251 research outputs found

    Magnetic Fields of Nearby Active Galactic Nuclei and Correlation of the Highest-Energy Cosmic Rays with their Positions

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    The correlation between the pointing direction of ultra high energy cosmic rays and AGN observed by the Pierre Auger Collaboration is explained in the framework of acceleration process in AGN. This acceleration process is produced by a rotating accretion disk around a black hole that is frozen-in magnetic field. In a result the accretion disk is acting as a induction accelerator of cosmic rays. We estimate the resulting magnetic field in the framework of the magnetic coupling process. The results of our calculations allow to make the conclusion that the Flat Spectrum Radio Quasars appear the effective cosmic accelerators. We estimate also the attenuation of highest-energy cosmic rays in a result of their interaction with ambient radiation field.Comment: 5 page

    Photon-Axion-Like Particle Coupling Constant and Cosmological Observations

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    We estimated the photon-pseudoscalar particle mixing constant from the effect of cosmological alignment and cosmological rotation of polarization plane of distant QSOs. This effect is explained in terms of birefringent phenomenon due to photon-pseudoscalar (axion-like) particle mixing in a cosmic magnetic field. On the contrary, one can estimate the strength of the cosmic magnetic field using the constraints on the photon-axion-like particle coupling constant from the CAST experiment and from SNe Ia dimming effect. In a result, the lower limit on the intergalactic (z≈1÷2z\approx 1\div 2) magnetic field appears at the level of about 4×10−10÷10−114\times 10^{-10}\div 10^{-11} G.Comment: 8 page

    Synchrotron Self-Absorption Process in GRBs and the Isotropic Energy - Peak Energy Fundamental Relation

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    The existence of strong correlation between the peak luminosity (and/or bolometric energetics) of Gamma Ray Bursts (GRB) is one of the most intrigue problem of GRB physics. This correlation is not yet understood. Here we demonstrate that this correlation can be explained in framework of synchrotron self-absorption (SSA) mechanism of GRB prompt emission. We estimate the magnetic field strength of the central engine at the level B∼1014(103/Γ)3(1+z)2B\sim 10^{14} (10^3/\Gamma)^3 (1+z)^2, where Γ\Gamma is the Lorentz factor of fireball.Comment: 5 page

    Magnetic fields of active galaxy nuclei and cosmological models

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    We present the review of various methods of detection of magnetic field strengths in the nearest regions of the active galaxy nuclei (AGN) which are the high energetic machines. Original spectropolarimetric method developed in the Pulkovo Observatory allows us to determine the magnitude and geometry of the magnetic field in the region of the optical and more hard electromagnetic radiation. The results of theoretical calculations are compared to the results of spectropolarimetric observations of AGN. We used the method of determining magnetic fields through the spectrum synchrotron radiation in the region of synchrotron self-absorption. As the magnitude of magnetic field of the extragalactic source depends very strongly on the angular size of extragalactic source and therefore on the photometric distance the calculated magnetic field magnitudes depends very strongly on the definite cosmological model. This result allows us to present the new method for determination of the most important cosmological parameters including dark matter and dark energy parameters.Comment: 8 pages, 7 figure

    Impact of Baryonic Physics on Intrinsic Alignments

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    We explore the effects of specific assumptions in the subgrid models of star formation and stellar and AGN feedback on intrinsic alignments of galaxies in cosmological simulations of "MassiveBlack-II" family. Using smaller volume simulations, we explored the parameter space of the subgrid star formation and feedback model and found remarkable robustness of the observable statistical measures to the details of subgrid physics. The one observational probe most sensitive to modeling details is the distribution of misalignment angles. We hypothesize that the amount of angular momentum carried away by the galactic wind is the primary physical quantity that controls the orientation of the stellar distribution. Our results are also consistent with a similar study by the EAGLE simulation team.Comment: 7 pages, 6 figures, submitted to Ap

    Probing the universe with the Lyman-α\alpha forest; 3, The mean opacity of the IGM

