The Phoenix Deep Survey: the radio properties of the hard X-ray selected sample
Bibliographic record
Abstract
The radio properties of hard (2-8keV) X-ray selected sources are explored by combining a single 50ks XMM-Newton pointing with the ultra-deep and homogeneous Phoenix radio (1.4GHz) survey (Hopkins et al. 2003). A total of 43 sources are detected above the X-ray flux limit f_X(2-8keV)=7.7e-15cgs with 14 of them exhibiting radio emission above ~40muJy (3sigma). The X-ray/radio matched population lies in the borderline between radio loud and quiet AGNs and comprises sources with both soft and hard X-ray spectral properties suggesting both obscured and unobscured systems. The spectroscopically identified sub-sample (total of 6 X-ray/radio matches) comprises narrow emission line AGNs (4) with hard X-ray spectral properties and broad line sources (2) with soft X-ray spectra. We find evidence that the fraction of X-ray/radio matches increases from ~20% for sources with rest-frame column density N_H<1e22cm^-2 to \~50% for more absorbed systems. Poor statistics however, limit the significance of the above result to the ~2sigma level. Also, the X-ray/radio matched sources have flatter coadded X-ray spectrum (Gamma=1.78^{+0.05}_{-0.03}) compared to sources without radio emission (Gamma=2.00^{+0.03}_{-0.04}). A possible explanation for the higher fraction of absorbed sources with radio emission at the muJy level is the presence of circum-nuclear starburst activity that both feeds and obscures the central engine. For a small sub-sample of z~0.4 radio emitting AGNs with N_H>1e22cm^-2 their combined spectrum exhibits a soft X-ray component that may be associated with star-formation activity, although other possibilities cannot be excluded. We also find that radio emitting AGNs make up about 13-20% of the hard-band X-ray background depending on the adopted normalisation.
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 | 0.001 |
| 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 | 0.000 | 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".