Quiescent Host Galaxies of Extended Quasars Revealed by Spectrophotometric Decomposition
Shengxiu Sun, Linhua Jiang, Zhiwei Pan, Małgorzata Siudek, Mar Mezcua, Gaocheng Yin, Swayamtrupta Panda, Wei-Jian Guo, Steven Ahlen, David Brooks, Todd Claybaugh, Axel de la Macorra, Peter Doel, Enrique Gaztañaga, Gaston Gutierrez, Theodore Kisner, Andrew Lambert, Martin Landriau, Aaron Meisner, Ramon Miquel, John Moustakas, Ignasi Pérez-Ráfols, Eusebio Sanchez, David Schlegel, Michael Schubnell, Hee-Jong Seo, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver, Rongpu Zhou
astro-ph.GA, astro-ph.IM
Submitted: 2026-07-30
Comments: Published in The Astrophysical Journal, 1004, 13 (2026), 20 pages, 20 figures
Journal ref: The Astrophysical Journal, 1004, 13 (2026)
License: http://creativecommons.org/licenses/by/4.0/
The gist: Previous works of low-redshift quasar host galaxies have focused on compact quasars and found that their host galaxies are mainly star-forming galaxies.
Terminology
Abstract
Previous works of low-redshift quasar host galaxies have focused on compact quasars and found that their host galaxies are mainly star-forming galaxies. Here we present a study of host galaxies for quasars with extended morphologies in ground-based optical images. We select a sample of more than 1000 type 1 quasars at redshift 0.1<z<1 that are classified as extended objects by DESI. Combining high-resolution spectra from DESI and high-quality images from Subaru HSC, we develop a spectrophotometric decomposition technique to iteratively decompose each quasar into an AGN component and its host galaxy. The technique can effectively break the degeneracy between the AGN and host components and capture the host spectral features. Our results show that the host galaxies of most quasars have low star-formation rates (SFRs) and low specific SFRs, indicating that they are quiescent galaxies. Many of them exhibit prominent post-starburst features with the existence of significant old stellar populations. These properties are quite different from the nature of compact quasars with star-forming host galaxies. In addition, the relation between the black hole mass and stellar mass for our sample is broadly consistent with the canonical local relations. This work is complementary to the previous studies and suggests that the host galaxies of low-redshift quasars are more diverse than what was thought.
Sources
- An Overview of the LSST Image Processing Pipelines
- The DESI Experiment Part I: Science,Targeting, and Survey Design
- The DESI Experiment Part II: Instrument Design
- DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
- DESI 2024 VII: Cosmological Constraints from the Full-Shape Modeling of Clustering Measurements
- Data Release 1 of the Dark Energy Spectroscopic Instrument
- QuasarNET: Human-level spectral classification and redshifting with Deep Neural Networks
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