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

ABSTRACT 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 $\sim$3000 high SNR ($>$20) black hole mapper objects (part of the fifth phase of the Sloan Digital Sky Survey). We then built the Index diagram, a novel diagnostic tool using the z-corrected spectra, model-free, designed to easily identify spectra with significant stellar HG contributions and to classify the AGN spectra into three categories based on AGN–HG dominance: HG-dominated (HGD), Intermediate (INT), and AGN-dominated (AGND) sources. A colour-z diagram was used to refine the AGN–HG classification. We subtract the stellar contributions from the HGD and INT spectra before modelling the AGN spectrum to extract the QMS parameters. Our QMS reveals that HGD galaxies predominantly occupy the Population B region with no R$_{\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.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-10-07
DOI
https://doi.org/10.1093/mnras/staf1711
Primary Topic
Astronomy and Astrophysical Research
Type
article
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0.00

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article

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

C. A. Negrete, Sean Morrison, Scott F. Anderson, W. N. Brandt et al.
Monthly Notices of the Royal Astronomical Society
Astronomy and Astrophysical Research
article

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

C. A. Negrete, Sean Morrison, Scott F. Anderson, W. N. Brandt, D. Dultzin, Héctor J. Ibarra-Medel, Cláudio Ricci, Y. Krongold, F. E. Bauer, Mary Loli Martínez‐Aldama, Roberto J. Assef, Qian Wu, D. González–Buitrago, Kaike Pan, Qian Yang, E. Benítez, M. Salvato, Anton M. Koekemoer, Benny Trakhtenbrot, Dmitry Bizyaev, Dominika Wylezalek, Ivan Lacerna, I. Cruz-González, Rodrigo Sandoval-Orozco, Johannes Büchner, H. M. Hernández-Toledo, Joel R. Brownstein, S. F. Sánchez, Donald P. Schneider, Marzena Śniegowska, Nancy Jenaro-Ballesteros, P Rodríguez Hidalgo C Aydar, D Serrano-Félix, R J Zermeño, B I Tapia-Benavides
article en

Abstract

ABSTRACT 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 $\sim$3000 high SNR ($>$20) black hole mapper objects (part of the fifth phase of the Sloan Digital Sky Survey). We then built the Index diagram, a novel diagnostic tool using the z-corrected spectra, model-free, designed to easily identify spectra with significant stellar HG contributions and to classify the AGN spectra into three categories based on AGN–HG dominance: HG-dominated (HGD), Intermediate (INT), and AGN-dominated (AGND) sources. A colour-z diagram was used to refine the AGN–HG classification. We subtract the stellar contributions from the HGD and INT spectra before modelling the AGN spectrum to extract the QMS parameters. Our QMS reveals that HGD galaxies predominantly occupy the Population B region with no R$_{\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.

Monthly Notices of the Royal Astronomical SocietyVol. 543(4)
New Mexico State University (US), Space Telescope Science Institute (US), Pennsylvania State University (US), University of Illinois Urbana-Champaign (US), Tel Aviv University (IL), Universidad Autónoma de la Ciudad de México (MX), University of Concepción (CL), University of Tarapacá (CL), Lomonosov Moscow State University (RU), University of Washington (US), University of Atacama (CL), Peking University (CN), University of Utah (US), Heidelberg University (DE), National Solar Observatory (US), Max Planck Institute for Extraterrestrial Physics (DE), Millennium Institute of Astrophysics (CL), Excellence Cluster Origins (DE), Kavli Institute for Theoretical Sciences (CN), Center for Astrophysics Harvard & Smithsonian (US), Instituto de Astrofísica de Canarias (ES), Astronomical Institute of the Slovak Academy of Sciences (SK), University of Washington Bothell (US), Universidad Nacional de Concepción (PY), Seattle University (US), Universidad Nacional Autónoma de México (MX), Universidad Diego Portales (CL)
National Science Foundation, Smithsonian Institution, Alfred P. Sloan Foundation, Yale University, Carnegie Institution of Washington, Ohio State University, California Institute of Technology, Harvard University, Johns Hopkins University, New Mexico State University, Space Telescope Science Institute, Flatiron Health, École Polytechnique Fédérale de Lausanne, University of Toronto, Universidad Nacional Autónoma de México, Yunnan University, Nanjing University, China National Textile and Apparel Council, Leibniz-Institut für Astrophysik Potsdam, Agencia Nacional de Investigación y Desarrollo, Max-Planck-Institut für Astronomie, University of Illinois at Urbana-Champaign, University of Colorado Boulder, Smithsonian Astrophysical Observatory, Leibniz-Gemeinschaft, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, National Astronomical Observatories, Chinese Academy of Sciences
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