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Towards modelling ghostly damped Ly α s
- Source :
- Monthly Notices of the Royal Astronomical Society, Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2021, 502 (3), pp.3855-3869. ⟨10.1093/mnras/stab173⟩, Monthly notices of the Royal Astronomical Society, 2021, Vol.502(3), pp.3855-3869 [Peer Reviewed Journal]
- Publication Year :
- 2021
- Publisher :
- HAL CCSD, 2021.
-
Abstract
- We use simple models of the spatial structure of the quasar broad-line region (BLR) to investigate the properties of so-called ghostly damped Ly α (DLA) systems detected in Sloan Digital Sky Survey (SDSS) data. These absorbers are characterized by the presence of strong metal lines but no H i Ly α trough is seen in the quasar spectrum indicating that, although the region emitting the quasar continuum is covered by an absorbing cloud, the BLR is only partially covered. One of the models has a spherical geometry, another one is the combination of two wind flows, whereas the third model is a Keplerian disc. The models can reproduce the typical shape of the quasar Ly α emission and different ghostly configurations. We show that the DLA H i column density can be recovered precisely independently of the BLR model used. The size of the absorbing cloud and its distance to the centre of the AGN are correlated. However, it may be possible to disentangle the two using an independent estimate of the radius from the determination of the particle density. Comparison of the model outputs with SDSS data shows that the wind and disc models are more versatile than the spherical one and can be more easily adapted to the observations. For all the systems, we derive log N(H i)(cm−2) > 20.5. With higher quality data, it may be possible to distinguish between the models.
- Subjects :
- Physics
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
010308 nuclear & particles physics
Spatial structure
Astrophysics::High Energy Astrophysical Phenomena
Astronomy and Astrophysics
Quasar
Astrophysics
Radius
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
Spherical geometry
quasars: emission lines
quasars: absorption lines
Space and Planetary Science
0103 physical sciences
Continuum (set theory)
Particle density
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
Line (formation)
Subjects
Details
- Language :
- English
- ISSN :
- 00358711 and 13652966
- Database :
- OpenAIRE
- Journal :
- Monthly Notices of the Royal Astronomical Society, Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2021, 502 (3), pp.3855-3869. ⟨10.1093/mnras/stab173⟩, Monthly notices of the Royal Astronomical Society, 2021, Vol.502(3), pp.3855-3869 [Peer Reviewed Journal]
- Accession number :
- edsair.doi.dedup.....87c9366a7966d5f24582d0c52782bd5d