Polarimetry of the Ly-alpha envelope of the radio-quiet quasar SDSS J124020.91+145535.6
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arXiv
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| Autori principali: | , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| author | North, P. Hayes, M. Millon, M. Verhamme, A. Trebitsch, M. Blaizot, J. Courbin, F. Chelouche, D. |
| author_facet | North, P. Hayes, M. Millon, M. Verhamme, A. Trebitsch, M. Blaizot, J. Courbin, F. Chelouche, D. |
| contents | The radio-quiet quasar SDSS J1240+1455 lies at a redshift of z=3.11, is surrounded by a Ly-alpha blob (LAB), and is absorbed by a proximate damped Ly-alpha system. In order to better define the morphology of the blob and determine its emission mechanism, we gathered deep narrow-band images isolating the Ly-alpha line of this object in linearly polarized light. We provide a deep intensity image of the blob, showing a filamentary structure extending up to 16'' (or ~122 physical kpc) in diameter. No significant polarization signal could be extracted from the data, but 95% probability upper limits were defined through simulations. They vary between ~3% in the central 0.75'' disk (after subtraction of the unpolarized quasar continuum) and ~10% in the 3.8-5.5'' annulus. The low polarization suggests that the Ly-alpha photons are emitted mostly in situ, by recombination and de-excitation in a gas largely ionized by the quasar ultraviolet light, rather than by a central source and scattered subsequently by neutral hydrogen gas. This blob shows no detectable polarization signal, contrary to LAB1, a brighter and more extended blob that is not related to the nearby active galactic nucleus (AGN) in any obvious way, and where a significant polarization signal of about 18% was detected. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_08488 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Polarimetry of the Ly-alpha envelope of the radio-quiet quasar SDSS J124020.91+145535.6 North, P. Hayes, M. Millon, M. Verhamme, A. Trebitsch, M. Blaizot, J. Courbin, F. Chelouche, D. Astrophysics of Galaxies The radio-quiet quasar SDSS J1240+1455 lies at a redshift of z=3.11, is surrounded by a Ly-alpha blob (LAB), and is absorbed by a proximate damped Ly-alpha system. In order to better define the morphology of the blob and determine its emission mechanism, we gathered deep narrow-band images isolating the Ly-alpha line of this object in linearly polarized light. We provide a deep intensity image of the blob, showing a filamentary structure extending up to 16'' (or ~122 physical kpc) in diameter. No significant polarization signal could be extracted from the data, but 95% probability upper limits were defined through simulations. They vary between ~3% in the central 0.75'' disk (after subtraction of the unpolarized quasar continuum) and ~10% in the 3.8-5.5'' annulus. The low polarization suggests that the Ly-alpha photons are emitted mostly in situ, by recombination and de-excitation in a gas largely ionized by the quasar ultraviolet light, rather than by a central source and scattered subsequently by neutral hydrogen gas. This blob shows no detectable polarization signal, contrary to LAB1, a brighter and more extended blob that is not related to the nearby active galactic nucleus (AGN) in any obvious way, and where a significant polarization signal of about 18% was detected. |
| title | Polarimetry of the Ly-alpha envelope of the radio-quiet quasar SDSS J124020.91+145535.6 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2402.08488 |