Based on large optical and mid-infrared (IR) surveys, we investigate the relation between nuclear activity in local Seyfert 2 galaxies and galaxy interactions using a statistical neighbour counting technique. At the same level of host galaxy star for
mation (SF), we find that active galactic nuclei (AGNs) with stronger [OIII] emission lines do not show an excess of near neighbours, while AGNs with stronger mid-IR emission do have more near neighbours within a projected distance of 100 kpc. The excess neighbour count increases with decreasing projected radius. These results suggest a phase of torus formation during galaxy interactions.
We analyze a sample of 30,000 nearby obscured AGNs with optical spectra from SDSS and mid-IR photometry from WISE. Our aim is to investigate the AGN host galaxy properties with mid-IR luminosities as AGN activity indicator, and to compare with previo
us studies based on [OIII] emission lines. First we find that the [3.4] - [4.6] colour has weak dependence on host stellar age, but strong dependence on AGN activity. We then use a pair-matching technique to subtract the host 4.6 micron contribution. By combining Seyferts with a sample of SDSS quasars at z < 0.7, we show that the [OIII] and the intrinsic AGN 4.6 micron luminosities correlate roughly linearly over 4 orders of magnitude, but with substantial scatter. We also compare the partition functions of the total integrated 4.6 micron and [OIII] line luminosities from Seyferts and a sub-population of LINERs with significant nuclear 4.6 micron emission, as function of a variety of host galaxy properties, finding that they are identical. We conclude, therefore, that [OIII] as an AGN indicator shows no particular biases as compared to the 4.6 micron luminosity. Our results also demonstrate that some LINERs do fit in with the expectations of the simple Unified Model.
We study the normal form of multipartite density matrices. It is shown that the correlation matrix (CM) separability criterion can be improved from the normal form we obtained under filtering transformations. Based on CM criterion the entanglement wi
tness is further constructed in terms of local orthogonal observables for both bipartite and multipartite systems.
We study the fully entangled fraction of quantum states. An upper bound is obtained for arbitrary dimensional bipartite systems. This bound is shown to be exact for the case of two-qubit systems. An inequality related the fully entangled fraction of
two qubits in a three-qubit mixed state has been also presented.
We investigate the separability of arbitrary dimensional tripartite sys- tems. By introducing a new operator related to transformations on the subsystems a necessary condition for the separability of tripartite systems is presented.
We investigate the separability of quantum states based on covariance matrices. Separability criteria are presented for multipartite states. The lower bound of concurrence proposed in Phys. Rev. A. 75, 052320 (2007) is improved by optimizing the local orthonormal observables.
