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Research topics - different intensities at Licencjat/Magister/Doktorat level

Non-perturbative N-body/GR simulations

mag/lic, astronomia/fizyka matematyczna

N-body simulations (e.g. AstroPh:0411043, ArXiv:1105.1082, AstroPh:0111367) used for the modelling of 0.1 to 5 Gpc scale structure formation assume a rigid Friedmann-Lemaitre-Robertson-Walker (FLRW) background against which perturbations grow according to Newtonian gravity, while the FLRW background itself evolves assuming that structure formation do not form. An UMK-Lyon project is underway to develop relativistic methods of correcting N-body simulations for this contradiction, by using scalar averaging (AstroPh:9912347, ArXiv:0707.2153, ArXiv:0803.1401, ArXiv:1203.6263, ArXiv:1303.6193). The main result of the full project (ArXiv:1706.06179) is that more accurate simulations help show that "dark energy" is a misinterpretation of the virialisation epoch, during which much of the most massive galaxies and galaxy clusters formed. The student's contribution would be in checking caveats of this calculational method and/or proposing extensions.

Measuring metric inhomogeneity with BAO

mag/lic, astronomia/fizyka matematyczna

The Universe is not homogeneous, but the Concordance Model starts with a spatially-homogeneous solution to the Einstein field equations and afterwards applies perturbations. The scalar averaging approach (AstroPh:9912347, ArXiv:0707.2153, ArXiv:0803.1401, ArXiv:1203.6263, ArXiv:1303.6193) proposes a relativistically more realistic approach to cosmological modelling. The initial measurement of a shift of about 6% in the baryonic acoustic oscillation (BAO) peak location (ArXiv:1410.1687) in overdense regions provides the first tentative evidence of metric inhomogeneity. The calculations using the presently available software are cpu-intensive. A student would help develop algorithmic speedups, tests of the different software modules, and possibly GPGPU modules under OpenCL.

Obserwacje efektu Suniajewa-Zeldowicza w gromadach galaktyk przy użyciu odbiornika OCRA/RT32

mag, astronomia

Obserwacje gromad galaktyk to jeden z głównych nurtów współczesnej kosmologii obserwacyjnej i astrofizyki. Celem pracy jest rekonstrukcja parametrów komptonizacji w gromadach galaktyk obserwowanych 32-m radioteleskopem w ramach projektu OCRA-SZ. Obserwacje radiowe w połączeniu z obserwacjami promieniowania X z satelity Chandra i/lub XMM-Newton umożliwiają rekonstrukcję parametrów fizycznych ośrodka międzygalaktycznego takich jak profil temperatury, profil gęstości, masę, frakcję materii barionowej itp., a to pozwala testować zgodność przewidywań standardowego modelu kosmologicznego z obserwacjami.

Magistrant pozna szczegóły obserwacji efektu Suniajewa-Zeldowicza (SZ) na falach centymetrowych oraz nauczy się analizować dostępne obserwacje rentgenowskie celem wyznaczania podstawowych parametrów ośrodka międzygalaktycznego. Narzędzia programistyczne: c++, Python.

Student(ka) skonsultował(a)by także z Bartkiem Lwem.

Efekty systematyczne w pomiarach gęstości strumienia przy użyciu odbiornika pracującego na falach centymetrowych.

mag/lic, astronomia

Pomiary gęstości strumienia źródeł astronomicznych 32-m radioteleskopem (RT32) obarczone są różnego rodzaju efektami systematycznymi, które należy uwzględnić przy redukcji danych obserwacyjnych. Celem pracy jest analiza istniejących danych obserwacyjnych z odbiornika OCRA/RT32 oraz pomierzenie najważniejszych obserwacyjnych efektów systematycznych (takich jak krzywa wzmocnienia anteny w funkcji elewacji), wyznaczenie parametrów wiązki głównej i listków bocznych, oraz optymalizacja pracy odbiornika wykorzystującego przełączanie wiązek.

Licencjant/Magistrant nauczy się mierzyć gęstości strumienia słabych radio źródeł odbiornikiem OCRA/RT32, redukować dane obserwacyjne, oraz pozna szczegółowo zasady działania całego systemu odbiorczego OCRA oraz podstawy systemu sterowania RT32.

Student(ka) skonsultował(a)by także z Bartkiem Lwem.

STOPINCLUDE is just above this line

już ktoś robi...

źródło: LambdaStudentTematAbstrakt

Czy ,,stała kosmologiczna" jest tylko efekt uśrednienia niejednorodności?

Is the cosmological constant just the result of inhomogeneities?

See e.g. Buchert et al. GrQc:0210037, GrQc:0210045, AstroPh:9609036


"Stary" does not necessarily mean the topic is no longer open. It only means that I (Boud) do not see it as a good student topic that I am interested in supervising right now.

