Quasars

What turns them off?

Robert J. Tracker, Evan Scannapieco, H. M P Couchman

Research output: Contribution to journalArticle

53 Citations (Scopus)

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 LX-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.

Original languageEnglish (US)
Pages (from-to)86-100
Number of pages15
JournalAstrophysical Journal
Volume653
Issue number1 I
DOIs
StatePublished - Dec 10 2006
Externally publishedYes

Fingerprint

quasars
outflow
luminosity
heating
galaxies
merger
halos
hydrodynamics
shock
spatial distribution
cooling
galactic clusters
automatic control
intergalactic media
simulation
energy
dark matter
output
x rays

Keywords

  • Cosmology: theory
  • Galaxies: evolution
  • Intergalactic medium
  • Large-scale structure of universe
  • Quasars: general

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Tracker, R. J., Scannapieco, E., & Couchman, H. M. P. (2006). Quasars: What turns them off? Astrophysical Journal, 653(1 I), 86-100. https://doi.org/10.1086/508650

Quasars : What turns them off? / Tracker, Robert J.; Scannapieco, Evan; Couchman, H. M P.

In: Astrophysical Journal, Vol. 653, No. 1 I, 10.12.2006, p. 86-100.

Research output: Contribution to journalArticle

Tracker, RJ, Scannapieco, E & Couchman, HMP 2006, 'Quasars: What turns them off?', Astrophysical Journal, vol. 653, no. 1 I, pp. 86-100. https://doi.org/10.1086/508650
Tracker, Robert J. ; Scannapieco, Evan ; Couchman, H. M P. / Quasars : What turns them off?. In: Astrophysical Journal. 2006 ; Vol. 653, No. 1 I. pp. 86-100.
@article{ea4ed20b85bb4df28f543e44b93d00cb,
title = "Quasars: What turns them off?",
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 LX-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.",
keywords = "Cosmology: theory, Galaxies: evolution, Intergalactic medium, Large-scale structure of universe, Quasars: general",
author = "Tracker, {Robert J.} and Evan Scannapieco and Couchman, {H. M P}",
year = "2006",
month = "12",
day = "10",
doi = "10.1086/508650",
language = "English (US)",
volume = "653",
pages = "86--100",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 I",

}

TY - JOUR

T1 - Quasars

T2 - What turns them off?

AU - Tracker, Robert J.

AU - Scannapieco, Evan

AU - Couchman, H. M P

PY - 2006/12/10

Y1 - 2006/12/10

N2 - 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 LX-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.

AB - 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 LX-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.

KW - Cosmology: theory

KW - Galaxies: evolution

KW - Intergalactic medium

KW - Large-scale structure of universe

KW - Quasars: general

UR - http://www.scopus.com/inward/record.url?scp=33845988385&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33845988385&partnerID=8YFLogxK

U2 - 10.1086/508650

DO - 10.1086/508650

M3 - Article

VL - 653

SP - 86

EP - 100

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 I

ER -