We have undertaken a spectroscopic survey of gravitational arcs in a carefully chosen sample of six clusters each containing a dominant brightest cluster galaxy. We use these systems to study the relative distributions of dark and baryonic material in the central regions. Three clusters present both radial and tangential arcs and provide particularly strong constraints on the mass profiles, whe...

Strong lensing in galaxy clusters probes properties of dense cores dark matter halos mass, studies the distant universe at flux levels and spatial resolutions otherwise unavailable, constrains cosmological models independently. The next-generation large scale sky imaging surveys are expected to discover thousands cluster-scale strong lenses, which would lead unprecedented opportunities for appl...

A graph is called symmetric if its full automorphism group acts transitively on the set of arcs. The Cayley graph $Gamma=Cay(G,S)$ on group $G$ is said to be normal symmetric if $N_A(R(G))=R(G)rtimes Aut(G,S)$ acts transitively on the set of arcs of $Gamma$. In this paper, we classify all connected tetravalent normal symmetric Cayley graphs of order $p^2q$ where $p>q$ are prime numbers.

Giant arcs in strong lensing galaxy clusters can provide a purely geometric determination of cosmological parameters, such as the dark energy density and equation of state. We investigate sources of noise in cosmography with giant arcs, focusing in particular on errors induced by density fluctuations along the line-of-sight, and errors caused by modeling uncertainties. We estimate parameter err...

We present the results of observations of the extended emission-line region of the Seyfert 2 galaxy Mrk 573, obtained using the WFPC2 camera on board HST and the TIGER integral eld spectrograph on the Canada France Hawaii Telescope. The WFPC2 observations consist of a set of narrow-band linear ramp lter images in the O iii]5007 and H + N ii]6583 lines, as well as continuum and other emission-li...

Abstract High-sensitivity interstellar scintillation and polarization observations of PSR B0656+14 made at three epochs over a year using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) show that scattering is dominated by two different compact regions. We identify one nearer to pulsar with shell Monogem Ring, thereby confirming association. The other probably associated Local ...

the arc costs are assumed to be online parameters of the network and decisions should be made while the costs of arcs are not known. the policies determine the permitted nodes and arcs to traverse and they are generally defined according to the departure nodes of the current policy nodes. in on-line created tours arc costs are not available for decision makers. the on-line traversed nodes are f...

A k-hypertournament H on n vertices, where 2 ≤ k ≤ n, is a pair H = (V,AH), where V is the vertex set of H and AH is a set of k-tuples of vertices, called arcs, such that for all subsets S ⊆ V of order k, AH contains exactly one permutation of S as an arc. Inspired by the successful extension of classical results for tournaments (i.e. 2-hypertournaments) to hypertournaments, by Gutin and Yeo [J...

We consider the problem (MSSS) of finding the minimum number of arcs in a spanning strongly connected subgraph of a strongly connected digraph. This problem is NP-hard for general digraphs since it generalizes the hamiltonian cycle problem. We characterize the number of arcs in a minimum spanning strong subgraph for digraphs which are either extended semicomplete or semicomplete bipartite. Our ...