Bozkurt, M.
Hudaverdi, M.
Recent observations and numerical simulations show that galaxies are not distributed in the Universe randomly. They are placed like the pearls of a necklace. The matter is spread into the space in the form of cosmic filaments and voids. The intersection regions of these cosmic filaments are what we observe as "clusters of galaxies". In this work we selected 9 clusters of galaxies (A1644, A1736, A3528, A3530, A3532, A3556, A3558, A3560, A3562) from SHAPLEY super cluster region, the largest concentration of galaxies in our nearby Universe. The XMM-Newton and Chandra archival data are used for the analysis. We interpret the morphology of the clusters in the region and gravitational perturbations as a result of close encountering in the Shapley. The cosmic filaments and webs are portrayed from the Shapley super cluster region analysis results.


On the energy-momentum in closed universes
Salti, M (Springer Science and Business Media LLC, 2006-02-01)
Using the Moller, Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum definitions both in general relativity and teleparallel gravity, we find the energy-momentum of the closed universe based on the generalized Bianchi-I type metric.
Spectra, vacua, and the unitarity of Lovelock gravity in D-dimensional AdS spacetimes
Sisman, Tahsin Cagri; Gullu, Ibrahim; Tekin, Bayram (2012-08-24)
We explicitly confirm the expectation that generic Lovelock gravity in D dimensions has a unitary massless spin-2 excitation around any one of its constant curvature vacua just like the cosmological Einstein gravity. The propagator of the theory reduces to that of Einstein's gravity, but scattering amplitudes must be computed with an effective Newton's constant which we provide. Tree-level unitarity imposes a single constraint on the parameters of the theory yielding a wide range of unitary region. As an ex...
Gravitational Waves and 2.5 PN Gravitational Wave Memory
Uçanok, Onur; Tekin, Bayram; Department of Physics (2020-9)
Since the discovery of general relativity, the Einstein field equations have explainedmany phenomenon (e.g. precession of orbits) and predicted others (e.g. gravitational lensing, gravitational time dilation and black holes). Among its many predictions,the wave-like nature of the linearized theory has garnered a lot of attention due to the possiblity of gravitational wave propagation; their effects, their observability andthe complicated nature of gravitational radiation. Many scientists (that can be foun...
Event horizon detecting invariants
Tavlayan, Aydın; Tekin, Bayram (American Physical Society (APS), 2020-04-14)
Some judiciously chosen local curvature scalars can be used to invariantly characterize event horizons of black holes inD > 3 dimensions, but they fail for the three dimensional Banados-Teitelboim-Zanelli (BTZ) black hole since all curvature invariants are constant. Here we provide an invariant characterization of the event horizon of the BTZ black hole using the curvature invariants of codimension one hypersurfaces instead of the full spacetime. Our method is also applicable to black holes in generic dimen...
ZAKOUT, I; Sever, Ramazan (1994-10-01)
We study the relativistic description of heavy qqBAR bound states in the context of the relativistic wave equation. We used some attractive QCD based potentials where the vector part incorporates in the two loop perturbation QCD effects at short distances while the scalar part approaches the linear confining potential at large distances. We calculate the energy levels, leptonic and hadronic decay widths, as well as the E1 rate transition for ccBAR and bbBAR. Results are compared with their experimental v...
Citation Formats
M. Bozkurt, M. Hudaverdi, and E. N. ERCAN, “PROBING THE COSMIC FILAMENTS BY MEANS OF X-RAY OBSERVATIONS,” 2008, vol. 86, p. 347, Accessed: 00, 2020. [Online]. Available: