Journal article
Balmer Absorption in Iron Low-ionization Broad Absorption Line Quasars
The Astrophysical journal, v 993(1), 129
01 Nov 2025
Featured in Collection : Drexel's Newest Publications
Abstract
While C iv is the most common absorption line in broad absorption line quasar spectra, Balmer absorption lines (BALs) are among the rarest. We present analysis of Balmer absorption in a sample of 14 iron low-ionization BAL quasars (FeLoBALQs); eight are new identifications. We measured velocity offset, width, and apparent optical depth. The partial covering that is ubiquitous in BAL quasar spectra alters the measured Balmer optical depth ratios; accounting for this, we estimated the true H(n = 2) column density. We found the anticipated correlation between Eddington ratio and outflow speed, but it is weak in this sample because nearly all of the objects have the low outflow speeds characterizing loitering outflow FeLoBAL quasars, objects that are also found to have low accretion rates. Measurements of dN/dv, the differential column density with respect to the outflow speed, are anticorrelated with the luminosity and Eddington ratio: the strongest absorption is observed at the lowest speeds in the lowest-luminosity objects. The absorption line width is correlated with αoi, the Fλ point-to-point slope between 5100 Å and 3 μm. This parameter is strongly correlated with the Eddington ratio among low-redshift quasars. BALs have been recently found in the spectra of little red dots (LRDs), a class of high-redshift objects discovered by JWST. We note suggestive similarities between LRDs and FeLoBAL quasars in the emission-line shape, the presence of steep reddening and a scattered blue continuum, the lack of hot dust emission, and X-ray weakness.
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Details
- Title
- Balmer Absorption in Iron Low-ionization Broad Absorption Line Quasars
- Creators
- Karen M Leighly - University of OklahomaSarah C Gallagher - Western UniversityHyunseop Choi - Université de MontréalDonald M Terndrup - University of OklahomaJulianna R Voelker - University of OklahomaGordon T Richards - Drexel UniversityLeah K Morabito - Durham University
- Publication Details
- The Astrophysical journal, v 993(1), 129
- Publisher
- IOP Publishing
- Number of pages
- 16
- Grant note
- National Science Foundation (NSF): 2006771
K.M.L. acknowledges useful discussion with Chanuntorn Pumpo, Gilberto Garcia, and Jorge Escalera. Support for SimBAL development and analysis is provided by NSF Astronomy and Astrophysics grants No. 1518382, 2006771, and 2007023. S.C.G. acknowledges the support of the Natural Science and Engineering Research Council (RGPIN-2021-04157) and a Western University Research Leadership Chair Award. L.K.M. is grateful for support from UKRI [MR/Y020405/1].
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:001603854600001
- Other Identifier
- 991022125426204721