2) yielded results that agreed very well with case GR at the time around bounce, though somewhat worse later on in the evolution. This observation is consistent with that made by Marek et al. (2006), but for a much larger set of progenitors, and therefore, the reliability of using this version of the effective potential to approximate general relativistic effects in an otherwise Newtonian setting, is not only confirmed, but extended as well. Another exceptional result not seen before was the black 1 hole formation times, which all three effective potentials could reproduce within ∼ 5% compared to case GR. In addition to this, case GREP3 yielded excellent results for the central density, but rather poor results for the remaining properties, and is thus not recommended to use to approximate general relativistic effects, although further investigation of this potential might give valuable clues for further improvements
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Zylinski, Karl. "Finding new atomic-diffusion stellar laboratories with Gaia and GALAH." Thesis, Uppsala universitet, Observationell astrofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388455.
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Gullin, Samuel. "What powered the unusual supernova iPTF15eov?" Thesis, Stockholms universitet, Institutionen för astronomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-170299.
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Imaz, Inigo. "The search for CC SN in unobscured AGN." Thesis, Uppsala universitet, Observationell astrofysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297458.
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