Bibliographic record
Abstract
The matter content of the Universe is dominated by dark matter. Beyond its abundance and its lack of non-gravitational interactions with standard model matter, little is known about the nature of dark matter. This thesis attempts to illuminate different aspects of dark matter by using gravitational lensing in conjunction with other cosmological probes. Gravitational lensing describes the deflection of light by gravitational potentials and is a direct and unbiased probe of the matter distribution in the Universe. We investigate the weakly interacting massive particle (WIMP) model of dark matter by performing a tomographic and spectral cross-correlation between weak gravitational lensing from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), Red Cluster Sequence Lensing Survey (RCSLenS), and Kilo-Degree Survey (KiDS), and gamma rays from Fermi-LAT. The non-detection of a correlation allows us to constrain the allowed masses, annihilation cross-sections, and decay rates of WIMP dark matter. Even though most matter in the Universe is dark matter, about 16% is baryonic matter. To make precision measurements of the dark matter distribution with gravitational lensing, it is therefore necessary to understand the behaviour and distribution of baryonic matter. We measure and analyse the cross-correlation between weak gravitational lensing from RCSLenS and the thermal Sunyaev-Zeldovich (tSZ) effect from the Planck satellite to constrain the effect of baryon physics on the matter distribution. Models of gravitational lensing often make use of a range of approximations. We study the effect of dropping these approximations on the cross-correlation between gravitational lensing and tSZ by performing a detailed calculation up to fourth order in the gravitational potential. We find that the common approximations are sufficiently accurate even for future surveys. Finally, we explore the growth of structure and the effect of residual weak lensing systematics in a tomographic cross-correlation between weak gravitational lensing from KiDS and lensing of the cosmic microwave background (CMB) from Planck.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".