5,999 research outputs found
The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models
We present 3D models of biconical outflows combined with a thin dust plane
for investigating the physical properties of the ionized gas outflows and their
effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs).
Using a set of input parameters, we construct a number of models in 3D and
calculate the spatially integrated velocity and velocity dispersion for each
model. We find that three primary parameters, i.e., intrinsic velocity, bicone
inclination, and the amount of dust extinction, mainly determine the simulated
velocity and velocity dispersion. Velocity dispersion increases as the
intrinsic velocity or the bicone inclination increases, while velocity (i.e.,
velocity shifts with respect to systemic velocity) increases as the amount of
dust extinction increases. Simulated emission-line profiles well reproduce the
observed [O III] line profiles, e.g., a narrow core and a broad wing
components. By comparing model grids and Monte Carlo simulations with the
observed [O III] velocity-velocity dispersion (VVD) distribution of ~39,000
type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from
~500 km/s to ~1000 km/s for the majority of AGNs, and up to ~1500-2000 km/s for
extreme cases. The Monte Carlo simulations show that the number ratio of AGNs
with negative [O III] velocity to AGNs with positive [O III] velocity
correlates with the outflow opening angle, suggesting that outflows with higher
intrinsic velocity tend to have wider opening angles. These results demonstrate
the potential of our 3D models for studying the physical properties of gas
outflows, applicable to various observations, including spatially integrated
and resolved gas kinematics.Comment: 14 pages, 14 figures, 2 tables; matched with the ApJ published
versio
Outage-based ergodic link adaptation for fading channels with delayed CSIT
Link adaptation in which the transmission data rate is dynamically adjusted
according to channel variation is often used to deal with time-varying nature
of wireless channel. When channel state information at the transmitter (CSIT)
is delayed by more than channel coherence time due to feedback delay, however,
the effect of link adaptation can possibly be taken away if this delay is not
taken into account. One way to deal with such delay is to predict current
channel quality given available observation, but this would inevitably result
in prediction error. In this paper, an algorithm with different view point is
proposed. By using conditional cdf of current channel given observation, outage
probability can be computed for each value of transmission rate . By
assuming that the transmission block error rate (BLER) is dominated by outage
probability, the expected throughput can also be computed, and can be
determined to maximize it. The proposed scheme is designed to be optimal if
channel has ergodicity, and it is shown to considerably outperform conventional
schemes in certain Rayleigh fading channel model
CMB Spectral -Distortion of Multiple Inflation Scenario
In multiple inflation scenario having two inflations with an intermediate
matter-dominated phase, the power spectrum is estimated to be enhanced on
scales smaller than the horizon size at the beginning of the second inflation,
. We require to make sure that
the enhanced power spectrum is consistent with large scale observation of
cosmic microwave background (CMB). We consider the CMB spectral distortions
generated by the dissipation of acoustic waves to constrain the power spectrum.
The -distortion value can be times larger than the expectation of the
standard CDM model () for , while the
-distortion is hardly affected by the enhancement of the power spectrum.Comment: 16 pages, 5 figure
Spectral Decomposition of Missing Transverse Energy at Hadron Colliders
We propose a spectral decomposition to systematically extract information of
dark matter at hadron colliders. The differential cross section of events with
missing transverse energy (MET) can be expressed by a linear combination of
basis functions. In the case of -channel mediator models for dark matter
particle production, basis functions are identified with the differential cross
sections of sub-processes of virtual mediator and visible particle production
while the coefficients of basis functions correspond to dark matter invariant
mass distribution in the manner of the K\"all\'en-Lehmann spectral
decomposition. For a given MET data set and mediator model, we show that one
can differentiate a certain dark matter-mediator interaction from another
through spectral decomposition.Comment: 6+4 pages, 6 figures, PRL versio
Abrikosov vortex motion and elementary pinning force in a SNS Josephson junction
Procedures have been developed to determine the location of a single Abrikosov vortex in a Superconductor - Normal metal - Superconductor (SNS) Josephson junction and study its motion under the influence of a Lorentz force. A vortex in a SNS junction generates characteristic magnetic field inside the junction and this field, in turn, induces a specified phase across the junction. This phase caused by the vortex changes the critical current characteristics of the junction, that then can be used to locate the vortex inside the junction. A single vortex was successfully trapped in the junction by the field cooling process and the location was determined by the diffraction pattern. Motion of the vortex was induced by the transport current, I[subscript] p, and the vortex was found to move in discrete jumps. By tracing the vortex after successive depinning events, many pinning centers could be identified. From the minimum depinning current, the elementary pinning force associated with an individual pinning site of the Pb - Bi(4 atomic percent) superconducting layer has been measured and found to be of order of 10[superscript]-8 dyne (or 10[superscript]-4 dyne/cm) at T/T[subscript] c = 0.95. The force is asymmetric and different from one pinning site to another. For the given SNS junction, the pinning force of a pinning center is dominant over all other forces associated with the vortex in the junction. In addition, from the experiment the temperature dependence of the pinning force is found to be f[subscript]p ~ (1 - T/T[subscript] c)[superscript]3/2 near T[subscript] c. There are two ingredients for the vortex depinning experiment. First, the N layer of the junction must be thick to reduce the field energy and dipole coupling force of the vortex. Secondly, vortex can be depinned at higher temperatures, at which depinning current is smaller than vortex nucleation current. ftn * DOE Report IS-T 1218. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy
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