The averaging problem

(todo: rewrite) How significant are the errors introduced by the FLRW approximation? See e.g. Buchert et al ArXiv:0803.1401, ArXiv:1103.2016; Wiltshire ArXiv:0912.5234; Krasinski et al ArXiv:0903.4070, ArXiv:1102.1449. Check at least one of these calculations at the level appropriate for your level of studies.

Topology of the Universe Detection

  • In, it seems that we may have measured the shape of the Universe, since certain parts of the cosmic microwave background seen by the WMAP satellite appear to be seen twice in different directions on the sky, due to topological lensing. The purpose of the masters/licencjat project is:
  • Aim: Propose and apply a further test using WMAP data which further tests the hypothesis. This requires:
    • Reading/writing/managing the WMAP data file with free software computer programs
    • Statistical analysis
    • Independently checking that the computer code does the algebraic and statistical analyses correctly

źródło: LDMStudentTematAbstrakt

Dark Matter - Light Dark Matter (LDM) hypothesis - Galaxy Centre INTEGRAL results

CMB/WMAP/Planck - the Missing Fluctuations problem

mag/lic, astronomia/fizyka matematyczna

WMAP data are too homogeneous on the largest scales to match the infinite flat model, e.g. see Copi et al. 2009 ArXiv:0808.3767, ArXiv:1201.2459, ArXiv:1103.3505. Summarise the evidence; discuss the correlation function versus spherical harmonic interpretations of the data; list possible explanations, including the topology of the Universe as discussed by Karl Schwarzschild, Leopold Infeld, et al.

Topology of the Universe

mag/lic, astronomia/fizyka matematyczna

If you are interested in cosmic topology and have good software skills and/or a good understanding of differential geometry, many interesting observational and theoretical projects are available upon consultation - start reading at MonographCosmo.

Clusters, Lambda, and OCRA/SZ Effect

mag/lic, astronomia/fizyka matematyczna

The largest gravitationally collapsed (virialised) objects in the Universe are clusters of galaxies. In principle, these should be easy to use as cosmological tracer objects in various ways. The simplest interpretation of clusters observed by XMM-Newton using the apparent gas fraction at the virial radius appeared to support a high-density (e.g. zero cosmological constant) model - Sadat et al. 2005 AstroPh:0503426, in contradiction to the Concordance Model. Resolving this contradiction may lead to new understanding of the dynamics and outer parts of clusters, e.g. Kay et al. 2007 AstroPh:0611017, Ferramacho, Blanchard 2007 AstroPh:0609822. Estimate what role RT4/OCRA-f and RTK could play in testing our understanding of clusters.

Dark Matter (DM)

mag/lic, astronomia/fizyka matematyczna

Summarise the evidence; list different types of explanations; give arguments for and against the different candidates; investigate the evidence numerically and produce your own plots. In particular,
  • the Light Dark Matter hypothesis AstroPh:0507142 seems very interesting (is the 511 keV line emission in the galactic centre due to annihilating LDM?); and
  • the DAMA/NaI and DAMA/LIBRA results are interesting - see Bernabei et al. (2008), ArXiv:0804.2741 "the presence of Dark Matter particles in the galactic halo is supported, on the basis of the DM annual modulation signature, at 8.2 σ C.L." and Savage et al. (2009), ArXiv:0808.3607 and references therein;
  • the CDMS (Cryogenic Dark Matter Search) initial results look exciting.
  • could DM be an artefact induced by not applying general relativity correctly? see Buchert & Wiegand ArXiv:1002.3912
  • Warning: microlensing (OGLE etc.) so far only gives evidence of that DM is (mostly) not composed of stellar-mass MACHOs e.g. AstroPh:0607207.

Cosmic String Detection

źródło: DAMAStudentTematAbstrakt

Dark Matter Detection - DAMA/NaI + Foot et al.

  • In the 7 year results of the DAMA/NaI dark matter direct detection experiment show a signal significant at 6.3σ according to the authors. An explanation for why a signal from mirror-baryonic matter should be expected in this experiment but not in others with similar cross-section detection parameters is presented in AstroPh:0403043, see also AstroPh:0407623 and references therein.
  • Aim: Check the experimental and theoretical claims and propose further tests
    • Try to find an alternative explanation for the DAMA/NaI results without going beyond the Standard Model of particle physics
    • Check whether the Foot et al. calculations of mirror matter properties are consistent with all the experimental data as the authors claim
    • Extend the Foot et al. calculations to find, e.g. a non-gravitational effect of mirror matter in stellar physics, e.g. symbiotic stars (gravitational effects of dark matter are already well studied)
  • More info:
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Topic revision: r26 - 01 Jan 2018, BoudRoukema
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