34 research outputs found
The Sunyaev-Zeldovich Effect as a Probe of Black Hole Feedback
Feedback from supermassive black holes has a substantial but only partially understood impact on structure formation in the universe. The Sunyaev-Zeldovich signal from the hot gas that is present in black hole environments serves, as a potential probe of this feedback mechanism. Using a simple one-dimensional Sedov-Taylor model of energy outflow we calculate the angular power spectrum of the Sunyaev-Zeldovich distortion. The amplitude of temperature fluctuation is of the order of a micro-Kelvin in the cosmic microwave background at arcminute scales. This signal is at or below the noise level of current microwave experiments including the Atacama Cosmology Telescope and the South Pole Telescope. To further investigate this effect we have constructed microwave maps of the resulting distortion around individual black holes from a cosmological hydrodynamic simulation. The simulation employs a self-consistent treatment of star formation, supernova feedback and accretion and feedback from supermassive black holes. We show that the temperature distortion scales approximately with the black hole mass and accretion rate, with a typical amplitude up to a few micro-Kelvin on angular scales around 10 arcseconds. We also discuss the possible techniques for detection of this signal which includes pointed observations from high resolution millimeter wave telescopes and cross-correlation of optical quasar catalogs with microwave maps. We perform a cross-correlation analysis of the signal, by stacking microwave maps of quasars identified in the Sloan Digital Sky Survey. We use the microwave data from the Wilkinson Microwave Anisotropy Probe experiment to do this analysis. We perform a two-component (SZ+Dust) fit to the cross-correlation spectrum. Our results yield a best fit parameter of . This signal is likely to be originating from the Sunyaev-Zeldovich distortions from intervening large scale structures. We show that the Atacama Cosmology Telescope will be able to constrain this signal with a much higher statistical significance. In this work we have shown that a traditional tool of cosmology, namely the microwave background, can be used as a potential probe of feedback from supermassive black holes, which is an interesting problem in theories of galaxy evolution
A Direct Measurement of the Mean Occupation Function of Quasars: Breaking Degeneracies between Halo Occupation Distribution Models
Recent work on quasar clustering suggests a degeneracy in the halo occupation
distribution constrained from two-point correlation functions. To break this
degeneracy, we make the first empirical measurement of the mean occupation
function (MOF) of quasars at by matching quasar positions with
groups and clusters identified in the MaxBCG sample. We fit two models to the
MOF, a power law and a 4-parameter model. The number distribution of quasars in
host halos is close to Poisson, and the slopes of the MOF obtained from our
best-fit models (for the power law case) favor a MOF that monotonically
increases with halo mass. The best-fit slopes are and for the power law model and the 4-parameter model, respectively. We
measure the radial distribution of quasars within dark matter halos and find it
to be adequately described by a power law with a slope . We
measure the conditional luminosity function (CLF) of quasars and show that
there is no evidence that quasar luminosity depends on host halo mass, similar
to the inferences drawn from clustering measurements. We also measure the
conditional black hole mass function (CMF) of our quasars. Although the results
are consistent with no dependence on halo mass, we observe a slight indication
of downsizing of the black hole mass function. The lack of halo mass dependence
in the CLF and CMF shows that quasars residing in galaxy clusters have
characteristic luminosity and black hole mass scales.Comment: Matches the ApJ accepted version (11 pages, 8 figures
Mean Occupation Function of High Redshift Quasars from the Planck Cluster Catalog
We characterise the distribution of quasars within dark matter halos using a
direct measurement technique for the first time at redshifts as high as . Using the Planck Sunyaev-Zeldovich (SZ) catalogue for galaxy groups and the
Sloan Digital Sky Survey (SDSS) DR12 quasar dataset, we assign host
clusters/groups to the quasars and make a measurement of the mean number of
quasars within dark matter halos as a function of halo mass. We find that a
simple power-law fit of \log\left = (2.11 \pm 0.01) \log (M) -(32.77
\pm 0.11) can be used to model the quasar fraction in dark matter halos. This
suggests that the quasar fraction increases monotonically as a function of halo
mass even to redshifts as high as .Comment: Accepted for publication in PAS
The Halo Occupation Distribution of X-ray-Bright Active Galactic Nuclei: A Comparison with Luminous Quasars
We perform halo occupation distribution (HOD) modeling of the projected
two-point correlation function (2PCF) of high-redshift (z~1.2) X-ray-bright
active galactic nuclei (AGN) in the XMM-COSMOS field measured by Allevato et
al. The HOD parameterization is based on low-luminosity AGN in cosmological
simulations. At the median redshift of z~1.2, we derive a median mass of
(1.02+0.21/-0.23)x10^{13} Msun/h for halos hosting central AGN and an upper
limit of ~10% on the AGN satellite fraction. Our modeling results indicate (at
the 2.5-sigma level) that X-ray AGN reside in more massive halos compared to
more bolometrically luminous, optically-selected quasars at similar redshift.
The modeling also yields constraints on the duty cycle of the X-ray AGN, and we
find that at z~1.2 the average duration of the X-ray AGN phase is two orders of
magnitude longer than that of the quasar phase. Our inferred mean occupation
function of X-ray AGN is similar to recent empirical measurements with a group
catalog and suggests that AGN halo occupancy increases with increasing halo
mass. We project the XMM-COSMOS 2PCF measurements to forecast the required
survey parameters needed in future AGN clustering studies to enable higher
precision HOD constraints and determinations of key physical parameters like
the satellite fraction and duty cycle. We find that N^{2}/A~5x10^{6} deg^{-2}
(with N the number of AGN in a survey area of A deg^{2}) is sufficient to
constrain the HOD parameters at the 10% level, which is easily achievable by
upcoming and proposed X-ray surveys.Comment: 11 pages, 4 figures, accepted in Ap