Pathfinding Fast Radio Bursts Localizations using Very Long Baseline Interferometry
Bibliographic record
Abstract
Fast radio bursts (FRBs) are millisecond-duration, bright radio transients of extragalactic origin. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope’s CHIME/FRB instrument and other radio telescopes across the globe have detected hundreds of FRBs. Their origins are a mystery. Precise localization within the host is critical to distinguish between progenitor models. This can be achieved through Very Long Baseline Interferometry (VLBI). Until now, VLBI localizations have only been carried out in targeted follow-up observations of some repeating sources which comprise a small fraction of the FRBs. For this work, an interferometric array of 6m dishes was constructed at the Green Bank Observatory as a pathfinder to develop the necessary systems, technology, and techniques to enable VLBI on FRBs. This array called TONE has 8 instrumented dishes and works as a VLBI outrigger for CHIME on a \SI{\sim3300}{\kilo\meter} baseline. This involved construction, commissioning, and integration of the custom analog chains and digital system. TONE is pointed to shadow a portion of the CHIME primary beam at a fixed declination of \SI{22}{\deg}. Upon detection of a single dispersed pulse such as an FRB or a giant pulse from the Crab pulsar, CHIME alerts TONE, triggering a recording of buffered data to disk. In addition to TONE, a single 10-m dish at Algonquin Radio Observatory (ARO10) is set up with a similar infrastructure. Together they form the pathfinders for conducting VLBI for FRBs. We used these VLBI pathfinders to localize FRB 20210603A at the time of detection. The baseband data from CHIME and TONE are used to synthesize single beams at each telescope. The single-beam data from TONE and data from ARO10 are each cross-correlated with the single beam data from CHIME. We use the Crab pulsar for astrometric calibration and additionally correct for clock errors. The calibrated and corrected cross-correlated data is sampled with a likelihood function of the sky location and ionospheric effects using a Markov Chain Monte Carlo method to estimate the Right Ascension and Declination of the FRB. We localize the burst to SDSS J004105.82+211331.9, an edge-on quiescent lenticular galaxy at redshift z $\approx 0.177$. The localization, dispersion measure, rotation measure (RM), and temporal broadening are consistent with an observed line-of-sight through the host galactic disk, suggesting a progenitor from a population coincident with the host galactic plane. The development of the TONE telescope has enabled the localization of the FRB within the host. This is a key stepping
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".