A connection between extremely strong damped Lyman-<i>α</i>systems and Lyman-<i>α</i>emitting galaxies at small impact parameters
Notice bibliographique
Résumé
We present a study of 100 high redshift (z 2-4) extremely strong damped Lyman- systems (ESDLA, with N(H i) 0.5 10 22 cm -2 ) detected in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III) Data Release 11. We study the neutral hydrogen, metal, and dust content of this elusive population of absorbers and confirm our previous finding that the high column density end of the N(H i) frequency distribution has a relatively shallow slope with power-law index -3.6, similar to what is seen from 21-cm maps in nearby galaxies. The stacked absorption spectrum indicates a typical metallicity 1/20th solar, similar to the mean metallicity of the overall DLA population. The relatively small velocity extent of the low-ionisation lines suggests that ESDLAs do not arise from large-scale flows of neutral gas. The high column densities involved are in turn more similar to what is seen in DLAs associated with gamma-ray burst afterglows (GRB-DLAs), which are known to occur close to star-forming regions. This indicates that ESDLAs arise from a line of sight passing at very small impact parameters from the host galaxy, as observed in nearby galaxies. This is also supported by simple theoretical considerations and recent high-z hydrodynamical simulations. We strongly substantiate this picture by the first statistical detection of Ly emission with L ESDLA (Ly ) (0.6 0.2) 10 42 erg s -1 in the core of ESDLAs (corresponding to about 0.1 L at z 2-3), obtained through stacking the fibre spectra (of radius 1 corresponding to 8 kpc at z 2.5). Statistical errors on the Ly luminosity are of the order of 0.1 10 42 erg s -1 but we caution that the measured Ly luminosity may be overestimated by 35% due to sky light residuals and/or FUV emission from the quasar host and that we have neglected flux-calibration uncertainties. We estimate a more conservative uncertainty of 0.2 10 42 erg s -1 . The properties of the Ly line (luminosity distribution, velocity width and velocity offset compared to systemic redshift) are very similar to that of the population of Lyman- emitting galaxies (LAEs) with L LAE (Ly ) 10 41 erg s -1 detected in long-slit spectroscopy or narrow-band imaging surveys. By matching the incidence of ESDLAs with that of the LAEs population, we estimate the high column density gas radius to be about r gas = 2.5 kpc, i.e., significantly smaller than the radius corresponding to the BOSS fibre aperture, making fibre losses likely negligible. Finally, the average measured Ly luminosity indicates a star-formation rate consistent with the Schmidt-Kennicutt law, SFR (M yr -1 ) 0.6/ f esc , where f esc < 1 is the Ly escape fraction. Assuming the typical escape fraction of LAEs, f esc 0.3, the Schmidt-Kennicutt law implies a galaxy radius of about r gal 2.5 kpc. Finally, we note that possible overestimation of the Ly emission would result in both smaller r gas and r gal . Our results support a close association between LAEs and strong DLA host galaxies.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».