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SDSS-V black hole mapper: the index diagram as a tool to disentangle the influence of the host galaxy in quasar spectra

We revisit the Quasar Main Sequence (QMS) by investigating the impact of the stellar component from the host galaxy (HG) on the emission line spectra of the active galactic nuclei (AGNs). We first detect spectra with broad emission lines using a line ratio method for a sample of $\simCastalia Negret...

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Main Authors: Negrete, Castalia Alenka (Author) , Sandoval-Orozco, R (Author) , Ibarra-Medel, H (Author) , Tapia-Benavides, B I (Author) , Assef, R J (Author) , Dultzin, D (Author) , Lacerna, I (Author) , Morrison, S (Author) , Anderson, S F (Author) , Rodríguez Hidalgo, P (Author) , Aydar, C (Author) , Bauer, F E (Author) , Benitez, E (Author) , Bizyaev, D (Author) , Brandt, W N (Author) , Brownstein, J R (Author) , Buchner, J (Author) , Cruz-González, I (Author) , González-Buitrago, D (Author) , Hernández-Toledo, H (Author) , Jenaro-Ballesteros, N (Author) , Koekemoer, A (Author) , Krongold, Y (Author) , Martínez-Aldama, M L (Author) , Pan, K (Author) , Ricci, C (Author) , Salvato, M (Author) , Sánchez, S F (Author) , Serrano-Félix, D (Author) , Schneider, D P (Author) , Sniegowska, M (Author) , Trakhtenbrot, B (Author) , Wu, Q (Author) , Wylezalek, Dominika (Author) , Yang, Q (Author) , Zermeño, R J (Author)
Format: Article (Journal)
Language:English
Published: November 2025
In: Monthly notices of the Royal Astronomical Society
Year: 2025, Volume: 543, Issue: 4, Pages: 4272-4285
ISSN:1365-2966
DOI:10.1093/mnras/staf1711
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1093/mnras/staf1711
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Author Notes:C.A. Negrete, R. Sandoval-Orozco, H. Ibarra-Medel, B.I. Tapia-Benavides, R.J. Assef, D. Dultzin, I. Lacerna, S. Morrison, S.F. Anderson, P. Rodríguez Hidalgo, C. Aydar, F.E. Bauer, E. Benitez, D. Bizyaev, W.N. Brandt, J.R. Brownstein, J. Buchner, I. Cruz-González, D. González-Buitrago, H. Hernández-Toledo, N. Jenaro-Ballesteros, A. Koekemoer, Y. Krongold, M.L. Martínez-Aldama, K. Pan, C. Ricci, M. Salvato, S.F. Sánchez, D. Serrano-Félix, D.P. Schneider, M. Sniegowska, B. Trakhtenbrot, Q. Wu, D. Wylezalek, Q. Yang and R.J. Zermeño
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Summary:We revisit the Quasar Main Sequence (QMS) by investigating the impact of the stellar component from the host galaxy (HG) on the emission line spectra of the active galactic nuclei (AGNs). We first detect spectra with broad emission lines using a line ratio method for a sample of $\simCastalia Negrete high SNR ($>$20) black hole mapper objects (part of the fifth phase of the Sloan Digital Sky Survey). We then built the Index diagram, a novel diagnostic tool using the z-corrected spectra, model-free, designed to easily identify spectra with significant stellar HG contributions and to classify the AGN spectra into three categories based on AGN-HG dominance: HG-dominated (HGD), Intermediate (INT), and AGN-dominated (AGND) sources. A colour-z diagram was used to refine the AGN-HG classification. We subtract the stellar contributions from the HGD and INT spectra before modelling the AGN spectrum to extract the QMS parameters. Our QMS reveals that HGD galaxies predominantly occupy the Population B region with no R$_{\rm {Fe\,{\small II}}}$, with outliers exhibiting R$_{\rm {Fe\,{\small II}}}$  $>$ 1, likely due to HG subtraction residuals and a faint contribution of h$\beta _{\rm BC}$. INT and AGND spectra show similar distributions in the Population A region, while in Population B, a tail of AGND sources becomes apparent. Cross-matching with radio, infrared, and X-ray catalogues, we find that the strongest radio emitters are associated with HGD and INT groups. Strong X-ray emitters are found in INT and AGND sources, also occupying the AGN region in the Wide-field Infrared Survey Explorer colour diagram.
Item Description:Veröffentlicht: 08. Oktober 2025
Gesehen am 02.01.2026
Physical Description:Online Resource
ISSN:1365-2966
DOI:10.1093/mnras/staf1711

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