1,128 research outputs found
Imaging Extended Emission-Line Regions of Obscured AGN with the Subaru Hyper Suprime-Cam Survey
Narrow-line regions excited by active galactic nuclei (AGN) are important for
studying AGN photoionization and feedback. Their strong [O III] lines can be
detected with broadband images, allowing morphological studies of these systems
with large-area imaging surveys. We develop a new technique to reconstruct the
[O III] images using the Subaru Hyper Suprime-Cam (HSC) Survey aided with
spectra from the Sloan Digital Sky Survey (SDSS). The technique involves a
careful subtraction of the galactic continuum to isolate emission from the [O
III]5007 and [O III]4959 lines. Compared to traditional
targeted observations, this technique is more efficient at covering larger
samples with less dedicated observational resources. We apply this technique to
an SDSS spectroscopically selected sample of 300 obscured AGN at redshifts 0.1
- 0.7, uncovering extended emission-line region candidates with sizes up to
tens of kpc. With the largest sample of uniformly derived narrow-line region
sizes, we revisit the narrow-line region size-luminosity relation. The area and
radii of the [O III] emission-line regions are strongly correlated with the AGN
luminosity inferred from the mid-infrared (15 m rest-frame) with a
power-law slope of (statistical and systemic
errors), consistent with previous spectroscopic findings. We discuss the
implications for the physics of AGN emission-line region and future
applications of this technique, which should be useful for current and
next-generation imaging surveys to study AGN photoionization and feedback with
large statistical samples.Comment: 20 pages, 13 figures, MNRAS submitte
Collective Phase Sensitivity
The collective phase response to a macroscopic external perturbation of a
population of interacting nonlinear elements exhibiting collective oscillations
is formulated for the case of globally-coupled oscillators. The macroscopic
phase sensitivity is derived from the microscopic phase sensitivity of the
constituent oscillators by a two-step phase reduction. We apply this result to
quantify the stability of the macroscopic common-noise induced synchronization
of two uncoupled populations of oscillators undergoing coherent collective
oscillations.Comment: 6 pages, 3 figure
Collective dynamical response of coupled oscillators with any network structure
We formulate a reduction theory that describes the response of an oscillator
network as a whole to external forcing applied nonuniformly to its constituent
oscillators. The phase description of multiple oscillator networks coupled
weakly is also developed. General formulae for the collective phase sensitivity
and the effective phase coupling between the oscillator networks are found. Our
theory is applicable to a wide variety of oscillator networks undergoing
frequency synchronization. Any network structure can systematically be treated.
A few examples are given to illustrate our theory.Comment: 4 pages, 2 figure
Onset of Collective Oscillation in Chemical Turbulence under Global Feedback
Preceding the complete suppression of chemical turbulence by means of global
feedback, a different universal type of transition, which is characterized by
the emergence of small-amplitude collective oscillation with strong turbulent
background, is shown to occur at much weaker feedback intensity. We illustrate
this fact numerically in combination with a phenomenological argument based on
the complex Ginzburg-Landau equation with global feedback.Comment: 6 pages, 8 figures; to appear in Phys. Rev.
Effective long-time phase dynamics of limit-cycle oscillators driven by weak colored noise
An effective white-noise Langevin equation is derived that describes
long-time phase dynamics of a limit-cycle oscillator subjected to weak
stationary colored noise. Effective drift and diffusion coefficients are given
in terms of the phase sensitivity of the oscillator and the correlation
function of the noise, and are explicitly calculated for oscillators with
sinusoidal phase sensitivity functions driven by two typical colored Gaussian
processes. The results are verified by numerical simulations using several
types of stochastic or chaotic noise. The drift and diffusion coefficients of
oscillators driven by chaotic noise exhibit anomalous dependence on the
oscillator frequency, reflecting the peculiar power spectrum of the chaotic
noise.Comment: 16 pages, 6 figure
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