Thesis supervisor: István Csabai
co-supervisor: András Kovács
Location of studies (in Hungarian): ELTE Department of Physics of Complex Systems and Research Centre for Astronomy and Earth Sciences (CSFK) Abbreviation of location of studies: ELTE
Description of the research topic:
An over-arching goal of cosmology is a reconstruction of how minuscule density fluctuations seen in the cosmic microwave background (CMB) anisotropies grow to the intricate cosmic web. The consensus ΛCDM (Lambda-Cold Dark Matter) cosmological model has shown remarkable explanatory power over a variety of cosmic scales and epochs, and it narrates a reassuring story of a universe currently filled mostly with dark matter and dark energy. Yet, this explanation is not fully satisfactory, because the actual nature of the dark components remains a puzzle. In this PhD project, we propose to develop new tools to comprehend the elusive dark energy component by using state-of-the-art galaxy and quasar survey data sets. The student will probe the growth rate of structure in extreme environments near density peaks traced by powerful QSOs, as well as in dark and empty voids. In particular, we will study in detail how dark energy stretches the largest cosmic superclusters and the vast voids, spanning about 300 million light-years, leaving smoking-gun evidence in the form of secondary hot and cold spots on CMB temperature/lensing anisotropy maps. We will entertain an emerging new hypothesis that recently reported cosmological anomalies, concerning the delicate balance of expansion and structure growth, might be explained if the expansion of the Universe is inhomogeneous, in contrast with the core assumption of the concordance model. The main goal of the planned 4-year program is to make decisive cross-correlation measurements of super-structures and the CMB in un-probed, key redshift ranges, where the standard and alternative models of dark energy differ most significantly (z > 1). Groundwork results from the SDSS/BOSS, Pan-STARRS, and DES surveys put our collaborating cosmology research group at ELTE and CSFK in a strong position to lead the planned new LSST-DESC, Euclid, J-PAS, and WEAVE-QSO analyses. With these new probes of the cosmic web, we will determine whether some as-yet unknown physical effects or systematic biases complicate the picture. Either way we will gather new knowledge about the Universe on the largest scales.
Required language skills: English Further requirements: MSc degree in Physics
Number of students who can be accepted: 1
Deadline for application: 2024-05-31
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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