The Population of Type~1 Active Galactic Nuclei in Dark Energy Spectroscopic Instrument. I. Profile-dependent Measurements of the Low-redshift Sample
Abstract
We present a spectral analysis of a large sample of low-redshift type 1 active galactic nuclei (AGNs) selected from the first data release of the Dark Energy Spectroscopic Instrument (DESI DR1). For objects at z≤0.9, we perform spectral fitting and ML-assisted refinement, yielding 114,754 type 1 AGNs. We use two fitting schemes that differ only in the broad-line model: the broad Balmer components are fitted with either a Lorentzian function or a sum of Gaussians. The continuum and [O III] luminosity measurements agree closely between the two schemes, whereas the Gaussians scheme generally yields larger broad-Hβ full width at half maximum (FWHM) values, larger virial black hole masses, and lower accretion rates. The adopted broad-Balmer profile also changes the decomposition of narrow Balmer emission. Specifically, the anti-correlation between [O III]λ5007/narrow Hβ and accretion rate is stronger under the Gaussians scheme with a Spearman rank correlation coefficient rs=−0.412, than under the Lorentzian scheme with rs=−0.206; the same tendency is observed in the narrow-line Seyfert 1 galaxies (NLS1s) subset (rs=−0.435 and −0.259 for the Gaussians and Lorentzian schemes, respectively), suggesting that the Gaussians scheme may provide a more self-consistent separation of the broad and narrow Hβ components. Moreover, the consistent correlations recovered under both profile prescriptions favor a continuous type 1 accretion-state sequence, with NLS1s occupying its high-accretion end rather than constituting a distinct population.
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BibTeX
@misc{yao2026population,
title = {{The Population of Type~1 Active Galactic Nuclei in Dark Energy Spectroscopic Instrument. I. Profile-dependent Measurements of the Low-redshift Sample}},
author = {Zhu-Heng Yao and Wei-Jian Guo and Shuo Zhai and Yu-Chang Li and Cheng Cheng and Jun-Rong Liu and Shuang Jin and Antonios Katsianis and Jing Wang and Da-Wei Xu and Jian-Yan Wei},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.13218},
eprint = {2610.13218},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.13218},
}
RIS
TY - UNPB
TI - The Population of Type~1 Active Galactic Nuclei in Dark Energy Spectroscopic Instrument. I. Profile-dependent Measurements of the Low-redshift Sample
AU - Zhu-Heng Yao
AU - Wei-Jian Guo
AU - Shuo Zhai
AU - Yu-Chang Li
AU - Cheng Cheng
AU - Jun-Rong Liu
AU - Shuang Jin
AU - Antonios Katsianis
AU - Jing Wang
AU - Da-Wei Xu
AU - Jian-Yan Wei
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.13218
UR - https://arxiv.org/abs/2610.13218
AB - We present a spectral analysis of a large sample of low-redshift type 1 active galactic nuclei (AGNs) selected from the first data release of the Dark Energy Spectroscopic Instrument (DESI DR1). For objects at z≤0.9, we perform spectral fitting and ML-assisted refinement, yielding 114,754 type 1 AGNs. We use two fitting schemes that differ only in the broad-line model: the broad Balmer components are fitted with either a Lorentzian function or a sum of Gaussians. The continuum and [O III] luminosity measurements agree closely between the two schemes, whereas the Gaussians scheme generally yields larger broad-Hβ full width at half maximum (FWHM) values, larger virial black hole masses, and lower accretion rates. The adopted broad-Balmer profile also changes the decomposition of narrow Balmer emission. Specifically, the anti-correlation between [O III]λ5007/narrow Hβ and accretion rate is stronger under the Gaussians scheme with a Spearman rank correlation coefficient r_s=−0.412, than under the Lorentzian scheme with r_s=−0.206; the same tendency is observed in the narrow-line Seyfert 1 galaxies (NLS1s) subset (r_s=−0.435 and −0.259 for the Gaussians and Lorentzian schemes, respectively), suggesting that the Gaussians scheme may provide a more self-consistent separation of the broad and narrow Hβ components. Moreover, the consistent correlations recovered under both profile prescriptions favor a continuous type 1 accretion-state sequence, with NLS1s occupying its high-accretion end rather than constituting a distinct population.
ER -