Bibliographic record
Abstract
The radio sky spans tens of orders of magnitude in length, density, and time.In this thesis, using novel filtering techniques and two different telescopes,we investigate two tracers of cosmic structure: Baryon Acoustic Oscillations(BAOs) and Fast Radio Bursts (FRBs). BAOs formed as the universe cooledafter the Big Bang. BAOs provide a fiducial length scale of the universethroughout cosmic time and thus can be used to understand how the universeis evolving. FRBs are very bright, short timescale, bursts of as-yet unknownorigin which occur uniformly on the sky at a rate of a few thousand per day.Now robustly identified with host galaxies in the redshift range 0 < z < 1,FRBs are promising probes of cosmology and fundamental physics and providea new means to probe large-scale structure.Both of these projects suffer from radio frequency interference, anthropomorphic radio energy received by radio telescopes. These signals can besignificantly brighter than the radio sky, obscuring or degrading observationsof signals that are astrophysical in origin. We discuss how this interferencenegatively impacts these experiments and present filtering strategies to eliminate these signals and enhance our sensitivity.The Canadian Hydrogen Intensity Mapping Experiment (CHIME) probesthe large-scale structure of the universe by mapping the 21 cm line fromneutral hydrogen (HI) in the redshift range 0.8 < z < 2.5. We used HIintensity maps produced by the CHIME telescope cross correlated with anoptical survey of galaxies known as WiggleZ. We discuss why, as expected, thiscross correlation fails while other correlations succeed. The cross correlationmethodology is a step towards detecting the large-scale structure with onlythe CHIME intensity map. Particularly, CHIME cosmology aims to detectBAOs. These maps can be used to understand the density power spectrumas well as constraints on fundamental physics, such as neutrino mass.Finding FRBs is of interest to understand their progenitors, which arelikely to be highly relativistic objects (for example, strongly magnetized neutron stars) at cosmological distances. Although individual events last only afew milliseconds, FRB searches require thousands of hours to detect a statistically meaningful sample. In this context, we describe GREENBURST areal-time giant pulse search running on the Green Bank Telescope and presentthe latest constraints it is making to the all-sky FRB rate, which we measureto be 1120+320−270 bursts per day with flux densities above one Jansky. As partof this work, we present GREENBURST discoveries of PSR J0038+54, a 2.2 spulsar in the Galactic field, and FRB 220718, a new transient radio sourcewhich exhibits an 851 ms periodicity within the
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".