338 research outputs found
Multi-epoch analysis of the X-ray spectrum of the active galactic nucleus in NGC 5506
We present a multi-epoch X-ray spectroscopy analysis of the nearby
narrow-line Seyfert I galaxy NGC 5506. For the first time, spectra taken by
Chandra, XMM-Newton, Suzaku, and NuSTAR - covering the 2000-2014 time span -
are analyzed simultaneously, using state-of-the-art models to describe
reprocessing of the primary continuum by optical thick matter in the AGN
environment. The main goal of our study is determining the spin of the
supermassive black hole (SMBH). The nuclear X-ray spectrum is photoelectrically
absorbed by matter with column density cm. A
soft excess is present at energies lower than the photoelectric cut-off. Both
photo-ionized and collisionally ionized components are required to fit it. This
component is constant over the time-scales probed by our data. The spectrum at
energies higher than 2 keV is variable. We propose that its evolution could be
driven by flux-dependent changes in the geometry of the innermost regions of
the accretion disk. The black hole spin in NGC 5506 is constrained to be
0.93 at 90% confidence level for one interesting
parameter.Comment: 13 pages, 9 figures. v2: refereed versio
Deep Reinforcement Learning for Resource Management in Network Slicing
Network slicing is born as an emerging business to operators, by allowing
them to sell the customized slices to various tenants at different prices. In
order to provide better-performing and cost-efficient services, network slicing
involves challenging technical issues and urgently looks forward to intelligent
innovations to make the resource management consistent with users' activities
per slice. In that regard, deep reinforcement learning (DRL), which focuses on
how to interact with the environment by trying alternative actions and
reinforcing the tendency actions producing more rewarding consequences, is
assumed to be a promising solution. In this paper, after briefly reviewing the
fundamental concepts of DRL, we investigate the application of DRL in solving
some typical resource management for network slicing scenarios, which include
radio resource slicing and priority-based core network slicing, and demonstrate
the advantage of DRL over several competing schemes through extensive
simulations. Finally, we also discuss the possible challenges to apply DRL in
network slicing from a general perspective.Comment: The manuscript has been accepted by IEEE Access in Nov. 201
- …