Quasars: What Turns Them Off?

2006/06/08 by Robert J. Thacker, Evan Scannapieco, H. M. P. Couchman · 8 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Halo #Luminosity #Luminosity function #OVV quasar #Physics #Quasar #Redshift #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.1086/508650

published as Astrophys.J.653:86-100,2006 · 16 pages, 11 figures, submitted to ApJ, comments welcomed

arxiv created 2006/06/08 · openalex publication_date 2006/12/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

While the high-redshift quasar luminosity function closely parallels the hierarchical growth of dark matter halos, at lower redshifts quasars exhibit an antihierarchical turnoff, which moves from the most luminous objects to the faintest. We explore the idea that this may arise from self-regulating feedback, caused by quasar outflows. Using a hybrid approach that combines a detailed hydrodynamic simulation with observationally derived relationships, we calculate the luminosity function of quasars down to a redshift of z = 1 in a large, cosmologically representative volume. Outflows are included explicitly by tracking halo mergers and driving shocks into the surrounding intergalactic medium, with an energy output equal to a fixed 5% fraction of the bolometric luminosity. Our results are in excellent agreement with measurements of the spatial distribution of quasars on both small and large scales, and we detect an intriguing excess of galaxy-quasar pairs at very short separations. Our results also reproduce an antihierarchical turnoff in the quasar luminosity function; however, this falls short of that observed, as well as that predicted by analogous semianalytic models. The difference can be traced to the treatment of gas heating within galaxies and the presence of in-shock cooling. The simulated galaxy cluster L X - T relationship is close to that observed for z ≈ 1 clusters, but the simulated galaxy groups at z = 1 are significantly perturbed by quasar outflows. Measurements of anomalously high X-ray emission in high-redshift groups, along with detections of 1000 km s -1 winds in poststarburst ellipticals, would provide definitive evidence for the AGN-heating hypothesis.

Citations

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Cited by

• BINARY QUASARS AT HIGH REDSHIFT. I. 24 NEW QUASAR PAIRS ATz∼ 3-4
• A CHARACTERISTIC DIVISION BETWEEN THE FUELING OF QUASARS AND SEYFERTS: FIVE SIMPLE TESTS
• SEARCHING FOR FOSSIL EVIDENCE OF AGN FEEDBACK IN WISE-SELECTED STRIPE-82 GALAXIES BY MEASURING THE THERMAL SUNYAEV–ZEL’DOVICH EFFECT WITH THE ATACAMA COSMOLOGY TELESCOPE
• Simulations of the Sunyaev-Zel'dovich effect from quasars
• Accretion disc particle accretion in major merger simulations
• A simple model to link the properties of quasars to the properties of dark matter haloes out to high redshift
• Using Real and Simulated Measurements of the Thermal Sunyaev–Zel’dovich Effect to Constrain Models of AGN Feedback
• Cool Gas in High-Redshift Galaxies