118378844
The rms–flux relations in different branches in Cyg X-2
In this paper, the rms-flux (root mean square-flux) relation along the Z-track of the bright Z-Source Cyg X-2 is analyzed using the observational data of Rossi X-ray Timing Explorer (RXTE). Three types of rms-flux relations, i.e. positive, negative, and ‘arch’-like correlations are found in different branches. The rms is positively correlated with flux in normal branch (NB), but anti-correlated in the vertical horizontal branch (VHB). The rms–flux relation shows an ‘arch’-like shape in the horizontal branch (HB). We also try to explain this phenomenon using existing models.
17090886
Rms–flux relation of Cyg X-1 with RXTE: dipping and nondipping cases
Abstract
The rms (root mean square) variability is the parameter for understanding the emission temporal properties of X-ray binaries (XRBs) and active galactic nuclei (AGN). The rms–flux relation with Rossi X-ray Timing Explorer (RXTE) data for the dips and nondip of black hole Cyg X-1 has been investigated in this paper. Our results show that there exist the linear rms–flux relations in the frequency range 0.1–10 Hz for the dipping light curve. Moreover, this linear relation still remains during the nondip regime, but with the steeper slope than that of the dipping case in the low energy band. For the high energy band, the slopes of the dipping and nondipping cases are hardly constant within errors. The explanations of the results have been made by means of the “Propagating Perturbation” model of Lyubarskii (Lyubarskii, Y.E., Mon. Not. Roy. Astron. Soc. 292, 679–685 (1997)).

119217076
Scattering amplitudes in Lifshitz spacetime
AbstractWe consider the calculation of scattering amplitudes in eld theories dual to Lifshitzspacetimes. These amplitudes provide an interesting probe of the IR structure of the eldtheory; our aim is to use them to explore the observable consequences of the singularityin the spacetime. We assume the amplitudes can be related by T-duality to a Wilsonloop, as in the AdS case, and determine the bulk minimal surfaces for the simplest cuspWilson loop. We use this to determine the leading IR singularity in the amplitude. We nd there is a stronger IR singularity for z > 1 than for z = 1, with a coecient whichvanishes as z !1. 1 Introduction The application of holography to non-relativistic theories represents an interesting extension ofthe usual holographic dictionary. The simplest example of this type is the Lifshitz spacetime[1]. The geometry isds 2 = dt 2 r 2z +dr + d~x 2 r(1)where there are d s spatial dimensions ~x, and we have set the curvature scale to one for con-venience. The spacetime has an isometry under t!
55161279
Extending the non-singular hyperscaling violating spacetimes
Lifshitz and hyperscaling violating geometries, which provide a holographic description of non-relativistic eld theories, generically have a singularity in the infrared region of the geometry, where tidal forces for freely falling observers diverge, but there is a special class of hyperscaling violating geometries where this tidal force divergence does not occur. We explicitly construct a smooth extension of the spacetime in this case, and explore the structure of the spacetime. We nd that the spacetime has two disconnected boundaries, as in AdS2. We also consider the behaviour of nite-energy excitations of the spacetime at the horizon, arguing that they will have some divergence there.