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. / 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.

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%

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. / 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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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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A small report that investigates neutrino emission from supernovae, in order to estimate at what distance you will have to be from a supernova for the neutrino radiation to kill you.

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