Spectrum and polarization of the Galactic center radio transient ASKAP J173608.2-321635 from THOR-GC and VLITE
Bibliographic record
Abstract
The radio transient ASKAP J173608.2-321735, at the position (l,b)= (356.0872,-0.0390), was serendipitously observed by The HI/OH/Recombination Line Survey of the Galactic Center (THOR-GC) at three epochs in March 2020, April 2020 and February 2021. The source was detected only on 2020 April 11 with flux density 20.6 +/- 1.1 mJy at 1.23 GHz and in-band spectral index alpha = -3.1 +/- 0.2. The commensal VLA Low-band Ionsophere and Transient Experiment (VLITE) simultaneously detected the source at 339 MHz with a flux density 122.6 +/- 20.4 mJy, indicating a spectral break below 1 GHz. The rotation measure in April 2020 was 63.9 +/- 0.3rad/m2, which almost triples the range of the variable rotation measure observed by Wang et al. (2021) to ~130 rad/m2. The polarization angle, corrected for Faraday rotation, was 97 +/- 6 degrees. The 1.23 GHz linear polarization was 76.7% +/- 3.9% with wavelength-dependent depolarization indicating Faraday depth dispersion sigma_phi = 4.8^{+0.5}_{-0.7} rad/m2. We find an upper limit to circular polarization |V|/I < 10.1%. Interpretation of the data in terms of diffractive scattering of radio waves by a plasma near the source indicates electron density and line-of-sight magnetic field strength within a factor 3 of n_e ~2 cm^{-3} and B_par ~2 x 10^5 microgauss. Combined with causality limits to the size of the source, these parameters are consistent with the low-frequency spectral break resulting from synchrotron self-absorption, not free-free absorption. A possible interpretation of the source is a highly supersonic neutron star interacting with a changing environment.
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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".