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    I apply the well controlled Hydro-PM approximation of Gnedin & Hui to study the consistency between the column density distribution of the Lyman-alpha forest and the mean opacity of the IGM for 25 different flat cosmological scenarios, including variants of the standard CDM, tilted CDM, CDM with a cosmological constant, and CHDM models. I show that the observational data of Press, Rybicki, and Schneider are not compatible with the hypothesis that the Lyman-alpha forest arises from fluctuations in the low density IGM, whereas the data of Zuo and Lu and Lu et al. are in a full agreement with the level of the ionizing intensity required to reproduce the observed column density distribution of the Lyman-alpha forest. Thus, either the data of Press, Rybicki, and Schneider are contaminated, or the hypothesis that the Lyman-alpha forest arises from density fluctuations in the IGM is invalid

    Probing the universe with the Lyman-α\alpha forest; 2, The column density distribution

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    I apply the well controlled Hydro-PM approximation of Gnedin & Hui to model the column density distribution of the Lyman-alpha forest for 25 different flat cosmological scenarios, including variants of the standard CDM, tilted CDM, CDM with a cosmological constant, and CHDM models. I show that within the accuracy of the HPM approximation the slope of the column density distribution reflects the degree of nonlinearity of the cosmic gas distribution and is a function of the rms linear density fluctuation at the characteristic filtering scale only. The amplitude of the column density distribution, expressed as the value for the ionizing intensity, is derived as a function of the cosmological parameters (to about 30% accuracy). The observational data are currently consistent with the value for the ionizing intensity both being constant in the redshift interval z~2-4 and peaking by about 30% at z~3. The majority (if not all) of flat cosmological models have difficulty in simultaneously achieving sufficiently low power spectrum amplitude at the cluster scale to fit the observed cluster abundances, and sufficiently high amplitude at the Lyman-alpha forest scale to reproduce the observed shallow column density distribution. While the discrepancy is not statistically significant at the moment, if confirmed in the future, it may indicate that there exist another population of objects contributing to the unsaturated Lyman-alpha absorption along lines of sight towards distant quasars

    Astrophysical Polarimetric Signature Against TeV Fundamental Planck Scale

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    I present the analysis of data of astrophysical polarimetric observations that gives the signature of the fundamental extra dimension Planck scale magnitude essentially higher than  1TeV~1TeV. Magnetic conversion of photons into the fundamental particles (scalars, gravitons) is the probable mechanism that can produce noticeable amount of polarization of optical radiation of astrophysical objects, especially, of distant extragalactic sources. The results of magnetic conversion process of optical light of extragalactic sources are presented for a number of situations including: (a) intergalactic magnetic field, (b) galaxy cluster magnetic field, (c) magnetic conversion in the typical galaxy magnetic field, (d) magnetic conversion of CMB radiation

    Constraints on Spin of a Supermassive Black Hole in Quasars with Big Blue Bump

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    We determined the spin value of supermassive black hole (SMBH) in active galactic nuclei (AGN) with investigated ultraviolet-to-optical spectral energy distribution, presented in the sample of Shang et al. (2005). The estimates of the spin values have been produced at the base of the standard geometrically thin accretion disk model and with using the results of the polarimetric observations. The polarimetric observations are very important for determining the inclination angle of AGN disk. We presented the results of our determinations of the radiation efficiency of the accretion flow and values of the spins of SMBHs, that derives the coefficient of radiation efficiency. The majority of SMBHs of AGNs from Shang et al. (2005) sample are to be the Kerr black holes with the high spin value.Comment: 5 pages, 1 figur

    Magnetic Fields of Black Holes and the Variability Plane

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    We estimated the magnetic field strength at the horizon radius of black holes, that is derived by the magnetic coupling process and depended on the black hole mass MBHM_{BH} and the accretion rate M˙\dot{M}. Our estimation is based on the use of the fundamental variability plane for stellar mass black holes, AGNs and QSOs. The typical values of magnetic field strength on the black hole horizon are appeared at the level of BBH∼108B_{BH}\sim 10^8G for stellar mass black holes and BBH∼104B_{BH}\sim 10^4G for the supermassive black holes. We have obtained the relation pl∼νb−1/2p_l\sim \nu^{-1/2}_b between the intrinsic polarization of the accretion disk radiation and the characteristic frequency of the black hole X-ray variability.Comment: 4 page
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