Fractal properties of SDSS quasars

Rozgacheva, I. K.; Agapov, Aleksei

doi:10.48550/arxiv.1101.4280

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…The fractal analysis has been extensively used in astronomy and astrophysics for the study of the fractal properties of gamma ray bursts (Shakura et al 1994), the critical properties of spherically symmetric accretion in a fractal medium (Roy & Ray 2007), for the analysis of fractal structures in the photospheric and the coronal magnetic field of the Sun (Ioshpa et al 2008;Dimitropoulou et al 2009), as a measure of the scale of homogeneity (Yadav et al 2010), for the study of the star forming regions (Sánchez et al 2010) and for the analysis of the dark matter and gas distributions in the Mare-Nostrum universe (Gaite 2010). The quasar distribution on the celestial sphere is characterized by power laws as well with correlation dimension values ranging from 1.49 to 1.58 for different redshift layers in the same range (Rozgacheva & Agapov 2011a). A fractal cosmological model, which accounts for the observable fractal properties of the large-scale structure of the Universe, was discussed in Rozgacheva & Agapov (2011b).…”

Section: Introductionmentioning

confidence: 99%

Fractal dimension and thermodynamic fluctuation properties of IDV light curves

Leung¹,

Wei²,

Kong³

et al. 2011

Res. Astron. Astrophys.

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Fractals are a basic tool to phenomenologically describe natural objects having a high degree of temporal or spatial variability. From a physical point of view the fractal properties of natural systems can also be interpreted by using the standard formalism of thermodynamical fluctuations. In the present paper we introduce and analyze the fractal dimension of the Intra -Day-Variability (IDV) light-curves of the BL Lac objects, in the optical, radio and X-ray bands, respectively. A general description of the fluctuation spectrum of these systems based on general thermodynamical principles is also proposed. Based on the general fractal properties of a given physical system, we also introduce the predictability index for the IDV light curves. We have explicitly determined the fractal dimension for the R-band observations of five blazars, as well as for the radio band observations of the compact extragalactic radio source J 1128+5925, and of several X-ray sources. Our results show that the fractal dimension of the optical and X-ray observations indicates an almost pure "Brownian noise" (random walk) spectrum, with a very low predictability index, while in the radio band the predictability index is much higher. We have also studied the spectral properties of the IDV light curves, and we have shown that their spectral index is very closely correlated with the corresponding fractal dimension.

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Section: Introductionmentioning

confidence: 99%

Fractal dimension and thermodynamic fluctuation properties of IDV light curves

Leung¹,

Wei²,

Kong³

et al. 2011

Res. Astron. Astrophys.

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“…We call the fractal properties of the large-scale galaxy distribution and the CMB angular anisotropy by the fractal properties of the observable Universe. We have analyzed the fractal properties in our papers [1], [2], [3] (see references there and the excellent review in book [4]). We adduce here some power-laws indicating the fractality.…”

Section: Introductionmentioning

confidence: 99%

The anisotropy properties of a background radiation in the fractal cosmological model

Rozgacheva,

Agapov

2012

Preprint

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We consider the anisotropy properties of a background radiation in the fractal cosmological model. The space of this model includes self-similar domains. The metric tensors of any two domains are connected by the discrete scaling transformation. Photons of the background radiation cross the domain and their energy change. Any observer receives these photons from different domains and detects spots with different brightness. The power spectrum of the brightness anisotropy of the background radiation in the fractal cosmological model is calculated. It is shown this spectrum is closed to the observed angular power spectrum of the SDSS-quasar distribution on the celestial sphere. Only qualitatively it conforms to the angular power spectrum of CMB (WMAP-7).

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“…In the previous paper [8] the analysis of the quasar distribution according to the seventh version of the largest at present survey SDSS has been carried out. This distribution possesses fractal properties as well.…”

Section: Introductionmentioning

confidence: 99%

The fractal cosmological model

Rozgacheva,

Agapov

2011

Preprint

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The fractal cosmological model which accounts for observable fractal properties of the Universe's large-scale structure is constructed. In this framework these properties are consequences of the rotary symmetry of charged scalar meson matter field (complex field). They may be explained through a conception of the Universe as an assembly of self-similar space-time domains. We have found the scale invariant solutions of Einstein's equation and Lagrange's field equation. For the solution the space-time domains with field values related by the scaling are geometrically similar and evolve similarly. Due to this, fractal properties of initial density perturbations which lead to formation of the large-scale structure remain during the gravitational evolution and lead to presence of the fractal properties in the large-scale structure.

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Fractal properties of SDSS quasars

Cited by 3 publications

References 6 publications

Fractal dimension and thermodynamic fluctuation properties of IDV light curves

Fractal dimension and thermodynamic fluctuation properties of IDV light curves

The anisotropy properties of a background radiation in the fractal cosmological model

The fractal cosmological model

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